Dan G wrote:
We set the trim well forwards to give approach speed in the event of a
launch failure (I am not going to stop doing that, but hypothetically
where would you put the trim for best launch height?),

Agreed - set the trim to suit the day.

and for K21s
winch drivers are briefed to give full throttle the whole way up (winch
is c.300bhp).

That sounds excessive to me. The only glider that gets full power all
the way is an ASH-25.

We launch K.21s on a 240 hp diesel winch (Deutz air cooled V8) and never
reach full power in normal circumstances. If an ASK-21 or G.103 is being
launched the driver goes smoothly "through the stop" on "all out" and
smoothly back to the stop when he sees the glider rotate into full
climb. "Through the stop" means just that - not "on the end of throttle
travel". After that it depends on conditions. In calm that setting can
be kept most of the way up, but if there's a wind gradient the driver
will be backing off as the glider gets into progressively stronger wind.

The "stop" I mentioned is a spring loaded bar somewhere around (at a
guess) 75% power.

We use 3500 ft of cable and expect 1200 - 1500 ft from an ASK-21 flown
two-up in normal conditions - 6 to 12 kts headwind.

I'd endorse Bill's comment about hands-off trim. Our CFI regularly
demonstrates this in an ASK-21. He claps slowly from just after lift-off
to the top of the launch to show the student that he is flying hands off.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |