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A New Thing Spreads Its Wings

It’s blowing an absolute gale this week, so I’m still grounded. That’s probably a good thing, though, as it’s the drone masterclass next week and I’m snowed under with work.

Earlier in the week I got a new 3D printed quadcopter frame to fly. It’s a very strange and mysterious creature from the early Jurassic. Can you guess what it is?

OK, it’s the Dimorphodon model. When I was filming the first flight, it was a bit dark and I looked back at the flight video and saw that the shadow it cast on the wall looked just like the fossil picture I was copying it from. So, afterwards, I got a desk lamp and hung the model on a piece of wire so it cast a shadow. Following a tricky bit of juggling with the Dimorphodon on a wire, swinging around in front of the lamp while I tried to work the camera one handed, I got the photos above. If you look at the pictures, the wire it’s hanging from is obvious, but it does look like a fossil.

We decided to go back to the model with the wings spread out full span, rather than the folded wing model that I showed a couple of weeks ago. I’m really pleased with that decision as the results are fantastic. I’ve always wanted my own flying pterosaur ever since I saw the one in the movie “War Games”. Of course, a bigger, gliding, version would be better, but a micro quadcopter will have to do. These images show what it really looks like:

And, yes, the head is held on by foam tape, but it’s all I had and I was in a hurry to film it flying. I think the flying videos are going to have to wait until next week.

That’s it for now, I’ve got an aero turtle to make…

Still Grounded

It’s been drizzling with rain all morning, so, in retrospect, staying indoors was definitely the right choice. I’ve built an FPV micro quadcopter for the workshop we’re running in a couple of weeks.

OK, so the camera’s a bit wonky, but I’m waiting for the glue to set before I fix it properly. I’m quite pleased with this as the flying weight is 54.9g, whereas a regular HubSan X4C (HD) is 51.0g. This is the quadcopter frame from the “Acrylic Blue” video in January, which is the lightest I have. The FPV camera is a cheap one which only cost £30, but weighs over 9g, compared to the 4g weight on my £50 Hyperion camera. This way, I’m hoping to get flights of over 4 minutes out of it, but I haven’t done a proper duration test yet. All the electronics check out, using both the FatShark Goggles and my Black Pearl screen. To make the screen work, I’ve made myself a custom power lead which has the Black Pearl 12v jack plug on one end and a Deans connector on the other. That way I can use my regular flight LiPos to power it as the screen’s internal 3S battery is completely wrecked. The funny thing is that the goggles worked straight away, but I had to switch the screen from NTSC to PAL. I’ve had both of these working with my Hyperion camera on NTSC previously, so I can only think that I must have already switched the goggles and just forgotten about it? For anyone who doesn’t know, once you get the right band and channel, you should see some sort of image that you recognise. If it’s black and white with the image rolling slowly down the display, then the NTSC/PAL setting is wrong and the transmitter and receiver are using different modulation schemes. I haven’t found any compelling reason for choosing one over the other yet, so stuck with the PAL that the camera was set to. It’s usually configurable at both the transmitter and receiver end, but the cameras are tiny and usually harder to figure out. The video looks really good, so I’m looking forward to flying it around the house (with blade guards added).

That’s ticked off my main task for today, but now I’m off to fix the geometry on my Dimorphodon quadcopter frame so I can do a 3D printing test tomorrow.

Downtime

The weather has been appalling recently, with gale force wind and rain, so I’m stuck inside this weekend. I’ve been keeping busy by converting another of the HubSan X4Cs for a workshop we’re running in March. It took all day as I’ve been filming the process as I go along, so it should be interesting to see how the final video turns out. This time around we’ve also got a £20 FPV camera so we can give them a go with the FPV goggles.

DanaTheDimorphodon.png

Also for the workshop, I’ve been playing around with a new design of 3D printed frame. This time, it’s a Dimorphodon dinosaur skeleton. It’s a bit ambitious, and I’m not sure if it’s going to work, but it’s been fun sketching it out. I think I’m going to stick with the flat style of 5mm high extruded frame rather than go the whole hog and make it properly 3D. I’m not entirely sure where I’m going to put the four motors yet, though.

In addition to this, I’ve finally got two new LiPos for my RS352.

I opted for some Hyperion 1300mAh LiPos, similar to the original ones which worked really well. I ordered them from Robot Birds on Sunday and they had arrived by Tuesday. Fantastic, but those XT60 connectors will have to go as I use the Deans ones. I would have swapped them over today, but I’ve been filming the HubSan conversion process for most of the day. That can wait until next Saturday when, hopefully, we’ll have better weather. It sounds like the wind is trying to tear the roof off at the moment.

 

Waiting for Rain

It’s dull and grey this morning, with a weather forecast that’s predicting rain at 11am, getting heavier as the day goes on. No flying this week then, so I’ve posted the video I took last week of my new 50g quadcopter’s first outdoor flight. The effect of the Sun and the mist is just fantastic.

In case you’re wondering, this is what I’m flying:

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We’ll ignore the bit at the end where I crashed it into the ground, but the throttle wasn’t picking up the thrust fast enough and the LiPo had gone by this point. The PIDs need a bit of work too, but this is still a work in progress. This one is using the HubSan 55mm blades, and I’m also going to test with some 75mm blades once I make a bigger frame. The general idea was to see how easy it is to manufacture a custom frame with everyday components and without using an expensive 3D printer. I’ve just cut out the blue acrylic using scissors and used it to sandwich some Depron. My only sticking point at the moment is how to hold the motors on. The one above is a friction fit in a bit of old plastic tube, but this requires a lot of skill and effort to make. My next evolution is going to use a slit cut into the tube so the radius can open and grip the motors without having to get the diameter exactly right. This also means using half round cups at the ends of the frame where the motor holders will be glued in. This might be too fragile, so I’ll have to see how it comes out.

I’m a bit tied up with work this week, so the only other thing I’ve done is to fix the prop adapter on my RS352. Here’s hoping for sunny and frosty next weekend instead of dull and rainy.

Halloween Drones and Lost Models

It was a bit busy this week, despite the very windy conditions. When I arrived there was someone just leaving who I hadn’t seen for over a year. Apparently he’s been coming up and flying his foam beginners F3A style model and leaving before 09:30, so we’ve been missing each other. Then I got to do the maiden flight of an Ares UMX Taylorcraft. This is a lovely little aircraft, which flew straight out of my hand and handled the now quite breezy conditions very well. It’s just like the Champ I’ve flown, but feels a lot more solid in the air. We think it’s a bit bigger than the Champ and the motor is a longer can version, which should give more torque. Anyway, the flight was over much too quickly, despite finding time for a loop and a very bad roll with just the rudder. The landing was much better than my usual lightweight aircraft landings, actually rolling along the wheels before coming to a stop right in front of me. You usually don’t get that with this type of aircraft as there isn’t any momentum and once the wheels touch they just tip over.

Anyway, after that I had a flight with the RS352, which was followed later on by another two flights. I was mainly trying out knife edge flight and I’m starting to get the hang of the elevator/rudder coupling. I think the trick is not to try and go too straight as the rudder easily holds the nose up, but causes a curved flight path due to the pitch coupling.

After my first flight with the Taylorcraft we had a couple of drone pilots turn up. They had the idea of trying to drag a Halloween skeleton figure underneath the drone, which you can see in the video above. I’m not sure how successful this was as the wind was causing havoc with the control because of the huge sail that the drone was dragging underneath it. Landing was a bit of an issue as well. It looked rather fun though and reminded me of the DaVinci Aerial Screw, which was difficult to fly because of being top heavy. I really must make a bigger version of my prototype and try it outdoors.

The Multiplex Xeno arrived shortly after the Halloween drone had been abandoned and proceeded to fly as beautifully as ever in the gusty conditions. Then we had the Multiplex FunJet which proceeded to fly over and around us at breakneck speeds, along with the Hyperion Sniper II which got damaged the other week. A couple of guys with FPV equipped flying wings also turned up around this time, but it was at this point that the Sniper was lost over the trees on its first flight of the day. It had got blown downwind a long way and over the trees you can see in the drone video above. After that it was just an orientation and control problem which ended with it (we think) hitting the back of the tallest tree’s canopy. The three of us spent a good half an hour looking around in the trees, but failed to find any trace of the aircraft. We all thought that blipping the throttle or servos was our best shot at hearing it, but whether it was damaged, or the drone flying overhead was masking the noise, we never discovered. My opinion is that it was too high up at the top of a tree, or we were just looking in the wrong place. After going behind the tree, it could have continued to fly for quite a way if it didn’t hit anything, so it might just be sitting there now on the floor of the forest waiting for someone to discover it.

This is Autumn

It’s blowing a gale this morning. Then it started raining. The type of light misty rain that means if you have to wear glasses to see the aircraft, like I do, then you need windscreen wipers. I’ve missed three weeks running because of the weather now.

Anyway, I’ve finally covered the AutoGyro. At least I think I’ve covered it. I’ve never know an aircraft like this. Normally you cover the bottom of the fuselage, then the sides, top, bottom of wing and top. There are so many awkward bits to cover on this that it’s taken ages, plus the 35 degree ambient temperature hasn’t helped. When I put it all back together I keep finding bits to cover that I hadn’t realised needed it. The front face of the main former holding the mast is a case in point. It’s highly visible because of the cut-out for the head control rods. I didn’t know whether to do it black or the silver blue colour, so I opted for blue in the end. With all the exposed wood, I don’t know what to cover and what to leave, so I’ve just been doing a bit at a time and then seeing how it looks the next morning. This is why it’s been taking so long, but it’s been quite fun to do.

I really like the silver blue, but I think I need some white trim in places. Now I need to put all the radio gear back in and make it work again. That only leaves the balancing and covering of the blades as the last major item.

Summer Weather

This is the scene that presented itself this morning:

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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.

 

Virtual No Flying

I’ve been a bit busy with work this weekend and the weather is also quite windy, so I ended up cycling over to the flying field with nothing to fly. I was really late and didn’t arrive until about 11:30 and stayed until 12:30 hoping somebody else would turn up. In the end nobody did and I sat there playing PicaSim on my phone to amuse myself. It’s not the same as the real thing, but the weather was against it this week. I did notice, though, that the top of the flying board was missing which I don’t think was the case last week. That’s rather annoying, but we could really do with getting it fixed anyway.

The building of the autogyro is going quite well and I’ve got the radio in and the head working. I’m going to try and use an inclinometer to get all the movement angles right before cutting the pushrods to length as I don’t want to cut too much off. The pilot is glued in, so I need to figure out how to fix the canopy in place. For such a large hollow fuselage, it’s amazing how little space there is for the installation.

That’s it I’m afraid, back to work again now.

How to Make Micro Connectors

If you’re wondering how I made the 1mm ‘bullet’ style connectors for the modified HubSan X4 quadcopters, then it’s really easy to do. They’re made from 25 way D connectors that I bought on the high street from Maplin:

http://www.maplin.co.uk/p/maplin-d-sub-connector-25-way-yq48c

http://www.maplin.co.uk/p/maplin-d-sub-connector-socket-25-way-yq49d

 

First, you need to separate the shells to get at the white bit inside which holds the pins. The only thing that holds the two shells together are the ‘riveted’ holes either side. When they’re made, the holes are punched through, and it’s only this that’s holding the two halves together. To get them apart you just have to hold the metal containing the holes on the left and right with pliers, working them back and forward and also twisting to make a slot separate which you can insert a screwdriver into. Then you can use the screwdriver to lever the two halves apart. Alternatively, just cut off the hole and you can open it up.

Then separate the two white inner parts with you fingers and all the pins (or sockets) fall out.

The gold connectors then form a male and female pair which you can solder wires on to and then add 1.5mm heat shrink over for insulation and mechanical strength. I was using 15mm long heat shrink for the pins (male) and 20mm long heat shrink for the sockets (female).

Let’s be fair though, I did make 80 of these connectors, and they did work very well when tested to extremes by a class of 13 year olds. The first time you push them together they are a bit tight, but once the heat shrink has stretched they’re easy to use. We had a class of 30 connecting quadcopter motors to flight controllers without any problems. I use this technique on any small connectors that I need because it’s cheap, quick and easy to source the parts on the high street.

Flying Both Days!

It’s a bit overcast, a bit windy and there was a little bit of rain, but it was good enough to get the RS352 back in the air again this weekend. It’s been far too long since I’ve been able to fly a proper plane rather than these quadcopter things. Speaking of quadcopters, we ran the Royal Institution Coding for Year 9 session on Saturday where we gave 5 quadcopter kits to 30 year nine students (13 years old). The remains of what was left after the mass flying session is in the picture below:

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One butterfly, 2 H Frames, 2 Ghosts, 1 X Frame and the unmodified HubSan H107C. Dragonfly is still missing in action.

The kit is a modified HubSan X4 H107C with connectors soldered onto the motors and flight controller so the kids could follow the instructions and push the right motors in to the right holes with the right propellers. The frames are all 3D printed and there was a Dragonfly as well, but there was a bit of an incident. We thought this might be a problem, but the body is too thin so it broke in half, at which point one of the kids said, “shall we throw it in the bin now as it’s broken?”, to which we replied “no, we can fix it”. I’m hoping it’s still back in the office somewhere, but I can’t actually remember seeing it.

I’ve also had a play with the 0.3 mega pixel camera that’s on the unmodified HubSan. We now have 6 of these cameras, so we might do something interesting with them in the future. In addition to this, I also flew the 3D printed H Frame, which does fly more or less like the HubSan that the electronics were originally stolen from. The interesting thing is that we had 6 brand new HubSans, which I tested before modification, and they all fly slightly differently. One felt a lot more powerful than the others and was a lot twitchier, so, whether this is quality control or different settings, I don’t know. One other thing I did notice though was that a lot of the motor housings were cracked and broken. At first I thought that I was doing this taking the motors out, but they are definitely cracked as delivered, so quality is a bit of an issue here.

Anyway, despite the fact that I now need to sleep for about a week, Sunday looked like the first flyable day in about a month, so I headed off with the RS352. When I got to the field there was an Inspire flying and another guy was already there with his Phantom and a much more impressive FlyBaby that flew great. Apart from the EFlite Advance and some people with what looked like a HobbyZone box who decided to fly on their own at one corner of the field, there was also another guy with his two kids, a Sukhoi, various small foam planes and a DJI Phantom 3. It was this Phantom 3 which caused the argument about what constitutes safe flying as he was being an idiot. Apart from putting it right in the middle of all our planes and insisting that it was a good idea to take off and land inches away from the planes and us, he was flying FPV without a spotter and going to extreme distances. First he went over into the other field and tried to hit the trees over the roundabout by hovering just feet away from the branches (it was quite gusty), he then went a long way out over some more trees, along the other side of the road, then back and over the tree line where the microwave link is at the edge of the field where we keep losing models. Unfortunately, not his this time, as it’s not often I say that I would have been very happy for him to lose his model and not find it again. He actually went behind the trees and down so there was no line of sight. After he landed we tried to point out to him that this is illegal in this country (I think he’s Italian from the accent), but all he did was proceed to tell me how reliable the iPhone attached to his DJI transmitter and FPV kit was. Despite pointing out that we gave him 50/50 at the point when he went behind the trees and if they were wet and had leaves on then both his 5.8GHZ video link and 2.4GHZ radio link would have failed, but he just said that he had a magic button that brought it back. When I pointed out that his magic button sent a 2.4GHZ signal that might not get through, he just said that it would return to home on its own. We’re not sure if it would actually have cleared the trees, but pointing out that this still relies on the GPS, which can fail, he tries to tell me that they never fail and that he knows a lot more about them than me. Never a good idea to do that, especially when he then tries to say that he has a signal strength meter on his phone, I mention RSSI and he doesn’t know what it is. He also doesn’t seem to appreciate that it can also fail instantaneously if you go behind an object like a tree. An interesting point here was that he wasn’t even using a circular polarisation antenna, just the standard DJI one. I saw some kit on the BBC the other night where they had the exact same DJI Phantom, but had replaced the standard antenna with a circular one and a patch. I’m so annoyed by his attitude that I might even take my FPV kit with me next time and jam his if he turns up again. Anyway, on his next flight he was still insisting on taking off from the middle of us when it tipped over and landed on two of the props. Unfortunately the aircraft was still unharmed.

OK, that’s enough getting annoyed about quadcopter FPV idiots, I had two flights with the RS352, had a really nice chat with some American tourists and their two children who were very interested in the aircraft and loved the story about the Coding for Year 9s session with the quadcopters yesterday, then my motor shaft broke on my second landing. This was really weird because I was going to hand launch and it felt like all the thrust was pulling downwards, so I aborted to check the aircraft over. Everything was fine, went to launch again and everything was normal, so off I went thinking it was probably just the wind. At the end of the flight I felt that the power was dropping off very early (4 mins instead of 8), then it started to get very unstable one turn from finals. Now, with no power and a very twitchy aircraft, I put it down on its wheels, wing tip and spinner a fair way away as it tip stalled to the right close to the ground with no power to get out. It was also quite windy, so I was thinking that it was the wind at this point, plus a battery not used for a while, even if I did peak it before flying. On getting to the aircraft, I could see immediately that the motor shaft had sheared clean off at the bearings in the front of the motor. The prop was still in one piece and attached to the adapter, which still had a cleanly sheared bit of the motor shaft inside it. My thinking is that this must have happened in the air and my aborted first launch was a symptom of the shaft not running straight. Then the loss of power and handling problems were the shaft in the process of shearing, finished off by dumping it into the earth. I just can’t see a 3mm shaft breaking like that and leaving the prop intact. It’s probably all these high torque and gyroscopic reactions which caused the fatigue in the first place, but this is the first time I’ve ever seen this happen. Oh, well, I’ll just have to get a new shaft and try and extract the motor.

After breaking the RS352, I then went and had a go with the HubSan X4 H107C with its 0.3 megapixel camera. Watching the video of this back is really interesting, but I should really have been concentrating on what I was filming and not talking to the guy next to me. You get a lot of shots of grass, but it’s the take off and landing that really gets me.

It’s interesting to see the video, but you really need the new high resolution camera to get the best out of it. It’s probably better indoors, although the stop start button for the recording is a bit fiddly and you never really know if you’ll get a recording.

One final thing, but on our way home we saw another person flying a small white trainer type aircraft (badly) in the wrong field. I hope somebody points him in our direction for next week.

Right, I’m off to fix a motor shaft and build and autogyro.