3 Characteristics of Aircraft Wings: T-1A Jayhawk — Airplanes by Design

The T-1A Jayhawk is a variant of the BeechJet 400, used by the US Air Force for training tanker and transport pilots. This aircraft serves as an introduction to 3 design characteristics of aircraft wings: aspect ratio, airfoil, and aerodynamics.

Aspect Ratio

This photograph was taken from a second T-1A in a formation trail position that simulates the precontact position of aerial refueling. From this photo, we can estimate the aspect ratio, which is proportional to the wingspan over the wing chord. Since the chord of the T-1 varies, the actual definition of aspect ratio is AR = b² / S.  Aspect ratio affects performance, flying qualities, structural, and practical aspects of aircraft design. Normally we think of fighter jets as very low aspect ratio, highly maneuverable and fast aircraft. Conversely, high aspect ratio aircraft like gliders are usually slower and designed for high lift soaring flight.

Airfoil

Though difficult to see clearly here, the T-1 has a supercritical airfoil–like the C-17 and NASA F-8–designed to increase critical Mach number (delay drag increase caused by supersonic flow of air over the wing).

The T-1 has an extremely long flap, as seen here, that extends almost two-thirds of the wing span.  Extension of the flap alters the airfoil shape and the aspect ratio, usually by increasing chord length (and thus wing area).

Aerodynamics

This photo reveals several interesting aerodynamic characteristics. First we can see both a stall strip and stall gate on the wing near the root. Swept wings normally stall near the tips first. When it does, the aircraft tends to pitch up, a response that is undesirable to pilots, so the stall strip will change the stall behavior to mimic straight wing characteristics. Additionally, the design of the leading edge (to incorporate anti-icing) poses a challenge for maintaining laminar flow.

The T-1 uses the spoiler as the primary roll control. Trim control uses the aileron.  This reduces asymmetric yaw (a normal response to aileron input).

In 2012, the Airplanes by Design column will feature How to Take an Airplane Photo posts on the ABC’s of aircraft design characteristics according to the following schedule:

January: ABC’s of Aircraft Wing Design Characteristics (Letter “a”, etc.)
February: ABC’s of Aircraft Engine Design Characteristics
March: ABC’s of Aircraft Fuselage Design Characteristics
April: ABC’s of Aircraft Tail Design Characteristics

This schedule will be similar during the subsequent trimesters of the year, but it progresses through the alphabet.

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