Glider Handling on Tow

On Tuesday, November 5, 2013 11:10:33 AM UTC-7, John Carlyle wrote:
A question for any aerodynamicists out the why does low aero tow speed adversely affect the handling of a glider so drastically?



Occasionally I’ve received an aero tow in my LS-8 (dry) at 55 kt (minimum recommended aero tow speed is 54 kt). The plane is heavy and unresponsive at that speed; it’s an extremely stressful experience! But once off tow the same plane handles like a dream at speeds down into the upper 30 kt range.



Before anyone asks, yes, I do immediately ask the tow pilot for 10 kt more speed - right now! I’d just like to understand what the root aerodynamic cause of the poor handling might be.



-John, Q3

Not sure how different the experience of the flapped ships is, but the biggest complainers behind our Pawnees seem to be the D2 and LS8. From a wingtip video, I eyeballed the towrope angle and thought that its vector was below the fuselage center line. however, the down-wash theory is also certainly plausible. The dynamics of aerotow are certainly not simple and the problem could be a combination of several effects.

Mike