2-stroke radial engine
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Is there anyone know what plugs teeth ...
drill diameter is about 5mm
help ...
Is there anyone know what plugs teeth ...
drill diameter is about 5mm
help ...
not sure but they are likely metric. mic the major dia, then check threads with thread gages.
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!
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!
Last edited:
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 kanatlı fan düzgün çalışmaz, eksen dava ile merkezi kapalı olmalıdır.
Bu resim bak, bunu nasıl çalışması gerektiğini açıkça 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"
Look this picture, you can see clearly how it should work: http://www.en-found.com/rv blower.htm
Google translator:
Sizin döner kanatlı fan düzgün çalışmaz, eksen dava ile merkezi kapalı olmalıdır.
Bu resim bak, bunu nasıl çalışması gerektiğini açıkça 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"
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
https://www.rcmplans.com/issues/requested/content/reviews/pdf/r-rv-berger-121997-1-1.pdf
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.
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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