We have had several people writing that they have launched heavy glider X
with a low powered winch. I have done it and so have many others, but this
is still not a good idea. There are serious dangers involved.

The best way to look at it is to consider power demand and supply. The
winch engine should be able to supply all the power the glider demands. If
the glider demands more power that is available by pulling up hard, the
airspeed will decay quickly. If the pilot knows this is going to happen, he
can manage it by controlling the pitch attitude carefully. If he doesn't
expect it, the airspeed will decay so quickly that a very dangerous
situation will develop.

The attempt to launch gliders with a low powered winch gets into who is in
control of the launch. I think it goes without saying that who controls the
launch should not be in doubt. The majority view is clearly that the winch
driver should be in charge.

With a low powered winch, the winch driver is in charge early in the launch
but as the glider steepens the climb, the power demand exceeds supply and
speed control shifts to the glider pilot who now must control airspeed with
pitch since the winch is at full throttle. As the glider rises still
further and power demands lessen, airspeed control shifts back to the winch
driver who must reduce power to prevent over speeding the glider. There
are lots of ways this scenario can go badly wrong.

The other area where a low powered winch can cause problems is in the
initial acceleration. The German Aero Club specifies the maximum distance
that a glider can use to reach flying speed to determine the minimum winch
power. Specifically, under all conceivable wind, density altitude and
weight conditions, a glider must reach Vr (rotation speed) in 40 meters or
less - there is no minimum specified. This is a very intelligent
specification. The concern driving this spec is that should a glider's wing
drop to the ground before reaching flying speed, the resulting ground loop
will be very ugly and quite possibly fatal for the glider pilot.

These concerns and the desire to get the highest launch possible, has driven
winch horsepower higher and higher in recent years. Shortening the
accelerate to Vr distance has a powerful effect on the launch height
achievable. Many powerful winches have shortened this to less than 20
meters.

To summarize, I am advocating generous power reserves to permit the winch
driver to maintain control of the launch and to insure the glider reaches
flying speed before a wing can drop.

Bill Daniels