Geodetic Glider

thingiverse

A half-metre wing-span model of a Waco assault glider, as used by US forces in WWII. I'd set my students the challenge of designing a glider, in groups, which could be 3d printed and then launched fro a bungee catapult - it was a design and project management exercise rather than a flight challenge, but we encountered a problem which proved quite difficult to overcome. Printing in PLA, the gliders all came out very heavy, which lead to a very high wing-loading and, as a result, very poor flight performance. Although I tried to improve matters by allowing ever larger wing-spans to try to reduce wing-loading, the majority of the designs the students were coming up with were essentially solid structures, so the wing-loading stayed more or less the same - there proved to be practical limits to how big a wing-span you could go for and achieve a rigid structure without resorting to glue, too... This is an experiment in creating a frame-structured glider, which can then be covered with heat-shrink film (solafilm or similar). I took inspiration from the designs of Barnes-Wallis to create a geodetic fuselage which could be printed in sections without the need for supports; all of the .stl files will print this way, although some of them not as cleanly as I'd have liked... My plan was to join all the sections together with small printed pins - the student project required the gliders to be assembled without glue. Unfortunately, the pins didn't print very well (they were too small for the resolution of my printer and tended to break apart when I took them of the build-plate), so I used short lengths of cocktail sticks and...well...glue instead. I've designed the glider to take micro-servo's in the wings and fuselage to control the flight-surfaces, but never got as far as fitting them before this project fell by the wayside - you can see from the photo's that the ailerons, rudder and elevator are all awaiting fitting - I was just going to use tape as a flexible hinge. Because this is a bit of a "work in progress", I've included the .dwg for anybody who fancies modifying or improving the design - have fun etc. :)