Ideal 40 hp/3000 rpm Direct drive inverted Two-stroke single cylinder engine?

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sotaro

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So your plan is to use crankcase compression with overhead valves on a two stroke single. This is the heaviest, least reliable form of two stroke that I can think of. Crankcase compression is great for low cost low power engines. For highly intermittent use engines, engines that spend months on the ground not being used, then used at high power for hours on end, crankcase compression is a reliability issue. Then to add the weight of a valve train. How much better combustion efficiency can you get with the increase in weight, cost and complexity? Liquid cooled or air cooled?

Sorry to rain on your parade, but this doesn't compute in my echo chamber.
 

Niels

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So your plan is to use crankcase compression with overhead valves on a two stroke single. This is the heaviest, least reliable form of two stroke that I can think of. Crankcase compression is great for low cost low power engines. For highly intermittent use engines, engines that spend months on the ground not being used, then used at high power for hours on end, crankcase compression is a reliability issue. Then to add the weight of a valve train. How much better combustion efficiency can you get with the increase in weight, cost and complexity? Liquid cooled or air cooled?

Sorry to rain on your parade, but this doesn't compute in my echo chamber.
A Hirth 504 from WW2 has roller bearing and induction from crankcase.
It is an inverted fourcylinder fourstroke and some are still flying in Europe and next to none has been opened in crancase and still running like sewing machines.
Maxpressure and MEP is same as my wonder engine and weigth is 25 kg per litre(there are four) and wonder engine is around .0.8 litre so ca 20 kg for a 30kW 50 rps is goal.
 

sotaro

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Joined
Feb 26, 2011
Messages
289
Location
San Francisco
A Hirth 504 from WW2 has roller bearing and induction from crankcase.
It is an inverted fourcylinder fourstroke and some are still flying in Europe and next to none has been opened in crancase and still running like sewing machines.
Maxpressure and MEP is same as my wonder engine and weigth is 25 kg per litre(there are four) and wonder engine is around .0.8 litre so ca 20 kg for a 30kW 50 rps is goal.
I will go rain somewhere else now.
 

Niels

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Aug 15, 2019
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253
I don’t think you can eliminate reaction torque. If it were possible, helicopters would be tail-rotorless.
The constant part of reaction torque(mean torque,zero order) is taken care of by the ailerons when airborne and undercarriage when on ground.
Each of the sine shaped composants can be part or totally eliminated by pairs of shafts rotating one,two,three etc times as fast as crankshaft.
 
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Niels

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Aug 15, 2019
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That only works if ailerons have enough airflow or prop wash.
Ailerons when airborne or undercarriage on ground
I think the pilot will find the torque of a single objectionable. Four cylinder engines are most popular.
Torque reaction variation from six cylinder fourstrokes are small and feel like luxury and money enough.
Four-cylinder engines feel OK when firing regularly
Two cylinders like 1/2VW,V2-industrials indicate poor cheapskaters.
If I can make wonder single cylinder two stroke engine ignite and burn same way each cycle it will feele close to a four cylinder fourstroke and be roughly half the mass and length of engine. .
 
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