[Tom Stanton] has been experimenting with compressed air motors on model aircraft for several years. However, keeping them airborne for longer than a few seconds has been a challenge. But now, he has achieved a breakthrough with his latest design, achieving an impressive flight time of 1 minute and 26 seconds using only 4 liters of compressed air.
The new design of the engine features an expanding seal on the piston, inspired by the old Air Hogs toy plane. The wings of the model aircraft are constructed using lightweight 3D printed ABS ribs on a carbon spar, wrapped in heat shrink film. To maintain the wing’s shape, a thin balsa former is incorporated along the leading edge. The fuselage is made of a carbon fiber tube and includes printed fittings for the wings, V-tail, RC electronics, and soda/air bottles. A hollow nylon bolt holds the two bottles together end-to-end while allowing the motor to be screwed onto the front bottle. To reduce weight, the two V-tail control surfaces are actuated by single cables linked to servos, with piano wire torsion springs in the hinges maintaining tension.
During the testing process, [Tom] faced some challenges. One crash nearly caused severe damage to the airframe, but a 3D printed bracket at the center absorbed most of the impact, preventing total destruction. He also had to find a solution to protect his expensive carbon fiber propeller from damage during multiple landings, leading him to create a replaceable consumable connector.
If you’re interested in learning more about this project, there is a second video available that offers behind-the-scenes insights and technical details. You can also check out [Tom]’s previous attempts with diaphragm engines and his efforts to make them fly.
Image Credit : Tom Stanton @ Youtube