Aviation consists of two major groups. Airplane enthusiasts, and helicopter enthusiasts. The two groups rarely get along, each extolling the virtues of their chosen craft. Somewhere in between are autogyro folks. People who like vehicles that blend the best (or worst) of both airplanes and helicopters. Aviation master [Peter Sripol] has dipped his toes into the autogyro world, but not without some trouble.
Autogyros are propelled by a propeller, like a plane. They also have a tail section that works similar to a fixed-wing aircraft. That’s where the similarities end though. Lift for autogyros comes in the form of a rotating set of blades, much like a helicopter. Autogyro rotors aren’t powered during flight. They utilize autorotation. The blades freewheel, spun by the air as the craft moves forward.
[Peter] recently got his hands on a full-scale autogyro. So it made sense to build a model to help learn to fly. This isn’t [Peter’s] first attempt with autogyro models. He’s built a few in the past, with limited success. This time he started from scratch and ran into even more problems!
[Peter] found that most autogyro models use gyroscopes to aid the pilot. These devices won’t be available on his full-scale ultralight, so [Peter] wanted to build a craft that flew without electronic assistance. His first designs resulted in crashes just after liftoff. [Peter] scaled the design up, because bigger models are always more stable in the air. He also found that aerodynamics don’t scale exactly to models, so some design changes were needed. Extending the tail finally gave him a stable craft, but it still had problems. Changes to the rotor head and blade design turned out to be the real keys to getting the model to work. The details are all available in this 49 page (and counting!) R/C Groups forum thread.
The nice thing about this model is that it’s not hard to build. Most of the frame is built from towel bars and aluminum bits you can pick up at the local hardware store. The blades are 3D printed with aluminum spars. [Peter] has promised to upload the design files by the end of May.