The Martlet

drafts

 

In 2015, AERO McGill designed and fabricated The Marlet, a fixed-wing, remote-controlled aircraft, that participated in the Micro Class of the 2015 SAE Aero Design East competition in Lakeland, Florida from March 13-15th, 2015.

Assuming the aircraft was airworthy and stable, the competition was to be won by the aircraft with the highest payload factor – that is, the aircraft carrying the highest payload with regards to empty weight. With this information in hand, the team set out to design an aircraft capable of high lift at low speeds, which required a suitable airfoil. Thus, we chose the Eppler E423 and optimized the wing shape and structure to be sufficient to achieve a payload factor around 0.6-0.7 given an aircraft gross weight of 2.2lbs (1kg).

Wing Characteristics

Span 39.37in (1m)
Chord 5in (0.127m)
Area 206.15in2 (0.127m2)
Aspect Ratio 7.52
Wing Efficiency 0.82

 

Using these dimensions, the team set out to determine the theoretical payload yield at different altitudes and produced the following results:
Payload

 

The next step was to determine the aerodynamic and static stability of such a wing set-up, and so a stability analysis was performed using XFLR to determine the aerodynamic center and the center of gravity of the aircraft.
XFLR5 Finally, the team set out to design the remaining components, including the 1.5inx1.5inx5in payload bay to fit inside the fuselage.oldrenders 900px

The wing, and the entire aircraft, were constructed of laser-cut balsa and plywood, and 3Dprinted components. The wings were wrapped using a vinyl, heat-shrinking material. Below is a view of the final render of the competition aircraft:

Final render 900px

A look inside the wings of the aircraft, and an overview of the competition aircraft at the final inspection table at competition:

 
openwing 900pxat inspection 900px