Last year I found an old air command low boy gyroplane kit that I am converting to a center line thrust machine. It will have a 3 Cylinder Yamaha engine, a Tangogyro tail, 3 blade Bolly Prop and Tangogyro Rotor head and blades. I will raise the mast a bit higher too. Lone Star Rotorcraft Club always has something in works too. For example, the modified the Green Aviomania AKA Kermit last year from a Yamaha powered machine to a Rotax 912 machine. Plans are in the works for it to change hands inside the club and have a new look and engine. Currently, the fuel tanks are leaking due to ethanol. There are other builds happening in the club too, including a Parson's trainer with a GA engine, Lycoming or Continental?
Recently, I decided to change the gear box on my Tangogyro from a 3:1 ratio to a 3.47:1 ratio. The Yamaha Nytro engine runs at 8200 rpm for peak torque and horsepower. My goal was to turn the prop slower with more pitch to make it quieter and more efficient at cruise without losing climb performance. My friend and CFI Ben Cadenbach has been flying very successfully with this combination in his Tangogyro.
My early flight tests went well, but, I started having some issues that I thought were related to the clutch that had almost 200 hours on it. I removed the new gear box to check the clutch and I found that the main bearing inside the adapter plate was bad, so I replace it and the clutch pads. The repairs did not resolve the issue. I was told to open the new gear box and check it. I discovered that the nut on the main gear which drives the prop had not been torqued properly at the factory and was slipping on the shaft. I torqued the nut to over 100 foot pounds as directed by the manufacturer. I did not fix the problem, I believe that the inside of the gear was damaged on the shaft and has to be replaced. I am sending it back to the manufacturer for the repair. In the mean time I am using the original 3:1 gear box.
