While modern commercial aircraft can be hard to tell apart, there’s no mistaking the majestic shape of the Boeing 747. Its distinctive hump containing the cockpit and a second-floor seating area ahead of the wings was, and still is, unlike any other airliner. But why is it there? Does it serve any purpose besides making first-class fliers feel more important?
The 747 has an illustrious reputation as the “Queen of the Skies,” flown by everyone from Pan Am to Iron Maiden (until the band chopped up its plane for souvenirs). The controversial gift from Qatar to President Donald Trump is also a 747. But when it comes to its distinctive hump, the answer comes down to a far less prestigious purpose: hauling cargo.
The cargo version required a nose door that opened upward for easy loading and unloading. The only problem with this design was that the cockpit also needed to be in the front, since it helps if the pilots can see where they’re going. Boeing’s solution was to put the cockpit on top of the main fuselage rather than within it. This avoided the hassles of having to run the 747’s extremely complex wiring and linkages to flight controls through the hinged section, not to mention the flight crew’s stuff falling all over the floor anytime the cargo hatch was opened.
A backup plan
Today, with hindsight being 20/20, we know how the Boeing 747 revolutionized air travel. But that was anything but a sure thing back when it was still on the drawing board in the mid-1960s. Boeing had high hopes for a different airliner: the supersonic 2707, intended to compete with the Concorde. Both the Concorde and the 2707 were intended to revolutionize passenger travel with supersonic speeds, relegating the 747 jumbo jet to relatively low-speed cargo duty.
Pan Am CEO Juan Trippe believed in the 747, but he also believed in a supersonic future for passenger air travel. He was willing to buy 25 Boeing 747s for the airline, but only if they could be easily converted from passenger to cargo duty if supersonic travel took off and subsonic passenger service dwindled. This would make sure his significant investment in the 747 could still be put to good use, and not go to waste.
The easiest way to accomplish this was to move the cockpit to a second level of the aircraft, leaving the lower level free for a full-height cargo door that swung up when open. This design was part of a rejected military cargo plane proposal just a few years earlier, which Boeing could now put to good use. The upper-level cockpit remained on passenger versions of the 747 as well, making it easier to convert them into cargo planes as Pan Am demanded. Ironically, Boeing does not actually convert existing passenger planes into cargo planes, despite this being an original design requirement.
The hump enlarges
While the cockpit was the only area required above the cargo door, aerodynamics dictated the now-iconic teardrop shape behind it that blended back into the main fuselage. Having only the cockpit sticking up above the rest of the fuselage would have created too much drag, so the area behind it was blended smoothly back into the body of the plane. This created the teardrop shape we know and love today. Boeing then took inspiration from the 377 Stratocruiser of the 1940s, turning this area into a bar and lounge. This was later replaced with additional passenger seating, often first class, as demand increased.
Boeing added the original hump exclusively for aerodynamic purposes, but once it saw how the resulting interior space could be put to good use, it looked into stretching the hump over the wings and central fuselage on future models. Boeing had to figure out how to connect the hump from the front section to the central wing box section for the 747SP, a rare variant with a short fuselage intended for extended-range flights. Standard models contain the hump entirely within the front section, so this required a bit of re-engineering.
Once that was done, Boeing used the same techniques to elongate the hump on standard models, starting with the 747-300. This continued to future models like the 747-400 and beyond, augmenting the 747’s iconic shape into what we know and love today. The Queen of the Skies may be retiring, but she will always be fondly remembered for her place in aviation history.
