Roger Worden wrote:
I also understand that a properly balanced glider using a CG
hook for winch launch will tend to nose up initially, and will seek an
optimal climb angle naturally. Altering the climb angle with elevator will
necessarily result in a less-than-optimal altitude gain.

This applies to some gliders, e.g. ASK-21, G103, Puchacz, DG500, Pegase,
ASW19/20 and Discus to quote some I know to be benign on the winch, but
not to all gliders.

An ASK-21 trimmed to around 55 kts can be winched without moving the
stick. I haven't done it but our CFI uses this as a demo for students
who are wrecking the launch by misusing the stick. He claps from just
after lift off all the way to the top to prove he isn't flying the glider.

Ka-8s are known to need full forward stick through the ground run and
rotation due to their light weight the large moment arm between wing the
hook. I haven't winched one so can't comment further.

Libelles will snap-rotate as they lift off if you leave trim for
approach speed and leave the stick at that position - at least mine
will. There's nothing in the operator's manual about this. OTOH if I set
full forward trim and apply a little additional pressure past the full
forward trim position I get an nice lift off followed by a nice, slow
rotation into the full climb.

Gliders with heavily cranked sticks (Libelle again) may exaggerate this
effect because the stick will tend to flop backwards during the initial
burst of acceleration and its possible that having to hold the stick
forward may mitigate this tendency.

Get briefed about what the glider you're flying will do during the
launch BEFORE trying it. Snap rotation at lift-off is very dangerous -
the glider can stall and snap roll, which is why the BGA is currently
pushing slow rotation rates.

Remember to RELEASE IMMEDIATELY if a tip touches the ground during the
ground roll. The force vectors make your chances of getting the wing up
again rather remote and you won't have time to think about the
situation, so start the launch with your hand on the release. Mine stays
there all the way up. Remember that on a good winch, 0 to 50 kts is
about 5 seconds: you need to react rather than think if it goes wrong.


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