Hi Brenner, I was able to get my other Spark flying with the Neu motor and RASA 20.5x14 combo, 20 flights now and not completely trimmed out but just about there, and it's flying well and I hope to have both planes flying the remainder of the season. The planes are very similar in roll rates, elevator and rudder response and vertical speed but very different in other ways. On vertical up lines there is very little correction needed except for wind with the contra but the single prop setup I'm constantly making small adjustments to maintain the straight line, stall turns are very easy with the contra - essentially hit the rudder at the right time - while the single prop setup I need to work the ailerons to maintain the wings in the proper alignment, snaps are much easier to setup with the contra - the snap speed is essentially the same both directions while the single prop setup the speeds are very different, spin entries are much easier with the contra - maintain flight path with essentially rudder only and feed elevator until stalled but the single prop setup needed more inputs with ailerons and rudder to maintain the flight path. I'm not saying that the Spark with the single prop is not flying well, it's actually flying very nicely, it's just that the contra Spark is easier to fly.

Dave