A unique feature of the Power-Wing^TM concept is the ability to control the flight path angle. The WSU analysis showed that the approach and climb angle can be varied at constant airspeed by regulating the power of the blowing engine(s). This feature was demonstrated in flight tests of the Distributor Wing Airplane, where approach and climb angles were controlled by throttle setting of the blowing engine.

The following graph is taken from the WSU analysis. It shows how the rate of climb is affected by the power setting of the blowing engine. This shows that at reduced power settings of the main engine, the approach angle to landing can be regulated by throttle control of the blowing engine.

By regulating the power of blowing engines, a pilot controls approach angle and thus guarantees touchdown point. This also shows that the rate of descent is reduced immediately before touchdown. In effect, the blowing engine throttle is used to produce flare before touchdown. After ground contact is made, the blowing engine throttle is closed and wing lift is radically reduced. This eliminates the need for spoilers or drag flaps and allows for higher braking deceleration.

A comparison with an approach at an angle of 2.5° at an airspeed of 150 ft/sec illustrates the usual landing procedure. At this angle, the airplane travels 23 feet for each one foot of altitude change. The distance over a 50 ft. obstacle is therefore 1145 feet. Each additional foot of altitude at the 50 foot obstacle point increases the travel distance by 23 feet. A tolerance of +20 feet above a 50 ft. obstacle means that the touchdown point, assuming no flare, will be extended by 458 feet. The landing field length therefore must accommodate the ability of the pilot to control altitude in the approach.

By increasing the accuracy of touchdown, the effective field length is reduced. Flight Path Angle control is therefore instrumental in setting the required field length. The Direct Lift Control feature of Power-Wing^TM airplanes is a necessary capability to secure short field performance.