Sky High in a Starfighter

My climb to the top in the F-104.

Zoom climbs in the rocket-boosted NF-104 could top out at 120,000 feet in zero gravity. (Courtesy George J. Marrett)
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How the F-104 Starfighter Was Born

During the Korean War, the U.S. Air Force became concerned about the advantage the Soviet MiG-15 had over the Lockheed F-80 Shooting Star and the North American F-86 Sabrejet. The MiGs were lighter and had a greater thrust-to-weight ratio, so they could climb faster and reach higher altitudes than the U.S. fighters. The Air Force was downing 12 aircraft for every one it lost, but that was believed to be due to superior pilot proficiency. The Air Force wanted a jet fighter that would exceed the MiG’s performance in every category.

Chief designers Kelly Johnson of  Lockheed and Lee Atwood of North American Aviation were invited to visit South Korea to talk with Air Force combat pilots. The two men learned that the pilots wanted greater speed, power, and maneuverability.

New aircraft  were already in design or under construction: North American’s F-100 Super Sabre and McDonnell’s F-101 Voodoo, both of which used the Pratt & Whitney J-57 engine. Johnson decided he had to use a more advanced engine. He considered several but chose the General Electric J-79. It was unproven and using it carried some risk, but it had higher thrust than the J-57; if the pilots wanted speed, Johnson would give it to them.

The revolutionary new jet would have Mach 2 speed, be unequaled in time to climb, operate at over 60,000 feet, and combine the attributes pilots wanted. Johnson had to keep airframe weight and drag low. A very thin, straight wing offered excellent performance at high speed. A delta wing has less drag per square foot at transonic speed, but its lift during takeoff and landing is reduced. To compensate, designers had to double its area, so the total drag of a delta wing was greater. The high speed regime, combined with a high thrust-to-weight ratio, pointed to a low-aspect-ratio (in a word, stubby) wing, because it would produce less drag. Johnson proposed a wing so thin and sharp—the leading edge had a radius of only 0.0016 inch—that the edges had to have covers to prevent nicks and keep people from cutting themselves. Ice would not build up on the edge, so there was no need for heavy de-icing equipment. The wings were located  nearly two-thirds of the way back on the fuselage, and the tips were squared off, permitting the installation of jettisonable fuel tanks or the Starfighter's primary armament, a pair of AIM-9 Sidewinder heat-seeking air-to-air missiles.

The vertical tail extended about as high as the wing extended sideways, so the vertical tail would contribute a large dihedral effect; dihedral tended to restore the fighter to straight-and-level flight. To moderate the overall dihedral, the wings had 10 degrees of negative dihedral. They drooped a little.

The Starfighter had a “flying tail”—the entire horizontal surface moved—placed high above the engine exhaust, so it could be made of aluminum instead of heat-resistant but heavier stainless steel. Even at Mach 1.5 the flying tail was very effective, allowing the pilot to pull five Gs in a turn at 35,000 feet.

Johnson’s fighter never got a chance to tangle with any MiGs, but if it had, it would have left them in its contrails.

The Home Front

When I was selected for test pilot school at Edwards Air Force Base, my wife Jan was delighted. But she was concerned about the number of pilots killed during my previous assignment and wondered if test flying would be even more dangerous.

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