C of G hooks do not create a problem on tow - for anyone
who does not find himself with a significant degree
of pitch up (sorry can't give a figure in degrees,
it will vary according to type) relative to the tow-plane's
flight path.

I agree that competent pilots (whatever that means)
are less likely to find themselves in that position.
However, given that it takes less than 0.5 seconds
for the necessary amount of pitch up to occur, and
that pitch up can be caused by either a gust, an inadvertant
elevator input by the glider pilot, or an unexpected
attitude change by the tow-plane, I don't think anyone
is 'competent' enough to guarantee that it can never
happen to them.

Changing the subject just slightly; the use of 'low'
high tow, refered to several times in this thread,
does not really help because:

1. The 'few feet lower' position adds less than half
a second to the time the 'upset' takes (given a 'normal'
lenght rope of just under 200 feet); usually not enough
to make any difference to the outcome.

2. The slight upward angle of the force on the rope
increases the instability of the situation and means
that a slightly smaller pitch angle is needed to set
the whole thing off.

3. The close proximity to the tow-plane's prop wash,
and occasional indvertant excursions into it, may well
provide the trigger mechanism that causes the unwanted
pitch movement.

I will post no more on this subject until and unless
someone actually comes up with some new flight test
reports.

However, I am prepared to offer my services as an expert
witness, to the estate of any tow-pilot who is killed
in a 'tug upset' accident whilst towing a glider on
a C og G hook.

Chris Rollings

At 03:18 09 January 2004, E. A. Grens wrote:
CG hooks on tow do not create a problem for competent
pilots. It is only
necessary to fly the towed glider, as in close formation
flying, without
depending on the tow hook to do a lot of the work for
you. Of course, very
short tow ropes can make any tow difficult. Both my
own glider, a Phoebus
A-1, and the DG-101 I frequently fly in my club, have
only CG hooks. With
reasonable tow-rope length I have never found CG hooks
to present any
problems. But, do keep the trim full down on take-off.

Ed