Friday, August 19, 2005

Bob Parks on adverse yaw and dihedral in gliders

Well, sort out priorities here.. adverse yaw in transient maneuvers is probably not that critical in the overall performance. One key to efficient glider flying is not wasting energy on unneeded maneuvers, regardless of what they are. ;-)

More critical than short transients is how efficiently the model can do near steady state turns in a thermal. The big driver is having enough dihedral to be able to track a thermal turn at high lift coefficients, with reasonably stability. In the past, ailerons always meant also having low dihedral (an offshoot, I think, of F3b models optimized for the speed and distance tasks). It took forever, but there are now some aileron airplanes with enough dihedral to thermal well.

A very good pilot with full 3 axis control is always going to be the best performance. As pilot skill goes down (or the pilot is wanting to allocate his attention to tactics rather than turning), then the answer will change. Actually, one of the very early seeds of the Bubble Dancer concept was when I was at a big soaring meet about 13 years ago (Visalia), and was watching a lot of pilots just wallowing around the sky with flat wing molded airplanes, and realizing that they would get MUCH better flights with an RES ship.

Some of it comes down to personal preference. I happen to like flying RES gliders. I find it relaxing, and it lets me dedicate a lot of my attention to "tactics".. i.e. what is happening in the air, where the birds are, what the feel of the air is etc. I don't compete any more, so I tend to fly alone, no caller etc. I fly other aileron airplanes (3D electrics, jets), so I probably want different things out of my gliders than many people would. I just happen to like the way a good rudder/ dihedral sailplane flies.

Anyway, the answer for competition is to fly the plane that will give YOU the best score. The hot shot pilot who won with his F3B airplane probably would have won it with any other plane too, but that doesn't mean that what he flew is what you should fly. Note that the airplane that gives you the best score might just be the one you ENJOY flying the most.


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