Originally Posted by
PDR1
The SHAR had an engine "dump valve" which diverted fuel flow to filling a sump as soon as it got weight on wheels* to ensure that when it touched the deck it stayed firmly there rather than being light or bouncing regardless of what the pilot did on the throttle. From the look of that video F35 doesn't have a similar system, which surprises me. Lots of things in that video look a bit odd. The initial hover is stable, and the reconfiguration for vertical descent seems to be to schedule (tailplane trim change) - thedescent rate is a bit higher than I'd expect, although the attitude is constant suggesting it was under control. The touchdown was definitely on the firm side, but seemingly not beyond the energy dissipation range of the undercarriage. But the thrust seems to remain at the descent setting (ie thrust = weight) allowing the aeroplane to bounce where I would have expected it to be closed to a safe value.
Shortly after the bounce there then appears to be a complete failure of the forward lift fan with ensuing pitch-down, wiping out the nosewheel etc. But the think that REALLY surprises me is that the engine seems to be still running at a high-ish thrust setting right up to the point where the pilot bangs out, suggesting that engine wasn't responding to the throttle commands until the ejection sequence cut the fuel flow.
The lift fan failure is obviously a concern and its cause will need to be established. But for me the bigger concern would be why the engine continued to deliver thrust for so long. I can't believe the pilot didn't try to shut it down, so that could imply uncommanded throttle operation. That's a bit scary.
PDR
* not sure it operated through the WoW switch - I think it was a completely separate system but I've forgotten the details as it's been 20 years since I last thought about it
conjecture, I know, but if the aircraft had already ‘landed’ (the bounce) perhaps the auto-eject system ‘thought’ that was it, and switched itself off? My limited knowledge of the system says that auto eject is almost instantaneous (quicker that the human brain) and he took a while to go. Main engine still going and drove the jet round on the grounded wing tip. Good presence of mind to wait. Reminds me of Bill Langworthys Jaguar episode. Disconnenected PFCU led to rapid rolling on take off. He said after, he waited till he saw brown for the second time.