Evergreen International Aviation was poised to begin water-drop flight tests of its converted Boeing 747-based Supertanker firefighting aircraft late last week. High-altitude "dry" flights of the converted 747-200F freighter, fitted with a proof-of-concept tank system, were conducted in February.
Low-altitude "wet" tests were planned to begin at Marana, Arizona late last week. The Supertanker can carry 91,000 litres (24,000USgal) of retardant in main-deck tanks, delivered through four nozzles in the lower fuselage aft of the wing.
Work on the Supertanker began after the devastating 2002 fire season, and late last year Evergreen responded to a request for information on a next-generation aerial tanker from the US Department of Interior. "We are waiting to hear back," the company says.
Studies suggest it will take around 7min to fill the tanks. Retardant will be pressure-delivered over an 8-10s period - with the Supertanker flying at 130-140kt (240-260km/h), 500-800ft above ground level - to ensure the aircraft remains within its load-factor limits. Evergreen plans to operate a fleet of Supertankers converted from freighters within its 747 fleet.
Evergreen's Oregon-based airline division has a fleet of 10 747-100/200 freighters used for international and domestic cargo services.
GRAHAM WARWICK / WASHINGTON DC
Source: Flight International
