Self-Knockout

Supersonic speed has brought a new hazard for jet-plane pilots: shooting themselves down with their own gunfire. Last week the Navy told how Test Pilot Tom Attridge was trying out the 20-mm. guns of a Grumman F11F-i fighter off Long Island. He put the airplane into a dive, speeded up to 880 m.p.h. and fired a four-second burst (about 70 rounds). Then he went into a steeper dive and fired another burst. As the last bullets left his guns, something struck and shattered his windshield. Pilot Attridge thought he had run down a bird. He headed for the Grumman base at Peconic River, but before he got there, his engine died. He crash-landed half a mile short of the field and broke a leg and three vertebrae.

Examination of the airplane proved that Pilot Attridge had hit no bird; he had overtaken and run down the fire from his own guns. A nonexplosive 20-mm. bullet (used in practice) had gone through his windshield. Another had hit the engine, a third had punctured the nose. If the projectiles had been explosive, Pilot Attridge would not have got home alive.

Navy experts explained that the bullets left the guns at 3,000 ft. per sec. Their speed through the air (muzzle velocity plus airplane's speed) was about 4,300 ft. per sec., but friction quickly slowed them, and gravity pulled them toward the earth. If the airplane had kept its original course, it would have passed by them, but its steepened dive made it intersect their down-curving path. When it hit them, they must have been moving so slowly that the airplane overtook them at a good fraction of its own air speed, which was about as fast as many a newly fired bullet.

This file is automatically generated by a robot program, so reader's discretion is required.