A Group of Retired Engineers Built a Fully Functional Hovercraft From Lawn Mower Parts

The Silver Sneakers hovercraft looks like something a mad scientist might have built in a shed, which is appropriate, because it was built in a shed by a group of retired engineers with an average age of 74. The vehicle, named "Grasshopper," is constructed from three lawn mower engines, a plywood deck, a vinyl skirt salvaged from an inflatable kiddie pool, and a fan from a commercial kitchen exhaust system. It hovers six inches off the ground, can cross water, mud, snow, and moderately tall grass, and terrifies the local wildlife.

"The fan was the hardest part to source," said 78-year-old Harold Pincus, a former mechanical engineer who designed conveyor systems for a bottling plant. "We needed something that could move about 10,000 cubic feet of air per minute. Industrial fans cost thousands. Then my wife said, 'What about that thing they use to clear smoke out of restaurants?' Two weeks later, I had a used one from a Chinese buffet that was renovating. Cost me fifty bucks and a case of beer."

The three lawn mower engines perform different functions. Engine One (a 5-horsepower Briggs & Stratton from 1992) powers the lift fan, which forces air under the skirt to create the hover cushion. Engine Two (a 6.5-horsepower Honda from a riding mower) powers the thrust propeller, which pushes the Grasshopper forward. Engine Three (a 3.5-horsepower Tecumseh from a snowblower) powers a small generator that runs the lights, the horn, and the—and this is not a joke—the cup holder warmer.

"We are old," explained 72-year-old Rita Okonkwo, a former electrical engineer who designed the Grasshopper's wiring harness. "Our coffee gets cold. If you are skimming across a pond at 35 miles per hour in November, you want warm coffee. That is not a luxury. That is a safety requirement."

The Grasshopper took 18 months to build and cost approximately $2,300 in parts, most of which came from garage sales and online classifieds. The team's original budget was $500. "We blew through that on the first trip to the hardware store," Pincus admitted. "Fasteners alone were $200. We did not account for fasteners. There are 847 bolts in this thing. I counted."

The maiden voyage took place on a calm morning last spring on a farm pond owned by team member 76-year-old Walter Jensen, a former civil engineer. The Grasshopper rose off its trailer with a deafening roar, skimmed across the pond, climbed the far bank, mowed down a row of Jensen's wife's prize-winning petunias, and then hovered to a stop in a soybean field.

"My wife was not happy about the petunias," Jensen said. "But she admitted that the look on my face—pure, childlike joy—was worth a few flowers. Also, I replanted them. They survived. Petunias are tough."

Since then, the team has taken the Grasshopper to three local county fairs, where it draws crowds and occasional inquiries from law enforcement. The sheriff's deputy in Walworth County asked to see a registration. The team explained that hovercraft are not required to be registered because they do not make contact with the ground or water when in operation. The deputy was not amused, but he could not find a law that applied. The Grasshopper remains technically unregulated.

The team has been approached by a start-up company that wants to commercialize the design as a recreational vehicle for retirees. The team declined. "We do not want to build hovercraft for money," Pincus said. "We want to build hovercraft for fun. If you turn fun into a job, it stops being fun. Also, liability insurance would cost more than the hovercraft. Good luck to whoever tries to sell these to the public. But it will not be us."

When asked what advice they have for other retirees who might want to build their own hovercraft, Okonkwo was blunt. "Have hobbies," she said. "A lot of retired men sit on the couch and watch television and then they die. Do not do that. Build something stupid. Build something that might crash. Build something that makes your spouse roll their eyes. That is the secret to longevity: eye-rolls from your spouse. If they still have the energy to roll their eyes, you are still alive."

As for the Grasshopper's future, the team plans to enter it in the annual Oshkosh AirVenture "Oddball Aircraft" competition, where it will compete against a homemade helicopter made from bicycle parts and a flying saucer built by a man who believes he was abducted by aliens.

"We will lose to the flying saucer," Pincus predicted. "That guy has a better story. But our hovercraft actually works. And it has a cup holder warmer. That has to count for something."