Polar with spoilers extended?

Regarding being high on final, there is a place for both the full
spoiler/increased approach airspeed and the slipping technique. Just as
important as being proficient doing them is knowing how to choose the
most appropriate for the conditions. For example if the wind is strong,
the full spoiler/increased speed is generally safe because losing the
energy at the bottom of the maneuver should be no problem. If the wind
is zero or very light and/or there is a long line of gliders waiting to
launch (we land and depart at 4220 MSL on the same runway at Tehachapi)
and therefore the landing runway is shorter than normal, a slip might be
most appropriate since you get a high sink rate without adding excessive
energy to get rid of at the bottom.

As for doing a 360 in the pattern, you may need a plan B when the guys
behind you take the runway away from you.

Paul
ZZ








Dan G wrote:
On Oct 22, 5:58 pm, Eric Greenwell wrote:
I find it a very useful technique if I am high enough on final to use
it. Generally, I use it shortly after turning final as I realize I am
too high, even with full spoiler. That's when I have 500' agl or so,
which is plenty. Going from 50 knots to 70 knots (watch the flap setting
speed) doubles the rate of energy loss. When I slow down to 50 knots
again (still at full spoiler), my new "aim point" is much closer, and I
can reduce the spoilers to (ideally) about half.

All this is way outside my experience, and I'm not going to attempt it
myself (though I might nobble an instructor experienced at it).
However I still have a question: do you dive and then return to normal
approach speed before rounding out, or round out at the much faster
speed? If the latter, does not the extra float in ground effect negate
the losses from extra drag in the dive, especially with a slippery
glass ship versus a draggy wood and fabric glider (such as one a pilot
might train in)?


Dan