If you're only getting 33% of the rope length, yours is a low
performance winch operation. If you optimize it, 45% or so is
achievable in no-wind conditions. A 10 knot wind can boost that over
50%. Again, I'm saying this is for gliders with better than 30:1 and
rope tensions equal to the weight of the glider. Below 30:1, achieved
height falls off a lot.

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