The story of the prototype 707.
- By R.G. Thompson
- Air & Space magazine, May 1987
(Page 2 of 5)
Work got under way virtually the morning after the meeting. The project was code-named 367-80, to encourage competitors to think Boeing was having its 80th go at a variation of the Model 367, the company’s designation for the KC-97 prototype. In fact, Boeing’s preliminary design for a jet transport had been in the works since the late 1940s. Construction of the prototype began in a walled-off corner of Boeing’s Renton, Washington plant in November, and the rollout took place in May 1954—just 18 months later. The next year, Douglas decided to skip the prototype stage and go ahead with production of a four-engine jet called the DC-8.
To those who thought the Douglas DC-7 and the Lockheed Super Constellation were immense, Dash 80’s 128-foot fuselage and 130-foot wingspan were shockingly huge. But it looked like a pretty ordinary piece of work to the folks at Boeing—not that large compared to the B-52, and perhaps even a bit conservative in wingspan.
It was not the size but the design of the wings and engine mounts that gave Boeing its most important lead over its competitor. The 35-degree sweep of the wing and tail had been established through research that included a series of flights in a Bell L-39, which was a Bell P-63 with its wings swept. The same angle had been used on both the B-47 and B-52. With this angle, Dash 80 turned out to be 20 mph faster than the DC-8, with its 30-degree sweep.
The practice of mounting engines in pods on pylons below the wing began in 1947 with the B-47. Suspending the engines from pylons left room in the wings for fuel tanks. And in a crash landing, a pod could break away without damaging a wing or rupturing one of its fuel tanks. Unlike the bombers, which had their engines in pairs, Dash 80’s design called for a single engine in each pod, so if an engine blew up, it wouldn’t damage its neighbor. The arrangement also provided a more even distribution of the engine’s weight and allowed for lighter wings. And the pods opened up so that airline mechanics had easy access to each engine.
It was an impressive design, but not perfect: Dash 80 had some bugs in its tail assembly and landing gear, and test pilots Johnston and Richard “Dix” Loesch, along with engineer James Gannett, were responsible for shaking them out. Boeing could not have brought together three more diverse personalities. Chief pilot Johnston had all the swagger you expect in someone named Tex, though he could be reserved when he talked about airplanes. Gannett was his exact opposite, wiry and quiet. Loesch was the most reflective of the trio and easily the most emotional about the project and his memories of those days. But then, it was his luck to catch some of Dash 80’s wildest rides.
Landing an 80-ton airplane at speeds of 150-mph and less had been done before. But using only the wheel brakes to get one stopped within 6,000 feet on a wet or icy runway hadn’t, and that was as much room as the largest airports of the day had to offer. Large military aircraft landed on 10,000-foot runways with the assistance of a drag chute, an impractical system for airline operations.
Faced with these constraints, Boeing designers gave Dash 80 thrust reversers to accomplish what the reversing propellers on piston-engine aircraft did to reduce ground roll distances after landing. After evaluating three final candidates, the designers chose the folding W-shaped design that is now seen on the aft end of almost all jet engines. They also came up with a new version of the conventional tricycle landing gear, one that gave test pilots and engineers many headaches.
On the eve of the scheduled maiden flight, the left main gear collapsed after some taxiing tests. “Well, now is the time to learn these things,” Johnston said as he stepped out of the airplane. Dash 80 lay on the ground like an exhausted bird. At least the gear had performed as advertised: it broke away without damaging the wing or the fuel tanks. Dash 80’s first flight was postponed while engineers beefed up the gear structure and healed minor wounds.