Tests Prove That Tailless, Unmanned Jet Can Operate Safely in
All Planned Flight Test Environments
The U.S. Navy's second X-47B Unmanned Combat Air System (UCAS)
will be able to withstand all of the structural stresses and
strains associated with takeoff, flight and landing - including
those uniquely linked with landing or taking off from the moving,
pitching deck of an aircraft carrier. That's the conclusion of an
analysis by a Navy/Northrop Grumman Corporation test team following
a rigorous, five-week series of structural proof tests of the jet's
airframe.
The tests on X-47B air vehicle 2 (AV-2), conducted at Northrop
Grumman's X-47B assembly and test facility in Palmdale, were
completed Jan. 24, one week ahead of schedule. Northrop Grumman is
the Navy's prime contractor for the Unmanned Combat Air System -
Demonstration (UCAS-D) program.
"The proof tests validate the structural design of the aircraft,
and give us confidence that we can operate this plane safely and
reliably in all anticipated carrier environments," said Janis
Pamiljans, vice president of the Navy UCAS program for Northrop
Grumman's Aerospace Systems sector. "In particular, we now know
that AV-2 can handle the stresses, strains and dynamic loads
associated with catapult launches and arrested landings on the
carrier deck, and air-to-air refueling."
AV-2 is identical to the first X-47B UCAS demonstration aircraft
(AV-1) - which successfully completed its historic 29-minute first
flight at Edwards Air Force Base, Calif. on Feb. 4 - except that it
will be equipped with aerial refueling equipment. Northrop Grumman
plans to use AV-2 to demonstrate unmanned air-to-air refueling -
using both the U.S. Air Force's boom/receptacle approach and the
Navy's probe and drogue approach - in 2014 as part of a technology
demonstration related to the current UCAS-D contract.
The proof testing performed on AV-2 simulated eight design
conditions, such as a 3-G symmetrical pull up and a 2.4G rolling
pullout; and five conditions expected to occur on the ground,
including takeoff and landing, said Sarah Beaudin, Northrop
Grumman's AV-2 manager.
One of the ground tests included pulling on the nose gear (to
simulate a catapult launch) and the tail hook (to simulate an
arrested landing on the carrier deck) at the same time to provide a
special combined load case for test with the required margins. One
of the flight conditions simulated the forces produced by
turbulence that could occur during air-to-air refueling, a more
demanding requirement than that used to proof test AV-1 in
2009.
"To perform the testing, we bonded pads to 200 points on the
airframe surface, and then pushed and pulled on those pads using
hydraulic jacks to simulate various static and dynamic load
conditions," explained Beaudin. "By measuring the stresses and
strains experienced by the airframe in this test environment, we'll
also be able to measure and interpret more accurately the stresses
and strains experienced during flight."
Proof testing is one of the last few tests that AV-2 will
undergo in Palmdale before its transition later this spring to
Edwards Air Force Base for more system tests, taxi tests and first
flight. Before that move occurs, the test team plans to test and
calibrate the aircraft's fuel system, and paint the aircraft.
Under a UCAS-D contract awarded in 2007, Northrop Grumman has
designed, developed and produced two X-47B aircraft. In 2013, these
aircraft will be used to demonstrate the first carrier-based
launches and recoveries by an autonomous, strike-fighter sized
unmanned aircraft. The UCAS-D program will also be used to mature
relevant carrier landing and integration technologies, and to
demonstrate autonomous aerial refueling by the X-47B aircraft.
Northrop Grumman's UCAS-D industry team includes GKN Aerospace,
Lockheed Martin, Pratt & Whitney, Eaton, GE, Hamilton
Sundstrand, Dell, Honeywell, Goodrich, Moog, Wind River, Parker
Aerospace and Rockwell Collins.