We've heard how the stealthy F-22 and F-35 are flying thermos bottles, struggling under the huge heat loads imposed by their powerful engines and systems. Well it seems the latest generation of vertical-lift aircraft is turning the flight decks of US Navy amphibious assault ships into frying pans.
Photo: US Navy
The initial culprit is the MV-22 tiltrotor, but the big concern is the STOVL F-35B, which is due on deck after 2012. With nacelles tilted and rotors turning, hot exhaust from the Osprey's engines is buckling the decks, and Navy studies warn repeated buckling will cause deck failure at 40% of planned ship life. F-35B exhaust plumes are expected to have a "severe thermo-mechanical impact" on the structure and non-skid surface of the flight deck.
That's according to a new solicitation from the Office of Naval Research, which is looking for new ideas for flight deck thermal management. The solicitation is looking for alternatives to a DARPA/ONR program that is already looking at "cooled heat pipe technologies" to overcome the thermal issues.
It's not a trivial problem. For the MV-22, where the exhausts are close to the deck when the nacelles are vertical, buckling has been observed after just 10min of sitting on the deck, rotors turning. The F-35B will be in STOVL mode for a fraction of that time, but is expected to cause even more heating of the deck.
ONR is looking for thermal management technologies that can keep the deck surface temperature below 300ºF when exposed to MV-22 exhaust plumes for 90 minutes before takeoff, and F-35B exhaust plumes for 2 minutes when landing. And cooling the deck is not enough - any solution has to be compatible with the deck's non-skid coating. It also has to be affordable and capable of being installed below deck or retrofitted above deck. Tall order.
Photo: Lockheed Martin
Based on measurements taken during recent hover-pit tests, Lockheed Martin does not believe there will be an issue with deck temperatures. One acknowledged area of concern is the combined auxiliary/emergency powerpack, or IPP, which exhausts downwards on the STOVL aircraft. (It exhausts upwards on the F-35C carrier variant to protect deck crew, but downwards on the F-35B and CTOL F-35A to save weight and gain fuel volume.)
The IPP has two modes: bleed and bleed-and-burn. In bleed mode the exhaust is relatively cool, Lockheed says. In bleed-and-burn, fuel is burned in the IPP to generate more power, and exhaust temperature rises. Because of operator concerns about surface heating, Lockheed says the pilot will have the ability to switch the IPP back to bleed mode if holding on the runway, or deck.
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jetcall1: the Navy's biggest concern with deck handling is noise, and damage to both hearing and internal organs (and not just with F-35 - the F/A-18E/F may actually be noisier on deck). There is a lot of research under way in that area
I have never seen a photo of a V-22 on deck in this mode, probably because the deck bosses will never permit that.
1. The rotors will become man-eaters and whack several sailors and Marines each year.
2. The downwash and heat will blast people and aircraft behind them, especially if pilots rev up the engines to check response.
3. This will cause a V-22 to want to move forward, so it will strain brakes, and lead to occasionally accidents as a V-22 lurches forward and whacks people.
This is why this "solution" was never used in the hundreds of shipboard flights these past ten years.
How many years and billions of dollars will it require to modify the amphib fleet with coolants? Meanwhile, there are no CH-46Es in the East Coast, so who would fill the gap for a decade. This has been known decade, and reported in detail at places like www.g2mil.com
FYI, that photo is a typical V-22 startup. So much oil leaks that it must be topped off after each flight. When it starts up, all the leaked oil burns off.
carlo - I know I took a liberty with the V-22 startup picture, but it was a fun shot.
ELP - I do the puns round here
when the V-22 rotors are in the "helicopter" position (as they will be when taking off or landing on deck) they're over 15 feet above the deck...you'd have to be one heck'va tall Marine or Sailor to get chewed by one. downwash and heat are concerns but i've never seen a pilot reving his engines full tilt when crew members might be in danger....lastly the V-22's "deck" configuration will NOT cause a V-22 to lurch forward. wow, check out its operating profile before you start blasting away without a clear sight picture. g2mil ..Carlton Meyers???. his association with another famous disgruntled Marine makes anything from his site suspect in my opinion but to each his own.