Now we're comparing apples to avacadoes. Control line speed models do not use the long high aspect ratio wings because they need the improvement in L/D or reduction in induced drag. They went to the extreme shown in CP's pic purely because the wing shrouds and streamlines as much of the very draggy round wire control line as possbile. And control line combat has gone to as high an aspect ratio as the structures can comfortably manage due to the need to pull massive G loads for direction changes while losing as little speed as possible. In that respect they can be compared to a pylon racer but not to an open course pure speed design. Just different requirements leading to different answers.

Dick, if it was purely about straight line speed then some lower aspect ratio would likely be found to be best. I say "lower" instead of just "low" because daRock is right in that there's always more to the picture than we include in discussions on fundementals such as this.

But the interesting point is when it comes to our models is that we still need to be able to turn them so as to keep them in sight for control. As shown at extreme speeds even a big open "county size" turn can generate enough load that the wing is asked to work harder and some loss is found. So even for these pure speed models there's an optimum aspect ratio. It may well be that this can be stubbier than a purpose built pylon racer and make a gain.

I find it a little funny that over in the Extreme Prop Speed forum it's all about the delta models. Yet those designs are pretty much the worst possible planform for bleeding off speed in a turn. Even a big open turn. I guess a smaller and harder to see model with a honkin' big engine on it that looks faster than it really is generates enough adrenaline to stir the soul....