CG hook on aero tows??

In the flat lands,
if the tug wings are on or above the horizon, you're too high, IMHO.

I think you got something reversed. The lower the glider goes, the
higher above the horizon the tug will appear to be.

I hate it when I do that. Yeah, I *meant* below the horizon. Thanks for
the catch.

Tony

On Mon, 12 Jan 2004 11:42:08 -0500, Tony Verhulst
wrote:


In the flat lands,
if the tug wings are on or above the horizon, you're too high, IMHO.

What we teach in the UK is to keep the tug in the correct position on
the canopy, not a position on the horizon.

The position of the horizon changes depending on the terrain, the
position of the tug on the canopy doesn't seem to.

On the original subject I can add some experience.

Some years ago (mid 70s) I had a flight in a Ka6E on aerotow and got
slightly too high just after take off. I was surprised and alarmed to
discover I needed to put the stick on the front stop to start the
glider descending - slowly. A little higher or a bit of bad luck and
I could have joined the tug upset statistics.

This was with a CofG hook.
The tug was not powerful - an Auster.
It was one of my first flights on type.
I was a reasonably experienced pilot - 400-500 hours, Gold C,
Instructor, current on Aerotow.
Fine weather, light wind.

I still remember - nearly 30 years later - the feeling of helplessness
as I sat with the stick on the front stop, waiting for something to
happen - and yes, I was just about to release when it started going
down.

I'm not fanatic about this and I would launch on the CofG hook if
there was no alternative - or a good reason but if I was in charge of
a club that did aerotow all the club gliders would have nose hooks and
use them.

Chris Rowland

if you are towing that low out here in the summer time... you are going to
find yourself in the wake from time to time.. and being in the wake
increases the drag on the tow plane and reduces the climb rate and increases
the down pull, forcing the tow pilot to push on the stick..

we "train".. tow plane on the horizon.. granted there are hills/mountains
all around so the horizon is a "relative" term... keep all 3 wheels of the
tow on the same horizontal line.. the tail wheel between the mains.. works
just fine for the Pawnee 235

if you are low.. "to just above the wake".. it is more difficult for the tow
pilot to see you in the mirrors.. and he may think your going down to box
the wake. Also, with summer thermals.. the tow plane enters the thermal
200ft before the glider, and a 400fpm rate of climb jump to better than
1000fpm for the tow plane.. and you are in the wake.. granted.. in a couple
of seconds or so.. you'll be in the thermal and going up just as the tow
plane exits it and hits the sink

it's hard enough fighting the thermal drafts.. but to add an unplanned
excursion into the wake? a couple of those.. and at 2K AGL.. I'm off...

BT

"Robert John" wrote in
message ...
I don't think the positition of the horizon should
make any difference. In mountains it's irrelevant
and different tugs will climb at different rates -
a powerful tug will be more pitched up and adopt a
higher position relative to the horizon than a low
power one (relative to the thrust line, the prop-wash
and the best position of the glider just above the
prop-wash).
One of the advantages of being as low as possible is
not just the extra time that it takes to get to 'upset'
position (which is small) but the fact that you are
less likely to lose sight of the tug in the first place.
Once you can't see the tug, things can go wrong very
quickly.
I've flown in Australia with their low tow and whilst
I'm sure each method has its merits, I am personally
much more comfortable with the UK position, don't like
having to transition through the propwash at low level
and find that teaching a 'correct' position that looks
almost identical to the position on the ground before
All Out is easier too.
Rob

At 16:48 09 January 2004, Eric Greenwell wrote:
Andy Durbin wrote:

As a US instructor I have flown with many pilots that
received their
initial training from other instructors. I have often
been surprised
at the tow position taken by such pilots. I usually
urge them to keep
lowering the tow position until they feel the wake,
then to move just
high enough that the wake is not a factor. That tow
position may be
10 or 15 ft lower than that initially used.

Where is the towplane, relative to the horizon?

A pilot flying a high high tow has less time to react
to a potential
upset than one flying the UK recommended low high
tow. The fact that
US pilots seem to be trained to use high high tow
may explain why tug
upsets continue to happen even when a nose or forward
hook is used.

10 or 15 feet doesn't sound like it would give much
extra time, not like
the low tow position Australia uses.

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Eric Greenwell
Washington State
USA

we "train".. tow plane on the horizon.. granted there are hills/mountains
all around so the horizon is a "relative" term...

I've also been on tow on really hazy says when there was no visible horizon.

keep all 3 wheels of the
tow on the same horizontal line.. the tail wheel between the mains.. works
just fine for the Pawnee 235

Yup, reference to the tow plane, that's the ticket. Behind the Birddog,
I like to fly tow so that the horizontal stabilizor lines up where the
gear and wing struts join the fuselage.

Tony V.

With the supercubs and Robin DR400s at LGC the tug
wheels are generally on or a little above the horizon.
I wouldn't generally be so low as to be catching the
wake though in strong thermal conditions I can see
that you might. If I tow through a strong thermal
I'm going to release anyway!
Rob

At 18:00 09 January 2004, Eric Greenwell wrote:
Robert John wrote:

I don't think the positition of the horizon should
make any difference.

It's the position I typically use, so I'm trying to
get an idea of how
different it is from what I normally do. Unfortunately,
I can't go out
and experiment right now, with a foot of snow on the
runway!

So, with a 180 hp Super Cub or Pawnee, say, is the
tug canopy on the
horizon, the wing root, wheels, or maybe the tug is
an entire 'tug'
distance above the horizon?

In mountains it's irrelevant
and different tugs will climb at different rates -
a powerful tug will be more pitched up and adopt a
higher position relative to the horizon than a low
power one (relative to the thrust line, the prop-wash
and the best position of the glider just above the
prop-wash).

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Eric Greenwell
Washington State
USA