Two years ago, NASA Engineer Lonnie Johnson was working on his latest creation — a cooling pump that used water instead of Freon. He had a custom nozzle hooked up to his bathroom sink, and when he turned the water on, it fired a stream across the room. He immediately thought, “This would make a great water gun!”
Lonnie molded a plastic air pressure chamber and water reservoir inside. To fire the gun, you pumped air into the pressure chamber with an external piston, then pushed a release valve, allowing some of the compressed air to escape, which shoots water out of the barrel at high velocity.
“My 6 year-old daughter and her friends loved it!”