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    Posted by Bill Sweetman 1:38 PM on Nov 18, 2009

    US Navy amphibious ships operating MV-22B Osprey tilt-rotors will need major structural repairs after less than half their planned service lives, according to a newly released Navy document, unless a new Deck Thermal Management System (DTMS) can be developed to protect the decks from exhaust heat. The only other alternative identified so far is a heavy structural modification to the deck. The JSF is considered likely to cause similar problems.

    The problem is caused when the MV-22 is preparing for a mission and parked on deck with rotors turning. The result is localized heating and expansion, which causes visible buckling of the deck after ten minutes. According to the Office of Naval Research document, announcing a joint ONR/Defense Advanced Research Projects Agency (DARPA) program (DARPA announcement here) to search for solutions, repeated buckling is expected to cause deck failure at 40 per cent of planned ship life.

    The JSF presents a slightly different problem. Its exhaust is hotter and faster, but in normal operations will not be directed at the deck for more than two minutes. Nevertheless, the Navy expects "a severe thermo-mechanical impact" on ship decks, no doubt an immense surprise:  who could possibly have thought that an 18000-pound-thrust nozzle, blasting straight down at the deck at a distance measured in inches, might be a problem?

    ONR has teamed with DARPA to see if anyone out there can come up with a Rumplesnitz!-type solution that will make the fire-breathing dragons go away. It's not easy. The Navy wants a passive solution (no coolant pumps, for example) that can be laid down on the existing deck, and is no more than an inch thick so as not to complicate operations. It has to include an anti-skid coating, and as well as being able to dissipate heat, it has to survive the mechanical stress of aircraft movements and the JSF's blast.

    Reading the Navy and DARPA documents, it seems that what is envisioned is a layer of heat-pipes buried in a mat bonded to the deck, designed to rapidly spread the heat from the spots under the exhaust across a wider area. The goal is to keep the underlying deck structure from reaching more than 200 deg. F after 90 minutes of a parked V-22 or 120 seconds of exposure to a JSF exhaust.

    The Navy expects to award a contract or contract for DTMS development in October 2010, conduct land-based tests in 2013 and certify the technology for full-scale development by 2014.

    Tags: ar99, jsf, v-22, amphibs

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