The document at the following reference may be of interest
- in particular pages 28 - 30

https://www.gliding.co.uk/bgainfo/cl...uments/aerotow
notes.pdf

also see my edit re the tow plane diving

At 17:24 17 September 2006, John Smith wrote:
A simple question to all the participants in this thread
- How many off you have actually experienced piloting
a tow plane when the glider has kited behind you?
As a tow pilot who has had it happen at 500 feet agl
and did survive I can state that it is not just the
angle of the rope but also the highloads imposed that
prevent release of the rope by the tow plane. This
affects all types of release. You have a tow plane
'most likely at full power' trying to dive at a steep
angle and a glider virtually
winch launching of the back of it - quite a high loading
I can assure you and one that decellerates the tow
plane rapidly. Secondly the upset occurs because of
the upwards load from the glider overcoming the maximum
down load able to be applied at the tow planes tailplane.
This effectively stalls the tailpane in an inverted
sense and the tow plane is actually pitched rapidly
nose down with very little acceleration and indeed
speed. If the rope breaks or releases it is actually
necessary to accelerate the tow plane in its nose down
attitude to gain sufficient speed to pull out of the
nose down attitude.
And NO, I really don't want to experience it again.
With reference to the original question I would strongly
advise the fitting of weak links to all glider tow
ropes regardless of the supposed breaking strength
of the rope used.
PS I do operate at both ends of the tow rope.




At 16:30 17 September 2006, Km wrote:

Doug Haluza wrote:
Oh, my, where to start?

How about with your condisending tude?

No, I'm saying the airplane was designed to handle
flight and landing
loads, based on it's max gross weight. These loads
on the tail are only
a fraction of it's weight. The glider can transfer
most of the lifting
force developed by the wing to the rope if a C.G.
hook is used for
aerotow. An aircraft with a design load limit of 4.4
G's will have an
ultimate load limit 6.6 G's so a glider with a 1000
lb gross weight
could deliver over 6000 lb of force, before the glider's
wings failed.

OK now focus here Doug, the math is not in dispute.
The question is
whether a glider could exert this force while on tow.

After an upset, the towplane will enter an unrecoverable
dive, and if
the rope does not break, the speeds will quickly
increase beyond
maneuvering speed.

But what makes you think the dive would be 'Unrecoverable'
just because
the tow plane is past its manurering speed?

You can't pull out of the dive if the glider is still
attached to your
tail by a rope that won't break. And if you have a
Schweizer hook on
the tail, it may not release after the upset because
the pull is
greater and may no longer be straight back. There
have been several
cases of upset where the tow pilot could not make
the hook release, and
the dive would have been unrecoverable if the rope
did not break.

Completely true statement.But, as the nose of the tow
plane drops, this
would change the angle on the release would it not?A
couple of local
pilots tried this (At altitude of course) and found
this to be the
case.Now at low altitudes, all bets are off of course.This
is the
beauty of the tost hook.

Even if you tow with a Tost hook, you still need to
react and operate
the release.

Doesnt this go without saying?
I have to take issue with your previous post where
you implied that a
pilot could get away with aerobatics in a Super Cub
as long as he wasnt
doing 'Tailslides'.To coin your phrase this is 'Ignorant
Thinking'.You
should read my response to Baron 58Yankee on this one.I
think that any
aerobatics in a Super Cub should be discuraged.
Most Respectfully Yours,
KMU