On Jun 7, 7:51*am, GC wrote:
On 7/06/2012 02:45, Chris wrote:

We in europe do winch launching as the standard procedure. Our airfield has
1200m (~4000 feet) paid out cable and we get release height of about 400m
(~1300 feet). With strong headwind we even get 600m, sometimes more. Our
club charges 4,- ? for a launch.

Yes. *Bill Daniels seems optimistic to me. *1 for 3 is about what I'd
expect with a nil to light wind.

It depends on lots of factors: engine power, pilot skills, wind direction
and strength, cable (steel or dyneema), lenght of cable, glider type... and
certainly more. The above numbers are for a double seater like ASK21, steel
cable and moderate headwind.

There have been launches with dyneema cable of 3000m length and release
heights of 1200m. This is a really cost effective way to do aerobatics.

To answer your question: I would think 3000 feet is the minimun for a
reasonable winch operation. However, I have seen fields with only 2000 feet.

The length you need is wire length - not runway length. *The ground run
for a launch is barely 100 yards. *Any more is for landing, launch
emergencies, etc. *Winches are also commonly sited well beyond the
upwind runway threshold. *It's a very flexible launching system.

GC







Chris

100 yards for acceleration is way too long. A 1G acceleration will
get a glider to 40 knots liftoff speed in 71 feet.