No manned supersonic aircraft fought in World War II. In fact,
the first manned supersonic flight had to wait until October 1O,
1947, when the Bell X-1 rocket plane exceeded the speed of
sound. Nevertheless, the German V-2 ballistic missile penetrated
the hypersonic range early in the war. The first V-2s fell on
England in 1944 at speeds of Mach 5 (3400 mph) and were
completely invulnerable to fighter interception. When the Allies
captured the V-2 test facilities at Peenemunde on the Baltic,
they discovered, to their surprise, a 0.4-meter (1. 2-foot) wind
tunnel that could attain Mach 5 on an intermittent basis. In
addition, a 1-meter (3.3-foot) continuous-flow tunnel capable of
Mach 10 was under construction for the purpose of testing the
German A-9 and A-10 intercontinental ballistic missiles destined
for the bombardment of the United States. Hypersonic flight had
thus leapfrogged the supersonic range. There was much debate
about whether ballistic missiles would ever amount to much in a
military sense, but