On Friday, June 4, 1948, Air Force test pilot Glen Edwards felt slightly frustrated.Maj. Daniel Forbes Jr. was perturbed, too. With Forbes as the pilot and Edwards as his co-pilot, they tested a jet-propelled, heavy bomber prototype known as YB-49 No. 2. The YB-49 was a Flying Wing with eight turbojet engines and four vertical stabilizers. It had no fuselage or tails. For all of its sleek design, the YB-49 sometimes proved difficult to control i…