# Forrest Edwards radial 5



## josodl1953 (Dec 10, 2016)

Hi there!
Following my thread in the welcome section, I started  to explore the possibilities for the build of the Forrest Edwards radial, in a slightly downsized version. As explained in  the aforementioned thread, I intend to use some bike hub gears for the cam drive. In order to see if this works, I made a mock-up withe some scrap metal to chweck the center distances of the gears.Now there is a problem when downsizing this engine, I intend to downsize to 80% of the original size. The shaft of the idler gear in the original design is supported at one side only, in the crankcase. I want to fit the idler gears on a shaft, supported on both sides withe miniature ball bearings.I put it al together and it works rather nice, no excess backlash and no binding.[/ATTACH]

So, up to the next step.I will make a wooden model to get an idea of the size of the machine and to try some design changes.

To be continued....
_Jos_


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## josodl1953 (Jun 16, 2017)

In the winter I have been working on a wooden model of the downsized (80%) Edwards.I do  not have milling equipment so I try to make as most parts as possible by turning. This is not a big problem because most parts that need a milling operation ( conrods, cylinder head cooling fins,rocker arms) can be made on the toolpost of my lathe (Emco Compact 8-  Austrian made).  I started withe the crankcase,made of two layers of 1 mm plywood wrapped around a piece of steel tubing , glued with polyurethane glue and  clamped withe two big hose clamps.Pieces of 3 mm plywood were glued on the circumference and a 8 mm plywood ring was glued inside. This engine will have a two-part crankcase, partly to reduce the risk  of machining erors, partly because  it is easier to machine and ,most of all, the state of raw material. Having worked 17 years as a QA engineer in the manufactring industry, I collected a vast amount of rejected parts, left over blanks, obsolete bar stock etc. I have excellent material for the crankcase bus it has a hole in the middle...Apart from this, machining the bearing seatings for the idler shaft at the exact center distance can be a tricky operation so it is easier to do this with a separate bearing cover than with an almost completed one-piece crankcase. So, after glueing an turning the inside of the crankcase I fitted it to a fixture made of a 90 degree block fitted on a flat plate clamped in the chuck and additionally secured with a long stud  through the main spindle.This has the advantage that planing and boring of the cylinder hole can be done in one operation. I made a  drill jig  for the cylinder boltholes which can be used for the crankcase, cylinder barrel and cylinder head.If small inaccuracies occur ( which are very likely) they will be all the same in the mating parts so assembly will present no problems.
I used camgear parts from the mockup  to fit on the front end.
3 mm bolts for the cylinder assembly turned out to be a bit lumpy so I will use 2,5 mm ones for the actual engine. 
So foar, so good.. In the meantime, I have been working on a rotating table for the camring which is a major headache for me but I will show wha t ||I have made in a separate post.
For now, it' s holiday time so I will continue the work on the 0,8 Edwards in August or so .

_Jos_


Failure is always an option      _Mythbusters_


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## josodl1953 (Dec 10, 2017)

Now it's been a year or so since I started preparations for the build of the downsized Edwards Radial 5 so , with the snow falling down in Holland, it's time to give  an update of the things I've been doing the past year. I have been making jigs, fixtures, templates ,wooden test pieces and for all, a lot of re-calculating dimensions with the help of an Excel sheet for the downzizing and the conversion to metric.
By far the biggest headache was the fabrication of the camring which required an accurate index disc.  I started withe the purchase of a rotating table to fit on the cross-slide of my lathe after removal of the toolpost. First I tried printing a tiing disc and gluing it to a 2 mm steel disc but the printing quality was far too inaccurate to mak this work. Browsing through a drawer with old stuff I found a meccano gear with 120 teeth. I made a construction on the rotating table  with a spring-loaded holding pin to keep the gear in place. On top of the gear the disc was fitted. The holes were drilled in three different pitch circle diameters otherwise the holes would be too close together. So I found myself drilling 360 1mm holes. A tedious job but someone has to do it....


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## Mechanicboy (Dec 10, 2017)

Engine built in wood, exciting to see if it was possible to run a motor made of wood.  

Smart to make parts in wood and try to sample before everything is made in metals.


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## josodl1953 (Dec 10, 2017)

So, after the drilling was complete, I had to find a way  to mark the index holes in such a way that  the chances of making mistakes are minimal, bearing inmind that a small mistake could ruin hours of work to make a blank for the camring. I had a lump of nice steel, 42CrMo4, 80 mm dia.,  used in marine propulsion systems. But with no fancy bandsaw available, I had to cut some grooves with the parting tool after reducing the diameter. Then I drilled a row of holes in this grooves and cut off the remaining material with a handsaw.

I developed a system with colours marking the degrees on the index disc.
These colours correspond with colours on the lift chart.

To rotate the disc I used a worm gear ( Yes, Meccano again) which fitted on the gear previously used for indexing. A stop was fitted on the base of the  rotating table . I used an 1 mm index pin on the disc , held in place by a small magnet.

There was another issue, being the need to move the cross-slide with increments of 0,01 mm. This required the use of e DRO, which I didn't have.
But I did have a digital caliper, so with a few fixtures it was bolted on to the cross- slide, and worked perfectly.

It seems common practise to use a woodruff key cutter fot the machining of the camring but these cutters are notoriously expensive. I used a standard end cutter  ( cost about 7 euro) with a recess made  with an angle grinder.
Yes, it's crude method but it works!  I first practised on a bronze ring to get the hang of it, an then  the real thing. It needed some smoothening but in the end the first item of tis build was completed.


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## Pat1311 (Dec 17, 2017)

Hi Jos,

Very interesting project,

Quiet an enterprise building this engine without a mill,you have my respect.

I'm currently about a month in a radial build myself so thats another dutch radial build.

I'm having an attempt on building the 7 cylinder radial from Volker Jung,all metric plans.
After contemplating on the edwards 5 I discarded them being to complicated to scale up or down to converting them to metric.

Later this week I will start a build log of my attempt on the 7 cylinder radial on this forum.

There is currently a guy on the dutch modelbouwforum who is in the completion fase of building the edwards five with several modifications.

I wish you much succes in this build and I'm going to follow all your progress.

groeten uit Eindhoven


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## petertha (Dec 17, 2017)

Pat1311 said:


> I'm having an attempt on building the 7 cylinder radial from Volker Jung,all metric plans.


 
Off topic, but hope to see your build pics & also providing link of same engine in case you hadn't seen it. http://philsradial.blogspot.ca/


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## josodl1953 (Dec 18, 2017)

Thanks Pat1311, I 'll check out the modelbouwforum. Converting to metric is quite a job but I took a year to do it. If you do it bit by bit it is'nt that hard , ideal for those moments too short to get into the workshop......

Jos


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## Pat1311 (Dec 28, 2017)

petertha said:


> Off topic, but hope to see your build pics & also providing link of same engine in case you hadn't seen it. http://philsradial.blogspot.ca/



Sorry offtopic again...

Thank you for the info.

I've read his blog and his engine is really a beauty,he's a bit of a CNC wizzard too.
Only I think he's building the nine cylinder version.


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## petertha (Dec 28, 2017)

sorry meant to say same engine designer


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## josodl1953 (Dec 30, 2017)

So, with the camring finished at last, it was time to take on the bigger parts.
As I mentioned earlier, I re-designed the crankcase  so it would be made in two pieces. There are different reasons do do so.First of all, the material I had is a hollow bushing,being a rejected part of the  recoil shock absorber  of a M109 howitzer I took home when I was working as a QA engineer at a company which  overhauled military equipment some 25 years ago. Also, it was easier to machine the bearing fittings for the crankshaft and idler bearings on a separate 
 part. And, if I mess up the bearing housings it would not be necessary to make a new crankcase, only a new bearing cover.
A year ago I made a fixture for machining the flat sides of the crankcase . I practised on a wooden  model and now I could find out if it worked out on metal as well, which it did. I did not know what kind of aluminium is was but by machining it gave a magnificent bright gloss....great stuff, that.
After drilling with my drilling jig, I made the bearing cover and the idler assy. For fitting and checking the mesh of the gears, I used the dummy crankshaft I used in the wooden mockup and a dummy cam housing I made from a stack of perspex rings bolted together.


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## josodl1953 (Feb 3, 2018)

Now with the crankcase done is was time to get on the biggest chunk of metal in this build: the cam housing. Once again I used  a rejected-M109-hydraulic-recoil-shock-absorber-part ( are you still with me?) .The diameter was some 12 mm. more than needed which was OK because I wanted to make the cam follower guides longer the the original design so that the cross loads on the cam followers were more evenly spread, and to reduce oil leaking. Downside on this was that it needed additional milling and  ,in turn, the inevitable fixtures.

Turning the inside was pretty straightforward. The challenge was to drill the cam follower holes evenly spaced. After machining the inside I made two grooves marking the axial position of the cam follower holes.For the radial position I made a device consisting of a ring fitting exactly on the mating surface with the crankcase. On this ring I made a disc fitted with a steel bracket. The disc could be fixed on the ring with a scew. On the ring  I made a mark, and also  on the cam housing. The edge of the bracket was set on 72 degrees and along this edge a second mark was made on the cam housing.
Working around the circumference of the cam housing I made five marks.If the last mark was not exactly in the same position as the startng mark I adjusted the bracket and started all over again until all marks were evenly spaced. After that, I made punch marks where the radial marks crossed the earlier machined grooves. Then is was just a matter of drilling and reaming, everything all pretty basic.

Next challende was milling the cam follower slots at the inside. First I needed a way to fix the cam housing on the cross-slide of the lathe. From the scrap box I found a piece of 90 degree consruction steel which I fitted on the cross-slide . To make sure that is was perfectly flat I made a cutting device from an old core of a speaker( again, from the scrap box) and a 90 degree cutter bolted on is. Using the lowest possible RPM of the Emco which is 100 RPM  I planed the steel. After drilling and tapping, the cam housing could be mounted .Slot milling was carried out with a small disc mill fitted on a home made mandrel.

At this point, the crankcase came into the picture. Cam follower holes were aligned withe the cylinder holes  and holes for fixing the crankcase to the cam housing were match drilled and tapped.

With the critical operations done, the rest of the machining consisted of removing excess material. First the outer diameters, leaving a ring where the cam followers are located. After that I used the milling ficture to roughly remove the material between the cam followers. For the finish machining I made a rotating feed device consisting of a spindle, crank, pickup bracket and hinge blocks. I made  five M5 holes at the front of the cam housing to which a hinge block was attached . These holes  disappeared after finish machining.

With all the machining done I think the part looks rather nice.. 

Jos


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## bazmak (Feb 3, 2018)

Ingeneous and excerlent workmanship using what you have and not what you
would like to have.Considering the level of expertice required for this project
and your obvious skill it amazes me that you have attemped  such a difficult project without a mill.You have my admiration


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## josodl1953 (Feb 6, 2018)

Thanks Bazmak, I have been doing milling operations on a lathe for about forty years so once you get used to it thing become a lot easier. It only takes more work in making fixtures  etc. but I like challenges like that.

Jos


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## josodl1953 (Mar 24, 2018)

With the big lumps, crankcase and camhousing, complete, it was time to focus on the core of the machine, the crankshaft.
Single throw crankshafts have been used for centuries in man-powered machines until James Watt used it for the first mechanical powered rotating machine.
The one-side supported crankshaft is basically a simple part. The big trick is to get the crankpin hole parallel to the shaft centerline. In order to make the work on the lathe I fitted a thick cast-iron plate ( which was a rejected pneumatic cylinder cover)together with a U-shaped alu profile on the cross-slide of the lathe.The thickness of the plate and the profile was exactly enough to fit without clearance underneath the pre-machined crankshaft between the centers of the lathe. After that, I clamped the crankshaft onto the base plate an so , after releasing the tailstock, I had a perfectly aligned crankshaft. I only had to move the cross-slide the required distance to obtain the correct stroke of the engine  . Drilling and reaming took less than a quarter of an hour( much less than it took to prepare the baseplate and clamp) and the I had a perfect clankpin hole.
To determine the length of the various diameters I first made a dummy crankshaft of scrap aluminium.After that, it was a matter of turning, measuring, polishing  maesuring etc. to obtain the correct bearing fit.
Milling the crankweb was done  on the toolpost with the mill in the chuck.

After completing the crankshaft with propdriver and spinner I could not resist the temptation to fit everything  on a stand, with the prop, to see what it looks like.

So far, so good.....


"Failure is always an option" _Mythbusters_


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## josodl1953 (Jun 3, 2018)

Next step, moving outward from the crankshaft there are master and link rods. Conrods are basically  a piece of metal with parallel holes in it For the link rods, I clamped a piece of alu on my angle plate fitted on the cross-slide of my lathe and drilled/reamed the holes .Finishing was  the way sculptors do: just remove the material you don't want...
The master rod was of course a bit more work. The centre hole was turnes to achieve the correct  needle bearing fit. After that, the  rest of the drilling/reaming was done- again- on the angle plate. To mill the slot for the link rods I fitted the master  rod on the toolpost, shimmed to botain the correct height. Since the thickness of the master rod was a bit oversize, I could correct small deviations  to ensure the slot was exactly in the middle.

Well, on to the next step: pistons, liners and barrels.  Yet another challenge....


Failure is always an option     _  Mythbusters




















_


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## josodl1953 (Sep 15, 2018)

Next  in this build I started with the cylinder heads. First  the combustion chambers. Since the conical shape is hard to measure I made a gauge  to check the correct depth. Afther that, the holes were drilled with the help of my thrusty drill jig.




After drilling, then came the tricky bit: plug and valve holes. Having no milling facilities, I made a fixture
to drill and turn the holes on the lathe, see the previous post. Befor the actual drilling , I made a small punchmark 


 with a center drill to see if the setup was correct. After thet I could drill and turn the hole. This was bigger than the original Edwards design because I chose for valve cages. Because the depth of the valve cage chamber is hard to measure against the curved surfaace of the combustion chamber I made a plug gauge to check both depth and diameter  of the chamber.






Now this build is 80% of the origininal design but one dimension remains unchanged: the glow plug hole.
To check if there is no unwanted interference between pug and valve cage holes I made a plastic model. Having done that, it seemed that there were no problems.



With all holes complete, I went on to the slots for the rocker arm brackets. Again, I made a fixture ( there is no  end in making fixtures..) fitted on the toolpost. This served for both  driilng of the mounting hole and milling of the slot.






Next, the head fins had to be milled. I made the fins slightly wider to provide more support surface for the rocker  brackets.
I did this with the help of my low-cost DRO   to get the required distance between the cooling fins. Milling with a circular millis no big deal, only is is very messy, is produces a kind of aluminium mud all over the place.
Following this, I made the flat mounting surfaces for in and exhaust flanges withe a rotating tool in the chuck.


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## propclock (Sep 16, 2018)

I have heard the expression , don't use a lathe as a mill,
or your mill as a lathe. Obviously, an uninformed expression.
Very interesting to see your lathe as a mill set ups. 
Very clever to use the preexisting gears. 
Thanks for a very informative build.


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## josodl1953 (Sep 21, 2018)

With the top fins complete, I considered the use of glow plug caps.  I purchased 90 degree caps which made it necessary  to cut away  a notch for the  cap.  After the messy head fin milling I gave the head a ultrasonic cleanup.  It is amazing how much muck   this process removes , it looked much brighter afterwards.


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## josodl1953 (Sep 21, 2018)

I have been thinking a lot about the use of valve cages in this design. The originla dsign without separate valve guides and seatings was no option for me.  The valve guides sticking out on top of the cylinderhead were an obstacle for the milling of the cooling fins. On top of that, I used  free-cutting aluminium  which is not as wear-resistant as the recommended 7075-T6 alloy. With valve cages, however, there is only a narrow edge between the valve seat and the port,see sketch. So I will drill the ports a bit higher to provide more sealing surface between cage and cylinder head.




  Then there was the fitting issue. Exhaust valves have a hard life.  After they are heated up during the exhaust stroke they have to get rid of the heat. This is partly achieved by cooling of the fresh mixture during intake and compression and by transferring heat to the valve seat when the valve is closed. The valve seat in turn must transfer the heat to the material of the cylinderhead. I have been considering the use of epoxy to get a gas-tight seal between cage and head  . This might  work for short demo runs but I intend to use this engine in a R/C plane ( if it delivers enough power....)  which will cause a considerable thermal load on exhaust valves and seatings. So I think a press fit will be the best choice.  n interfenence fit of 0,02 mm seemde a good idea  so I made a test cage and a piece of alu bar stock in which I made a chamber just like in the cylinder head. With  some pressing tools I made the fitting went well so I went on with the 0,02 interference in mind.



For the cage material there were several options.  There is , of course, cast iron, phosphorous bronze, and aluminium bronze. Phosporous bronze, so I have heard, is difficult to machine, CI seemed a bit brittle to withstand the pressing forces. Aluminium bronze, however, is easy to machine and is also used for valve guides in "real"engines. I manages to get hold on a length of 1 m 10 mm dia. I t didn't come cheap, 50 euros incl VAT but now I have enough material for this and possible future projects...
Because not all valve cage chambers were exactly the same I had to measure them, record the diameter and make all cages to size for each induvidual cage chamber.



So I ended up with this. Next phase: press fitting them.

To be continued..

I did not fail.. I just found 10.000 things that didn't work     _Thomas Edison_


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## Mechanicboy (Sep 21, 2018)

_Use Loctite 5770 High Temperature Thread Sealant instead epoxy + press fit.  I prefer  valve cage of bronce + valve of stainless steel , last very well._

_Loctite 5770 High Temperature Thread Sealant works as a lubricant to mount valve cage into cylinder head and keep gas tight when locktite is hardened._


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## josodl1953 (Sep 23, 2018)

Thanks Jens, I keep it in mind. I wonder what type of bronze you are referring to. Usual bronze contains tin which, because of is low melting point, makes the bronze less resistant to heat.
Nice place Bergen, by the wat. Been there once..


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## Mechanicboy (Sep 23, 2018)

Alloy material is the melting temperature of the tin no problem as it is mixed into copper that has a high melting temperature and then bronze has a slightly lower melting temperature than pure copper. Valve cage receives cooling via the cylinder head.

I used common bronze who are available in Norway either it's bronze or aluminiumbronze.  Abration no problem.

Nice to hear from you about Bergen


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## josodl1953 (Sep 23, 2018)

For the pressing operation I made a pair of tools to properly support the cage and cylinderhead.





I had once,  a long time ago, salvaged an old press from the scrapheap of a metal testing laboratory. It cam on handy for this opeation, with the help of a hydraulic car jack.

All went rather well, some cages needed mor force to install than others but in the end all were in place. Looks rather nice..







So far so good. Next: drilling of intake and exhaust ports.


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## josodl1953 (Oct 25, 2018)

Because I wanted as mich space between the ports and the valve seat I calculated that 7 mm would be a good value.  To test this I took  a pair of wooden cylinder heads I made for the mockup at the start of this project. I made aluminium valve guides, pressed them in ad drilled the ports which turned out to be rather well. The drill slightly touched the valve guides but I do not thik this is a big problem so I carried on with the "real "heads.





 Next step was drilling and tapping of the inlet and exhaust flange mounting holes.  I did this with yet another drilling jig.






So,with the most important operations on the cylinder heads complete, I only had to cut the side cooling fins. Normally this would be done  with a sawmill but iI preferred to do i by turnig with a parting tool.  To fit the head in the chuck I made a fixture  on which I could mount the head in four different positions. A bit elaborate , but it does the job  ant the result war satisfactory.


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## josodl1953 (Nov 10, 2018)

Meet Butch, he is my purrrrring prroject superrvisorrr.




He keeps me company while I am busy in my workshop.....

I have been considering the design of the  valve retainer and decided that it was beyond my abilities to make such a tiny cone and the spli in two equal halves... Instead, I adopten the retainer design that Terry Mayhugh used for his quarter scale Merlin . Only I made the C-  retainer from  1 mm sheet steel instead of turning and milling it from bar stock and parting them off.  I found a piece of 4130 steel - heaven knows where is came from..- which seemd a pretty good quality. 
I drilled the holes first, them cut them  loose. The square pieces where then turned on a mandrel. The slots where made using  a grinding disc on the Dremel.




The valve springs were a bit of a headache. At first I looked for commercial springs but I could not find the correct size.
Making them myself  was a problem because  getting the correct pitch by hand was almost impossible. Material was no problem because I had a coil of spirng wire of the correct thickness hanging around ( literally!) in my workshop for many years. Th bsolution was electric copper installation wire. I nhad the correct thickness to fit in between the coils of the spring wire. So I made a mandrel and a retainer for both the copper and the spring wire. Setting the lathe at it lowest speed and using the handle operated belt tensioner of the lathe  as a clutch I was able to make the springs.


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## petertha (Nov 10, 2018)

Radial I'm building has this sort of spring keeper arrangement. Uses a commercial groove retainer and a machined part. Maybe will provide some ideas.


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## josodl1953 (Nov 11, 2018)

Looks nice Peter. Do ypu have a thread of this build?


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## petertha (Nov 11, 2018)

Thanks. Yes I'm going to start a build thread hopefully soon. I'll backtrack with the pictures I have saved & carry on with making the 5 cylinder assemblies which I will be commencing his winter. I had a busy non-machining summer & just acquired a new milling machine recently so shop is still in upheaval as I get it set up & re-settled in for winter metalworking again.

I was just looking at the Edwards head for other reasons the other day for a different reason. Now I see the tapered cones being referenced. Maybe other Edwards builders have some better direct insight to that aspect of design & can comment. The Ohrdorf parts aren't difficult to make but it does tie into dimensional issues of the spring itself (Length, max/min OD & ID)... so collectively spring force & action movement. IE. there may be some latitude to modify the design, but there may also be constraints depending what parts are already machined.


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## bazmak (Nov 11, 2018)

Nothing wrong with using a lathe as a mill if your prepared to accept the inconvenience and additional time needed for setup and changing setup etc


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## josodl1953 (Nov 16, 2018)

Yes, that is VERY true. I spent a lot of time fabricating  jigs, fixtures, gages etc. 

Peter, I considered possible dimensional issues. Before fabricating an assembly, I always make prototypes from scrap material to check interaction of various parts.  In case of the valve train, I found out that I needed longer valve stems which in turn lead to longer rocker brackets.  But since I had to recalculate the whole engine design  beacuse of the metric conversion and the downsizing this was only a minor issue .

This is how my cylinder head assembly looks like:


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## petertha (Nov 16, 2018)

Coming along nice. Sheesh, you are converting imperial engine to metric units and I am converting metric engine to my inch for my machining equipment!

When you pressed your valve cages in, you mentioned some required a bit more force. Did you end up using an adhesive like Loctite or is it an interference fit? Were the 45-deg valve contact faces cut in after the cages were pressed in or existed beforehand or ? I'm curious about any distortion or sealing of the valve. But maybe that part of build is still coming.


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## Chiptosser (Nov 17, 2018)

fantastic!    You Sir, are very patient and  persistent.
It is great to see what can be done, With the equipment that you have a available (unavailable) to undertake a project like this .
Great Work!


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## JohnBDownunder (Nov 17, 2018)

Great build thread that I have just read from Pg1 to here. Informative and to the point by a jig maker extraordinaire showing patience and ingenuity. Thank you for posting and I trust we get to see a finished, running engine when you are satisfied with the result. 
Congrats,
John B


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## josodl1953 (Nov 20, 2018)

Thank you for your comments.
Peter, I used  interference fits ( 0,01-0,02 mm) . Using Loctite would be an easier option but  I was worried about the heat transfer between the valve seats and the cylinder head  if there would be a thin layer of Loctite between them. This would probably not a problem for short demo runs but I intend to use this engine on a R/C plane. Internal dimensions  ( valve guide, transfer and valve seat) were machined in one operation to ensure perfect alignment.  I don't know yet if the valve seats are distorted during pressing in because I have not lapped the valves yet so wish me luck.....

Jos


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## Raviv (Nov 22, 2018)

great work!
i am trying to take a similar root designing my own radial engine.
it is recommended that you take a cross cut to the wooden mock-up that you did in order to understand how close the ports actually are.
since i am designing my engine in CAD, and printing it using my 3D printer, its easier to have an understanding on how the parts actually integrates with each other.
learnt a lot from your post so far, thanks.


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## josodl1953 (Nov 22, 2018)

I made a plastic model as you can see in a previous post, this is also helpful.


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## josodl1953 (Dec 11, 2018)

Proceeding with the rocker brackets, I had to make  a drill jig for the bolthole because there is very little room for error. The hole dia is 2,5 mm,  the thickness is 5 mm so there is only  1,25 mm material left on both sides of the hole. The jig consists of 5 parts,  two spacers, one block with the drilling hole, and  two sideplates held together with  six  2 mm Allen bolts and nuts.



Milling the slot and drilling and reaming of the pivot shaft called for some fixtures  .. as usual ..

















For grinding the C-clip grooves in the rocker pivot pin I use my home made toolpost grinder.


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## josodl1953 (Dec 11, 2018)

Fabricating the rocker arms was a bit more complicated. Harvesting material from a slice of what appeared a sample of a thick-walled aluminium tube involved milling, drilling and good old elbow steam sawing. Only the sawblade didn't make it to the end  ... tough stuff, that..









Drilling of the holes for pivot pin, rocker button and adjusting screw involved making a.... drill jig.





After drilling, it eas just a matter of removing excess material by several  milling and turning operations, pics are self-explanatory.


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## josodl1953 (Dec 24, 2018)

With  the valve train complete, I went on with the cylinder liners and barrels.  I cut the cooling fins with the barrel fitted on a mandrel, using


 a parting tool.

Turning the liners was pretty straightforward, so no pictures. I used a light shrink fit of about 0,02 mm so after fitting them in the barrels I had to  rework some of the bores to avoid the piston from seizing up at TDC.






Looks rather nice....

Merry Christmas everyone!


Jos


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## DiegoVV (Jan 1, 2019)

josodl1953 said:


> With  the valve train complete, I went on with the cylinder liners and barrels. I cut the cooling fins with the barrel fitted on a mandrel, usingView attachment 106365
> a parting tool.
> 
> Turning the liners was pretty straightforward, so no pictures. I used a light shrink fit of about 0,02 mm so after fitting them in the barrels I had to  rework some of the bores to avoid the piston from seizing up at TDC.
> ...


Congratulation Jos for this beautiful exercise of mechanical art. 
Your posts showing us how an entire engine is built using only a lathe are the demonstration that determination and know how are by far more important than owning a ton of equipment. I am really enjoying this thread.

I hope to start soon an Edwards radial build but converted into metric. Wish me luck, I´ll need it. hehe


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## josodl1953 (Jan 4, 2019)

Hi Diego, I used an Excel sheet for the metric conversion, one sheet for each part... comes in very handy!

Jos


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## jacobball2000 (Jan 5, 2019)

If you use the same set up as Mister Edwards original design from the 1980,s. I would have to still use the distributor system for the glow plugs to save on battery life.


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## petertha (Jan 5, 2019)

jacobball2000 said:


> If you use the same set up as Mister Edwards original design from the 1980,s. I would have to still use the distributor system for the glow plugs to save on battery life.



Can you please elaborate on this. Are there plans or schematic that Edwards developed? I've seen someone scratch built systems but I no longer have the web link. There are also commercial units as well but I'm not entirely clear what they do. I always thought it was more about pulsing to preserve glow plug element while keeping them lit vs. battery capacity in 'always on' mode. Battery capacity is actually pretty cheap these days. If this discussion goes on a detour, I am happy to re-post elsewhere. I'm sure its been discussed before.

http://www.sonictronics.com/xcart/product.php?productid=16210&cat=308&page=1
http://www.sonictronics.com/xcart/home.php?cat=308


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## jacobball2000 (Jan 5, 2019)

I came up with this idea when I seen the first 5 cylinder radial engine that was using glow plugs. I would have just ran a normal distributor system and just run a hot wire from the glow plug battery system to the distributor. I haven,t seen any thing on the web just something I was thinking of. I would say look up the old full size 5 cylinder engine and copy them.


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## petertha (Jan 5, 2019)

So you mean something like a mechanical distributor but its basically closing the circuit and lighting up a glow plug? What I am confused by is you made reference to Edwards original design & I have not seen a system like that. This brings up an interesting point. When would you actually tim ethe plug to come on? Its not a spark. On a conventional glow engine, you hook up the driver plug, get the engine running & that's it, It runs on its own. The fuel, compression, glow wire, timing... all kind of take care of perpetuating the glow for the next combustion cycle. Some folks use on board glow to simply the hookup, for example multiple cylinders especially if they are under teh cowl etc. And some guys will add on board glow kind of as a precautionary measure like when they are idling. Although I can confidently say I have never found the need for that in 2S or 4S, upright or inverted engine.

Here is how this fellow did his 7 cylinder.
http://philsradial.blogspot.com/#!/2013/02/glowplug-driver.html


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## jacobball2000 (Jan 6, 2019)

My bad. When I first seen His design I thought it was using spark plugs.  Only to find out they were glow plugs. I was thinking at the time to run the glow plugs as if it was under a distributor saving on the battery and glow plug life. I been trying to find the old sigh where it showed the hole distributor system including the gear train set up. What I remember the gears were 8, 12, 24 and one other one but can,t remember what it was. If I can find it I will post it on here. Look up Morton 5 cylinder radial.


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## jacobball2000 (Jan 6, 2019)

After Re-looking at The Morton M5 Radial engine I believe that,s the road I might go down. http://modelenginenews.org/~modeng74/m5/m5.html   This is the orignal engine I found and the eb sigh.


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## tornitore45 (Jan 6, 2019)

Hi folks, I am a late comer to this thread but I am in the process to try to download the plans, unsuccessfully so far.
I see a concern about powering the glow plug.  From my day flying control line I can tell the plugs are powered only during start up. After the engine is running full throttle, the combustion  and a catalytic reaction between platinum and alcohol keep them hot.  There may be a concern at low RPM. In such case rather than a pulser to supply a reduced current a simple relay can insert switching converter or a resistor is lower efficiency is not objectionable. The main advantage is to wire all plugs with a ring, eliminate the 5 individual wires from each plug and have only one wire to process.


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## jacobball2000 (Jan 6, 2019)

When I first seen this Web sigh.  I thought of Edward,s engine and him using glow plugs. But half to keep power to the glow plugs to keep them hot. But if you use the timing and distributor system from the Morton engine. You can power the glow plugs when needed. Saving on battery life and glow plug life. You won,t need the point system. Making the distributor a mechanical switch.


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## josodl1953 (Jan 8, 2019)

I found this pictures of Forrest's own engine on his Polikarpov biplane. Ik looks very much like he was using spark plugs, on the side view  you can see  a cylindrical part on the rear of the engine, this might be the distributor but it would require a major design change because normally the inlet manifold is fitted there.


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## jacobball2000 (Jan 8, 2019)

I see where the intake manifold is. I bet it is fuel injection the engine looks new. But I am wondering if he is using a crank position censer?


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## petertha (Jan 9, 2019)

I remember reading he made several design changes over time. This link shows one of the later iterations. Not sure if thats the same one in the Polikarpov, does kind of look like. It wiring harness kind of gives a hint of some kind of pickup (as opposed to  geared distributer). But the plans that are in public domain are for sure methanol glow, no distribution. Very ingenious man.

https://www.craftsmanshipmuseum.com/KnappCol.htm


_*02—Edwards 5-Cylinder Radial*, designed and built by Forest Edwards, early 1980's, L=12", W=12", H=13"

Forest Edwards builds and flies scale model airplanes and engineers miniature engines.  He has won numerous awards for his scale airplanes, engines and flying skills. In the early 1980s, Edwards designed and developed this 5-cylinder radial engine to power his 1/4-scale Fleet model airplane, based on the 1930 Fleet Biplane. He received many requests to manufacture the engine, so between 1982 and 1994, Edwards produced 30 engines. Many were installed into model airplanes and some are still being flown today.

The 5-cylinder radial burns regular gasoline, incorporates a dry sump lubrication system and produces more than six horsepower. In his last few engines, Edwards added a centrifugal advance in the distributor and a crankshaft-driven supercharger for maximum performance.  Edwards’ engines are completely machined from 7075 aircraft-grade aluminum and are perhaps the most reliable model radial engines built to date.

To see a video of how a radial engine works CLICK HERE. The link is to a YouTube.com video generated in a 3D drawing program called Autodesk Inventor. The cutaway view shows the pistons in action on a 7-cylinder radial engine so you can see how all the internal movements are related._


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## jacobball2000 (Jan 9, 2019)

If so ingenious. Why only one flight with the glow plug set up then have to do a battery recharge? The point was made.


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## petertha (Jan 9, 2019)

I'm not really clear what you are talking about jacobball2000. After designing his own 5 cylinder glow ignition engine it appears he made an additional version adapting spark ignition & gasoline fuel. Not exactly a trivial task IMO, never mind incorporating ignition plus supercharger. If you don't think that requires some skill, then you must be working on some really amazing projects I look forward to seeing.

Glow plugs do not need to be maintained 'hot' after initial starting. That is not how they work. Once lit, they perpetually glow. At least if they were set up like a conventional methanol engine. There are some exceptions, read my post #46. Some folks have added an airborne battery to come on at idle for insurance purposes. Others add a battery purely to simplify hooking up a harness to multi-cylinder engines every time to start, especially under a cowl or other constraints. Even under starting 2A/plug is a good rule of thumb. So for a few minutes of on time during starting & landing it doesn't take much of a battery to provide that capacity. I've seen many dating back to NIMH days. Now you can get 5X that capacity in a lithium cell for the same weight. But its a moot point, 99.9% of RC aircraft, car, helicopter.... do not have augmented on board glow power.


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## tornitore45 (Jan 14, 2019)

On Sheet 19, Cylinder Liner" the plans call for: "At assembly check compression ratio and adjust to 8.5 :1 by trimming top of liner as needed."

That raises questions
Why does the compression ratio need to be adjusted?
The volumetric CR is set by design, and is set by dimensions
The effective CR is a dynamic thing depending on valve timing and leak, speed and the dead volume of the measuring gauge; on small engines is nearly impossible to measure.
Exact compression ratio is what make a Glow engine fire at the right time, so what is the deal with this adjustment instruction?

I see a lot of talk about running this engine on spark, I wonder if it was the result of difficulties with the Glow version.  Any info on Glow running versions?


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## mu38&Bg# (Jan 14, 2019)

It probably means the design did not compensate for the varying compression ratio due to the master/slave rod arrangement used in most radial engines. This results in differing compression ratios (as well as valve and ignition) in each cylinder.


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## tornitore45 (Jan 14, 2019)

Soon after my post I calculated the compression ratio based on the original plans I have.  PDF file drawn by Robert Sigler.
The CR for the cylinder associated to the master crank results to be 12.8.
Trimming the liner is only going to increase the CR, will never reduce it to 8.5.
I am not very familiar with the motion geometry in a master crank with satellites con rods but gut tells me is further from harmonic motion and it may even result in a reduced stroke for all other cylinders but the master cylinder will still have a much higher CR than called for.
According to my calculations the space left between the combustion chamber and the piston at TDC is 0.082.
The shape of the piston head has no effect on the CR as long as it matches the combustion chamber.


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## petertha (Jan 14, 2019)

The Edwards engine has a master rod geometry with link rod crankpin holes phased at equal 72 deg (360/5=72). So if the link rods + pistons + liner deck are identical, it will result in slightly different CR on various cylinders. This is generally not desirable from a tuning standpoint especially on glow. So you have some choices. Either you modify the angular geometry of the master rod crankpin holes to achieve equal CR (this has been discussed on the forum). Or you modify the top end (piston + liner) to achieve this. Edwards elected the latter. There are pros & cons to each method. Sometimes there are other issues like rod angle requiring cutting of the skirts so it’s not necessarily straightforward or confined to CR.

It is customary in glow engines to see some variation in CR, or maybe a better way to say it – at least not to paint yourself in a corner & have some ability to alter CR. The Edwards presumed pure methanol fuel & separate lubrication oil pump. Most glow engines are a premix of methanol, varying % of nitromethane & oil pre-mix (castor, synthetic or blend). Now throw in different kinds of glow plugs meaning different wire sizes which have different heat properties… Collectively it’s kind of a recipe of what works best for the application. Sometimes there are trade-offs especially when it comes to how well it starts or idles vs. running.

Converting a methanol/glow engine to gasoline is nothing new. Kits & commercial engines have been doing it for years. 
https://www.ch-ignitions.com/?SID=09b364f7b7a3ed14fe933e2c11f1fdce
At minimum you may need to modify the CR to something more optimal to gasoline, so that has been discussed. The glow plug is replaced with a miniature spark plug. The timing & energy are typically magnetic pickup dedicated solid state black box modules respectively. Of course multi-cylinder spark conversions necessitates specific firing order so that is a different black box. There are kit & commercial versions, but not that many examples of those who have converted their own. 

Classic distributors, points & coils are seen on shop made multi-cylinder engines which in itself is amazing at this reduced scale. But they are not exactly easy to make or compact or low weight such that they lend themselves to becoming power plants for airborne in RC models. I can’t say for certain if the Edwards was contemplated entirely for flight duty but there certainly examples of his design in working models & of course his inroads towards commercialization. Modern buy-off-shelf methanol radials like OS Engines look & operate on very similar principles. When you see ignition or gasoline versions, they are typically dedicated solid state ignition modules. If a home made engine will not see flight duty, I suppose that lends itself to more options to accommodate the ancillary ignition equipment, but I think is still remarkable achievement because many aspects do not 'scale' without other complications.


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## tornitore45 (Jan 14, 2019)

petertha,
I appreciate your comprehensive tutorial. This is my first glow engine an my first radial.  Although I was flying single cylinder glow in the '60 and know the CR is critical in glow engines I never had to consider the factors since I bought a FOX 35 Stunt and flew, and flew and flew.
What worries me now is the high compression ratio of the master rod cylinder that calculates to 12.8. Minor variation due to the geometry won't come close to the 8.5 specified.
While increasing the CR is  easy, reducing it is not. It may need to move the wrist pin (new piston) or cutting the cone on the top.
At this point I like to hear from anyone that has built and run a glow version of this engine.


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## Mechanicboy (Jan 14, 2019)

tornitore45 said:


> While increasing the CR is  easy, reducing it is not. It may need to move the wrist pin (new piston) or cutting the cone on the top.
> At this point I like to hear from anyone that has built and run a glow version of this engine.



Compression ratio is determined by volume of combustion camber + volume of cylinder volume. 

Thick cylinder head gasket = lower compression ratio and vice versa.  Use syringe with fluid to measure the volume via the spark-/glow plug hole in the combustion camber with piston on TDC and calculate the compression ratio.  The important: All piston stroke and bore must be same in all the cylinders then the correct compression ratio will be easy to adjust with cylinder gasket in various thickness due the volume of combustion camber is never 100% exact in all the cylinder heads when you are calculating the compression ratio and selecting the correct thikness of cylinder head gasket to get same measure of compression ratio in all the cylinders.


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## petertha (Jan 14, 2019)

I haven't worked out the volumetrics myself, but just confirming - are you saying you calculate minimum 12.8 on the MR by using the full liner lip thickness (0.175") semi recessed in the head where it shows 0.060"? If 12.8 is correct, that does seem suspiciously high. The open hole portion below the glow plug will add a bit of head volume & possibly same with flat facet valves but would depend on how they are seated. The best way to know in advance of building is CAD model / calculation which I could do.


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## Mechanicboy (Jan 15, 2019)

See at the assembled drawings of cylinder and cylinder head, there is not cylinder head gasket who means the cylinder liner must be adjusted in height of cylinder on lathe then the engine get correct compression ratio.  The alternative is the cylinder is lowered and adjust with thickness of cylinder head  gasket and get correct compression ratio.


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## Glorfindel (Jan 15, 2019)

To have 8.5:1, the lips must be .150"

Other cylinders are within 0.002" of strokes vs the main rod.


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## josodl1953 (Jan 15, 2019)

It is interesting to see how discussions develop on a subject. Even more surprising is the fact that I came across the C/R and timing issue  myself in the past days. With most of the parts complete, I made a test fitting  with  master and  link rods and found a lower C/R with the link rod cylinders compared with the master rod cylinder. I wonder what would be the effect of altering  the position of the link rod holes in the master rod, bearing in mind that this is a proven design and that  7 and 9-cylinder radials also have equally spaced link rod pins .I am also considering to adjust the  C/R  by adapting the height of the piston rather than trimming the upper end of the liner.  I always adapt the part that is easiest to make to the part that is more complicated , and in this case the easy part ( for me) is the piston.

I'd like to see your comments.

Jos


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## Glorfindel (Jan 15, 2019)

Here is how i did it.

In my cad soft (CatiaV5) i extracted surfaces of cyl, piston top and head dome.

I generated a volume for tdc and bdc.

You see the volume at bottom left, so i adjuated the lips of the sleeve to get exactly 8.5:1. I did it on the master rod.


The other pic is the "trace" of a poi t on top of each pistons for 1 cycle, so it guve me the exact stroke of each pistons. 

As you can see, they are wihtin 0.002", so no big deal.

Hope this helped.


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## petertha (Jan 15, 2019)

Trimming the thickness of the upper lip of the cylinder liner means the head would now sit at a lower position relative to the piston TDC position and therefore would increase CR. This has the identical effect as removing head gaskets. The cylinder is not lowered and there is no other change to the piston / rod throw geometry. I always assumed the Edwards lip thickness was sized to yield a conservative CR let’s say 7.0 for example. Now the builder’s job is to trim the appropriate thickness of each liner lip to achieve a constant number across all cylinders 8.5 for example. If someone wants 8.2 or 9.4 that’s fine, it’s the same methodology. The issue that conflicts with this assumption is that you are calculating 12.x MINIMUM and it can only increase by trimming. So that’s why I am asking how you derived that number because it seems too high.

The other thing to recognize over & above this is – because he chose to phase the master rod / link rod holes equal 72-deg, that inherently results in unequal CR across cylinders purely by motion geometry of the link rods. So he is ‘fixing’ 2 issues simultaneously, achieving the desired CR to some target value AND also making them equal across cylinders. By contrast in other radials, the master rod has angular positions on +/- either side of 72-deg depending on the cylinder number so geometrically the CR’s are equal. There are 2 ways to skin the cat.


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## petertha (Jan 15, 2019)

Glorfindel said:


> To have 8.5:1, the lips must be .150"
> .



I didn't see your CAD computation until after my post #67. This is exactly what I was  wondering. So you are computing essentially what I was suggesting  - that 0.175" lip corresponds to some lower CR, say 7.X And by trimming to 0.150" you get CR = 8.5.  And the suggested CR of 12.x does not make sense, some error somewhere?


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## Glorfindel (Jan 15, 2019)

petertha said:


> I didn't see your CAD computation until after my post #67. This is exactly what I was  wondering. So you are computing essentially what I was suggesting  - that 0.175" lip corresponds to some lower CR, say 7.X And by trimming to 0.150" you get CR = 8.5.  And the suggested CR of 12.x does not make sense, some error somewhere?


0.175 = 7.25:1

On my drawings, it say 8.5:1

There is only 0.002" difference in strokes between cylinders, i dont think that will change CR that munch one from another.


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## petertha (Jan 15, 2019)

Yup, your plans show the exact same as snip I posted in #62. I believe your CAD derived numbers & resultant CR's looks right. If we want to get into even deeper detail, we factor valve facets & any hole volume beneath the glow plug. That's why it this is harder to do with paper & pencil. Maybe Edwards intended the liner lip trim to be final step using syringe & liquid.

Years ago I had a spreadsheet that calculated CR's by inputting master & link rod geometry. I seem to recall about 8% variation in CR from highest to lowest cylinder but possibly that was a different 5-cyl design. CR does vary between cyl #1, 2 & 3 with equal (72-deg) phasing. Did you extend each to TDC to measure that .002" or just one of them? Maybe the spreadsheet had a bug because 0.002 / 0.150 is only about 1.3%difference on basis of bore diameter, so I agree its negligible. Good discussion! Thanks for the validation.


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## Glorfindel (Jan 15, 2019)

If you look at my third pics, i traced every pistons srtoke. They are all within 0.002" from the master rod.

I'll simulate what 0.002" mean in our ratio tomorrow.


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## petertha (Jan 15, 2019)

Ah, I see that now. #1 is 0.966 (2 x crank pin radius, check). You displaced each piston to extremity along liner axis. #3 and #4 are 0.968, so maximum difference is 0.002" 
#2 and #5 are 0.967" so 0.001" difference. Looks good to me. 

Kind of interesting - similar displacement 5-cylinder radial engine I am building (Ohrndorff) has compensated master rod. I checked the link rod pin angles against a published graphical method used to equalize TDC position for same CR & they match. As you can see the resultant angles are quite different +/- nominal 72-deg. But I never have went back to determine the actual CR effect if they were at 72-deg. It does vary by combination of stroke & link rod dimensions, just assumed it was more. Like I said it was based on spreadsheet, but something tells me something was a bit fishy about how the bottom of stroke was determined for each cylinder.


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## Glorfindel (Jan 16, 2019)

I'm happy that i saw that thread, i was not aware that we can have different strokes vs angle.

And sorry if i jumped in without introducing myself, i will do it in the right place.


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## tornitore45 (Jan 16, 2019)

So many sub subject here

1) the conical shape of the piston and combustion chamber has no effect on CR as long as they match. The volume removed by the piston cone is equal to the volume added by the conical head.

2) There are small unaccounted volumes, such as the hole in the Glow Plug and its filament, the valves heads not seating flush with head.
It must be noted that the plug thread is o.25" and the Plug thread is 0.25" minus the gasket, not a big error there.

3) Everyone has his own preferred method to change the CR: Gasket Thickness, Changing the length of the Liner Lip, making a new piston. I may add my method which is to change the depth of the 0.060 bored section in the head.   Its diameter and concentricity are not critical and is easy to re-chuck the head and bore a little deeper. YMMV

4) We have established that a Master Rod arrangement with equally spaced pins does not yield the same stroke on all pistons, is a fact of geometry. All depends from the interrelation of Stroke, Master Rod length,  satellite rods length and position of the pins on the Master rod.
Someone has calculated that, for this specific design, the strokes are just about as big as normal machining tolerances.   A perfectionist may move the location of the pins a few thousand in or out radially and overcome that concern.  Anybody that built an engine has realized how little the piston moves by rotating the shaft a few degree back and forth at the TDC and BDC,  is a fact that the cosine unction is very flat at the crests.

5) My biggest concern is none of the above, forgive me for restating, my concern is that according to my calculations (I have been wrong before in 1989, I though I made an error) the CR is already higher than specified and trimming the lip is not a solution.

I am attaching the spreadsheet where I did the calculations, if I made an error, please point it out. We all need to be settled on the CR.
The spreadsheet should be clear but if you have a question shoot on the thread or a PM.

Turns out I can not attach a spreadsheet so here is a TXT file, I tried to display the formulas used to go from place to place.


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## tornitore45 (Jan 16, 2019)

Alert, I may be wrong but it looks like there is a confusion about the dimension to use in calculating the CR.

On sheet 5 of the plans,  the crankcase is shown with the sump on top and cylinder #1 at the bottom.  You will notice the 10-32 threaded hole for the Idles Shaft position orient the drawing view.

The dimension to be used in calculating the CR is the 1.860, NOT the 1.925.
Using the 1.925 the CR turns out to be 7.6.  If that was the case then by changing the lip to 0.15 would set the CR = 8.9 much closer to the spec. But is wrong.

In reality reducing the lip to 0.15 would raise the CR to 18.1


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## Glorfindel (Jan 16, 2019)

tornitore45 said:


> Alert, I may be wrong but it looks like there is a confusion about the dimension to use in calculating the CR.
> 
> On sheet 5 of the plans,  the crankcase is shown with the sump on top and cylinder #1 at the bottom.  You will notice the 10-32 threaded hole for the Idles Shaft position orient the drawing view.
> 
> ...



I will check your excell sheet tomorrow.

My model is acurate and it doenst make mistakes calculating the volumes.

There is something wrong. I will double check everything tomorrow.


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## petertha (Jan 16, 2019)

Sorry I can’t quite follow your calculations.

To compute CR you require two volumes. Vc or clearance volume or combustion chamber ‘squish volume’ that occurs above the piston when at TDC. And Vd or displaced volume of the piston when at BDC, which is controlled by bore area times the stroke length. Then CR = (Vd + Vc) / Vc. What are those two respective volumes on your calculation?

 I don’t quite see where you might be determining the cone volume element for either the piston or the head, but maybe something happening behind the scenes? I would be looking for something like Vol = PI * R^2 * H / 3 (where R = bore/2 and H = height of cone). For example if the bore is 0.945” and angle is 20 deg, I get H = 0.172” H = tan(20) * R  vs  your  cone height = .162???

I can’t quite determine what is what in your calculation but you refer to liner length. That doesn’t factor into anything, only the stroke and in this configuration the lip thickness which is the head rests on & influences Vc

There is no prerequisite that the piston crown shape must ‘match’ the head chamber like cone within a cone. Obviously they can’t mechanically interfere with one another but many piston/chamber permutations are seen between flat, domed, non-symmetrical lobes. I think these features come into play to control burn front & and intake/exhaust flow, but that’s a separate discussion. Two engines can have identical CR and Vc but completely different piston crown & combustion chamber shapes.


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## Glorfindel (Jan 16, 2019)

.


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## petertha (Jan 16, 2019)

Sometimes different terminology is used for static CR & I am guilty too. Here is a pictorial with their  corresponding wording.
https://www.rbracing-rsr.com/compstaticcalc.html


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## Glorfindel (Jan 16, 2019)

petertha said:


> Sometimes different terminology is used for static CR & I am guilty too. Here is a pictorial with their  corresponding wording.
> https://www.rbracing-rsr.com/compstaticcalc.html


Not sure anymore. My cad prog already add vc+ vb when the piston is at BDC.

I will simply check squish to see if im good.

I dont have my 3d model at home.


it would be nice if someone who have already built the engine would give us some info.


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## Glorfindel (Jan 16, 2019)

tornitore45 said:


> So many sub subject here
> 
> 1) the conical shape of the piston and combustion chamber has no effect on CR as long as they match. The volume removed by the piston cone is equal to the volume added by the conical head.
> 
> ...




I checked your file and i saw that you have a squish of 0.080"??? That's a very big squish. I would guess about 0.040'' as a good starting point


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## Glorfindel (Jan 16, 2019)

Please guys, post your compressed (cv) volume, the uncompressed volume (uv) and the squish you got from your calculation.

With lips at 0.150'' :

uv: 0.765ci
cv: 0.09ci
Squish:

CR: 765/0.09= 8.5

I didnt calculate the volumes, i asked the cad prog what was those volumes at tdc and btc directly in the assambly, so i cant see how my numbers can be wrong.


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## tornitore45 (Jan 17, 2019)

We are all talking about static or volumetric CR, just geometry neglecting leaks, and valves overlap.
There is no need to screw around with volumes, the cross section area does not change and get canceled out. CR = 1 + Stroke/ Gap    the gap is the residual distance between piston and roof of the combustion chamber at TDC. The conical piston head has no effect.
THE VOLUME REMOVED BY THE PISTON CONE IS EXACTLY EQUAL TO THE VOLUME ADDED BY THE CONICAL CAVITY IN THE HEAD.

Think of cutting off the cone on top of the piston and gluing into the combustion chamber cavity, the residual volume is not changing.
Considering volumes does noting but add potential error sources in the calculations.


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## tornitore45 (Jan 17, 2019)

I appreciate all the theoretical disquisitions about combustion chamber and piston head shapes, BUT let's focus on the problem at hand: The Edwards Radial 5.

Has anyone noticed that the piston cone has the same Diameter and Angle as the Head cavity? They match to each other like hand and glove, there is no volume between EXCEPT for the gap or Deck Height like someone like to call it.
There is no Head Gasket in the design or the calculations, let's live that out.
We all understand the head gasket reduces the CR.


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## tornitore45 (Jan 17, 2019)

Glorfindel 
If I use 0.15" for the liner lip and 1.925" for the distance between axis and crankcase face I obtain exactly your numbers  CR: 765/0.09= 8.5

BUT the 1.925" dimension is not the one to be used here, that dimension defines the Oil Sump location.
Look carefully at the drawing, it is upside down.  Cylinder #1 is at the bottom.
The big hole for the liner should tell, the small 0.25" hole at the bottom drains the oil in the sump (neglecting gravity).  The 10/32 threaded hole next to the rear bearing should tell you about the drawing orientation when compared to the cut out view on sheet 2

The correct dimension to use is 1.86"

There is no point in debating math and method when we use different data.
Everybody here knows how to calculate a fkng CR, let's focus on reading the drawing correctly.


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## tornitore45 (Jan 17, 2019)

Petertha, you caught a couple of error, thanks.
I used the cosine instead of the tangent to calculate the cone height, my bad.
But I have not used that data in the CR calculation for reasons amply explained above.
I listed the Liner Length because I thought I may needed it but as you pointed out has no bearing on CR and I never used that data in the calculations.

If I could have posted the actual spreadsheet you would have been able to see the errors , the source of them and the fact that fortunately had no effect on CR accuracy.


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## Glorfindel (Jan 17, 2019)

My model should be accurate and you're 100% sure of your calculation.

I will setup a couples of drawing to show my dimentions in case of an error on my part.

I actually hope that i made the 1.925 vs 1.86 error!!

 We are doomed!! ;-) 

Worst case is i will add shims if my CR is too high. I can cut anything at any thickness on our wire edm.

I'll double check anyway with your excell sheet.

Thx for taking the time to help me.


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## tornitore45 (Jan 17, 2019)

A 0.036" head gasket will fix the problem
If the engine is not yet built adding 0.036 to the liner lip or boring the head to 0.024 instead of 0.060 is a solution


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## Glorfindel (Jan 17, 2019)

I dont want to hijack this thread, i will make a new one about CR.


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## mu38&Bg# (Jan 17, 2019)

I just checked, because I found it odd that there would be an error for decades which nobody found. I get ~8.6:1 with a .15" lip.


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## mu38&Bg# (Jan 17, 2019)

Tornitore, M in your calculation does not come into play.


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## Glorfindel (Jan 17, 2019)

dieselpilot said:


> I just checked, because I found it odd that there would be an error for decades which nobody found. I get ~8.6:1 with a .15" lip.


I just did it "by hand" and i still get the same results.


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## petertha (Jan 17, 2019)

Does this help shed light? I agree the 1.860 dimension is the one to be using because it pertains to the #1 cylinder. 1.925 does not factor into this aspect. Its an unfortunate choice of view projection because we are looking for #1 cylinder to be 'on top'. But you can see it has the liner hole 'on the bottom'. 

In any event the 1.860" is only an intermediate dimension to attach the cylinder on top of & then the liner within resting on the lip and then the head on top of lip. Behind all this completely independently is master rod relative to crankpin throw & then piston superimposed onto MR. I'm guessing Glorfindel has these individual parts assembled within CAD using mates & determining resultant volumes at TDC & BDC. Do we have agreement on input dimensions?


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## tornitore45 (Jan 17, 2019)

Mea culpa, mea culpa, mea culpa. I am still trying to clean all the eggs splattered on my face.

As pointed out, the dimension of the 0.060 x  1.176 dia in the head has no bearing on the CR, I goofed.
For some insane reason I saw it as lowering the head and made a wrong inference.

My calculations agree 99.8% with  Glorfindel.  My plans show the dimension for the fins to be 1.415 versus 1.417. Nothing to stress about.

Once again I apologize for sending you on wild goose chase.


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## Glorfindel (Jan 17, 2019)

tornitore45 said:


> Mea culpa, mea culpa, mea culpa. I am still trying to clean all the eggs splattered on my face.
> 
> As pointed out, the dimension of the 0.060 x  1.176 dia in the head has no bearing on the CR, I goofed.
> For some insane reason I saw it as lowering the head and made a wrong inference.
> ...



No problem, it made me double check everything ;-)

When i did the cylinder, i checked the lenght after the third one and i got 1.417", so i did all the remaining one at 1.417 ;-)


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## tornitore45 (Jan 18, 2019)

Let's change the subject
It was mentioned that the con rods tend to wear out.
I am surprised because AL 2024 is the usual recommended for tough parts like con rods and pistons and many commercial engines are not sleeved on the little end.

So I was looking at a possible Oilite bushing
https://www.mcmaster.com/6658k725
This is specified as 11o lbs of radial force and 120 RPM which is a fraction  of the stress in the engine

Should one think of solid bronze, or forget the entire idea on the assumption that 2024 alloy is good enough.

Waddayoutink?

Something to consider
While the master crank pin actually revolves in the master rod big end, wrist pins and link rod big end never complete a turn but simply rock back and forth.


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## petertha (Jan 18, 2019)

Almost every RC engine I have seen has bronze bushings run against hardened steel wrist pin or crank pin. Maybe more importantly, have some combination of angled holes or slits for lubrication. OTOH nobody has ever talked about master or link rod failure using straight aluminum of sufficient strength alloy. I think with radials of this scale the remaining wall thickness is already quite constrained. Not so much the piston end but bottom end to fit within the master rod slot & pin. Probably the best approach is like how Terry.M  & others did their engines: Loctite a solid bronze rod in the aluminum, then drill/ream to final dimension so it can be made thin & vs. turning an annular ring & fitting that into the rod. I’m not sure what the lubricity & wear properties of high strength alloy aluminum is to bronze, but maybe beyond practical life expectancy?


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## tornitore45 (Jan 18, 2019)

[QUOTEAlmost every RC engine I have seen has bronze bushings run against hardened steel wrist pin or crank pin][/QUOTE]
I am old enough to have owned the smaller engine 0.15. 0.29 and 0.35 that you could buy (imported from USA and Japan) for the equivalent of a few dollars and those had no bushing. We ran them for hours every weekend from age 12 until girls started to become interesting, and I can't remember wearing out (the engine).
Modern High Tech commercial engine are targeted to a different clientele, guys that do not flinch to lay down a G for a top toy, they expect to outlast them by a couple of generations.   Nothing wrong with that.
On the other hand, things are different. I am not building the engine to fly, I want to build a "good" engine to show with pride and when I am gone I want he fellow that open the engine not to say "He could have done better but choose to cut corners".
In conclusion I think I will light press a solid bronze pellet and drill and ream.
The bushing can not move axially once installed.


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## petertha (Jan 18, 2019)

Sounds like you answered your own question. I don't think solid bronze link rods or master rod is practical. Depending on the alloy, it will be lower strength & significantly more weight which means increased rotational & reciprocating mass, more counterweight, stronger crankpin, bearings etc. For example SAE660 bronze has tensile of 20ksi, density 8.9 g/cc (other flavors increased strength & lower weight). By comparison 7075 aluminum is 73ksi, density 2.8 g/cc


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## josodl1953 (Jan 18, 2019)

I must remember you guys that this thread was about building an Edwards radial 5. However interesting your discussions are, maybe you should start a new thread in the department"General engine discussions".

Well,on wit the fabrication of pistons.
Some 30 years ago I was using Picco P90 engines in my racing boats but parts were hard to get. Especially ABC piston/liner sets were a problem. When the wrist pin securing circlips went their own way due to worn out grooves there was always damage to piston, liner, or both. Sometimes the liner was still in good condition but separate pistons were also not available.
Now the material for pistons was hard to get. These ABC systems ( Aluminium piston ,Brass liner, Chromium plated) required piston materials withe the same rate of expansion as the liner because of the tight fit ( piston rings were not used).
I found a big discarded diesel piston on the scrapyard of a diesel engineering company. The material of this piston prroved to be just the right stuff to make pistons from, which I have been doing till I quit model boat racing a few years ago.
There isn't much left of the piston but...


 there was still enough to make pistons for the Edwards as they have a smaller bore. The material was harvested by slicing off sections of the donor piston    . Drilling holes in a circle provided blanks for the Edwards pistons. A threaded hole in the middle provided a fixing point for a mandrel because there was insufficient length to clamp it in the chuck.



After fitting the blank to the mandrel it was necessary to machine  the OD and the piston ring groove in one operation because it was impossible to refit the piston in exact the same position.


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## propclock (Jan 18, 2019)

Great Tip!  Now where do I find used Submarine Diesel piston?


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## Mechanicboy (Jan 19, 2019)

propclock said:


> Great Tip!  Now where do I find used Submarine Diesel piston?



You can melt down the old piston and pour in the steel pipe who are larger than piston diameter. Let it cool down , then the cast  aluminium bar will fall out of steel pipe.  See what i converted the OS MAX 61 to a pure diesel engine in the picture series when i created the piston and cylinder.


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## josodl1953 (Jan 24, 2019)

It was a marine diesel piston, not a submarine diesel...I only used this material because I had it still laying around. Only if you are looking for material for a ringless piston in an chromium plated brass cilinder it is worth the effort. If you are using piston rings you might as well use any good quality aluminium,preferably the type specified on the drawing.   

Jos.


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## josodl1953 (Jan 28, 2019)

After drilling the inside of the piston I proceeded wit the the wrist pin holes. Now I don't drill them on the drill press because I don't trust the perpendicularity. I have been drilling  wrist pin holes with a fixture on the lathe ever since I started making pistons. I leave the pistons a little bit longer  so they  fit snugly in the fixture. The top of the piston is turned to size later on. The advantage of this method is, apart from the perpendicularity, that  a groove  for a retainer clip can be made, not necessary in this case,  but indispensable  with, for instance , .90 CMB two-stroke engines.




Next step:  milling out the inside, again with a fixture on the toolpost.





To finalize the piston, I turned the top, measuring the height with a template I made from an old speedboat rudder.


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## josodl1953 (Mar 16, 2019)

With most of the parts complete now, it is time  to give the small bits some thought.






I have been thinking a lot about the fabrication of the cam followers.  The cylindrical part, the stem,  is the first to be machined but the part is to be clamped on this tiny bit in order to machine the hammer-shaped end. The stem is only 3 mm thick so I wondered if it would be strong enough to withstand the machining forces. As usual, the proof of the pudding is in the eating, so I started off with a number of hardened dowel pins I had so lang in my scrap box I forgot where the came from. First they had to be annealed to make them machineable ( red hot with a blow torch). After that, I milled a flat surface on the side  to prevent is from moving while machining the hammer  end . The stem is having a semi-hemispherical end contrary  to the original design which shows a hollow end of the cam follower. I did this because  is difficult to make a semi- hemispherical hole in a 3 mm shaft. After the stems were finished the hammer ends were machined   in a fixture  which went surprisingly well.

So, another step closer to the end of the project.

Jos


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## josodl1953 (Apr 2, 2019)

Some more tiny bits..15 intake  and exhaust flanges have to be  made. First drilling the holes for the tubing, then drilling the fastening holen with the same drill jig I used for the cylinder heads. After that, cutting them  apart the old fashioned way: a saw and some elbow steam. The periphery was machined on the lathe and the finishing touch... Dremel work.


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## josodl1953 (Apr 2, 2019)

One of the last parts to be machined  is the inlet manifold . After  turning,  planing and drilling  of the inlet holes was done on the toolpost ( as usual). But I used the wrong end mill  for the O-ring chamber  ( 12 mm instead of 10 mm) so I had to make another one ....


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## tornitore45 (Apr 2, 2019)

To make the poppet I got a 1/8" x 1/4" piece of O1 steel.   Held in the 4 jaws I turned the round tail.
Then made a fixture with a hole and a slot to accept the flat part protruding just enough to round it.  A thin Slit is sank deeper in the slot to make the fixture flexible enough to clamp the head.  A  center mark was sunk where the center of the radius is to be located.   Clamped the fixture and the part with the center mark coaxial with the rotary table.  The flat head is clamped on all its extension, then head and fixture are rounded.


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## josodl1953 (Apr 3, 2019)

Sounds complicated...do you have pictures of this operation?

Jos


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## tornitore45 (Apr 3, 2019)

Jos I know you do not have a mill/rotary table so my method may not be usefulo to you.
Have no pictures. Perhaps is my explanation that makes it look complicated.
The basic idea when dealing with a part that is difficult to hold, orient or register is to make a cradle. A fixture nearly a matching cavity. Then add some method of clamping with set screws or allowing the fixture to collapse like a collet by slitting on a suitable plane.


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## josodl1953 (Apr 4, 2019)

Yes, I get your point. But is seems difficult to me to get the flat part   perfectly in line with the stem , that is, with my humble machining faclities..

Jos.


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## josodl1953 (May 2, 2019)

I was having some piping problems lately. First, after pain in my chhest, they found out  at the hospital that my coronary arteries were a bit clogged up, not severely, just  bit.  This problem was solved by installing two stents, a job of three-quarters of an hour, amazing what they can do. Next day I went home and after a week's rest or so I went on with the intake tubes of the Edwards. I tried bending of brass tube (after heating up to make it soft) withe a home made tube bender but the first attempts were, well, less then satsifactory , to say the least. It was  important to me to maintain the inner diameter of the tubing to get maximum power  out of the engine, bearing in mind that  , if all goes well, this engine will be used on a R/C plane. The brass being difficult to bend, I changed to aluminium tubing. This material being easier to bend, it also contributes to weight reduction togetyher with alu intake flanges ( with an extension, to be fitted with epoxy).



The first attempt withe alu tubing, filled with sand, gave a better result but still not good.


  Some wrinkles on the inside of the  115 degree bend developed which is not good for optimal gas flow.  Also I found it hard to get the tube bent in the right shape. So, I made  dummy intake pipe frome 3 mm wire. With this dummy, I made a  sturdy  fitting jig  so that I could bend the tube is shape  avoiding putting stress on precious engine parts. 






Filling the the tube with molten lead  prior to bending  gave, at last, the required result.












 So, another job done. The to-do-list is getting shorter and shorter.....




I love it when a plan comes together....._John "Hannibal"Smith --- The A-Team_


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## davidyat (May 3, 2019)

I haven't tried it yet, Cerrobend. It has a melting point of 158 degrees. You can melt it in boiling water in a container, get it into the tubing you want to bend, bend it and then put into boiling water again and I guess it flows out of the tubing.
Grasshopper


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## Shopgeezer (May 3, 2019)

Neat. Where do you get it?


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## davidyat (May 3, 2019)

Some places I've found:
eBay:   https://www.ebay.com/itm/Cerrobend-...018121?hash=item43d5d07849:g:FIoAAOxyc2pTaiqe

IMS Supply: https://www.industrialmetalsupply.com/Products/specialty-metals/cerro-bend#1

or: http://csalloys.com/products-cerrobend-alloy.html

or: https://shop.boltonmetalproducts.com/Low-Melting-Temperature-Alloys_c3.htm

Grasshopper


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## Cogsy (May 3, 2019)

I've used cerrobend at it works just as advertised. One tip is to coat the inside of the tubes with a little oil (I used vegetable oil) before you fill with cerrobend, so the tubing can 'slide'  over the cerrobend as it is bent. Once the tube is bent I just flash the torch over the tube and the cerro falls out quickly.


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## josodl1953 (May 4, 2019)

Interesting stuff. However, I had the lead already available and it worked for me.

I did the exhaust tubes  too, was a lot easier with only one bend.
Finishing and polishing them took most of the time...

Jos


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## stackerjack (May 4, 2019)

Hi Guys,
Sorry to interrupt this thread, but I am unable to start a new conversation. Each time I try I get the message "Invalid recipient"
Can anyone help please?
Jack


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## stackerjack (May 4, 2019)

O.K. I might as well post it here:
Several people on this site have been searching for plans, originally drawn by Strictly I.C.
I have every copy of this magazine and will probably not use most of the plans.
Is it breaking any laws/rules for me to sell these plans to others? I did buy them in the first instance.
Jack


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## bobden72 (May 4, 2019)

Cerrobend works great have used it many times, don't forget to anneal the mettle to be bent first or it could split or wrinkle.


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## petertha (May 4, 2019)

stackerjack said:


> I have every copy of this magazine and will probably not use most of the plans. Is it breaking any laws/rules for me to sell these plans to others? I did buy them in the first instance. Jack



If you look on the inside front cover page of SIC magazine I think it spells out the rights reserved aspect. I cant say that the plans show this or if so, consistently over the years. I didnt check very exhaustivley, just grabbed a few off the shelf. I think you could sell your magazine which includes the plans. I guess you could sell your plans removed from the magazine. Don't really think its right to copy the plans & sell them, legally or morally.


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## josodl1953 (May 5, 2019)

Gentlemen,
May I remind you that this thread is about building the Edwards Radial 5. Questions, remarks and discussions not concerning this engine or parts thereof should be posted in another thread.

Thank you for your consideration.

Jos


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## Letsflyj3 (May 6, 2019)

josodl1953 said:


> Interesting stuff. However, I had the lead already available and it worked for me.
> 
> I did the exhaust tubes  too, was a lot easier with only one bend.
> Finishing and polishing them took most of the time...
> ...


Hi Jos  WHere did you get th eplans for the Radial engine your work looks great.  Thanks in advance for the info.


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## josodl1953 (May 6, 2019)

Hi Letsfly, 
I downloaded the plans from the internet, they were free at the time ( 2016). They come as aPDF  file. Just google"Forest Edwards Radial 5" and the file should pop up  somewhere.  I converted mine to metric and reduced  to 80% of the original , with some modifications, See the start of this thread.

If you can't find them I can post the original file here.

Jos


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## josodl1953 (May 10, 2019)

Last parts to be machined of this build were the piston rings. I followed  the directions of the drawing being:
- turning a tube  with the approximate dimensions of the rings
- milling a slot  over the full length of the tube
- clamping in the chuck till the slot is closed
- turning final diameters
- parting off
I found that it is necessary to have the part  outside the chuck should be as short as possible otherwise the slot will not be fully closed. In my case this was approximately 6 mm. The width of the parting tool and the ring both being 1 mm, I could make 3 rings in one go. 







The drawing recommended the use of a parting cap placed over the ring to be parted off. I made one with bearings and a shaft to be fitted in the tailstock because  I was fraid the the ring and cap would fly off after parting. Now it stays put when it becomes loose.






With this help, parting off was a piece of cake.










There were - of course - a few issues . The inner diameter was initially too big but I  went on, just for practice.
So, with corrected ID I went on to find out that the thickness was 0,1 mm undersize. So I made the following ones slightly oversize, to  be ground  to the correct  dimension when fitting them to the pistons.


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## tornitore45 (May 11, 2019)

I suppose the 1/2 hole threaded was in the original junk box piece used to make the cap.
What is keeping the cap from backing off?  Does it stay put just by friction?


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## josodl1953 (May 11, 2019)

Yes  Mauro, that's right. It  was an old cover of a rejected pneumatic cylinder. By accident, the 1/2 hole came in really handy for removing the ring from the cap. The bearings have a strong fit on the shaft so  no  additional fixings are needed to prevent it from backing off.

 So this  is the result of 2,5 years of work, not hard work, just work..




Jos


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## tornitore45 (May 11, 2019)

Very close to making some noise!


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## dethrow55 (May 12, 2019)

tomitore 45 i see your in austin tx im here in el paso. many years ago i worked on mopac loop 1 austin. beautiful town


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## josodl1953 (Jun 20, 2019)

On assembly I foud that the roundness of the piston rings was .. well... less than satisfactory. So I made s set with a slight ( 0,2 mm ) oversize and machined the final OD on a mandrel. This gave better results but there were still a few that were not good, but it seems a common problem with home made  piston rings: a fair amount does not meet the requirements. If you need 10 pieces, make 20...




















Jos


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## josodl1953 (Jun 24, 2019)

After final assembly I spent the past weeks  building the glow plug control panel. For 5 plugs one needs about 15 amps which is more than 


 the the average starting battery can provide . Luckily I had two of them , one of 9.5 Ah and one of 10,5 Ah so if I put them parallel they should be up to the job. I made switches for each individual plug, together with an ammeter so I could tets each plug without taking it off the engine.

A test with 5 plugs in a test fixture  proved satisfactory.















With temperatures in the Netherlands now soaring above 30 degrees Celcius  I think I'll postpone the final installation till the temperatures drop a little......

Taking it easy now......

Jos


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## tornitore45 (Jun 25, 2019)

Good idea about the ability to know each plug is good.  I am not to that point yet but will experiment with looping the wire a few turns and use a hall effect sensor to turn an LED.
Nothing wrong with switches and Ampmeter but I like to see 5 LED in a pentagonal pattern.
Another idea I was bouncing around was to use a 6V battery and PWM control to adjest the voltage as the battery change. Rather than long wires I plan to make a ring held by the display stand feeding each plug from it.  My engine will live on the display stand not on an airplane. Currently on extended vacation away from the shop, will resume in the fall.


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## gunner312 (Jun 25, 2019)

I just printed out a copy of the Edwards 5 drawings. I'm wondering, I have 7 pages and they seem to be incomplete, such as not raw materials list. It  looks like a fairly difficult project but not unsurmountable. Any suggestions on the build?


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## petertha (Jun 25, 2019)

The PDF drawings I downloaded some time ago, maybe year 2014? [A08a] are 40 pages in total. They are not dated so I cant tell you if there have been other revisions.


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## petertha (Jun 25, 2019)

There are newer type single glow plug igniters like this one. 
https://hobbyking.com/en_us/hobbykingr-6-24v-lipoly-glow-plug-igniter.html?___store=en_us
It must use something like a voltage regulator because it allows for a wide range of elevated input voltage (6-24v) yet delivers at requisite glow plug voltage & current draw. This would be a perfect match for common, inexpensive RC Lipo/LiFe cells which can deliver substantial current, no problem. The issue is one would have to get X number of these for multi-cylinder engines. Or figure out what the circuitry is doing. I have a feeling this is what some of the home made boards are doing. Going to have to cross this bridge myself one day.


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## tornitore45 (Jun 26, 2019)

Peter the device on the link you posted would work in principle but is not practical. I can see a problem with 5 of these sticking out around the engine and having to remove them behind a 20"  propeller.   I like the idea to have a single point of  connect/disconnect fairly distant from the propeller even considering that I do not plan to mount it on a model airplane.
The ideal approach I am thinking is to use a 12V lead acid battery and a 5 phases PWM.
2/12 = 16%    5x16%= 80%  therefore the battery is delivering nearly DC current at 3A 
A quick calculation shows Five 10 uH inductors, MOSFET and Shottky diodes plus some small stuff for control should do it.


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## petertha (Jun 26, 2019)

Hi Mauro. I agree. I was just referring to circuit board / regulator aspect, not the big spring clip connector. That connector is just conventionally used for temporary starting, then removed for flight. Its actually extra long to recah inside cowlings etc. There are much neater miniature connections that just clip onto the glow plug stem, easily home made. I know I have seen public domain glow plug igniter circuits for multi-cylinder engines, just don't have my links handy. Look forward to what you come up with. My point in mentioning the LiPo battery is they are very compact, high energy density & have no issues delivering at high current. Even a low grade these days might be 25C, so for example 2500 maH pack could deliver 25 * 2.5 = 62 amps continuous. We would never need that of course. I know some of the mini gel cell 12v batteries are getting better but generally they are comparatively low 'C' so you need larger capacity, which means a big bulky cell. But LiPo are different nominal voltage per cell (typically 3.7-4.0). So 1S = 4.0v, 2S = 8.0v etc. LiFe are a bit lower nominal per cell but still too much for glow plug voltage. So that's where I see the variable input / fixed output regulator type circuits as being useful. May well be what the PWM is behind the scenes. I'm electrically challenged  For lithium batteries you also require the charger to go with it. Not a big cost these days but maybe not what you have. 12v is still such an ubiquitous standard.


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## tornitore45 (Jun 26, 2019)

Understand your point but I do not plan to be operational in the field so I have more options.
I used to design all sort of  converter for a living. I do not relish electronic home projects because I am spoiled by the availability of industrial labs. But in this case I will give it a try.


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## petertha (Jun 26, 2019)

7 cylinder driver, but its all Greek to me.
http://philsradial.blogspot.com/2013/02/glowplug-driver.html

Probably we should let Jos get back to work with his method. I know this has been discussed before on HMEM. Its kind of begging for a dedicated post.


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## josodl1953 (Jun 27, 2019)

On the parts and notes list of the Edwards it is stated that an onboard battery is recommended. I assume this applies to idling and low revving .  When this engine eventually ends up on the nose of an R/C plane the electronic devices as suggested  by you  might come in handy. For the time being, the two  2Volt lead-acid batteries seem to be up to the job.

Jos


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## tornitore45 (Jun 27, 2019)

The plugs should stay hot once the engine is revving but, as you say, is nice to have some form of assist to guarantee a slow idle.
It was an idle thought of mine back when I was flying to make a controller that kept the temperature constant by measuring the resistance of the plug when the PWM phase is off and closing the control loop on the sensed resistance.
Using a cold plug and artificially increasing the heat could possibly result is some form of advance control.   The current required should be much lower that during starting. Most likely this is just idle dreaming.


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## josodl1953 (Jun 28, 2019)

So, with everything assembled, this is what it looks like:
















The only thing that remains  ... the all-important question... Does it run?

Yes, it does... watch the video on  

Jos


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## josodl1953 (Jun 28, 2019)

Well, what next? Of course there are some loose ends to tidy up. Idling is not optimal, for the initial runs I used  new old stock plugs I got from my brother with whom I  was running R/C speedboats  a long time ago , to save the expensive 4-stroke plugs during running-in. Also I will need a collector ring for the exhaust because now oil is all over the place, especially because I run the engine a bit on the rich side. And it may be worthwile to do a bit of research on electronic devices to provide low weight  glow power.

So, it is not the end of the story but the most important milestone is reached.

Jos


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## tornitore45 (Jun 28, 2019)

Great sight.  What prop are you using and what RPM you are getting?  Granted that those values means little before break in.
What is the difference between 4 strokes plugs and 2 strokes plugs?  4 stroke should be hotter I suppose.


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## aka9950202 (Jun 28, 2019)

Weĺl done. Love your work. 

Cheers, 

Andrew in Melbourne


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## propclock (Jun 28, 2019)

Fantastic! the only thing I would change is go spark and gas.
 wonderful build post thanks for your efforts at sharing.


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## Johno1958 (Jun 28, 2019)

That engine purrs .
Cheers
John


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## Tim1974 (Jun 30, 2019)

Hay you got there I’ve been following this for so long what a inspiration well dun to you


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## josodl1953 (Jun 30, 2019)

EPILOGUE

Well, this build was a long and winding road for the past two-and-a-half year but it was worth the effort.
I hope that it encourages other " apprentice" home model engine machinists to build engines even if they do not posess fancy CNC equipment or even a mill. I made this engine only with a lathe, a drill press.. and some elbow steam. It takes a lot more time, ingenuity and perseverance if you have simple machines but hey, this is a hobby, take your time , have fun, and go for it.

I planned to go R/C  flying with this engine but before doing so it has to prove its airworthyness with respect to power, longevity and reliable throttling. Eventually it should fly a Boeing Stearman.

It should look like this






About future engine projects, I have been thinking about an Erwards Radial 9 . There are some interesting differences
between a radial 5 and a radial 9, apart from the number of cylinders of course. The camring  of the 9 has double the amount of  cam lobes (8) compared to the 5 (4). Also the camring of the 9 turns at half the speed of the 5.





I think the main dimensions of the cam housing can stay the same, probably a bigger OD of the crankcase will be needed to get enough room for 9 cylinders.

Of course there  will be ready-to-go designs for model radial 9's but this engine would be easier for me because I could use a lot of tooling  as used for the radial 5.

This is, however, is a project for the distant future. I find a flat four more appropriate as a next project.
Using the cylinder and head design of the Edwards, I came up with this.




It has a vertically split crankcase, a built-up crankshaft running in 3 ballbearings. One of the crankwebs in the middle is clamped to the middle section of the crankshaft  to enable fitting of the middle ball bearing. The camshaft is fitted in a cam housing bolted on the bottom of the crankcase and driven by gears at the backside of the engine, just like my flat twin (see avatar).  Now this is a preliminary design  so do't expect a thread on this engine before next year..... 

If you have any questions just PM me     and above all... keep the chips flying!


Jos


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## josodl1953 (Jul 2, 2019)

Mauro, I forgot to answer your question about prop and RPM.  The recommended prop for the full size Edwards is a 22-8 or 20-10 at about 6000-7000 rpm. I chose a 18-10 for my downsized version. I was so overwhelmed by the fact that the engine started right the first time that I forgot to take RPM readings. I let you know as soon as I have done the next test run.

Jos


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## WOB (Jul 2, 2019)

There is no need to separate the flat-four opposing con rods by a crank web.   They can live side by side on the same journal as is common on auto engines.  Makes a shorter, simpler crankshaft and a shorter engine.  If you make the center bearing a split bronze sleeve, you can have a one piece crank which is always better.   Also no need to have a split crankcase.    You can do it with a rear removable plate only so a total of 2 pieces for the complete crank case.






This engine illustrates what I'm saying.   It's a 4-stroke glow ignition with 1"cylinder bores.  Turns an 18-10 Zinger at 7200 RPM. It is a 2X scale-up 0f  this engine originally published in "Strictly IC" magazine:   http://www.strictlyic.com/ser01.htm

*PEEWIT*, by Eric Whittle 
          A 5.5cc, Horizontally-Opposed, 4-Cylinder, 4-Stroke, 15oz, 3 ¾ " long, 3" wide,
          Air Cooled, Glow Ignition Aero Engine.  10" X 6" prop at 8,000 RPM’s.
                         Issues: # 57, 58, 59, 60 & 61.....$8.00ea.....TOTAL: $40.00

WOB


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## josodl1953 (Jul 4, 2019)

As far as I know boxer engines always have crankpins separated 180 degrees for each set of  opposed cylinders (BMW, Beetle, Honda Goldwing). Is there a cross-section of this engine?

Jos


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## tornitore45 (Jul 4, 2019)

WOB, I suppose the PEEWIT is a 5.5cc per cylinder totaling 22 cc. Right?
It may be the next engine I build.


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## WOB (Jul 4, 2019)

tornitore45 said:


> WOB, I suppose the PEEWIT is a 5.5cc per cylinder totaling 22 cc. Right?
> It may be the next engine I build.


No, it was a total of 5.5 CC .  The original engine as published had 1/2" bores.   It was too small for my taste.   I upscaled it 2X get 1" bores,  This made the new displacement 44 CC.   Easier to build and swings a good size prop with authority.  If you build it 2X, it looks a lot like and sounds just like this:    

WOB


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## WOB (Jul 4, 2019)

josodl1953 said:


> As far as I know boxer engines always have crankpins separated 180 degrees for each set of  opposed cylinders (BMW, Beetle, Honda Goldwing). Is there a cross-section of this engine?
> 
> Jos



You are right, of course.   Don't know what I was thinking.   In my defense, it has been 20 years since I built the engine.   

The connecting rod little ends on this engine are offset slightly to allow the cylinder bores to be a little closer together than normal.  This partially compensates for the crank web thickness between journals   Sorry, I no longer have a copy of the magazine engine articles.   

WOB


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## tornitore45 (Jul 4, 2019)

I love the stand and the starter.  I would make it a 2X as well.
I am curious where did you insert the one way clutch for the starter?  I would not want to see the big gear spinning after starting.


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## WOB (Jul 4, 2019)

That is not my engine.   I was just trying to show that the 2X PEEWIT is similar to the commercial OS FF-320 and that video popped-up when I searched for OS FF-320.    I probably should have posted this: https://www.towerhobbies.com/cgi-bin/wti0001p?&I=LXBY71 
Sorry for the mix-up.

WOB


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## WOB (Jul 5, 2019)

Regarding a possible electric starter for the Peewitt, it would be easy to extend the crankshaft through the timing gear housing on the back end of the motor.  You could even use the cam shaft instead and the 2:1 gear reduction built in.  Then it would be easy to add the starter motor and over-running clutch concealed behind the motor mount backplate. 

WOB


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## tornitore45 (Jul 5, 2019)

Yap, that is the best way to do it.


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## petertha (Jul 5, 2019)

Excellent runner Jos! Congrats for your hard work & perseverance.
What is your fuel of choice right now? (like commercial RC fuel containing oil, or homebrew methanol/nitro no oil,,?)
How is the lubrication pump system working? No issues?

I'm confused by your Edwards-9 radial & Edwards flat-4. Do you mean using the same Edwards-5 cylinder components but essentially layout assembly of your own design?


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## josodl1953 (Jul 7, 2019)

Yes, Peter, that's my idea, bearing in mind that I have the tooling for the cylinder/head assambly already.
But these are just ideas, I am still miles away from actually building them.

Jos


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## josodl1953 (Jul 7, 2019)

About the fuel, it is left -over racing fuel from my model boat racing career, containing 15 % oil ( castor/synthetic 50-50) and 10% nitro. I have no lubrication pump, the cam housing contains its own oil supply, the separated crankcase receives oil from blow-by of the pistons like all commercial four-stroke model engines. Time will tell if this will provide sufficient lubrication.

Proof of the pudding...

Jos


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## Michael Rosenbauer (Nov 13, 2019)

Jos you are a son of a gun.
Chapeau you are a real home engine machinist!
Sehr gut!


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## josodl1953 (Nov 14, 2019)

Danke  schön!
I will be at an exhibition in  December where I will be demonstrating the engine, After that, I will take it apart to check for wear to see if it is fit  to be used on an R/C plane.

Jos


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## Michael Rosenbauer (Nov 15, 2019)

Sounds like plan.
Do you have the plane already?
Michael


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## josodl1953 (Nov 15, 2019)

No the plane has yet to be built. I already have downloaded plans  of a Boeing Stearman ( also known as Kaydet)  But I'm still thinking of the right size, bearing in mind that the engine is rather heavy ( almost 2 kgs) so tha plane should be not too small but not too big either because I could not measure the power of the engine. A wingspan of 1m 80 should be a feasible option and it should look a bit like this






But,like I said  before, the engine must first prove its airworthyness  before I start the construction.

Jos


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## jquevedo (Nov 15, 2019)

Check Ziroli Plans for Big scale plane plans and some building materials, I bought the Stearman PT17 plans and they are great, I'm in the process of building the 87 inch wing span version, have a 9 cylinder radial I Bult from Hodgson plans.


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## Jrcfiero (Nov 15, 2019)

How about using compressed gas?


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## petertha (Nov 15, 2019)

Some pics of Mr. Edwards handiwork, the Polikarpov with a 5-cyl variant installed. It appears Forest was equally good at building scale model air frames as he was an engine designer & machinist.
https://www.flickr.com/photos/[email protected]/sets/72157603556449257/

On a side note, does anyone have any information on his 2-cylinder supercharged engine? Was it ever written up or featured anywhere?


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## awake (Nov 15, 2019)

Wow, what a smooth running engine. Fantastic work!


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## josodl1953 (Nov 16, 2019)

jquevedo; The Ziroli plans look good but  slightly too big for my engine. Ziroli recommends from 75 to 250 cc, mine is only 30 cc.
jrcfiero: Do you mean  compressed gas engines? In the early days of powered model planes there were very small motors running on compressed CO2 from cartridges.
Peter: A few of these pictures I already found on the web but these are even more revealing.  The Polikarpov's fuselage was made of metal by the looks of it , with beautiful riveted panels.  Forest Edwards must have been a craftsman with outstanding qualities. I wonder if  he had fitted his engine with spark ignition. On the side view one can see the HT leads coming from some kind of distributor housing on the back of the engine. There are some more differences between the original engine and the design according to Robert Siglers drawings. The cooling fins of the cylinder heads of the original are slightly curved whereas the Sigler heads are flat. Also, the cam followers of the original are offset, on the Sigler drawings they are in line.

Maybe Robert has information on the supercharged twin, his email adress is on the front page of the set of drawings.


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## petertha (Nov 16, 2019)

Yes in another (RC) forum post I read, it discussed modifications Forest made to the Polikarpov engine which deviated from the builder plans. But I have also read other postings which seem more speculative & light on details. Some have used the words 'ignition system' without really defining (or maybe understanding) what that meant. The braided cables could have been for scale show purposes & conventional glow plugs used in an on-board glow mode which is common on multi-cylinder RC engines. Or he could have converted to distributor/spark  knowing his abilities & the wire shielding would have been required for RF interference. There is a distributer-ish looking can in the rear, but again was it functional or more for show? The plugs look about glow plug size but I've seen ingenious model engineers make spark plugs of that size. I'd love to know some of the details if anyone has good info. Yes, maybe Robert would be a good lead.


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## Noel Gordon (Nov 16, 2019)

Nice chat theme guys...Almost finished my Edwards 5 and I plan to install into a 100" Strikemaster using Nick 













Hi guys, a nice chat thread.. I have almost finished my Edwards 5 and I intend to install in a 100" Strikemaster using Ziroli plans which I now have.. I intend to run my radial using pump gas as Ive modded the heads to take mini spark plugs.... Slow to finish my radial because of selling our house and buying another (and I really hate the process)
















777777777777


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## Shopgeezer (Nov 17, 2019)

We have sold houses and bought new ones all our married life. Career changes, new postings, and family situations meant constant changes. I would just get my shop set up to my satisfaction and get into some projects and Bingo, off we would go again. Lathes and mills don’t like moving.  I like it even less. Moving house is awful, moving a shop is much worse. I still have projects in boxes from years ago. My current shop is my retirement dream and I’m staying put this time.


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## josodl1953 (Dec 15, 2019)

Now that the end of the 2019 is  approaching, it is time to evaluate the build of my 80% Edwards radial 5.
First of all, the positive aspect is that I got it running. A less positive point is that  I could not let it run at full power because when I did  it died slowly. I could keep it running sometimes when I took back the throttle quickly.  There was a substantial blow-by which was evident  by the amount of oil and fumes coming out of the crankcase breather. After a few runs, this oil  had a brownish colour  , possibly caused by corrosion of the cast-iron cylinder. Apart from this, compression was fairly good
 ( cold)  and ( electric) starting was no problem  ,running half throttle was fine, including very short full-throttle bursts, and attracted a lot of attention at a show last week. 

So , I decided it was time to take the engine apart   to check for wear and the suspected corrosion problem.
On removal of the rear crankcase cover and a cylinder head  the corrosion  of the cylinder was confirmed. I think   I should have been paying more attention on after-run cleaning . Nitro-containing fuels seem to be rather corrosive.






So far the things that were not so good. Positive was that there was  very little wear   on conrods . At the front side, there was the camdrive to be inspected. From the beginning, I was worried about wear on the camgears because they were not hardened.  Also there was the question of wear on the camring and followers. They were hardened  but, well, you never know..

Luckily, there was no excessive wear on any parts of the camdrive which was a relief because there are no obvious alternatives, especially for the idler gear.














I could do with  a bit less sealant on re- assembly....

Piston looks a bit brownish but no excessive scoring marks.




Cylinder head has no obvious weaer, exhaust valve is a bit darker as can be expected.





So I'll have to think about a solution for the full-throttle problem. Maybe I will have to fit second piston rings to get rid of the excessive blow-by. Another reason might be a too lean mixture but I use a carb from a 5 cc Super Tigre so I think that is not the problem. Fuel mixture has 17 % oil, does seem to be OK.

Any ideas  to solve this problem will be welcome....

Jos


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## tornitore45 (Dec 15, 2019)

Great report
My guess about dropping out at full throttle is that the carb is too small.
You are using a 5 CC engine carb for an 11 CC. There is always 1.25 cylinder in the intake phase equivalent to about a 13 CC single cylinder displacement.

I am almost finished making parts for mine, last minor fittings then I must make the display base. My engine does not fly but mount with all the accessories to start it and run it.  I plan to run the glow plugs with AC out of a transformer with 5 separate winding.  Guessing which plug is blown is not going to be fun so I have a circuit checking the individual currents.


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## petertha (Dec 15, 2019)

_About the fuel, it is left -over racing fuel from my model boat racing career, containing 15 % oil ( castor/synthetic 50-50) and 10% nitro. I have no lubrication pump, the cam housing contains its own oil supply, the separated crankcase receives oil from blow-by of the pistons like all commercial four-stroke model engines_

That's great that you are provide us real life running conditions update. The cam gears look much cleaner, do you think because it was in a separate chamber isolated from the crank case? What kind of oil did you have in there?

The corrosion looks like its concentrated around the CI liners extending out of the crankcase, quite red around the ends that protrude into the crankcase. I've seen RC engine that look like this but usually confined to many, many years of dormant storage where spent fuel is sitting in a puddle. The liner ID's are typically hard chromed but the OD & other components still non-coated steel. Methanol is a bugger for attracting moisture out of the air but I would not have expected that after a short period. Even with generous after run oil between runs I think it would be hard to get a coating on all those surfaces. And then you would have to do  good job of pre-draining before runs. The pistons & top end looks nice.

Hmmm... I have CI for my liners too, that step is coming around the corner. I am still oscillating back & forth between CI & 1144 stressproof. But so many homebuilt engines call for CI. Nobody really shows pictures like this. Do you happen to recall what alloy you used?


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## bobden72 (Dec 16, 2019)

After seeing you internals I think I will have to strip my Edwards 5 down and check it, its been six years since I saw the insides.


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## propclock (Dec 17, 2019)

Thanks for the tear down, just a thought. almost as corrosive as nitro fuel
is silicone seal. the gas it emmits for curing can be very corrosive. 
There are modern no acid silicone seals but the older ones can be nasty.
I at one time RTVd (silicone seal) a limit switch bracket to my mill. 
The following day there was a 3 " rust area around it. 
In a sealed environment( crankcase)
it could be as nasty as no after run oil. Beautiful engine.
Just my 1.414 cents worth.


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## josodl1953 (Dec 18, 2019)

Hi Mauro, 
Typically, four strokes require much smaller carbs than their two-stroke counterparts.
I looked up the recommended carb size based on the internal  dia of the Edwards manifold flange, being 0,437".
This is from the official Perry website:




Carbs this size (2100) are intended for .21 to .50 cu. in. ( 3,44 to 8,1 cc)two-strokes.  Now I downsized my engine  from the original 55 cc to 31 cc, so i don't think the size of the carb is the problem.
However, I did notice that some cylinder bolts came loose very easily so I must investigate the correct  torque for this bolts (M2,5)

Peter, 
I use outboard gearbox oil , it smells like the oil that is used in ( manual) car gearboxes and diffs and I think it is basically the same stuff.




I filled the camhousing slightly more than half with oil but I had to block the breather on top of the housing
beacuse the oil was blown out, by centrifugal force I guess.
The  camring hub has two scoops to help the  oil circulation from the outside of the camring to the inside , 
 but of course I don't know if it really works.




For corrosion prevention, I think  spraying with an anti-corrosion agent  such as WD-40 in the in take  while spinning the engine  with the electric starter would help. There is a breather in the rear crankcase cover  but if I fit another on the opposite side I can also flush the crankcase after running.




As far as the corrosion of CI is concerned: it should be best avoided but on the other hand, it is not the end of the world.
Although is does not look like this way, CI is fairly corrosion resistant. You must remember that a lot of products 
containing water  such as cisterns and drainpipes were made of CI before plastics came along, and they lasted for decades.
I used GGG 40 for the  liners and GGG60 for the rings, these are European standards, the numbers referring to the tensile strength in kgf/mm2. Hardened  and/or chromium plated cylinder liners work fine for commercial produced engines
but for  hobby/home made engines, CI  is, to my humble opinion, the best choice. It seems to me that non-hardened  steel liners are OK  for short runs but  not if a certain amount of longevity is required.

Propclock, I did not use silicon based sealer  but Hylomar, the blue non-hardening paste.  Works fine , parts are easily separated, only cleaning up requires thinner or an alcohol-based detergent.

Jos


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## tornitore45 (Dec 18, 2019)

You right, I missed the fact that the Supertigre 5CC was most probably a 2 strokes.


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## josodl1953 (Feb 7, 2020)

After a month or so working on my hibernating Honda CX 500 , I turned to the leak problem of the pistons. Compression cold is not bad, starting with an electric starter is a piece of cake, and still there is the problem of dying out at full RPM, combined with excessive blowby from the crankcase vent.  The obvious choice is to fit two piston rings, like the original.
There was no room on the existing pistons to cut an additional ring groove  so I decided to make new ones.





This is the prototype version from  mystery aluminium, a strange alloy that could only machined with oil based lubricant
such as WD-40.


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## tornitore45 (Feb 7, 2020)

> mystery aluminium


My guess is a cast alloy.
Cast alloy tend to make chips rather than strings and do not achieve the mirror finish achievable with the extruded types.


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## josodl1953 (Feb 8, 2020)

Yeah, that is what one would think but.. it is extruded bar stock. I do not know where it came from but it is very brittle.
At the start of the Edwards project I tested some alloys with a home made tensile test device. Is is just a lever with a sliding weight using test bars with a minimum diameter of 2 mm .








This was not exactly  testing methodb  according ASTM (or any standard whatsoever) but it gave me an idea which material was rubbish  and which was not.




When I tried to make a test bar of the mentioned alloy it broke before I finished it so is it really brittle.

Now I remember from the past that the German piston manufacturer Mahle  once produced an alloy with a very high silicon percentage for people who wanted to make their own pistons so that would be a possibility but then again, I haven't a clue where the stuff came from.

Anyway, I went on harvesting material form my old diesel piston which is now depleted  as far as 20 mm material is concerned.





It gave me sufficient blanks to make a new series of  pistons for the Edwards.






When I made the prototype piston I discovered that I could not measure the depth of the piston ring grooves. I made the grooves slightly smaller so I could possibly use left over rings that were rejected  because of their thickness.
So I made a pair of attachments to fit over the jaws of my digital caliper, saving me the money for an expensive groove measuring tool that I would hardly use.


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## tornitore45 (Feb 8, 2020)

Very clever accessories.
I use the same technique of "gnawing" with holes when sawing is not possible.


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## Mechanicboy (Feb 9, 2020)

The common fault when lost of compression or poor compression: The surface in piston ring groove is not smooth to keep tight against leakage. Use a tiny side rake lathe tool there you can smooth out carefully in the surface in the piston ring groove. And piston ring must be smooth in surface and have a right ring gap calculated by gap vs bore size.


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## josodl1953 (Feb 15, 2020)

Just finished 5 new two-ring pistons.



On the subject of piston rings: I wonder whether old brake cylinders could be used  to make them.





The material is cast iron and is easy to machine.  Old brake cylinders can be obtained at any scrapyard for next to nothing  ( or nothing at all if you fix your car yourself). The only  question is if the material quality is any good. Being a safety item,  it should be made of good material   ... shouldn't it?  

Any comments ?


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## Mechanicboy (Feb 16, 2020)

No problem, the cast iron in the brake cylinder is good quality. I has used brake disc who are made of cast iron to produce piston rings. My model engines has still good compresion after a lot of years.  And the cam shaft of cast iron too except the cam is too hard to machine.


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## aka9950202 (Feb 16, 2020)

I used brake cylinders to make piston rings.  As they were the only rings i have ever  made i can't say it is a good idea or not.  My engine is a runner so they do work. 

Cheers, 

Andrew in Melbourne


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## josodl1953 (Feb 16, 2020)

After measuring the wall thickness of the piston crowns I found out that they were... well, a bit thin, the thinnest measuring 1,7 mm. Whoops.... Now I can fit them in the engine and see what happens  but I'd feel more comfortable if I would know  that these pistons could withstand the pressure. Now a long time ago I made a hand operated hydraulic pressure pump, just for the fun of it. It came in handy afterwards. I helped a friend of mine who had the piston of the brake caliper of his old BMW motorbike seized up. With the pump connected, the piston came out quickly. To test the strength of the piston, I made a  thick-walled cylinder4 housing with a connection for a hydraulic pipe. The testing object was a previously rejected piston that was adapted to fit an O-ring instead of the usual piston ring .



Wall thickness   "t" of the test piston was slightly thinner, 1,6 mm.





I managed to get the pressure to 100 bar, and nothing happened.






From various sources I found out that combustion pressures in four-stroke petrol engines are about 30-40 bar. Even if the pressure in glow engines would be higher and taking in account  a reduced strength of the piston material due to high temperatures, I think I 'm am  quite safe. 

Jos


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## petertha (Feb 16, 2020)

I hadn't realized peak pressures get that high. I've seen a few generic pressure profiles like this sample plot but had not payed enough attention to the Y-axis. Amazing. The duration at that pressure spike must be very short, but it repeats often & I guess stress is stress when it comes to materials.
https://performancetrends.com/Definitions/Cylinder-Pressure.htm


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## josodl1953 (Mar 14, 2020)

With the pistons complete I went on to the piston rings. Having made the ring grooves a bit narrower I could use previously rejected rings that were too thin. This meant that the thickness had to be reduced form 1,00 mm to 0,80 mm. Doing this manually would probably result in a lame hand so I made a lapping machine using old parts form various sources.



I replaced the adjustable bicycle bearings by ordinary deep groove ball bearings. The whole thoing conssist mainly of a vertical shaft  with an excentrical shaft mounted on top of it. On this shaft there is the lapping disc mounted on two ball bearings .A retainer rod is fitted on the side of the lapping disc to prevent it from  spinning around. The rod moves between two ball bearings to reduce friction. The motion of the lapping disc is comparable with the motion of the big end of a conrod.




The ring is kept in place by a plunger-type tool, adjustable to match the thickness of the ring.



There is a ring on the lapping disc  to hold the sandpaper in place. I started with grain 100, final lapping was done with 400.


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## awake (Mar 14, 2020)

Very cool! Any chance of a video of it in action?


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## josodl1953 (Mar 15, 2020)

I'll give it a try..


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## josodl1953 (Mar 16, 2020)

This is how it works.

It sounds a bit wacky but it does the job..

Jos


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## awake (Mar 16, 2020)

Ingenious! So the sandpaper is held by both the central nut/washer and by the outer ring, right? Any tendency for the sandpaper to pull up, wrinkle, or rip?

I've long contemplated some sort of sharpening contraption using wet/dry sandpaper - that's what I use to get my chisels and planes super sharp, but currently I have to do all the motion, with the consequent danger of rounding over. Something like what you have rigged up, without the oscillating motion, and a tool rest ... hmm ...


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## josodl1953 (Mar 17, 2020)

Hi Awake, the sandpaper is held in place by the ring only, the bolt in the middle is for keeping the hollow shaft for the disc in place.


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## awake (Mar 17, 2020)

Thanks.


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## DiegoVV (May 9, 2020)

awake said:


> Ingenious! So the sandpaper is held by both the central nut/washer and by the outer ring, right? Any tendency for the sandpaper to pull up, wrinkle, or rip?
> 
> I've long contemplated some sort of sharpening contraption using wet/dry sandpaper - that's what I use to get my chisels and planes super sharp, but currently I have to do all the motion, with the consequent danger of rounding over. Something like what you have rigged up, without the oscillating motion, and a tool rest ... hmm ...


Nice job Jos!!

I have one question...What glow plugs do you use?
I am building my own Edwards radial 5 but it seems difficult to find the ones that the plans specify (Fox Long with idle bar) they seem to be really old stuff...

Thanks!!


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## Mechanicboy (May 12, 2020)

DiegoVV said:


> Nice job Jos!!
> 
> I have one question...What glow plugs do you use?
> I am building my own Edwards radial 5 but it seems difficult to find the ones that the plans specify (Fox Long with idle bar) they seem to be really old stuff...
> ...




Use OS "F" glowplug for 4 stroke engine.


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## josodl1953 (May 15, 2020)

I have the OS  F too( recommended by my model shop)  but I need the glow power on at low RPM. In the specs , an onboard battery is recommended which obviously only applies if you want to fly it. I know the idle bar plugs from my early days of C/L flying  but I 'm not sure if they are still manufactured ( not even sure if the Fox company is still in business...)

Jos


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## DiegoVV (May 16, 2020)

josodl1953 said:


> I have the OS  F too( recommended by my model shop)  but I need the glow power on at low RPM. In the specs , an onboard battery is recommended which obviously only applies if you want to fly it. I know the idle bar plugs from my early days of C/L flying  but I 'm not sure if they are still manufactured ( not even sure if the Fox company is still in business...)
> 
> Jos


Thank you Mechanic boy and Jos!! I'll use os-f. 

Another question to delete from my "one-million question
s list" about the Edwards 5.


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## DiegoVV (May 23, 2021)

Close to finish the project and now I'm debating myself between different options when thinking about the glowplug driver. What do you use? Arduino to regulate depending on rpm's, NE555 timer to provide an adjustable output, a voltage regulator to provide a constant voltage? I'm a little bit lost here.

thank you folks!


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## tornitore45 (May 23, 2021)

My engine is mounted on a display with Fuel Tank, Oil Tank and provision for powering the plugs. Is not meant to fly but is ready to run for fun.
The 5 plugs are powered by AC via a transformer, 5 isolated secondary's.   I wanted to have some control and diagnostic.  The voltage is adjustable some +/- 20%  from a nominal 1.4V. Each plug current is monitored and turn a light on. I did not want to remove the plugs to see if they are good.


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## josodl1953 (May 23, 2021)

I use two parallel  2V 9Ah gel batteries, they provide ample power for 5 plugs and make you independent form AC power sources if you want to run your engine at shows, displays and so on.





I made a control panel  with switches and an ammeter so I can swith on every individual plug , for checking .






Is is not as sophisticated as Mauro's solution , I'm not very good at electronics, but it works.


Jos


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## DiegoVV (May 23, 2021)

tornitore45 said:


> My engine is mounted on a display with Fuel Tank, Oil Tank and provision for powering the plugs. Is not meant to fly but is ready to run for fun.
> The 5 plugs are powered by AC via a transformer, 5 isolated secondary's.   I wanted to have some control and diagnostic.  The voltage is adjustable some +/- 20%  from a nominal 1.4V. Each plug current is monitored and turn a light on. I did not want to remove the plugs to see if they are good.


Nice solution!! Not a common transformer I see...Is it powered from wall socket or from a lower voltage source?


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## DiegoVV (May 23, 2021)

josodl1953 said:


> I use two parallel  2V 9Ah gel batteries, they provide ample power for 5 plugs and make you independent form AC power sources if you want to run your engine at shows, displays and so on.
> View attachment 125792
> 
> I made a control panel  with switches and an ammeter so I can swith on every individual plug , for checking .
> ...


Easy solution, I like simple solutions when possible, my only concern is blowing some plugs at 2volts. As far as I know, they are happy with voltages from 1.2 to 1.5v. How's your experience in that matter?


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## oldengineguy (May 23, 2021)

Tornitore45 :  Where do you get those batteries? They are just what I need for my Kinner 5 cyl radial. I'm in Ontario    Canada and have not had any luck finding them. Thanks Colin


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## bobden72 (May 24, 2021)

DiegoVV said:


> Close to finish the project and now I'm debating myself between different options when thinking about the glowplug driver. What do you use? Arduino to regulate depending on rpm's, NE555 timer to provide an adjustable output, a voltage regulator to provide a constant voltage? I'm a little bit lost here.
> 
> thank you folks!


My solution is simple, I just connect it to a 25amp 2 volt battery, and no problems with plugs burning out.


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## josodl1953 (May 24, 2021)

I have been using 2V batteries for glow plugs for almost 50 years and never experienced any premature glowplug blowups. I used about 20"leads to the glowplug clip to ensure a small voltage drop and ease of handling- I use them for starting speedboats. The batteries were sold by the German Graupner company but were made by Sonnenschein. They are still on sale but very expensive ,40 Euro for a 2V 10 Ah gel battery. Maybe NiMh would be a cheaper solution for people outside Europe. Furthermore, there is a German company called Rainbowtronic that produces microprocessor-controlled glowunits for radial engines, I don't know if they ship to the U.S.  I might get myself one of these if I ever put my Edwards on a plane. 

Jos


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## petertha (May 24, 2021)

Thanks for the Rainbowtronic suggestion. I wasn't aware of that company. Irritating cookie popups but whatever.
Here is a link to some of the multicylinder glow modules if anyone else is interested




__





						Onlineshop: Suchen
					






					rainbow-tronic.de
				




What's nice is they are using more commonly available Li batteries (assume because these glow systems are orientated for flying, therefore light weight). But I assume some of the glow control features are tied into RC TX-RX throttle signal so might not be a plug-n-play for a benchtop running engine





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						Description of GlowControl
					

Beschreibung GlowControl System




					rainbow-tronic.de


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## DiegoVV (May 24, 2021)

Nice find. I was not aware of Rainbowtronic. The only 5 cyl drivers I have found to this day were quite expensive, but this one seems to be more or less affordable.


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## Dragons_fire (May 24, 2021)

B&E electronics in Calgary has a couple different 2v gel cell options.  Not sure if they could ship though.


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