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F-35 Cancelled, then what ?

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F-35 Cancelled, then what ?

Old 11th Dec 2014, 16:24
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I'm sure that the Luke public affairs staff won't find any hot-fuel issues to write about in their new assignment:

Peterson Air Force Base - 821st Air Base Group
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Old 11th Dec 2014, 16:36
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So if the temperature of loaded fuel is not a special issue for the F-35, and the USAF has been loading fuel from green tankers in very hot climates quite routinely for the last 25 years ago, why did the Luke people even think that there was a problem? What did they see, or experience, that they thought was an issue? Did they make the whole thing up so they could wrap a press release around it?

BD also misses the fact that this is not a new issue:

http://www.gao.gov/new.items/d09303.pdf (p.26)

It was supposedly solved with a new fuel pump in LRIP 3.

Anyway - anyone want to bet that further enquiries to Luke PA will be referred directly to Mr Vo-De-o-Do in JSFPO?
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Old 11th Dec 2014, 18:58
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Could there be any stealth related uses for fuel as a heat sink? I imagine nobody would tell me if there was anyhow so I don't expect an answer....:-)

Imagining for a moment that it was possible then I suppose this would make it desirable to have fuel as cool as possible and thus provide the longest possible period of "protection". e.g. a brief "cool off" at just the right moment combined with flares - could one use that to escape a missile more reliably?

I know, nonsense.
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Old 11th Dec 2014, 19:04
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We've been using fuel as a heat sink for decades. You could overheat the F3 on the ground if you tried. This story may not be such a big deal. Permanent shelters for the bowsers may be the answer. Too early to jump to conclusions. Maybe.
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Old 11th Dec 2014, 22:34
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New Flight Global article re F-35A for Canada

http://http://www.flightglobal.com/n...ssions-407025/

Interesting little article suggesting that Canada's evaluation of F-35A against Super Hornet, Rafale and Typhoon saw no overall notable victor over a range of missions out to 2030.

Another potential customer seeking a Plan B?
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Old 12th Dec 2014, 02:07
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Originally Posted by GreenKnight121
A lab test imposing temperatures in excess of 130 degrees was just completed “and the aircraft performed exceptionally well..."
The aircraft 'performed exceptionally well'....in a laboratory test?

I'm ok with accurate propaganda to let the taxpayer know that the money is being spent well....if the team has completed deck landing trials etc well then absolutely be proud and let the world know. But I get nervous when they start looking for positive news to fill the pages and they have to resort to something like 'lab tests'.

"F-35 Meets Another Milestone

The F-35 program has met another milestone on its way to operational acceptance today when a spokesman announced another series of tests had been successfully 'signed off'.

The tests, conducted at various AFB over an 8 month timeframe, were conducted to determine the optimum nose-wheel tyre pressurisation.

"The Aircraft performed magnificently over a broad range of temperatures and tyre pressures" a member of the test team said. "The nose-wheel was subjected to lab tests simulating a temperature variation of up to 15 degrees and pressure fluctuations of up to 5 PSI. Simulated landings in a variety of landing configurations were successfully completed."

"This is a red-letter day for the F-35 Program." LTCOL Amanda Huginkiss, Test Team Coordinator said."
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Old 12th Dec 2014, 11:21
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My understanding is that IR signature considerations make any direct air cooling, or heat exchangers venting overboard, problematic. The approach taken is to dump all heat into the fuel and thence into the primary exhaust, which is managed and mixed-flow in cruise. The heat either goes out as fuel is burned or goes through an HX in the inlet duct - that HX is fed through a small inlet above the right main inlet.

The heat sources include the cockpit and avionics ECS and the flight controls - AFAIK the aero loads on the controls are opposed by the electrohydraulic actuators, and that generates heat (whereas a pure hydraulic system is more thermally balanced). Correct me if I am wrong, Engines.

Under certain circumstances more heat is generated than can be got rid of and the fuel gets hot, and will eventually hit limits. (There was some work done on heat-tolerant fuels some years ago, but the F-35 has to use regular JP-5 or JP-8.) This could mean that you'd have to go into a less demanding part of the envelope to cool off, or retain some part of the fuel load.

Clearly though the heat capacity of the fuel is affected by how hot it is when you load it. Fuel chillers were used for early flight tests. The new fuel pump was more efficient (=added less heat to the gas) but apparently the Luke folks were seeing an issue, came up with a cheap mitigation and went public with it.

By the way, it would not necessarily mean cancelling sorties, so that's a potential misdirection. One obvious mitigation would be to launch with part fuel and then top off from a tanker that's been chilling at FL250 for a while.
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Old 12th Dec 2014, 12:02
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Or just keep the bowsers in the shade. My understanding is this is a ground running issue. Plenty of cooling air in flight.
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Old 12th Dec 2014, 13:54
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There is plenty of cooling air available in flight, but only one place it gets in - the scoop just above the RH inlet.



That feeds a heat exchanger that exhausts its warm air into the inlet duct (or the fan duct).

Result, I believe, is that this is more than a ground-running issue. More here:

AFRL?s Invent Program Tackles Aircraft System Efficiency | AWIN content from Aviation Week

And here:

https://www.ieeeusa.org/calendar/con...rview-Iden.pdf
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Old 12th Dec 2014, 16:11
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Sounds like the stat is either failed or wrong spec........
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Old 12th Dec 2014, 16:46
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LO,

Happy to help.

Both IR and LO signature considerations make thermal management (TM) on modern aircraft more of a challenge. IR because you don't want hot exhausts showing up, and LO because scoops and vents can compromise RF signature. TM was identified as a major risk early on in the F-35 programme, and has been worked hard since.

F-35 has gained additional cooling scoops under the wings, and additional exhaust vents on the F-35B at least. Electric flight controls do add heat loads, hydraulic systems get rid of much waste heat through their fluid reservoirs, but at the cost of weight and space.

Your description of the way F-35 manages heat is close. It also uses liquid cooling circuits to manage the heat of certain systems. I can't give more details as it's been too long since I worked the TM issues. But broadly, you're on the button. You are quite correct in that AAR is a great way to get some cool fuel on board. Remember that the F-35 has a quite novel Integrated Power Pack (IPP) architecture that powers cooling functions instead of separate cooling systems as in legacy aircraft.

For Hempy - the 'lab test' they are referring to was very probably the whole aircraft 'environmental test' that has to be carried out in a specialist test facility, the 'lab' they were referring to. It will be backed up extensive test flying, but in this case, a lab test is a must.

Bottom line (as far as I remember) was that the aircraft systems were handling TM in all but a limited number of potential 'corners' of the envelope. The issues facing F-35 are pretty much the same as were faced by F-22 and B-2. As I remember, TM problems afflicted the AEW Nimrod, and affect a number of current aircraft out there now.

Hope this helps

Best Regards as ever to those crunching the numbers,

Engines
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Old 12th Dec 2014, 20:46
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Forgot the wing scoops. Thanks!
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Old 12th Dec 2014, 22:00
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Nah...thought better of it...
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Old 15th Dec 2014, 14:44
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Espionage?

Perhaps we have another ingredient to add to the story? Espionage!

If we can add murder and a sex story- we have a complete saga for a television mini-series....

Chinese Engineer Facing Charges Of Stealing US Fighter F 35 Design Data

Chinese Engineer Facing Charges Of Stealing US Fighter F 35 Design Data - International Business Times
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Old 15th Dec 2014, 15:04
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No mention of UK getting any Base Maintenance Facilities...at all! Could this mean that Marham will boil down to only doing large component changes for the 16 jets on the UK books? (or could Lakenheath do them all?)

Italy, Turkey will lead F-35 maintenance in Europe - 12/11/2014 - Flight Global
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Old 15th Dec 2014, 16:36
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Rigga - This was not surprising, given Italy's massive investment and Turkey's labour costs. After all, one of the program's aims is to eliminate non-US combat aircraft prime contractors and related capability.

As for the espionage - customs found documents in his luggage? Wot? Everyone knows that you travel clean and put the docs on Dropbox. It's in Top 25 Things Every Spy Knows on Buzzfeed.
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Old 16th Dec 2014, 16:46
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Dutch F-35 orders ready to take off

As just reported on Flight Global

The Netherlands’ defence ministry has announced plans to order a first batch of eight operational Lockheed Martin F-35s, with the type to be delivered from 2019.

In an update published on 15 December, the defence ministry says it still plans to obtain a total of 37 F-35s, including five which will be employed as training assets. Initial operational capability with the Royal Netherlands Air Force is anticipated in 2021, with its planned full fleet to be available by 2024. The aircraft will be stationed at air bases in Leeuwarden and Volkel.

Lockheed has already delivered two conventional take-off and landing F-35As to the Netherlands in the USA, with the assets to be used during US-led initial operational test and evaluation of the Lightning II from 2015. According to its plan, the nation would receive eight aircraft per year between 2019 and 2022, with its final three examples to arrive in 2023.

The type’s introduction will coincide with a reduction in the nation's active fleet of Lockheed F-16s, from a current 61 examples to 45 in 2021 and 24 in 2023, before leaving use the following year.

Once at full strength, the Netherlands’ F-35 fleet will be sufficient for the nation to declare up to six of the type as available to support NATO operations, including two for quick reaction alert duties. Its investment in the type is expected to total €4.6 billion ($5.8 billion), the defence ministry says.
37 F-35s to replace 61 F-16s...
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Old 16th Dec 2014, 18:57
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Of which four will be available to OOA ops.
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Old 16th Dec 2014, 19:13
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The 85 JAS 39Es they were offered for the same money have to be looking good right now.
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Old 16th Dec 2014, 19:57
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Just a thought but maybe Luke has pre-LRIP 3 jets that haven't had the modified fuel pump yet? White paint is cheap and there's nothing wrong with local personnel having bright ideas to help. it's just the US equivalent of a GEMS award. Any excuse to have an uninformed swipe at the jet though...


The 'Lab Test' would be the full climatic lab at Eglin with a production spec test jet from Pax River. It's a very special hangar sized facility; the internet has great pictures of what it can do with F-117 and F-22. I haven't seen any public pictures of an F-35 in there yet.


Given the visual similarities of the Chinese J-31 to the F-35 is anyone even slightly surprised to hear the Chinese have been spying? They have a C-17 alike too. Also the manufacturer isn't going to write a press release saying that they've built a good aircraft, but not quite as good as the competition are they? The Chinese Airshow footage of the J-31 shows a few unstealthy elements to the design that I'm sure will be exploited if required.


Rigga, there are plans for infrastructure at Marham, but until it's built there's not a lot of point making a big song and dance about it. The assembly line in Italy is using parts made in the UK so it's not like UK industry is missing out.
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