Secrecy of war and the fast development of new planes are hushing many a record performance that would be front page sensations in normal times. One of the most amazing feats was that of an American-built medium bomber that set a world record recently by diving at 560 miles an hour - better than nine miles a minute. The event was not publicized until some time afterward. Three men were aboard the Martin “Baltimore” when it roared down in a 65-degree power dive at not much less than the speed of sound. A record crossing of the Atlantic by another U.S.bomber in eight hours, 23 minutes, similarly went almost unnoticed. An army flier took a P-34 Republic pursuit- interceptor plane from Lowry Field, Denver, to New York at 6 1/3 miles a minute - 1,800 miles in four hours, 43 minutes.