If you decide to go the ultralight path, there is a relatively new engine starting to be used on Gyros that I believe would be a major advantage to anyone trying to make ultralight weight. It is a single rotor, 4 stroke rotary engine that was originally designed for the Go Cart racing industry. It is called the Aixro XR50. It puts out a max of 48 HP and only weighs 35 lbs. This would give you 4 stroke reliability, more power than the Rotax 447, and a significant weight savings so you could add more in another area. You should check this engine out if you are set on keeping a Gyro under 235 lbs. "www.woelfle-engineering.com"