[Tom] likes to build little helicopters and decided to build one that runs on compressed air. (Video, embedded below.) Turns out it was a little harder than he thought. Originally, he was trying for a compressed air quadcopter. He’d already worked with an air turbine, but putting on a vehicle that can lift itself into the air turns out to have a lot of hidden gotchas.
[Tom] went through a lot of design considerations to arrive at the helicopter design. He considered counter-rotating props, but there were a host of problems involved. He finally settled on a single prob with a tail rotor that resides on the far end of a long boom to allow the resulting lever arm to reduce the work required of the tail rotor.
Some of the best parts of this build are the test setups. We liked the test rig he has for testing the thrust of a propeller. It allowed him to understand that his quadcopter design wasn’t feasible with the props he had on hand. His schlieren photography setup was interesting, too, and provided some cool photos of the airflow.
In the end, the results were somewhat disappointing. However, you sometimes learn more from your failures than your successes. Also, an astute Hackaday reader might have some advice on how to make the flying machine better. We feel like it is very close.
We’ve seen [Tom] working on this in one form or another for a while. Some of his air-powered designs are quite sophisticated.