V Speeds for AH planes - IAS or TAS?

[beet1e]

My favourite fighter planes in Aces High are the P51D and the F4U-1D. Flying the P51D tonight, I was able to use its speed to dive away from trouble or to catch up to a con. I always understood the VNE (Velocity Never to Exceed) of the P51D to be about 500mph.

Now I’m no test pilot, but I do have about 900 hours P1 time in a TB10 (pictured). And I always understood that any speed limitations as denoted by coloured arcs or lines (or the Pilot's Operating Handbook) related to Indicated airspeed, and not True airspeed, which is why colour coding of the airspeed indicator is used in planes these days. But...

...tonight in my P51D, I was at about 22K, and began a dive on a bogie (another P51) and my plane started to buffet (control flutter?) at only 400mph IAS. Admittedly, that trued out at over 500mph TAS. (I like the way AH puts the TAS as a red marker on the ASI.) But I am still surprised to have got buffeting and loss of control authority at 400 IAS. Can someone confirm that this is correct, and also explain whether it’s True or Indicated airspeed that counts in assessing stress factors.

Hope you like this pic of my Tobago. I once flew her over the French Alps. At around 10,000ft on a warm day, the IAS with Max available power (19”/2400rpm) was 115 knots, with an IAS of 95 knots

[Daff]

Buffeting (compression) is based on  Mach no., not IAS.

Daff

[beet1e]

Thanks Daff. I thought you might say something like that. But I was thinking this morning, the "thinness" of the rarefied air at 22K must have something to do with the stress on the airframe. Imagine the P51 had a rocket motor (like some of the other AH planes LOL) and could travel in space where there is no air at all. It could travel at any speed without any stress to the airframe and no buffet. OK, an extreme example perhaps, but you can see my extrapolation here.