In the first raid on Pearl Harbor, U.S. anti-aircraft gunners had bitter proof of a once arguable proposition: that the U.S. needs hub-to-hub anti-aircraft protection for its vital points. For that protection they still had to wait on U.S. production. But last week, as the need became urgent, they had evidence that the U.S. was finally catching up with the anti-aircraft parade, perhaps ready to jump into the van. Anti-aircraft men were notified that soon they would have a gun that would shoot as high as military planes can now operate.
Dour, taciturn Brigadier General Gladeon M. Barnes, of the Army's Ordnance Department, announced that a civilian plant was being tooled up for production of the new piece. The sky-prodder is a 4.7-in. caliber cannon that will hurl shells more than 40,000 feet upmore than seven and a half miles. The range is neither theoretical nor guesswork. An adaptation of an earlier gun, the 4.7 has already been thoroughly tested.
The new weapon will be a great improvement on the pre-war standard U.S. anti-aircraft piece: a 3-incher with a top altitude of 15,000 to 18,000 feet. Next came a 90-mm. gunin its turn quickly outmoded by aircraft designers. Now the race between gun and airplane should be closer. German and British aircraft designers are also out after higher operating altitudes. The top-flight aircraft of 1942 will still be able to crawl up beyond the reach of the new 4.7's threatening fingers. But their pilots won'tuntil aircraftmen design a suitable (i.e., supercharged) cabin. Without more aid and comfort than oxygen can give, top operating altitude for the man at the controls is around 30,000 feet.