500 km Triangle at 306 km/hr in Argentina

Marc Ramsey wrote:
Marc Ramsey wrote:
Soarin Again wrote:
At 05:42 23 December 2006, Js wrote:
306 km/hr = 190 mph = 165 knots

That is an amazing feat!

Yes, it is.
Anyone trying to beat that record should be certain
their parachute is
in good shape, as the number of wings will likely total
zero.
Jim

Does anyone know if his Nimbus 4DM has had special
modifications to increase the vne at altitude, or does
he just not care about operating limitations?

306 km/hr true airspeed is 200 to 220 km/hr IAS at the 20000+ foot
altitudes used for these wave flights. Some gliders do require a
reduction in Vne at higher altitudes, but it isn't necessarily the case
that the limitation was exceeded.

If the 4DM follows the protocol used by the Duo (for which I have a
manual), Vne is IAS up to approximately 2500M altitude, then the
equivalent TAS from there up. If Vne for the 4DM is 275 km/hr, the TAS
limitation would be around 310 km/hr.

The Vne for the Nimbus 4DM is 285km/h (154 kt). Flutter speeds do not
follow TAS, but actually follow approximately 3/4 the way between IAS
and TAS. So it is possible to fly safely past 300km/h at altitude.

I do remember reading something a little while back on the SH website
about them having modifed a Nimbus 4 for high altitude record flights
in Argentina. If I recall correctly they did modifications (probably
some mass balancing) to counter the onset of flutter as a result of
high TAS at altitude.

Markus

Markus schreef:

I do remember reading something a little while back on the SH website
about them having modifed a Nimbus 4 for high altitude record flights
in Argentina. If I recall correctly they did modifications (probably
some mass balancing) to counter the onset of flutter as a result of
high TAS at altitude.

Markus

Yeah; it's over he
http://www.schempp-hirth.com/index.p...r]=1&tx_ttnews[tt_news]=48&tx_ttnews[backPid]=87&cHash=3f1ff7d791

"The maximum speed at high altitudes heights could be significantly
increased through modification of the Nimbus-4D/DM. Fortunately these
advantages could be realised this year with record flights in the waves
of the Andes in South America"

I'm curious whether they only placed lead, or the complete wing and
tail is redesigned.

Hopefully everybody going after such a record has had all the right
mods done. There have been a couple of broken spars in the Sierra wave,
and it would be great if that trend wasn't continued.
Jim