# 2-stroke radial engine



## kcnegemen (Nov 15, 2012)

hello.

I designed 2-stroke radial engine.

Radial Engine work?


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## Teza (Nov 15, 2012)

G'day mate,
Looks good but how will it scavenge the crankcase to provide fuel mixture for the cylinders 
Cheers
Terry


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## kcnegemen (Nov 15, 2012)

roughly the carburetor








Engin


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## ccstudent (Nov 15, 2012)

this i have got to see!! will it have glow plugs??


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## mu38&Bg# (Nov 15, 2012)

There will be no pumping action in the crankcase. A pump of some sort is used in multi-cylinder two strokes with a shared crankcase. This should help explain the concept. http://www.rcmplans.com/issues/requested/content/reviews/pdf/r-rv-berger-121997-1-1.pdf


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## Entropy455 (Nov 15, 2012)

Yup.

You&#8217;ll need forced induction.

Similar to the 2-stroke Detroit diesels, which use superchargers.

It could be an easy way to build a radial &#8211; in that you wouldn&#8217;t have to construct a complex cam-gear, rocker arms, valves, etc.


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## Omnimill (Nov 18, 2012)

dieselpilot said:


> There will be no pumping action in the crankcase. A pump of some sort is used in multi-cylinder two strokes with a shared crankcase. This should help explain the concept. http://www.rcmplans.com/issues/requested/content/reviews/pdf/r-rv-berger-121997-1-1.pdf



Thanks for posting the link. That's a neat engine!


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## kcnegemen (Nov 20, 2012)

Hello

CARBURETOR

Waiting for your comments ....







Engin

Türkiye.....


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## mu38&Bg# (Nov 20, 2012)

This requires a positive displacement pump. Vane type is common in model engines. Rootes or screw compressor in full scale.


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## kcnegemen (Dec 18, 2012)

production start

Engin
Türkiye (ankara)


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## canadianhorsepower (Dec 18, 2012)

What ar3 your tming specs for intake transfer and exaust???
interesting idea


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## mu38&Bg# (Dec 18, 2012)

The radial flow compressor you have will not work at crankshaft speeds. You must use a positive displacement pump for this to be successful at model scale. A radila flow compressor could work, but there would be a lot of issues to work out in the design of the compressor itself and it would have to turn at very high speed. A vane pump displacing ~1.5 times cylinder swept volume will work perfectly.


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## kcnegemen (Dec 19, 2012)

hello
  diesel pilot
Can you give an example of a positive displacement pump

Can you give an example of a radila flow compressor ...

sufficient to run 2 times speed compressor will ya?

What's your suggestion to me.

then waiting for the answer.


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## aonemarine (Dec 19, 2012)

looks interesting, not sure a impeller is the way to go for forced induction in this application as it needs some serious rpms before it starts building some pressure. also not sure of the plumbing arangement, unless thier is something im missing.......


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## MuellerNick (Dec 19, 2012)

I would not say that a blower doesn't work at all. They do and did on 2-stroke Diesels. But I doubt that they work at crank-RPM unless they have a relatively huge diameter.
It would need some calculating (blowers can be calculated) before making the first chips.


Nick


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## dman (Dec 19, 2012)

the problem here is that a centrifugal compressors pressure ratio is roughly proportional to the tip velocity regardless of restriction so flow is not steady it is mostly determined by pressure (rpm) and resriction. the pressure will change slightly with flow but if you look at pressure maps of turbo chargers the rpm lines are almost horizontal, both pressure and flow increase exponentially with rpm. i don't know all the math but a ~ .5 to 1"  compressor wheel wont make much pressure even at full throttle and it's not too practical to achieve the required rpm with mechanical means. the engine may run at very high speeds but it wont idle. 

you need a positive displacement pump like a vane, roots, screw, or possibly wenkel if you really want a challenge. positive displacement means that a revolution moves a determined amount of air. the flow increases linearly with rpm. this is needed to precisely evacuate the exhaust effectively without blowing fuel through the exhaust

http://image.moparmusclemagazine.co...opar_superchargers+types_of_superchargers.jpg


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## mu38&Bg# (Dec 19, 2012)

kcnegemen said:


> hello
> diesel pilot
> Can you give an example of a positive displacement pump
> 
> ...



Vane type was shown in the link I provided before. http://en.wikipedia.org/wiki/Rotary_vane_pump other positive displacement types work, but are a bit more complicated to manufacture. A single cylinder engine using the crankcase for primary compression is a type of positive displacement pump.

Even twice crank speed would not be enough for a radial flwo compressesor( what you've drawn in simplest form). I have a 31mm Borg Warner turbocharger compressor wheel for a turbine engine project. To achieve 1.5 pressure ratio it must spin 185,000 RPM. Yes, that's right, one hundred eighty five thousand RPM. This is off the compressor map supplied by the manufacturer. Matching flow to the engine speed is an issue as well. Even a much large compressor say 100mm, properly designed I might add, would need ~50,000 RPM.


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## lohring (Dec 19, 2012)

Don't forget piston pumps.  In small sizes they are surprisingly efficient and can easily be incorporated into the pistons of the engine.  With some clever piping, the pump delivery can be timed to match the intake porting in a multi-cylinder engine.  

Lohring Miller


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## mu38&Bg# (Dec 19, 2012)

Yes, that is certainly an interesting design. http://users.breathe.com/prhooper/opads.htm


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## kcnegemen (Dec 20, 2012)

hello

period of 4 times the belt off. There is a picture.

waiting for your comments ...


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## kcnegemen (Dec 20, 2012)

http://www.rcmplans.com/issues/requested/content/reviews/pdf/r-rv-berger-121997-1-1.pdf


this site made &#8203;&#8203;with atmospheric pressure compressor.

interesting.


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## aonemarine (Dec 20, 2012)

Better up that belt drive by 20......then its a maybe....


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## MuellerNick (Dec 20, 2012)

There are some valid objections. But some numbers should help getting the blower right.
2-strokes have a CR of the crankcase of 1.3 &#8230; 1.5. But you do have that pressure only at the BDC. Obviously, it drops to 1 at the end of scavenging. So there is an average pressure of 1.15 &#8230; 1.25. If you consider the efficiency of sucking in the air that might be at 90%, the pressure drops even more.

Assuming a pressure of 1.2, you would need a blower that:
* makes a pressure increase of 1.2
* delivers a volume of 3 * displacement (number of cylinders * displacement) at 1.2 pressure

If you can't find how to design blowers, you should at least build a model and verify that it makes enough pressure and volume. The equipment to measure that is really easy to make by your own. Some tube and water. Makes a pressure indicator and a Prandtl tube (to measure speed).
Build that blower, at the outlet add some tube with a throttle at its end. Adjust the throttle to get 1.2 pressure, measure the speed of air going out. With the speed and the cross-section (and an adjusting factor) you get the volume.

Nick


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## dman (Dec 20, 2012)

kcnegemen said:


> http://www.rcmplans.com/issues/requested/content/reviews/pdf/r-rv-berger-121997-1-1.pdf
> 
> 
> this site made &#8203;&#8203;with atmospheric pressure compressor.
> ...



it's not that you need a compressor. it's that you need an air displacer. the air density has little to do with it so the pressure ratio calcs are not an exact science in this application. the timing on most 2 strokes leaves the exhaust open after the intake so the the nominal pressure in th cylinder is never more than exhaust back-pressure until after the exhaust (and therefore the intake) is closed. but since the exhaust is full of pressure waves bouncing around the exhaust evacuation and cylinder pressure is all over the place in a running engine. with a positive displacement type pump you will mechanically overcome any intermittent back-pressure but with a centrifugal pump you will not.


also you list no dimensions. centrifugal compressors don't scale like a pump. they give pressure per rpm*diameter while a positive displacement type gives a volumetric flow rate per rpm. coming up with adequately pressure to reliably scavenge the exhaust is one thing but achieving it is another. if the engine dimensions dictate a 1" compressor wheel you will need rpms in the hundreds of thousands just to create 3psi and you will not be able to do that through a belt drive. the mechanical forces wont allow it. it would be too difficult to change the compressor speed putting huge strain on the belts and the compressor would act like a flywheel, due to the great rpm it would appear too heavy to the engine to drive it and the belt system would rip its self to pieces. the only way to drive something to these speeds is with a turbine which is a whole other can of worms. like the logistics of getting the compressor up to speed for start up.  there is another design that could in theory drive something high speeds which is a type of planetary arrangement that uses wheels instead of gears and is driven by an outer ring that is slightly flexible so it's a sort of rigid belt in a way. this design is limited to about a 1:14 ratio geometrically so 10,000 rpm engine could drive a 140,000 rpm compressor in theory but i don't know how reliably it could do it. and you are still faced with the dilemma of what happens when the engine idles. 


the engine in that article has a vane type pump which is positive displacement and has already been recommended to you several times. the vanes slide in the central hub which is concentric to the crank but the housing is offset. with this arrangement the vanes create chambers in the housing that change is size during rotation drawing air in through a channel in the section where the chambers expand that expands and squeezing it out through another on the opposite section.


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## kcnegemen (Dec 20, 2012)

dman said:


> it's not that you need a compressor. it's that you need an air displacer. the air density has little to do with it so the pressure ratio calcs are not an exact science in this application. the timing on most 2 strokes leaves the exhaust open after the intake so the the nominal pressure in th cylinder is never more than exhaust back-pressure until after the exhaust (and therefore the intake) is closed. but since the exhaust is full of pressure waves bouncing around the exhaust evacuation and cylinder pressure is all over the place in a running engine. with a positive displacement type pump you will mechanically overcome any intermittent back-pressure but with a centrifugal pump you will not.
> 
> 
> also you list no dimensions. centrifugal compressors don't scale like a pump. they give pressure per rpm*diameter while a positive displacement type gives a volumetric flow rate per rpm. coming up with adequately pressure to reliably scavenge the exhaust is one thing but achieving it is another. if the engine dimensions dictate a 1" compressor wheel you will need rpms in the hundreds of thousands just to create 3psi and you will not be able to do that through a belt drive. the mechanical forces wont allow it. it would be too difficult to change the compressor speed putting huge strain on the belts and the compressor would act like a flywheel, due to the great rpm it would appear too heavy to the engine to drive it and the belt system would rip its self to pieces. the only way to drive something to these speeds is with a turbine which is a whole other can of worms. like the logistics of getting the compressor up to speed for start up.  there is another design that could in theory drive something high speeds which is a type of planetary arrangement that uses wheels instead of gears and is driven by an outer ring that is slightly flexible so it's a sort of rigid belt in a way. this design is limited to about a 1:14 ratio geometrically so 10,000 rpm engine could drive a 140,000 rpm compressor in theory but i don't know how reliably it could do it. and you are still faced with the dilemma of what happens when the engine idles.
> ...


 

Dman
Using 55 mm compressor wheel.

I also have a problem in my head to fill.

140 000 cycles can not.

40 000 rpm max.

max engine speed is about 10 000.

7.5cc x 5 = 37.5 cc Cylinders

positive displacement vane pump and the corresponding image of the project, for example, the drawing you show an example.

Which do you think would be successful if I choose.


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## dman (Dec 20, 2012)

kcnegemen said:


> Dman
> Using 55 mm compressor wheel.
> 
> I also have a problem in my head to fill.
> ...



that's my point. it's just not gonna work at this scale



> positive displacement vane pump and the corresponding image of the project, for example, the drawing you show an example.
> 
> Which do you think would be successful if I choose.



there seems to be somewhat of a language barrier. but some air tools use a vane style motor. same thing but in reverse...

[ame]http://www.youtube.com/watch?v=qJ1QccN7LXg[/ame]

this should help. maybe another member has a blueprint.


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## kcnegemen (Dec 20, 2012)

perry carbüratör....


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## dman (Dec 20, 2012)

kcnegemen said:


> perry carbüratör....



sounds good. once you get the air pump sorted out. the renderings look great by the way. just want to make sure you have some workable engineering before you start.


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## canadianhorsepower (Dec 20, 2012)

maybe this would help

http://en.wikipedia.org/wiki/Rotary_vane_pump


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## kcnegemen (Dec 21, 2012)

have a bit of a language problem

Thank you dieselpilot dman power aonemarina canadionhorse

continue to design


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## kcnegemen (Dec 21, 2012)




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## kcnegemen (Dec 21, 2012)

Has there been carburator? dman.


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## canadianhorsepower (Dec 21, 2012)

very nice drawing


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## dave-in-england (Dec 21, 2012)

.
Wot ?  No piston rings ??  
and those connecting rods look a little .... Butch !!

This project will involve a hell of a lot of machining, and time.

I can see that the fan will just swirl the inlet mixture around endlessly inside the fan housing, without any pumping action to force any mixture into the cylinders.

What about having a re-design and making the engine a four cylinder model,
where two smaller diameter opposing pistons are actually used as suck-squeeze compressor cylinders to positively force the mixture into the other two working cylinders.

:hDe: 

.


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## Art K (Dec 21, 2012)

I normally wouldn't be very interested in a two stroke but I find the concept of a two stroke radial and the discussion on pressurizing the intake charge fascinating. I will be following this build.

Art


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## dman (Dec 21, 2012)

kcnegemen said:


> Has there been carburator? dman.



everything looks good to me now. this will be a great project.


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## dman (Dec 21, 2012)

dave-in-england said:


> .
> Wot ?  No piston rings ??
> and those connecting rods look a little .... Butch !!
> 
> ...



there is no fan. it's a pump that has been used successfully in the type of engine before. read the whole thread. the air blower vs air pump has been addressed the latest renderings have a proper pump. 

who needs piston rings? model aviation engines have none and they make pretty high power levels for the displacement..


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## dave-in-england (Dec 21, 2012)

My comments about the fan were directed at the cad model on page 1, which shows a fan being used to blow the mixture into the inlet ports.
However, the comments I made seems to have been placed under the model of the vane pump on page 4.


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## Till (Dec 22, 2012)

It will prove to be very useful to create a small handwritten essay  specially on the cylinder ports... Please build a running single  cylinder engine first before you start with the radial to avoid the big  disappointment.

I strongly recommend using a third party (chainsaw?) carburetor instead  of your own design, because from what I've seen so far in this thread,  you still need to learn quite a bit and carburetors are a mayor source of  avoidable errors. As soon as the engine actually runs, you can still  design your own caburetor.

The blower vanes should be slightly  spring loaded and of  material with good surface slip, such as teflon.  Lots of oil in the fuel mixture will establish proper sealing.
I  recommend building a prototype with the blowers case supported by an  adjustable excenter, so you can determine the proper pressure for your  engine. 

If you can't exclude flexing of the crankshaft under load conditions,  you better use rather thin, flatsided connecting rods with the  flexibility to compensate for the angular missalignment of crankpin and  gudgeon piston pin. This will partly compensate for bad manufacturing clearences and unexpected vibration issues, too.

Ringless pistons without special coatings and conical cylinder bores require material combinations of equal thermal expansion, so you'll likely go for grey cast iron.

The  cylinder head is exposed to maximum thermal stress and therefor needs  larger fins, specially if you have no experience with lean mixture  conditions.


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## kcnegemen (Dec 31, 2012)




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## kcnegemen (Dec 31, 2012)

started production.


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## kcnegemen (Feb 4, 2013)

Hi

I was sick for a long time.

I'm moving slowly.


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## kcnegemen (Feb 21, 2013)

temporary installation


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## Till (Feb 21, 2013)

Cooling fins on the cylinder head are needed to prevent overheating.
google translator: silindir kafas&#305; üzerindeki so&#287;utma kanatlar&#305;n&#305; a&#351;&#305;r&#305; &#305;s&#305;nmay&#305; önlemek için gerekli


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## kcnegemen (Feb 21, 2013)

I'm going in the depth of 3mm yes wings.

till thank you.


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## kcnegemen (Feb 21, 2013)

https://thkmodelucak.com/store/product/1309-no4-buji-orta-sicak-173704


Is there anyone know what plugs teeth ...

drill diameter is about 5mm

help ...


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## dman (Feb 21, 2013)

kcnegemen said:


> https://thkmodelucak.com/store/product/1309-no4-buji-orta-sicak-173704
> 
> 
> Is there anyone know what plugs teeth ...
> ...



not sure but they are likely metric. mic the major dia, then check threads with thread gages.


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## kcnegemen (Feb 21, 2013)

If anyone knows what that thread waiting for help


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## vcutajar (Feb 21, 2013)

I suggest you send them an email and ask for the thread size.

Vince


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## kcnegemen (Feb 21, 2013)

Mail


[email protected]


thank you


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## Till (Feb 21, 2013)

The link is for a glow plug, they usually have UNEF 1/4-32 threads...


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## wildun (Feb 21, 2013)

I have just found this thread and have briefly read through it -  interesting project of course and it does seem to be going ahead, but still with many unresolved problems, eg. what type of cylinder/piston combination, layout for the scavenging pump (ie. delivery of fuel mixture to the cylinders), cylinder/head cooling, and the biggest one of all - how is it going to be lubricated?? - forced lubrication with a pump? or with the more common two stroke mix?

Starting with the two stroke mix - if the charge is delivered from the scavenge pump straight to the cylinder, then what wil lubricate the crankshaft bearings? - surely it is possible to deliver the charge from the scavenge pump straight into the crankcase as in a common two stroke thereby pressurising the crankcase and passing the charge into the cylinders through transfer passages as in any normal single cylinder two stroke. 
 Also (for pre mix) it would be a good idea to use roller bearings of some sort for the crankshaft as, if plain bearings are to be used, the oil/fuel mix will probably need to be around 16:1. whereas 50:1 would be common in chainsaw type engines with needle roller cranks. 


As* Till* mentioned, slightly tapered pistons and the correct materials need to be used in the piston/bore combination and most of the smaller model aircraft engines use ABC,  ie. aluminium pistons, brass liners -( chrome plated bores) 
Don't quote me, but I do believe that ringless pistons require a high oil concentration around them. Ringed pistons are no harder to make than ringless pistons, possibly much easier and do not reqire all that oil! as opposed to the ringless type and having to fit them in the correct position in the tapered bores! 

I see *Dave in England *also made a good suggestion when he said that half of the pistons could be used as compressors. 
When he said that an even number of cylinders should be used, I'm guessing that he meant that the charge would be fed straight into the cylinders, (thus necessitating an oil pump). However if the oil/fuel mix is being delivered into the crankcase, then the number of cylinders could probably remain the same - say two compressor pistons and three power pistons and the amount of charge being delivered could possibly be compensated/adjusted with a larger or smaller cylinder volume in the pumping pistons (while trying to keep piston weights correct of course.

I still don't understand why the machining etc. has been started without the design being finalised - or the preoccupation with minor things like plug threads when perhaps the most important thing like lubrication still has not even been mentioned till now, never mind sorted! ...............oh yes,  and then there's ignition type and ignition timing! 
Of course Timing won't be an issue with a glowplug, but Compression Ratio may be and I think that glow ignition will probably restrict you to alcohol fuel.

Sorry if I missed some things or have misunderstood them but I will re-read the thread and I hope that I have got it right, please correct me if I'm wrong (when I go through it all again,I may find that I am!)  

There is a long way still to go, but its good to see you making the effort (unlike me) and I think it'll eventually work out!


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## kcnegemen (Feb 22, 2013)

T&#304;LL 1/4-32 I found my .... 10 $ ....turkey


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## kcnegemen (Feb 22, 2013)

till

For me, this 35 cc radial engine, the oil pump can I Suggestions

ebay, hobyyk&#305;ng. can I sites, etc. from

I want to make glow engine lubrication ...


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## kcnegemen (Mar 27, 2013)




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## kcnegemen (Mar 27, 2013)

the last case


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## Till (Mar 29, 2013)

Your rotary vane blower will not work properly, the axis must be off center with the case.
Look this picture, you can see clearly how it should work: http://www.en-found.com/rv blower.htm 
Google translator:
Sizin döner kanatl&#305; fan düzgün çal&#305;&#351;maz, eksen dava ile merkezi kapal&#305; olmal&#305;d&#305;r.
Bu resim bak, bunu nas&#305;l çal&#305;&#351;mas&#305; gerekti&#287;ini aç&#305;kça görebilirsiniz:
http://www.en-found.com/rv blower.htm

btw I learned that "döner" (in Germany this is turkish style meat on a grill-spit) means "rotary"


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## mu38&Bg# (Jun 11, 2013)

How is this project going?


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## larz001 (Nov 28, 2013)

it looks like he copied lee berger's design

https://www.rcmplans.com/issues/requested/content/reviews/pdf/r-rv-berger-121997-1-1.pdf


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## wildun (Nov 29, 2013)

To be honest, although it is basically similar, I don't really believe that it was copy of anything, it was more of a design exercise which was only an idea and still in it's infancy.
I do feel that it was started prematurely without a lot of understanding of all the principles involved, maybe because he had access to a good draughting program, (drafting to you Americans), also machining expertise and facilities.
I had hoped he would bring it to a successful conclusion, but it looks like it has been dropped or hopefully just shelved for the moment!
The lack of communication because of the language barrier certainly didn't help either, but I still feel that I must congratulate this guy for his efforts and I do hope he overcomes everything and is able to persevere enough to see it through.


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## WOB (Nov 30, 2013)

MuellerNick said:


> I would not say that a blower doesn't work at all. They do and did on 2-stroke Diesels. But I doubt that they work at crank-RPM unless they have a relatively huge diameter.
> It would need some calculating (blowers can be calculated) before making the first chips.
> 
> 
> Nick


 
The blowers on Detroit Diesels are positive displacement ( Roots type)
Large stationary 2-stroke Diesels(back up generators) start on their Roots blowers and run on turbo-chargers for better fuel economy.

WOB


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## Shopgeezer (Feb 4, 2019)

larz001 said:


> it looks like he copied lee berger's design
> 
> https://www.rcmplans.com/issues/requested/content/reviews/pdf/r-rv-berger-121997-1-1.pdf



This is an old thread but if anybody out there is listening, are the Lee Berger plans still available somewhere?  RCM plans are long dead and the few places still providing them like RC Groups only seem to have airplane plans, no engines. I am fascinated by the 2-stroke radial engines Ralph Barnette and Lee Berger built. I have plans for a 9 cylinder engine using Cox cylinders and pistons but would love to find the Lee Berger plans using the K&B .65 cylinders.


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