The Last Sunday Before it’s Illegal

This is the last Sunday before the DRES regulations come into effect at the end of the month, so it’s the last opportunity to fly legally without an Operator ID on the aircraft. Well, actually it isn’t really, because BMFA members have an exemption until the end of the year, but I’ve got mine anyway.

When I got up this morning it was a little bit misty, which then got worse. As it’s always ten times worse when you’re standing in a field in the middle of nowhere, flying didn’t seem like a good idea. In fact, there was a moisture in the air from the mist that was making everything sopping wet. It wasn’t nice this morning, up until lunchtime when we had about an hour of sunshine before it went straight back to grey and murky again.

The picture you see at the top of this post is something that I’ve been working on all week. It’s a 3D printed drone racing gate as I’m attempting to replicate the Drone Racing League and Lockheed Martin’s Alpha Pilot competition, but done my way using micro drones and much cheaper technology. I’ve been all week designing gate bits that fit together in Fusion360 and I have to say that I’m starting to get the hang of CAD a bit more. Maybe I just needed to start with something simpler than a WACO SRE biplane? The gate above is modular, being composed of 12 straight sections and 8 angle joints of 45 degrees. It’s isn’t a regular octagon as I’ve made two sizes of straight section – one 9cm and one 12cm. The 9cm sections are the horizontal and vertical pieces while the 12cm sections are the diagonals. The beauty of this design is that each piece takes about an hour to 3D print and you can make different variants of square and octagonal gates by plugging different sections together. I’ve made a selection of 45 degree (octagon) joints, 90 degree (square) joints and 180 degree (straight) joints for extending the sides to make a bigger shape. There’s a limit to how big you can print on the 3D printer, so the ability to extend sections is very useful.

I found that the gate in the picture was a bit small for a 100mm quadcopter, although I did manage to fly through it without hitting anything on my very first attempt. After adding some more sections, the aperture is now 40cm across, which is about three times the width of the quadcopter. This seems like quite a nice size, so I think I’ll stick with it.

Having built my obstacle, the next challenge is to add some markers and build a computer vision system that can pick the flyable region out of an FPV camera frame. First off, I’m going to add my markers and take lots of shots of the gate in order to build myself a training set. I haven’t quite worked out how best to do this yet, so I’ll have to leave the details until later.

The other part of the plan requires being able to fly the quadcopter from software running on my laptop. This needs a FrSky XJT module connected up to the computer, but this is fairly standard and shouldn’t present any problems. I’ll be ordering the XJT module later this evening, so I’ll have some electronics to do later this week. The thing that’s worrying me is how much latency there is between the video being presented to the computer and it being digitised and processed. Humans have about a 200ms latency and the video that the computer sees is always going to be a bit behind real life, even with a low latency FPV camera. My theory is that the computer can see exactly what a real drone pilot sees through the goggles, so any other latency is down to the video digitisation and processing. I guess I’ll just have to experiment and see how it goes.

Anyway, that’s it for now. I’m off to put Operator ID labels on all my planes ready for December 1st.

Crazy Day

The weather was pretty much perfect this weekend. No wind, not too cold in the bright sunshine and just a hint of mist. Everybody seemed to be out and about and there were people and cars everywhere. Roadworks, traffic jams and other events seemed to be the order of the day.

I even saw Father Christmas!

I think he’s picking his reindeer for this year’s delivery

As for the flying, I was the only one there for about an hour and managed to get two flights in all on my own. Then they guy with the black high wing Hobby King tricycle pusher with the ultra bright red LED in the nose turned up. I think this is a sort of modern day equivalent of Rudolph. After that a guy with a really good UMX sized P51 Mustang that he bought online arrived and had a few flights. He was having problems with it suddenly losing all power and control for no apparent reason. This might be battery related, but he was having intermittent problems all morning. It flew beautifully though, with stabilisation and everything. Next up we had someone with a small helicopter. I haven’t seen one of these fly in quite a while, as the drones seem to have absorbed the small helicopter market. He could fly it too. It’s a very different look when you see a helicopter fly compared to a drone. It’s something about the large rotor being much more visible than four small ones, plus the pod and boom giving it some shape. Finally, there was a couple at the extreme edge of the field flying another small high wing trainer, but we never got to talk to them.

In terms of flying, I managed to do a bit of trimming and I’ve decided that my thrust line is wrong. I need to bring the motor down a degree or two, so I must make that modification using a spacer this afternoon before I forget. I also had some binding issues like I had the last time. On my second flight the radio wouldn’t initialise, but this time I noticed that the transmitter’s “beep beep beeeeeeep”, was different to normal. I’m wondering if the issue stems from the transmitter, rather than the aircraft. It’s a Futaba Field Force 8, which is about 20 years old that I use with a TM-7 2.4GHz module and FASST. I switched the transmitter off, then back on again, got the right beeps and the aircraft worked fine. I’ve never heard it do that before, so it’s a new one on me. I think I need to ask Santa for new radio for Christmas. The FF8 has had a good run, but it’s about time. I’ve also been having problems with charging and the balance connectors on my new batteries appearing to not connect to the charger reliably. I keep getting battery not connected warnings from both the chargers I use, which is really odd. I need to do some more investigation into this as the hand-held battery meter works fine. Also, my 12 volt field charging battery is almost dead. It’s also probably at least 20 years old, in fact I think it’s older than my radio. When Maplin was around you could just walk in and buy one, but I think Halfords might be my best bet on the high street now. Buying one mail order seems like a bit of an issue with the weight.

Anyway, technical problems aside, I had four good flights this morning (I would have had five if the charger was working). I practised lots of big easy Cuban eights and some prop hanging. On one attempt I managed a really good hang where the aircraft held itself in the vertical and slowly span around the rudder axis. I just let it spin rather than trying to null it out, as it look really rather good. Then I messed it up with my third landing. Coming in a little too fast and trying to scrub speed at too low a level, I managed to find a bump in the ground. This stopped one of the wheels, but the other wheel didn’t get the message and I ended up rolling over right with the fin overtaking the wheels to end up upside down on the grass. It all happened at almost zero speed, so nothing was damaged.

Well, I managed to get in a lot of flying practice this week, so I now feel a lot better. Let’s hope next week is just as good.

Remembrance Sunday 2019

I wasn’t planning on flying this weekend, and the weather was somewhere in between flyable and not flyable. It was bright and sunny when I got up because we’re in the middle of a big high pressure zone. Unfortunately, we had torrential rain yesterday, so everything is now flooded, and the main reason it was sunny this morning was that the wind had blown most of the clouds away.

Anyway, I’ve made some progress with the mini Lidar that I’ve been experimenting with. I haven’t got it to work yet, mainly because of the micro molex connectors, but it’s taken me the whole week to figure out which one of the many variants I actually have. This is my biggest problem with Chinese electronics from Amazon – you never really know what you’re getting. Apparently, I have the MakerHawk variant of the Benewake TF-Mini Lidar, which is the UART device, as opposed to the I2C version, and is LV TTL, which means low voltage TTL (i.e. 3.3v), which is directly compatible with an Arduino. Now that I’ve written this down, I’m starting to doubt myself, but their example wires it directly to an Arduino without the TTL level converter that the SparkFun example uses. I’m going to check it again before I blow something up, but it’s really not easy figuring out what you actually have.

In addition to the Lidar, I’ve also been designing micro FPV racing gates in Fusion 360. I realised in the end that trying to copy a standard aluminium welded gantry design with 3D printing was a waste of effort. It takes a lot of effort to design, ages to print and isn’t the best method. Instead, I designed a solid model which will print faster and be stronger in the finished article. The idea is to make a modular design, so I have 20 centimetre long pieces connected with 180 degree and 90 degree joints for square gates, plus a 45 degree joint for octagonal gates. We’ll just have to print some bits now and see if it all fits together. I seriously doubt it given past experience in 3D printing, but I need to do some test prints before doing any more work on the fixing and locking mechanism. After that I’m going to look at the electronics needed for a micro AI racer to fly through my racing gates.

Finally, now that the CAA DRES (Drone Registration) scheme has launched I’ve got my Flyer ID and my Operator ID. Technically, I’m covered by the BMFA exemption, but I wanted to see how it worked, so I gave them my £9. It’s complete rubbish. I complained and got a completely useless answer back. All the questions are geared towards multi-rotors, so I asked about the one where it asks what you should do if you fly your drone into the sun and can’t see it. Their answer is that you should fly it backwards towards yourself until you have it in sight again. My point that I made to them is that my scale Avro 504K can’t fly backwards. Basically, you shouldn’t get yourself into that situation in the first place. Also, there’s the old trick of closing one eye when you’re in the sun so that you can use the other one to see as you come out. Anyway, I still haven’t managed to get them to answer the question, “does an ekranoplan need to be registered?”. And what defines a drone anyway?

I haven’t been able to do much this week due to work, so let’s hope the weather is good next week.

I Beat the Weather

It’s the RS352 again this weekend

After yesterday’s 60mph winds and rain, I was a bit reluctant to believe that flying was going to be possible this weekend. However, Sunday dawned bright and clear with blue skies, high level wispy clouds and no wind. I didn’t know at the time, but there was about a four hour window of flyable weather and I used it perfectly. When I arrived at the flying field it was still bright and sunny, but it deteriorated over the next hour or so to overcast, with a moment or two of very light drizzle in the air. Towards lunch time it was getting worse as I packed up to go home, followed some really quite heavy rain when I was safely back indoors. Perfect timing.

• 

• 

These are the two aircraft that I flew this morning. There’s quite a size difference!

I was the first to arrive this morning, but I was closely followed by my friend on his bike with the small aircraft in the picture above. This was the one that his son told me last week that he thought was evil. I had a flight on my own RS352, then followed that with the small Volantex Trainstar. It flies OK, but does seriously need that rudder turned down a lot. I just spent the whole flight trying to keep it in the air while it spent the whole flight trying to spiral itself into the ground. Seriously, though, if it was set up correctly it probably wouldn’t be too bad. The Horizon Champ was ten times better though.

We also had three guys with drones arrive, one of which was 3D printed in bright orange (you can just see it in my picture above). Talking to them was very interesting as one of his friends is a display pilot for very large RC aerobatic planes. After seeing me with the RS352 he’s now thinking about getting a proper aircraft. We also had the guy with the DJI Inspire who was up last week, plus the other guy from last week, but with a different plane. Last week he had the black painted Hobby King Easy Star look-alike, but this time it was a foam high wing cub type aircraft with huge Tundra tyres. These proved to be its downfall as the undercarriage axle broke and he couldn’t fly it.

Anyway, as for the flying with the RS352, the trim was completely wrong for some reason. I’m wondering whether it’s the new LiPo packs, as they’re about 104g compared to the 100g of the old packs. What I’m seeing is the extra power from the new packs resulting in it wanting to head for the clouds with the nose in the air. It was really hard to find the “sweet spot” where it flew level happily without any control inputs. I was constantly correcting with up and down elevator trying to fly level. This is really not great when you’re trying to land, but I managed four flights of moderate aerobatics, not worrying about trimming as I needed to get some stick time on this aircraft. I haven’t flown it that much recently because of the weather, so I wanted some practice. Add to this the flight with the Trainstar and I probably had about 40 minutes air time this morning. Actually, I have a small confession to make. Now I think about it, I had 5 flights with the RS352, but only because I got the packs confused on the final flight and flew with an already used pack. Considering that I’d previously done seven minutes on it, it faired rather well and I certainly couldn’t be sure immediately that it was discharged. The launch was good, but it just didn’t have the same punch. So I landed and swapped packs and had another good seven minute flight. I shouldn’t make stupid mistakes like that as you don’t always get away with it so easily.

One other thing worried me this morning, but I had a re-occurrence of the binding problem that I last had over a year ago. On my first flight with the RS352 it all powered up correctly and I got the customary “beep, beep, beep… … beep” from the ESC to tell me that all was well. Then, going through my control check, I noticed that the flaps hadn’t dropped. And all the controls were then unresponsive. I disconnected the LiPo, reconnected it and the ESC failed to initialise, showing no signal from the Rx. I tried another battery – no difference. I fiddled around with the connectors – no difference. Then it just started working again. That’s really worrying and left me with the question, “what was the problem and am I safe to fly?”. Now, the Futaba FASST system that I use is absolutely rock solid. The last time I had this problem, there was a DJI Mavic, and you have to wonder if this is related as there was another drone being used close by (not sure it was a DJI though) and we know that the DJI radio system and the Futaba FASST system are very similar. Anyway, it looked like a binding on power up issue to me. I can’t explain why. We did a full range test, tested the controls for 10 minutes on the ground. There were no problems at all, not even a glitch, so I decided to fly. I had four (OK, five) flights with not a single glitch, so it’s very odd.

Anyway, that’s all the flying for this week. Now that the rain has come back I’m off to play with my 6g LIDAR sensor that I want to attach to a micro drone. I’ve been meaning to get this working for ages, so now is the time.