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Shipboard Rolling Vertical Landing - The saviour of Dave-B?

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Shipboard Rolling Vertical Landing - The saviour of Dave-B?

Old 12th Sep 2008, 22:55
  #101 (permalink)  
Join Date: Jul 2008
Location: NSW
Age: 60
Posts: 150
Sorry to come so late to this thread and maybe it's already been raised.

Haven't seen it in my quick scan so I'll just make the point most vertical landings on carriers are made with the ship steaming into wind, so the wind over the deck is often quite high. This means, whilst the piloting technique used is definitely VL, the effect and benefit relative to the stationary planet is that of an RVL. IE any wing lift from wind is always aiding jet lift and therefore potentially increasing bring back loads.

This is particularly noticeable if you compare the Harrier I (less wing lift) approaches to the Harrier II approaches. The big throttle movement during the final transition from wing borne to jet borne flight in a Harrier I happened around 90 knots, whereas it was much later in the approach in a Harrier II. That's why the Harrier II youth used to enjoy the rudder inspection in their early approaches because they missed the throttle up with all the excitement of seeing the pitching/rolling boat!

To my mind, along with deck space issues, creeping and running VLs are avoided in both Harrier models because of weak brakes and slippery flightdecks. There is also the issue of manoeuvring within the 30-120 knot speed range with the Harrier's intake momentum drag stability issues. In a normal ship board VL, where you could be seeing indications of 60 or 70 knots anyway, those problems were avoided simply by keeping the vane straight and the AoA under control. If these problems are overcome then there should be no issue for the replacement jets doing CVLs and RVLs if it helps. It is slightly less flexible because more deck space will get taken up during the landing phase.

Remeber most innovation is brought on due cost. STOVL came about because countries couldn't afford conventional carriers. It could be said that because everybody is so rich now there is no reason why we shouldn't all go back to them. Having lived with both types of carrier though, I believe the desire to return to conventional carriers or "semi" conventional with catapult or arrester gear options really only complicates something that is very simple. And to my mind, innovation is moving forward whereas going back to something is not. STOVL, including CVL and RVL techniques, adds flexibility to the launch/recover options. Adding launch/recover machinery reduces flexibility by making the aircraft more dependant on mum. (IE if the machinery doesn't work the aircraft don't fly/become scrap metal)

Let new aircraft technology close the gap on the perceived (by some) performance benefits of conventional over STOVL aircraft and then move towards shorter runways on land as well.
DBTW is offline  
Old 13th Sep 2008, 03:55
  #102 (permalink)  
Join Date: Jan 2006
Location: Wiltshire
Age: 44
Posts: 34
What a load of rubbish

For reference ( of a sort ) we at BAe Dunsfold - no amount of money could seduce talented software guys to the northern slums of Wart On - had a whole, large building especially made housing over 200 people to solely write the control laws for the Eurofighter /Typhoon, they were particularly wary after the first Gripen's disaster ( how the Test pilot survived is still regarded a miracle ).
Where do get this from?
Without going into too much detail (off thread), DASA (as was) accomodated the FJT (Flight Controls Joint Team) out in Munich, there were engineers at Warton, involved in the design, but there certainly wasn't a purpose built building for 200 of them! A number of engineers employed by Warton did work in the software design team out in Germany, but there was only a few and they were not all from the SLUMS as you callously refer to the NW of England.
These engineers were working on Eurofighter flight control s/w a long time before the Grippen incidents and I can't recall anything changing for us as a result of the Grippen incidents.
Tightflester is offline  
Old 13th Sep 2008, 12:58
  #103 (permalink)  
Join Date: Jan 2004
Location: Far West Wessex
Posts: 2,510
True. Not a lot of point in planning a bolter if you've only got enough fuel to get to the impact point.
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Old 13th Sep 2008, 13:18
  #104 (permalink)  
Join Date: Dec 2006
Location: UK
Posts: 768
It's been a while since I was on the programme, and I don't know what the current figures are for the aircraft to go from landing mode to a 'bolter' mode - if that's what they are still looking at.

The distance available down the angle on CVF is about the same as a US CVN (by design), and at the forecast landing weights the F-35B gets off the deck fairly smartly and in a very short distance.

My view remains that to land an aircraft straight down the axis of a flight deck, relying on the (albeit very good) brakes to stop, is not the best way to go. In the final analysis, you are aiming a lot of energy straight where you don't really want it to end up. If you cain aim off, do so, and if you can also bolter, have it as another risk reducer.

Best regards as ever,

Engines is offline  
Old 13th Sep 2008, 18:08
  #105 (permalink)  
Join Date: Apr 2006
Location: Tullahoma TN
Posts: 482
Remeber most innovation is brought on due cost ...

I assume you mean "cost constraints."

Is that really true, in general?

It sounds like the kind of white lie one tells disgruntled subordinates.

For example, one might argue that the F35-B program itself is an unnecessary extravagance that US air power doesn't need, and that aircraft carriers of any sort should not be Britain's top military priority.

However, others here will reply that I am all wrong and that new STOVL fighter planes on new aircraft carriers are splendid innovations that the UK needs.

I suppose it all depends on who where one's paycheck comes from.
Modern Elmo is offline  
Old 13th Sep 2008, 19:06
  #106 (permalink)  
Join Date: Apr 2006
Location: Tullahoma TN
Posts: 482
The throttle will have to be brought to idle, otherwise you're p1ssing away your braking power.

That's a good point. It suggests the additional question, when does the human pilot start closing the throttle in this landing mode?

I suppose thrust vectoring might be used to hold the nose up after touchdown. Is that the case for SRVL landing?

These SRVL landings are planned to happen along the axial centerline of the aviation deck, and not on an angle deck, correct?

In general, is any sort of go-around attempt simply impossible because the F-35B will have insufficient kenetic energy to do so? Unless I've missed a post, the SRVL fellows posting here haven't firmly said yes or no on this point.
Modern Elmo is offline  
Old 13th Sep 2008, 21:49
  #107 (permalink)  
Join Date: Jul 2008
Location: NSW
Age: 60
Posts: 150
I think the main point about any landing referred to as "vertical" does not have a bolter requirement once you are on the deck. Leaving power up after landing puts you in a dangerous position in terms of contolling a bounce and stopping. As soon as you are down the power comes off and the aircraft is stopped.

The conventional carrier landing technique of powering up on touch down in case you miss a wire does not apply because a landing where the aircraft is mostly jet borne, as distinct to wing borne, needs to have the power completely off on touch down.

Having said that, if you are doing a true VL relative to the deck, I have seen pilots start the descent, not like the picture, re-apply power and pop the aeroplane back up in the hover to reposition. Assuming the SRVL technique being advocated is similar to the Harrier technique, this kind of action will be a little harder to do in a running VL as I think we are assuming the aircraft will be performance limited and using the technique to bring back loads in excess of the normal hover weight. Even so, whilst partially wing borne and partially jet borne in the approach, a pilot using an SRVL technique should be able to initiate a successful go around until just before touchdown.

Last edited by DBTW; 14th Sep 2008 at 01:15.
DBTW is offline  
Old 13th Sep 2008, 21:52
  #108 (permalink)  
Join Date: Jul 2008
Location: NSW
Age: 60
Posts: 150
Modern elmo. Good point about who pays.
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