Aerotow with Diesel engine?

Why not two winches; one to launch with and the other to retrieve the cable?
I think I remember this being done years ago. If the drag chute is big
enough, the retrieve winch should be able to return the entire cable. I
wonder how fast two setups (4 winches) could launch a fleet?

"F.L. Whiteley" wrote in message
...

"Kirk Stant" wrote in message
om...
(Mark James Boyd) wrote in message
news:41818652$1@darkstar...
Steve Hill wrote:

I'd really like to see what the actual costs are for a club to
purchase
a
good winch.

The "street" has spoken. There are NO winches in California.
And the ones I researched that were closest were in Arizona or
Washington, and aren't getting anywhere even remotely close to
50 launches a day.

I haven't been to Washington yet, but I have talked to the club there
and they were closed for a good part of last winter (0 launches).

Would a winch in CA do well? I dunno. At Avenal, there are
days when it would be fine, but then again there are
a lot of days or times of the day when a higher tow or further
away is better. And of course I've had 4 aero-retrieves.
Try that with a winch


The Prescott (AZ) Soaring Club does well with their winch, apparently.
Down here where I usually fly at Turf (just west of Phoenix), we
rarely aerotow higher than 1500', I think my usual release altitude is
about 1200' just off the end of the runway into the house thermal -
ideal for a winch! Of course, this makes for a pretty quick cycle
time with a couple of Pawnees, and we would really need a double or
triple drum setup to get a race grid off rapidly, but it sure would be
fun to watch!

Kirk
66
A single drum winch is the poorest of compromises in effeciency with only
cost being the overriding factor. There is simply no reason to drag one
rope at a time and doing so can make the entire process more tedious and
dampen enthusiasm. Only one thing matters to private owners on the
ground,
and that's launch rate. For wide adoption, a two drum winch works well.
For a large operation, two two-drum winches provide high availability and
redundancy, portability is off-site operations are anticipated.

Frank

It's doable and is done at the Long Mynd, Midland GC,
http://www.longmynd.com/ along with bungee launching.

Spectra's 'float' might make work pretty well on a long run.

Frank Whiteley

"Bob Salvo" wrote in message
...
Why not two winches; one to launch with and the other to retrieve the
cable?
I think I remember this being done years ago. If the drag chute is big
enough, the retrieve winch should be able to return the entire cable. I
wonder how fast two setups (4 winches) could launch a fleet?

"F.L. Whiteley" wrote in message
...

"Kirk Stant" wrote in message
om...
(Mark James Boyd) wrote in message
news:41818652$1@darkstar...
Steve Hill wrote:

I'd really like to see what the actual costs are for a club to
purchase
a
good winch.

The "street" has spoken. There are NO winches in California.
And the ones I researched that were closest were in Arizona or
Washington, and aren't getting anywhere even remotely close to
50 launches a day.

I haven't been to Washington yet, but I have talked to the club
there
and they were closed for a good part of last winter (0 launches).

Would a winch in CA do well? I dunno. At Avenal, there are
days when it would be fine, but then again there are
a lot of days or times of the day when a higher tow or further
away is better. And of course I've had 4 aero-retrieves.
Try that with a winch


The Prescott (AZ) Soaring Club does well with their winch, apparently.
Down here where I usually fly at Turf (just west of Phoenix), we
rarely aerotow higher than 1500', I think my usual release altitude is
about 1200' just off the end of the runway into the house thermal -
ideal for a winch! Of course, this makes for a pretty quick cycle
time with a couple of Pawnees, and we would really need a double or
triple drum setup to get a race grid off rapidly, but it sure would be
fun to watch!

Kirk
66
A single drum winch is the poorest of compromises in effeciency with
only
cost being the overriding factor. There is simply no reason to drag one
rope at a time and doing so can make the entire process more tedious and
dampen enthusiasm. Only one thing matters to private owners on the
ground,
and that's launch rate. For wide adoption, a two drum winch works well.
For a large operation, two two-drum winches provide high availability
and
redundancy, portability is off-site operations are anticipated.

Frank

For experience with retrieve winches see the Long Mynd site, they use one all the time - Bill Dean should be able to tell you more.

Rgds,

Derrick Steed

In article , Bob Salvo
writes
Why not two winches; one to launch with and the other to retrieve the cable?
I think I remember this being done years ago. If the drag chute is big
enough, the retrieve winch should be able to return the entire cable. I
wonder how fast two setups (4 winches) could launch a fleet?

This is the set up the Midland Gliding Club has used for at least 30
years, the two cables join in a device that used to be an iron triangle,
but the present gizmo is a lot lighter.

It gives a very good launch rate with an experienced driver on each
winch.

But its not universally suitable...
--
Mike Lindsay.

Each end of the runway has been resurfaced but the middle is the original
concrete, patched where necessary. Aerotow is no problem, though I think one
landout pilot (with a brand new glider) decided against an aerotow retrieve
because of possible stone chip damage.

Piano wire is a distant memory - our nearly new Skylaunch winch gives very
smooth and consistent launches.

"F.L. Whiteley" wrote in message
...
Did they ever remove the broken up concrete or resurface the runway? It
was
in a state 25 years ago. Would have been lethal to aerotow there then.

Are you still using that old piano wire winch with the big 'drum'?

Frank

"Chris Reed" wrote in message
...
My club (Rattlesden in Suffolk, England) operates both winch and aerotow
simultaneously. From 8 years flying there I'd say that the most
important
factor for winching is the layout of the site. If it is possible for
aircraft to land without interrupting winch launching then it's very
satisfactory as a launch method, and you might consider moving to winch
only.

Our site is more difficult - an ex WW2 USAF airfield with a main 3,000
ft
runway and a shorter 1,600 ft cross runway. We can only winch from the
main
runway, which means a crosswind component on the majority of days. In a
typical (!) single-seater like a Grob Astir you could expect 800-1,000
ft
on
a 90 degree crosswind day, and 1,400 ft plus with a 20kt headwind. A
reasonable soaring day with, say, a 30 degree crosswind at 10kt should
give
you around 1,300 ft. From this, if you are a reasonably competent
soaring
pilot, I estimate you have a 50/50 chance of soaring. This increases if
you
can delay the launch until "your" cloud arrives over the winch.

Frank Whiteley makes some highly relevant points:

3. Launch rate is important. With our single drum winch, I can drive
a
launch, drag the wire, return to the winch, and launch again with an 8
minute cycle time on a 5000ft run. If the headwind is good, I can
have
both
CG equipped two-seaters in the air at the same time. When there's
lift,
we
launch about every 15 minutes, giving each training sorty about 20-25
minutes. I will chastise anyone who is not ready to launch when the
wire
arrives. Do your ground school after hours or week nights, not at the
launch point.

All this is very true, but on a restricted site the launch rate also
suffers
from aircraft landing on the main run, used for winching. Trainees and
early
solo pilots will use the main runway most of the time, as will the tug
aircraft. Practice winch failures at low hight will land straight ahead.
The
sudden appearance of three gliders will require at least one to use the
main
runway. All this means you need to be well organised, so as to clear the
gliders waiting to launch if necessary.

Given these potential frustrations of the winch launch, unnecessary
delays
by pilots waiting to launch are to be avoided at all costs.

We use a Skylaunch twin drum winch with braided wire cable, and on a
good
summer day might achieve 50 launches, 35 winch and 15 aerotow. On an
evening
when instructors fly introductory flights, using two two-seater gliders
launching from the main runway and landing on the cross we have achieved
16
launches per hour (6 min flights), winching only.

6. If you get a ground launch endorsement in six launches, you've
been
cheated. Don't expect to exercise your privileges at my club. There
are
some insidious things about ground launching that could bite you, and
you
will practice and understand avoiding them. They can't be exercised
in
six
launches. No matter how many winch launches we've flown or driven,
we're
still learning. I, for one, haven't seen it all, nor do I care to.

Absolutely! From memory from the BGA instructor's manual you need to
learn
at least:

1. The ground run (quite different from aerotow);

2. A safe transition to the climb, so that a 50ft cable break doesn't
leave
you with insufficient energy to push over, regain flying speed and round
out. Correct use of the airbrakes in this situation is critical.

3. Recovery from a low cable break with a straight ahead landing.

4. Recovery from an "awkward" height cable break, where you can't land
ahead
but have too little height for a normal circuit.

5. Recovery from a mechanical failure of the winch (usually a gradual
loss
of power).

6. Signalling too fast and too slow, and what to do if the winch doesn't
respond.

7. Laying off for crosswinds to prevent the cable falling off the runway
on
release.

8. Avoiding over-speeding and under-speeding. This includes
understanding
the changes in stresses on the glider throughout the launch and the
symptoms
of an impending stall on the wire (very nasty!).

9. Stalling and spinning from launch failures - these will be simulated
at
height, e.g. dive to 70kt, pull up into 45 degree climb, as speed falls
to
around 50kts instructor announces cable break. It takes a second or two
to
react and push over, by which time speed will be down to 30 kt or so. If
you
stop the pushover at the normal gliding attitude and turn immediately
most
gliders will roll smoothly into a spin with no warning signs - don't try
this on your own if you haven't been well trained on spin recovery!

10. Inadvertent launching into cloud.

This list may sound alarming, but we regularly solo students on the
winch
with, say, 7 hrs flying time. However, there's no way these matters can
be
covered in a handful of launches.

The UK consensus seems to be that winch launching is as safe as aerotow
but
*only* if pilots are well trained.

So why do we aerotow as well? Obviously, some aspects of pilot training
require more height than a winch launch will give. More important, for
pilots setting off on a task an aerotow takes you to the lift at a
height
where it's easier to work. Less mental energy used to get started means
more
left over to complete the task.