Amjet400 Amphibian Design Unveiled

Talk about making a splash.

Amjet unveiled a remarkable new aircraft design here on Monday-an all-composite, forward-swept-wing, single-engine jet that happens to be an amphibian.

The Amjet 400 is the brainchild of Dr. Leonard Gioia, a 33-year member of the staff of Cape Canaveral Hospital and a 3,500-hour, instrument-rated, multi-engine pilot. In 1974, Gioia bought a SIAI-Marchetti Riviera amphibian. "It took off at 90, cruised at 90 and stalled at 90," Gioia recalls. There must, he thought, be a better way to build a waterborne aircraft.

Gioia initially refined the design with the help of Dr. Donald Ritchie, chairman of the department of aeronautical engineering at Embry-Riddle University, and NASA aerodynamicist Dick Whitcomb. Unable to find a sponsor for development, Gioia shelved the project and patented the design in 1987.

The design would probably have stopped there had it not been for Gioia's four adult children, who persuaded him to revive the project last year. Dr. Gioia asked aircraft designer Roy LoPresti, a personal friend, to perform a preliminary design, performance and sizing study on the aircraft, resulting in the current Amjet 400 design.

The key to the Amjet 400's performance is a radical hull design that eliminates the drag of the step, hard chines and vee-bottom of a conventional seaplane. Basically, the Amjet has a tunnel hull formed by two sponsons, like a racing hydroplane-"Miss Budweiser with wings," says Dr. Gioia. The sponsons give the design excellent water stability and accommodate the retractable landing gear. In Amjet's patented design, the rear part of the sponson moves up and back for water operations, creating a step to unstick the body from the water. Air flows through the gap between the front and rear parts of the sponson, venting into the low-pressure pocket behind the step and providing a smooth, low-drag lift-off.

The Amjet is not designed for open-ocean operations, but it can take off "anywhere that you can get an 18 to 20 foot speedboat to do 50 kt," says Gioia. The hull draws only 18 inches of water, and composites eliminate the corrosion problems that plague marine aircraft.

LoPresti's study defined a 448-kt aircraft with accommodation for a pilot and six passengers. Power is provided by a 3,650-pound-thrust AlliedSignal TFE731-20, and large Fowler flaps provide a modest 70-kt stall speed. The 8,700-pound airplane should have a range of more than 1,230 nmi.

Dr. Gioia's company is seeking financial support for an 18- to 24-month program to fly a prototype of the Amjet and demonstrate its new hull technology.

By Bill Sweetman