Winch launch speed versus height gain

Well, yes, pitch strings 'work' but it's not really slick. They have to be
on the outside of the transparent canopy where you can see them. On most
gliders, that puts them too high on the side of the fuselage and further aft
than the ideal location making them sensitive to yaw. They really should be
at the maximum width or 'beltline' of the fuselage. Every time I've tried
them, the strings get caught under the canopy frame as you close up unless
someone stood by to ensure they didn't.

Pitch strings are fine for calibrating the best winch launch airspeeds or
illustrating AOA to a student but they're too crude for a permanent
installation IMHO.

Bill Daniels


"Mike Schumann" wrote in message
.. .
I can't imagine a more practical AOA indicator than pitch strings.

Mike Schumann

"Bill Daniels" bildan@comcast-dot-net wrote in message
...
Good answers all so far.

The correct answer is to fly the angle of attack corresponding to best
L/D. This can be determined with "pitch strings" attached to the sides of
the canopy. Once you know the corresponding airspeed, you can remove the
strings although many people find the strings useful enough to keep them.

Launching into a strong headwind, there is an advantage in slowing down a
bit but not so much that your AOA approaches that corresponding to Min
Sink. FWIW, the stall AOA is MUCH greater than even Min Sink.

We really need a practical AOA indicator.

Bill Daniels


"Neil" wrote in message
...
Ok, I could probably arrange with the winch driver to experiment, but is
there any definitive guidance on getting the greatest height off a winch
launch? (eg. Skylaunch).

i.e. if I'm "driven" at the higher end of the speed range acceptable to
my gliders placarding, will I get higher or lower than a lower speed
launch? I used to consider faster meant higher, but last weekend a most
experienced colleague said you'd end less high, as you spend less time
gaining height. I'm sure there's a set of graphs that would show a polar
curve type trade-off, but is there a simple way of looking at this?

Neil








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