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-   -   Shipboard Rolling Vertical Landing - The saviour of Dave-B? (https://www.pprune.org/military-aviation/340021-shipboard-rolling-vertical-landing-saviour-dave-b.html)

You Sir, Name! 21st Aug 2008 18:14

Shipboard Rolling Vertical Landing - The saviour of Dave-B?
 
UK to extend rolling carrier landing research for JSF


The UK Ministry of Defence is continuing research to refine a hybrid shipboard rolling vertical landing (SRVL) technique, potentially to be employed as the primary recovery mode for Lockheed Martin F-35B Joint Strike Fighters operating from the Royal Navy's two Future Aircraft Carriers (CVF).
A programme of MoD-sponsored research work, including technical advice from the Defence Science and Technology Laboratory (Dstl), has already concluded that SRVL would offer a significant increase to the F-35B's payload "bring back", without any fundamental platform or safety issues. However, further investigations are planned to address a range of optimisation and integration issues, says Martin Rosa, JSF technical co-ordinator in the Dstl's air and weapon systems department.

http://www.flightglobal.com/assets/g...x?ItemID=23837 © USAF

An SRVL involves a short take-off and vertical landing aircraft performing a "running landing" on to the carrier flightdeck, using air speed to provide wingborne lift to complement engine thrust. The touchdown position on an axial flightdeck is similar to that of a conventional carrier - about 45m (150ft) from the stern, but no arrestor gear is required, as the aircraft uses its brakes to come to a stop within a distance of 90-150m. The technique could allow an F-35B to recover with an extra 907kg (2,000lb) of weapons and fuel, or reduce propulsion system stress and increase engine life.
The Dstl began work to examine the feasibility of employing the SRVL manoeuvre in the late 1990s. Following a series of simulation-based studies, the MoD's investment approvals board in July 2006 endorsed the requirement as part of its F-35B-based Joint Combat Aircraft programme.
Speaking at the Royal Aeronautical Society's International Powered Lift conference in London in July, Rosa said SRVL studies have shown that "a way forward exists to achieving operationally useful increases in bring-back, compared to a vertical landing, on board CVF with an appropriate level of safety". But "uncertainties remain in terms of the scope of an operational clearance and the potential impact on the sortie generation rate for CVF".
Qinetiq used its VAAC Harrier testbed to perform representative land-based flight trials and a ship-based SRVL demonstration aboard the French navy's aircraft carrier Charles de Gaulle last year.
Rosa said past work has also identified a promising visual landing aids (VLA) concept optimised for SRVL and stabilised against deck motion. "We will continue to mature the SRVL-optimised VLA arrangements, look at the possible 'tuning' of the JSF flight-control laws, and further study the effect of SRVL on the CVF sortie generation rate," he said. The capability's full scope will be confirmed after flight trials from the 65,000t vessels, which are due to enter service in 2014 and 2016, respectively.
Other forthcoming work includes optimisation of the approach profile, agreement on the optimal post-touchdown technique, and mitigation for failure cases, such as a burst tyre on touchdown.

Jetex Jim 21st Aug 2008 18:28

Very interesting.

Rosa said past work has also identified a promising visual landing aids (VLA) concept optimised for SRVL and stabilised against deck motion. "We will continue to mature the SRVL-optimised VLA arrangements, look at the possible 'tuning' of the JSF flight-control laws, and further study the effect of SRVL on the CVF sortie generation rate," he said. The capability's full scope will be confirmed after flight trials from the 65,000t vessels, which are due to enter service in 2014 and 2016, respectively.
The investigation of visual landing aids, and tweaking with control laws suggests that SRVL may not be as straight forward has some have indicated.

Too bad the old, 'it's better to stop and the land, than land and then stop', idea seems to be, being eroded.

Engines 21st Aug 2008 20:50

Good to see Martin Rosa getting some visibility - I've known him for some years - he really knows his STOVL stuff, and has made major contributions to the UK's JSF effort.

JJ - looking at VLAs and possible flight control law optimization is EXACTLY what the team need to be doing to get the best out of SRVLs. If they go down this route (and I'm a proponent of it) a good VLA is a must for safety and best sortie rate. The flight control 'tuning' being described could well be applied to other JSF scenarios - it's required to do land based RVLs for the USMC as part of its basic requirement set.

The old 'it's better to stop and then land, than land and then stop' is still good, but how about 'It's better to slow down to a near crawl then land, than land at 140 knots and then hook a wire to come to a halt'? Not as snappy, but worth thinking about.

Modern Elmo 22nd Aug 2008 01:04

The old 'it's better to stop and then land, than land and then stop' is still good, but how about 'It's better to slow down to a near crawl then land, than land at 140 knots and then hook a wire to come to a halt'? Not as snappy, but worth thinking about.

How about, "It's better to be able to go around and try again, if you bolter the landing attempt?"

How about, "Shipboard Rolling Vertical Landing - The Harrier old boys club's false Messiah?" ... as if the STOVL F-35 needs to be saved by some Brits.

Modern Elmo 22nd Aug 2008 01:10

Rosa said past work has also identified a promising visual landing aids (VLA) concept optimised for SRVL and stabilised against deck motion. "We will continue to mature the SRVL-optimised VLA arrangements, look at the possible 'tuning' of the JSF flight-control laws, and further study the effect of SRVL on the CVF sortie generation rate," he said.

Yes, very well, how about an automated landing system, stabilised against deck motion, such as later model F-18's already have?

Jetex Jim 22nd Aug 2008 02:10

Engines, I suppose it depends what you mean by a near crawl.

The touchdown position on an axial flightdeck is similar to that of a conventional carrier - about 45m (150ft) from the stern, but no arrestor gear is required, as the aircraft uses its brakes to come to a stop within a distance of 90-150m.
They could always give it a hook, I suppose...





.

Modern Elmo 22nd Aug 2008 19:11

Definitely the next move for the RN's Rolling Stop Program.

"Can't you retrofit it with a sort of, er, lightweight barrier engagement device?"
Air Force Fighters & Tailhooks

http://www.aerospaceweb.org/question...tailhook-2.jpg
F-16 being decelerated by a crash barrier cable

Aerospaceweb.org | Ask Us - Air Force Fighters & Tailhooks

Engines 24th Aug 2008 08:46

Modern Elmo, JJ,

The team have looked at getting a hook on the STOVL (wasn't in response to SRVLs) and it's quite a job. The F-35A has one for land use, the F-35C has a monster one for shipboard use, but the B doesn't have the structure under the aft fuse to fit one, as it has to be left clear for the aft nozzle to swivel down.

All USN deck landing systems are stabilized against ship motion, and yes they do have an automated capability. I understand that they rarely use the full 'hands off' automated capability, but they do use the system extensively at night to aid stabilizing the aircraft on the glideslope. The work being done right now, I believe, is to assess SRVL workload against various scenarios and decide whether a full autoland capability is required.

ME - I can't support the view that SRVLs are a 'false messiah', nor do I think the Brits are trying to 'save' the F-35. SRVLs are most probably being looked at because the Brits want the aircraft to do more than the agreed specification asks for. I do agree, though, that we should aim to give SRVLs a bolter capability.

Schiller 24th Aug 2008 09:25

"Better to stop and then land..." sez who.
Better to have the best performing aircraft you can find and then find out how to land it. That´s what professional pilots are for.

dirty_bugger 24th Aug 2008 11:53


That´s what professional pilots are for.
...quite right! why don't we get rid of the flight control system and really make professional pilots earn their flying pay instead of trying to make flying safer...TALLY HO CHAPS....

Jetex Jim 24th Aug 2008 14:59

Engines:

SRVLs are most probably being looked at because the Brits want the aircraft to do more than the agreed specification asks for.
This wouldn't because what is 'agreed' now is different to what was originally expected, would it?

Here's what Dr Kopp had to say on the subject in May, this year.

The saga of the weight reduction effort is a good example, as early in the SDD it was established that the airframe with systems installed was too heavy to perform, a critical definicency for the STOVL variant. This was followed by the SWAT (STOVL Weight Attack Team) effort intended to drive the weight of the design back to an acceptable number. The SWAT effort was followed by a major public relations campaign declaring publicly that the weight problem had been beaten. When the published target weight data for the JSF variants is tracked over time, it is clear that empty weight remains a major design problem. Between 2002 and 2006, the weight of the CV variant grew by 6.7%, the STOVL variant by 8.2% and the CTOL variant by 9.6%.

A look at:
Assessing Progress on the Joint Strike Fighter Program
shows how the baseline weapons fit has been steadily whittled away since 2001.

LowObservable 25th Aug 2008 14:03

On the Future Carrier thread, a poster who seems to know where his towel is suggests that the need for SRVL is driven by the definition of a "hot day", with the RN looking at hot/low pressure days that are more severe than Marine standard days... of course the Marines are stuffed anyway, since their decks aren't big enough to begin with.

Schiller 25th Aug 2008 14:59

It´s not a question of safety. I don´t know that STOVL is any safer than cats and traps. Its just that any self repecting aviator would like to go to war with the best performing aircraft he can get. If that means he has more of a job landing it - well, so be it. He has to learn how to do that.

Modern Elmo 25th Aug 2008 18:40

Its just that any self repecting aviator would like to go to war with the best performing aircraft he can get.

Please define "best performing aircraft" for aircraft carrier operations.

Modern Elmo 25th Aug 2008 18:51

Here's what Dr Kopp had to say on the subject in May, this year.

The good Dr. Kopp. How are you doing there, Charley?

What do you suggest for the Fleet Air Arm? A well-chosen mix of Sukhois and F-111's?

LowObservable 25th Aug 2008 20:37

Modern E - argumentum ad hominem, dude. You may have your opinions about Dr Kopp (who doesn't?) but the F-35's weight history is relevant to this discussion.

dirty_bugger 25th Aug 2008 21:30

schiller - I agree that any nation should send their men/women to war in the best kit available (please note that it is nothing to do with professional aviator bollox, just best kit for purpose). however, modern procurement policy is not about best kit - it is about meeting defence targets in something that is affordable. If you want the best kit ....give us the cash! if you want the best value for money then F35 will give it to you. If you want to pmp money into british economy give it to BAES for Typhoon.

compromise baby.......

Jetex Jim 26th Aug 2008 03:30

dirty b

if you want the best value for money then F35 will give it to you. If you want to pmp money into british economy give it to BAES for Typhoon.
Interesting, and that latter assertion is not something one could make regarding Dave-B, you believe?

From
Navy argues against Marine variant of JSF - Marine Corps News, news from Iraq - Marine Corps Times

British support for the F-35B is seen by many observers as a key element in the survival of the variant in last year’s Quadrennial Defense Review (QDR). Although the QDR was completed over a year ago, the British carrier program remains a major ingredient in the STOVL program.
A British government official said Pentagon officials “periodically seek updates from the British government on the status of the carrier program — a move that some have suggested has less to do with Britain’s interest in building the ships than whether London is wavering on the raison d’être for the JSF STOVL program.”
A rather interesting way to describe it, don't you think?

Which is to say, without Dave-B BAE wouldn't be participating in the JSF manufacturing club. -- Too bad, I think, that the price of membership includes two dedicated STOVL 65,000 ton carriers. (BTW the nuclear CdG weighs in at a mere 42,000 tons)

Question_Answer 26th Aug 2008 19:27

IIRC The VAAC Harrier successfully performed an automated VL a couple of years ago. Aren't many UAV now doing autolanding? So surely not too tricky to achieve autoland SRVL with F-35. Regarding slowing down post SRVL landing, would that be entirely down to the performance of the braking system, i.e. no reverse thrust vector? 90-150m, sounds very tight - how far does a fully laden truck (40T) take to stop on a wet road at say 50mph?

Irrespective of whatever funding cuts may be round the corner, BAES will be getting money, whether its through F-35, CVF, Typhoon, Nimrod, Astute, UCAV...............but then we do want to retain an organic defence/aerospace manufacturing capability dont we?

Double Zero 26th Aug 2008 19:30

I notice one particularly experienced VSTOL Test Pilot is being very restrained on this subject - possibly as a lot of b----cks is being spoken !

Yes, stop then land, or nearly so; I don't reckon an approach speed of 140 kts sounds like a ' near crawl ', more like a 'near F-4' !

In WW2 the F4U Corsair was reckoned a good thing once airborne, but it took Eric Brown - with exceptional skills - to convince the USMC to use it aboard ship.

When I saw a recent claim that only 129 ( I find that figure very dubious ) Corsairs were lost in combat, and of course claimed about 4,000 kills, I would have laughed if the subject was not so sad; i.e, how about landing / training accidents - same goes may I suggest for the F-35B; and we're not even with our backs to the wall in an emergency wartime situation...


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