On Dec 11, 4:45*pm, "Mr.Smartypants"
wrote:
On Dec 10, 2:21*pm, Jack Linthicum
wrote:



On Dec 10, 3:44*pm, "Mr.Smartypants"
wrote:

On Dec 9, 9:22*pm, Mike wrote:

StrategyPage.com
December 2, 2009

The Melting Deck Plates Muddle

by James Dunnigan

Earlier this year, the U.S. Navy discovered that the heat from the
MV-22's gas turbine engines, which blow their exhaust right on to the
deck of the LHD while waiting to take off, caused high enough
temperatures to the steel under the deck plates, to possibly warp the
understructure. This was already a known potential problem with the
new F-35B vertical takeoff jet fighter.
So now the Navy has two hot new aircraft that require an innovative
solution to the melting deck problem. 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 is looking for a solution that will 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 is shaping up as 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.

Distortion or warping of steel plating due to expansion from high
temperatures is a far cry from "melting".

1700 degrees was mentioned in one article.-

That would still be "distortion" not "melting".

Here are some numbers some from an amendment
BAA 09-031 Amendment 0001

Side note:
[Iron, out of the ground, melts at around 1510 degrees C (2750°F).
Steel often melts at around 1370 degrees C (2500°F).]

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.


“Structural Evaluation of an LHD-Class Amphibious
Ship Flight Deck Subjected to Exhaust Gas Heat from a MV-22 Osprey
Aircraft,” they note that deck buckling occurs at a temperature of
160oF to 170oF. Where does the 300oF limit originate?

Response: The 300 degree F is derived from the temperature limit of
the tires on aircraft.

How concentrated is the heat flux, how large an area is involved in
the 24,000BTU/min heating? I have had difficulty getting any numbers
and the information heat flux given in the BAA did not include an area
component.

Response: A range of 3-foot to 10-foot diameter is suggested.


Max exhaust temperature anticipated?
Response: This is tightly controlled. A range of max temperatures
could be 1000– 1700 deg. F.

http://www.onr.navy.mil/~/media/File...amend0001.ashx