Slot Interceptor

Well within Frederick Handley Page's arm-reach last week was a $100,000 prize put up by the Guggenheim Fund for a plane which best promised safety in the hands of even an inexpert pilot.

The slotted wing is his device. When the ordinary airplane rises at too sharp an angle with the ground, air, which must stream sucking over the wings to support them, cannot reach enough wing surface to do its work. Consequently the plane loses flying speed. It stalls. Then it drops. The Handley Page wing contains a long narrow auxiliary wing set in its forward edge. When the main wing reaches the stalling angle, the auxiliary flaps up and suddenly presents a new surface to the wind. The wind also rushes through the space between the auxiliary and main wings. The result is that the plane is simultaneously supported at its sharp angle and thrust toward a level keel. The plane does not! drop under conditions where standard ones would.

One flying difficulty even slotted wings have not overcome: the falling of one wing and the consequent rising of the other. The plane tilts until it is liable to go into a spin.

To overcome the beginning of a spin the pilot must use his ailerons (small auxiliary wings fixed in the back edge of the wings). When one aileron rises, its opposite drops. That gives an opposed effect which ordinarily permits banking and turning from a straight level flying course. It also overcomes spins, if the pilot is alert and maneuvers quickly. But at the stalling angle the ailerons work sluggishly when at all.

So Frederick Handley Page invented his slot interceptor, last week announced as effectively tested. The interceptor is a second long narrow wing set just back of the slot at the main wing front. Like the auxiliary wing in front of it, it normally lies within the main wing surface. The interceptor is connected by bars to the aileron of its wing.

If in flying at the stalling angle with the automatic slots open one wing drops, the pilot raises the aileron on the opposite side. The aileron movement raises its interceptor to a vertical position. The interceptor interrupts the air flowing through the slot before it. Thus the wing gets no air lift on that side and it drops until it is level with the previously dropping wing on the other side of the fuselage. Thus does the pilot have a good opportunity to prevent a spin and to pull his plane out of its stall.

The Guggenheim Fund safe aircraft competition will be derided next October. A dozen airplane manufacturers are enlisted in it already. U. S. entrants are Curtiss Aeroplane & Motor Co. of Buffalo, Schroeder-Wentworth Associates of Glencoe, Ill., Charles Ward Hall Inc. of Buffalo, J. S. McDonnell Jr. & Associates of Milwaukee, Heraclio Alfaro of Cleveland, and Brunner-Winkle Aircraft Corp. of Brooklyn. If they do not win the $100,000 first prize, they may get one of five $10,000 "safety" prizes.