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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. |
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. Too bad the old, 'it's better to stop and the land, than land and then stop', idea seems to be, being eroded. |
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. |
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. |
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? |
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. . |
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 |
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. |
"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. |
That´s what professional pilots are for. |
Engines:
SRVLs are most probably being looked at because the Brits want the aircraft to do more than the agreed specification asks for. 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%. Assessing Progress on the Joint Strike Fighter Program shows how the baseline weapons fit has been steadily whittled away since 2001. |
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.
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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.
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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. |
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? |
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.
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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....... |
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. 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.” 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) |
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? |
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... |
but then we do want to retain an organic defence/aerospace manufacturing capability dont we? It would be diabolical if Dave-B became another Spey Phantom debacle. Should it turn out that SRVL is a tricky manouver, even the advantage of reduced time spent practicing landing will be lost. And the penalties of vertical lift are then going to be very hard to justify. Of course by that time the carriers will be built, (even now the excuses for how difficult it will be to retrofit the new carriers with CATS are being rehearsed) and Dave-B WILL go ahead regardless. As I recalled in the Future Carrier thread; the Spey Phantom was always going to pay for itself in exports to re-engine F4s the world over. In fact, it did no such thing, and the RAF ended up with the worlds slowest, and most expensive F4s, all 'justified' by an alleged need to generate a bit more thrust to improve bolter performance. I would suggest that the rational for Dave-B is starting to look at least as tenuous. |
jetex - simple question:
Do you know what the procurement and through life costs of Dave-B are compared to that of Typhoon? If you did and it was your choice you'd have Daves coming out of your armpits! oh oh ..... can't help this postis going to be used extensively for quotes....incoming! |
There's a lot of supposition going on here - and that's OK, it's a discussion forum. However, some of it is a bit wide of the mark.
SRVL relative approach speed to the deck is around the 40 knot mark, I guess. The available landing area on CVF is generous (especially if we were to use an angled landing area) and the F-35B brakes are extremely powerful. Distance from the round down to the touch down point will be a key parameter. The guys working this are not going to recommend an unsafe landing method to justify buying the B. The TPs involved are experienced, smart and operationally aware. They are working to devise a safe manual technique that can be easily automated to improve safety - very much as the USN do for their cat and trap operations. Spey Phantom - yes, definitely a good bit of work for RR, in the wake of TSR2, P1154 and HS681 cancellation. But the driver for the UK changes was the need to get the aircraft off the shorter catapults and slower carriers the UK had in the 60s. In addition, Bolter performance was a very real issue. Landing gear was beefed up and heavily modified, more weight and so more thrust required. The problem was taking an aircraft designed in detail to operate from the USN CVN flight deck, and trying to get it to work from a smaller deck on a slower ship. When looking at taking F-35C and putting it on CVF, we could consider this piece of history.... |
Dirty B
Do you know what the procurement and through life costs of Dave-B are compared to that of Typhoon? In any case, isn't it a little too early in the project lifecycle for anyone to say what the procurement and life cycle cost are really going to be? And that's just thinking about the cost of the aircraft. If we adopt the view that in order to justify developing Dave-B we have had to buy a couple of STOVL carriers, we add in another big chunk of change. I'd like to see an analysis of the cost of fully automating Dave-C CAT/TRAP landings. If it's possible, and cheaper than developing Dave-B it becomes a no-brainer right? More capability, without the need to wear out the airframes practicing the basics of carrier recovery. |
Jetex - true, but.....
Dave was designed to meet Defence Strategic Guidence 05 (and previous instantiations) and did so in spades. Dave C did it in bigger spades but cost more so it was a no-brainer to go for the cheaper version (from what I've heard!). |
Granted,
I thought the 'near crawl' approach of 140kts - rather than the more likely sounding 40kts was a bit dubious. As mentioned previously, the VAAC Harrier ( thus leading to the F-35 systems ) and to some extent the F-18E, UAV's etc have 'autoland'. 'Bring-back' seems likely to remain an issue for carrier aircraft, no matter how they land, be it cat & trap, vertically or on a rubber mat alongside ! |
F-35C is designed to operate from USN ships - CVN-68 class (Nimitz). They will be designed to use the new JPALS landing system, and it will have an autoland capability.
BUT - there is very little chance that the USN will rely only on an automatic landing system to avoid training aircrew in manual landings. F-35C CONOPS will be a development of those used for F/A-18E/F and other manned jets. Trying to go for an F-35C option without training our aircrew would be, in my view, plain unsafe. I'd suggest that the autoland issue is not the central one for SRVLs. (The one area where it might pay off is a automated braking function). The teams at Fort Worth and Warton are, I believe, working to develop a safe SRVL capability which can be carried out manually. JPALS could then be used to provide various levels of assistance, depending on weather and operational needs. Hope this helps, Engines |
Engines.
Yes the Spey story is a good one. For RR. On the strength of equipping the ARK with its single squadron of F4Ks, the entire UK F4 buy were equipped with Speys. Which cost about twice what the standard F4J was then going for. Amazingingly enough, sufficient to have procured three new carriers, (with decent sized decks) I believe. That the Spey Phantoms were pretty duff can be seen from the fact that the Air Force got rid of 'em with almost indecent haste, (to replace 'em with the lovely F3, of course) And the Luftwaffe has only just retired the last of its ancient F4s, but even these were not too shabby at the end, with AMRAAM and decent radar. When looking at taking F-35C and putting it on CVF, we could consider this piece of history.... Plus of course by going ski jump we then have to make do with rotary wing early warning aircraft, the frenchies have E2C, and so it goes on... |
Engines, could you remind us all what the term co-efficient of friction refers to please?
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Jetex - I hope they haven't quite retired the last of their F-4s, as I'm pretty confident there's one coming to an airshow north of the border in the none to distant future....
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regarding the braking system - do any aircraft/could this one be designed to have ABS type systems?
How about install some very large fans/blowers on the bow of the ship to increase the WOD during finals :-) Or if bringback is such a driver for SRVL, tow a large dinghy behind the CVF and jettison stores before transition......I'll get my coat! |
QA - most fast jet a/c have an "anti-skid" system of some kind or another. The main drama with it compared to your common garden ABS is that braking is only being applied to two wheels, thus the ABS sensor system only has two wheels to compare. Thus if you have a snag with it it can lead to you getting no braking at all!
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Jetex - I hope they haven't quite retired the last of their F-4s, as I'm pretty confident there's one coming to an airshow north of the border in the none to distant future.... |
Good point about the μ factor of a wet, kerosened deck. Particularly in lively sea states.
Perhaps a hook-like thing on the arse end of the jet and some wires across the deck might be in order? |
BUT - there is very little chance that the USN will rely only on an automatic landing system to avoid training aircrew in manual landings.
Avoiding aircrew training isn't the point of an automated aircraft carrier landing system. ( At least that's what they tell naval aviators. ) It's there to make landings possible in worse weather, and to assist an aviator in distress for whatever reason when necessary. Would you say that existing IFR equipment is there to avoid crew training? Now, everyone who's for skipping the F-35 and moving on to shipborne UCAV's please raise your hand. |
Modern Elmo
Don't think a complete fleet makeup of UAV's is the way to go as both manned and unmanned can REALLY complement each other operationally.
However.. ....If you look at the toll of US Naval aircraft landing on bolters/incidents/accidents with aircraft who, for want of a better term, "relatively simple landing phase systems" (sorry) how do you see the complicated setup of the JSF coping? (IMO it's a fudge) |
Glad Rag and others,
The JSF team are definitely considering deck conditions, including coefficient of friction. The USN take quite good care of their landing areas, incidentally, with frequent washes and prompt removal of fuel and oil. UK should do the same with CVF. JSF has a very advanced braking system, large wheels and substantial brake units. Braking performance at 40 to 50 knots is good, and the system is designed to handle wet surfaces as best as laws of physics will permit. ME, landing aircraft on CVNs with wires at 140 knots is a hazardous undertaking and not at all simple. The USN keeps accident rates low with very good aircrew, lots of very good training, lots of practice at sea, closely managed authorizations (takes a while to get night qualified and hard work to keep it) and well worked up CVN crews to run the ATC, approach, autoland and arresting systems. They are the masters at it, but it costs a fortune to do it. JJ - Rafale performance off CdG is rumoured to be not good. The cats are a shortened version of the USN pattern, giving lower launch speeds. A problem, especially as CdG is not a fast ship. Spey buy - the F-4K buy had to equip the RN's complete fleet, a lot more than one squadron. In the end, the F-4K/F-4M split was about 50/50. Yes, it was a job creation scheme for RR - but as I said, the only real way to get F-4s to sea on UK ships. The USN had already learned that trying to convert WW2 ships to handle F-4s and larger (A-3 and A-5) was not a good way to go. Sadly, the UK just could not afford Forrestal class ships. Best Regards Engines |
One thing I haven't seen mentioned yet - sorry if I missed it ! - is why on earth the SRVL is a 'new' idea, not designed in from the start ?
We all know Harriers like to creep forward on landing ( and certainly a bit more for take-off ! ) for reasons of hot gas re-ingestion & FOD, maybe a little wing lift - you tell me, I'm not a Harrier pilot... Maybe the F-35B doesn't suffer as badly from hot gas into the intakes as the Harrier, what with the fan rather than close nozzles ( even the aft hot ones ). Another point raised by a very accomplished VSTOL aircraft researcher is " how does it taxy backwards ?"- using braking Viffing - for landing rather than combat manouvres largely invented by the media - also handy for deck parking, though not easy, as related by Jerry Pook. My father was crew-chief on a Harrier at the Paris Salon show, and after one attempt at taxying backwards then finding out the reverse castoring effect on the noseleg the hard way, it was quietly decided by all concerned to forget it unless the pilot had someone ahead directing - obviously a different deal on a carrier at war. However braking / reverse parking thrust would seem handy to me. As for the weight issue, remember the P1127 could barely lift itself when stripped right down to start with, but the Pegasus ended up with a lot more than twice that thrust ! |
Engines, I beg to differ, regarding your numbers of Spey Phantoms
from Military Power: F-4 Phantom II In 1964, the Royal Navy ordered a 'anglicized' F4K, which had a wider fuselage to house the Rolls-Royce Spey, fan engines. Forty-eight machines were delivered to the United Kingdom as the Phantom FG.1. However the premature retirement of the Carrier HMS Victorious coupled with the prohibitive cost of refitting HMS Eagle meant that only the carrier HMS Ark Royal was available to operate the Phantom. As a result twenty aircraft of this order were transferred to RAF Strike Command, equipping No. 43 squadron at Leuchars. The twenty eight Royal Navy aircraft began trials by No.700P squadron based at Yeovilton in Devon before being passed to No.767 squadron for type conversion training, and finally becoming operational with No.892 squadron, also at Yeovilton. From March 1969 No.892 squadron made a number of cruises with these aircraft aboard HMS Ark Royal using the Phantom. In 1978 these aircraft were transferred to the RAF'S No.111 Squadron for Air Defense of the United Kingdom.....The use of Rolls-Royce Spey engines in the British Phantoms dramatically increased the unit price of the aircraft whilst decreasing maximum speed, height and performance at altitude. Pretty pricey cocktails. |
based at Yeovilton in Devon finally becoming operational with No.892 squadron, also at Yeovilton Blimey!!! Not only did they transfer tho 'Tooms to the RAF in order to cut costs, they also seem to have managed the spectacular feat of moving Yeoves from Devon to a county nearer to London too!!! Just think what could be achieved if we were still using Lsd............. |
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