One evening last week Britain's No. 1 test pilot shut himself into what was probably the most advanced piece of air machinery ever to get beyond the blueprinting stage, and took off into the darkening sky. The pilot was Captain Geoffrey De Havilland, 37, crown prince of one of aviation's few dynasties. His father, Sir Geoffrey, heads the De Havilland Aircraft Co.; his younger brother John was killed (1943) in the collision of two planes. Since 1938, Captain Geoffrey had made every first flying test of De Havilland's aircraft.
The new plane was the DH-108, a jet-propelled, tailless aircraft shaped like...