Thanks again for your thoughts, Steve. Sorry for my delay in responding.

All of our slow tow incidents have occurred above 500 feet; none of us has ever had a problem near the ground. Our airport elevation is 700 feet with unobstructed horizons, and the temperatures on the days of the incidents were mostly in the 70s. The Pawnee pilots claimed that they had been maintaining 80 mph during the climb to that point; but when they went to 90 mph the handling problem for the remainder of the tow was gone.

When the handing problem first happened to me I did think that I’d somehow gotten low and hit the wake. It didn’t make sense, because the proper sight picture in my LS-8 on tow has the tow plane touching the top of the glare shield, so it’s super easy to see if you’re too low (or too high). I climbed 20-30 feet, but when it didn’t help I asked for more speed and all was well. I haven’t asked the other pilots if they thought they’d hit the tow plane wake, but I will.

It may be a while before I can see if going into low tow will relieve our slow tow handling problems. I can’t fly for another week and the weather is getting more problematic. But when I do the experiment, I’ll make sure that I’m climbing, as you advise.

I must say I’m very pleased to now have an aerodynamic understanding of why gliders on tow can have handling problems. Several more experienced pilots had told me that I’d be fine as long as the tow plane kept on flying. But they were flying G-103s, not high performance ships, and it’s possible that they’d never experienced what I was seeing.

-John, Q3

On Thursday, November 7, 2013 2:05:07 PM UTC-5, Steve Leonard wrote:
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