Vaughn Simon wrote:
"Eric Greenwell" wrote in message
news:GIg0h.12159$iM2.2023@trndny08...
To recap, one of the SparrowHawks built for Mississippi State University broke
up in flight Oct 18. The pilot parachuted safely.

Any word on why the pilot elected to "get out and walk" rather than ride
the BRS down? I wouldn't be the one to second guess his decision, but it
apparently came near to turning out very badly.

The breakup of the glider was so forceful, it threw him out of the
glider with the remnants of the seat attached to him by the lap belt.
The lap belts are connected to the seat, rather than the fuselage, as in
many (most?) gliders. The BRS was apparently activated when the
structure with the activation handle tore from the main fuselage.

The pilot's parachute did not open properly at first because it was
hindered by a small piece of the canopy frame that was still connected
to part of the seat pan by the lanyard that holds the canopy in the open
position on the ground. Nobody can believe the lanyard (and the little
screws that hold it) survived the breakup, but the fuselage attachment
point will be definitely be changed!

Greg said calculating the forces on the components during a catastrophic
failure like this is difficult, because you don't really know what is
deforming, how it's deforming, and how fast it is deforming, and rapid
deformation changes the strength values you have to use in the
calculations. He says they will revisit the problem and find ways to
strengthen the safety harness connection to the glider, but can't
guarantee the changes will survive such a high speed breakup (almost 50
knots over 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