F-35 Cancelled, then what ?

[SpazSinbad]

Turkey purchases two F-35 Lightning II aircraft at IDEF '13

Turkey purchases two F-35 Lightning II aircraft at IDEF '13 | 8 May 2013 /TODAY'S ZAMAN, ISTANBUL

Turkey purchases two F-35 Lightning II aircraft at IDEF '13

"Turkey's Undersecretariat for Defense Industries (SSM) signed an agreement on Wednesday with Lockheed Martin to make two additional purchases from the F-35 Lightning II family of aircraft, the world's only fifth generation multirole fighters, to be delivered by 2016...."

[JSFfan]

CM, you can lead a horse to water but...anyway I found test pilot Flynn who through EADS did the EuroFighter Typhoon, F-4 E/F, and Tornado, worth listening to from Webcasts
Looks like old dogs can learn new tricks

[Engines]

Courtney,

Sorry if I wasn't clear there, but I don't think those two statements conflict. Happy to discuss, though. There was no standard for wheel to hook distance - I remember going through the various specs with the arresting gear design team.

A number of US naval aircraft have had challenges with hook location, especially single engined types where you can only put the hook underneath the fuselage as far aft as the structure will allow. (The F-8 was a good example).

Wire trampling and whipping was also well known to the F-35 design team, which resulted in early studies into wire/tailplane clearances as well as influencing choice of tyre.

There is definitely an issue with the hook, and that issue showed up in testing. That's what testing is for. The hook damper changes were there to stop the excessive bouncing found in early tests. Yes, it will increase the force between the hook and the deck - but like everything else in engineering, there will be a tradeoff and the test team will find the best point for that.

The F-35 programme is taking place in an open reporting environment, which allows anyone to state their opinions. That's a good thing. So are facts.

Best Regards as ever

Engines

[Courtney Mil]

Engines,

No, no, not at all, my friend. My point was simply that, given the amount of detail available about the behaviour of the wire, I was surprised that there wasn't a better understanding of what problems might (and eventually did) arise with the F-35C mainwheel to hook shoe distance. As you say, testing is to find the problems as well as the good stuff.

Your comment about increasing deck/shoe wear is exactly to point I was trying to make. And, of course, the fact that increasing the downward force alone is clearly not going to solve the problem. I'm pretty confident that the engineers can find a way to make it work - after all, compared to a lot of the challenges in getting the programme this far, the hook design shouldn't be a show stopper for them.

As ever,

Courtney

[glad rag]

Stealth classification....vlo/lo

So, what did the F35 start out as, and if it did "change" it's classification when was that and why?

[SpazSinbad]

“...reproduce a radius on the toe of the hook with a 'rasp' after frequent contact with the deck wore it to a knife edge which, to the consternation of the 'Stokers' responsible for the 'trap', were required to replace arrestor wires which had been cut [knicked].” Ray ‘Dutchy’ Brauer A4G Maintainer VF-805

The first image of how the hook is going to change (to look more like an A-4 hook - added to original graphic - rather than a Hornet hook) is from this PDF whilst the second image shows the original F-35C hook gubbins:

http://www.aviationweek.com/media/pd...ern-report.pdf

[JSFfan]

It hasn't changed....the f-35 is a low observable platform and is also an all aspect VLO plane that has exceeded it's 'stealth' KPP
In house 'stealth' platforms are called LO, it's in the public domain things gets confused by those that aren't familiar with the terms and how they can be applied.
I remember there was public confusion a few years ago, but was clarified

expanding on my reference to the f-22 being a LO platform
https://www.google.com.au/search?q=l...ient=firefox-a

[Courtney Mil]

Glad Rag,

The F-35 was always supposed to be VLO, but was downgraded to LO in 2006. There followed a number of high level questions as to why and pressure to restore the VLO classification, which led to some hasty redefinitions and a return to VLO status. However, the issue wouldn't go away and suspissions led some to question whether the company was "watering down the low-observable characteristics of planes bound for non-DoD buyers". Burbage et al have always been a bit vague about answering that in public.

As it stood at the end of last year its RCS was accepted as being bigger than the F-22 despite being a smaller airframe. I don't think that was really news as it's pretty much what was expected. As for differences in export versions, again, we probably shouldn't be too surprised.

Courtney

[SpazSinbad]

'Courtney Mil' this furphy: "... As for differences in export versions, again, we probably shouldn't be too surprised." has been laid to rest already.

[JSFfan]

cm, please don't make things up...it has been repeatably said there is no RCS difference in export unless the customer changed the outer line by additions..there is no vagueness just naysayers woffle

[Heathrow Harry]

Engines wrote:- "Bottom line - they didn't 'get it wrong'. "


Actually they quite clearly DID get it wong - it didn't work

Maybe their methodology was, at the time, though to be correct but real life showed it wasn't

Like Courtney I'm just surprised that there is so little apparent research into such an important and obvious issue........ seems to be a "Suck it and see" approach

[glad rag]

Having been involved in certain UK projects AND knowing "the way things are" I will be very surprised if US aircraft do not have some particular advantage.

[JSFfan]

I wouldn't be surprised either, but what we are talking about is RCS and the RCS is the same on the planes. Unless the customer changes it by adding a drag shoot for example
why do you have so much trouble? it seems it doesn't fit what you want it to be.

CM I tried to source your 2006 reference and came up with WIKI? based on what APA clown club said and corrected by ADF

In 2006, the F-35 was downgraded from "very low observable" to "low observable", a change former RAAF flight test engineer Peter Goon likened to increasing the radar cross section from a marble to a beach ball.[132] A Parliamentary Inquiry asked what was the re-categorization of the terminology in the United States such that the rating was changed from "very low observable" to "low observable". The Department of Defence said that the change in categorization by the U.S. was due to a revision in procedures for discussing stealth platforms in a public document. Decision to re-categorize in the public domain has now been reversed; subsequent publicly released material has categorized the JSF as very low observable (VLO).[133]

[glad rag]

The problem, JSFfan, is the aircraft lineage and the changed specifications that have led us to where we are today.

Simple question, pit both a US 4th gen and a F35 together, both at their respective best fighting weights and pick your goalposts.

Would the F35 prevail?

[JSFfan]

mate, you will believe what you want to, there are enough facts in this thread if you want to read them...including the LER of 6:1 4 vs 8 advanced 4th gen

[SpazSinbad]

Hook Design Research and Test, Redesign and Test Again Etc.

For 'Heathrow Hairy': "...Like Courtney I'm just surprised that there is so little apparent research into such an important and obvious issue........ seems to be a "Suck it and see" approach". Yes there is a lot of research, testing and redesign with further testing as indicated in the material below.

A Study of the Aircraft Arresting-Hook Bounce Problem By J. THOMLINSON, Ph.D. May 1954

http://naca.central.cranfield.ac.uk/...rc/rm/2980.pdf

"SUMMARY: The kinematics of an arresting-hook unit are studied in order to determine, within the limits of the assumption of a perfectly rigid hook unit, the damper force necessary to control hook bounce. The necessity for a smooth deck and the desirability of small trail angle for the hook unit are demonstrated from several aspects. The design requirements for a hook damper unit are discussed in all their functional aspects and methods are given for determining the up-swing motion of an arresting hook unit immediately following engagement of an arresting wire. The behaviour of arresting wires after being depressed by the passage of aircraft wheels is also outlined...."
__________________

A Brief History of Tailhook Design 16 Dec 2011 by Tommy H. Thomason

http://thanlont.blagspot.com/2011/12...ok-design.html [change 'blag']
___________________________

How hook arrangements change - First Skyhawk mockup with 'yoked' hook design:

http://a4skyhawk.org/sites/a4skyhawk...y/137812m1.jpg
________________________

Som USN MilSpec re 'Arrested Landing Gear':

http://www.everyspec.com/MIL-SPECS/M...17C.018182.PDF
__________________________

Unnatural Acts of Landing Patuxent River Naval Air Museum Association
The Kneeboard Mag'n Spring 2012

http://api.ning.com/files/8OBnZkm85r...Spring2012.pdf

-“For most people, the idea of flight testing means seeing how fast an airplane can go or how quickly it can maneuver. While answering these questions may be part of a flight test program, there is more to flight testing than speed and agility. Navy carrier aircraft must also withstand the stressful loads of repeated arrested landings (traps) that can exceed 6 Gs on the aircraft.

The landing gear must:
- Survive thousands of landing shocks
- Reduce the loads reaching the aircraft structures and crew
- Allow the pilot to stay in control of the aircraft’s behavior

Ground Loads Testing shows that an aircraft structure can withstand carrier operations at maximum takeoff and landing weights. Normal landings at these conditions are no problem. But testing must also show that an aircraft can absorb these loads when:
- Its sink rate (how fast it descends) is high (as much as 26 feet per second!)
- Its wings are not level when it lands
- Its tailhook catches an arresting cable to the side of the center line
- The carrier deck pitches and heaves...

...During Super Hornet development, Ground Loads Testing required 125 test flights, 370 catapult launches, 471 traps, & 3 years to complete. Incidents included blown tires & various airplane parts (other than the wheels & tailhook) hitting the deck."
&
"What Is a “High Trap”? Normally when an aircraft “traps” (lands on a carrier), its wheels contact the deck (or the runway during practice landings) just before the tailhook snags the arresting cable. But sometimes the tailhook will engage the arresting cable before the wheels touch down. This is known as an “inflight engagement” or “high trap.” Both the aircraft and the pilot are slammed down hard as the aircraft is suddenly snatched from the air. These are not fun landings.”

Click thumbnail for an unnatural act:

[Courtney Mil]

Originally Posted by Glad Rag

Simple question, pit both a US 4th gen and a F35 together, both at their respective best fighting weights and pick your goalposts. Would the F35 prevail?

The answer, unfortunately, is not quite so simple, though. Let me illustrate. If you went many v many wvr against, say, F-15C, the F-35 would probably not come off too well because of its max sustained g and the fact that it's not optimized for air-to-air and would have limited a-a weapons, et, etc. But that is also not where it is designed to fight. Moreover, it's multi-role so simply measuring it's a-a KILL RATIO isn't really meaningful.

In modeling or evaluation terms, putting 'blue' up against 'blue' isn't a recognized method. If you want to evaluate a number of types (let's say competitors for a defence contract), you devise your trials so that you put each type up against a fixed 'red' adversary and compare the results in terms of kill ratio and mission success. You use a variety of representitive scenarios, support assets and geolocations. The results expose the strengths and weaknesses of each type - provided the scenarios have been properly devised - the results aren't always what you'd predict.

Just for fun, the F-15C vs F-35B BVR fight would be interesting, though. The air-superiority ac will throw his slammer further, faster, higher and will produce better defensive manoeuvre. The MR jet only gets a couple of shots, but if it uses its LO properly may get first launch. For political reasons, no one would ever let that fight take place in public, certainly without stacking the odds for obvious reasons. And who could blame them?

[PhilipG]

Spaz, it would seem that there has been quite a lot of work on hook bounce etc, dating back as you show to the mid 1950's. It would seem slightly remiss of LM and whoever it was in the USN not to have taken heed of what the papers say.
What will the USN do if come the next set of trials the hook does not work? Will they be rejoicing that the carriers can remain lean manned as there will only be Hornets and Super Hornets, so less maintenance teams needed, or will they insist that the shape of the F35 is changed to accept a fit for purpose hook? I do hate to think what the cost of a total redesign of the rear end of the C would cost.

[Courtney Mil]

Indeed, PhilipG, hence my discomfort with the statements 'there was no standard for wheel to hook distance' and 'wire trampling and whipping is a well appreciated phenomenon' so close together in this context.

As for not getting it to work, well, it is only a hook and we've been building them for years. In this case, though, there a set of unusual constraints: the mainwheels are long way back because of the size of the weapons bays and the hook has to have a low RCS when stowed (presumably it doesn't matter so much when its lowered). The first of these makes it comparatively short and places the shoe close behind the mainwheels. As it's a Naval variant, the hook needs to be agile too in order to keep the ship's landing rate up.

None of that is to say that you're not right to ask the 'what if' question, PhilipG.

[PhilipG]

CM, I hear and fully understand what you are saying, I also appreciate why the hook is not catching the wire. I think my point was If the redesign does not work, what happens? Are LM obliged at their cost to redesign the rear end of the C so that there is enough room between the wheels and the hook and does this change of shape get carried forward to the A and B models? In my perception the time and cost to do this this late in the process would be astronomical.
Or does LM say to the USN "Sorry Mate its too difficult, we cannot get the carrier version to land on a carrier." This would make some contracts interesting.
If this is the situation, I suppose we Brits can breath a sigh of relief that we did not have the design of the Prince of Wales altered to have EMALS installed to launch the C, as well as having the wires installed to let it allegedly land back on.
Fingers crossed for the B and let us hope that the SRVL system works as advertised, by LM.