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

Stefan wrote:
Greg Arnold schrieb:

When you are cruising at 20,000' to 30,000', doesn't the effect of
altitude cause IAS to be substantially less than ground speed?

Vne goes with TAS, not IAS. But then, as it most probably was a wave
flight, there most probably was a wind.

Yes, but in a closed course, the wind is a net loss, not a benefit.

Doug Haluza wrote:
Stefan wrote:

Greg Arnold schrieb:


When you are cruising at 20,000' to 30,000', doesn't the effect of
altitude cause IAS to be substantially less than ground speed?

Vne goes with TAS, not IAS. But then, as it most probably was a wave
flight, there most probably was a wind.


Yes, but in a closed course, the wind is a net loss, not a benefit.

That all depends on the profile of the wind. Different speed and direction at
different altitudes can no doubt be a benefit.

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.

I find these sorts of discussions amusing. Do F1 drivers religiously
follow redline engine speeds or anticipated braking limits for
conditions when they're out to beat the next guy?
Breaking records in aircraft is not analogous to driving the family SUV
to the mall, or the 1-26 around a silver distance triangle. Speed
limits and safe and reasonable don't apply. If it wasn't pushing the
envelope, we'd all be doing it.
My $ 0.02.


Shawn

Shawn schreef:

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.

I find these sorts of discussions amusing. Do F1 drivers religiously
follow redline engine speeds or anticipated braking limits for
conditions when they're out to beat the next guy?
Breaking records in aircraft is not analogous to driving the family SUV
to the mall, or the 1-26 around a silver distance triangle. Speed
limits and safe and reasonable don't apply. If it wasn't pushing the
envelope, we'd all be doing it.
My $ 0.02.


Shawn

When not flying in an airworthiness glider you're simply not allowed to
fly at all, so no records either. That does give Americans (of which
most have an experimental registrated glider) in fact an unfair
advantage, but up to now no one cared. Maybe that's gonna change...

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

On 23 Dec 2006 06:54:01 GMT, Soarin Again
wrote:


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?


Exceeding the standard Vne was not necesary for this record flight.


I don't have the POH of the Nimbus at hand, but the DG-1000 numbers
are this:

http://dg-flugzeugbau.de/Handbuecher/flugh-1000s-d.pdf page 2.3

Vne (IAS) at sea level: 270 kp/h
Vne (IAS) at 8.000m: 205 kp/h IAS = 317 kp/h TAS

TAS calculator he http://www.flightplan.za.net/trueAirspeed.php

Given the 15 kp/h higher Vne of the Numbus 4D and a similar
Vne/altutude calculation scheme I expect a maximum legal TAS of about
325 kp/h at 8.000 m.





Bye
Andreas

Shawn wrote:
Marc Ramsey wrote:

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.

I find these sorts of discussions amusing. Do F1 drivers religiously
follow redline engine speeds or anticipated braking limits for
conditions when they're out to beat the next guy?
Breaking records in aircraft is not analogous to driving the family SUV
to the mall, or the 1-26 around a silver distance triangle. Speed
limits and safe and reasonable don't apply. If it wasn't pushing the
envelope, we'd all be doing it.

And that's why I think these discussions are interesting instead of
amusing. What risks are they taking, and how did they determine these
risks? Klaus does not seem a like a crazy man, so I suspect his risk
analysis would be very enlightening. And now we know it's a modified
Nimbus, so perhaps he is not taking any extra risk at all - even more
interesting! I hope we hear more about the modifications and how they
tested their effect.

--
Eric Greenwell - Washington State, USA
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