Re: Rotax Sonex
Posted: Tue May 26, 2020 5:41 pmBy the way I have been running the engine on the ground to adjust the prop pitch and the engine runs strong and smooth. Fires up as soon as I push the start button.
gcm52 wrote:When I moved the engine, I moved the CG of the Rotax engine 7 inches forward of where the CG of the aerovee engine was. I tried to keep the thrust line the same. To allow a larger diameter prop, which is necessary with the Rotax, I lengthened the nose strut by three inches. I have a 64" diameter Warp Drive prop on it now. I am toying with the idea of putting on a four blade Warp Drive just for fun. I also am probably going to remove the 1" prop extension on there now as I actually don't need it for cowl clearance. Attached are a couple more FWF photos so you can see what I did. I used a Rotax ring mount and designed a custom mount going from the ring mount to the firewall.
George
Thanks for the additional info George. 7 inches of movement for the CG is definitely out there. My best estimate shows about 3.5" of CG move, which makes the prop about 6.5" forward of the normal location. since it's easier to fix nose heavy, than tail heavy, I'll probably shoot for 4" of CG movement. For the tailwheel version, with standard gear, I'll likely end up with a 4 blade Bolly (sold by Hoverhawk). I won't make a decision until the engine is mounted and the prop clearance is known.
Thanks,
Rusty
PS- Sorry to Jake for all the Onex chat on his Sonex thread.
