Fuel Temperature Can Shut Down F-35
(Source: Defense-Aerospace.com; published Dec 08, 2014)
By Giovanni de Briganti
The US Air Force has had to paint its fuel trucks white to keep the fuel inside from overheating as the F-35 has a fuel temperature threshold and cannot function properly if the fuel temperature is too high. (USAF photo)
PÄRIS --- Again, another truly remarkable facet of the F-35 program is discovered purely by chance, without ever having been mentioned in any of the innumerable studies and reports on the program that have been published over the past 12 years.
Thanks to a story on the curious subject of repainting fuel trucks posted over the week-end on the US Air Force website, and reproduced below, the world has discovered that “the F-35 has a fuel temperature threshold, and may not function properly if the fuel temperature is too high.”
And if that was not enough, the US Air Force feels this is a problem of sufficient concern to look for ways to “mitigate any possible aircraft shutdowns due to high fuel temperatures in the future.”
While this may not pose operational problems to Norway or possibly Canada, other future operators ranging from Turkey to Japan to Australia, and from Israel to Italy, may be surprised to find that the F-35s they plan to buy will not be able to fly when temperatures exceed values that are routine in the summer in their part of the world.
While the USAF story does not say what the “fuel temperature threshold” is, mentioning 110 degrees Fahrenheit (43°C) shows it is a very low one, especially as tarmac or concrete used on airfield aprons reflect heat and multiply the temperature of any vehicle on the ground.
This new vulnerability of the F-35 is likely to give a new meaning to the expression “summer offensive,” as future aggressors will no doubt take the precaution of waiting for summer (or even a heatwave) to attack, knowing their opponents’ F-35s will be unable to take off and oppose them.
The two solutions devised to work around this issue are particularly inspired.
The short-term solution is to repaint F-35 fuel trucks at a cost of $3,900 each (and a week’s work), while the long-term fix is particularly brilliant: build parking shades so the fuel tanks can park in the shade.
These solutions will prove particularly useful to the US Marine Corps, whose rationale for buying the F-35B STOVL variant is the ability to deploy them on beach-heads shortly after the first landing wave. Will Sea Bees now have to plan on going ashore to build parking shades for the fuel trucks before the F-35s can land and troops can get close air support?
The existence of a temperature threshold also raises many other technical questions, the main one being how the F-35’s fuel tanks can function effectively as “heat sinks” (another design innovation) if they are already so sensible to heat that the Air Force fears “possible aircraft shutdowns due to high fuel temperatures?”
Clearly, in addition to runaway costs, an inability to reach contractual performance requirements and recurring delays, the F-35 incorporates many design innovations that, as the world is gradually discover, will end up doing far more damage than the program’s original sin of concurrency between development and acquisition, which was famously but belatedly described as “acquisition malpractice” by a senior Pentagon official.
Luke AFB Changes Refueling Truck Color, Mitigates F-35 Shutdowns
(Source: US Air Force 56th Fighter Wing; issued Dec 6, 2014)
LUKE AIR FORCE BASE, Ariz. --- The 56th Logistics Readiness Squadron recently added a new fuel truck to its fleet designed to improve mission effectiveness and safety on the flightline.
However, it’s not really a new fuel truck, but an old fuel truck with its tank painted white. What LRS Airmen once referred to as "Big Green," the “new” truck with a white fuel tank has been a little difficult for some to get used to; however, the change has a better purpose then just being aesthetically pleasing.
"We painted the refuelers white to reduce the temperature of fuel being delivered to the F-35 Lightning II joint strike fighter," said Senior Airman Jacob Hartman, a 56th LRS fuels distribution operator. "The F-35 has a fuel temperature threshold and may not function properly if the fuel temperature is too high, so after collaborating with other bases and receiving waiver approval from (the Air Education Training Command), we painted the tanks white."
With the change, the 56th LRS hopes for no delay in aircraft take-offs, all while maintaining mission sorties and ensuring pilots meet training requirements.
"It ensures the F-35 is able to meet its sortie requirements," said Chief Master Sgt. Ralph Resch, the 56th LRS fuels manager. "We are taking proactive measures to mitigate any possible aircraft shutdowns due to high fuel temperatures in the future."
The squadron adopted the idea after it was first implemented at Edwards Air Force Base, California.
In the summer months at Luke AFB, temperatures can reach beyond 110 degrees. Painting the tanks white now will help prevent fuel stored in the tanks from over-heating.
"This is the short-term goal to cool the fuel for the F-35; however, the long-term fix is to have parking shades for the refuelers," Resch said.
The white paint is special because it is a solar polyurethane enamel that reflects the heat of the sun's rays. Interestingly, after dropping off the first truck to be painted, the 56th LRS learned it is not the color that reflects the heat.
"The painting process is a two-part process, and the second part is the reflective process," said Master Sgt. Joseph Maurin, the 56th LRS fuels distribution NCO in charge. "The painter said it did not have to be a white color, so we are going to send one of the four vehicles to get painted green, if possible. We will then compare temperatures between the green and white trucks."
Luke AFBs refuelers are also deployable and a white fuel truck would stick out like a sore thumb down range. The 56th LRS is hopeful that the tanks can be painted green and still keep fuel temperatures down.
The 56th LRS has been approved to paint four trucks and it takes about a week to complete, at a cost of $3,900 per truck.