Inventions Ahead of Their Time: The Helicopter
CREDIT: Leonardo da Vinci, via Wikimedia Commons
Leonardo Da Vinci is one of those figures whose genius defies easy definition. It would be very nice if we could box him up as the man who painted the Mona Lisa, throw his face on a stamp and be done with it. But it's not that easy, since also made significant contributions to the fields of anatomy, botany, and cartography, to name just a few.
Da Vinci even imagined a curious craft that he called an "aerial-screw." It looked a bit like a ship, but was meant to sail straight up into the air rather than across water, making it the first known design for a helicopter . The sail was to be made of linen and wrapped in a vertical spiral around a central column. Four handles extended out at the base of the column and when pushed, they would rotate the entire structure. As the sail turned it would bore into the air like a screw. Da Vinci reasoned that with enough force, the sail could compress the air beneath it and lift the craft into the sky.
Although Da Vinci didn't leave behind any models to be tested, his estimations on the energy demands of his invention were probably way off. Four men alone not be able to turn the shaft fast enough to get off the ground, according to flight historian Judy Rumerman. Nor did his sketches include a secondary rotor necessary for directional control.
Although Da Vinci's sketched his "aerial-screw" in 1483, the notebook wasn't published for another three centuries, and it took until the 20th century for people to get serious about building a functional helicopter.
In the 1930's a handful of aerial engineers, with Heinrich Focke and Louis Bréguet leading the pack, made encouraging progress, experimenting with the number of rotor blades and different ways to reduce structural vibration. A lot of the designs went up, but only for a few seconds. And they were very difficult to control.
In 1931, Igor Sikorsky, a Russian engineer who already had his own aviation company and a wind tunnel to play with, patented a single rotor helicopter. By 1941, Sikorsky had a helicopter that could stay in the air for over an hour and a half, according to historian Dwayne Day. That was evidence enough for the U.S. army, which quickly put in an order and permanently adopted the helicopter into its fleet .
In the end, a lot of people did the work, but who gets credit is still up for grabs.
This article is part of an ongoing series about inventions that arrived before the public was ready to accept them. You can read the rest of the series here.