One of the objects, however, he would describe later as crescent-shaped, as shown in illustration at left.
In this interview with Ed Murrow:
"I assumed at the time they were a new formation or a new type of jet, though I was baffled by the fact that they did not have any tails. They passed almost directly in front of me, but at a distance of about 23 miles, which is not very great in the air. I judged their wingspan to be at least 100 feet across."
The shape drawn by [Kenneth] Arnold in the report submitted to Project Sign (later Project Blue Book) was of a heel-shaped object.
One was the Roswell Crash. Instances in which heel-shaped craft were reported.
UFO photograph taken over Phoenix, Arizona
More likely, he [Kenneth Arnold] witnessed experimental jets from German designs. In fact, the German Horton "Ho VI" was called a "flying parabola". This was an "extremely-high-aspect-ratio test-only glider". According to allwebco.co, "after the war, the Ho VI was shipped to Northrop for analysis."
The Northrop Flying Wing (YB-49) Prototype may be involved. "It was being tested at about the same time [Kenneth Arnold's sighting], and in the same area. It was crescent-shaped... (it's basically the GrandDaddy of Stealth) for lack of a getter(sic) term." - ezboard.com. The flying wing was a bomber that could carry 78,000 lbs. of bombs. - brooklyn.cuny.edu. Well, the YB-49 isn't crescent-shaped, it is wing-shaped. Mr. Squiggles, posts the same conclusion, but are misses the fact that a prototype of one of these flying wings was crescent shaped. I found one reference to an "E.A.P. canary crescent wing fighter jet".