Naval Air: Yet Still Another Embarrassing F-35 Problem


December 3, 2010: The U.S. Navy has yet another problem with the new F-35 fighter it will soon be operating off its carriers. It seems that no one bothered to check if the engine for the F-35C could fit into the C-2 aircraft the navy currently uses to deliver jet fighter engines to carriers. Normally, carriers go to sea with 30-35 spare engines for their F-18 fighters (that the F-35s will replace). In the course of a six month deployment, a dozen or more of these engines will be flown to, or from, the carrier.

The F-35 engine can be disassembled into five major components, and the largest of these can be carried by sling under an MH-53E helicopter or V-22 tilt-rotor aircraft. Both of these aircraft are normally carried by amphibious ships, along with a battalion of marines, and are usually near a carrier task force. But the range for the MH-53E (carrying the heaviest component) is only 550 kilometers, if the weather is good. The V-22 has had problems landing heavy sling loads on carriers, and more research is needed there. The heaviest component, including the shipping container, weighs 4.3 tons, and is too heavy to transfer at sea using the normal methods of underway replenishment (with the supply ship moving along side and using cables and hoses to move material and fuel.) This leaves delivering the engine via the supply ship. This requires very calm weather, and getting close enough to use cranes to haul the engine aboard the carrier. This can be tricky, even in good weather, on the high seas. All this is a big problem, as within eight years, F-35Cs will be operating off Nimitz class carriers, and getting fresh engines on, and broken ones off, will become a real issue. The navy will improvise some kind of solution, but this is not the first major hassle with F-35s operating on carriers.

Nearly three two years ago, the U.S. Navy discovered that the engine exhaust heat from its two newest aircraft, the tilt-rotor MV-22 and the vertical takeoff F-35Bs, was too hot for the deck plates on some of the carriers. The gas turbine engines of both aircraft, which blow their exhaust right on to the deck of the carrier while waiting to take off, caused high enough temperatures to the steel under the deck plates, to possibly warp the understructure. The navy also discovered that the exhaust heat problem varied in intensity between different classes of helicopter carriers (each with a different deck design.)

The navy sought a solution that would not require extensive modification of current carrier decks. This includes a lot of decks, both the eleven large carriers, and the ten smaller LHAs and LHDs. This began looking like another multi-billion dollar "oops" moment, as the melting deck problem was never brought up during the long development of either aircraft. Previously, the Harrier was the only aircraft to put serious amounts of heat on the carrier deck, but not enough to do damage. But when you compare the Harrier engine with those on the V-22 and F-35B, you can easily see that there is a lot more heat coming out of the two more recent aircraft. Someone should have done the math before it became a real problem.

In any event, inexpensive solutions were found, sort of. For the MV-22, the navy developed portable heat shield mats, that deck crew could drag into place under the exhausts of the MV-22s, if these aircraft were expected to be sitting in one place for a while.

For the F-35B, the heat shield mats don't work as well (the F-35B engines put out more heat), so the exhaust nozzle on the F-35B engine is being redesigned, to spread the exhaust over a larger area, thus lowering the peak heat build up to the deck plates. This would also help solve the problem of the F-35B turning asphalt surfaces to a liquid state. Both the MV-22 and F-35B are expected to continue creating "heat management" problems. In contrast, the weight problems with the F-35 engine are not nearly as worrisome.





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