Bertelsen's day job was the inspiration for his craft. He dreamt it up while trying to rush to his patients' homes—in colder seasons, a wintry mix always postponed house calls. To expedite the trip, he developed the Aeromobile 35B, an air-cushion vehicle (ACV) that glides above snow and water on a cushion of high-pressure air.
He didn't officially invent the hovercraft—Britain's Sir Christopher Cockerell did—but he was still a pioneer. Bertelsen was the first person to develop an ACV with a peripheral jet, which directs the high-pressure stream of air downward, rather than inward. His design provided better control than previous crafts because it could move left, right, forward and backward.
But his 15 minutes of fame quickly ended. By the early '60s, Britain was already off to a head start in ACV development because the country had secretly financed one of Cockerell's early projects in the late '50s. America couldn't keep up, and Britain soon became the Mecca of ACV design, rendering hovercraft pioneers in the U.S. invisible to both government officials and the general public.
Today, ACV interest throughout the world has mostly evaporated. Britain and Russia employ a few hovercrafts in their militaries, but the industry is largely confined to small pockets of hobbyists.
And while we're on the subject, Bertelsen has never liked the term "hovercraft."
"It's not meant to hover, it's meant to get places!" he says to me over the phone.
It's a question of semantics, but his statement reflects a deep frustration with the public's image of ACVs. Most people think of hovercrafts as elaborate toys, and not as functional vehicles. Bertelsen blames the craft's obscurity on last century's low fuel prices; since Americans didn't need to find an alternative to gas-guzzling cars, they ignored hovercrafts, which could have used less fuel than automobiles. The Space Race, which redirected most military funding to outperforming the Russians, pushed ACVs further into obscurity.
But as the hovercraft declined in popularity, Bertelsen became more and more interested in the craft and all of its air-vehicle relatives. It's the antithesis of capitalist economics—Bertelsen went where there was no market.single page
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.