A 90% successful mill. Both sides lined up perfectly. Will just have to make the tabs a little more sturdy next time and change the angles of the wing tips in the material. The trailing edge of the foil is obviously too thin as can be seen in the video, but that was more because of the initial 3D model I made. I’ll probably stick a 2mm thick square trailing edge on it so that it’s a clean cut.
We’ll laminate this one and give it a test fly anyway. Hopefully I can edit the 3D and make the next one in the next few days.
We managed to mill both sides OK, but misregistered the second cut. It still flew somewhat. The video shows the wings starting to yaw sideways, but there’s no vertical stabilizers, so it’s to be expected.
Roger took the tape off the plane yesterday. The tape had really been doing a good job holding the whole thing together. 170g of tape all up. I thought I might get a minute or 2 of flying out of it, but as the video shows it did a lot better than that.
From here we’ll probably Araldite epoxy it and use the paper laminate system. then we should have a pretty solid wing.
Finally found some time to put some control gear into #Gemot. Gemot lay in the back of my van snapped in two for several weeks and I’d kind of forgotten about her. Then I thought to myself that I just want to prove that she may fly enough with RC control gear in her. I’d probably crash her in the first two minutes, but that would be long enough to prove the theory.
Well it flew a lot longer than that and was far more stable in the sky than I expected. I didn’t even glue the crack together. Duct tape seemed to do the job well enough. Gotta love that ‘Bear’ brand duct tape from Bunnings!
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.