Anatomy of Speed

Few airplanes now flying have provoked such far-out speculation as Lockheed's long-secret All. Since President Johnson gave the plane a sort of partial unveiling, it has been called "quasi-ballistic" and "suborbital"; it has been classed just below a Mercury capsule. Dopesters have fitted it with a rocket engine to boost it out of the atmosphere like the X-15 research plane.

Many of the far-out theories seem far from fact, but the All is nevertheless an extraordinary airplane, a technical generation ahead of any of its competitors. Lockheed's famed designer Clarence L. ("Kelly") Johnson started building the ship in 1959 as a successor to the U-2 high-altitude reconnaissance plane. Though it was the altitude champ of its day, the U-2 flew so slowly (500 m.p.h. at 70,000 ft.) that the Russians were eventually able to shoot one down. The All was specifically designed to fly high enough and fast enough to avoid trouble.

According to the authoritative magazine Aviation Week, the All was trucked in pieces out of Lockheed's secret "Skonk Works" at Burbank, Calif., and assembled for flight testing at a hidden Nevada base called "The Ranch." When its secret could no longer be kept, the airplane was described misleadingly as an "interceptor." It is more likely to be anything but. It sacrifices everything for extreme speed at extreme altitude (probably above 125,000 ft.), where there is nothing to intercept.

Speed & Thrust. Most authorities credit the All's performance to its lightness, its radical double-delta wing and its equally radical engines. The weight depends largely on lavish use of titanium, which is not much heavier than aluminum, but stands the searing heat of Mach3 flight. Titanium alloys sell for more than $5 per Ib. and are difficult to fabricate, but advanced airplanes are no respecters of cost.

The All's double-delta wing is a shrewd solution to the difficult problem of sustaining flight at three times the speed of sound while still providing good control for reasonably slow-speed loitering and landing. The broad, rear delta develops high lift at moderate speeds, but as a swept-wing plane moves faster, its center of lift shifts rearward towards the tail. If it is not counteracted in some way, this shift will make the plane dangerously nose heavy. A pilot might use his elevators to hold the nose up, but this maneuver would cause costly drag. The All licks the problem in a simple and straightforward manner; it has small lifting structures ahead of the main delta. They give almost no lift at low speed, but as speed picks up, their lift increases greatly and supports the nose. Much of the high-speed lift comes from narrow fairings that run along both sides of the long, slim fuselage and also serve to stiffen it. Aviation Week says that the space between the engine nacelles is mostly filled with a thick, winglike structure to store fuel.

The All's two Pratt-and-Whitney engines are as remarkable as its wings. The two turbojets have intakes six feet in diameter that gulp enormous amounts of the thin air at high altitudes. Lightened by liberal use of titanium, the engines have hollow turbine blades made of porous material. Air or some other gas forced through the pores keeps the blades from softening, despite the fact that fuel is burned at far higher temperatures than can be tolerated by most engines. The higher temperature yields several thousand more pounds of thrust without added cost in fuel.

Total thrust is about 34,000 Ibs.

The power plant uses a special kerosene-based fuel that contains additives to keep it burning at extreme altitudes. There is some means of narrowing the air intake when operating near the ground so that the engines will not be choked by dense, low-altitude air.

High & Thin. The All's combination of low weight and high power permits it to take advantage of the fact that air at high altitude is so thin it offers little resistance. As the plane climbs higher, it flies faster, and its engines swallow more air through their gaping intakes. But the All finally must reach an altitude where the air is so thin that its engines cannot gather enough oxygen to keep them roaring healthily. Above this point the plane slows down despite the diminishing resistance. Most experts are convinced that the All's top speed is considerably above the 2,000 m.p.h. with which it is officially credited, and that it makes its best speed somewhere around 70,000 ft. Below this level the ship is slowed by drag; above it, the engines begin to suffer from air starvation.

Bomb & Camera. If the All is flown over hostile territory, it may well be spotted by radar, but no known aircraft can touch it. Even the present versions carry electronic sensors under their wings and a heavy load of long-range cameras. In the event of nuclear war, a plane with the All's capabilities could fly high over a hostile land after a missile strike; its crew could note whether selected targets have been hit and destroyed. If any are still surviving, the All could radio for another salvo of Minutemen, which would arrive in 30 minutes. It might even drop an H-bomb itself, but this would not be easy. When an All type speedster gets near enough to a target to observe it clearly, it will have already passed the optimum release point. Its bomb will have to curve back to the target under some kind of guidance.

Happily, the peaceful value of the All outweighs its military possibilities. Except for the X-15, which uses impractical rocket propulsion for short bursts of speed, it is the fastest airplane that has ever flown, and it has accumulated vast experience in Mach 3 flight. It is not an airliner itself; it carries only a three-man crew, and most of its fuselage is crammed with fuel. But the great supersonic airliners that the U.S. is anxious to start building will fly at All speed and altitude. In many vital aspects they will be the children of Kelly Johnson's latest creation.

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