F-35 the QE and SRVL BOLTERS

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jessmo111

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Unread post16 Apr 2016, 08:26

I have recently seen a really good question brought up, that no one seems to have the answers too.

Philip at PPRUNE recently asked a bold question:

Engines et al,

As far as I am aware when the F35B goes to sea on a QEC class carrier, it will be the first time ever that in normal operations that an aircraft has been embarked that will normally be expected to do SSLs.

We are all aware that the weight limits for the F35B are tight and that the undercarriage is not as robust as on F35Cs, what some of us are reasonably concerned about is will the F35B be able to SSL on a QEC, as well as take off on the ski jump with a defined weapons and fuel load.

As far as I am aware there is no evidence that an F35B has been shown to land on the area of a QEC deck doing an SSL, loaded or unloaded. The serious maths might have been done about how the F35B will perform off a ski jump but it has as far as I am aware yet to be demonstrated by a test or development aircraft.

By demonstrated here I mean two things, that the airframe, cracks and all, can withstand the loadings of going through these evolutions and that the software solution does not get itself into an inappropriate state when these evolutions are attempted.

The Barriers bit was unless many of us have read the SSL procedure incorrectly, that we understand that the F35B approaches the rear of the carrier with both forward motion lift and vertical lift, when the F35 is over the deck of the carrier and the wheels have touched down, yes with on PoW with help from the Bedford Array, stopping power comes from the brakes, the engines go to idle I am assuming.

If there is a tyre blow out, brake failure, landing gear failure or some other unplanned occurrence, it would seem that the F35B would have the propensity to slide along the deck of the carrier and project itself into the sea, I do not think that it would be reasonable to rely on the ability of the engine to spool up to give enough power to do a vertical take off, having discarded any and all external stores, to give the damaged plane the opportunity to take off again. It just seemed sensible risk mitigating and indeed not rocket science that a proven method of stopping planes crashing on axial deck RN and USN aircraft carriers was investigated again.

I am sure that being taken by the barrier will cause structural damage to the F35B, let us hope that the damage is not as serious as kerbing a 1966 Mk1 Lotus Europa was, it meant writing it off, the body work was initially bonded to the chassis, saving a rather expensive aircraft and its pilot, would seem a good idea. I am sure that even the MoD would countenance the purchase of kits of spares to repair on-board F35Bs that have simply taken the barrier, far cheaper one hopes than buying a replacement.

Of course I am not suggesting in any way that the F35B is as fragile as a Seafire was at the beginning of its time as a fleet defence fighter, it would be interesting to know how many spitfire props the BPF, Task Force 57 et al got through, that is not for this thread.

I am sure that you can give us all comfort that all these risks have been theoretically mitigated, it would just be nice to know in the real world that these leading edge evolutions can be safely undertaken by normal FAA and RAF pilots, as they will be required to do with possibly not much sea training in a surge.

Philip

http://www.pprune.org/military-aviation ... t-309.html

Indeed How will the Uk handle bolters in SRVL type situations? it has to be.
A. Use barriers as mentioned above.
B. Try to get the engine to spool up.
C. Sing the OLD A-25 song as the sea approaches then punch out
http://sniff.numachi.com/pages/tiA25;ttVILDINAH.html

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Unread post16 Apr 2016, 09:04

This SRVL is discussed on a long running thread here. I reckon all the answers are there. Otherwise apart from computer simulation there is no way to actually test the SRVL until the CVF arrives near the east coast USofA in 2018 or thereabouts.

F-35B UK SRVL info - Updated when new/old info available: viewtopic.php?f=22&t=20304&p=230592&hilit=SRVL#p230592 [there are 25 pages of discussion goodness therein]
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Unread post16 Apr 2016, 11:13

As was pointed out in an earlier thread the SRVL landing speed of the F-35B would be about 60-70mph. That's a lot slower then any other carrier based aircraft I can think of. If there was a tire blowout, or landing gear failure it's slower speed would make it more controllable then other aircraft that come in a lot hotter. It would be interesting to know how many Harrier's went off the deck in the situation your describing. Pilots are reporting that that the F-35B is much easier to handle then the Harrier, though in the situation your describing almost anything might happen.

I think your premise that the B model doesn't have a strengthened fuselage and landing gear is not correct. The B model was designed for just these kinds of operations from small carriers, and amphibious ships. USMC F-35B's will also be operating from the decks of USN Supercarriers along with the C model. I also find it hard to imagine that a net barrier would destroy an F-35B. By the time it hit the net it might only be going 40mph. This is an aircraft rated to handle 7.5 G's, it's not made out of fiberglass, and aluminum.
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Unread post16 Apr 2016, 11:20

Always best to quote IAS because that is how aircraft fly through the air but the long 25 page thread describes in a lot of detail how an SRVL will be performed as a FLEXIBLE maneuver according to conditions at the time. IF the conditions are not suitable then the aircraft will dump unwanted weight to carry out a vertical landing. Yes a tire blowout may be an issue however these things are investigated and mitigated and again if dangerous it won't happen. BOLTERs and potential for same are different and best search the other thread for 'bolter' to get the gist of it. And again it is not likely. Video explains how easy it will be. Do not be afraid. SRVLs may not be required. It all depends. The aircraft has come to a halt by the deck mark line just to right in this screenshot from time: 1 minute 23 seconds, viewpoint FLYCO island. And... from guesswhere a plan view of dedeck: viewtopic.php?f=22&t=20304&p=240608&hilit=Tooms#p240608 Graphic: download/file.php?id=16794&t=1

The graphic showing the comparison between CVF & CVS deck acreage makes it clear about some questions I hope:

http://www.aircraftcarrieralliance.co.u ... rosyth.jpg

"...It would be interesting to know how many Harrier's went off the deck in the situation your describing...."

Only one rolling Harrier ship deck landing was carried out for operational reasons and it was dicey as described in the other thread.

viewtopic.php?f=22&t=20304&p=305042&hilit=David+Morgan#p305042

The Harrier was not designed for such ship deck landings so it carried out vertical landings on ships. When ashore with suitable runways it could fly a rolling landing (also described in the other thread). The aircraft Harrier/F-35B have quite different undercarriages. BTW if 'Engines' replies on the pPrune thread it will be good. Search the other SRVL thread here for some 'Engines' good stuff. For example: viewtopic.php?f=22&t=20304&p=266548&hilit=Engines#p266548 OR viewtopic.php?f=22&t=20304&p=253301&hilit=Engines#p253301 OR viewtopic.php?f=22&t=20304&p=240231&hilit=Engines#p240231



Attachments
SRVLstopDistance.jpg
CVFdeckPlanF-35BskiJumpSTOPdistance.gif
CVF&CVSsizeDECKcomparo.jpg
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Unread post17 Apr 2016, 08:14

I almost forgot that the F-35B has a auto- ejection system. I can imagine, that an unrecoverable sink rate might trigger it.
viewtopic.php?f=60&t=27447&p=308765&hilit=Auto+eject#p308765
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Unread post17 Apr 2016, 08:19

Engines adds something else. It appears naval AVEEATORS have an innate skill at egressing a plane in dire circumstances.
One would say they are some of the best at it:

Glad, Courtney and others,

Please be as sceptical as you wish - open forum and all that. I don't 'always' cover things - if I don't know, i say so. Or try to.Sorry if I'm not clear enough sometimes.

Deck coefficient of friction is well understood and the expected values are known. The USN have always had much better deck coatings than the UK, at higher cost. The question of mu has been addressed - in that the team know what it should be if the coatings go on as per spec. And they know what the F-35B landing gear will produce. It's been tested - like most everything else.

A small point of clarification - I was on the deck of Invincible when the Sea Harrier went over the side. Wasn't all about mu. Here are the facts - be as sceptical as you want.

The aircraft was on the runway about to launch against a suspected incoming threat. (So no lashings fitted). Fully loaded. The ship had to manoeuvre quickly to get on to the flying course, and went hard starboard in a biggish sea. We started heeling over to port. Quickly. The angle of heel was somewhere around 10 to 15 degrees - possibly a bit more. Lots. Enough to get everyone on deck grabbing for something to hold on. High wind also from starboard, coming round on to the bow.

It was at this point that the FAA learned something about the Harrier nose leg not covered in any of the manuals. It had a break out design so that excessive side forces weren't fed into the airframe. So, even though it was centred for launch, as the side loads came on it suddenly (and I mean suddenly) castored, allowing the aircraft to (very quickly) rotate around the main wheel assembly to port. Deck was still heeling over to port.

This was the point at which mu came into play. The flight deck was, by this time, fairly dirty and slick. (We had no effective deck scrubbing kit at that time). So, as the aircraft nose wheel went over the side of the deck, there was very little to stop the aircraft sliding to port and simply jumping over the side, clearing the catwalk as it went. Pilot ejected at around 45 degrees nose down, recovered by a Sea King that was standing off waiting to recover. (Good work in hefty seas by the way).

Lessons learned very quickly:

1. Get the deck scrubbed and keep scrubbing. An old FAA routine that we had forgotten through not doing carrier aviation for a few years. Deck scrubbing machines were procured immediately and are still in constant use.
2. Restrict ship manoeuvring when aircraft not tied down on deck. See above.
3. Stuff happens in war.

It should (but probably won't) go without saying that the F-35B's landing gear is massively better for deck work than the Sea Harrier's somewhat 'hokey' 1950s style bicycle layout. Brakes that work, and a stable tricycle layout. Moreover, QEC will not move around at anything like the amount the CVs did.

But are there risks in SSLs? Sure there are. The team are working those with all the techniques at their disposal. Deck trials will be the final proof. But they won't even take place unless the teams have wrung out all the data as far as they can first. The fact that they are still going forward with SSLs should tell us that they haven't found a 'stopper' yet.

I hope this stuff helps a little. I'll now desist further posts on this subject, as I think I'm at the point when I'll start repeating myself. And few will listen - I don't blame them.

Best Regards as ever to those who have actually worked on seagoing STOVL and have the knowledge

Engines

1. I have no doubt that the F-35Bs gear is ALOT beefier than the poor Av-8
2. I have No doubt that safety issues have been addressed. (see comments above on auto-eject)

I think the real burning question is if NAVAIR will try SRVL on the smaller, and more crowded gator boats.
P.S. ENGINES is a stand up guy. I hope we can get him here.

http://www.pprune.org/military-aviation ... t-310.html
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Unread post17 Apr 2016, 09:42

'jessmo111' there is an huge amount of information in the thread indicated as well as a PDF online which has even more detail about SRVLs (and Ski Jumps). Yes ENGINES knows stuff and is reliable for data/experience and explanations.
'jessmo111' said: "...I think the real burning question is if NAVAIR will try SRVL on the smaller, and more crowded gator boats. P.S. ENGINES is a stand up guy. I hope we can get him here."

'ENGINES' has not been here to my knowledge and he knows about this forum. The pPrune thread you quote is now old. Yes the USMC are interested in the outcome of SRVL trials however they have categorically said understandably that there will be no SRVLs on their LHAs - perhaps there is interest in an emergency SRVL on a CVN however there are no plans to operate F-35Bs on CVNs. USMC were made to buy/operate F-35Cs for this purpose (originally they required an ALL F-35B force [presumably operating some F-35Bs on CVNs]). Again read the other thread there is so much information there.

On Microsoft OneDrive (which requires downloaders to register for free) a 520 page 100Mb PDF titled 'F-35B VL & SRVL via VACC Harrier & Landing Aids pp520' is available for free download. It is in the folder '_SRVL & Ski Jump F-35B Information PDFs' which is here: https://onedrive.live.com/?id=CBCD63D63 ... D6340707E6

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09 Feb 2011 Graham Tomlinson

"...In the unlikely event of the lift fan failing catastrophically the aircraft would pitch inverted in 0.6 seconds, & the pilot is protected by auto-ejection signalled by pitch rate & attitude (derived from the YAK 38 & 141 systems)...."

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Unread post17 Apr 2016, 23:49

Google finds things & yet sometimes it doesn't - the lottery effect - meanwhile another pPrune thread with ENGINE input:

http://www.pprune.org/military-aviation ... ive-9.html
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Unread post18 Apr 2016, 00:44

SRVL is just an RVL -- routine for decades in Harrier and now in F-35B -- performed on a ship.

Principle feature of SRVL that obviates the need for beefy landing gear a la tailhook jets is the fact that one is landing at ~40kts ground speed (or less). That means that the target ROD at touchdown is far less than the design max ROD for landing.

Principle features of F-35B that allow contemplation of such a thing as SRVL are the ease and precision of aircraft handling -- target airspeed to 1 knot precision, and repeatable glide slope precision to a degree unattainable in Harrier. Line-up a bit more challenging than the aforementioned airspeed and glideslope but still light years different (easier) than Harrier because of the sterling handlings qualities of F-35B (the whole F-35 series actually).

Getting safely stopped after rolling landings in Harrier was always a challenge because the MLG only supports about 50% of the weight of the aircraft, and depending on one's speed and flap configuration the wing still wants to fly, thereby reducing limited brake effectiveness even further. F-35B is much, much easier but we're still talking about a ship -- i.e. limited real estate. That's why some of the world's best engineers and test pilots have been assessing, characterizing, cataloging, and mitigating the potential risks associated with RVL and it's derivative SRVL for several years.

In the future, when they 'couple' the approaches via JPALS or a JPALS-like system, the young guys might wonder what all the sweat was about behind the ship.

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