CM: Is that enough?
I’m almost afraid to post here for fear of being ridiculed by a few vociferous and largely nameless (in the latter respect, not you CM) experts who seem to delight in shooting down anyone with lesser knowledge or experience, but I’ll take my chance and pose what I believe is a reasonable question. Apologies in advance if I am typing out of turn, and shouldn’t even be visiting your ever so holy forum.
Leaving aside for a moment Lomcevak’s previous red herring which, in his defence, I recall as being the “guidelines” we worked to in my display flying days (long since passed), I have a question that someone with better maths skills than me could hopefully answer.
If we assume that the AAIB are correct in their determination that the aircraft reached a peak altitude of 2,600 (let’s call that AGL as the field is almost SL), and at the apex while inverted the IAS was noted by the AAIB as being 100kts, one might reasonably conclude that the aircraft had 2,100 feet within which to complete the manoeuvre. It might be argued by some that he actually had more than this, but unless it was another red herring Lomcevak also stated that “descent below the approved aerobatic height (500 ft in the case of this pilot, in the Hunter) to the approved fly by height is permitted once certain capture of the aerobatic display height.” (Assuming you lot have no objections therefore, I propose to use 2,100 feet for the purpose of my question).
With the limited information we have to go on at this point in time, would 2,100 feet have been sufficient in a Hunter – and without exceeding the aircraft limitations, or it leaving the envelope?
The approximate fuel load and weight of the aircraft has been determined, and the Permit to Fly flight test report will have recorded a recent un-accelerated 1G stall speed of the actual aircraft at a specified weight. From this it is easy to determine pretty accurate unaccelerated and accelerated stall speeds for any G value. (Pittsextra knows that). We also know that from the inverted the aircraft had to achieve a radius of 1,050 in order to meet the display floor, but we don’t know what thrust was used, or if indeed all of it was available. That stated, with the thrust normally available to the type, and forgetting the wind on the day, did the aircraft have sufficient space within which to meet the display floor limit of 500 feet, keep within the envelope, and was it possible to do so without exceeding any airframe limits for the configuration it was in?
I’m not entirely sure that it is possible to make a precise calculation (****, I'm not a military pilot), but surely we can narrow the field down a bit. For example, at 100kts (small radius) the manoeuvre would not have been possible – the required acceleration would have exceeded the flight envelope and the aircraft would have stalled. Similarly had excessive thrust been used (if it was even available), the radius would have exceeded the space available. Clearly there IS a balance of thrust versus pull required in order to achieve the smallest radius, but is it possible to calculate it – and align these figures to see if what was attempted was actually possible within a radius of 1,050 feet?
Ready for incoming!