BENJ Aerospace
BENJ Aerospace is a project team consisting of previous colleagues and friends, Blake Andersen, Etienne Rimmele, myself, and Jonathan van Hyning. This quarter, we were tasked with designing a plane optimized for carrying the heaviest payload. The payload being carried is golf balls, and the plane is a remote-controlled built-up craft. We had the privilege of utilizing provided resources from the Jacobs School of Engineering, consisting of a lab workspace and storage, a plethora of materials, various fabrication machines and tools, and guidance from professors, experts, and lab techs. 10 weeks were given for design and build, with a final presentation, engineering fair, and fly-off date to complete the quarter.
A picture with the completed plane and the team on fly-off day.
Final Fly-off and Reports
Click on the image below to watch our successful flight. To the right are the various reports and presentations completed throughout the quarter. Thank you to the Mission Bay Silent Flyers Field Club for providing us our flight location and pilots!
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Wing Structure
A wooden built-up format is used for the wing. Ribs are laser-cut basswood. Spars are carbon fiber, cut with a dremmel. Leading and trailing edges are supported with bent balsa wood using a heat gun. Everything is adhered with epoxy and CA glue.
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Fuselage
The fuselage is an easily manufactured laser cut basswood. A tail-dragger configuration is used for landing gears.
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Aerodynamics
A Gottingen-498 airfoil is used. Due to low Reynold’s numbers and slow flight, an airfoil with a round leading edge and large camber is chosen to maximize lift.
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Avionics and Control
Avionics consists of a battery, power supply, RF receiver, servo arms, motor, and various wires. Avionics are mounted to the fuselage using velcro strips and tape.
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Aircraft Surfaces
Wing and fuselage surfaces are covered using a material called Monokote. It is a thin vinyl-like substance, similar to car wraps. It is applied using heat pads and heat guns, and becomes tight and smooth.
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Propulsion
The aircraft is propulsed by a single propeller mounted on the nose. The propeller chosen is an APC 9x6E. The motor produces up to 10,000 RPM.
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Empennage
The tail is made with a foam-cut NACA 0010, and has a wide rudder and elevator control.
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Wing Mount
The wing attaches to the fuselage directly above the payload’s entrance using velcro strips and rubber bands. This style of mounting allows for the wing to freely mount forwards and backwards to adjust stability.
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Stability
Tape marks our center of gravity with and without payload to maintain a static margin of 15%. This percentage allows for pilots to adjust trajectory easily, while staying in a controlled, stable path.
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Payload
The payload is loaded through a top hole in the fuselage, and is grouped using foam pieces and rubber bands to minimize shifting.
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CAD
A fleshed-out CAD of the plane is made to easily choose components for manufacturing. The CAD allows for a theoretical center of gravity and stress analysis to improve design parameters, as well.
Fabrication and Testing Processes
Here are a collection of short videos demonstrating a few fabrication processes used for the manufacturing of the plane, as well as some testing.
Laser Cutting is used for all wooden portions of the plane.
Balsa wood a a very light, low-density wood. We were able to bend it around our wing using ample heat.
Ailerons are tested for responsiveness and trim.
A dremmel is used in conjunction with a downdraft table to cut any carbon fiber.
Heat pads are used to adhere Monokote to the wing and fuselage. A heat gun used later shrinks the wrap, which eliminates any slack or wrinkles after application.
A ground roll is done to verify a straight and stable path for the plane.