RE: relationship of ground effect and wing chord
I'm certainly not having a debate here. Just sharing experiences and observations.
For example, there is testimony of a Q500 model floating on ground effect at 6' altitude for over a quarter mile. Here is an observation and opinion of that: The texts say it's effects are significant a heck of a lot closer to the ground than 6' for a model like the Q500s. So that sucker ain't even close to being in effective ground effect at roughly 1.5X it's wingspan above the ground. Since it's a racing plane with a highpitch, small diameter prop and a hot engine, my opinion of the cause differs greatly. That Q500 pilot had the idle too high. If ground effect could hold off a model plane about twice it's wingspan above the runway, it'd be so effective once the sucker actually got within half a wingspan, the sucker couldn't get through that cusion. And our models would never touch down. We'd have to walk out and pick 'em out of the air.
In my experience, every modeler who ever asked me to help them solve the "floater" problem got help that included adjusting their idle or their prop selection. Lots of them had lousy lowspeed needle settings. Probably three quarters of them had high idles for whatever reason. The rest were running high pitch props. Once we got the engine/prop at idle to quit pulling the airplane along at flying speed the ground effect no longer held the airplane off.
You know, there is more than one basic truism in full scale piloting. There is also the rule about controlling your altitude with the throttle. There is no mention about that rule no longer applying in ground effect.