General Hap Arnold 
General Henry H. (Hap) Arnold, 1886-1950, was chief of the Army Air forces during WWII, and in 1942 received the title of Commanding General of the Army Air Forces for the duration of the war. During his command, the air forces grew from 22,000 personnel and 3,900 planes to 2,500,000 personnel and 75,000 planes. Beyond this understandable wartime growth of manpower and technology, Arnold was also an constant and powerful advocate for an independent air wing of the US military force, and is often considered the "Father" of the USAF as an independent service. General Arnold suffered a heart attack in 1945, and was involved with Air Force affairs only in a much reduced consulting role until his death in 1950.  General Arnold's only UFO-related activity may well have been the concern over the so-called "foo fighter" phenomenon during the war, which occurred in both the European and Pacific theatres. These seeming devices concerned the highest authorities as possibly being enemy weapons capable of interfering with US bombing runs. Arnold and Secretary of War Henry Stimson were greatly worried about what these things could be. Stimson's scientific advisor, Professor Edward Bowles of MIT, had a hotshot young PhD, who also happened to be a pilot. David Griggs was therefore assigned, under Arnold's authority, to go to the European front to investigate the phenomenon as he could. Griggs' investigation later took him to Japan as well. Griggs wrote reports which have never been released. Modern UFOlogists have attempted to link General Arnold with a few UFO-related stories, including an alleged 1947 "crash" in the United States. To this writer's knowledge, there have been no credible smoking guns to document such claims. General Arnold was one of the forceful individuals who developed the Air Force's secretive RAND corporation/ thinktank, which was called in by Project SIGN for consultancy, but there is no evidence that RAND was primarily interested in UFOs, and the RAND consultant to SIGN, engineer Jimmy Lipp, is known to have despised them. RAND was very interested in guided missiles and what eventually became ICBMs, and this interest is what the famous RAND study of the possibility of a "World-circling Spaceship" was all about. General Arnold was interviewed about flying discs on July 7, 1947 as many technological and airpower heavyweights were at the time, and remarked that the disks could be a US technical development not yet perfected. As this is exactly what the Collections division of Pentagon air intelligence thought at the time, Arnold's remark is rather explainable.