"JSF PROGRAM TO EXAMINE STOVL DOWNWASH IN UPCOMING TESTS"

Inside the Navy - 4/20/2009
'It's a significant issue'
HEINZ: JSF PROGRAM TO EXAMINE STOVL DOWNWASH IN UPCOMING TESTS

Program officials will start taking a closer look in tests soon at how
the hot, powerful downwash from the Marine Corps' short-take-off,
vertical-landing (STOVL) variant of the F-35 Joint Strike Fighter
would affect the decks of amphibious assault ships, according to
Marine Brig. Gen. David Heinz, JSF program executive officer.

The first STOVL test aircraft, BF-1, is currently undergoing tests on
top of a hover pit -- a hole in the ground fitted with sensors and
covered with a grate to collect data -- in advance of tests beginning
in May in Fort Worth, TX, in which the aircraft would use the STOVL
lift fan in flight for the first time. Full STOVL flight is scheduled
for July at Naval Air Station Patuxent River, MD.

The program plans to use the upcoming tests to examine the aircraft's
downwash, Heinz told Inside the Navy in an April 7 interview at the
JSF program office in Arlington, VA.

"At the end of the hover pit cycle, we're going to plate over a
portion of it to start getting some of the downwash data on the hover
pit," the brigadier general said. "We'll also collect thermal data at
the same time to see if there should be any concern relative to what
temperature environment I might induce on the decks, on ships, on
asphalt, et cetera, to see if there's a thermal issue relative to
steel plate heating on the amphibs."

Navy officials have expressed concern that the powerful, high-
temperature downwash caused by the STOVL's lift fan could damage
ships' antennas and radars stationed in the rear, as the aircraft is
more powerful than legacy AV-8B Harriers. Heinz, however, told ITN
last July that officials should not jump to the conclusion that it
will be a problem and instead wait until tests are conducted on the
aircraft.

Integration of the JSF on the existing fleet of big-deck amphibious
assault (LHD) ships is expected around the 2013 time frame, according
to Capt. Jeff Riedel, the Navy's program manager for the vessels (see
related story).

Heinz said on April 7 he thinks he is "collecting all the right data"
to make an informed decision on the issue, and more testing will be
done once the aircraft is moved from Fort Worth to Pax River, where it
will conduct tests in full STOVL mode.

"Once we come off the hover pit, we're going to do the same thing
again here at Pax River . . . to quantify how much downwash we are
actually seeing and then also what are the temperature effects on the
materials."

The program is using a portion of a ship mock-up that includes the
metal plate, stringers, rubber sealants, or other components that
might be found on the deck, he said.

"It's a significant issue," he said. "I need to collect more data so
we can have an intelligent discussion on potential impact."