dav wrote:

1.I have a guess at the question of airbrakes improving low speed
response-they simply deflect extra air around their sides, increasing
the airflow over ailerons and wing root.

Looking at top views of gliders, it appears the spoiler is always well
inboard of the aileron, so I don't see how significant air can be
deflected to them. With my ASW 20, the improvement occurred whether the
airbrakes were open 10 mm or 50 mm, so I think the improvement is caused
by spoiling lift rather than any deflected flow.

Tufting the wing between the spoilers and ailerons would allow a direct
check of the change in airflow. This could be done in a 20 mph wind, so
the glider would not even have to be moving.

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Eric Greenwell
Washington State
USA