5 Cylinder radial (winter's project)

[gbritnell]

Hi Dave,
I have this type of pushrod on my Holt engine and they work fine so I'm hoping that they work out well on this engine. I'm sure that when I get it running there will be a few changes needed but I won't know until then. On my V-twin and 4 cylinder OHV engine I found a few things that needed modifying after they ran for awhile.
I started on the pedestal for the fuel and oil tanks today. I have been trying to locate some 1.00 square brass tubing for the tanks but haven't had much luck. If I can't find any I'll have to fabricate them.
gbritnell

 

[Deanofid]

Sure is beautiful, George. Your photography is tops, too!

 

[steamer]

".....Hi Dave,
I have this type of pushrod on my Holt engine and they work fine so I'm hoping that they work out well on this engine. I'm sure that when I get it running there will be a few changes needed but I won't know until then....."


Oh I'm sure what ever tweaks that get done will be minor! :bow:

I was wondering because the "Wallaby" uses an eccentric pivot bushing....which works very well...but is not very prototypical...I like your design far better as I've seen that approach in full size practice, but wondered about how well it scaled. Thanks!

Dave

 

[ninefinger]

Hi George,

I might have missed it but I didn't see what solution you came up with for the return oil pump versus the supply oil pump? You were thinking of adding an extra tooth to increase its capacity? Inquiring minds want to know!

Regards,

Mike

 

[gbritnell]

Hi Mike,
I had already machined the oil pump cavity in the rear cover so I couldn't modify that to take the bigger gears so for the present I put finer pitch gears with the same pitch diameter in the pressure side. I didn't calculate the volume of the negative space of the 32 DP gears as opposed to the 48 DP gears to see if it would give me what I needed but I could also go with an even smaller PD gear set in the supply side if necessary. It's one of those things that came to mind only when sitting thinking about potential design problems that it came up. I haven't looked at drawings are spoken to anyone in regard to building the bigger radials like the Hodgson etc. so I don't know how they handle it.
If worse comes to worse I'll put a shut-off valve in the feed line, crank the engine over to clear the sump of oil then turn the oil valve on prior to starting. With the finer gears they should supply less than what the scavenge pump does, even if it's only a little bit.
PS. The pressure side bolts on to the rear cover so it was just a matter of making another one that had the smaller OD for the 48 pitch gears. Attached is a PDF of the drawing to show you what I have done.
George

View attachment ENGINE RADIAL SHT 2e.pdf

 

[ninefinger]

Hi George,

Thanks for the answer, I hope it works out OK. I think you'll be OK but if not you could always try making the cavity a touch deeper and increase the gear width, or extend the cavity into the cover to take wider gears, either way you could increase the displacement quite a bit - say take the .125" gear up to .175" which would be a 40% increase.

Anyway keep the updates coming - I love seeing this kind of craftsmanship (especially on round engines).

Mike

 

[gbritnell]

I guess it's time for an update. Although it doesn't look like a lot has been done there have been many hours tied up with some changes and to the current point in the build.

I'll start off with one of the changes. When I designed the engine I had made the intake tubes so that they would be a nice slip fit into the crankcase and the head flange would bolt up to the head with enough room for a gasket. It sure looked good on paper but with no wiggle room with the pipe inserted into the crankcase there was no way of getting a good seal against the port face. I came up with several ideas but all had some sort of complication involved in keeping the parts plumb, square and in alignment for silver soldering the flange onto the pipe. The initial tubes were .219 diameter and the holes in the crankcase were machined that size with not a lot of flange around them so I had to work with that dimension. What I settled on was to use .187 stainless tubing. This allowed me to turn a conical ferrule much like the brass ones that are used in compression fittings. I ground up a lathe tool with a .110 radius and used it to form the conical shape on a piece of stainless round stock. I then drilled a .166 holes through the ferrule followed by a .187 drill. With the part having such a thin wall I wasn't sure how it would turn out but when the drill broke through the back side of the part it just popped onto the drill shaft.

Next up was to make a set of dies to bend the .187 stainless tubing. The usual process was followed, cut to length, plug one end with a Teflon plug, melt Cerro alloy, fill the tube, bend the tube and then melt out the alloy. Being as the tubing was a little smaller I tried a die that gave me a little bit tighter bend.

I then had to make another set of mounting flanges. With this done I silver soldered the flanges and ferrules onto the tubes. With the conical ferrules soldered to the tubes it allows the pipes to be snugly inserted into the crankcase and swiveled to allow for any small misalignment of the flange to the head. Four of the tubes came out spot on with one needing a small amount of filing to get it square.

As I said, a lot of work that doesn't show much in the pictures.

 

[gbritnell]

Up next was the plumbing for the oiling system. I had designed the oil pump and had a rough idea of how it was going to move the oil into and from the engine but really didn't drill too many holes until the engine got to this stage. With the engine all bolted together it was easier to see how things might work so some more time was spent on the drawing board to make it work.
The first line was the pressure feed to the rods and the cam ring. The mains are sealed ball bearings. I came up with a banjo type fitting for the line ends and they are working fine. The return oil comes from a small sump at the bottom of the crankcase and passes to the pump through internal passages drilled into the crankcase. With the pressure line finished I chucked the engine into the lathe to give it a spin and squirt some oil into the feed side of the pump. As I dripped oil at the inlet port it was pulled into the pump and within a short time the oil was squirting out of the return side of the pump. Well the pump works.

 

[gbritnell]

The next part of the project was to make a mounting frame for the fuel and oil tanks. Awhile back I had posted request for some 1" square brass tubing. Although I got several answers the best I could do was 3 feet of the material when I really only needed 4 inches. I actually had wanted to make them from aluminum to keep all the parts looking the same but didn't have a good way of sealing the end caps. I ended up with some 1" square aluminum tubing with a .125 metal wall. I machined a .062 lip around the inside of both ends going down .094. I then cut a fitted some .062 end caps leaving a .031 reveal. In discussions with a couple of fellow modelers the idea of sealing was to use JB weld. I had reservations but experimented with some extra pieces and found that even when immersed in gasoline for an extended period the JB weld wasn't affected so with the end caps fitted to a nice push fit I coated the inner side of the recess and pressed the caps in place. Time will tell.

 

[gbritnell]

The last 2 pictures are just overall shots of the engine, framework and tanks.
gbritnell

 

[b.lindsey]

George, each new update is all the more amazing. To be at this point on such a complex project in the time you have done it is almost superhuman, but that said...thanks for the inspiration you provide and the superb craftsmanship you never fail to exhibit, not to mention the wonderful photography as well!!!

Bill

 

[ozzie46]

I didn't think it was possible but it keeps getting better and better as time goes on. :bow: :bow: :bow:


Ron

 

[ronkh]

Hi George,

I am also thinking of doing an engine similar to yours as a winter project.
The only problem I have is that I do not know when the next ice-age (winter) is going to occur in which to give me the time to do one!! (And I'd need that amount of time)!!

On a serious note, I have worked in machine shops for over 40 years (and am still doing so), and I have only occasionally seen such craftmanship on a par to yours that has made my jaw drop.
This work was by real craftsmen from my early day's and many years before CNC, computers etc and were made by bench-workers/machinists etc, who knew how to use their hands, eyes and brains.
You use all three to perfection!

Kind regards,

Ron.

 

[Lesmo]

George I am lost for words and can only look on in amazement at such craftsmanship. I think Ron sums it up perfectly

Les :bow: :bow: :bow: :bow:

 

[Deanofid]

George, thank you for the continuing pictures and text. I know you have put an immense amount of
work into this project, and to take time out for doing photos and writing so we can all see and learn
is quite a wonderful thing for us on the receiving end.

Dean

 

[ronkh]

Hi George,

Any further progress on this build?

Kind regards,

Ron.

 

[gbritnell]

Hi Ron,
Yes as a matter of fact I finished all the plumbing, lines fittings and valves, so the oil system is ready to go. I started on the spark plugs today. I got the bodies machined and am working on the insulators at the moment. Once the plugs are finished I just have to make the handle for the oil stop valve and the linkage for the carb and everything will be made, except the propeller. I've been online looking at how they are made. I would like to make a 3 bladed aluminum prop. I think they have some character to them. I just have to figure out how to cut the curves on the blades. I'll post some pics of the plumbing and plugs later on this evening.
gbritnell

 

[ronkh]

Thm:

 

[gbritnell]

Hi Ron,
Here's the update on the oil lines and spark plugs. It's getting close now.

 

[gbritnell]

And the spark plugs. These are 10-40 thread. With the smaller size I won't be able to use the normal vacuum fittings for the boots so as with the 302 plugs I'll just have an eyelet on the end of the plug wire and a knurled nut (0-80) to hold it in place.
gbritnell