On Sun, 4 Jan 2004 16:53:58 -0700, "Ted Wagner"
wrote:

A few seconds into take-off roll today in a Pilatus B-4, while applying left stick to correct for a dipping right wing, the right wing suddenly dipped all the way into the ground. The glider lurched to the right, and a second or two later popped up into the air, a good 20 feet up and 30 or more feet out to the side. By that time I had full left rudder in addition to full left aileron, so the glider recovered rather quickly, and I was able to bring it to normal take-off position right about the time the tow plane started to climb. I was amazed he had maintained his heading directly down the runway. The winds were light and variable. It was my ninth flight on the B-4.

After landing, the tow pilot apologized, saying it was his fault -- something about the wake turbulence. But I'm still puzzled about what, if anything, he did wrong; it looked like a completely normally take-off roll to me.

I had thought that maybe a sudden tail wind had reversed the effective correction of my aileron deflection during take-off, causing the right wing to dip harder instead of leveling off. Does this make sense to anyone with more experience on an aircraft like the B-4?

Also, I'm curious to know how much the CG hook location on the B-4 contributed to the squirrelly sequence of events after the right wingtip hit the ground. How many 15+ meter gliders have CG-only hooks? Are such exciting events more commonplace with CG hooks?

Other than the wobbly tows, I'm loving the B-4, it's the first 15-meter single-seater ship I've flown, and the first with retractable gear...

~tw

How long was the rope?

Most of the towplane wake turbulence or whatever problems go away if
you use a 250 foot rope. Lots more time in the event of a pitch up and
less likely anyway due to lower energy in the wake turbulence.

I once saw three gliders damaged in one day at Waikerie(all unflyable
the next day) due to aero retrieves out of fields with short ropes and
nose hooks. Problem with a nose hook is that if things get out of hand
and you release they instantly get a lot worse.

Short ropes are deadly. It is the angle that counts. Longer rope =
smaller angle = recoverable situation. I find this so bleeding obvious
after observation, experience and thinking about it that if I was an
insurance company I'd refuse all claims for ground loops or towplane
upsets that used a shorter than 250 foot rope.

Anyway I gave up aerotowing and bought a TOP.

Mike Borgelt