Speeds such as VD are specified as Equivalent AirSpeeds in the standards - hence altitude should not be an issue. The exception is when mach number is a limit - MD rather than VD.
Trying to keep it simple. MD is 0.80. VD is 505 IAS at race altitude and up to a certain altitude that I forget.
Was this aircraft actually tested to a declared VD?
The teams have competent structural engineers from industry and the owners listen to them. If they required a test, they would have gotten it. They would have corrected to VEAS where they could, but doubt they would have done it at 3-5 g's. There's a perception that the airplanes are being pushed beyond the original design limits, but the Mustang guys honor the 505 IAS limit, and frankly they're having a hard time getting there. Though there might be some truth in that since the 505 IAS limit wasn't established at 3-5 g to begin with.
As a matter of interest, does anyone know to what extent these aircraft are tested against standards? As an experimental aircraft they are obviously not expected to meet all standards (eg FAR23), but is there a set of minimums that are applied?
They're licensed in the eperimental catagory, maybe experimental/exhibition. Don't think they're restricted. Basically means you can do what you want as long as the hardware is airworthy and is signed off by the mechanics. The teams I contacted about mods were very concerned about safety, and we convinced ourselves we had the same level of concern when it came to modifying the airplane, i.e., I was originally concerned they might slap something on and go fly at Reno, and they assured me they wouldn't. In this sense, think the FAA is/was comfortable with owner's getting with the profesionals for any mod program.