Science: Flames in the Sky

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People who live near Muroc, Calif. are used to seeing strange sights in the sky as test pilots from Edwards Air Force Base put new planes through their paces. For the past month they have seen a fearsome thing: roaring yellow flames streaking across the night, sometimes rocketing upward to mingle with the stars.

The flames over Muroc come from "afterburners" on Lockheed F94 all-weather fighters that are being service-tested to determine their capabilities under simulated combat conditions. Soon such flames will be common wherever jet planes need to use their full power. Developed only a few years ago, the afterburner has proved itself a dependable source of extra power for climbing or combat.

In principle, the afterburner is as simple as ABC. The tailpipe of an ordinary turbojet engine is lengthened and inside its throat is placed a grid of hollow, perforated cross-pieces. When maximum power is needed, fuel is squirted into the stream of hot gas racing out of the tailpipe. There is plenty of heat to ignite it and plenty of oxygen to keep it alight. So a vast yellow flame bursts out of the pipe, and the plane gets a mighty shove forward.

The actual performance figures of up-to-date afterburners are secret. The great flames are probably inefficient, using floods of fuel. But they will toss a fighter up to 40,000 feet in half the time that would be needed without them. For an interceptor like the F-94, a few minutes saved in climbing might mean success in downing an enemy bomber.