Nimbus 4 redline at 45000 and 55000 feet

Does anyone know the redline IAS for the Nimbus 4 at 45000 and 55000 feet? Does ballast make a difference?

Thanks

AH

On Wednesday, February 27, 2013 4:59:59 PM UTC-8, wrote:
Does anyone know the redline IAS for the Nimbus 4 at 45000 and 55000 feet? Does ballast make a difference?



Thanks



AH

Probably somewhere below stall speed!

On Wednesday, February 27, 2013 4:59:59 PM UTC-8, wrote:
Does anyone know the redline IAS for the Nimbus 4 at 45000 and 55000 feet? Does ballast make a difference?



Thanks



AH

What are you looking to do here? The IAS is always the IAS, but the Va is TAS. I assume you are trying to see how fast you can fly IAS for a TAS equal to Va.

If you can give me the Va number, I will assume standard temperature for FL450 and FL550, then using my handy E6B I can figure the IAS.

Mike

On Wednesday, February 27, 2013 5:59:59 PM UTC-7, wrote:
Does anyone know the redline IAS for the Nimbus 4 at 45000 and 55000 feet? Does ballast make a difference?



Thanks



AH

No. Design considerations are generally limited to operation in the first 6000m. There are some theories though.

Try searching rec.aviation.soaring via Google Groups on Technical Soaring EAS or TAS and/or IAS

Here's one such thread
http://tinyurl.com/cxn8odb

Frank Whiteley

When Klaus Ohlmann was in Colorado a year so so back he mentioned the N4D he flew to his distance record in 2003 had been "altered" by the factory to allow higher IAS at high altitudes. At the 2012 SSA convention in Reno, I asked Tilo Holighaus what Klaus was talking about.

His answer was they had taken another look at the N4D engineering and flight test data and decided the IAS altitude limitations could be eased. Apparently, Ohlmann's "alteration" was an edit to the Approved Flight Manual.

That said, there are airframe modifications which 'might' improve flutter resistance in the flight levels. Silicon oil filled hydraulic dampers installed as near as possible to the control surfaces are one possibility. Essentially, one pays the price of 'stiffer' controls in exchange for a greater flutter margin. Of course, that does nothing for airframe flutter which does not involve control surfaces.


On Wednesday, February 27, 2013 8:17:51 PM UTC-7, Frank Whiteley wrote:
On Wednesday, February 27, 2013 5:59:59 PM UTC-7, wrote:

Does anyone know the redline IAS for the Nimbus 4 at 45000 and 55000 feet? Does ballast make a difference?







Thanks







AH



No. Design considerations are generally limited to operation in the first 6000m. There are some theories though.



Try searching rec.aviation.soaring via Google Groups on Technical Soaring EAS or TAS and/or IAS



Here's one such thread

http://tinyurl.com/cxn8odb



Frank Whiteley

On Thursday, February 28, 2013 3:44:37 PM UTC-5, Bill D wrote:
When Klaus Ohlmann was in Colorado a year so so back he mentioned the N4D he flew to his distance record in 2003 had been "altered" by the factory to allow higher IAS at high altitudes. At the 2012 SSA convention in Reno, I asked Tilo Holighaus what Klaus was talking about.



His answer was they had taken another look at the N4D engineering and flight test data and decided the IAS altitude limitations could be eased. Apparently, Ohlmann's "alteration" was an edit to the Approved Flight Manual.



That said, there are airframe modifications which 'might' improve flutter resistance in the flight levels. Silicon oil filled hydraulic dampers installed as near as possible to the control surfaces are one possibility. Essentially, one pays the price of 'stiffer' controls in exchange for a greater flutter margin. Of course, that does nothing for airframe flutter which does not involve control surfaces.




There were some very good discussions on flutter margins, IAS, and altitude in Homebuilder's Hall articles from the 1970s or 1980s. Searching the SSA Archive will certainly turn them up. There are some commonly used rules of thumb along the lines of x% reduction per thousand feet, but they may not be good enough for the situations you're talking about (i.e. 2% per thousand feet at 50,000 feet is...)

P3

On 2/27/2013 4:59 PM, wrote:
Does anyone know the redline IAS for the Nimbus 4 at 45000 and 55000 feet? Does ballast make a difference?

Thanks

Maybe, maybe not. For such high altitudes you should start by talking
only to the factory. If they don't know, they will likely know who you
might talk to, but DON'T listen to people that tell you it's related to
TAS and they can figure it out! GO TO THE MANUFACTURER FIRST!

Flutter is difficult to predict at high altitudes, and it does not go by
IAS or even TAS over such a wide range. It's most unlikely Schmepp-Hirth
has tested it at such high altitudes. Don't mess with this - find out
from the people that built it.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

For comparison the Nimbus 2 redline reduction with altitude is
shown

http://www.gliding.co.uk/bgainfo/tec...ts/nimbus2a.pd
f

Gordon

How the heck does a Nimbus 2(a) data sheet help the OP who asked about a Nimbus 4?

On Thursday, February 28, 2013 10:56:23 AM UTC-7, Gordon Walker wrote:
For comparison the Nimbus 2 redline reduction with altitude is

shown



http://www.gliding.co.uk/bgainfo/tec...ts/nimbus2a.pd

f



Gordon

Fly w an instrument we give you the TAS (true airspeed) like LX9000

RC








"The trouble with weather forecasting is that it's right too often for us to
ignore it, and wrong too often for us to rely on it."



a écrit dans le message de groupe de discussion :
...

Does anyone know the redline IAS for the Nimbus 4 at 45000 and 55000 feet?
Does ballast make a difference?

Thanks

AH