To recap, one of the SparrowHawks built for Mississippi State University
broke up in flight Oct 18. The pilot parachuted safely.

I just finished talking to Greg Cole, designer of the SparrowHawk. The
program manager from MSU visited him Monday to discuss the data from the
flight and pictures of the pieces. The short story is the pilot
inadvertently exceeded Vne while performing a rolling maneuver as part
of the test program, and the glider broke apart at 171 knots!

The speed and most of other data used in the analysis came from the data
logging system carried in the glider. A helicopter making a video
recording was following it at the time it broke up. The calculated
flutter speed, using measurements from ground-based stiffness and
frequency tests of a SparrowHawk (not the MSU glider) is 170 knots. For
this reason, and the speed of the breakup, Greg thinks it was almost
certainly flutter that caused it.

It's quite remarkable it lasted to the 171 knot speed, given it's 123
knot Vne. The demonstrated flight speed for certified gliders is Vne +
10%, which would be only 135 knots for a 123 knot Vne.

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org