Ground launch and the incremental vanishing of soaring

In article ,
Larry Pardue wrote:

I keep a reel in the back of my Ford Escape that has the 1500 foot launch
rope on it. After a launch the rope is reeled in by an electric motor on
the reel. Very tidy and easy. I average around 1,200 feet on the very long
ramp at Hobbs with a PW-5. Rarely do I have to take a relight but when I do
I feel like I can stand the 35 cents or so it costs to take another one.
Those $40 contest tows are quite a shock for me.

I am learning more about auto-launch, and it sounds fantastic.
And the lighter gliders are seeming more and more appealing
as I learn more. A 155# or even 300# glider with a yuppie
at 170# is gonna accelerate much better, perhaps well enough
to simply winch launch off a truck (with a winch mounted in the
back).

I've heard numbers of 100-300# of tension for the light gliders
on winch or auto tow. Does this sound about right?
This certainly meshes with the numbers I would expect...
--

------------+
Mark Boyd
Avenal, California, USA

"Mark James Boyd" wrote in message
news:404cea0d$1@darkstar...
In article ,
Larry Pardue wrote:

I keep a reel in the back of my Ford Escape that has the 1500 foot
launch
rope on it. After a launch the rope is reeled in by an electric motor
on
the reel. Very tidy and easy. I average around 1,200 feet on the very
long
ramp at Hobbs with a PW-5. Rarely do I have to take a relight but when
I do
I feel like I can stand the 35 cents or so it costs to take another
one.
Those $40 contest tows are quite a shock for me.

I am learning more about auto-launch, and it sounds fantastic.
And the lighter gliders are seeming more and more appealing
as I learn more. A 155# or even 300# glider with a yuppie
at 170# is gonna accelerate much better, perhaps well enough
to simply winch launch off a truck (with a winch mounted in the
back).

I've heard numbers of 100-300# of tension for the light gliders
on winch or auto tow. Does this sound about right?
This certainly meshes with the numbers I would expect...
--

------------+
Mark Boyd
Avenal, California, USA

The maximum rope tension is usually determined by the glider maker as stated
in the ground launch weak link strength specification. Typically max gross
weight times 1.2 to 1.5. Check your POH. That said, the typical line
tension at the glider is roughly equal to the GW for an optimum launch.

It's been my experience that smaller gliders don't do as well as larger
gliders on ground launch. Maybe it has something to do with Reynolds
numbers or maybe the weight of the cable as a percentage of the glider's
gross weight.

Bill Daniels