This was a short project to see how much effort was needed to make a fully functional delta-wing aircraft out of a single slab of XPS (extruded polystyrene).
Work begun with a single 600x1200x50mm slab of XPS which can be bought at your local hardware store. It is important to use XPS and not EPS which will desintigrate when cut.
A simple triangle template was used to give the overall shape of the aircraft. -Many designs are available online.
The XPS slab was first cut to 600x600mm using a regluar wood saw, and cut again down to a thickness of 25mm. The overall shape of the craft got marked out on the slab, and then cut with a fine wood saw. Unfortunately I don’t have any pictures of this stage.
The final, most time consuming and important step is to sand down the model unitil the wings have a nice airfoil shape to them to create the neccesary lift.
60 grit sandpaper was used all over the vehicle, and a template similar to the one above was utilized to ensure a nice airfoil shape.
Rudders made from thinner XPS were attached using fibre-reinfored tape and connected to ordinary 9g servos. As one can observe in the following image, 4 rudders were used in this design, enabling a form of air-brake when the rudders on the same wing are placed in opposite directions. A conventional design has one rudder on each wing, encorporating the elevator and aileron control in the balance between the two. (Elevon http://en.wikipedia.org/wiki/Elevon).
Finally a spread-spectrum 2.4GHz reciever, 25A ESC, 1000mA 3S 30C Li-Po battery and a 1800kV outrunner motor was attached.
Notice the front battery velcro attachment point which is long enough to allow some adjustment of the battery position. This is important to get the center of gravity correct, which should be at the center of lift somewhere around the middle of the wing. Finally, some static rudders were attached to give the aircraft more directional stability.
Before flight, remember to enable the “Elevon” setting on your RC controller.
A final tip is to adjust the sensitivity of all controls. I have used an exponential setup which lets movements around the central stick position have little effect, while more aggresive use of the controls results in larger servo movements. This deltawing turned out to handle very aggressively, so one might want to reduce the rudder surface area in new designs.
Overall the project has been a great success, and the model turned out to handle well after the mentioned control adjustments.