Topspeed on a Sig Wonder
My Wonder is powered by an OS .15. I've tried various 8x4's and 7x6's on it. I like the ability to hand launch with the 8x4 (it virtually flies out of my hand). The 7x6 is a little faster but I have to give it a good chuck to launch.
If you're out for pure speed, go with a small diameter high pitch prop but honestly, the airfoil is so thick that if you really crave speed, you better find a different plane. Don't get me wrong, my Wonder if fun to fly and it is relatively fast but I've seen old ultra sports that would leave my plane choking on dust.
How much does your's weigh with the Norvel?
good luck,
Kevin