High tow vs. low tow for rough tows (long)

(Mark James Boyd) wrote in message news:3fcfbbf3$1@darkstar...
While towing for Hollister, I noticed their instructor
really liked to practice slack line.

So for my flight review in Avenal yesterday, we did a bunch
of slack line corrections. We did them during one tow,
but broke the rope. 150' of rope ($12), two schweizer rings ($20),
one tost ring ($35), a carabiner (sp?), two half-wiffle balls,
and a short section of "weak link" then back-released from
the 2-33. It plumeted swiftly into a thankfully barren
plowed field below.

A few tows later, we mentioned to the tug pilot we were gonna
try slack line again. He wised up and took off the weak
link assembly ($68) leaving just wiffle and a $10 schweizer
ring.

After a dozen more slack rope practice tries, we broke
that rope. The ring and 10' of rope back released and
plumetted into another (thank god) barren field.

I'm sure some tractor pulling a tiller will grind some metal
at some point and we may get them back.

I thought about slack line. The real problem isn't
too much pulling, it's the "snappiness" with which the
slack line comes out.

It strikes me that on low tow, as slack line pulls out,
it allows a lot softer recovery. When slack comes out,
the tail of the towplane is pulled low, giving some
dampening. Next the towplane slows a little from the
drag, also good. On high tow, neither of these is true.

Sure, sure, I've read very careful use of spoilers and
yawing the sailplane away from the slack are tried and true
methods. However, even using these, there is still some point
there is so much slack you are going to break the
rope no matter what. A friend mentioned during his
first flight to try to get in wave, he with the experienced
instructor broke three ropes before succeeding.

My question is to those who have towed through rotor.
Have any of you tried low tow and high tow and would
care to tell us if you've found a difference in the
number of rope breaks?

How about the idea of towing low and to the left of the
tug? Ignore for the moment that it would annoy the tug
driver to do this on purpose (except maybe if torque
and p-factor now meant he could just leave the rudders
to flop about). Also ignore for the moment it is
drag inefficient. Would this reduce the possibility
of slack line and/or improve recovery chances even more?

How about other dangers? If the rope breaks on low
tow how would you feel about having it
fly over/around top of the wing/elevator/rudder?
Anyone have this happen?

I'm especially interested in the experiences of wave
pilots and those towing through super heavy thermals...
but armchair analysis is also invited :-]


Our club,Valley Soaring Club in SE NY and the prior 2 commercial
operations have
used low tow exclusively for more than 30 years. It is used in Oz as
primary. Not sure where else.
Our experience is that slack rope situations are almost totally non
existant. Most all of these result from descending from a higher
position.
We teach and fly in a position just below( almost touching the wake).
In this position, the rope is in line with the natural trailing
position behind the tug. As a result, if the rope is released from the
tug, it falls below the glider and will back release in most cases.
Even if way too low the rope would normally just trail over the top of
the glider. Yes the ring could hit the canopy or other part of the
glider.
Advantages we see:
New students fly the tow without help within 2 or 3 tows. Position is
easy to view, evaluate and adjust.
Glider is on thrust line of tug- efficient, less trim drag, no trim
change.
Nobody ever dove a tug pilot into the ground in low tow.
Slack is virtually not a factor. Easily and gently corrected. No
broken ropes. I have not had a broken rope in 10,000 low tows at
glider end and about 4000 at tug end.

Myth: you can get too low and pull tug tail down stalling him- We
tried and found we could actually go slower in control towing with
Super Cub with glider hanging way low than we could with glider off.

Myth: Rope wil tie itself around wing and disble controls if released
at front. Show me a rope that can go upwind in a 60 mph headind.

Conclusion: It is worth learning to do right. Tug pilot needs to be
aware you will be doing something different(he may need mirror
adjusted differently).

OK now all the experts can shoot holes in my comments- go for it.
UH