Test Landing Video of F-35B
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Well it's a nice video, and if as I suspect G.T. is flying the thing, I'm not surprised it was a good landing.
Speaking of which, beside it being great to have the same number of landings as take-offs, what's the point ?
Loading, conditions, aircraft status compared to proposed production job...
Speaking of which, beside it being great to have the same number of landings as take-offs, what's the point ?
Loading, conditions, aircraft status compared to proposed production job...
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Do a Hover - it avoids G
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The hover attitude (not angle of attack) is determined by the gear. As it has a tricycle gear the nose wheel must not hit first or even with the mains. So the hover attitude will be very similar to that used on a forward speed landing.
The angle of attack in the hover that necessarily results from the attitude needed will depend on the wind. In zero wind during the descent phase this could be as much as 90deg less any negative value cause by induced downflow from the lifting system.
The hover attitude (not angle of attack) is determined by the gear. As it has a tricycle gear the nose wheel must not hit first or even with the mains. So the hover attitude will be very similar to that used on a forward speed landing.
The angle of attack in the hover that necessarily results from the attitude needed will depend on the wind. In zero wind during the descent phase this could be as much as 90deg less any negative value cause by induced downflow from the lifting system.
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BEagle.
After your mention on another thread of a long cancelled British prototype, I can't help thinking that for the first 30 seconds of this video, the aircraft could almost have twin booms and be of British design.
From various angles, the JSF and P1216 don't look too different (OK, with a bit of imagination then).
After your mention on another thread of a long cancelled British prototype, I can't help thinking that for the first 30 seconds of this video, the aircraft could almost have twin booms and be of British design.
From various angles, the JSF and P1216 don't look too different (OK, with a bit of imagination then).
I have to say that having been impressed at the smoothness whilst watching the VAAC Harrier landing using the JSF software, that landing was rough in comparison.
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I'm not sure if you're referring to the lift intake or the door above it; am I the only one who cringes at the idea of the thing with AFT HINGES, I bet there quite a few klaxons & lights to warn of overspeeding that !
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Just to clarify, this video of F-35B is of its slowest landing to-date. 40kts I believe, and one of the last 'gates' it makes before shortly doing its first hover. So, any talk of "high AoA in the hover" does not apply here.
The high apparent AoA is controlled/optimised to maximise the wing lift generated, offsetting the amount of delta needed to keep it up by the engine (engine life etc) and this is part of the design for slow speed flight. During the later part of the video showing the aircraft from the rear, I would imagine that G.T was looking at small directional inputs (bank controls 'line' blah, blah) at that speed as part of the test.
Great achievement in aviation by any standard, regardless of those who pooh-pooh STOVL F-35 as a required concept.
The high apparent AoA is controlled/optimised to maximise the wing lift generated, offsetting the amount of delta needed to keep it up by the engine (engine life etc) and this is part of the design for slow speed flight. During the later part of the video showing the aircraft from the rear, I would imagine that G.T was looking at small directional inputs (bank controls 'line' blah, blah) at that speed as part of the test.
Great achievement in aviation by any standard, regardless of those who pooh-pooh STOVL F-35 as a required concept.
Do a Hover - it avoids G
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Vec
There are several reasons why the hover would be high (compared to early 1127/Kestrel/ and typical Harrier ones).
Going back to the early 60s escape following an engine failure in the hover was problematical given the limited performance of non-rocket seats. So at a lower hover height it was hoped that you could survive a heavy landing if you stayed in the aircraft. Remember thrust does not decay to zero instantly in even the most dramatic types of engine failure. That was borne out by the first guy to have an engine failure in the hover a Marine who hit hard and flat and bent the wings up but was OK.
Again at that time handling was demanding and the further you were from the ground the weaker were the visual cues and the harder it was to keep control.
These days escape should not be a problem and indeed we are probably back to the higher the better especially with a device that is held up by a pair of props front and rear which could fail independently.
In any test/development flight you get the best data so far as hovering efficiency numbers are concerned by being well out of ground effect. I dont know where ground effect starts on the F35B but it is a 40000lb class vehicle so it shifts a lot of air downwards.
As to quality of touchdown a good vertical landing on the hard in my view is one that restricts time in ground effect and gives about 4ft/sec at impact. This looks AWFUL to an observer because the only velocity he notices is the vertical one. When somebody plants a conventional jet at 10 12 ft/sec we hardly notice this because of the 140 150 kts horizontal at the same time that is rather more obvious.
So all in all I would expect GT to have been at the briefed height plus or minus not much.
JF
There are several reasons why the hover would be high (compared to early 1127/Kestrel/ and typical Harrier ones).
Going back to the early 60s escape following an engine failure in the hover was problematical given the limited performance of non-rocket seats. So at a lower hover height it was hoped that you could survive a heavy landing if you stayed in the aircraft. Remember thrust does not decay to zero instantly in even the most dramatic types of engine failure. That was borne out by the first guy to have an engine failure in the hover a Marine who hit hard and flat and bent the wings up but was OK.
Again at that time handling was demanding and the further you were from the ground the weaker were the visual cues and the harder it was to keep control.
These days escape should not be a problem and indeed we are probably back to the higher the better especially with a device that is held up by a pair of props front and rear which could fail independently.
In any test/development flight you get the best data so far as hovering efficiency numbers are concerned by being well out of ground effect. I dont know where ground effect starts on the F35B but it is a 40000lb class vehicle so it shifts a lot of air downwards.
As to quality of touchdown a good vertical landing on the hard in my view is one that restricts time in ground effect and gives about 4ft/sec at impact. This looks AWFUL to an observer because the only velocity he notices is the vertical one. When somebody plants a conventional jet at 10 12 ft/sec we hardly notice this because of the 140 150 kts horizontal at the same time that is rather more obvious.
So all in all I would expect GT to have been at the briefed height plus or minus not much.
JF
