F-35B UK SRVL info - Updated when new/old info available

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madrat

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Unread post26 Dec 2012, 13:30

Brilliant sources, spaz. I don't know where you find the time, but it is admirable.

Do you think they will mainly operate the Royal Lightnings in low drag configurations while relying on SRVL? I would imagine any exterior load that doesn't have optimal glide ratios while underslung would pose some risk.
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spazsinbad

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Unread post26 Dec 2012, 13:38

'madrat' a lot of sources on this thread are repeated earlier elsewhere in other associated threads. At such a slow KIAS of 60 I do not believe any added drag is significant, whereas the extra drag probably helps keep engine RPM high (my guess) similar to that on older conventional carrier landing jet aircraft (which have speedbrakes out) to help keep engine RPM high for quick response. I guess these days with FADECs and terrific cross controls that mimic speedbrakes the same thing is achieved in a different way. There would be a limit to weight / drag combinations but again at such a slow approach speed such external store drag would not be significant for the F-35B.

I do not believe any carrier aircraft wants to glide at any time during a carrier approach except perhaps from 20,000 feet doing a fast descent to get to 'Charlie time'. Carrier approaches from the last couple of miles are done dirty at optimum angle of attack with engine RPM high. Going to idle/glide RPM is a recipe for making an underwater approach. Dirty/high drag is good within reason. It seems the F-35B has good excess power available. Going to low RPM in an F-35B SRVL approach will have the aircraft on the express down elevator. It is only semi-wingborne at that 60KIAS speed with the engine mostly holding it UP!

BTW most of the reference F-35/how deck land stuff is also seen in the 1GB PDF at GoogleDrive or earlier version on SkyDrive on the SpazSinbad page. Use the first two (TINY) URLs in my sig at bottom of each post here.
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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quicksilver

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Unread post26 Dec 2012, 15:16

spazsinbad wrote:What has that got to do with anything? Apparently in an actual SRVL (not carried out by the way - earlier only approaches to low waveoffs were carried out) only via computer simulation for the moment there is not a perceived problem. You seem to forget that the wind will be straight down the deck which is a very big benefit. Any ship movement is being adjusted for as explained by the Bedford Array abilities.

Different aircraft will have different taxi/wind speed restrictions with special precautions if it is deemed necessary to taxi (very slowly) in difficult wind conditions because during taxi on deck the ship may not be pointed into the wind and it may well be turning also. For an A4G wind conditions could be critical. Drifting from right to left just before touchdown on a moving deck was especially critical as evidenced by a movie / screenshot I believe already on this forum. I'll look for them.

However just making a question without any other detail at this stage is a little silly. What is your point about taxiing what aircraft on deck at 40 KIAS wheelspeed under what circumstances. I'll guess - NOT ONE. But then again I was not trying to land at that wheelspeed without being arrested. You sure do not understand what an SRVL is IMHO.


I have a full understanding of RVLs and their many potentialities dating from the early 80s -- that's how I can ask relevant questions that to this point have not been asked.

Ship operators don't let aircraft move around unrestrained on a flight deck at speeds greater than a fast walk because the risks of the jet heading in an unintended direction can be very high. Just because we're now calling this movement a landing of some kind doesn't mean that we've changed the inherent risks of a unrestrained jet moving on a flight deck at ~40 kts.

Winds around ships are highly variable even with the ship at a constant heading. The effect of this variability is, in relative terms, greater on an aircraft that is moving at only ~60 kts. Thus, we have to account for the potential impact of these variables. To date, no one in the public domain has done so.

You should also note that the USMC is not making any noise about SRVLs on big-deck amphibs either. Ever wonder why?
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whitewhale

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Unread post26 Dec 2012, 15:54

quicksilver wrote:

You should also note that the USMC is not making any noise about SRVLs on big-deck amphibs either. Ever wonder why?



The USMC have very much their own way of doing things, they never adopted ski jumps despite the unquestionable advantages it gave the Harrier. Not choosing SRVL is their own choice for how they do things any may change once testing is done.
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quicksilver

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Unread post26 Dec 2012, 16:21

The Marines were interested in SRVL when 'B' aboard the CVN was being considered. That interest was shelved with the planned purchase of 'C's that will say MARINES on the side.

The Marines are very much for anything that gives them more operational flexibility, particularly when it is essentially free (the UK is paying the bill). Any other guesses?
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Unread post26 Dec 2012, 16:47

I made no guesses in order to add any more, merely stated that the USMC do things their own way and that may change as testing hasn't finished.

Anymore guesses?
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spazsinbad

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Unread post26 Dec 2012, 18:03

'quicksilver' you make a lot of kerfuffle about SRVL when it is still under investigation. And as noted has been under investigation and design for a very long time. Shirley any questions you raise have been looked at by some very informed UK people over this long time. You make a lot about an aircraft being on a suitably long empty deck (except for parked aircraft out of the way) 'taxiing' at some speed. WHOA. Who in their right mind even on an empty CVN deck would accelerate to your suggested speeds and then slow down to stop? Nobody. There is no reason to do it either except for a free takeoff by the prop aircraft or any stranded jets capable of a free deck takeoff (accelerating without the braking mind).

You live in an odd world where variable winds prevail at sea. Light airs perhaps but otherwise the sea is noted for the steady wind except perhaps in a real storm. OK make my day fly in a storm. In that case the venerable F-35B will VL whilst the other fixed wingers go ashore. And despite your squeamishness about SRVL it may not happen as pointed out. But please inform us as to what is so bad.
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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Unread post26 Dec 2012, 22:35

Long screed (already posted on this forum) with detailed info on how the UK has been looking into SRVL with all the hazards it entails. There are many references to SRVLs while the excerpt below is only part of it. Scroll to the end of this page to the last long 'YourFather' post:

Date Posted: 11-Dec-2008 International Defence Review

http://militarynuts.com/index.php?showtopic=1507&st=120

"...Low-key studies to investigate the SRVL technique were initiated by the MoD in the late 1990s, but the work has latterly taken on a much higher profile after the MoD's Investments Approvals Board (IAB) in July 2006 directed that SRVL should be included in future development of the JCA design...

...Back to reality
Accordingly, the CVF IPT (now subsumed into the wider ACA) in 2005 put in place a package of work to investigate SRVL impact on the carrier design.

This comprised three workstrands: analysis to establish the optimal SRVL recovery deck; sortie generation rate modelling; and MITL simulator trials to establish the most appropriate recovery profile, analyse VLAs [Vertical Landing Aids] and measure landing scatter.

Two separate simulation trials were conducted at BAE Systems' Warton facility using a representative CVF ship model and a JSF representative air and ground model. The results indicated that, at night or in higher sea states (above Sea State 3), an SRVL-specific approach aid was desirable, and Ship Referenced Velocity Vector (SRVV) symbology in the pilot's helmet-mounted display was an enhancing feature.

One significant outcome of the JCA Review Note promulgated by the IAB in July 2006 was the decision to add an SRVL capability into the overall SDD programme. Significant work has been performed since then, including land-based flight trials and extensive simulator-based development and evaluation.

As part of this work, QinetiQ was in 2007 contracted to use its Harrier T.4 Vectored-thrust Advanced Aircraft Control (VAAC) testbed to perform representative land-based flight trials and a ship-based SRVL demonstration. The latter saw the VAAC aircraft perform a series of SRVL recoveries aboard the French carrier Charles de Gaulle in June 2007.

According to the MoD, these flight trials "demonstrated that SRVL was a safe recovery method to the ship at Sea State 6 in day, visual conditions", although it added that Charles de Gaulle is a "particularly stable ship" and there is "no ship motion data to enable comparison to how CVF will react in the same sea conditions".

Other forthcoming work will include further investigations on an SRVL clearance aboard CVF, optimisation of the approach profile, reaching an agreement on the optimal post-touchdown technique, and mitigation for failure cases such as a burst tyre on touchdown.

Work is also to 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, Rosa said, while acknowledging that the "exact scope of capability is only likely to be confirmed after First of Class Flying Trials" aboard CVF...."
OR
Youse can go here for the entire post also:
Possibility small STOVL carrier USN/USMC AKA 'the very long thread'
http://www.f-16.net/index.php?name=PNph ... iab#172162
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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Unread post26 Dec 2012, 22:41

Rolling Recovery JDW 04 March 2009 by Richard Scott PAGES 26-29

http://www.zinio.com/reader.jsp?issue=3 ... v=sub&p=26

"The science behind the Bedford Array - so called because it was brainstormed at QinetiQ's Bedford lab - is deceptively simple. A linear array of software-controlled lights is installed along the centreline of the axial flight deck, using a simple mathematical algorithm to switch on the appropriate lights according to the ship motion reference input to the system. These provide a stabilised glideslope indication for the pilot's helmet display SRVV symbology.

"The system ensures that the pilot flying the 'rolling landings' makes an accurate approach to the deck, even in rough sea conditions," said Paines. "It takes inputs from external passive references and when combined with information in the pilot's Helmet Mounted Display, allows for a low-workload, stabilised pilot approach in even the worst conditions."

Nice graphics (already posted) and worth going to URL to read it all - as usual.
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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Unread post27 Dec 2012, 02:30

Attachments
BachmannSRVLtrainingUKsim+Text.gif
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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Unread post27 Dec 2012, 11:11

Never Mind the Quality (of the cloth) - Feel the Width (of the cloth). Old English Vaudeville Tailor Joke.

http://www.aircraftcarrieralliance.co.u ... rosyth.jpg
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CVF-CVScomparoDeckSizeWidthEspecially.jpg
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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KamenRiderBlade

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Unread post27 Dec 2012, 16:19

That is wide
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Unread post27 Dec 2012, 19:57

It is a fairly early render and may not be entirely 100% accurate but the CVF definitely has a focus on a wide usable surface area, specifications for required OP rates and time between landings and take offs have been important considerations for the 'surge' elements and played into the design. The RN were eager to have a specific sortie rate and joint helicopter / jet capability early on and that is still in force today as part of the consideration of SRVL. IT is not just bring back but the effect it may have on landing rate and whether it would excessively hinder other on deck operations.

With the deck area and ski jump the CVF is a bit of a odd beast so the RN investigating other options for launchings and landings could provide some interesting results, some people scoffed at the idea of a ship having a flat deck purely for aircraft and declared it a waste of time and money but until you try you never know.
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Unread post27 Dec 2012, 21:40

Yes 'whitewhale' perhaps the USMC flat decks could have benefited from a ski jump - not only for safety during takeoff reasons - but also to be able to have a portion of the aft deck available for concurrent helo ops. A failed dream for some [not me - I give up] these days but one never knows. :D
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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Unread post28 Dec 2012, 16:05

spazsinbad wrote:'quicksilver' you make a lot of kerfuffle about SRVL when it is still under investigation. And as noted has been under investigation and design for a very long time. Shirley any questions you raise have been looked at by some very informed UK people over this long time. You make a lot about an aircraft being on a suitably long empty deck (except for parked aircraft out of the way) 'taxiing' at some speed. WHOA. Who in their right mind even on an empty CVN deck would accelerate to your suggested speeds and then slow down to stop? Nobody. There is no reason to do it either except for a free takeoff by the prop aircraft or any stranded jets capable of a free deck takeoff (accelerating without the braking mind).

You live in an odd world where variable winds prevail at sea. Light airs perhaps but otherwise the sea is noted for the steady wind except perhaps in a real storm. OK make my day fly in a storm. In that case the venerable F-35B will VL whilst the other fixed wingers go ashore. And despite your squeamishness about SRVL it may not happen as pointed out. But please inform us as to what is so bad.


Spaz, I've been to the rodeo -- actually rode in it many, many times. I've heard the briefs -- in person. No one has uttered a peep about deck roll and lateral motion of the aircraft before and after touchdown. Nor about the effects of variable winds on STOVL jets doing RVLs on ships. The focus has been exclusively on roll-out distance.

The reason jets don't taxi around on a flight deck faster than a brisk walk is because it's beyond dangerous. So now, someone wants to have a jet moving on a flight deck at 40ish kts unrestrained by anything but its brakes. Oh, and the deck will be wet and oily and the non-skid will be worn to near bare metal. And the winds will swirl and gust around the bow, the cat walks, the ski-jump, and other aircraft on the deck and yeah, the beast will roll. Get the picture?
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