The KB-3 was derived from the 1970 KB-2 and specifically designed to comply with the US FAR 103 Ultralight Vehicles rules, including the category's maximum empty weight of 2540NaN0. The aircraft has a standard empty weight of 2500NaN0. It features a single main rotor, a single-seat open cockpit without a windshield, tricycle landing gear and a twin cylinder, liquid-cooled, two-stroke, dual-ignition 640NaN0 Rotax 582 engine in pusher configuration.
The aircraft fuselage is made from bolted-together aluminum tubing. Its 221NaN1 diameter rotor has two blades. Factory available options included a main rotor pre-rotator, a rotor brake and an instrument package. Fuel capacity is and is housed in a combination pilot seat/fuel tank.
Due to its small size and light weight the KB-3 is easy to transport by trailer and can be set up to fly in ten minutes.