The target of research thrust was to test a configuration of features that would be of particular interest for an Army observation airplane. These features were: first, good pilot and observer visibility; second, a good utility cargo volume; third, STOL performance; fourth, unprepared field operation; fifth, a good cruising speed; and sixth, lower cost and simpler maintenance than a helicopter. To meet these targets, the airplane was laid out as a small pusher with an extended shaft from a turbine engine driving a ducted propeller. The prop duct was integrated into the tail surfaces. The landing gear had four small wheels located in a pair of sprung skids. The tapered cantilever wing was mounted high on the fuselage and designed to achieve a highlanding and takeoff lift coefficient, along with low drag in cruise. To achieve this goal, the wing was provided with an electrically operated mechanism to change the airfoil camber in flight.This feature was combined with distributed suction through perforationsin the top skin to delay turbulent separation of the boundary layer at high lift coefficients.

The feasibility of these unconventional features had previously been tested on a piston-powered testbed, the XAZ-1. This airplane was in essentially the same configuration as the "Marvel" and was referred to as the "Marvelette." With this background, the "Marvel" was successfully used for about 100 hours of testing and research flying. The program was then discontinued and the "Marvel" was placed in storage until 1982.

In early 1982 the initial modification of the "Marvel" was undertaken under Brico contract to substantially meet the above requirements. It was felt the "Marvel" was a good starting point because it was originally configured around similar requirements. In addition, the "Marvel" was constructed almost entirely of fiberglas reinforced plastic in order to achieve smooth aerodynamic contours. This fiberglas construction was compatible with treatment for low radar relection.

In several respects, however, the airplane was unsuited to desert utility applications. The landing gear would not operate from loose sand. The propeller thrust was not sufficient for sand operation. Also, a lower stall speed was required, and the wing high-lift system was not suitable for desert use.

It was proposed to modify the landing gear after design data was acquired. To increase the thrust, a later model of the Allison turbine was installed to increase the power from 250 H.P. to 420 H.P. A new three bladed propeller was required, and a new gearbox with a prop governor was installed. A larger oil cooler and cabin air conditioner with electric blowers for each were needed to operate in high ambient temperatures. Stall speed was reduced by increasing the wing area from 102.1 to 161.56 square feet, and increasing the span from 26.2 to 36.87 feet.

The Marvel II was flown August 17, 1982, a year after the project was begun on January 15, 1982. Approximately 50 hours of flight testing was conducted. An airplane maximum lift coefficient of 3.0 was measured. The takeoff performance was spectacular, but reduced elevator effectiveness at low engine power degraded the STOL landing performance. No structural problems were encountered during the flight program.