2 years ago our club (Soaring Club of Houston) invited a speaker from the Soaring Safety Foundation to speak at our club's annual safety meeting. Part of that presentation included a discussion on how to more effectively scrub excess altitude. The procedure is simple. Extend full airbrakes and then push the nose over to speed up. The drag is exponential to airspeed so a 15-20 knot increase in airspeed generates a tremendous sink rate. No need to slip.

A bit later that spring another SCOH pilot asked me to fly with him for a couple pattern tows so I had the opportunity to teach and video from the back seat. In the link that follows we're in a ASK-21 at 900 ft AGL on base and using the described procedure it only required speeding up to 80 knots to reach the approach end of the runway and use less than 1,000 ft to stop.

My take away from the lecture and this procedure is that it's always better to be on the high side.

https://www.youtube.com/watch?v=DE61...&feature=share