Happy Birthday Mustang!

I’ve been flying the Mustang for over a year now. I’m not sure of the exact date, but it was new in mid September of last year and it’s still going strong. I’m genuinely surprised at how the motor and gearbox are still going when it gets about two hours of flying time a week.

The weather was almost perfect this morning, although a little less breeze would have been better. When I arrived there was only a young boy there, with two Mustangs of his own. He was throwing his around the sky like a crazy thing, so I joined him. Now, I had guessed by the plethora of Mustang and other boxes, plus him being about 10 years old, that he wasn’t here on his own. Not too long after, his dad and his brother turned up having just been looking for a lost aircraft at the edge of the field. Yet another one seems to have gone missing as they were unable to locate Mustang 3. And apparently, this was not the first one they had lost. That’s the problem with these aircraft that can fly themselves. People who aren’t used to the “never take your eyes off the aircraft” training look away and lose it, at which point it keeps flying on the gyro and ends up crashing a long way away.

They didn’t stay long after that, but we had quite a good chat about Mustang flying. They tried to show me its “return to home” function, but that’s not what it is. It took me a while to figure out what they were talking about, as it’s got no GPS like a drone and can’t return to home like they do. Then I remembered that the manual details a “return function” that I think is more like an aerobatic function than a return to home button. The way they describe it is that you throw the aircraft away from you to launch it, then press the return button and it flips itself around and flies back to you. That’s not a panic button return to home like they were thinking. Anyway, fly it close to you and always keep your eyes on it and don’t get distracted. Funnily enough, that’s how I ended the morning when somebody did exactly the same thing with a Mavic Mini and we were scouring the sky for where it had gone.

After they left, another guy turned up with his Mavic Mini (instead of his Inspire), then another guy with the Multiplex Cub and Heron from last time. I managed my usual 7 flights with the Mustang, although some of my LiPos seem a bit tired and lacking in power, if not duration. I was managing between 10 and fifteen minute flights, which is a lot of flight time if you’re trying to fly on the expert mode for most of it. The Mustang definitely needs a lot less aileron movement on expert mode. It’s programmed to up the control rates from basic to intermediate to expert, but it’s far too much. I was trying to do stall turns, flick rolls and spins and realising that it’s almost impossible to fly this aircraft accurately. The stall turns are impossible because it won’t hold a straight line on the up, then doesn’t have the mass and momentum to do the flick around on the rudder at the top. The flick rolls just don’t seem to work very well. You can just about get a wing to drop with a sudden rudder input, but that’s all it does. The wing drops and it doesn’t have the momentum to spin all the way around. I had some fun putting into into all sorts of odd manoeuvres, though.

During the rest of the morning we also had some kids with a DJI FPV, another drone that I couldn’t see properly at distance and then two guys each with Mavics. Actually, the first one asked me what height I was flying at when he had his first flight as I was flying my Mustang. He didn’t seem to realise that I had no way of telling height apart from my own judgement. I should have told him that my aircraft was £50, while his was almost a thousand. Never mind, though, as he was only trying to see what height I was flying at so that he could set his height to stay above me. It was when his friend turned up and was flying his Mavic that he lost sight of it. He took his eyes off of the quadcopter and it wasn’t there when he looked back. We could see which tree it was pointing at on the display, but even I couldn’t pick the thing out of the blue sky. So he pressed his return to home button and it found its way back until it was over our heads. I saw it first and pointed it out to the other two. It was really high up, so no wonder we couldn’t see it at distance. Then the computer landed itself and all was well.

That was my flying this morning, in what was increasingly becoming a very Autumnal morning as things progressed. We might even have a new arrival next week. The guy with the Multiplex planes is building a FliteTest foam board Spitfire. He’s getting on with it much faster than I am with my Dimension and it’s apparently nearly finished. I do have some progress to show, as I did finally manage to fly my Dimension this evening, but only on the computer. The graphic model is finished to the point where it’s good enough to pass for a plane. The only thing is that I may just have built the world’s ugliest looking plane.

I was going to do it in green solarflim as I’ve got a lot of WW1 green that’s left over from a Sopwith Pup I made many years ago (OK, I miscalculated and bought much too much). I think it’s a bit darker than the green in the picture, though, so I should give the computer model some tweaking before deciding that it’s horrible. It should really be blue to match the wheels, but I do love the shape of that wing.

There is my RS352 model on the right, fully textured, along with the Dimension on the left still in its bare bones (look at the shadows). There are a few things wrong with the model, for instance, the green fuselage is so dark as to almost be black, there are a few holes in the model and the wheels appear to be white when they should be black. Actually, compare the last two pictures and see if you and spot the differences yourself.

Well, I said I was flying it in the simulator, with a first approximation of the flight characteristic data too. It’s got the same power as the RS352, about half the wing area and it’s about 100g heavier and it was flying beautifully. It now gives me the confidence to think that the real one could actually fly, if only I could manage to finished it.

There it is in the simulator, flying with it’s underside on view and showing those beautiful wings which I just loved the instant I saw them. This has to fly now.

Bright and Breezy in the Metaverse

No flying this weekend, but it was a bright and breezy morning. I might have gone if I could, but it was really rather windy. The contrails in the picture above looked quite striking when I stuck my head out of the window to see what the weather was like. It’s really feeling like autumn now as the nights are drawing in and, although sunny, the heat of last month has gone completely.

I had a fly of the simulator instead and ended up trying to flick roll a virtual Extra 330 and fly a Weasel foamie slope soarer through a limbo on the edge of a cliff. Lots of fun, but not quite like the real thing. My intention was to finish off the simulator model of my own design “Dimension” aerobat, digitise all the measurements and put it into my own simulator to see how it might fly. It didn’t quite work like that as I realised that I’m not very quick with 3D modelling and it would take me all day. Then I got distracted with the real one as I haven’t done any work on it for over a week. So, instead of modelling a virtual one, I ended up filing out lightning holes in the real one to tidy it up and get it ready for covering. I think I can save about 70g in weight, but it’s still heavier than my EPP foam RS352, which looks a lot bigger and has half the wing loading. I still can’t get my head round where the weight is being added, but I suspect that the wood construction is just plain heavier than EPP. I also think that the oversize EPP fuselage helps with reducing weight, as there’s less need to reinforce with thick bits of foam compared to 6mm balsa. When you look at the RS352, its fuselage is 15mm thick, which is something I hadn’t appreciated before. However, the Dimension is built on a 6mm spruce spar, so it was only ever going to be 6mm wide. I now have a spreadsheet with the weights of all the pieces on it, so I’m just working my way through and seeing where I can lose some weight. It’s a painful process though and the rudder is next for the hole cutting. I’m hoping for 10g there.

So there we have it, the Dimension still needs a fair bit of work to make it flyable and I may have another go at simulating it either tonight or tomorrow. It’s always good to simulate things and also on my to do list is learning how to use XFoil. I could do with generating some polars for those strange foam board wings that the Dimension has and which were copied from FliteTest’s technique. This is something that I’ve been thinking about for a while, but not progressed at all. I really need to get back into writing my own simulator, but writing a drone book is taking precedence at the moment. That’s another task for tonight. Try out the motors on my micro:bit drone to see if they work with the new connectors I soldered yesterday and then get it up on the test rig to see if the auto-levelling works.

With all that to do it’s a wonder I get any real flying in at all, but I should be back in the air next week, weather permitting.

The Last Hot Days of Summer

I was a bit over dressed this morning. I hadn’t realised how warm it was going to be. When I left the house it was dull and overcast, but, at the flying field, it was hot and sunny. The weather stayed good for most of the morning, with it getting a bit windy towards the end and the clouds arriving to make the cycle back a little more pleasant.

It was busy too, as I was joined by my friend with the Heron and Xeno as you can just see from the image above. The Heron goes really well in these conditions. There were thermals all over, but nothing I could exploit with my little Mustang. I would really like my own glider, but big wings and fuselage are impossible to get on the bike. This Heron is 2.5 metres, but it was out-flying my Mustang, which is no mean feat when I’m getting 10 to 15 minute flights. I was getting about 2 of my flights to one of the Heron, and even then, the Heron still had some power. The Xeno flying wing is something to see too. The power it has is incredible. For something that is a similar size to my own flying wing, it’s just in a league of its own.

I had my usual seven flights with the Mustang, with rather a lot of it on expert mode. I tried practising some flick rolls, but aerobatics are not at all easy. On one occasion I managed to drop the speed right down, pull up slightly and hit full left rudder, at which point the left wing dropped sharply and it came right around 360 degrees until I released the rudder. It didn’t look much like a flick roll, though. Certainly not like the ones I was doing with my RS352. It was more of a spin, but not really a spin either. I also had a go at some stall turns, but that was a bit of a disappointment. I can’t get a nice vertical climb and I can’t get a good flick around at the top. The weirdest thing I managed to do, though, was an out of control multiple spin. This has happened a few times now and it occurs if you pull up into a loop, but don’t have enough speed to get over the top and you get stuck on the apex. At that point the aircraft just spins completely out of control in a manner that no aircraft has a right to do under the laws of aerodynamics. This is in expert mode with the gyro off, so there should be no computer control coming into this. If the gyro is really off, then it’s either a weird radio glitch, or I’m getting outside the normal flight envelope. I can’t do it deliberately yet, but some more investigation is needed.

Other than that, it was perfect weather, there were at least three other people who turned up with drones and then my friend who flies the gliders turned up with his son just as I was getting ready to go home. I stayed a bit longer and watched them test fly an electric glider and a Gentle Lady pure glider. The electric one needed a bigger prop, and on the second flight it was completely transformed. It looked quite lively, though.

I really need a new plane, so the Dimension that I’m building has to either fly or not fly. Just to rub salt in the wounds, the guy with the Heron has just built a foam board FliteTest Spitfire. I need to do something like that, but I’m having trouble finding and building aircraft that are transportable by bike.

The image above shows my 3D model of the Dimension, which I will be able to simulate fairly soon. Actually, I could just put the numbers into the simulator and use a different graphic, but it always helps to have something that looks vaguely like the real thing. I’ve been gradually shaving a gram here and a gram there off of the real one, so my projected wing loading is just over 40g/dm2. It should be flyable, but duration might not be very good. Anyway, I need to order some more carbon to replace some of the structural items and save some more weight. Then probably add it all back on with the covering.

Either way, I need an aircraft that I can really fly.

Disappointed, Aborted

I got about half way to the flying field only to find that there was a road race happening this weekend and all the roads were shut. I turned around and went home again, really disappointed, because I was looking forward to flying again after missing last week. It would have been a bit of a marginal one, though, because it was really windy. There was rain about too, getting carried on the big low pressure zone that we’re sitting right underneath. You could see the rain clouds in the sky, but they always seemed to be a little way off and the sun was poking through, making for a bright morning.

Anyway, I decided to make myself a simulator model of the Dimension aerobat that I’ve been building.

I really need to get a document scanner, as you can see the rudder is a bit skewed by my camera’s lens. The fuselage has been built straight off the plans using measurements, but the rudder, being all curves, is easier to draw over the plans and then fiddle it to the right dimensions later. You can see that my plans are very old school, being pencil drawings on paper rather than CAD. I don’t get on with CAD, so I did it the way I’m most comfortable with.

It shouldn’t take too long to build something that I can fly in my simulator and then I’m back to where I was in the old days of making own design aircraft and flying and tweaking them on the simulator before flying them for real. I think I need to get this working on the computer before I get bored of making the real one and give it up completely. Progress has been slow this week as I’ve been cutting lightning holes wherever I can in an attempt to get the wing loading down. If I can show on the simulator what the flight characteristics could be, then I’ll be excited about flying it again and might actually get around to finishing it.

Talking about wing loading, my calculations show that it’s really a lost cause to think about lightning the structure to get from 40g/dm2 down into the 30g/dm2 range. The structure isn’t the greatest weight and it basically needs either super light radio gear, or more wing area. Going with the wing area idea, I had seriously thought about making it into a biplane. It’s been a possibility since the very early days when I was drawing the plan up, but I think it’s more sensible to try it out as a monoplane first and then make any modifications later on. Otherwise I’m just never going to finish this thing and fly it.

The oppressive heat seems to have drained out of the world now and we’re moving into Autumn and Winter. I need to get a test flight in while we still have good weather.