Plane: B-29 Superfortress

The B-29 Superfortress was the last kid airplane to matter. Built by Boeing (in those days Boeing was primarily a military manufacturer), it was the big brother of the company’s earlier B-17 Flying Fortress (that plane was the star of Memphis Belle and, somewhat unfairly, any other movie you’ve seen about World War II).

The B-29 was a huge plane at the time. Compared to the B-17, it was twice as large, could fly 60% farther, and could carry 3 times as much. It’s comparable to today’s Boeing 737 and Airbus A320, the kind of plane you generally fly domestically.

The earlier Flying Fortress got its name from having so many attached machine guns (13) that it looked like a fortress. The B-29 kept the name for marketing purposes, but was as much a porcupine. Guns aren’t intersting, but their presence proves the B-29 was designed in a low-speed world: if planes fly at 600mph, their combined speed of 1200 mph is so fast that guns aren’t useful.

The B-29 is (in)famous as the plane that ended WWII. “Enola Gay” and “Bockscar” were B-29s that dropped the atomic bombs on Japan, thereby proving that such large planes were feasible and that 1940s pilots picked terrible names for airplanes.

The age of the propeller plane was past. There were 12,000+ B-17s but just under 4,000 B-29s. Boeing would sell the Air Force a further upgrade of the Superfortress (more powerful engines and various improvements) as the B-50, but only made 370 that flew in support roles until 1965.

Amusingly, the B-29’s last gasp was in China. Over the course of WWII 3 B-29s landed in the USSR. They reverse engineered every piece to make the Tu-4. It weighed more and performed worse than the original B-29 because every imperial metal thickness was rounded up when converted to metric. The Russian manufacturer built 847 Tu-4’s and sent some to its ally China where they flew until 1988.

The Jet Engine: a Transmogrifier

How jet engines work is fascinating. Unfortunately for me, I don’t really understand how they work. Which is fortunate for you, because you don’t care about how they work. So let’s examine how they changed the plane design game.

A recap: before jets, planes used piston engines (the same kind that power cars). The engines were much larger (the P-51 Mustang (c. 1944) had 12 cylinders producing 1390 horsepower, whereas a 2011 Ford Mustang maxes out at 8 cylinders producing 550 hp). In cars, the rotational energy coming from the engine spins wheels. In a plane, that energy spins propellers that push air backwards and the plane forwards.

In jets, the air being pushed backwards is the same air reacting with the fuel. This creates a lot more power: about 4x as much per pound compared to a piston engine. (This reaction also spins a turbine, which also does some of the pushing and continues the reaction. I’m not completely clear, but it seems to help).

Plane designers had a new toy. It was far more powerful, and like Wile E. Coyote with an Acme Rocket, they were eager to use it. And about as successful: this new technology had its own problems (they were flaky and dangerous) and revealed latent problems in existing designs (what’s aerodynamic at 300mph is clunky at 600mph).

Transition to the Jet Age

You’re not a plane expert, but you see differences in planes. You can tell the Wright Flyer (c. 1903) from a World War II plane (c. 1939-1945) from a modern plane (c. 1947 onwards). Don’t believe me? Take the quiz [Here is a link to a quiz]. You’re not psychic, you’re responding to differences in the wings, engines, size, etc. Planes from the same age look similar (but not the same) because they’re designed with similar technology. It’s the same with people: you can tell if a person is a kid or an adult, even if you mistake a 12 year-old with a 13 year-old or a 35 year-old with a 40 year-old. WWII planes are kids; modern planes are adults.

In humans, all of the changes (height, surprising hair, glands) are side effects of increased hormone (testosterone or estrogen) development. In planes, all the changes are side effects of one technological improvement: the jet engine. This more powerful powerplant made planes faster, sleeker, bigger, and more comfortable.

We’re going to look at two planes (the B-17 and the B-47) made in the same country (America) by the same company (Boeing) for the same purpose (Strategic Bomber), only 12 years apart (1935 vs. 1947). But the B-17 is a kid and the B-47 is an adult not fundamentally different from the planes we fly in today. They are the endpoints of the Transition to the Jet Age, a.k.a. Plane Puberty.