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2016/08/29 RC Flights over Burning Man, 2016 edition
π 2016-08-29 00:00 in Bm, Rc
It was my dream to do something like this since my first burn in 2002 (you can read my BM reports here: http://marc.merlins.org/perso/bm/ ), and I had my first shot at it the previous year, but despite a lot of preparation, not everything was perfect with my RC aircraft last year. Namely, last year:
  • I had a small bug which prevented using fly by wire modes while flying in a nice straight line for filming (they otherwise worked fine for safety and return to land, just not for filming)
  • I had a big motor glider with a front propeller (larger prop that is more efficient), but sadly it of course showed up in the front camera view
  • Video was 1080p, when I really wanted 4K, but I just wasn't able to put a 4K GoPro on my BFG2600, while I was able to fit one in the front nose of my Sky Eye since it uses a rear prop.
  • Please read the Q&A section at the bottom if you are thinking about flying a drone at burning man. Drones are restricted and require a permit.

    So this year, I took my newer Hobbyking Sky Eye after much testing, and it had these pluses, with extra safety features I added:

  • Newer version of the pixhawk ardupilot firmware with working FBWA and CRUISE modes including firmware that could recover from upside down flight
  • Smaller aircraft than last year with less weight and less kinetic energy just in case somehow it were to crash (with still enough room to carry all the electronics and cameras)
  • Autopilot had redundant sensors, along with a complex EKF filter that can detect bad sensors and fly without them
  • Triple redundant radio link to control the aircraft, with again the autopilot bring the airplane back on its own if all the radio links are lost. Radio control range was more or less 20km, way more than necessary for extra safety
  • The autopilot takes over if radio signal is lost anyway
  • The autopilot also takes over if the aircraft flies too low (altitude deck). This did unfortunately lead to pictures that didn't have some art big enough in the picture, but it was tradeoff for the safety afforded by extra altitude (as a reminder, you usually would want to keep the altitude low-ish to avoid conflicting with full size traffic typically at 1000ft AGL and higher, but in this case, flying within the trash fence is actually safe since it's restricted airspace for full size aircraft).
  • The autopilot and aircraft obviously continue to fly for quite a while without engine power if the motor dies or the battery were allowed to run low (and there are multiple warnings and radio downlinks to prevent running the batteries low).
  • While this aircraft has a pusher prop to allow for the front 4K unobstructed camera view, I upgraded the powertrain to provide 800W peak and ability to fly up to 120km/h in case of bad winds. One flight after a storm had winds up to 60km/h, so this extra power capacity was not superfluous. The average drone could have been blown off and unable to come back in that much wind while my plane was able to fly against it without problems, just extra battery draw.
  • AP throttle controlled modes like RTL were modified to maintain a minimal ground speed even in very heavy winds (some other auto pilots will not notice and kill the batteries flying with insufficient throttle against high winds and fail to return to home).
  • In prior high speed stress testing at home, I was able to get the wings to fly off the plane under high load at full speed, causing an unfortunate crash, so thanks to that prior testing, I was able to build an new aircraft with re-enforced wings to avoid further crashes. Obviously this is the kind of testing and fixes you want to do at home in a safe place, not at burning man.
  • But as a nutshell, on top of having 4K video in the front (but only 2K in the rear), plus a 3rd camera on the top in case the 2 recording camera failed, this plane was packed with electronics that are sadly more capable than most airliners out there, and it had a lot of extra power to deal with the low density altitude (up to 33% less performance due to the thinner air) and be able to fly out of a heavy storm and come back to a safe landing (the last day, it indeed flew against a 60kph+ wind and even landed with a negative ground speed, i.e. while going backwards). While it was also able to glide for extended periods of time without power, it had a lot of battery capacity to allow flying for 45mn or more in ideal conditions.
  • Yes, I realize that this plane does not yield nice steady shots like what you'd get from a drone, but I very much favour versatility and safety over better video, sorry if you were expecting drone-like super steady pans from the air :)
  • Best of day flights:


    Best of sunset/night flights:

    Here is a page describing my HK Sky Eye Build:

    testing/showing off the video to a friend during preflight checks and tests
    testing/showing off the video to a friend during preflight checks and tests

    Pictures from the sky

    you can see from the dust that the wind is often strong, even in the morning
    you can see from the dust that the wind is often strong, even in the morning



    red lightning
    red lightning





    lighthouse
    lighthouse

    pyramids
    pyramids

    poor robot :)
    poor robot :)









    there was a big parade of bikes going by
    there was a big parade of bikes going by


    Then, I got super lucky with a sunset to night flight:








    sunset turned to night:




    art car ring around the man after a heavy storm
    art car ring around the man after a heavy storm


    Questions and Answers

    RC planes vs Drones:
    While BM is interested in heavily controlling drones, it does not seem to care about RC planes since not a single one was licensed through the process that seemed meant for drones and both BLM ranger I asked, as well as a BMorg person both told me that their concern and worry were drones. I do support BM restricting the amount of drones to a some pre screened ones operated by trained and responsible pilots, given that drones are way more dangerous than foam RC planes if they fail and fall, and it's way too easy for people without a clue to fly them wrecklessly
    Also, putting aside the total absence of glide ratio on a drone, no off the shelf drone I've seen has as many redundancies and safeties as my plane had, so it makes sense to restrict them to areas with a perimeter so that no one gets hurt should one suddenly fail and drop like a stone (RC planes are very unlikely to just fall straight down from the sky unless they break up in flight, so a perimeter doesn't make much sense for them. Also, when they are made out of foam, they are much less likely to cause injury to others, or worse. On the flipside, drones are much easier to fly and yield better video, but personally I'm more interested in safety than image quality.

    For the rest, please read my Q&A from last year, but like last year, the pilots and ground spotters will remain anonymous for a variety of reasons explained there, although they were properly licensed to fly RC as per the FAA's requirements and as already explained employed multiple methods to maximize safety.

    This shows the autopilot applying 72% power (i.e. power reserve left to get 88kph airspeed, and only 45kph ground speed during a very heavy 61kph headwind, the highest I had flown against so far). This used only 250 Watts out of a maximum of 800W available in case of real need:




    Tips and recommendations for RC flyers

  • Like last year, I beg non expert pilots not to fly at burning man without proper training and permission if you are flying a drone. BM is not a place for you to learn to fly or get to try this new toy you just bought and didn't spend weeks or months building and testing yourself (including its failure modes like low battery, RF being shutoff and so forth).
  • My aircraft description and its safeties, including months of building and testing, should make it clear that even flying a foam airplane without a propeller in the front, is still serious business if there is any chance you could crash into people, so you really need to know what you're doing and have a very reliable, very tested aircraft with as many redundancies as possible, and obviously you should still refrain from flying at low altitude over people outside of what's required for takeoff and landing.
  • If I'm being that cautious about flying a foam RC plane, you'll understand that I just wouldn't want to fly a drone at burning man in any other fashion than a ladder over a perimeter that's been cleared of people in case the drone fails and falls out of the sky. This is why drone usage is heavily restricted at burning man, for everyone's safety.
  • Please read the rest of my tips from last year
  • last, but not least, if you don't have your full contact info on your aircraft because you're scared of what might happen if you crash and someone else finds it, please don't fly. Thank you :)
  • 2016/08/05 120kph Capable HK Sky Eye FPV build with Pixhawk/Ardupilot 3.5
    π 2016-08-05 00:00 in Rc
    I needed a new plane for my plans of overflying and filming burning man 2016 with 4K resolution, and I ended up choosing the HK Sky Eye for this job (follow the link for the result)

    My BFG2600 was my big range, big load FPV platform so far. It's a great platform, but as big as the plane is (2.6m), the cargo bay is not actually that huge, and it's totally packed with electronics, to a point that it's hard not to have them conflict with one another.
    The next problem with the BFG is the front propeller, making it hard to get forward facing video without getting the prop in the way (even if it's actually capable of gliding for quite a while without motor power and with the prop folded). Related to this, I wanted to switch to 4K video, and fitting a 4K camera in the plane, preferably forward facing, and without sticking it out the plane where it would foil airflow, didn't seem to be very possible.

    So, the previous year I had tried the X-UAV Talon but while it looked good on paper, it was a bit of a handful to fly, and it meant more for long range FPV at high speed than low speed loitering and filming, and due to its wing design and wing loading, it needs a pretty long runway for landing, so it's not ideal for difficult terrain.
    Enter the Sky Eye, which is a good compromize between the two by having a pusher prop which is sadly not in the rear like the X-UAV, but still allows decent power (more than 600W if needed), and it comes with an open view front dome:


    Power Upgrade

    Here are some details on my build. While it comes ARF, I trashed the undersized ESC which I wasn't going to trust and wasn't compatible with a 4S setup anyway (3S was not going to yield enough power for my needs), and while the stock motor did work on the bench, I was not going to trust it to output 700W on 4S when it's rated for 430W on a good day.
    So I used a Castle Edge 50 which I knew I could trust and had data logging, along with a bigger motor: NTM 3542 1250KV, 700W/50A peak. The stock setup allows 50-60kph, while my upgraded setup allowed 120kh, which is way safer when flying in high winds.

    I'm currently using an aeronaut cam 8x6 prop (8x7 works too but needs a bit more of a throw), and it's making plenty of power
    Here's a quick table I wrote then choosing motors and props:

    Stock motor, 3536  1200kv, 430W/30A max
    RPM     Watt	meterV meterA	
    12500	295W	11.8V  25A	3S, 8x6, 50-60pkh?
    15000	540W	14.8V  38A	4S, 8x6 (>max allowable power 30A/430W)
    	690W	15.0V  46A	4S, 8.5x6 (way over max allowable amps), 110kph+
    

    NTM 3542 1250KV, 700W/50A peak RPM Watt meterV meterA 13000 250W 11.6V 21A 3S, 8x6 cam folding prop, 60kph? 12300 700W 14.4V 50A 4S, 8.5x6 prop, 60A ESC cutoff 10600 500W 15.0V 33A 4S, 8x6 cam folding prop, 110kph

    The space for the motor isn't that big, but I'm thankful the NTM 3542 fits in there. For prop, you can go to 8.5" and if you go to 9" or bigger you need an adapter, or you need to notch the boom, which may or may not be a great idea:


    new motor with foldable prop for gliding
    new motor with foldable prop for gliding

    Making the Airframe Safe with 100kph+ speeds

    The reason why it's important for me to have a plane that can go at 100kph or more, is that I may fly in wind that is up to 50kph, and want enough reserve power to fly against it back to the landing point. At Burning Man, I actually encountered a wind that peaked at 60kph right after a storm, while I almost lost my bixler2 as it was flying full throttle against a wind that was more than 50kph and was actually flying backwards (i.e. it was getting further and further away from me as its battery was draining while it was trying to fly back, and failing).
    Now, the next problem with the Sky Eye is that the plane wasn't designed for those speeds, and sure enough, after a light crash during flight testing, the wings got slightly bent, and the very little that was keeping them snapped into place, failed during a test run at 110kph+, the wings got ripped out in flight, and my plane had a very bad crash
    Thanks to my multiple radios and GPS coordinates, I did find the wreck, but I never found the wings, they were taken away by the wind at high altitude, and despite a 2H search around and downwind from the crash site, I never found them:


    i'm impressed the lipo did not blow up, it was a pretty high speed crash straight down (130kph)
    i'm impressed the lipo did not blow up, it was a pretty high speed crash straight down (130kph)

    To avoid this from ever happening again, I changed the wing design to allow a strap to go around the entire plane, including the wing roots. Sure, it makes the plane a bit more dirty to the air flow, but I'll take that for wings that won't fly off:

    made a hole in the wings, and added reinforcing wood
    made a hole in the wings, and added reinforcing wood

    with a velcro strap
    with a velcro strap

    initially I secured the wings like so, until I realized that in my crash the top part with the ESC broke off in flight
    initially I secured the wings like so, until I realized that in my crash the top part with the ESC broke off in flight

    so instead I'm wrapping around the body top...
    so instead I'm wrapping around the body top...

    to bottom, for extra strength
    to bottom, for extra strength

    With that fix made, the next sizeable modification I made was to allow the flaps to travel down a lot more for crow flaps. The only issue I found was that it wasn't suitable for landing, so I now release some amount of crow to avoid smack landings:

    I shaved off the flap hinge
    I shaved off the flap hinge

    allowing for severe flap down and better descent rates for a short field behind a fence
    allowing for severe flap down and better descent rates for a short field behind a fence

    Avionics and VTX

    For the avionics, while the cargo bay has a lot of room, but I opted for putting the pixhawk in a cramped and inconvenient space below the wings. The reason for this madness is to avoid electronics around the flight controller, and not have to worry about putting a battery on top or something else that would avoid free movement on top of the anti vibration foam pads. Cabling does suck as a result, but it really feels like the best place for it:


    As a result, I have plenty of room for the electronics and a big battery (4S 5000mAh, but bigger is possible). In there:

  • 3DR power module 90A
  • RCCCv2 3 channel video switcher plus switch for night lights and strobe
  • Battleswitch RC controlled relay to switch 12V for VTX and 5V for the 3 onboard cameras
  • Front Camera: mobius or GoPro Black 4K (both 5V)
  • Rear Camera: mobius with detachable lens
  • I2C Airspeed Sensor
  • MinimOSD with 5V mod, heatsink, and nightghost firmware
  • Brotronics Diversity RX with backup lipo and lost model finder buzzers
  • RC controlled buzzer to help finding aircraft in flight
  • 2W 5Ghz VTX in the tail
  • This is what it looks like:


    fit inside nicely, more easily than in the bigger BFG2600
    fit inside nicely, more easily than in the bigger BFG2600

    2W 5Ghz VTX gives 5 to 10km range in non ideal environments
    2W 5Ghz VTX gives 5 to 10km range in non ideal environments

    Sending the power and video to the tail in a prebuilt plane wasn't too hard, I just punched through 2-3 foam walls with this tool and pushed the cables through:


    nicely got to the other side
    nicely got to the other side

    all good
    all good

    Video

    Now, let's look at the video issue. Like other such blames, it comes with a plastic dome. Let's be honest, all those domes give very unsightly reflections from the sun while in flight. I didn't waste much time trying to fit a camera behind the dome, even if I did a quick test just to verify anyway:



    it fits, but as expected I got dome reflections on the video and didn't want that
    it fits, but as expected I got dome reflections on the video and didn't want that

    so I made a ghetto solution with foam padding that I carved. Looks like crap but better than an open hole acting as an airbrake
    so I made a ghetto solution with foam padding that I carved. Looks like crap but better than an open hole acting as an airbrake

    Now, the other way to do this if you don't need 4K, it's much easier with a mobius. Someone made a nice 3D model for a mobius dome that I was able to 3D print:


    it weighs the same as the transparent plastic dome
    it weighs the same as the transparent plastic dome


    I later printed this without the rear piece so that I could slide the mobius back, or change its angle more easily
    I later printed this without the rear piece so that I could slide the mobius back, or change its angle more easily

    not too bad
    not too bad

    I then also looked at other options for getting better than 1080p, and the Joovuu X almost gave me a 3K solution, but in the end the lens extension cable that took way too long to arrive, was too short, and also managed to short my camera and kill it:


    so I use a trusty 2K gopro with detachable lens in the rear
    so I use a trusty 2K gopro with detachable lens in the rear

    I also found an interesting mod for this plane, which was a 3D printed lock pin tail hook that allowed taking the tail off for transport. It was appealing in theory, but after trying it out on my broken plane (it required carving the tail surfaces that weren't big to start with), I concluded that it worked in theory, but there was no way I wanted to take the risk of flying loads with that setup and potentially lose the tail in flight due to weight and G load:



    this was the iffy part, lots of foam had to be removed, I didn't feel what was left would be strong enough
    this was the iffy part, lots of foam had to be removed, I didn't feel what was left would be strong enough

    Conclusion

    I like the Sky Eye, it's very reasonably priced ($150-ish), mostly pre-built even if I had to replace some bits and carve the flaps a bit, and the cargo space is fantastic, loads of room.
    I was dubious of the 8" rear prop at a weird angle, but it works well enough and I was able to get 800W out with an 8.5" prop and without a motor or prop adapter, so that worked fine for me. The only downsides are that you still have a whiny noise from the small prop and you're going to use more amps to fly against the wind, but I'll take that for a nice unobstructed few in the front.
    I think I only really wish it came with more custom made domes for popular cameras where the lens is in front, unobstructed by a dome.

    I'm very happy with the results I was able to get while overflying and filming burning man 2016 with 4K resolution.

    2016/08/01 Brotronics PowerTowerRX Documentation for Pin Mapping
    π 2016-08-01 00:00 in Rc
    After trying and documenting the Brotronics Broversity RX, I tried out a Brotronics PowerTower Rx. While the github page has schematics, sadly it does not even include a clear labelling of each pin, or the fact that output 5 seems not to be wired to a pin at all.

    You would buy the PowerTower Rx because you want a lipo backed up receiver which will sound an alarm on a loud buzzer (that you provide) once the signal is lost. It will also switch to transmitting a distress find me beacon after signal has been lost for 45 seconds, so you can use the radio signal to go find it, even if your main battery has been ripped out after a crash (happened in all my crashes).

    For more details on how that works, see my post on Brotronics Broversity RX, the missing manual.

    This receiver is more compact, cheaper, but does not have diversity RX, which is likely ok for most uses. But as I mentioned, it comes with 0 documentation, and not even a proper pin mapping. I ended up documenting this in this rcgroups post, but I thought I should make a proper page here with that info:


    There are 8 outputs in the RX configurator, but I believe only 7 are wired (#5 seems to be going nowhere?)
    If you use the buzzer for loss signal and loss model finder (you should) and don't solder to use RX/TX, you're really only left with 3 servo ports since #1 is used for PPM to your flight controller
    Port 2 can be connected to directly and 3 and 4 (RSSI and SCL) need to have a custom cable made because the layout did not include enough pins to just replicate Gnd/Vcc in the right places.

    Here are the channel outputs you can configure in the RX tab of the openlrsng configurator:

    1. PPM
    2. labelled SDA, can be analog
    3. labelled RSSI on board, can be sending different signal to lbeep pin if you solder a jumper
    4. labelled SCL, can be analog
    5. may not be wired anywhere
    6. link loss indicator (buzzer port, labelled BZ+ BZ-)
    7. RX
    8. TX

    The labelling on the board is pretty poor though. Here are the pins:

  • Pin1: PPM (port #1)
  • Pin2: Vcc (+ on the board is not aligned with it)
  • Pin3: Gnd (not labelled at all)
  • Pin4: Gnd (labelled -, off center a bit)
  • Pin5: RSSI (port #2)
  • Pin6: lbeep (I believe it's also port #2 and activated by a soldered jumper)
  • On the other side of the board, you have:

  • Pin1: Buzzer -
  • Pin2: Buzzer + => connect a buzzer to those 2 pins and set output port #6 to 'link loss'
  • Pin3: SCL is port #4, but you'll have to write your own servo cable with GND and VCC from other pins
  • Pin4: Gnd
  • Pin5: Vcc
  • Pin6: SDA => this allows to plug a servo cable between pins 4,5,6 to get Output Port #2
  • The wiring does allow to plug a servo cable directly into PPM on one side and Gnd/5V/SDA on the other side.
    This means you can connect to port #1 and port #2 directly with a servo cable.

  • Port #3 require that you route your own wires to make a servo cable out of pin 5 inthe back, Vcc and Gnd
  • Port #4 is the same with SCL, you have to make your own cable and route Vcc and Gnd
  • Port #5 does not seem to exist on the pins I could find
  • Port #6 is nicely wired with Bz- and Bz+, you just connect a 2 pin powered buzzer there
  • Ports 7-8 for RX/TX are on the other side of the board, you have to solder on them for some reason.
  • The battery port is also missing a header, but at least it has holes to add one. To be honest, I have no idea why anyone would buy this receiver if you're not going to use the battery backup. There are otherwise some cheaper or better wired ones you can buy (I did buy it for the battery backup which I think is a fantastic idea)

    2016/07/11 Bixler2 conversion to Pixfalcon with Micro HKPilot Telemetry Radio + OSD and Brotronics PowerTowerRX
    π 2016-07-11 00:00 in Rc
    In in herited a Bixler2 at the Baylands swap meet, and figured it would be a nice ardupilot/FPV test platform instead of that expensive and harder to fix BFG2600.
    I used the opportunity to try a smaller pixhawk: the pixfalcon, and a different Broversity OpenLRS receiver: Brotronics PowerTowerRX

    Pixfalcon Review for an RC plane: small but bad wiring

    Let's start with the pixfalcon and its accessories. I bought it to try it out because it was small. Long story short, it's a good value for size and money, but the wiring and plugs are really bad. Quite a shame :(


    I bought these 2:

  • PixFalcon Micro PX4 Autopilot plus Micro M8N GPS and Mega PBD Power Module
  • Micro HKPilot Telemetry Radio Module with On Screen Display (OSD) unit - 915MHz
  • It's a nice shrunk pixhawk. It offers almost all the pixhawk functionality but:

  • it's lacking the AUX1-5 outputs
  • speaker is internal. It works but it's not loud
  • the very worst thing about it are its connectors. The DF13 connectors on the pixhawk aren't big, so they should have worked, but the pixfalcon uses yet another smaller connector. This part really sucks because I have lots of DF13 cables and none of this new connector that really didn't need to exist. As a result I wasted time splicing cables because as soon as you want to connect to a regular pixhawk accessory, you need a hybrid cable with one type of plug on each side.
  • A somewhat worrying this is that my pixfalcon does not get powered by voltage on the servo rail. This means that it's only powered by its power module, making it single powered. This does not fill me with joy.
  • speaking about wasted time, the next problem is that the pixfalcon assumes that its 8 outputs are getting connected to ESCs for a multirotor. As a result, only the first one comes with VCC and GND, and the other ones do not, they only come with a single signal wire. Come on, now I had to waste more time adding the missing pins in the plugs and wire them all with VCC and GND so that I could plug them into normal servos. This is likely the most anoying thing in that kit, although it would also be the easiest one to fix.

  • the power module also feels inadequate if you're not using a multirotor. It's much bigger than it needs to be, but because of the non DF13 plug that needs to bring power to the pixfalcon, I ended up using it so that I could use the power cable with power plug. And the current sensor on it is pretty inaccurate below 3A, that's not good :(

  • Same problem for I2C: you have to make an adapter cable due to the use of different plugs. According to this post, the wiring order is also different: http://www.rcgroups.com/forums/showpost.php?p=34894771&postcount=469 but I have not found this to be the case when I made a cable for myself. Pixhawk wiring is here while pixfalcon wiring order is below:

  • speaking about those silly cables, they can also be too short. The GPS one was definitely too short and I had to splice 2 cables together to get enough length. Good thing the kit at least came with a spare
  • This then brings us to the Micro HKPilot Telemetry Radio Module with OSD. Another piece of hardware with 0 info, it wasn't quite clear if the serial port would be connected to the radio, or the OSD, or both. Turns out it's only connected to the OSD, so you use that to flash the OSD, and the radio, you connect to through the pixfalcon as a passthrough. I'm not sure if you can flash the radio that way, but at least I was able to configure it. All in all it's a cute little design, but I regret that the antenna is built on the board and that there is no connector for an external antenna. Range is probably 1km at best with a very good receiving antenna on your ground station.

  • I shrink wrapped it so that it doesn't short inside my plane
    I shrink wrapped it so that it doesn't short inside my plane

    Oh yeah, another problem with that very unfortunate use of those very small connectors is that the 6 pin cable that goes into the OSD board has wires that are too small and cannot carry enough current to bridge 5V from the video in to video out side. As a a result, I was feeding 5V from the video out side, and the voltage drop was too high and not able to power the cameras properly (like a couple of mobius, using 1A between the 2 of them combined). I had to dual wire 5V to be on both sides of the OSD board video port and ride on thicker wires.

    Brotronics PowerTowerRX review

    The Brotronics PowerTowerRX is a cheaper version of the Broversity module (without the diversity). It's actually not really smaller but it's a bit cheaper and offers 1S lipo backup to sound a find me buzzer and send a find me signal after a crash where your main battery got disconnected (actually that's very common):



    My review of the Brotronics PowerTowerRX:

  • lipo backup is a must. That's the main reason why I bought it
  • the labelling and documentation are again very lacking. I wrote some instructions here
  • Generally wiring isn't great due to lack of pins if you're hoping to get more than 1 PWM output (you have to double the ground and power pins and make your own 3 pin servo cables). You can get 2 more PWM outputs if you repurpose the RX/TX pins. One of the outputs (#5) doesn't seem to be wired at all on the board. Strangely the lipo pins are not soldered on the board, and I'd think it would be silly to use this board with backup lipo and then not have a buzzer connected so that you can find your aircraft after a crash and after the main battery has been disconnected.
  • So, this board is really meant for multirotors where you probably only ever care about PPM output, but it can be used as a slightly simpler board with backup lipo and crash buzzer if you don't want to spend more for the Brodiversity RX, and you don't mind the small wiring issues.

    Bixler2 (re)build and fixes

    I had a few things to fix on the airframe first, the ailerons and flaps weren't really tuned right, and didn't have enough throw. Also, I use differential flaps where 80% of the servo travel makes the flap go down (I'd use 100% but the foam cutout did not allow for this). This gives better results for crow flaps.

    the motor is enough to fly the plane with my extra gear, but not enough power to fly against heavy wind
    the motor is enough to fly the plane with my extra gear, but not enough power to fly against heavy wind

    As far as tuning is concerned, my BFG2600 needs elevator down on throttle up, otherwise the plane pitches up too much on full power, all the way to a stall. Interestingly on this plane it pitches down a lot on full power, so I have to give it a lot of elevator up on throttle up. My CG is also off (too much weight in the front with the 2 cameras), so I have a fair amount of nose up trim for level flight.

    Speaking of cameras, I started with a JooVuu X for 3K video (better than the 2K from a mobius) I wanted to try out, but unfortunately it's pretty big compared to a mobius, and it does not support detachable lens yet. Also I don't yet have the analog out cable for FPV, so I had to add a 2nd analog camera:


    The end result is a plane that is pretty packed, and it's definitely a challenge to avoid interference between the multiple radios, but I think I managed:


    But this was a quick hack, this top FPV had much of its view blocked, making it hard to see the ground or if I was heading towards a tree. I ended up using a mobius with detachable lens and put the lens all the way in the front nose, for a great view, but the 2 cameras combined do upset the CG a fair amount:

    mobius is leaky and damages RF signals, so I made a small faraday cage for it
    mobius is leaky and damages RF signals, so I made a small faraday cage for it

    So I can put it in the canope without it messing with the radios around it
    So I can put it in the canope without it messing with the radios around it

    this is how it looks: front lens from mobius inside, and JooVuu X on top
    this is how it looks: front lens from mobius inside, and JooVuu X on top

    The 25A turningy ESC that came with the plane was utter crap. Its 2A BEC was overheating and likely to fail quickly, so I replaced it with a BEC, but the 2 combined were a bit big and I was able to replace them with a nice Castle Talon 25 with up to 8A capacity on the BEC (sadly the Talon outputs 5.5V instead of 5V, which the mobius doesn't quite like):


    All in all, I like the plane, but the stock motor while frugal in power (10A at full power on 3S) does give a generous 25mn of flight at full throttle, doesn't fly faster than 50kph or so, which caused me to almost lose the plane when I was in very heavy wind that prevented it from flying back:

    2015/12/23 Fatshark Goggles That Don't Fit You Cannot be Returned. This sucks for a $520 Fatshark Dominator HD v2
    π 2015-12-23 00:00 in Rc
    This is a warning to others. I was tricked by the review youtube videos from Team Legit saying that the new dominators (HD v2 and Dominator v3) leading me to believe that they were best thing since sliced bread, and got a pair of each to see which one would fit me best, as a backup/alternate for my current collection:
  • Skyzone v1 (head tracking, diversity receiver)
  • Skyzone v2 (head tracking, diversity receiver, 3D, recording on internal SD)
  • Headplay (huge screen, built in receiver)
  • First, let's remind everyone that fatshark goggles:

  • Are noticeably more expensive than other goggles and whether they'e better is debatable
  • Fatshark does not include a head tracker module, or even a basic 5.8Ghz receiver. Those cost extra, making the goggles even more expensive
  • There is no option for a diversity receiver like the skyzones (and it's awesome to have circular + helical on skyzone)
  • The fatshark dominator v3 are no better than the skyzones unless you can use HDMI in at 720p. Otherwise, I don't really see a good reason to buy them. The Dominator HDv2 have a huge screen/field of view, they do, but it's impossible for me to see it all due to insufficient IPD adjustment, and the sides of the screen are still blurry for me (unacceptable for a $520 goggle that doesn't even include a receiver or head tracker).

    For me, they are overhyped expensive goggles that sell without a receiver but for more than their competition that includes 5Ghz receivers, but more importantly if they don't fit you, FS doesn't give a hoot. After buying a $520 fatshark HD v2, having to glue on some foam insert, or you can't even try them/wear them, and realizing their IPD is all wrong and I can't see the sides of the screen (and when I can, they are blurry), getfpv told me they could not refund me for them because fatshark would not take them back.
    Needless to say that I'm not impressed with a company that refuses the returns of products used once and that they couldn't even design to work properly on wider western faces. The black foam insert on this picture actually needs to be glued on the goggles to really be able to try them on, and the moment you do that, they are not returnable.

    Details: My face is a bit wide, so I have to use max IPD on all goggles, and even then the distance between my pupils always seems to be a bit more than the goggles, so Im not seeing the sides easily, or at all.
    The skyzone goggles are a great buy with their diversity receiver built in, but using them is not super comfortable for me due to the IPD problem.
    The skyzone 3D V2 goggles have one extra mm in the max IPD, so they're almost ok for me.

    Yet, I figured I'd try the newer fatsharks since they are supposed to have a great IPD. After seeing reviews that the HD Dominator v2 had the biggest visible screen in the market (not counting headplay), and that they were worth the money, I thought I'd give them a shot along with their cheaper cousin, the Dominator v3. Well, sure enough they didn't fit me: I couldn't see the whole screen on the HD v2, and the sides were blurry on top of that. Needless to say that I find it unacceptable that fatshark will not authorize returns of goggles that do not fit. I, for sure, will never buy anything from fatshark again. While I wish getfpv could have processed a return without charging me 20% restocking fee, they assured me that it was really only because that's the cost they incur from fatshark themselves who does not allow returns of used products, even if they didn't fit.

    For my remaining options, while the fit isn't perfect, I'm pretty happy with my skyzones v2 3D, incredible bang for the buck (and the receivers work quite well, I got more than 7km out of them). The fatshark dominator v3 also fit me ok enough, but don't even come with an RX receiver which costs extra and isn't a diversity receiver like the skyzones, nor do they support real 3D with 2 streams, again like the skyzones do (but skyzone v1 does not have built in recording, only skyzone v2 does).

    Hope this helps and I hope fatshark changes their policies, because their current one sucks.
    To be fair, maybe other goggles are hard to return too, but at least you can use them while keeping them 100% pristine, and being abel to return them at minimal cost if somehow they don't fit you.

    2015/12/20 Hacking MinimOSD-Extras to do what I needed thanks to OSS: Mode Rotation with Channel Toggle
    π 2015-12-20 00:00 in Rc
    MinimOSD-Extra is the open source arduino software that takes mavlink data from ardupilot and creates an on screen display on top of your real time video to give you a clue where you are, which direction you should go to fly back to home, how much battery you have left, altitude, airspeed, and artificial horizon if you're flying IFR, at night, or your camera being displayed (I have 3, one rear facing) does not give you a proper horizon you can refer to for hand flying.

    Sadly, the device it runs on only has a measly 32KB of flash space, and with all the code it needs to interface with mavlink/ardupilot, talk to a video chip, and do calculations before displaying the result, you can't add much of anything to the current codebase. For reasons that I do not understand, I have not found anyone making an OSD board that would be compatible with the current code while providing more storage for new code.

    While I'm not a big fan of the closed source commercial Vector flight controller, it has a really good OSD compared to ardupilot and minimosd. In the meantime, though, I needed minimOSD to be able to rotate my OSD screens without burning an extra switch on my transmitter. I need to rotate screens because I'm doing 3D FPV flying and it's distracting to have OSD data in one eye when you're trying to get a 3D effect from 2 images :)

    The way you can do this without burning an extra RC channel is to use rotation swiching on an existing channel (you can also use rotation switching on the APM mode switch, but that never worked reliably for me), but the released code rotates forever as long as your switch is not in the down position, making the switch not usable for anything else.

    Thankfully it's open source, so I was able to take the arduino code and improve it to do what I needed. Now, with my custom branch I can rotate the OSD screen by simply flipping any selected switch to any position and then back. This works with the mode switch too if you'd like (sadly the channel number is hardcoded to only be 5 to 8).
    You can get my version from https://github.com/marcmerlin/MinimOSD-Extra (only compiled for plane, but you could port the code to copter if you wish). I've also cleaned up all the compilation warnings in the code, and removed a bit of dead code I found.

    Pre-built binaries for plane: https://github.com/marcmerlin/MinimOSD-Extra/tree/master/Released/FW%20%26%20Char

    Here are some screenshots from my OSD configuration:

    60 degree pitch up, 82% power, 41A, 533W used
    60 degree pitch up, 82% power, 41A, 533W used

    stall speed 27kph under near full throttle
    stall speed 27kph under near full throttle

    The OSD horizon comes in handy when switching from the FPV camera to the bottom and rear facing cameras:

    FPV cam
    FPV cam

    bottom cam
    bottom cam

    rear cam
    rear cam

    OSD flipping:

    OSD screen #2
    OSD screen #2

    OSD screen off to allow for a proper 3D view
    OSD screen off to allow for a proper 3D view

    This is also useful for debugging and filing bugs. Guided mode was supposed to take over at 70m (it did), and fly back up (it did not, it pitched down, went up to 80pkh while pitching down and losing altitude down to 26m before I took over for manual flight):


    2015/12/18 Compilation of FPV flights around the Google Mountain View Campus
    π 2015-12-18 00:00 in Rc
    More than 5 years ago, I took a video of the Google Campus from my Multiplex Cularis with a Gopro hanging from it, flown visually from the ground. While the footage was great for the time (click for my old video from then), I only did it once because it was very challenging to fly that far from my takeoff point with unaided view, no auto pilot to recover in case I lost track, and no telemetry on my battery status. I landed with very battery left at the time, even if my plane was capable of gliding a fair distance without motor power.

    In 5 years, many things changed in the campus, it got so much bigger, and I wanted to be able to get other buildings that I wasn't able to reach safely. I was however not comfortable enough doing this while piloting with just a ground view and without safety info like real time battery status, winds, and so forth. This is why I waited that long until I had a new plane setup for FPV (first person view) with an OSD (heads up display equivalent) that could give me real time flight information, including winds, motor power, altitude, glide ratio and battery remaining.

    lots of electronics involved
    lots of electronics involved


    FPV ends up being safer due to how much information you have when flying, better than many full size private planes
    FPV ends up being safer due to how much information you have when flying, better than many full size private planes

    If you are curious about the plane itself, a BFG 2600 with pixhawk, 800W motor, 4000-5000mAh 4S lipo, 2 mobius cameras, 2 top FPV cameras for optional 3D flying, , 433Mhz dual path frequency hopping openlrs receiver with back channel for telemetry (good for 20-30 km range), 600 to 2000mW 5.8Ghz video (good for at least 7km range), and 900Mhz control and telemetry backup channel. This is absolutely overkill for those kinds of short range flights, but when safety is involved, overkill is good :) You can read more about it here.

    The next problem were the 2 airports within range, Moffett and Palo Alto. Moffett was not much of a problem since it has very little traffic and was not in the way, Palo Alto however is located so that landing planes can fly over Google. This was solved by checking with the airport and having an airnav radio to listen on tower frequency for landing airplanes to help a spotter look for traffic. The other thing was to keep the altitude as low as possible so as to be below altitudes airplanes could reasonably be expected to be. However in theory, landing airplanes could fly below 400ft, so using a spotter was helpful.
    Also, for safety of flight of the RC plane, it was also desireable in places to have a bit of altitude in the bank so as to be able to fly to a safe landing spot as opposed to crashing on a road or over people in case of a motor failure (flying times and locations were chosen so as to minimize people and cars). The plane itself if a 2.6 meter foam glider, so it is able to glide quite a distance without motor power.

    The RC plane itself is flying with ardupilot, a very capable auto pilot that computes winds real time, gliding distance if the motor isn't running, real time battery used and remaining, and most importantly was programmed with a minimum altitude deck to take over from the pilot, recover from a bad flight condition and fly back to the landing spot on its own if the pilot were to lose video or control ability, or just to get confused and make a mistake (if you wonder, for landing the pilot turns this off, or the airplane would not come down low enough to land). The last safety aspect was the fact that the plane was more than 95% compressible foam with a plastic propeller that folds back when not in use. This means that in case of failure and impact, it does not fall nearly as fast as a quadcopter, and it absorbs most of the Gs on impact by destroying itself while causing very minimal to no damage to something that could be hit, should it not be the ground. A quadcopter would be absolutely unsafe to fly over people and cars at any time due to the amount of damage and injury or worse, it can cause in case of impact.

    While this may look easy, I want to stress that it wasn't. The pilots had more than 10 years flying RC and/or full size planes and were extremely mindful of safety. While I'm happy to share this with you, I want be clear that this is not an invitation to emulate those flights with an RC aircraft you just bought, and definitely not with a multi rotor/quadcopter aka drone, as the non toy sized ones are just not safe to fly over people. Foam RC planes are extremely unlikely to cause real injury to people in case of impact, while multi rotors of a certain size can unfortunately kill someone if they fall straight down on their head from a certain altitude. I refer you to this page for a longer discussion about the safety aspects
    However, in a nutshell: flying, airspace, and safety can be quite complex, so I don't entirely blame the FAA for not trusting the average RC pilot without proper training on all 3 (even if said RC pilot is very capable at flying an RC aircraft, which is not true of all), and trying to put over restrictive rules as a result. Still, I hope they can work with the AMA to come up with more reasonable restrictions even if the current ones still aren't legally binding yet (outside of registration of pilots or aircraft), and ideally come up with a class of RC pilots who has acquired additional airspace and safety knowledge, and would be bound to less restrictive rules.

    The pictures and videos below were made from clips taken from a few flights over a 6 month period of time in 2015. Flights were flown by different people, at times I was the spotter on the ground and safety backup pilot. The pictures are not in chronological order, and the 4 video mashups (one per area), are made out of clips pasted out of order.

    The 4 videos are here, these have music. The 4 copies below in each category, are with original RC sounds (click on the link to get the 1920x1080p version on youtube):

  • Google Main Campus: https://youtu.be/XW_LKMyLzwo (it has (too) many angles, it's ok to fast forward)
  • Other Google buildings nearby, and Google West Campus: https://youtu.be/-4hQU4EDVms
  • Crittenden Campus: https://youtu.be/ZeAGuZMTw-I
  • Nearby Shoreline Amphitheatre, Golf Links and Bay Marshlands, Intuit Buildings: https://youtu.be/XMuczi-URso

  • Here are now pictures and videos for the 4 areas flown:

    Google Main Campus

    The soccer field across and other sports fields. Video summary (with RC sounds, choose the video in the list of 4 above to get the version with music):

    Screenshots:








    It's right across from 1950 Alsa:













    Nextdoor is the so called main campus, B40-43:
















    Google West Campus and Other Surrounding Buildings

    Across the street, B44, and ACI which I didn't know had their name on their roof. Maybe if someone comes to bomb Google, they want to be spared :)
    Video summary (with RC sounds, choose the video in the list of 4 above to get the version with music):

    Screenshots:




    B45, B46, B47:






    1098 and 900 Alta:



    Moving to Landings and Google West Campus (formerly 0, 1, E, and Pi):








    Google Crittenden Campus

    Across shoreline, is the Crittenden Campus and other tenants on Stierlin Ct.
    Video summary (with RC sounds, choose the video in the list of 4 above to get the version with music):

    Screenshots:







    pretty full parking lot
    pretty full parking lot






    Moffett Airport is just next door, so while it was possible to get one shot of it without entering their land, it had to be done carefully (while the runway wasn't active, even if the RC plane never got close to its extended centerline, a very bad idea no matter what)
    Moffett Airport is just next door, so while it was possible to get one shot of it without entering their land, it had to be done carefully (while the runway wasn't active, even if the RC plane never got close to its extended centerline, a very bad idea no matter what)

    Nearby Shoreline Amphitheatre, Golf Links and Bay Marshlands, Intuit Buildings

    Last, but not least, here are some shots the the bay surroundings, again some had to be taken carefully so as not to conflict with airplane traffic going in and out of Palo Alto airport (using a spotter and being on tower frequency)
    Video summary (with RC sounds, choose the video in the list of 4 above to get the version with music):

    Screenshots:





    Pictures of Shoreline Amphitheater:








    Intuit Campus:






    Michael's at Shoreline by Golf Links. Where my friend Grant had his birthday :)



    2015/12/13 Eagle Tree Vector vs Pixhawk/Ardupilot
    π 2015-12-13 00:00 in Rc
    This was written in december 2015 with the latest firmware available at the time.

    I worked with a Vectone on an hexacopter, and honestly I was very not impressed with it.

    On one side, it looks polished, it's nice to have the OSD built in the flight controller.
    There is a nice professional manual (vs ardupilot where the docs are ok, but just not as polished).
    However, as far as doing its main job of being a flight controller for the hexacopter, it sucked.

    Once, only once did I get to run the level function and did it fly the copter level.
    All other times, I had to put various amounts of trim (sometimes so much trim that it would not arm without all that rim), and once you give it all that trim, if you do a 360 rotation, it tends to wobble or tumble depending on how much trim you have.

    I can't say how many times Eric and I levelled it (and it was really level), but either way an imperfect level is not an excuse. The copter can see in flight that it's pitched and moving in one direction without corresponding RC input, and cancel that out. It sure does not.

    It randomly (50% of the time) failed to work in altitude hold mode. Loiter (GPS hold) never worked despite GPS signal. Compass had been configured (and that was a pain), and during the flights, the OSD said it has to be configured again (and this was the latest firmware)

    In the meantime: Arducopter has autotune. I can't say how awesome autotune is to auto-set pids for a given airframe.
    Vector does not.

    Arducopter has EKF to double calculate everything using all available sensors.
    Vector does not, and sucks as an hexacopter flight controller in my experience (and Eric had the same problems as I did, even after fully reconfiguring the flight controller).

    Arducopter/pixhawk uses 2 compasses (one in the FC, one external).
    Vector does not.

    Pixhawk supports 14 inputs and outputs.
    Vector supports 6 channels (so you need to have other channels available as PWM on your receiver, which may not be possible if you want 14 or 16 total).

    Vector cannot be configured via computer while in flight, or while armed and requires wireless video for remote configuration (not great if you don't have an FPV screen).
    Ardupilot uses a wireless radio/serial connection and can be fully configured/monitored while armed or in flight.

    While I liked the polish and wiring of the vector, the fact that it is clearly inferior as a flight controller for hexacopters at least, makes it a poor choice in my opinion.

    Too bad. I kind of wanted to like it, especially because its OSD is far superior from minimOSD on ardupilot.

    2015/12/12 Hexacopter flying at Moffett
    π 2015-12-12 00:00 in Rc
    I went to Moffett to help with data collection of hangars from the inside. Got a few nice shots while there, we even got a couple of F18s that took off for us:









    We then went to the next hangar, with big doors we got to open :)








    See more images for Hexacopter flying at Moffett
    2015/12/01 Flying 3D FPV with Skyzone 3D FPV Goggles
    π 2015-12-01 00:00 in Rc
    This is my review of the Skyzone SKY02 V3 AIO 3D FPV Goggles, which I got to supplement my Skyzone Dual Antenna FPV Goggle V2:

    I had the old Skyzone 2D goggles with dual receivers and diversity controller, and I quite like them. However, they are sadly made for smaller faces than mine, and even by putting the lenses as far away as possible, it's barely wide enough and I have to strain a bit to see the whole screen. Bummer.

    Summary of Skyzone 2D vs 3D:

  • 3D has 3D (obviously), but with each receiver getting a separate full resolution image (vs fatshark and others that do SBS, i.e. half resolution)
  • Both have the same diversity controller (two receivers, two antennas), and in 3D mode you change diversity for 2 separate receivers. Range of the receivers seemed equivalent in my side by side real world flying test (some reviews said the early versions of the 3D had a bad receiver, mine did not)
  • Nice OSD menus in the 3D (not present in the 2D)
  • Support for recording to microsd card (sadly 2D recording only, I'd have loved 3D recording)
  • As a minus, in PAL, the 3D goggles crop a little bit of the bottom of the picture, I had to move my OSD text up one line (not an issue in NTSC)
  • The IPD is slightly better (see below) for my eyes
  • The 3D comes with a dual VTX and a dual camera (the 2D comes is goggles only). To be honest, I'd have loved to buy the 3D goggles only.
  • The skyzone 3D goggles sadly don't offer much more IPD (interpupillary distance), but the extra 1mm helps a bit and wearing them is a bit better for me than wearing the 2D goggles.
    I have just now tried some fatshark Dominator HDv2 and dominator v3s, and both also make it impossible to see the whole screens from left to right with both eyes on max IPD setting. That's disappointing, but basically means that the IPD on the skyzone 3Ds isn't really much worse for my face. In real life each of my 2 eyes misses a small part of the side of the screen, and the other eye makes up for it, so it's not too bad.

    I was however worried when I saw reviews that were saying that the receivers on the new skyzones, were of poor quality and range. Without knowing for sure, I ordered them and went to test them. To my relief, they gave me the same 5km flying distance I was getting with the original 2D skyzones. In other words, the skyzones 3D are just a positive upgrade from the 2D ones.

    Next, was trying 3D. Most people seem to have tried them on quadcopters to fly between trees at close range. That's all nice and good but my application was a plane, and not flying that close to objects. I was also not very impressed by how heavy and bulky the default camera was, as well as the dual VTX. At the same time, I didn't have high hopes of the dual VTX being any good for long range, having 2 transmitters that close to one another cannot be good. So, I ended up using 2 regular VTXes, with more room between them, and reverse polarized circular polarized antennas.

    This is what the default setup looks like:

    So, this is what I did: I made my own 3D camera, one with the proper IPD (the skyzone cameras are too close), and one with a very elongated point of view, almost like a hammerhead shark. It helps seeing 3D effects at longer distances (more than you would see with normal vision).

    I used the stock camera (but not VTX) for my first test. It was very disappointing because the camera could see the plane, and that ruined the 3D effect. Also, as expected the 3D perception wasn't going to work well with the cameras so close to one another:


    So I made my own 3D camera:



    narrow
    narrow

    wide
    wide

    install before flying
    install before flying

    2 video transmitters, 600mW with LHCP antenna, and 2W with RHCP in the back
    2 video transmitters, 600mW with LHCP antenna, and 2W with RHCP in the back

    I've only done one test flight with that setup, but having the cameras be far apart works great for seeing 3D at a longer distance, and also I'm not seeing the plane, which is good. The only issue is that my servo doesn't have enough torque to deal with that much weight, so when I have the wide camera setup installed, I just unplug the rotation servo.
    Using the 2 VTX with some distance between them, and RHCP + LHCP gave good results, I was able to fly 5km away without problems.

    All in all, it's a pretty cool system, even if I don't like their cameras or the bundled dual transmitter (they should sell the goggles alone for people like me), it's a very cool setup. Now please just make one for faces that are wider and allow more IPD like fatshark does.

    The most unfortunate thing is that the goggles cannot record 3D, they only record one eye in 2D. To get 3D, I'd have to use 2 sets of goggles, each to record one channel, and then synchronize the recordings and make some SBS video out of it. Sounds like a lot work...

    Update:
    Actually, since I realized that I cannot turn my dual camera setup anymore, I went ahead and put the cameras even farther apart: in the wings. They are a bit hard to line up, but they do give a better 3D effect at even greater distances now:

    I have about 1m between the cameras, and should try to move them even farther apart
    I have about 1m between the cameras, and should try to move them even farther apart


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