Why DOES the 747 have a hump?



I never really understood how colossal that behemoth plane, the 747, is until I stood next to the front landing gear and looked up. I was at the press conference for the opening of " America by Air," a new exhibition opening Saturday at the
National Air and Space Museum.

Hanging on the wall is some 36 feet of the front fuselage of a 747; the entire airplane is 231 feet long. You can also climb up several flights of stairs and take a peek into the cockpit. You can see the controls and the hundreds of instruments.

For such an incredibly huge airplane, it's odd that it's so cramped in there--smaller than my cubicle! Seating for the pilot, co-pilot and navigator is really tight. Sitting hour after hour in that tiny cockpit can't be much of a joy ride.

So what's up with that camelback hump on a 747?

Pan Am head Juan Trippe, a key customer for the 747, told Boeing, the manufacturer, that he doubted the aircraft would be commercially viable as a passenger plane. So he insisted that it be easily convertible to a cargo plane. That meant a nose that could be opened and closed on a top hinge. And a nose that would open and close would be an impossible place for the cockpit.

For one thing, having all the wiring and control cables between the cockpit and the plane bending back and forth as the nose opened and closed would have been a very bad idea. So the cockpit was put up behind the nose. To make room for the cockpit, and to keep the plane maximally aerodynamic, there had to be a hump. Later versions of the 747 extended the hump farther back and made room for more first-class seats.

As for why the camel has a hump? That's another story.

(Courtesy of Eric Long/National Air and Space Museum)


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