F-35 External Fuel Tanks?

F-35 Armament, fuel tanks, internal and external hardpoints, loadouts, and other stores.
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spazsinbad

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Unread post01 Jan 2012, 03:45

Anyone know any recent developments on the external fuel tanks for the F-35 please? TIA There was mention in a recent Norway? Brief about developing them? No?

Contracts NAVY
April 28, 2006

"Lockheed Martin Corp., Lockheed Martin Aeronautics Co., Ft. Worth, Texas, is being awarded a $52,400,000 ceiling-priced modification to a previously awarded cost-plus-award-fee contract (N00019-02-C-3002) to exercise an option to certify the small diameter bomb for the U. S. Air Force Joint Strike Fighter conventional take off and landing (CTOL) aircraft and eliminate the effort for wind corrected munitions dispenser and external fuel tanks...."

Source: http://www.defense.gov/Contracts/Contra ... actID=3246


Israel to boost range of future F-35 fleet ? By Arie Egozi Washington DC[/b]
11 Jan 2008

"The Israeli air force wants to increase the operational range of its future fleet of 100 Lockheed Martin F-35 Joint Strike Fighters by adding new external fuel tanks that are already being developed by domestic companies.

Elbit Systems subsidiary Cyclone Aviation is offering to supply external tanks to be carried on the F-35's under-wing hardpoints, while Israel Aerospace Industries plans to produce conformal fuel tanks for the Israeli fighters.

Israel's air force recently completed the design of a unique F-35 version optimised for its mission requirements, but further details remain highly classified...."

Source: http://www.flightglobal.com/news/articl ... et-220748/
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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spazsinbad

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Unread post01 Jan 2012, 04:05

The internet can be a deadly shitestorm or really useful. Here is a turnup (at end of a very informative article about drop tanks):

Carrier-capable, all-composite external fuel tank
Legacy product positions builder for a shot at an F-35 contract.
Case Study From: High-Performance Composites May 2011, Michael R. LeGault 9 Posted on: May/2/2011

http://www.compositesworld.com/articles ... uel-tank(2)

Project-ready design capabilities...
"...Rashilla says GDATP’s next major design/manufacturing opportunity for an all-composite external fuel tank is likely to be the F-35 Lightning II. He expects an external tank will be built for the new jet at some point but reports that funding has yet to be approved. “The survivability requirements for the tank used in the carrier variant of the F-35 will be essentially the same,” Rashilla says. “We hope to be able to apply the lessons we learned on our F/A-18 tank design to that project.”

http://d2n4wb9orp1vta.cloudfront.net/re ... rawing.jpg
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GDallCompositeExternalFuelTankF-35perhaps.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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spazsinbad

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Unread post01 Jan 2012, 04:22

Then there is this chap's multicoloured text from AvWeek recent:

Israel reaffirms plans to take F-35 before USAF declares it operational Nov/28/2011

http://blog.daum.net/trent/8213146

"...Israel also postponed its requirement to add a 600-gal. external fuel tank...."
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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alloycowboy

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Unread post01 Jan 2012, 05:54

Just did a quick calculation and a pair of 426 gallon tanks gives following increase in range.

F=35A

31% (1572 nautical miles range drag neglected)


F=35B

43% (1287 nautical miles range drag neglected)


F-35C

29% (1 806 nautical miles range drag neglected)
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Unread post01 Jan 2012, 06:26

So their saying they may be able to manufacture external tanks with a low RCS? That would be great!
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elp

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Unread post01 Jan 2012, 08:07

A short history of external tanks with the F-35 program re: what would be qualified as stores at the end of SDD.

The original assumption is that they would use legacy F-18 tanks like the conventional shape shown above.

Once they got into simulation and later wind tunnel models doing stores separation they ran into problems. The conventional tank showed to be high risk for bumping into the aircraft and/or other stores.

So they came up with 3 elongated tear-drop designs. (see the graphic in the Sep 2006 brief). These carried a bit less fuel but were supposed to offer a solution. However in the same kinds of simulations there were still problems. There is a brief out there somewhere that shows quite the pitch-up of the tear-drop design coming way too close to the aircraft after being punched off. There were still risk issues of external store separation scenarios; for example when also carrying a 2000lb bomb on the nearby station. Of the three elongated tear-drop candidates the one that showed the most promise was one that had an extension on the pylon.

Eventually they decided that there was too much risk/time/money invested for now and pulled external tanks from SDD as per that April 2006 contract which also removed WCMD (for instance CBU-105). And of course that same contract added SDB for SDD.

Interesting about that April time line as they seem to have had no problem putting tear-drop external tank shapes in the Sep 2006 brief.

Also interesting is that the Norway briefs don't show the range advantage stated by AC above with the unproven external tank mission configuration.

Not long after; briefs started touting the idea that you don't need external tanks compared to legacy. :lol: I am sure that went to the plus side for MX calculations too as you don't need extra people/manhours to clean and maintain external tanks on a deployment if your jet can't carry them.

Maybe we will see them someday after SDD. Who knows? We do know that they have a heck of a lot more important problems to take care of than external tanks right now. Just not a priority.
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alloycowboy

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Unread post01 Jan 2012, 09:11

@ELP........ I think their is a lot of "top secret" stuff going on with the F-35 and external fuel carriage. For example lets say we need to fly a round trip from Jerusalem to Bushehr which is 826.16 nautical miles one way or 1652.32 nautical miles round trip. With a pair of 426 gallon tanks it is about 80 Nautical Miles out of reach for the F-35A. This probably why the Israelis requested the 600 gallon drop tanks that the F-22's are using.

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elp

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Unread post01 Jan 2012, 09:22

Unfortunately, "Top Secret" or what ever other classifications are used, doesn't allow one to ignore the laws of physics.

Don't know why you are showing the F-22. It has a whole different kind of aero performance. Tanks are cleared on the F-22 because they have done the work and there are existing operational procedures for it. And the obvious: it is in operational service.

So far, like a lot of things with the F-35 program, they are not there yet.

Maybe your FW friends can add some context to the points I already made. After all, the briefing came from their neck of the woods.
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spazsinbad

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Unread post01 Jan 2012, 10:52

Some old info - I think repeated on this forum elsewhere but regurgitated here nevertheless....

http://www.aiaa.org/pdf/inside/04_TC_Hi ... aa-apa.pdf (49Kb) 18 Nov 2004

"...Lockheed Martin Aeronautics conducted a trade study for the F-35 Joint Strike Fighter (JSF) aircraft to design the external fuel tank for improved performance, store separation, and flutter. CFD was used in conjunction with Sandia National Laboratories’ Dakota optimization code to determine the optimal shape of the tank that minimizes drag for maximum range and minimizes yawing moment for separation of adjacent stores. Data obtained at several wind tunnel facilities verified the predicted performance of the new aeroshaped, compartmented tank for separation and flutter, as well as acceptable characteristics for loads, stability, and control...."

Pic from same PDF says: "This wind tunnel model of F-35 features an optimized external fuel tank."
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F-35windTunnelModelExtFuelTankShape.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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Unread post01 Jan 2012, 11:10

@ spazsibad...... I wonder if they can squeeze in another 200 gallons of fuel into the F-35A airframe some where?
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popcorn

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Unread post01 Jan 2012, 11:31

alloycowboy wrote:Just did a quick calculation and a pair of 426 gallon tanks gives following increase in range.

F=35A

31% (1572 nautical miles range drag neglected)


F=35B

43% (1287 nautical miles range drag neglected)


F-35C

29% (1 806 nautical miles range drag neglected)


The CFTs on the F-16 have a capacity of 450 gallons each so something similar may be in the plans for the F-35down the road as a low-drag, low-RCS option.Hopefully this would not impact the jet's sensors or antennae positioned on the fuselage.
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uranus

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Unread post01 Jan 2012, 18:12

Seems like Conformals would be a better option in every respect except jettison capability.

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