F35 to display in the UK this year.

[mmitch]

A F35 is to display at the RIAT and Farnborough this year.
F-35 Lightning II Jet to make Maiden British Flight (http://www.raf.mod.uk/news/archive/f35-lightning-ii-jet-to-make-maiden-british-flight-17042014)
mmitch.

[RAFEngO74to09]

Here's a video of the first F-35B public airshow display at MCAS Yuma 2014:

https://www.youtube.com/watch?v=yRtPtcAaULk

[Darren_P]

Looks a real crowd pleaser.

[Willard Whyte]

Hmmm, so many doors, hinges, swivelly bits - all having to work together, every time, without fail...

As one particular 'engineer' might say: "The more they overthink the plumbing, the easier it is to stop up the drain."

[newt]

If it looks right, it flies right!

Not a chance! No high speed pass. No inverted flight! Very large turn radius!

It's a joke! The Lightning was much more impressive and I suspect, more fun to fly!:ugh::ugh::ugh:

[Rhino power]

Looks a real crowd pleaser...

Only if you're very easily pleased!

-RP

[sandiego89]

I will say the noise is most impressive, especially on take off. I have seen B's in the pattern and up pretty close for takeoff and landings. I could not distinguish any lift fan noise over the jet during the rolling landings I saw. The barn door over the lift fan surely looks like it shoud rip off. Must be a robust hinge.

[glad rag]

yVlmoNtcyhY

[CoffmanStarter]

If it looks right, it flies right!

Absobl00dylutely ...

Spitfire ... EE Lightning ... TSR2 ... Chipmunk ... IRMC :ok:

As for this LM F-35 thing that looks like a pregnant monkeypea ... no chance ... :sad:

#FunctionOverForm :=

[Darren_P]

The guy doing the F-35 commentary talks about "extreme agility" at 1:30.....

[Fatnfast]

What an absolute pigs ar5e of an aircraft. They should put this thing out of its misery. If that`s all it can manage after endless hours of modelling, simulation and thousands of flying hours; then there`s no hope.

[longer ron]

They could always do a ski jump demonstration !............

Oh wait :rolleyes:

[SpazSinbad]

UK F-35B STO Short Take Off

https://www.youtube.com/watch?v=wC5J2SxTgZk

[BEagle]

Clever, but still as ugly as sin....

[Courtney Mil]

To someone that understands something of the complexity of what's going on in that take-off it's all very clever. But to a layman it looks like it just about staggers into the air. The punters will be asking why it can't do what the Harrier does - or in the UK "did".

[longer ron]

Very clever ... but still not a ski jump ; )

[cuefaye]

But we're not saying the Harrier's/was pretty are we!

[ZeBedie]

Paris Air Show 2013 - Su-35 vertical take-off + Air Show

Wow - an impressive demonstration of the impossible!

[ZeBedie]

But we're not saying the Harrier's/was pretty are we!

Compared to the F35 it is.

[Sun Who]

Hmmm, so many doors, hinges, swivelly bits - all having to work together, every time, without fail...

As one particular 'engineer' might say: "The more they overthink the plumbing, the easier it is to stop up the drain." Mechanically more complicated than a Chinook - or any helicopter for that matter?

Sun.

[Willard Whyte]

Don't trust choppers either. Although at least they don't try to surprise the gods of lift to the tune of ~89 kilonewtons in a split second.

However, I won't be flying either so from that point of view I'm bloody ecstatic. As a taxpayer I'm fed up with crapping money in to the lost causes in which the tossers in mod wish to get directorships.




But we're not saying the Harrier's/was pretty are we!


Compared to the F35 it is.

Oh come on, the Harrier's big-eared intakes make it look like a Norfolk farmer's daughter (or wife, as they are otherwise known).

Mind you, both are a bit like a fat bird or a moped*: wouldn't be seen riding either in public.


*did actually rent a moped in Canada a few years back. Bloody good laugh, thankfully no photographic proof. Excellent det. all round: cock all flying; many, many steaks and bottles of red. Also, during the Langley air show, managed to offload a popcorn eating freak on to the sqn boss: he took one for the team there!

[Courtney Mil]

Like, WW.


:ok:

[burnden]

Got up close to the mock-up at the recent Singapore Air Show, and it is one ugly looking jet !!
Isn't there some rule that if it doesn't look so good, it probably won't fly so good? If there isn't, there should be with that monstrosity!
The F-4 may have been double-ugly but it looked like it was meant to do a mean job. That thing looks like a childs' toy jet - but fatter !
PS. I didn't like it.

[longer ron]

I have had a couple of pm's asking about my 'ski jump' comments !
I only mentioned the ski jump because although ski jumping is crucial to operating from our 'F35b' carriers and as we are now some years into F35b test flying ...

AFAIK - no F35b has actually done a 'ski jump' take off yet !
The last time I saw a photo of the trials ski jump installation it was going rusty and was surrounded by weeds etc !

unless anybody knows any better ????

[SpazSinbad]

JumpDeSki tests due this year at NAS Patuxent River - have not heard/read more than that though. GoogieErf Image 20 Oct 2013

http://i98.photobucket.com/albums/l261/SpazSinbad/NewerAlbum/NASpatuxentRiverGoogleZOOMskiJumpONLY20oct2013.gif~original (http://s98.photobucket.com/user/SpazSinbad/media/NewerAlbum/NASpatuxentRiverGoogleZOOMskiJumpONLY20oct2013.gif.html)

[XR219]

If you think the F-35 is ugly, then be thankful Boeing didn't win the JSF competition....

http://upload.wikimedia.org/wikipedia/commons/thumb/3/39/USAF_X32B_250.jpg/320px-USAF_X32B_250.jpg

:eek:

[LowObservable]

XR219 - This may point to an important rule:

When all responses to an RFP are ugly, it's probably a requirement problem.

See...

The Fleet Shadowers
AMST (YC-14/15)
LARA (if you think the OV-10's ugly, you should see some of the losers)
US Army Request for Data R40-C (XP-54/55/56)

... and so on.

[Vzlet]

No disagreement that the X-32 suffers a certain lack of attractiveness. If, however, the upper half of the plane were separated from the slab-sided canoe of the lower fuselage, its appearance would be considerably improved. I think the top half of the plane resembles another Boeing product, the Bird of Prey.

https://farm8.staticflickr.com/7001/13927515996_a378c95799_c.jpg (https://flic.kr/p/ndJah9)Boeing X-32B (https://flic.kr/p/ndJah9) by Vzlet (https://www.flickr.com/people/15086926@N08/), on Flickr

http://www.pprune.org/<a href=&quot;<a href=https://www.flickr.com/photos/vzlet/13927515996&quot; target=_blank>https://www.flickr.com/photos/vzlet/13927515996&quot;</a> title=&quot;Boeing X-32B by Mark Carlisle, on Flickr&quot;><img src=&quot;<a href=https://farm8.staticflickr.com/7001/13927515996_a378c95799_c.jpg&quot; target=_blank>https://farm8.staticflickr.com/7001/13927515996_a378c95799_c.jpg&quot;</a> width=&quot;800&quot; height=&quot;534&quot; alt=&quot;Boeing X-32B&quot;></a>

[Courtney Mil]

I may have missed your point, but the top of that does not remind me of any bird of prey I've ever seen flying and certainly not MD's aircraft named for a raptor that I flew. Unless you mean a jumping bean with two tails...

[WhiteOvies]

There's no ski jump left in the UK except Lusty anyway. The one at Pax will get its chance eventually! Fact: it was designed and built by a UK company (based in Stockport as I recall) so another benefit to the UK of the F-35 program! ;-)

Pax River museum has the X-32 and X-35 parked opposite each other and the X-35 definitely 'looks right' in comparison. Having literally crawled all over the X-32 several times I struggled to find any angle in which it looked good.

I also attended an RAES lecture from Paul Stone, the RN X-32 test pilot, which also gave several technical reasons why the X-32 lost the competition, along with some good dits!

[Courtney Mil]

Isn't that a bit like stating which was the least ugly woman you every admired after several beers?

[Vzlet]

These may help clarify my point:
http://i.kinja-img.com/gawker-media/image/upload/s--AHOJEvhT--/c_fit,fl_progressive,w_636/19gwmkibfw1xbjpg.jpg


https://farm8.staticflickr.com/7027/13950613605_ae989655a2.jpg

[D120A]

As the F-35, by virtue (sic) of its design, carries around with it tons of ironmongery and coupling shaftery which it needs for only 2% of its flight time, will it be demonstrated at Farnborough amongst the fighters, or the freighters?

Entry requirements this year on Trade Days should be two-fold: the possession of a valid ticket, and the wearing of a Pegasus tie. :ok:

[WhiteOvies]

Courtney, you are not wrong but I can assure you they were all gorgeous in Centrals, every single one of them! :}

[longer ron]

There's no ski jump left in the UK except Lusty anyway.

Somewhat missing my point ; )

Ski Jumping is crucial to the UK F 35b operation,they are certainly taken their time giving it a go LOL ; )

[WhiteOvies]

Not entirely ;-)

It got pulled from the test programme when the UK switched to the C variant and now has to get shoe-horned back in. The modelling has been done and it's been done in the Sim at Warton. The ramp is ready and waiting at Pax but with sea trials on HMS Queen Elizabeth a few years away yet there's no rush.

I'm sure it will be all over the internet when it happens!

[longer ron]

'Shoe Horned' back in is a lovely statement WO :)
Some of what you say may be true but :)

[hoodie]

Is it just me that fails to see any similarity at all between X-32 and Bird of Prey?

[Engines]

LR,

What White Ovies said IS true, not 'May be true'.

F-35B has a firm requirement to be able to carry out a ski jump launch. As a result it's been designed to do that. The Pax ramp has been built and will be used to verify and establish the performance off a jump. Which will be a lot better than off a flat deck STO.

Any questions on that?

Best regards as ever to those doing the work to make things work

Engines

[longer ron]

Sorry - bad english on my part !

There is almost always more to any story ! :)

It must be one of the most critical test points left,and it is slightly different to a Harrier ski jump in that STOVL mode is not used,after all - one wouldn't want the 'bin lid' sticking out - would one ?

rgds LR

[LowObservable]

LR - Attempting a ski-jump without the "bin lid" (or '57 Chevy hood, as it is known in these parts) open would be rapidly followed by a landing in the style of that great "Lockheed Martin legacy" product, the F2Y Sea Dart.

The drag factor from the bin lid may not be as scary as it looks. With the 20 megawatt garbage disposal on full blast, the airflow in that region is going anywhere but straight aft.

[longer ron]

Just checking chaps - some dodgy ex navy guy told me it was going to be launched with the bin lid shut ... after all the russkies do it :)

[LowObservable]

Was it S*****y W**d?

The Russky aircraft in question have respectably sized wings, not sawn-off penguin-like appendages bolted to the side of a brick-like body.

[Engines]

LR and others,

Perhaps this post might help sort out fact from invective on ski jump stuff.

Ski jumps can be used by both conventional and powered lift (STOVL) aircraft. In both cases, they launch the aircraft into the air below its normal takeoff speed, and the aircraft then spends a period of time in a reducing rate of climb while it accelerates to full wing borne flight, and then climbs away. It's been described to me as a 'runway in the sky'.

However, the two types get very different levels of advantage.

A conventional aircraft (e.g. Flanker, or Fulcrum as used by Chinese and Russia) cannot be launched below normal takeoff speed at max gross TO weight (MGTOW), as the only way they can maintain a safe minimum rate of climb is to adopt a high angle of attack and use engine thrust as best they can. That creates more drag, which delays acceleration, which means lower rate of climb away from the sea. This is why you don't see these aircraft launch with many external stores, and it helps explain an unusually public complaint by a Chinese Navy Admiral over the poor performance of his aircraft.

Conventional ski jumps aren't new, but have usually been discarded due to the inherent limitations I've summarised above.

A STOVL aircraft can launch at much higher relative weights, because it can vector its thrust to the optimum angle to support the aircraft by a combination of wing lift and powered lift so as to deliver the required acceleration and climb out. The angle will be scheduled after launch to move aft as wing lift builds. (Of note, the UK sets a minimum 400 fpm rate of climb as the limiting performance measure for ski jump launches).

Ski jump launch is an extremely effective system for maritime STOVL aircraft, is low workload and safe, as the pilot is guaranteed to be climbing away from the sea, and has more time to react in the event of an engine failure. It also delivers a large improvement in launch weight compared with a flat deck STO.

Oh, and the ski jump was a Royal Navy invention. And the F-35B lift system integration and flight controls design was led by some amazingly talented Brits. And Brits are leading the STOVL flight testing.

I know that there are plenty of folks here who disparage the STOVL variant, and it's technology. It's a free forum, and they can do so as much as they like. But it's a shame that it sometimes prevents very smart and hard working people getting the credit they deserve. Perhaps this post will help restore a bit of balance.

Best regards as ever to all those doing the hard work and bashing out the hard miles

Engines

[sandiego89]

There's no ski jump left in the UK except Lusty anyway

Really Whiteovies? Happy to be corrected but I believe the jumps at Yeovilton and Wittering are still in place. A quick search of google and bing map overhead views still shows them there, but I am not sure of the date of the pictures. Were they torn down?

[LowObservable]

Engines is correct. Ski-jump is synergistic with STOVL - partly because of powered lift and partly because a STOVL aircraft has not only lift, but also control below its wingborne flying speed.

But to get back to the "bin lid" point: A Harrier-type STO has a certain elegance in that you start the roll with 100 per cent thrust straight aft and can then quickly and smoothly dial in any amount of vectoring. The F-35 is a bit more restrictive in that the aft nozzle is delivering part thrust for acceleration (because the lift fan and roll posts are active), the lift fan vectors to 45 deg only and the roll posts (9000 lb thrust) do not vector aft at all.

Luckily the F135 is a :mad:ing big engine...

[SpazSinbad]

Thanks again 'Engines' your point about "...And the F-35B lift system integration and flight controls design was led by some amazingly talented Brits...." always amazes me how all this innovation by youse Brits is not acknowledged here. I guess this is not a British forum eh. Just crabs scuttling about. :}

[Engines]

Guys,

Just thought it might be helpful if I made a further post on this STOVL ski jump stuff.

LO is quite right in that the powered lift system on the F-35B can't vector all the thrust aft like the Harrier does. That's part of the trade off in getting your main propulsion engine located at the rear of the aircraft, where it really belongs for a fighter/strike type aircraft.

The lift fan can vector aft to around 50 degrees: on the X-35 there was a sort of 'pram hood' device that gave further aft vectoring - however, this was replaced in development by a much lighter 'vane box' device (UK designed) which still gave enough aft vector to meet the requirements. These were a set distance for a flat deck STO, and another shorter distance for a ski jump launch. The launch weight was driven by a defined operational scenario. J

The roll posts deliver around 2000 pounds thrust each in balanced operation, but they are turned off during the STO run and switched back on just before launch. This facility was suggested by a very talented RN FAA air engineer, and gratefully adopted during the weight saving programme. Another excellent Brit contribution.

The point overall is that the F-35B meets all its STO requirements, as well as its short landing targets. And it's a much heftier bird than the Harrier - over 55000 pounds off the ramp.

Happy to keep this sort of stuff coming as long as it helps. Do let.me know when I start boring people.

Best regards as ever to young and talented navy aircraft engineers

Engines

[PhilipG]

Is a ski jump a ski jump or for optimal launch weight at a standard wind over deck and pressure, is the geometry different for a Harrier and an F35?

I suppose the subsidiary question is there a plan to build an appropriate ski jump at Marham?

[WhiteOvies]

San Diego,

Yeovilton's has certainly gone but I may be wrong about Wittering, I've not been there for a few years. Unfortunately I'm not based in that part of the Country these days.

Something Engines hasn't mentioned in his excellent posts is that because of the UKs involvement in F-35B the flight control software has always been written with a ski-jump take-off in mind. It is not something to be newly coded and loaded into the aircraft.

Geometry is no different for the new carriers in that a 12 degree ramp was fitted to CVS and is fitted to Queen Elizabeth. The difference is that the QE ski jump is longer and less abrupt.

Not sure about putting one at Marham. I think some people are still struggling to think of 617 Sqn having to go to sea :p

[O-P]

Engines,

I presume that the lift-fan stays static and the vanes move to direct the thrust? Can the vanes go past 90 deg and act as a brake?

[longer ron]

I am certainly not taking a swipe at the extremely talented brits slaving away on the F35b although I might be a little jealous of their salary :)

I do know some of them :)

The trouble is - the whole thing is being done kind of ar5e about face,the carrier is in build and can only be built with a ski jump now (no possibility of cats and traps) and yet the a/c still has not completed a land based ski jump take off !
Just seems a dumb way of going about things LOL It is usually more sensible to trial things before committing to production !

I am never taking a swipe at our engineers/pilots btw - we always have to cope with the mess left by politicians and top management.

Thanks for the info Engines,much appreciated and I hope you understand that I am not taking a swipe at the people involved - just the concept and the unfortunate way that it has all panned out.

rgds LR

[Engines]

LR and others

Yes, the lift fan is fixed and the vane box can deflect the thrust forward of the vertical. Used to help decelerate the aircraft to the hover as well as other things.

LR, in truth the programme isn't doing things 'ar5e about face' nor are things being done in a 'dumb' way.

The ship and the aircraft have proceeded side by side for many years now. At meetings in 2003, the CVF team were demanding a ski jump profile from LM. That profile wasn't available then, but was provided around 2006/7 once the F-35 team had done enough sim work on ski jumps with mature flight control models.

The thing to grasp is that ski jump ops are a low risk area of the F-35B programme. Ski jump launch is not as 'dynamic' as a flat deck STO, and in some areas the F-35B offers less challenges than the Harrier.

What was definitely 'dumb', in my view ( others can disagree) was the UK MoD's two year game of 'F-35 variant hokey-cokey'. Swapping from B to C and back again disrupted the STOVL test programme and, I think, made the UK look less than professional.

The fact is that the programme is where it is, and many people are working hard and cleverly to make it a success. Lots of them are Brits, who find it a little difficult to understand why so many people spend so much time and effort talking the project down.

It's a free country, and a free forum, as I've said many times. Post whatever you like. Just make it accurate and factual.

Best regards to absolutely everyone

Engines

[longer ron]

What was definitely 'dumb', in my view ( others can disagree) was the UK MoD's two year game of 'F-35 variant hokey-cokey'. Swapping from B to C and back again disrupted the STOVL test programme and, I think, made the UK look less than professional.

I would not disagree too much with that statement except it must be remembered that the carriers had been 'sold' to us as completeable (new word :)) as either a ski jump carrier or a conventional carrier with cats n traps but of course the reality was a little more er complicated than that...it usually is when wastospace and politicians are involved !

The thing to grasp is that ski jump ops are a low risk area of the F-35B programme

Glad to hear it - wouldnt be surprised if somebody had said that about the tailhook on the 'C' ; )

rgds LR

[Hangarshuffle]

1.Put it on static display (as a minimum) at both RN Air Stations when they have their Air Days (if they still are or do). That alone will put thousands on the attendance (and money in someone's pocket needy pocket other than....
2. You've got to sell this hard. The public are becoming jittery about the UK defences overall military ability. They need to see something positive that is being bought in their name for their defence.
3. Need to back this up with the public to see and meet the people who will be flying, maintaining and operating this aircraft. Show off the best young Naval people.
4. Spin it, spin it and spin it.


And if you have any balls... invite the Russians over to the same party and let them show off their latest hardware.
* If its too late to do this this year then do it next year, but do something.

[Haraka]

invite the Russians over to the same party and let them show off their latest hardware.

Perhaps not, since it will give an opportunity for the daft old story of it being conceptually a Yak-141 (FREESTYLE) knock-off being dredged up yet again......

[GreenKnight121]

the carriers had been 'sold' to us as completeable (new word :)) as either a ski jump carrier or a conventional carrier with cats n traps but of course the reality was a little more er complicated than that...it usually is when wastospace and politicians are involved !

EVERYTHING I saw in the run-up to the "main gate" decision on 25th July 2007 to go ahead with the CVF program said "to be built as STOVL with a ski jump, but convertible as part of their mid-life refit to catapult & trap operation".


I never once saw anything from the UK government or BAE that either said or implied that the switch was supposed to be possible during construction, until the 2010 SDSR came out.


Could you point us to where it was said otherwise before the 2010 SDSR?

[Whitewhale83]

If memory serves the 'convertible' carrier was the original 300m and then 290m designs. The government then insisted on more budget cuts and forced a redesign to a smaller version, they then realised that that smaller craft had a poor sortie rate so forced another redesign up to the current 280m version. Along the way the ability to change launch systems was dropped which the government OK'd as it saved a few pennies.

So in brief, various governments introduced years of delays and cost increases due to constant re-design and engineering work while going about trying to save money in some of the most stupid ways possible.

At the height of the nonsense when the press and public was questioning what was going on the government of the day conviently forget it was them who changed the design brief and agreed to the dropping of various features.

[lmgaylard]

Sandiego89;


The 'Ramp' at Yeovilton was dismantled not long after the Sea Harrier was decommissioned. The run-up is still there, as is the 'pit' but the actual ramp itself has gone.
I can't say for definite but I think the Wittering ramp has also gone.




A couple of years back I attended a RAeS lecture by Doug Taylor ( ski-jump creator) and he said that the US tested virtually all their fast-jet aircraft at that time on the Ski-Jump.
He showed some slides of various aircraft 'jumping' and, from memory, included A-4 Skyhawk, F-5 Freedom Fighter and, I think, an F-4 Phantom.
I believe the trials were successful at the time.


I never could understand why the US Marines never fitted a 'Jump' to their ships. I'm told that whenever the USMC cross-decked to one of our carriers they spoke very highly of the Ski-Jump.

[skydiver69]

There is still one ramp in existence in the British inventory http://en.wikipedia.org/wiki/HMS_Illustrious_(R06) :D

[Madbob]

Correct me if I am wrong, but I seem to remember a fairly critical limit speed when "hitting" the ramp (this was a 12 degree model) that was due to nose wheel strength limitations with the Harrier.

I wonder if the F35 (B) will be similarly limited or whether the nose gear is sufficiently strong for this not to be a problem. Maybe with a longer deck (on the QE2 class) the transition from flat-deck to ramp incline will be more gradual for this not to be an issue.

A 55,000 lbs T/O mass is quite a big increase for the F35 from the Harrier II (which itself was a lot heavier than the GR3/Sea Harrier) and only 3-5,000 lbs less than the max weights allowed for the F4 and Buccaneer which ISTR were 58,000 and 60,000 lbs respectively.

Just curious.....

MB

[Not_a_boffin]

If memory serves the 'convertible' carrier was the original 300m and then 290m designs. The government then insisted on more budget cuts and forced a redesign to a smaller version, they then realised that that smaller craft had a poor sortie rate so forced another redesign up to the current 280m version. Along the way the ability to change launch systems was dropped which the government OK'd as it saved a few pennies.

So in brief, various governments introduced years of delays and cost increases due to constant re-design and engineering work while going about trying to save money in some of the most stupid ways possible.

At the height of the nonsense when the press and public was questioning what was going on the government of the day conviently forget it was them who changed the design brief and agreed to the dropping of various features.

Not quite.

The current design (design Delta) remains perfectly capable of being converted to catapult & arrester gear configuration. The general arrangement drawings for the ship show the space allocation for the systems quite clearly and you can see the spaces if you walk round the actual ship.

The problem is that once the arrangement drawings had been completed in 2004, no further detailed work on the CV design was contracted for, although the overall design config control was maintained. Essentially, while the design is capable of being converted, no-one asked the Alliance to actually progress the detail of that design (ie produce the detailed system and component level design information to allow people to actually produce the equipment items and install them on the ship). Part of that was reluctance (by the US) to release EMALS info to some degree because at that stage it didn't exist and also our favourite FLA - ITAR. But mainly because both RN and RAF were still treating the CV option as a potential fall-back rather than a serious option.

What that meant, was that when the CV-reversion was requested, production of the required design information would have meant either stopping work on the second ship and waiting for design info (while paying for the workforce, courtesy of TOBA) or progressing the ship but then tearing chunks of it out again to fit EMALS/EAR. That is why the projected cost is so high, when a rational look at the work content just to include those systems in the ship would never get anywhere near the £1.8Bn figure quoted.

So no design features were dropped, it's just that the MoD did not fund the detailed elements of the design process that would have allowed the ships to complete as CV-capable at an acceptable price. primarily a commercial / programme issue rather than technical.

[LowObservable]

Thanks, Mr Boffin.

Engines - Interesting note on the roll posts - I'm not sure that has been out before (and checking, it was not in a quite detailed brief from early 2009).

Haraka - Of course it's not a Yak-141 Freestyle knock-off. I mean, the 141 could not do a VL demo at Farnborough without damaging the runway :E. Conversely, one also remembers when lift-plus-lift/cruise was dismissed as old hat, and doubtless far heavier than the bold new shaft-drive technology.

[Eminence Gris]

Wonder if they've applied for the ITAR to bring it to UK, usually takes a year or two!

EG

[Courtney Mil]

It's my understanding that ITAR applies to export, not visits, displays, etc. Of course, there will already be technology transfer agreements in pace for certain nations under FMS or partnership agreements. My understanding, anyway.

[Engines]

Madbob,

Good question on the ski jump landing gear loads - perhaps I can help.

The landing gear layouts on the Harrier and the F-35 are fundamentally different, especially in the nose leg area. The Harrier has a 1950s style 'bicycle' or 'tandem' layout, and the weight of the aircraft is split almost 50/50 between the aft leg (we called the 'main') and the forward leg (which we called the 'nose leg').

What this meant for Harrier ski jump ops was that the front leg was fairly heavily loaded. We increased the liquid spring pressure for ski jump ops, and the limiting condition was to avoid total closure of the nose leg spring as it reached the end of the ski jump. (The leg started closing as it entered the ramp, and closed steadily as it approached the exit lip).

The F-35 has a more conventional 'tricycle' layout, with the two main gears taking around 90% of the load, the nose leg taking around 10%. The early checks on ski jump profiles and predicted launch speeds showed that the nose leg loads during ski jump launches were well within the highest design load, which was driven (I think) by vertical landings, with an arrival on the nose leg as the worst case, or with high lateral drift. the forthcoming tests at Pax will provide the real data.

LO's point about lift plus lift/cruise options for STOVL aircraft points to a key aspect of the JSF/F-35 project. The basic physics of powerplant technology have driven the choices available to the teams who were required to produce a large single engined single seat aircraft. (As I've posted a few times, the single engine requirement was a key driver set by US DoD staffs who wanted to avoid the weight and cost overruns associated with a slew of failed US twin engined projects in the 70s and 80s).

In the end, the Harrier concept (a large engine in the middle of the aircraft providing both lift and cruise via vectoring arrangements) just couldn't be taken forward to meet the JSF requirements. There wasn't enough lift at a reasonable weight from hot jets, and the hot gas ingestion problems were insurmountable. Lastly, having an engine in the middle of the aircraft just couldn't be reconciled with an effective supersonic strike/fighter aircraft. Kingston battled to produce a workable design all through the 70s and the 80s, and Boeing's X-32 proved the point.

The LM solution was built around a separate lift device located forward using cold air to deliver thrust as efficiently as possible, which also offered a solution to the hot gas ingestion problem. This allowed optimal location of the main engine at the rear. A number of options for driving the lift fan had been tested between the 60s and the 90s (including gas drive, and even electrical), but in the end, shaft drive offered the lightest and lowest volume solution.

As I've often posted, it's good that people question and criticise the F-35 programme. I hope that my posts help them understand the basic physics behind the issues and also to understand just how challenging the choices are that have to be made early on in a combat aircraft programme.

Best regards as ever to all those making the hard calls out there now,

Engines

[LowObservable]

One has to wonder whether the shaft-driven (SDLF) system ended up saving any weight or money versus the separate lift engine (LPLC).

SDLF eliminates a (small) turbine gas generator but adds a shaft, gear and clutch. It also drives weight into the main engine (bigger LPT and shaft) where LPLC does not, and it tends to push you towards a shorter (hence fatter) body because you want to constrain shaft weight, volume and number of bearings. I should think that digital engine controls would still allow you to use differential throttle for pitch control in hover.

The Macs proposal was LPLC, of course, but there was substantial prejudice against that solution and there were other aspects of that offering that weighed against the team. (They had come together rather late in the game.)

It's all spilled milk of course - about 12 billion gallons or about 90 loads on this:
http://maritime-connector.com/images/tieurope-16-wiki-18628.jpg

[Engines]

LO (and others)

The main issues, in my view, with a separate lift engine were these:

1. A separate jet lift engine had to use hot air to develop thrust - that's inherently less efficient than using cold air. That reduces the basic efficiency (and weight) advantage of a separate engine.

2. A hot engine exhaust located towards the front of the aircraft will inevitably introduce hot gas ingestion effects. As LM have shown, the cold lift fan provides a useful way of helping get past a very serious problem.

Having looked at a couple of papers recently, it looks as if the Gas Coupled Lift Fan (GCLF) was a very serious contender within NG/BAE until late in the day, when it became clear that the piping and ducting required to drive a large (c. 18,000 lb thrust) fan would place too much volume demand on the fuselage design. LM appear to have gone fro shaft drive from early on.

As I've said before, the designers have to make some very big calls early on for powered lift aircraft. In my view, LM got most of them right, given the requirements they had to meet. Others are happily invited to disagree.

Best Regards as ever to those working the sums,

Engines

[Courtney Mil]

Wasn't this the thread about F-35 going to display in the UK this year? I don't suppose it's coming to France, is it?

[glad rag]

Nice one courts, happy days to ya.

:ok:

[Bevo]

For those interested in how LM was able to win the JSF program, please look at the history of the Advanced Short Take-Off/Vertical Landing (ASTOVL) program.

McDonnell –Douglas had the top two (ASTOVL) proposals (one for gas-coupled lift fan and one for shaft-coupled lift fan). DARPA told McDonnell to move forward with the gas-coupled lift fan using the GE YF120 engine (which later was developed into the General Electric/Rolls-Royce F136). DARPA then funded LM to work on the shaft-coupled design using the P&W F119 engine (which was developed into the P&W F136). McDonnell actually built a full-scale design to house and test a gas-coupled lift fan when the program was terminated and the JSF program was started.

While McDonnell was developing its proposal for the JSF program, it was told that the decision had been made to use the P&W engine and that McDonnell would have to include the cost of developing the GE YF120 engine into their program cost estimate. At that point there was little time to do anything except bring Northrop on board with a separate lift engine.

So that is also the story of how DARPA eventually caused the demise of McDonnell Douglas, forcing it to merge with Boeing.

(Sorry Courtney, but since it was brought up…..)

[LowObservable]

Bevo - That's interesting. The story from Paul Bevilaqua is that the SDLF evolved from tandem-fan ideas (not unlike the way that the Harrier evolved from the Wibault Gyroptere) at Lockheed Skunk Works. At the point where I became cognizant of the whole remote-drive fan idea (1991ish) it did already seem that Macs and GE were teamed on the GDLF.

However, it's also quite possible that such teaming was directed from on high.

Engines: I don't know that either system (LPLC or SDLF) is inherently more efficient than the other one. It depends on the BPR of the lift engine (which appears to be lost in the mists of time as far as the GEA-FXL design goes). Of course lower BPR=hotter, but it also means lower diameter and a more slender front end. Then again, it allows the back end to run cooler (mixed flow).