Are there upper and lower engines sizes for breathpower (2psi ?) to turn over an engine ?
ie as the model engines get bigger more mass and therefore more inertia to overcome ?
and as the engines get smaller relatively higher frictional forces to overcome both in the mechanical parts and in the airways ?
Reason I ask is my third engine is the smallest so far, 10mm piston diameter, 10mm stroke, very long piston therefore large cylinder contact area, 1.0mm inlet port. It is very easy to turn over by hand but is far smaller than previous engines and although it runs easily on tyre inflator air pressure at 1800rpm it doesn't turn over on my lungpower like the first two did. Huge piston contact surface area compared to first two and its just awkward to hold still whilst puffing air into it.
From the Stan Bray book and its the Tommy Toe plan.
Bill
ie as the model engines get bigger more mass and therefore more inertia to overcome ?
and as the engines get smaller relatively higher frictional forces to overcome both in the mechanical parts and in the airways ?
Reason I ask is my third engine is the smallest so far, 10mm piston diameter, 10mm stroke, very long piston therefore large cylinder contact area, 1.0mm inlet port. It is very easy to turn over by hand but is far smaller than previous engines and although it runs easily on tyre inflator air pressure at 1800rpm it doesn't turn over on my lungpower like the first two did. Huge piston contact surface area compared to first two and its just awkward to hold still whilst puffing air into it.
From the Stan Bray book and its the Tommy Toe plan.
Bill
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