From Landings:
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747-firebomber
Stand by for the 747 "Supertanker," the world's largest aerial firefighter.
The folks at the Evergreen Air Center Pinal Airpark in Marana, Ariz. have also done a lot of work for the U.S. Forest Service and Bureau of Land Management. But they may have outdone themselves with their latest project: a Boeing 747 firebomber called the Supertanker.
It's a former cargo plane outfitted as an aerial firefighting aircraft. The plane carries 180,000 pounds of water in a 24,000-gallon belly tank, said an Evergreen spokesman.
The water-drop testing was done, according to an FAA Notam, from Feb. 15 through Mar. 15. The world's largest air tanker operated VFR within 10 n.m. of Pinal Airpark, making drops near the airfield at altitudes from 10,000 feet msl down to 800 feet agl.
Evergreen has not yet released the results of the testing but it has high hopes for the 747 Supertanker.
With its patented, pressurized drop system, the Supertanker can disperse retardant under high pressure, allowing it to drop from an altitude of 400-800 feet, versus 200 ft. for most of today's tankers. It can also drop its entire load in eight seconds, or in several segmented drops, Evergreen said.
The Supertanker's drop speed will be around 140 knots, which provides a 30% cushion above its stall speed. During drops, it will be configured as it would be for an approach to land, with gear and flaps down.
Tanker Experience
Evergreen Aviation has long been known for its involvement in oddball aerial experiments for the CIA and other government agencies.
One of its most well known schemes was putting a Fulton aerial retrieval system in the nose of an Intermountain Aviation B-17 in the 1960s. The plane and the "Skyhook" system were featured in the 1965 James Bond film "Thunderball."
Evergreen's experience in aerial firefighting dates back to 1960, when it formed Evergreen Helicopters, which today operates 54 helicopters, 30 of which are configured as tankers. It got into fixed-wing tanker operations when it purchased Johnson Flying Service of Missoula, Mont. in 1975.
Aeronautical engineers spent more than 20,000 hours developing the Supertanker, Evergreen said. Boeing supported preliminary engineering studies and the certification of components, and will be involved in the FAA certification process.
The choice of aircraft was based on Evergreen's vast experience with the 747. Its fleet of 10 747s have logged more than 416,000 hours in the air over the past 25 years.
The Supertanker is an attempt to update the air tanker fleet, which consists mostly of ex-military transports, some of WW II vintage. Unlike most of the current tanker fleet, the 747 will fly within its original design envelope, Evergreen said.
Evergreen contends that the Supertanker, with a cruise speed of 500+ mph, will be able to put out fires in less time and require fewer aircraft and flight hours. Its 24,000-gallon load of retardant is seven times larger than that of the most modern tanker, the Lockheed P-3 Orion.
What becomes of the Supertanker depends on the results of the drop tests. Although testing of a Douglas DC-10 air tanker in Southern California last year led nowhere, Evergreen has the experience and financial backing to make this project work.
If it is as successful as hoped, it could cut the size of the air tanker fleet significantly. Or as Tony Kern, the U.S. Forest Service's top aviation official, put it: "You'd never see a fleet of 20 of these things but you might see a fleet of 10."