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Aeronautical Engineering
Lockheed Martin Skunk Works is in the UAV race with Polecat demonstrator
Aviation Week & Space Technology
07/24/2006, page 64
Amy Butler
Washington and London
Lockheed Martin Skunk Works enters the UAV race with Polecat
demonstrator
Printed headline: NOT TO BE LEFT BEHIND
Lockheed Martin's newly unveiled Polecat unmanned aerial system demonstrator is designed to explore
the aerodynamic characteristics of the tailless flying wing design at higher altitudes than attempted
to date, and possibly feed technologies into future aircraft for the U.S. Air Force.
The company's Advanced Development Programs sector, commonly called the Skunk Works, had been rumored to be
working on a secret unmanned aerial system (UAS) project for years. And, company officials are lifting the
veil in an attempt to quell critics who have said Lockheed Martin has been too focused on its manned
fighter business--with multibillion-dollar F-22 and F-35 programs--thereby neglecting future opportunities
with unmanned systems.
<img src="http://img230.imageshack.us/img230/7572/polecat03vk0.jpg" border=0>
With the Polecat prototype, the company is aiming at Boeing's and Northrop Grumman's turf--developing combat
UAS for the U.S. military and, possibly, the U.S. Navy's yet-to-bedefined Broad Area Maritime Surveillance program.
The Polecat UAS flies at low altitude last July at Nellis Test Range in Nevada. Credit: LOCKHEED MARTIN PHOTOS
<img src="http://img232.imageshack.us/img232/5046/polecat02qx3.jpg" border=0>
Skunk Works, noted for rapid prototyping and such technological feats as the high-flying U-2 and
speedy SR-71 reconnaissance aircraft, selected a tailless "Horton" wing design first used by Germany
in World War II. Without vertical structures and a tail, the 90-ft. wingspan vehicle is inherently
low-observable but it has not been "coated" with radar-reflecting materials because it is not expected
to fly operationally.
A new "twisting strut" inside the Polecat's wings is designed to flex in air and improve the laminar
flow over its swept wings, propelling the UAV to high altitudes. Aircraft such as the straight-winged
U-2 have traditionally behaved like gliders but lack a survivable design. "No one has ever developed in
this configuration a high lift-to-drag ratio, and we are going to do it higher than anyone has done it,"
says Skunk Works Executive Vice President Frank Cappuccio. The engine
inlets (see the cover photo) are designed to deflect radar energy away from the engines, masking some
signature, although Frank Mauro, Lockheed Martin's director of unmanned
systems, admits more work is needed to improve low observability.
Intended to soar to a 60,000-ft. altitude and higher, Lockheed Martin has two main mission areas
in mind for Polecat: the Air Force's yet-to-be defined Long Range
Strike (LRS) system and a next-generation
intelligence, surveillance and reconnaissance aircraft. So far, the flying wing has not flown that high. Mauro says
the B-2's 45,000-50,000-ft. operating area is the Horton's ceiling to date. "The air gets pretty
thin above those levels. Our main objective is to determine how
effective that wing concept
is at that altitude so we'll have better data if we should [develop] something that requires that design."
Cappuccio says that in the
coming months engineers are devising sensors for Polecat that are part of a contrail suppression
system. Contrails often give U-2s away despite altitude. So,
Skunk Works wants to detect conditions conducive to contrails and avoid these areas.
During its first two flights at the Nellis Test Range, Nev., last year, Polecat reached 15,000 ft.,
a limit set by the portion of the range where it was flying. Officials are now moving operations
to another area of the proving ground. Cappuccio, who unveiled
Polecat to the media during a briefing
at the Farnborough air show last week, says high-altitude flights are expected as soon as September.
Powered by two FJ44-3E Williams International engines, Polecat has a 9,000-lb. gross takeoff weight.
A bay nestled between the two engines can accommodate 1,000 lb. of sensors or weapons. Skunk Works is
negotiating with various sensor makers for potential demonstrations,
possibly conformal radar arrays.
Cappuccio adds that he wants to experiment with conformal antennae on the vehicle.
Engineers designed Polecat using 98% composites, aside from landing gear, avionics and engines, and it
consists of fewer than 200 parts--all to bring costs down. They used an innovative, low-temperature composite
curing process for the vehicle. Normally cured at 350F in an autoclave, the new technique relies
on a 150F curing process that eliminates the need for investing in autoclaves. The composites are then
post-cured. These are further iterations of processes used in the F-22, F-35 and Joint Air-to-Surface Standoff Missile programs.
Mauro says that UAS costs can be further cut by reducing manpower required for operation. Unmanned
aircraft have been vulnerable in the Pentagon's cutthroat budget environment because they remain as
pricey as their manned counterparts.
Flight tests in 2007 will explore a triple-redundant flight control system and software to "leapfrog"
existing UAS autonomy capabilities. Polecat is designed to take off and land autonomously. The government
is already pursuing a system whereby four UAS vehicles can be
monitored by one person. However, rules of engagement require many more looks at targets prior to
engagement by a UAS. Although Mauro acknowledges the military's
doctrine will have to catch up, the company is working on an autonomous target ID capability.
In response to criticism that Skunk Works has not been pursuing UAS technology, Mauro says, "We've taken
some hard shots in the past three or four years that [we were]
not in the UAS game, and there is a perception that our future is at risk. We are putting our money
where our mouth is." The demonstrator was ready for first flight in 2004, 18 months after the go-ahead
to begin work and at a cost of $27 million to the company. Another
$5 million has been spent to continue work since then, Mauro notes, adding that the funds are a "significant" portion
of Lockheed's aeronautics research investment.
While Boeing and Northrop Grumman have each reaped technical and financial benefits of the respective
X-45 and X-47 Joint Unmanned Combat Air System demo programs, Lockheed Martin lacked government support.
Mauro admits Skunk Works is playing catch-up in some respects, and that Polecat is not meant to be a product
in itself but rather to demonstrate technologies such as autonomous flight and the use of new
composite techniques and adhesives. "Transformation was the key-word
for the period and UASs were a mechanism for transformation. We were, effectively, on the outside
looking in relative to our participation on J-UCAS."
But freedom from government involvement has also worked in Polecat's favor. By contrast, J-UCAS,
with operational assessments planned to begin in Fiscal 2008, has suffered from fitful funding
and shifting requirements. USAF pulled out last year in favor of ongoing
studies on future strike concepts.
Most immediately, Polecat could also contribute to a design that would encroach on the duel between
Northrop Grumman's Global Hawk and a souped-up General Atomics Aeronautical Systems Predator,
called Mariner, for the U.S. Navy's Broad Area Maritime Surveillance program. It could raise questions
about the future of Lockheed Martin's partnership with General Atomics on Mariner. If the Navy
decides it wants a low-observable aircraft, Lockheed Martin would be relieved of its partnering obligation
to General Atomics, Cappuccio says.
Brownells calls me Aaron Burr cause the
way I'm droppin Hamilton$
Edited by - boomer on Jul 28 2006 13:06
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