Ground launching equipment question

Last weekend our club did some ground launching from a nearby dry
lake. I had two very successful launches using our "cheap" 1800'
rope. With the cheap rope we don't use a parachute on the cable.
When I tried to launch with the 3000' spectra rope, equipped with a
parachute, the chute at least partially opened when the glider was
going around 40 knots, and depsite full right rudder, the glider
ground looped to the left. All the pictures I've ever seen
(admittedly very few) of the cable chute used for winch or vehicle
tows seem to show the chute' is completely 'closed' when the rope is
still attached to the glider. I'm sure pilot error had a part in this,
but it really seemed that when the chute opened, I lost what little
rudder authority I had. It also occurred to me that the
Speed Astir verticle stab and rudder is one of the shortest
(vertically) around, and that may have been a contributing factor.
The dust cloud was quite impressive!
Jim

What's the distance between the crown of the parachute and the
attachment to the glider? Should be at least 30 feet.


Dan

On Oct 29, 10:10 am, Dan G wrote:
What's the distance between the crown of the parachute and the
attachment to the glider? Should be at least 30 feet.

Dan

Seemed more like 10 or 15, but certainly less than 30.

wrote:

What's the distance between the crown of the parachute and the
attachment to the glider? Should be at least 30 feet.

Seemed more like 10 or 15, but certainly less than 30.

I winch launch a lot, but have never seen 30. 10 to 15 seems reasonable
to me.

On Oct 29, 7:07 pm, John Smith wrote:
I winch launch a lot, but have never seen 30. 10 to 15 seems reasonable
to me.

That's the general recommendation from Tost (or rather, 10m is). We
used to use less but now use the correct length - it's a lot more
comfortable.


Dan

On Oct 29, 3:30 pm, Dan G wrote:
On Oct 29, 7:07 pm, John Smith wrote:

I winch launch a lot, but have never seen 30. 10 to 15 seems reasonable
to me.

That's the general recommendation from Tost (or rather, 10m is). We
used to use less but now use the correct length - it's a lot more
comfortable.

Dan

Shouldn't the 'chute stay closed though? I'm sure I wasn't clear, but
that was the root of my question.

On Oct 29, 10:35 pm, wrote:
Shouldn't the 'chute stay closed though? I'm sure I wasn't clear, but
that was the root of my question.

Well yeah, it should! The tension through the shroud lines should keep
it closed, but if that's too low the natural tendency for the chute to
inflate overcomes it. That could either be down to a poor design -
I've seen several parachutes that seem to inflate whatever - or
perhaps down to less-than-perfect pilot/winch/car driver technique.


Dan

The chute will open as soon as the force on the rope gets too low. On a
winch launch, this is typically the case if the pilot "follows the rope"
instead of pulling gently in order to rotate into initial climb attitude.

Bert

wrote in message
ps.com...

Shouldn't the 'chute stay closed though? I'm sure I wasn't clear, but
that was the root of my question.

On Oct 30, 1:49 am, "Bert Willing" bw_no_spam_ple...@tango-
whisky.com wrote:
The chute will open as soon as the force on the rope gets too low. On a
winch launch, this is typically the case if the pilot "follows the rope"
instead of pulling gently in order to rotate into initial climb attitude.

Bert

On this (aborted) launch, I was still rolling, both wheels on the
ground. I noted the chute opening in front of other gliders too,
while on the ground. I'd had no problems launching with our non-
chuted poly rope.

On Oct 30, 12:42 pm, wrote:
On Oct 30, 1:49 am, "Bert Willing" bw_no_spam_ple...@tango- On this (aborted) launch, I was still rolling, both wheels on the
ground. I noted the chute opening in front of other gliders too,
while on the ground. I'd had no problems launching with our non-
chuted poly rope.

How springy is 3000 feet of spectra? I imagine that would be more of
a factor for auto tow than winch. I'm speculating that the problem
with the spectra launch is not the parachute itself but the dynamics
of the rope tension. The result may be strongly dependant on how the
tow vehicle accelerarates to nominal launch speed.

Andy