On Wednesday, November 6, 2013 8:39:53 PM UTC-6, John Carlyle wrote:
Thanks again, Steve, I appreciate your ideas. A few comments: 1) The people experiencing this problem at my club are flying a LS-8, a V2x, an ASW-27 and a Duo, all behind a Pawnee with tow ropes no shorter than 200 feet. Our G-103’s don’t seem to have the problem (longer wings? But then why the problem with the Duo?) 2) Our tow pilots are aware of the problem, and they’re working with us. We’re going to explicitly remind them of the potential for the problem each time they start towing us. 3) Next time I fly I’ll ask the Pawnee pilot (at altitude) to slow down and I’ll go into low tow to see if it helps. Since I fly an LS-8 which is reported particularly susceptible to the problem, if that works out for me it should help others (particularly at a site where the tow plane doesn’t have a radio). It won’t be rigorous, but a positive report might be of some use. -John,

Just guessing here, but are most of these reported control problems starting right after takeoff, or at some point during the tow, when the towplane slows down a bit for one reason or another? I have seen lots of problems when the towplane takes off and is starting to climb before the glider can get off the ground. And when the glider does get off the ground, he starts off in the towplane's wake. Been there. Not a happy place to be.

For the LS-8, V2, 27, and Duo, if the issue is starting for right at liftoff, this could be the case. The Grob, with its lower wing loading, has more margin above stall, so maybe it doesn't get as bad. Just a turbulent ride.. With a lighter wing loading towplane that really doesn't like to be on the ground above 60 MPH, it is vital that the towpilot not start his climb with a higher wing loaded glider until he is sure the glider is airborne. This does not mean he should try to stay on the ground, just don't start climbing until you have more speed.

If it is happening once you are above, say, 500 feet, climbing normally and all was well before hand, it could be that the towplane slowed down, you got lower to keep him in sight, and dropped down into the wake. Back to that lower incidence thing and not being able to see the towplane at lower speeds, and maybe the longer rope or low tow position would help in resolving the handling issue.

As for 3, John, if you do that, be sure to still be climbing, as the pictures and sensations change for level flight versus climb. Good refresher work before the next Flight Review!

Steve