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Wednesday, June 15, 2016

Quadcopter

I'm flying! Well, I'm a pilot, but not onboard. Radio controlled (R/C) Quadcopters have intrigued me for a while and I've played a bit with other peoples' - a couple of DJI Phantoms outside, and a small toy twin-rotor helicopter inside a work office (doesn't really count). So recently I did some research and picked a mini-quad sized "drone" (preferring not to call them that now after my reading) at the toy end of the budget scale, but a level up from the cheapest available. Better to learn and crash on a cheaper smaller one that can't do so much damage (to my pocket, my stuff, or myself - or anyone else). After a few evenings watching reviews around the price point I'm considering (and of course lusting after posher and more specialist ones sometimes!), I felt I'd picked up enough about the current market and what to expect for your money that I could make a good choice.

So, folks, this (pic below), is the Pioneer UFO, model JXD 510G (one of the best prices at GearBest as linked to, look for deals). Having had it long enough now to crash it quite a few times, flying it indoors and outdoors and starting to get a little used to flying it (still a long way to go before I'm an expert), I thought I'd write a review of it as I think its a great choice for what I wanted. There were no financial incentives to write it when I did, so its an honest review, I bought it at the full price (as it was in May on a sale) with my own money (from my last birthday).

I think the 510G looks pretty cool, and it has a slightly different look to its previous version model, the 509G, being a little more aggressive and futuristic, alien like. But the main frame around the central body is still pretty much the same design and size and it seems designed for structural strength with all those crosspieces, and the legs are curved (towards you in this product photo) and somewhat flexible. What do you think?


Pioneer UFO JXD 510G "X-Predator" model quadcopter body photo


The camera is pointing at us in this view just below that pointy fang-like snout. It is very black apart from the bright green detailing lines along the top outside edge of the body and logo on the "canopy" (as it would be if it were a plane).

It is fantastic value (for the current state of the market in mid-2016), as a mini quadcopter with 5.8GHz FPV (First Person View, where you get to see what a pilot on the 'copter would see) via a cheap camera/transmitter and provided receiver/screen, automatic altitude hold if no throttle input - using an internal barometer, and all the usual standards of basically any cheap quadcopter with a camera out there at the moment.

"usual standards" means that can do flips in any direction with a simple button+stick-input combination, comes with headless mode (that sometimes works), different speed modes for beginner/advanced (or just coping with a bit of wind), "1 key return" (which is totally unreliable), has trim adjustments on the transmitter, buttons for taking photos/recording video (all recorded to a micro-SD card on the 'copter), and LEDs that blink when the battery is low.

Batteries. Ah, yes.. The scourge of R/C model fliers everywhere. Current battery technology places a limit on how long you can fly and this 'copter comes with a single 650mAh battery that will give you maybe 5 minutes of flight or so. If you want longer, then you should buy more - gearbest have a pack of 5 @ 850mAh batteries and a charger (using the Losi type awkward white flat connectors, but it comes with converters to the nicer long-thin JST type I just leave permanently attached to the charger) that fit (and specified to in the product title) with just enough space left to pack the connector plug in to the space left for the battery, for a good price. I'd strongly recommend you pick this up (or equivalent guaranteed to fit) if this drone takes your fancy - or even 950mAh if you can match the right size for it. In fact for any drone, if you can switch batteries without taking it to bits with tools, then buy some extras at the same time as you buy the drone, most definitely for toy grade ones. Not being able to switch batteries is annoying as it takes a while to recharge them and flight time per battery is never good enough on the standard batteries usually supplied. Unless they're big enough to do 15 minutes or half an hour or so (about the most you get in one go on any R/C copter), you'll always wish you had more power to fly it with at the end of a flight.

The FPV screen included for the 510G (obviously not for the wifi version) is pretty basic but behaves nicely - ie. when signal reception is struggling it gradually fills with static before dropping out, with no sudden blackout, and it seems to almost match the range of the 'copter controlling signal too. The screen has a pop-up sunscreen guard box around it that folds away nicely, and is supplied with a screw-in linear-type aerial (so you could change it for the clover-leaf type suitable for 5.8GHz if you wanted) but is unfortunately locked to one frequency so you can't use it to watch someone else's FPV video on a different frequency. The video transmitter is also linear and is a flexible wire popping out of one of the camera module's cooling holes (with a rubber protector on the end), not a screw fitting.

Altitude hold feature is the new hotness feature to have on cheap drones this year, having filtered down from the expensive GPS drones which have full position-hold. This means it keeps the height the same if you're not touching the throttle input, and also means the throttle stick (the left one for mode 2 which this is locked to I believe) springs back to the middle position to allow both up and down movement from the central no-input default position. This means the craft is much more easy to keep stable than pure throttle-input control as you only (in theory) need to adjust for any wind in a horizontal/yawing direction to keep it at the same position and you won't accidentally get too low or too high. It does work very well, and is much easier than keeping a steady throttle yourself (where if you let go or knock it you could drop or shoot off up into the sky without an idea what position you left it in before). It has a barometer to enable this - thats the same way the expensive ones (eg. DJI Phantom) do it. If the atmospheric pressure changes while you're flying this can affect it so I've seen it drop and hold a new height but this doesn't happen very 

The one-button flips in any direction (standard on everything nowadays) cause quite a drop afterwards of maybe 3 foot/1 metre, as it does for other non-acrobatic flyers, but it does raise up a bit as it starts the flip so its a bit more centered around the previous position. Some other models with this wide a flip space don't end up the same height they were before, but with the altitude hold it does do a good job of remembering the original height and returning to it after the flip as long as you allow it to - though it can take a couple of seconds. It will refuse to flip if the batteries are low or if its so windy that its struggling to keep itself level in that direction (I think, unless that was low battery situation too). Camera drones aren't intended to be as acrobatic as racers and while flips are impressive to the general public, anyone who's flown a drone recently will be aware its a single-button manoeuvre so it isn't as impressive as it used to be if you're trying to show off your pilot skills.

The included camera isn't very high quality, I think it quotes 2Megapixels, but its enough to do FPV with and relatively lag-free (Wifi FPV modes will always lag more than analog FPV which this is, due to 1: compression into a digital video stream, 2: sending the feed as TCP/IP packets rather than raw image information, 3: decompression the other end and only then displaying the image).

The 510G (and 509G older version before it - why didn't they work to fix that among the other improvements) suffers from "Jello" as the Americans call it, which means a wobbling camera that could make you feel ill after watching the view for a long time. The jello effect is a bit like watching heat haze, with horizontal bands on the video that aren't aligned with the rest and that move through the image. This problem can luckily be fixed using some foam between the camera "ball" and the model's body, and optionally moving the camera backwards a bit too. One way to try this is to not use the original slot and hold the camera unit onto the body with rubber bands instead (link to 4m7s into this video shows the best-solution fix from any youtube video I've seen so far): https://youtu.be/YPEaWezm7Sw?t=4m7s
However I have been happy with just a bit of sturdy foam placed around the neck (just behind the camera swivel) of the camera unit, the jello is not 100% gone but its very much improved and good enough for my use (when I'm flying LoS a lot of the time). Or of course by removing the camera for a flight which would give you longer flight time and more responsive and faster control of the craft due to less weight. In bigger spaces I've always kept the camera on just in case I lose where I am, though I still fly LoS (Line of Sight) with perhaps the odd glance at the screen to check its rotated the way I think it is if its further away - thats a good way of pointing exactly in a direction as you can see whats in the middle point of the screen and where you're thus headed.


I was wondering how similar this mini-quad 5.8GHz FPV version is to the Wifi FPV version, as it has 2 sockets on the base of the body - one for FPV and one for WiFi, and they're the same socket type. Does it even include the wifi technology just unused for this version? Well I tried switching the plug over, and it doesn't seem to. At least, I can't see a wifi access point created once its calibrated its gyros on power-up. I can't control it from the provided transmitter I think, but it doesn't break anything to try that - if I switch the plug back again it carries on working just fine as it was before. I'm happy with the 5.8GHz FPV, as WiFi FPV is always more laggy and usually delayed enough to make it harder to control in FPV mode only (especially if flying in close proximity to any obstacles), besides taking over your smartphone while using it and drawing its battery and stopping you doing anything else online meanwhile).

One quality I was very impressed by both in reviews and since I've had it, is how indestructible this quad is. The legs are pretty flexible and can take some hard landings. I have broken one of mine after a fall from ~20ft (estimate) onto hard ground landed awkwardly but they'll put up with a lot of abuse and I think once glued back and strengthened a bit (bit of wire glued into the structure on the inside of the leg across the break, and filled in sections with superglue-cement), mine are now good again. The propeller blades are quite flexible and obviously intended for beginners as you can smack them into walls and other hard things repeatedly without breaking them. In fact I don't know why I bothered ordering another set of propellers - something recommended to new R/C model fliers across the board by experienced folk, but I've been "trying hard" to break them both inside and out, and not managed anything more than scuff marks so far over a few weeks. It comes with one spare set already anyway. The prop-guards are cheap flimsy affairs however and after several crashes will tend to get a bit bent. After a while of this they'll bend so much they will start getting in the way of the propellers (rotors). You can bend them back a bit but I didn't fancy their chances of long-term survival so I just took them off and let the propellers take the damage for now. Maybe I can find some alternate stronger ones from another similar model, or get my own design 3d-printed or something? Some people on a couple of reviews I watched complained that they fall off easily but I think those people just pushed them on and didn't screw them in - there's one tiny screw in the smaller of the holes on each guard that screws into the body once they're clicked in place (ignore the 2 slightly larger holes). Careful to put them on the right way round, the propellers and prop-guards are marked A/B to match letters printed on the frame next to the motors.

As a beginner pilot, the drone will get knocked around as you bump into things (be careful and don't make those things be other people - fly clear of people, keep eyes open for people entering into your flight area or near it - spinning propellors can cause injuries and even just falling drones could cause harm or shock that could knock someone over, if something unexpected happens you don't know where bits will fly off to). Hence why this 510G is a great beginner's learner FPV model. If it takes a small knock you can recover and fly away if you have a little skill. Bigger knocks (especially ones that cause it to topple/block a blade from spinning by getting caught on something) will automatically cause it to go into safe mode, cutting the propellers and turning it all off, hence when it will fall to the ground and you'll need to reset the transmitter and drone by going through the full off/on sequence. You'll lose any video you've been recording and the FPV will stop too. This is somewhat annoying if you didn't see where it fell as you can't use the FPV video screen to see what the camera can see and help you find it, instead you have to try and remember what the last view was before the crash or make sure you saw it fall using LoS. But I understand why they go into this "safe" mode, to avoid damage to other things or people that would likely be worse than any little damage to the drone or risk from the battery short-circuiting, or losing the drone (which isn't even that expensive to replace). You'll also get annoyed if it was a particularly long and good flight video sequence - so I suggest stopping and starting the video after each segment regularly enough to still keep enough recent flight footage. A double-tap on the "Video" button will do that (if you don't tap too fast) and you won't miss much, particularly if you're not flying fast when you do it.

After all these knocks you'll start to get scuff marks on the edges and top surface of the propellers, but it will carry on flying without any noticable loss of control. Long thin things like hair, grass and threads will love to get wrapped round prop-shafts and tie themselves into knots; remove these as soon as you notice them to keep everything running nicely and avoid having to replace the motors or cogs soon. It looks like new motors will be available easily enough if you don't mind a wait for delivery, but for drive cogs you'll need to do your own research and DIY to replace them, and I definitely don't see any individual body parts available as spares. I saw someone replace a similar model's ones with a brass cog, not sure if thats a great idea (would strip the teeth from the other plastic one connected to the motor more easily and slightly unbalance that corner).

Some reviews say it doesn't have a huge range from the transmitter, though most others say over 100m (100m/300ft is about the best any toy-grade bought-ready-to-fly mini/nano quadcopters manage at present in standard form). To be honest I doubt I'll need to worry on the range, in London suburbs there are quite limited sized spaces to fly it in anyway that are far enough away from houses and groups of people. So its flying at home inside or in the few parks that could fit a circle larger than 300m diameter to play inside that ring (the UK rules say minimum 150m away from roads/houses and obviously avoiding a large area around our airports).

After one session out on a local common, I lost it for a while when it came down amongst brambles and nettles and trees, so when I found it (before it started getting dark luckily, though after it rained a bit) I decided I'd do more to make it easy to find next time. It is very black, and therefore can be hard to spot on a dark day in dark areas of nature and greenery. It was fine afterwards by the way and flew like nothing had happened (as I said, almost indestructible!). So I made a few cosmetic modifications and one minor hardware addition:

  1. Use sticky-backed aluminium foil to make it much more reflective - combined with Christmas shiny holographic-type sticky tape in other areas.
  2. Use fluorescant sticky-backed paper tabs with tape over the top to keep it secure and more waterproof, to further help make it brighter and more visible. The top of the model already has an almost fluorescant-green line down it so I went with this and I think it still looks ok (note: I am not a designer!) I followed a pattern to help me id which way round it is when further away too. I considered buying LED strips to attach round it as an acquaintance who flies a Phantom locally has, but not planned to take this idea that far yet.
  3. Attach a proximity-detection device (with sticky-pad + rubber band as fallback, or maybe long-term switch for a twist-tie or string that won't degrade). I'm using a Lapa (v1) because I had a spare one to use, is small and light and it works with my phone which I'll usually be carrying anyway. There are tens of similar-function equivalent devices that use either Bluetooth or other radio to help you find your stuff by attaching some tiny battery-powered device to it and giving you a remote/receiver that you carry and that tells you when you're near and can usually (depending on the model) make the device beep and/or flash to narrow down where it could be. via hotter/colder directions (no direction info, none of them I've come across have GPS). This way if I lose sight of it and it crashes, if I at least have a vague idea where it is (within bluetooth range, ~60m in clear air which is plenty enough in open areas) I can use that to help locate it and it won't turn off when the thing crashes so I'll still have a way of interacting with it to find the thing. I just hope it can cope with a few Gs of crash-landing from some height, and doesn't separate before it comes to rest. I doubt the added weight will be a problem, it weighs probably less than 20 grams.
After all this, it now looks a lot brighter and more colourful...

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