FDM Telescoping Wing UAV


Finally getting around to posting a project I worked on a year ago at MIT Lincoln Laboratory. We 3D printed (FDM on a Fortus 400mc) a UAV with telescoping wings. Structure was primarily FDM except for a carbon fiber backbone that all the parts were attached to. Designed to be highly modular, the aircraft was essentially 3 reconfigurable pieces: the fuselage pod on the front with the avionics and batteries, the wings, and the empennage. To adjust the CG for different payloads you could move all the parts around until you balanced and had the stability margin you needed. 

We printed the wings without support material and with an internal structure that made them pretty strong. We also decided to incorporate carbon fiber spars into the wings which essentially doubled our strength to weight and it took less than a minute to install. Combining COTS materials with FDM really helped alleviate some of the strength concerns we had.

I've attached a talk that my coworker and I did at the RAPID additive manufacturing conference this year which has some of our lessons learned and more information about our aircraft. Hope there is something helpful in there for anyone interested in doing FDM UAV design! RAPID Presentation

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  • Thanks, Eli!  Do you think that this mechanism could be used to build a telescoping wing with a ratio greater than 2:1?  I am attempting to maximise the difference in wing area between extended and retracted configurations, and am hoping for 3:1 or even 4:1...

  • Hey Jean

    The wings are driven in and out via a lead screw. In the above picture, the white outboard portions of the wing have a nut bonded onto the inboard edge and housed in the center is a gearbox driving two threaded rods. the rod is free to rotate while the wing is constrained in rotation so when you turn the rod, it drives the wing in or out. There is a microcontroller attached to the gearbox that keeps track of the extension so you don't disassemble your plane in flight. 

    there are a lot of different possible configurations for this aircraft. the lowest speed one is wings all the way out, flaps down 45 degrees. this gives you your lightest wing loading, but is also pretty draggy. likewise at full speed, when flaps are up and wings are retracted, you are running flat out, so endurance suffers. away from those two end points, the endurance jumps significantly. we wanted to make sure we hit the corner cases but we didn't plan on getting our best endurance there. best endurance is roughly when the wings are out but the flaps are not deflected.

    the outboard wing sections have significantly higher CL airfoils than the inner section so even though there is less chord (area), they have a pronounced effect at low speed. the center sections is a lower drag airfoil to hit that top speed. 

    the wing sees way more deflection with the wings out and care has to be taken not to pull any hard maneuvers.

  • Could you please explain how the telescoping mechanism works, and what effect it had on overall efficiency, strength & wing loading etc.?

  • Nice post Eli-- that plane is awesome. 

  • Hey Brian, we ended up making a lot of changes to the wings, mostly for ease of assembly. Flaps were enlarged quite a bit eventually as they were still pretty anemic being mounted so far inboard. Didn't do too much with the project after you saw it, maybe it will get picked up again sometime.

  • Eli, it's great to see you putting this out there. It was great to see it fly last year, any changes to the flap system or wing fences?
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