RE: Seagull Ultimate biplane 90 size
I have a Saito 125 on mine and it flies very well although I don't do 3d.Vertical climb is unlimited and for the type of flying that I do it is more than enough I usually fly at 2/3 throtle. If you plan to fly scale the 100 Saito would do.If you want a rocket i would use a 150 or 180 Saito or go to a 26 to 35 cc gas. I personally dont think the airframe would handle much over a 150. Hope that helps.....