Safety of winch launch vrs. aero tow?

About the Minden accident on 13 July 1999 to a Nimbus 4DM (LAX99MA251
http://www.ntsb.gov/publictn/2002/AAB0206.htm ).

Note that at the time the NTSB report was published there was discussion
about it on RAS. One of the things reported by posters with experience of
the Nimbus 3/4 models (I have none) was that the airbrakes have been known
to deploy uncommanded by the pilot. So the brakes may have deployed
themselves, and it is possible that this is what killed the pilots.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.


"Andreas Maurer" wrote in message
...


On 7 Nov 2003 23:40:26 -0800, (Slingsby)
wrote:

I still wonder if this killed the Nimbus4DM pilots in Reno.
Imagine looking at the ASI and not knowing if
you should be doing a spin recovery or a spiral recovery
(two very different things).


What really killed them were wings which, by design, are only good for
3.5 g (+50% if the glue holds) when you get into a stall/spin
situation.


The official conclusion sounds a little different:

The maximum manoeuvring load factor limits (in units of gravity or
g's) change with variations in glider speed and flap/airbrake
configuration. From a "flaps up" configuration at Va to the condition
of airbrakes and flaps extended at Vne, the maximum manoeuvring load
factor limits decrease from positive 5.3 to a positive 3.5.

In other words: If the pilots had not extended the airbrakes, the
Nimbus would not have disintegrated.

This is what NTSB thinks about what killed them:

The National Transportation Safety Board determines that the probable
cause of this accident was the pilot's excessive use of the elevator
control during recovery from an inadvertently entered spin and/or
spiral dive during which the glider exceeded the maximum permissible
speed, which resulted in the overload failure of the wings at loadings
beyond the structure's ultimate design loads.

Note the term "at loadings beyond the structure's ultimate design
loads".

Bye
Andreas