02 Juli 2010
UAV Refueling (photo : Northrop Grumman)
Northrop Grumman dropped out of the US Air Force tanker race nearly four months ago, but a new contract award revealed 1 July shows they remain in the aerial refueling market.
In fact, Northrop plans to go one better than manned aerial refueling - the aerospace giant is now working with the US Defense Advanced Research Projects Agency (DARPA) on autonomous high-altitude refueling.
Under a $33 million deal dubbed KQ-X, Northrop will demonstrate refueling with a pair of Block 10 RQ-4 Global Hawks the company iscurrently sharing with NASA.
The ability to refuel mid-air without the aid of a pilot on the ground would extend the Global Hawk's time on station from 30hr to 35hr hours to a matter of days, Gamache said.
"By getting rid of the pilot, we're exceeded the limits set by human biology. Now we are set to remove the limits of fuel. From there, the Global Hawk's limitations will become a matter of system reliability and payloads," he said.
The program will bring together Northrop, DARPA, NASA and the National Oceanic and Atmospheric Administration to retrofit two Global Hawks for an entirely autonomous hose-and-drogue refueling system.
The receiving aircraft will be fitted with a 4.3m (14ft) probe and the "tanker" drone will get a hose and drogue system installed in its nose, where the synthetic-aperture radar usually resides.
For now, the refueling attempt will be on the centreline using GPS and an optical tracking system to make connections and transferring fuel between the fuselage tanks, said Mark Gamache, Northrop's director of advanced programs and technology.
"Once we prove the technology, then we'll maximize the amount of fuel that can be transferred in and out of wing tanks on both birds," he said.
The program will also mark the first attempt to fly Global Hawks in formation, according to Northorp.
Because the Global Hawk can fly at altitudes up to 65,000ft, refueling will take place at a much higher altitude than has previously been demonstrated with manned aircraft. Most aerial refueling takes place around the 20-30,000ft range, depending on the platform.
KQ-X will build on work already done by DARPA and Sierra Nevada Corp. at NASA's Dryden Flight Research Center outside Palmdale, Calif., where the Global Hawk is assembled, Gamache said. During the Autonomous Airborne Refueling Demonstration project, a NASA-owned F/A-18 made contact with a 707-300 tanker 18 times; the program concluded in 2007.
"We've been working with DARPA for quite awhile to get to where we're at with this contract award," he said, citing October of 2008 as the date of Northrop's original proposal to DARPA.