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Thread: X-UAV Clouds 1880mm FPV plane - full review / build log / mods

  1. #71
    Navigator Arxangel's Avatar
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    UPDATE 6 - FrSky R9M module and R9 receiver testing

    And its time for yet another update of this fine plane! As some of you already probably know, I recently got the FrSky R9M module and R9 receiver, which are FrSky's new long range system operating on 868Mhz for Europe, and 900Mhz for the rest of the world, and which one you use is deterimined by the firmware you chose to install. Along with the set I also got the R9 Slim, but that went on a new custom copter I am building with 6" props... will try to do some cloud chasing with it... lets see if it is possible!





    After quickly weighting my options, I figured the Clouds was my best bet when it comes to reliability, because it has returned on its own from 22kms out during my L9R receiver testing, and I knew its RTH was working correctly, so no matter how the R9 performed, if it lost signal, the plane would come back without too much issue.





    However, the R9 needed a slight modification, if I was to utilise all of its functions and be able to monitor RSSI. The L9R, lacking telemetry and all, did have the RSSI output to a pin, and it was easy to wire it up to the autopilot, so I can see it on my OSD. Since the R9 receiver is telemetry capable, and because it also has redundancy, meaning you can connect another receiver's SBUS output to it to act as a backup signal, it was lacking the RSSI pin, mainly because FrSky use the same PCB layout and case for most of their big receivers now... and I guess they weren't going to change the whole design for that! So they provided the P4 pad on the PCB, where you can solder a wire, and then connect it to whatever will be monitoring the RSSI, just like you would with any other receiver! As far as I can tell, the output of the pad is analog, NOT PWM!








    In order to take the wire out of the casing, I drilled a small hole directly above the pad.





    The other end of the wire got a connector directly compatible with my current wiring on the Clouds.





    Swapping the receivers was super easy as they mostly have the same ports and are of the same size!





    Only remaining problem were the 900Mhz antennas, and I got the model with the thin and flat antennas. Saying that they were not a good fit in the existing L9R antenna mount would be an understatement! They were so soft and bendy, that even taping them there would mean they would get warped in flight because of the air going around them!





    So... the solution was to print out some antenna braces, which would enable me to mount them securely in the existing antenna mount, and also would allow me to mount them the same way as the L9R antennas were mounted, hopefully giving me the same outstanding results! I held the antennas in place with heat shrink, and there is actually another reason why going to the 868Mhz firmware might require you to put some dielectric on the antenna, even if you don't need to reinforce it to make it stiffer! Since the stock antennas are tuned for the 900Mhz frequency... using them as they are on 868Mhz might not be the most optimal solution. I haven't measured them, but from my work on 5.8Ghz antennas, I know that adding plastic bits or heat shrink around them lowers the resonant frequency, so my hope is that the printed braces and the heat shrink do enough do bring that frequency down closer to 868Mhz levels!











    The connectors from the receiver are also pretty good! They rotate freely... but I was not able to easily remove them!





    The R9 looks a bit funky with that RSSI wire coming out of the casing like this, but at least I got my DIY moment here!











    They look pretty good once beefed up and mounted in the holder! I sense great potential here!





    As for the R9M module, it looks pretty much identical to the XJT module, just with different stickers.









  2. #72
    Navigator Arxangel's Avatar
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    Fits perfectly at the back of the Taranis, unlike the iRangeX module I have, which fits OK as you insert it, but it is a pain to get it out!





    Alright, so having survived the trip to the out-of-city airfield, where I like to do my long range flights for the most part, it was time to take this one up and see what this 868Mhz long range system is capable of!








    A lot of people have asked me why I have mounted the antennas in this way, why not put one of them horizontal, etc., FrSky supposedly suggested the proper way to mount these, and so on, but let me tell you something... FrSky advertise the L9R with a max range of 3kms, whereas I got it to 22kms without loosing link, by mounting the antennas this way... so yeah... I'd rely on my personal experience to be more accurate than some technician's assumption based on a software calculation of antenna signal propagation!! They were pretty surprised with my results when I told them! I can only assume and hope, that I will observe the same behaviour here as well!


    Here is the thing about long range and antenna mounting - the antennas need to be mounted according to the application! Mounting one antenna vertical and one horizontal, or both at 45 degrees to the ground plane, and 90 degrees to each other is all good and dandy, but only when flying aerobatics, 3D, etc., where the plane is close to you, but moving all over the place, so you need to make sure you get a good signal even when doing a knife edge, or a loop, or a roll! On the other hand, at least for me, long range is completely VOID of such manoeuvres. The last thing I want to be doing at 25kms out would be to start banking at 40 degrees, doing sharp turns, or aerobatics! You will see in the video below how slow and gentle is the turn I made to head home, trying to bank the plane as little as possible, and thus maintain best polarization between the antennas on the plane and the one the ground. Furthermore, when I have a receiver with flat antennas, like is the case here, I always assume one of the sides, either the thin, or wide bit, is more directional than the other, hence why I rotate the antennas 90 degrees to each other when mounting them, to make sure that no matter which way the plane turns (YAWs), one of the antennas will have its more sensitive side facing me! Antennas at an angle just don't make sense for me, when it comes to long range flights. Anyway, that is just my personal opinion based on a lot of experience, feel free to ignore it and prove me wrong!





    As usual, the Clouds requires very little preparation to get going.








    With my new favourite FireFly 8S camera mounted on the gimbal, it was time to see what this R9 receiver can do with the Feb 2018 EU LBT firmware, at the 500mW power output option.





    Here is the video, I hope people find it useful!







    That certainly was some impressive performance out of the R9 receiver - 25kms with 80% RSSI remaining! I was actually more impressed by the video quality at that distance... it was still flyable!!


    A few days later, I decided to realise another flight that I've been wanting to do since last winter, and that is to fly from our in-city flying field out to the top of the nearby mountain, while there is still snow up there! Since there is an aircraft radar up there, that would also give me a chance to see how the R9 will perform close to it... just out of curiosity!





    The goal is to fly lower above the terrain as I am climbing the mountain, which should give me some nice and detailed shots of the ground below, not like with the usual high altitude flights, where I would get well above the peak before I actually got there!





    Nothing was changed on the plane from the previous flight.





    Everything is ready to go! Sometimes it is so easy when I have only 1 plane to fly... have to love simplicity!





    And here are the results of this test:





    This is all for now guys. Next on my list for Clouds testing is the new AKK X2 Ultimate video transmitter, which has an insane 1200mW output option... in the same 6 grams of weight as the AKK X1P I have on the plane right now! Stay tuned for that long range test!

  3. #73
    Navigator Arxangel's Avatar
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    UPDATE 6 - AKK X2 Ultimate Vtx 1200mW long range test

    OK, an exciting update today, as I will be testing the new AKK X2 Ultimate video transmitter, capable of up to 1200mW of power output (antenna in the photo does not come with it). I got two, so I can verify my temperature tests, and also so I can have a spare for installation in a second plane, if I feel the need.





    In this photo it is next to the AKK X1P, which was in the X-UAV Clouds up until now, but it is only capable of 600mW max output. As you can see, the only thing bigger with the X2 Ultimate is the PCB. The transmitting module itself seems to be about the same size.





    Both Vtx units are very similar. Only differences include an MMCX to SMA cable on the X2, vs just a right angle SMA soldered to the X1P, X2 also has 1 more pin on the connector, and a microphone, which the X1P lacks.





    Wight wise, the X2 Ultimate is a bit lighter than the X1P, but the latter does have the heat sink on it... so I'd say they should be about the same weight, when you include the cables. If you can get the antenna you want with an MMCX connector, then the X2 Ultimate should be a tad lighter.








    This is how I had mounted the X1P on the Clouds up until now, and since this mount is glued in... I will have to make the X2 Ultimate fit on this.





    Sadly, I can't use the X1P's connector, since it has 1 less pin, and these connectors just don't fit if they are not an exact match.





    Not a big problem though, un-pinned the connector, so I can put an X2 compatible one in its place. At least they are of the same model.





    Shortly after, all was good. Not going to be using the Smart Audio option, as I don't think that is possible on a non-Betaflight autopilot.





    My indoor temperature tests on both X2 Ultimate units I got revealed that they both heated up to 90 degrees C within 3 mins of being plugged in at the highest power setting of 1200mW. I decided to add a heat sink to one, before mounting it on the plane, so I can extend that time a bit. It worked well for the X1P, and I hope it will do the same here.








    A short while and some thermal paste later the deed was done.





    The temperature test that followed revealed that it now took 5 mins at 1200mW for it to reach 90 degrees, which is good. Should give me plenty of time for GPS lock and other preparations before takeoff. Once it is in the air, it should cool down and overheating should not be an issue!





    I decided to mount the X2 Ultimate a bit higher on the mount pole, so I can install the SMA connector in the existing hole, and have the Pagoda antenna mounted the same way as before, as having it straight up could alter the results, and I wanted to keep as much as possible the same as last time, to give both tests an equal footing and try to narrow the difference in range down to power output only!





    And now for the test... the day was very similar in weather and temperature to the one before when I did the 25km flight. I used the same antennas on the antenna tracker, mounted in the same way, the same antenna on the plane, was at the same location and flew in the same direction, gaining the same amount of altitude! I am impressed by what this Vtx showed, but a slight misjudgement on my part left the distance shorter than it could have been, so will remedy that as soon as possible and will go at it again very soon!


    In the meantime, here is the test now, I hope you enjoy it!



  4. #74
    Do you happen to have a method to verify output power, something like an RF Explorer? I've tested a few of these small transmitters (never used AKK though) and found power outputs all over the place, even wide variety when selecting different channels or bands on the same VTx. Occasionally I'll find one that is a little higher than advertised, but usually I see a few dB less to nearly half of rated output.

  5. #75
    Navigator Arxangel's Avatar
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    Quote Originally Posted by Fyathyrio View Post
    Do you happen to have a method to verify output power, something like an RF Explorer? I've tested a few of these small transmitters (never used AKK though) and found power outputs all over the place, even wide variety when selecting different channels or bands on the same VTx. Occasionally I'll find one that is a little higher than advertised, but usually I see a few dB less to nearly half of rated output.
    I don't have the RF Explorer thingy, but a friend of mine does have it, and we might do some measurements, but if what you say is true... then it could stand to reason that the 600mW Vtx is not really 600mW, but 500mW. And then if we assume the 1200mW Vtx is actually 900mW or 1000mW... you still end up with the same "twice as powerful" situation... so the test should still be valid!

  6. #76
    Navigator Arxangel's Avatar
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    Hey guys, here is a short video about my ground station, so you can get an idea of the ground side of things behind my recent long range flights.



  7. #77
    Navigator Arxangel's Avatar
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    Alright guys, here is something very recent with the Clouds!


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