9 - Aerodynamics in the Age of the Jet Airplane

Summary

We call the speed range just below and just above the sonic speed Mach – number nearly equal to 1 – the transonic range. Dryden [Hugh Dryden, well-known fluid dynamicist and past administrator of the National Advisory Committee for Aeronautics] and I invented the word “transonic.” We had found that a word was needed to denote the critical speed range of which we were talking. We could not agree whether it should be written with one s or two. Dryden was logical and wanted two s's. I thought it wasn't necessary always to be logical in aeronautics, so I wrote it with one s. I introduced the term in this form in a report to the Air Force. I am not sure whether the general who read it knew what it meant, but his answer contained the word, so it seemed to be officially accepted …. I will remember this period [about 1941] when designers were rather frantic because of the unexpected difficulties of transonic flight. They thought the troubles indicated a failure in aerodynamic theory.

Theodore von Kámán (Aerodynamics, 1954, p. 116)

The morning of Tuesday, October 14, 1947, dawned bright and beautiful over Muroc Dry Lake, a large expanse of flat, hard surface in the Mojave Desert in California. At 6:00 a.m., teams of engineers and technicians at the Muroc Army Air Field began to prepare a small rocket-powered airplane for flight. Painted orange, and resembling a 50caliber machine-gun bullet mated to a pair of straight, stubby wings, the Bell X-I research vehicle was carefully installed in the bomb bay of a four-engine B-29 bomber of World War II vintage. At 10:00 a.m. the B-29 took off and climbed to an altitude of 20,000 ft. As it rose past 5,000 ft, Captain Charles (“Chuck”) Yeager, a veteran P-51 pilot from the European theater during World War II, struggled into the cockpit of the X-I.