Busterbucani,
I appreciate your reply and stand guilty as charged of thread creep! However, if there are to be on-going discussions of accelerated stalling then a knowledge of the high altitude aspects, even if not relevant here, is a useful education. My use of the phrase 'not as simple as you implied' related to the complexities of stalling and not this accident. I would like to respond to a few of your points.
When converting to a swept wing jet a pilot will not practise taking it to the point of departure unless that is a cleared manoeuvre that is approved in the Flight Manual. I do not have a Gnat Manual to hand so cannot comment on that type but, for example, the Hunter was not cleared for intentional departures in service (although it was when specially instrumented in the flight test world).
Many (most?) display accidents, in piston engined aircraft, straight wing and swept wing jets, occur because there is insufficient height to execute a safe recovery from the aircraft's pitch and roll attitude. For example, being too low at the top of a loop, rolling with too low a nose attitude such that the nose drops to an irrecoverable dive angle.
The P-51 is one aircraft type that does have accelerated stall characteristics that can result in an inadvertent departure during a display. It has an essentially laminar flow wing which results in a very rapid right roll at the point of stall with no prior buffet (although a P-51C that I have flown did have a very narrow buffet margin when compared to the Ds that I have flown); in essence, it has no stall warning. The other type that I have displayed that has the same problem (albeit with not quite such a high roll rate at departure) is the Harvard/SNJ/T6. Most other aircraft, and especially swept wing ones including the Gnat, have some buffet margin to warn of the accelerated stall and in many aircraft the accelerated stall characteristics are actually quite benign.
The swept wing jets that I have departed (Hunter, Alpha Jet, F-16, F-18, Hawk intentionally, Tornado unintentionally!) invariably have a very rapid yaw off at the point of departure, often simultaneously with a roll off and pitch up. In the accident video it appears to me that the final motion that can be seen is a left roll from approximately 90 deg to around 120 - 130 deg bank angle with a simultaneous nose up pitch rate that was present before the roll occurred. I cannot see any noticeable yaw but that does not mean that there isn't a yaw rate developing. Draw your own conclusions, please.
Until the video is analysed fully in order to ascertain airspeed and pitch rate no-one can estimate the normal acceleration that the aircraft had just prior to impact. From memory I believe that the g limit in the Gnat was +7g (although I may be wrong) and the display sequence notes on the team's website mention 6g turns. Therefore, I think that any comments about +8g are not appropriate.
Unfortunately, there is one comment that I will take you to task about, your comment "I mourn the lost aircraft as I mourn its pilot". I find that extremely distasteful and disrespectful to his wife, family and friends. I fail to see how any sentient being could feel that way.
Last edited by LOMCEVAK; 5th Aug 2015 at 16:01.