Here we’ve developed a prototype flying wing made from extruded polystyrene. The foam was easy to shape by hand, but it is very brittle as can been seen by the final impact on this video. Overall I am very happy with the outcome as the foil design worked perfectly. The wind was blowing up the hill varying in direction constantly at no more than 4 knots. The wing seemed to have adjusted to the different wind angles and speeds extremely well. In all prior flights it always self stabilized and landed the right way up.
200g of lead was used just in front of the centre of lift in this flight. The thickest point of the foil was ~ 20% from the leading edge with a thickness to chord ratio of about 13.8%. The central part of the foil does have a camber, but I didn’t exactly calculate it out apart from the fact that the leading edge was 1/3 up from the bottom of the foil.
The wing tips before the turned up winglets had symmetrical foils with the chord angled at about 17 degrees to that of the central main lift foil. This was to try to zero the lift at the wing tips to reduce tip vortex.
In conclusion the RC version would be extremely stable, but a better material is to be found for construction. The existing foil could be glued back together and skinned with a resin and glass construction, but that’s rather tedious. Also it won’t resist impacts on solid ground. We are currently looking for suppliers of EPO foam as it appears to work very well in other production models like the Ridge Rider available from HobbyKing.com
I’ve given this design the name #Gemot for easy reference. Strange name? Yes, so it doesn’t clash with too much on the net.