Ground launch and the incremental vanishing of soaring

"Larry Pardue" wrote in message
...

"Eric Greenwell" wrote in message
...
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'll bet! Do you tow anything heavier than the PW5, and how does that
work out?


I used to tow my Mini-Nimbus with a 140 HP Ford Taurus wagon. I actually
got better tows with that setup, I think because of a more favorable CG
hook
position, but I never car-launched with much water because I was HP
limited.
Instructions to the tow driver were "floorboard it until I get off."
Launches with a 1,500 foot rope were usually to about 1,400 feet. I'm
sure
my present 200 HP vehicle would launch an 1,100 lb gross glider with no
problem but I would want a stronger rope than my present 1/4 inch dacron
(Wings and Wheels $270). I have launched a friend's Ventus a few times
with
the Escape and he gets real good launches. With the Mini-Nimbus and a
well
worn rope, I would get some rope breaks.

Larry Pardue 2I



Folks who do this know, ground launch is CHEAP FUN! With a good operation,
it's FAST too.

One way I have thought about for airports that share runways with power
traffic is to put the winch on a truck. When the glider is ready, drive the
truck mounted winch down the runway paying out the cable, quickly launch
glider and suck in the cable before it falls to the ground, then drive the
winch clear of the runway and back to the start point for the next launch.
That way, the winch, cable and glider are on the runway for only a couple of
minutes. It also reduces the wear on the cable significantly while keeping
the cable away from the runway edge lighting.

Bill Daniels

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...
--

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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

We aero tow off a county run airport with an operating permit.. when they
rebuilt the airport from one dirt strip to 2 paved parallel, they used our
"traffic count" to justify the FAA $$, and they built a "power" and "glider"
runway.. no lights or other obstructions on the glider runway, and the
infield is bladed level with the runway.. Jean NV


BT

"Mark James Boyd" wrote in message
news:4046baa4$1@darkstar...
I spent a good portion of the past few days looking into
auto-tow launching. After some fairly extensive
searching, I found that, as far as I can tell, nobody has
used auto-tow OR winch launch at a public airport
in four years.

LaGrange-Callaway GA (SES) used to do winch, and according to the airport
manager that was stopped there because it interfered with the
traffic there.

Bend, Oregon couldn't remember when auto-tow was used last, and
after my call the city engineer suggested perhaps they should change the
"auto-tow by special request" to "no auto-tows allowed."
So my inquiry actually perhaps has now closed even the possibility at that
airport.

Does anyone know of a US public airport that has allowed auto-tow
in the past five years? How about winch?

This was quite troubling to me. It seems public airports have
rejected ground launch entirely. I wonder when aero-tow out of
public airports will completely disappear as well, including
aero-retrieve.
Public airport managers certainly can prohibit (in writing) a person
from walking on the runway and hooking up a towline. I suppose a
careful reading of just about every airport policy document already
prohibits this.

I hadn't really believed this until I talked to four airport managers.
Without a clear YES from the Calif. public airport insurance "pool",
and no overriding benefit to the airport, it looks like (non-self launch)
gliders can generally use public airports legally only as
landouts to trailer from. Sure, sure they turn a blind eye to
the occasional aero-retrieve, but if anything happened, the
"walked on the runway" illegality would absolve the airport of any
liability...

Soaring departures from private and military/CAP airports only?
I guess that's pretty much it. And if most gliders sold are mostly
motorgliders, I'm guessing even tow will become more rare.

Does anyone know the numbers of public airports that used to
have tow or ground launch operations years ago vs. today?

Hmmm...I was a bit surprised at how little the "public" airports
support soaring. Well, at least they make good landouts...








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Mark Boyd
Avenal, California, USA