Old World War II training films and propaganda films are can be entertaining as well as informative. This 23-minute semi-documentary from the ’40s showcases the unique turbosupercharger system on the B-17 and B-24 bombers as well as selected fighter planes. Boost in the intake manifold was needed to help the planes get high enough to avoid detection, anti-aircraft ground fire and opposing attack fighter planes. Using animation, the film demonstrates just how much power the engines were losing at higher altitudes. The turbosupercharger solved that problem.
In very patriotic, and sometimes infantile language (“cramming air into the engine”), the narrator walks the viewers through the history of the plane and development of the turbosupercharger system. There’s even footage of the system being tested on the back of a truck at Pike’s Peak. At sea level, the engine made 400 horsepower naturally aspirated. Atop the mountain, the power dropped to 265. But add the turbosupercharger and it climbed to 410 horsepower.
Very simple animation is used to explain the system, which boasts two boost mechanisms. First, there’s a gear-driven supercharger that helps the plane get up to mid altitudes. When needed, the exhaust-driven turbocharger sends forced air through an intercooler to the supercharger. The pilot controls the boost levels with a crude throttle valve that acts as a wastegate.
Much of the film reverts to classroom training footage, such as maintenance checklist in the hanger and component rebuilding back at the shop. Still, it’s fun way to kill a few minutes and see a massive turbo in action.