Originally Posted by Reheat On
If you examine this video and do a fag packet calculation from second 7 to second 11, concluding he travelled about 400 yards, it appears entry speed was the order of 180kt - that to me appears slow, and confirmed the sucking in of air by pilot-spectators with me & off the cuff comments on entry that "this might be tight"
As someone else said, good post, but let's just look at that fag packet again.
If the estimated distance is instead 500 yards the speed is 225 knots; 555 : 250
There will probably be careful examination of such details to try to derive more precision, but even so there will be margins for measurement tolerances.