The roads are closed this weekend due to a cycling event, so no (fixed wing) flying this week, which is a shame because the weather looks so good.
I have spent most of the week playing with my DaVinci Aerial Screw though. I’m now on the second prototype which uses a 1/32 ply ring and three spruce spars to hold the aerial screw, which looks a lot more like the DaVinci drawing.
The aerial screw itself is still a bit of a problem. In the original drawing, it’s obviously bigger than the circular base of the pyramid frame and flatter. The smaller diameter screw affects the performance of the quadcopter rotors a lot less. I’ve been testing different sizes and shapes all week and now have a fairly good idea about the trade-off between height, diameter, screw type and spin speed. I also wanted to make the screw look more antique, which I think I’ve achieved fairly well here. This version is made from light pastel cream coloured cardboard, which is then treated to make the antique faded parchment effect. I wasn’t sure how to go about this initially. Various people had suggested coffee, which is baked in the oven to make the card take on the yellow aged effect, but at the expense of making it brittle. So, I settled myself down with a cup of tea to have a think about it and the idea suddenly hit me. I went back and got the used tea bag and dabbed it onto the cardboard aerial screw. It does make it go a bit soggy, so I had to put weights on it to press it flat while it dried out, but the effect is quite good. The black lines you can see are just marker pen.
I also had a look at creating the cords which hold the aerial screw in place and are a prominent feature of the DaVinci drawing. Unfortunately, I can’t think of any way of doing this with the current design. My original thought was to stiffen cotton thread with cyano and attach it to the screw with a dab of glue. Then the thread would run around the outside edge of the ply ring when the screw was turning. I can’t find any way of doing this without the threads getting caught and sucked into the quadcopter rotors. I’m just going to have to find a way of securing them on a rotating platform, but that’s for prototype number 3 which will replace the white 3D printed frame with something wooden.
As you can see from some of the flight tests, it’s actually quite controllable once you get the aerial screw right. And lots of fun…
This one’s interesting because the battery came loose and was dragging along the floor. From my viewpoint above the camera, I can’t see this. All I know is that suddenly it’s all over the place.
I think that’s enough playing around with quadcopters for a bit. I’ve got to go and finish off an autogyro.