Project Title

Composite Ruddervator Replacement

Document Type

Undergraduate Project

Date of Degree Completion

Spring 2020

Degree Name

Bachelor of Science

Department

Engineering Technology

Committee Chair

Dr. Craig Johnson

Second Committee Member

Professor Charles Pringle

Third Committee Member

Dr. John Choi

Abstract

The Beechcraft V-tail Bonanza is a popular general aviation aircraft. Over 10,000 were built, but with the weakness of magnesium skinned control surfaces. Control surfaces on aircraft must be light, and precisely balanced. The V-tail Bonanza uses a unique “ruddervator” system, which combines the rudder and elevator into one surface to reduce drag, controlling the pitch and yaw of the aircraft. Magnesium was chosen by the designers for its lightweight properties, but corrodes badly and is becoming difficult to source for replacement parts. Aerodynamic flutter, from flexibility in the lightly built surface, and corrosion can cause breakup in flight, and has grounded many aircraft. A complete replacement is needed, but cannot be constructed of aluminum due to its weight. In this project, a cored carbon fiber composite material was used to construct a prototype. The dimensions and mounting hardware are unchanged from the original surface, allowing a direct swap onto the aircraft, with no changes to controls, trim, or cable routing. Carbon fiber will not corrode, and is an extremely stiff material. Two layers of biaxial carbon fiber cloth are separated by a solid foam core, with bolted hinge attach points. The prototype was tested by static loading using sandbags in a welded steel jig, simulating an aerodynamic load, while measuring the distance of deflection, and eventual failure point, to identify weak points and stress concentrations. The new surface was shown to have a 20% improvement in stiffness and strength over the original, as well as reducing aerodynamic drag.

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