Double Eagle (oz5819)

About this Plan

Double Eagle. High performance aerobatic pattern aircraft for .61 cu ins engines with pump. Span 62in, area 675 sq in, weight 9-1/2 lb. Uses a foam core wing.

Quote: "What is it? Its a truly exciting new pattern ship that not only looks different, but has such ultra high performance that it may interest the USAF.

The built-in accuracy concept contributed much to the why-is-it of the airframe and structural design and dominated the construction and assembly procedures - to produce a winning pattern aircraft.

A discussion is in order concerning the design philosophy of the Double Eagle and what is behind its ability to accomplish some of its almost startling flight performance. I won't clutter up the discussion with any formulas or mathematical justifications which, at this point, are relatively meaningless but I will attempt to explain why the various aspects of the design do what they do.

Powerplant: The Double Eagle was sized to be an all-out performer with a hot .61 engine and to be almost unchallengeable with the addition of a piped Schneurle engine. The design was developed around a Veco .61 with Perry Pump and Carb., customized with PDP ala Clarence Lee. The development proved so promising that the prototype of the final design was completed and tested using that powerplant.

With its sleek lines, low-drag aerodynamics, and 9-1/2 lb flying weight, its speed and vertical performance are truly spectacular. With the design now proven, two of the identical aircraft with only slight modifications to accommodate piped engines are now in the works, and will soon be off the boards and flying.

Low Drag Design: Of all the factors that produce aerodynamic drag on an aircraft, the greatest, and most difficult to reduce is the drag that is induced by the production of lift. Of lesser severity, but still with great affect, are the frontal area (flat plate) drag, the profile or skin friction drag, and the various parasite drag producers such as: open wheel wells, exposed wing-bolt heads, etc.

The Double Eagle was specifically designed to reduce the major drag producers to a minimum. The basic wing section was chosen for its excellent high-speed/low induced drag characteristics. Also, its relatively thin airfoil section provides a mininum of frontal area drag. The mounting of the wing with its upper surface coincident with the top surface of the: fuselage. provides a smooth airflow transition and eliminates the traditional wing to fuselage buffet area which usuall can be only partially helped with transitional fillets. The wash-out in the wing, though primarily designed to enhance low-speed stability, provides a considerable contribition to a reduction in the induced drag during high-speed flight..."

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