Ain't no doubt about how quickly the tug gets upset when the glider decides
to fly hither and yon.

My event involved a highly experienced retired FAA guy with type ratings in
every aircraft imagineable. It was his first flight in a borrowed HP-14
and, during the departure turn at about 700' AGL he flew high and wide to
the right, outside of the turn. Before I could reach the release lever,
he'd turned hard left and dove across the tail of the Pawnee wrapping the
tow rope around his left wing and, after it cut the top and bottom skins of
the wing clear to the spar, cutting the rope in two in the middle. The
final yank on the rope caused the tug to yaw hard right and pitch slightly
up (from about 45 degrees down).

Not realizing how close he'd come to killing us both, he proceeded to have a
nice 4-hour flight. After landing he asked our line guy to help with
derigging. That's when Steve called him to the left side of the glider and
pointed out the damage.

I had a few words with him, too.

"Colin Wray" wrote in message
...
Chris Rollings wrote:

Third test: Terrier Tow-Plane, K 8b on C of G hook. I pitched the glider
about 25 degrees nose up. The glider continued to pitch up fairly rapidly
(as at the start of a winch launch) and substantial forward movement of
the
stick only slightly slowed the rate of pitch. The glider achieved about
45
degrees nose up, speed increased rapidly from 55 knots to about 75 knots
and the glider was pulled back towards level flight (again as at the top
of
a winch launch). I released at that point. The entire sequence of events
occupied a VERY short period of time (subsequently measured as 2 - 3
seconds). The Tow Pilot reported a marked deceleration and start of
pitching down which he attempted to contain by moving the stick back; this
was followed immediately by a very rapid pitch down accompanied by
significant negative â?oGâ??. The tow-plane finished up about 70 degrees
nose down and took about 400 feet to recover to level flight. We both
found the experience alarming, even undertaken deliberately at 4000 feet.
Our conclusion was that the combination of the initial pitch down and the
upward deflection of the elevator caused the horizontal
stabilizer/elevator
combination to stall and the abrupt removal of the down-force it provided
caused the subsequent very rapid pitch-down and negative â?oGâ??.

I was the pilot of a tug involved in exactly the scenario described by
Chris above. The culprit was a K6 using a belly hook, and the only
reason I am here to tell the tale is that it occurred at 400ft. It was
actually a dual tow with the K6 on the short rope and a K13 on the
long rope in low-tow position. The K6 had recovered from some earlier
excursions, but all seemed to be going well before it happened.

The "up-ending" was instantaneous, there was no way to have reached
any type of release before the rope broke, and in any case I can
assure you that when descending vertically on full throttle at 400ft,
your first reaction it to close the throttle.

Our CFI in the K13 said he hadn't seen the underside of a PA18 in plan
form quite so close before.

In those days we used to store spare ropes and things behind the rear
seat of the PA18, and my situation was not improved by the whole lot
coming forward and landing on my head and all over the cockpit.

A good friend of mine later died towing a K6 with a PA18, which
incident quite probably was the trigger for Chris' investigations.