This is the scene that presented itself this morning:
Yesterday’s weather wasn’t bad, but it’s the wind that really did it for flying this morning. You can’t see from the photo, but those clouds are moving right to left at quite a rate. On the basis of what I’ve see so far, I would have got wet at around 10:30 and 11:30, with 11:30 more of a highly localised downpour. Now the Sun’s just come back out and we’re back to hot and humid again. It’s what you expect from a Bank holiday really, so I’ve resigned myself to this being a long building weekend.
I still haven’t finished covering the autogyro because of the extreme heat last week. I have decided on doing the tail in red, so I might get around to that later today. I’ve also been working on the quadcopter simulator. It’s really interesting looking at how Cleanflight works and I’ve tried to replicate it as closely as I can in the simulator. It now works on angular rate targets rather than absolute angles, so it flies a lot more accurately than before with more of that “locked-in” feeling rather than drifting all over the sky. I didn’t know this before, but Cleanflight actually reduces the PID rates in response to throttle changes. That’s not something I’ve implemented yet, but I’m going to experiment with it later. Now I’ve started getting into autopilot software and automatic control, I’ve been thinking about new things that I can do with this skill. I’m still interested in looking at some of the really old designs of aircraft (circa 1900) that failed and add modern computerised control software.
OK, now I’m going to use the time today to do some long awaited maintenance on the RS352. I’ve needed to change the battery in my Futaba FF8 for a while as it’s not holding its charge very well. Once that’s done I’m going to go through the programming with the RS352 and check all the control surfaces.
I’m a bit late this week as I’ve spent the day covering my ATOM Autogyro. There’s no flying this week as yesterday it was blowing a gale and this morning isn’t much better. It’s taken me a long time to get to the covering stage as it’s just been so hot recently that I couldn’t bring myself to plug the covering iron in.
As you can see, it’s taken me a long time to get this far and I’m not quite there yet. Normally you cover the bottom of the aircraft and it’s a nice and easy way to start, doing something that isn’t terribly visible and is square and flat. Not with this fuselage. I hadn’t realised how many compound curves there are to go around on the bottom. The sides were a piece of cake by comparison. It seems you never lose the knack for solar filming though, even after you realise that the blue metal flake film is partially transparent and is going to magnify every tiny little mistake. If you look at the tail closely, I’m disappointed at how visible the joins are. I was covering it using up my very last scraps of old (20+ years old) film and ran out on the top horizontal stabiliser surface. You can see the overlap where I’ve had to join three pieces together in a funny position. Oh, well, I’ll just have to get creative with the trim graphics. I still haven’t decided what colour to do the fin end plates or the blades, but that can wait for a bit. What worried me a little when I was covering the fuselage is just how top heavy it is. I’ve never covered anything like this before and it was so difficult to hang on to the thing as I was smoothing out the film as it kept trying to twist out of my hands. There’s just nothing to hang on to or rest flat on the work surface.
OK, so that’s the autogyro, but I’ve actually spent most evenings this week working on the quadcopter simulator. I’ve had a play around with a control system that could be used for automatic navigation. In the simulator I could just tell it to head in a particular direction at a certain speed and height and the controller would just get on with it. I was thinking that I could try out some of the synchronised manoeuvres that I’ve seen the GRASP Lab at Penn University put up on the Internet. I’m thinking of simulating it first as I’m currently lacking a vision system, but it would be interesting to explore what’s possible with some of the cheap hardware that’s around. In addition to this, I’ve been improving how the quadcopter flies in the simulator. It’s well worth having a look at the MultiWii rewrite controller in the Cleanflight code to see how it’s done on a real aircraft, but there are some subtle differences between that and how it’s done in a flight simulator. It’s all very interesting once you get into it and it’s making me think about whether I could construct something novel out of all this automatic control theory.
I flew a UMX Spacewalker this week and also had four flights with the RS352 (above). We also had a Multiplex Twinstar and a fantastic looking foam FW190. The Twinstar ended up crashing, but no real damage looked to have been done apart from where the nose had absorbed the impact and the right engine had torn loose. I had just launched it for the pilot, and it climbed out with plenty of power, but then it started to make a buzzing noise like the prop was catching on something. We couldn’t make out what was causing it while he flew a few gentle circuits. It was a vibration of some sort, but, not being the one on the sticks, I can’t say whether it was power related or aerodynamic. The next thing which happened was that it went into a right hand spin, so I suspect the right engine pod was the root of the problem. Anyway, it wasn’t badly damaged when it came down, so it will fly again. This was the same aircraft that flew without its wing spar installed a couple of weeks ago, and had the wings fold on launch. It’s having quite a troubled life at the moment, so, hopefully, it’s got all the teething problems out of the way at the beginning and will now fly on for years to come.
I spent two of my flights trying to avoid the FW190, which had some turn of speed and was bigger than me. He had retracts on it which we saw partially deploy a couple of times, but he didn’t actually use them for landing, electing instead to belly land on the long grass. That was probably a good idea, but we love to see the wheels pop down for landing. It’s just a shame that the Hurricane won’t be joining it in the air. I’ve known the owner of this plane for years, since I first saw him flying a bright yellow glider. We had another person from way back visit this morning, so we had an interesting talk with him and he had a go flying the UMX Spacewalker.
OK, I’m off to cover an autogyro now. I’ve decided, it’s going to be blue.
The weather is rather interesting today. It’s very hot, but it’s also very windy with the clouds skimming across the sky at some speed. The sunshade also blew into next door, so the decision not to bother going flying looks like the right one.
I spent yesterday trying to build another scene for the quadcopter simulator. With the Rio Olympics just starting, I wondered whether I could build a London Olympic Park model from bits of free artwork collected on the Internet. Having spent a day on this, I think I’m going to give up at this point as my artistic skills are not up to it. The picture above shows a fairly passable Arcelor Mittal Orbit, Aquatic Centre, main stadium and velodrome, but the textures are seriously messed up. The problem is the export path from Sketchup via 3DS and then into Blender before loading the model into the Unity scene. There are too many conversions between formats introducing errors where an importer can’t handle the format of the data in the previous step of the chain. Basically, it was taking ages and a lot of trial and error, leaving me with Blender models where textures, normals and vertices were broken. I think I have to accept that my artistic skills aren’t up to the job and go back to being a programmer.
Having spent quite a long time flying the quadcopter around the Olympic Park, I realise that I have some serious work to do on the flight simulation itself. The way it flies just doesn’t feel at all right, so I’m going to go back to the code and add in the motor force and moments modelling that I didn’t have time to do before. Then all the pieces should be there to tune it just like a real quadcopter.
Anyway, my plan for the rest of the day is to wait until the temperature is below 30 degrees and then think about covering the autogyro. I really can’t face the thought of solar filming in this heat, so I need it to cool down a bit first.