March 2000

March SN Contents

People

Dr. Bertelsen’s Hovercraft

by Clare Coppa


Dr. William Bertelson (L)
and Son Bill Bertelsen

Listening to ASTM member Bill Bertelsen describe the hovercraft invented by his father, William Bertelsen, M.D., brings to mind the flying cars on the Jetsons.

Dr. Bertelsen’s Aeromobile-2000 has a hover-ring, instead of tires, and flies inches above ground on a cushion of air. One wonders if advanced models will be parked in home hoverports of the future, nixing the problem of snowbound roads.

British hovercraft have ferried aircraft, cars, and passengers across the English channel since the 1960s. Typically, gas-fueled hovercraft move 35 mph (56 km/h) above ice, calm water or flat land. Hills, headwinds, and rough surfaces challenge land travel, but a proliferation of Web-connected manufacturers and enthusiasts continue to expand their capabilities.

An aeronautical and astronautical engineer, Bill Bertelsen provides occasional technical assistance to Dr. Bertelsen and his company, Aeromobile, Inc., Rock Island, Ill. (www.aeromobile.com). “Dad’s patented tilting Gimbal fans offer superior maneuverability,” he says. “Each unit provides both lift air and 360&Mac251; directional thrust. My Dad’s control system makes this one different than some of the other air cushion vehicles that have been used over the years. We think we’re on the threshold now of something that will have a lot of utility.”

Bertelsen is vice chairman of ASTM Subcommittee D30.09 on Sandwich Construction. He invented the Hydromat panel test system used in new ASTM D 6416, Standard Test Method for Two-Dimensional Flexural Properties of Simply Supported Sandwich Composites, and developed the standard with ASTM Committee D30 on Composite Materials. “My Dad and I think the ASTM test method will play a role in air cushion development. Sandwich construction offers the possibility of weight savings on the hull for air cushion vehicles as well as boat hulls. The prototype is basically a steel tube and aluminum structure but we could save a lot of weight with composite.”

In the 1870s, Sir John Thornycroft birthed the idea of early hovercraft and hydroplanes with experiments on his aunt’s lily pond. “Air car” theories surfaced, but Sir Christopher Cockerell is credited with the first unmanned working models in the 1950s. As Cockerell designed hovercraft in England, Bill Bertelsen watched his father invent air cushion vehicles in Illinois: “I can recall helping Dad measure base pressures when I was just seven or eight years old. I’d mark the manometers when he’d fire up one of his machines. We’d first test the machine inside the workshop and then take it over to the high school football field.”

A general practitioner, Dr. Bertelsen sought alternative travel when impassible rural areas slowed his housecalls. He flew his first man-carrying hovercraft in 1958, eight months earlier than Cockerell. “Dad is an air cushion vehicle pioneer,” says Bertelsen. “He was the first one to fly a man-carrying air cushion vehicle. It was developed more or less simultaneously in England by Sir Christopher Cockerell and my Dad over here. In fact, one of my Dad’s early machines is in storage at the Smithsonian. There were some independent efforts going on in different countries. Nobody knew about the work going on, so there was some overlap.”

Bill assisted with several of his Dad’s 18 models—good practice for his present position as chief test engineer with Gougeon Brothers, Inc., Bay City, Mich., an epoxy-resin formulator of general purpose laminating products. In materials testing 17 years, he creates methods and equipment to test epoxy and its composites.

Dr. Bertelsen never flew to housecalls, but his vision may be similarly realized; the U.S. Coast Guard is considering the A-2000 for ice patrol and rescue. “Dad will celebrate his 80th birthday in May,” says Bill. “He is working part-time as an emergency room physician and continues to refine the Gimbal fan.” It is anticipated that the A-2000 will generate interest and income for another of Dr. Bertelsen’s innovations, a high-speed shuttle Aeroduct transportation system. “It will open up a lot of possibilities for efficient surface travel,” he continues. “I hope to be involved with that at some point.” //