Engineers and maintainers raise the nose of an RQ-4 Global
Hawk to a 20-degree angle during fuel starvation testing.
Photo: Airman 1st Class Mike Young
10/16/2007 - EDWARDS AIR FORCE BASE, CA. -- The 452nd Flight
Test Squadron pushed the RQ-4 Global Hawk Block 20 to its fuel
system limits during a weeklong starvation test here from Oct.
1 to 4.
The testing involved tilting the aircraft to a 20-degree attitude
while running the aircraft out of fuel inside the weight and
"The testing is very important," said Lt. Col. Andy
Thurling, 452nd Flight Test Squadron commander. "It allows
us to know the aircraft's fuel requirements in case of a missed
landing. This will allow for longer flights and more efficiency
in the air."
The Block 20 carries 1,000 pounds more payload and 6,000 pounds
more fuel than the Block 10, said Capt. Stephen Leggiero, 773rd
Test Squadron project engineer. Because of the increase in weight,
additional fuel is required for the aircraft. This means an
entirely new fuel cell configuration and fuel management system
Aside from the starvation testing, the team performed a weight
and balance test on the aircraft to determine how changes in
fuel weight change the aircrafts center of gravity.
During the test, the Global Hawk was weighed then placed on
blocks to allow additional ground clearance for the tail of
After preparation, the team fired up the engines and began
to tilt the aircraft.
"We tilted the aircraft at the high 20-degree angle to
simulate a go-around situation," said 2nd Lt. Garrison
Lindholm, 773rd Test Squadron subsystem engineer.
A go-around is where the aircraft misses an approach and is
required to climb at a
steeper attitude, he said.
"We wanted to ensure that at the steep deck angle, the
pumps would not create an engine flame out resulting in engine
failure," Lieutenant Lindholm said.
The main parameter for testing was weight, he said. The testers
initially weighed the aircraft to determine its gross weight.
The team then weighed the aircraft again as it began to show
signs of starvation, Captain Leggiero said. This was to measure
the amount of fuel in the tank when fuel starvation began.
During the testing, the team used a synthetic fuel called Isopar-M
instead of standard JP-8 fuel for safety purposes. The JP-8
has a lower flash point, which is the point where fuel ignites.
"Overall, the testing went very smoothly," Captain
Leggiero said. "It really highlights some of the fantastic
infrastructure we have on base, and the wonderful people who
pulled together to make things happen."
Source: USAF Edwards AFB Press Release by Airman 1st Class