The Engineering Book: From the Catapult to the Curiosity Rover: 250 Milestones in the History of Engineering

1944

Helicopter

Airplanes are fantastic. They let us fly through the air like birds. Modern airlines let us fly over the Atlantic and Pacific oceans in hours for reasonable prices.

But airplanes have one big problem: they require runways for takeoff and landing, and runways take up a lot of space. We are never going to be able to commute to work every morning in private airplanes because there can never be enough runways for this to be convenient.

What we need is a flying machine that can take off and land vertically, without a runway. And so the idea of the helicopter was born and first mass-produced in 1944 by Sikorsky.

From a layman’s standpoint, a helicopter seems simple enough—you just take an airplane propeller and spin it vertically rather than horizontally, right? But from an engineer’s standpoint, it is not nearly that simple.

If we take a propeller and spin it vertically, the engine wants to spin in the opposite direction just as fast as the propeller does. To counteract the engine’s rotation, engineers attach a long tail boom with its own propeller. The tail propeller needs power, so a long driveshaft transmits it from the engine. And the pilot needs to be able to control this boom propeller, so she or he does that with foot pedals.

Now the machine can rise straight into the air. How do engineers control its direction? And the rate that it rises or falls? A device called a swash plate can change the angle of the rotor’s wings as they are rotating. So it is possible to create more lift on the back side of the rotor than the front, tilting the helicopter forward and causing it to fly forward. Doing the opposite lets a helicopter fly backwards just as easily.

The idea of a heavy aircraft hovering in midair seems almost impossible. Yet mechanical engineers had made it happen.

The world’s first mass-produced helicopter, the Sikorsky R-4, returns from survey of South Pole waters.