Ground launching equipment question

I agree about the chute.

All the winch launching parachutes I've seen (and the principle should
be the same) are constructed roughly as follows:

1. Take four squares of material (lozenges might be better, and possibly
some curvature in some of the sides - you'd need to experiment).

2. Attach one corner of each to the other four to form the apex of the
chute. The cable to the glider goes to this apex.

3. Sew the squares together along (for each) the two sides which meet at
the apex (think jellyfish?)

4. Connect the four free corners by tapes or ropes about 3 or 4 feet
long to the cable connected to the tow car. Most chutes I've seen have a
heavy duty tape stiched from the apex of each square to the free corner,
then continuing to form the junction to the tow car cable.

Chutes like this stay closed so long as the cable is under more than
minimal tension.

You'd need to experiment - maybe start with four handkerchiefs and some
pins to see if my description translates into something usable?


Neil MacLean wrote:
At 18:01 02 November 2007, John Cagle wrote:
The chute kept fully opening the
first day I used it. You can see it in the video that
I have on my web
site. http://www.caglesonline.com/video/autotows.wmv
Since that day I have
increased the 2 m connecting cable to 4 m. It does
a better job as you can
see in the next video taking the same day and place
that jims glider ground
looped. http://www.caglesonline.com/video/07fallroachlake.wmv

It looks from the videos as if the towing cable is
split in four and looped over the chute so it is trying
to keep it closed only because of the tension in the
cable. I think the chute is almost bound to open with
this arrangement. In all the ground launch cables I
have seen and used - for both winch and auto tow -
the strop attached to the glider goes directly to the
apex of the parachute so that the chute itself is part
of the cable and is kept closed by its own tension.

And 65 or 70 mph seems far too fast. At any reasonable
launch angle the glider airspeed is considerably more
than the tow car speed so for a good launch at say
55 or 60 kt into a light wind, the car should be doing
no more than 30 or 40 mph.

Neil