How the 747 Got Its Hump
In the evolution of the airplane, Darwinian principles have applied unevenly.
- By Bill Sweetman
- Air & Space magazine, May 2003
(Page 2 of 6)
Trace the line back and you will find an airplane that looks new and revolutionary—only to find that its own design is usually the happy combination of many strands of previously existing DNA, with results that the designers themselves never quite foresaw until the airplane was complete.
Most large commercial jet aircraft—even those designed by arch-rivals—look like members of the same family. Their engines hang on pylons, in front of and below their swept-back wings. The landing gear is in exactly the same place: hinged behind the rear wing spar and folding inward to stow behind the wing. The wings all have lift-boosting devices—flaps—across their leading and trailing edges.
All these airplanes carry the DNA of a common ancestor: the Boeing 367-80, also known as “Dash 80.” That Boeing 707 prototype, in turn, emerged from a tumultuous nine-year process as the third in a sequence of significantly different airplanes, the first two being the B-47 and B-52 jet bombers.
In 1945, after Allied armies had secured German research files, Boeing aerodynamicist George Schairer unearthed a goldmine of data the Germans had compiled on swept wings. Boeing promptly junked its Model 432 straight-wing jet bomber design in favor of what would eventually become the B-47, which shared its new features—“bicycle” landing gear, swept wings, and pod-housed engines—with a Junkers design, the EF 150, that had never been built. (Unknown to Boeing, the EF 150 designers had been taken to Russia to complete their work; see “The Rise and Fall of the East German Aircraft Industry,” Feb./Mar. 1996.)
The Strategic Air Command learned to live with the B-47’s deficiencies and vile habits because the Stratojet was faster than most Soviet fighters. Too fast to land safely, B-47s trailed two braking parachutes. Underpowered, the bombers were fitted with booster rockets for takeoff. Short on range, Stratojets were refueled in flight by a fleet of hundreds of SAC tankers.
Boeing corrected many of the B-47’s problems by improving the wing and engines in its next heavy bomber design, which could have fit the intelligent design theory had it led to a commercial jet or transport. But its conceptual design phase encompassed a weekend marked by an atmosphere of crisis in a hotel room in Dayton, Ohio: the B-47 follow-on was in trouble.
In October 1948, three senior Boeing engineers had a bad-news Friday meeting at Wright-Patterson Air Force Base in Dayton. Weary of problems with the engine installation on Boeing’s new heavy bomber, the Air Force made it clear that the project was all but dead.
But two other Boeing engineers were also in Dayton and working on a study for an improved B-47-size medium bomber with a better wing design and better engines. Over the weekend, the Boeing team projected that airplane’s characteristics into a larger, eight-engine design. George Schairer bought balsa wood and tools at a hobby shop, and by Monday, the Boeing team had a model to accompany its presentation. The project won a reprieve, and Schairer posed for a publicity photograph with the model in his hands. It is quite recognizably a B-52.