RE: Best .21 engine
Everytime I hear a PICCO .21 run in a car, there is always that little bit of "wonderment" about how it would do in a plane. They look like a sleeved down and destroked .35, [from a size and weight stand point], and the usefull HP / RPM range would probably only allow you to swing a 1/2A prop, so you would end up with a screaming power plant in a plane that just isn't gonna go anywhere. But I could be wrong, just haven't seen anyone pull it off. Those engines are mighty expensive too, might as well buy a NELSON.