Engineering on the cheap

engine

suggestions as

As a starting point why not take a look at how the available models work. My son has one, I think they are called air-hogs or something. There is a plastic container (an old drink bottle would be ideal for this) that you pump up with air, and this drives a small motor. The motor is actually very clever in it's simplicity. There is a small ball-bearing operated valve at the top of the cylinder, when the piston gets to the top and presses it a blast of air is released to push it back down.

I can't remember if it is the same on the plane, but on a car powered by the same kind of motor the piston was not connected to the con rod. It just had a dish shape in the bottom which pushed onto the rounded end of the con rod. This meant that once the air supply had run out the piston would stay at the top of the cylinder and the crank & con rod would run free, allowing it to free-wheel with no drag from the engine.

These are not too expensive, you could always buy one as a starting point -I bet loads of working engines & air tanks get thrown away because the plane has been crashed and the wings are broken.

Regards

Kev>

Thanks guys, I never thought of the turbine idea. I guess some form o

gearbox would be required to drive a prop, but if it drove a fan i might work without

-- Sergean

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This reminds me of something I was told when an apprentice. Never to spin a ball bearing on your finger with an airline to clean it. Apparently if a bit of grit or such like, causes it to lock up, the ball bearing will continue to spin across the workshop floor with your finger still attached!

Lionel