Science: Loft Bombing

Problem: how to drop an atom bomb from treetop level—and live to file a report. The solution of this esoteric flying problem is a scientific version of the “toss-bombing” that was used in the Korean war, when pilots of fighter-bombers released their bombs with an upward flip of the plane so that the bomb was tossed into caves sheltering enemy troops. Both Air Force and Navy have been working to upgrade toss bombing into a way of dishing out atom bombs safely. Last week a little information about the new technique was made public.

On the Deck. Bombers that stay at high altitudes are in no danger from the atom bombs that they drop, but their marksmanship is not accurate enough. Another disadvantage: high-flying bombers show up conspicuously on the enemy’s radar screens, and can be attacked by missiles and interceptors. Flying “on the deck” is better in many ways. Radars usually cannot see a low-flying fighter-bomber, and most missiles cannot attack it effectively. Its bombing can be made extremely accurate, but if it uses any ordinary bombing system, such as dive-bombing, it is apt to be vaporized by the fireball springing up under its tail.

The best way to avoid this misadventure is “loft-bombing,” which uses the speed of the airplane to make the bomb behave like an artillery shell. The airplane is equipped with a “black box” of gyros and electronics named LABS (Low Altitude Bombing System), manufactured by Minneapolis-Honeywell Regulator Co. The plane approaches the target flying as low as possible to keep below the enemy’s radar. The atom bomb under its belly has been set to explode in the desired manner, at a predetermined altitude, or after actually penetrating the ground. The LABS apparatus has been cranked full of information, and the pilot has been briefed to head for a landmark just short of the target. As he approaches it, he levels and steadies the plane’s flight and flicks a switch. LABS takes charge of the airplane; it pulls the plane up in a climb so steep that the pilot almost blacks out. When the angle is just right, LABS releases the atom bomb, which separates from the airplane and soars in a rising trajectory (see diagram). As soon as he is able, the pilot resumes control.

How far or high the bomb can be tossed depends on many factors, some of which are secret. When flying very low, the airplane cannot use its top speed because the bumpiness of low-level air would keep it from making a steady bombing run. But it flies pretty fast nevertheless, and if it is flying at 500 m.p.h. (733 ft. per second) when the bomb is released, the bomb starts its curve with the muzzle velocity of an 81-mm. mortar shell, whose range is two miles.

Over the Shoulder. The main advantage of loft-bombing, however, is not the range of the bomb, but the time that it spends in the air while the airplane is making its getaway. This figure is secret too, but if air resistance is ignored, a bomb tossed upward at 750 ft. per second will rise for about 23 seconds and fall for about the same time. This will give the airplane 46 seconds to turn itself upright and streak for safety before the bomb explodes.

An even more spectacular type of loft-bombing is used when there is no good landmark to sight on near the target. In such cases, the pilot sets his LABS apparatus for “over the shoulder” bombing, and pulls up into his climb when he is directly over the target. LABS does not release the bomb until the climbing curve has progressed a little beyond the vertical. When the bomb leaves the airplane, it rises in an almost vertical trajectory. It is not quite vertical, however. To compensate for the horizontal distance that the airplane covered after it passed over the target, the bomb falls slightly backward, toward the direction from which the airplane came. When it explodes, the airplane is well out of danger.