CTF evaluates Block 20 Global Hawk system

  • Published
  • By Airman 1st Class Julius Delos Reyes
  • 95th Air Base Wing Public Affairs
EDWARDS AIR FORCE BASE, Calif. --  The Global Vigilance Combined Test Force conducted a milestone engine run and completed the first of several taxi events for the Global Hawk Block 20 at Air Force Plant 42 in Palmdale, Calif., Sept. 26 and 27.

The team conducted a safety-of-flight engine run to evaluate the Global Hawk and its interaction with the ground control elements of the aircraft system.

"The primary importance of this testing is to provide confidence to the entire test team and the program's leadership that the Block 20 of the Global Hawk system is ready to taxi and complete a first flight," said Thomas Bryson, Global Hawk Flight Test Northrop Grumman manager for test support activity.

During the safety-of-flight engine run, maintenance, aircrew and engineering personnel monitored all aircraft systems and recorded detailed telemetry data for analysis, Mr. Bryson said. The outcome of this analysis is part of the recommendation package that clears the aircraft and ground control elements for initial taxi testing and then first flight.

This testing marks the beginning of a combined developmental and operational test phase for the evolving Global Hawk system, said Kirk Harwood, Air Vehicle lead engineer. Initial operations testing includes taxi tests, takeoff abort tests, a first flight, envelope expansion and associated sensor and ground segment tests.

The safety of flight-engine-run began with a team of maintainers and a Global Hawk pilot at Palmdale starting the engine, Mr. Harwood said. The onboard telemetry system transmitted test data to Edwards range telemetry-van that transmits data to an Edwards' South Base mission control room, where it is decoded and translated into understandable displays.

CTF engineers in the control room began monitoring the operation of the engine, controls and other systems. The air vehicle went through its built-in test and the maintainers, or the pilot, executed various commands so those in the MCR can see the systems respond to these commands.

"The safety-of-flight engine run is somewhat of a 'graduation exercise,'" Mr. Harwood said. "The design and system engineers have endeavored for years to refine their ideas with wind tunnel, hardware in the loop, and other simulations. The SOF engine-run is their final opportunity to see how the air vehicle operates before the risks to the aircraft increase significantly. Tests subsequent to this will become the responsibility of the 412th Test Wing."

The Global Hawk block 20 version is a definite improvement over the block 10 configuration, Mr. Bryson said. The block 20 aircraft is a larger aircraft with the wingspan increased from 116.2 feet to 130.9 feet. The fuselage is now 47.6 feet in length, an increase from block 10 variant's 44.4 feet. The payload capacity also increased from 2,000 pounds to 3,000 pounds.

External differences include new main landing gears that are more outboard on the wings, Mr. Bryson said. The main landing gear system now has a single wheel on each strut. The braking system is now electric with redundant electromechanical actuators. A differential braking function is added for improved ground steering during aborted takeoff or landing rollout. Several radomes on the aircraft have been modified and enlarged.

According to Mr. Bryson, the Allison Rolls-Royce engine used on the Block 10 aircraft still powers the new Block 20 jet, but a new 25 kVA generator attached to the engine accessory gearbox provides additional electrical power to all aircraft systems and payloads. A new single point pressurized fuel and de-fuel system is added, as is a new fuel quantity measurement capability. This feature provides the Global Hawk pilot with increased situational awareness of total fuel available.

Shortly after the safety of flight-engine-run, the team rolled into taxi testing, Mr. Harwood said. These tests will build up primarily in ground speed, mainly to evaluate the new electric braking system, but also to see how other developmental systems operate or ensure systems carrying over from the Block 10 air vehicle integrate properly into the Block 20 air vehicle. This testing is expected to take about two weeks before the team feels comfortable enough with how the system is working to take the next step.

Next, the team will begin a set of takeoff abort tests, he said. These tests take the air vehicle to higher speeds and check the navigation and flight control systems operate accurately and change to the correct modes for flight. This is the first time the mission plan will introduce the possibility of taking the air vehicle airborne. After a day or two of testing, the team expects to have the information necessary to judge if the air vehicle is ready for flight.

The last of the first tests is the first flight. The first flight delivers the air vehicle to Edwards from Palmdale Plant 42 and provides the team an opportunity to check and make sure the entire air vehicle is working as expected while airborne. This will be a one day test event.

After these firsts, the team will begin a series of tests to expand the flight envelope, test new sensors, and test new ground station components, Mr. Harwood said. This testing is planned to last about two years, though follow-on testing is also planned.

The Global Vigilance Combined Test Force is composed of maintainers, engineers, pilots and project managers from 452nd Flight test Squadron, 412th TW, Air Force Flight Test Center Organizations, Northrop Grumman Corporation, and Air Force Operational Test and Evaluation Command.

"This team represents a more tightly integrated government-contractor team than ever before on the Global Hawk test program," Mr. Harwood said. "It also represents a more influential role for flight test engineers, who have been tasked with technical reporting responsibilities by the 303rd Aeronautical Systems Group for the first time.