A NASA Engineer Invented the Super Soaker While Trying to Build a Better Refrigerator

US4591071 was granted to Lonnie G. Johnson on May 27, 1986. The title is "Squirt gun." It is the patent behind the Super Soaker, and it came out of a serious piece of thermodynamics research that Johnson was doing in his spare time.

Johnson is a genuine rocket scientist. He served in the Air Force, worked on the nuclear power source for the Galileo mission to Jupiter at NASA's Jet Propulsion Laboratory, and worked on the Cassini mission to Saturn. He holds well over a hundred patents.

In 1982 he was working at home on an idea for a heat pump that would use water as its working fluid instead of chlorofluorocarbons like Freon, which were then being identified as a serious threat to the ozone layer. Testing a prototype nozzle, he attached it to his bathroom sink and let it go.

The jet of water shot across the bathroom with startling force. Johnson's reaction, by his own account many times since, was not about refrigeration. He looked at the stream and thought that it would make a fantastic water gun.

Why it works

Ordinary squirt guns of the era used a simple trigger-driven piston: each pull of the trigger pushed out one small squirt. Range was a few feet, and volume was trivial.

Johnson's design separated the pumping from the firing. The user works a hand pump to compress air inside a sealed chamber, storing energy. When the trigger opens the valve, that stored pressure drives water out continuously in a heavy, long-range stream, rather than in a single weak pulse. It is a pressurized-reservoir system, essentially the same principle as a garden sprayer, applied to a toy.

The difference in performance was not incremental. It was a different category of object.

Seven years to sell it

Having the patent did not mean having a product. Johnson spent years pitching toy companies without success, and at one point looked into manufacturing it himself, only to find the tooling costs prohibitive.

The turn came in 1989, when he demonstrated the prototype to executives at the Larami Corporation. The often-told version of the meeting is that Johnson opened a case, pumped the device, and fired a stream of water clear across the conference room — at which point the negotiation was effectively over.

Larami released it in 1990, first as the Power Drencher and then, renamed, as the Super Soaker. It was the best-selling toy in America in 1991 and has generated, by widely cited estimates, well over a billion dollars in sales. Johnson's royalties reportedly ran into the tens of millions.

What he did with the money

Johnson used the proceeds to fund his own research laboratory in Atlanta, where he has spent the decades since working on energy technology — including the Johnson Thermo-Electrochemical Converter, an attempt to convert heat directly into electricity at high efficiency, and work on solid-state and advanced batteries.

Which means the arc is unusually neat: an engineer trying to build a cleaner refrigerator accidentally invented a water gun, and used the water gun money to go back to work on clean energy.

See the original

The full text and figures of US4591071 are on patents.us.