Raptor team conducts engine, radar tests

Released: 22 Oct 1999

Installed-engine runs were successfully carried out on aircraft 4003, the third flight-test Raptor built. Another goal, initial testing of the Raptor's radar cross section, took place the last week of September.

The engine runs, conducted at facilities operated by F-22 prime contractor Lockheed Martin Aeronautical Systems, Marietta, Ga., were part of flight preparations for the third and most recent addition to the Air Force's stable of next-generation air superiority fighter jets.

The engine tests consisted of engine depreservation starts (an engine's initial start after storage), generator checks and environmental control system flow checks for both engines. The engine runs occurred Oct. 6 -- two weeks ahead of schedule -- and lasted 45 minutes.

Verification testing of the fighter's RCS signature took place at the Helendale Measurement Facility, a state-of-the-art RCS measurement facility operated by LMAS.

The tests were performed using a full-scale replica of the F-22, built to production tolerances, and incorporating numerous production components and materials -- including all major signature contributors. According to program officials, the model is the most detailed signature model ever built.

"The F-22 radar cross section full-scale pole model tests are essential to confirm both our modeling and component level characterization of the F-22's low-observable design," said Chris Blake, F-22 System Program Office technical director here. "These tests will confirm the operational signature of the F-22's design and give us confidence in the fighter's low-observable features."

During these initial phases of testing, the model was mounted upside-down, so engineers could get a good look at the bottom of the aircraft. Later, the model will be flipped over so that the top of the aircraft can be examined. Additionally, near-field RCS measurements (radar close to the model) will be taken for correlation with data taken in the F-22's indoor RCS measurement facility at LMAS.

LMAS's indoor RCS verification facility eventually will be used for verifying the signature of production aircraft prior to delivery to the Air Force.

Raptor 4003's engine runs and the RCS tests help satisfy DOD criteria, all of which must be satisfied before the F-22 will be approved for it's next phase of acquisition. Other 1999 DOD criteria previously satisfied include demonstration of the Raptor's supercruise and 60 degree angle-of-attack flight capabilities.

Each calendar year, the Defense Department, along with the Air Force, establishes a set of specific goals that the F-22 program must meet to move to its next phase. Nine such DOD program criteria were established for 1999, including supercruise -- flight at Mach 1.5 without fuel-guzzling afterburners and flight in excess of 60 degrees angle of attack.

"Only one more DOD criterion to go -- delivery of the F-22's Block 2 software to the program's flying test bed -- and we will have completed all Defense Department criteria for 1999," said Brig. Gen. Michael Mushala, F-22 System Program Office director here. "The airplane and the team are performing extremely well, this is a great success."

The F-22 Raptor is being developed to counter lethal threats posed by advanced surface-to-air missile systems and next-generation fighters equipped with launch-and-leave missiles. It is widely regarded as the most advanced fighter in the world, combining a revolutionary leap in technology and capability with reduced support requirements and maintenance costs. It will replace the F-15C as America's front-line, air superiority fighter

Raptor 4003 is scheduled to make its first flight early next year with delivery to Edwards Air Force Base, Calif., next spring, where it will be flown in the Raptor's flight test program.