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F-22 Raptor halfway through climatic laboratory tests

08/07/02 - EGLIN AIR FORCE BASE, Fla. (AFPN) -- While Eglin temperatures soared into the sizzling mid-90s, snow fell on the Air Force's newest fighter, the F-22 Raptor, which was undergoing three months of extreme weather testing here.

Eglin Air Force Base
During the tests, technicians from the 46th Test Wing will put the F-22 through grueling weather conditions ranging from extreme cold to desert-baking heat.

The aircraft does not have to leave Eglin to experience these extremes -- the laboratory provides the weather. It is the world's largest environmental testing chamber and can produce almost any weather condition in the world.

According to Brent Poulson, the F-22 combined test force climatic laboratory program manager, since the F-22 arrived at Eglin in early June, the Raptor has been subjected to cold weather tests such as ? 40 degrees with its engines running, and then ? 65 degrees without an engine run.

"We had eight inches of snow on top of the aircraft and also performed a windblown snow test," Poulson said.

About 70 people from Edwards Air Force Base, Calif., accompanied the aircraft here to analyze how the F-22 performs in weather extremes.

"We've been planning these weather tests since at least 1987, and the tests are an extremely integral part of the program," said Brig. Gen. William J. Jabour, program executive officer for fighter and bomber programs for the assistant secretary of the Air Force. The general visited the F-22 CTF recently while attending a conference here.

"It's especially critical for the F-22 [to undergo the weather tests] because of the materials and coating that give the aircraft its stealthiness." he said.

The laboratory has one main chamber and five smaller chambers. There, test engineers can create an array of weather conditions ranging from a blasting blizzard of blowing snow or a deluge of rain to freezing rain to stifling desert heat or humid, muggy heat; salt fog or sand storms. Temperatures in the laboratory can range from minus 105 degrees to 165 degrees.

During the tests, the aircraft is configured so that all its operating systems are functioning. Engineers use tie-downs and struts so that the aircraft can operate all its systems as if it were flying.

When the aircraft runs its engines, ducting carries the exhaust out of the laboratory. An air replacement system feeds in a vast amount of air that is ingested by the engines at the same temperature as the test chamber and at the same rate that the engine uses the air, Velasco said.

"Tasks during the test runs included landing gear control, control sweeps, simulated weapons launch and engine power settings up to full afterburner," Poulson said. "During the cold weather tests, overall, the aircraft performed well.

"There were some subsystem engine, support equipment and maintenance anomalies discovered," he said. "That's why we do these tests. We want to find out now so we can fix things."

Poulson, from Edwards AFB, was impressed with the laboratory's capabilities.

"It's amazing to see an aircraft on jacks inside of a hangar running the engines with one afterburner going," he said. "It's also pretty amazing that we can go from 8 inches of snow on the aircraft to 113 degrees in four days."

Upcoming tests for the F-22 include high temperature, high humidity and an assortment of rain tests including freezing, steady and wind-blown rain. The Raptor will also undergo engine icing and cold maintenance demonstrations, which test how well the maintainers can support the aircraft in cold weather.

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