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