Servers by jDrones

Beginner building TurboBeaver / Your input is welcome!

Hello everyone,

As this is my first post, hello to everyone !

I’m about to start learning and building a TurboBeaver with Pixhawk 2.1 and Cube Orange ( with ADS-B Carrier Board ). As I’m in the planning phase right now, your input is highly appreciated to avoid unnecessary problems early on.

I want to begin with showing you what I’ve got so far and what I wanna build with :

  • Black Horse Turbo Beaver
  • Pixhawk 2.1 / Cube Orange / ADS-B Carrier Board
  • Here 2 GNSS Module
  • basic 6s drive train
  • TBS Core Pro FPV System (5.8 ghz, Blackpearl GroundStation, TBS59 Cam(s) )
  • Not sure about the servos yet
  • Spektrum DX9 tx

I’ve been reading a lot so far and watched many Painless360 videos on how to basic setup the flight controller. I hope this will get me started well, if theres something I should be aware of in addition to that, please let me know. I plan to have the flaps of the plane in a fixed position to save a radio channel. I use a Spektrum DX9 (unmodified) and will connect to the flight controller with the Spektrum Sat port.

My first goal is to just make the plane fly properly with the Flight Controller, utilize the auto trim and have everything going smooth and just working as expected.

Yet some questions are still bothering me right now, I hope you can answer them for me :slight_smile: :

  1. I want to have a FPV cam mounted below the plane next to a GoPro, so that I can see what I’m recording right now. These 2 cams should sit on a pan-tilt module, utilizing 2 servos. I want to control these 2 servos with the Rknob and the Lknob of the transmitter. Setting that up should be easy. Ideally, the plane should be in loiter mode, circling an object, while I just control the pan tilt so that I manually focus on whatever I want to record. I read that during the loiter, the flight controller is in auto mode and I cant control anything then. Can I set up the flight controller, so that the plane is in loiter and I can still manually control the pan tilt ?

  2. As I fly Spektrum and can only connect via the Sat Port to the Pix, it is likely that during an Auto Mission in future the plane will fly out of range of the radio. Will the flight controller continue the mission or do something else ? How do I setup the failsafe in the radio, so that the mission wont end in a disaster ?

  3. Im limited on channels to switch the flight mode, to get another channel free I can build the plane so that the flaps are fixed. Is it necessary to fly with 6 flight modes or can I just set them up to Manual, Loiter, Auto and it all will work fine ? If no, I´ll as mentioned just have the flaps fixed mechanically in neutral position.

  4. The plane itself is very basic. 2ail, 2ele, 1 rud, 1motor, (2flp). The FPV System ist very easy to setup as well as its not connected to the flight controller. Where do you see major problems I may run into and how can I avoid them beforehand ?

  5. This question is regarding the connection Ground Station/Flight Controller. Is it necesarry to have both connected at all times during the flight ? I read that there are telemetry modules, but can I simply load missions onto the flight controller and the plane will fly it even though its not connected to a ground station (laptop) on the flying field ?

  6. Can I use basic analog servos ?

I hope everything until here makes sense, using a spacious platform and keeping things relatively basic for the moment. Please share what you think, I’m still a greenhorn when it comes to Pixhawk but I really want to learn using it ! I hope you experienced guys can answer my questions and assist me building the bird :slight_smile:

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Hello everyone,
Some time has passed and I could answer most of my questions myself. What I’ve done so far is soldering the complete essential cable tree as of proof of concept and learned about mission planner. Furthermore I’ve built the pan tilt system, which should hang below the aircraft. In addition to that I’ll install some basic lighting to the airplane.
I’ve successfully set up my crossfire and my dx9 and it works flawless. I’ve also switched my plan around a little bit with the channel outputs. That’s how I have planned it so far -
Ail/ele/thr/rud/pan/flaps/tilt/flightmode
I’m happy that it works so well. I hope that when I set the additional channels to rcpassthru, they are controllable on auto modes. So the next step will be to integrate the electronics into the airframe. Which may take some time.

So, am I correct with the assumption that I can rc pass thru functions when in auto mode?

yes, just set the SERVOn_FUNCTION values to pass-thru from the channel of your choice.
If you set SERVO9_FUNCTION=1 then it passes through from the same input channel (channel 9 in this case).
If you set SERVO9_FUNCTION=58 then it would pass through from channel 8 input.

Not sure what questions you’ve figured out but I’ll try to answer a few of them:

Yes, you can use analog servos.

You can upload a mission into the plane, at home for example, then take it to the field without a GCS and fly it. Yes, the plane will fly without a GCS. The down side is you won’t have any data. The cube doesn’t have an OSD but you may be able to add that in so at least you’ll have some information on your video feed.

You can set up your outputs in any order or configuration you want. Yes many people use AETR but most of my servo outputs are mapped differently and it’s not a problem.

You only need 1 flight mode. You have the option to have 6 available. If you have the channels you can even sneak in a few more but that may be getting carried away. If manual, loiter and auto are all you want then go for it. Since you have the Cube Orange and Here 2, you may wish to add in at least RTL. It’s doable on the DX9 to set up switch combinations to access more than 3 fight modes with only two switches and one channel.

If you fly out of range or failsafe for any reason, the reaction of the plane is all in what you’ve setup your fail safes. If it’s in auto, you can have it continue or RTL. What do you want it do do?

Loiter … pan/tilt … servo pass-thru. Looks like that’s covered.

The Beaver is a great airplane. I’m going to guess you’re coming from an experienced RC background with that plane. If that’s so: My advice for you would be make sure it’s flying good in manual mode first before you try out loiter or auto mode. If you plan to use those modes then you’ll need to spend some time tuning the flight controller.

I’m sorry if you’ve heard this before, but also if you are an experienced RC flyer you will need to teach yourself to NOT use the trims, rates, or mixes on the radio. All of that needs to be done in the flight controller.

Thanks for the information :+1:

Allister, huge thanks to you for taking the time and answering my questions in depth.

Regarding not using a ground station - as I use a Crossfire with 868mhz I was thinking about getting a telemetry radio with 433mhz to cover that issue. But Im taking baby steps first and add hardware as soon as the plane does its job properly. As for OSD I’m using a TBS Core Pro, which basically gives a lot of information already by itself ( it has a GPS attached as well, I just hope the TBS GPS and Here2 GPS dont interfere but that shouldnt be the case ). So information about battery, current, home position, RSSI and so on are properly displayed.

The servo outputs are configured now, the only struggle Ive had was figuring out that the mode switch seems to be default on channel 8.

Regarding flight modes. To tune the airframe I thought about using Manual, FBWA and Loiter. The reasons for that are obvious I guess. As soon as everything works, Ill switch them around. Thank you for the heads up on the mixing, thats great, Ive read about that however didnt study until now how it really works. But thats a good point, thank you !

As for the failsafe I think I actually need to study the subject a little bit more before I can ask more specific. I guess more on that before I get closer to the (re)maiden.

One small thing regarding the servo pass thru - whats the difference between RC IN and servo pass thru ? I couldnt really find documentation to RC IN ( sure the name is obvious, but there should be a difference over all since these options exist ).

Your assumption is right, I do come from a pretty experienced RC background. So flying and setting the bird up properly wont be the difficulty, tuning it to fly brilliantly before throwing missions at it will be the difficulty I guess.

Thanks again for the heads up with mixing and trimming etc. As of now I have basically on very marginal things on the transmitter, which channel does what and yeah, I guess you get the point.

One more thing though, regarding the Here2 GPS. I will have as I mentioned 2 compasses on board, one for the TBS Core and one for the Flight Controller ( Here2 and TBS GPS ). Can or will there be interference ? I will space them out properly, thats for sure.

Second, I get the point that it should be placed with clear view to the sky. Im just wondering, is it so much worse if I place it inside the airplane ? Its Balsa so it shouldnt be so much of an issue, or am I missing something here ?

Third, the calibration in mission planner. Ive watched a painless360 video where the the mission planner surface on the compass cali page looks pretty different. How does that work for the “new” mission planner ?

Fourth, is there anything else I need to do to make the Here2 work properly with the pix in mission planner ? So far its just connected and blinks a bit. I didnt achieve gps lock yet, but thats no wonder since it didnt leave the basement yet.

Thanks in advance for taking your time, I highly appreciate that !

For the tuning for FBWA read up on Autotune mode. It will help you set up the PID controller. For something like a Beaver it should do a decent job. There are always those who will say you can get a better tune if you do it manually, but unless you know what you’re doing that can be a real mess and take a long time. Also you get to a point where the laws of diminishing returns kick in.

RC is the input from the receiver. The RCx_OPTION is to assign that channel for the FC do a task. That task may be external, such as a servo or motor; or it could be internal such as a flight mode. SERVOX_FUNCTION assigned the output task. A key point is that the servo function does not need to be on the same channel as the RC input. If you are using pass-thru then the FC does nothing with the signal, but route it from what ever RC input to the appropriate SERVO output.

You shouldn’t have a problem with the two GPS antennas bothering each other. The wiring to the motor, servos and radio are a bigger problem. Try to keep that as far as possible. If you space out the antennas you’ll be okay. I also don’t think a balsa build will be an issue for the GPS antenna. I get full GPS lock with a Here 2 and Here 3 GPS in my garage, so a little bit of balsa should be okay. :slight_smile: Make sure the Here 2 is pointed in the right direction and it and the FC mounted well before you do the final calibrations.

I’m on the wrong computer to give you a screen shot, but if you’re using the latest mission planner there’s one button for normal calibration. Usually you get the plane plugged in, powered on and trigger the calibration. At this point you try to move the plane around in all axis and watch the green bar move towards the end. With a cube orange and Here2 you’ll see two green bars moving because the Cube has it’s internal compass.

Now, I’m not sure how big your plane is, but I’m going to guess it’s probably bigger than the foamy wing that Painless360 is swinging around. In that case you will notice there’s another button for Large aircraft calibration. In that cause you have the plane outside and lined up on a known heading. Once it has full GPS lock you can enter it’s physical heading and it will use that to adjust the compass. I’ve used it couple times and it seems to work well for me. Easier than trying to dance around a 3m+ plane.

If it’s connected and blinking it should be working. Might be worth just taking it upstairs or even outside if that’s an option and see how it does. My experience with the Here GPS is they lock on target pretty quick once they’ve got a view of the sky. A basement might be just a little too much, especially if it’s a first lock. You can check the hardware list on the Mandatory setup page to see if the GPS is showing up.

hey everyone,
thank you again for your great and informative in depth answer @Allister !
Ill surely use Autotune. I’ve read now through the topic and watched a video or 2 about how it works. Shouldnt be too much of a challenge.

Thank you for clearing me up about the RC terminology and its contents. That really helped me a lot. I have some channels that I wish to just get “passed thru” and therefore have set it up that way now ( pan tilt and flaps to be precise. These for now should stay under manual control ).
The actual Flight Mode switch, does it matter which input/option I assign it to ? Its now set as RC IN and seems to work properly, as I have heard about never change a running system I have left it at that so far but actually dont know if it does even matter or not what its assigned to.

Thanks as well for clearing up the issue with 2 GPS. I will try to keep everything noisy low on the fuse and get the GPS’es, RC RX and vTX near the top of the fuse. Ive ordered 10m of spiralled servo wire and will use it everywhere possible. I hope that helps me a bit as well. For the vTX I ordered a shielded cable and probably have all the servo wires on one side of the fuse and the vTX cable on the other. I guess there isnt more I can do.

This point got me a little bit. Actually if I mounted the GPS ontop of the fuse, I will point in the same direction, but the angle in which it is mounted wont correspond the the angle the FC is mounted like. Is that an issue ? Or should I build a small console where the GPS can rest on on the same angle as the FC ?

Ill probably do the compass cablibration directly on the field, this should give me best results.

Its got a wingspan of 2.25m, ~90inch

This one will do, thanks for the heads up !

Another thing I havent found an answer to but should be obvious is following. Our runway is a little sloped, which means Auto Takeoff and Auto Landing is not an option. For now I dont want an airspeedsensor to keep everything easy so far, which adds to that point. SO, if I was to plan an auto mission, can I manually take off, flip the flight mode switch and the aircraft will start the mission on the first WP or does it have to have a Takeoff as first WP ?

I know, a lot of newbie questions, but as I got noone to clarify certain things, I gotta ask what I gotta ask… Thank you really for your effort that you put in answering them questions.

So basically what Ive planned is to cut open the fuse on top from behind the wingbox on until the vertical stab. The servos will be moved all the way to the back. So I got a big hatch to access the rear of the plane, where, as I mentioned, the RX and vTX and Compass(es) will find their place. Battery and ESC and power modules all the way to the front, the FC pretty centered in the middle.

Space should hopefully not be an issue. The metal thingy will be removed, same as the wooden parts where originally the pilot found its place. Talk about replacing men with machines.


What Ive built as well yet is the observer station that will be placed on the belly of the plane. Its basically a sailwinch servo which is capable on 360° pan, moving a carbon fiber rod with an adapter for the GoPro and the FPV cam, which sits on a tilt mechanism. Hopefully at some point in the future all is manually moveable while the plane flies its auto mission.

So far - next building step might take some time.

PS : What Ive done as well is I have coded myself a small program that directly shows me how far I can fly and what flight time I get out of which battery.
Flugzeit refers to Flight Time, Reichweite means Range. It is to play around, the values I used are very conservative yet still impressive. The Batteries I plan to use are 6s 3600mah and 6s 10ah, depending on the mission on parallel.


( I know, 40A wont be what the Beaver will pull, still as I mentioned, its to play around first and get rough data on what could be possible ).

For the GPS, there is a limit to how far off level the antenna can be from the FC but I wouldn’t be too worried about it. As long as it’s reasonable. Just make sure you do the calibration after you have everything mounted and it shouldn’t be a problem.

2.25m, Yes, you can do the compass dance with that but it’s not much fun.

Airspeed sensors aren’t a big deal to set up. On the Beaver it would need to go out on the wing to get out of the slipstream of the prop. But the performance of the plane in automatic modes is better. That said, Arduplane will fly just fine without an airspeed sensor, and you can still do auto take-off and landings. You just need to be a little more conservative with your speeds, especially for the landing.

Many of my planes I will take off in FBWA and then switch to Auto once I’m up and away. In that case the first command in the mission can just be a waypoint. Just for my own peace of mind when I do that I will climb to a reasonable altitude and point roughly towards the WP. I know my plane will do it just fine from any direction, but for the heavier long range planes I don’t see the need. (Smaller FPV, yank and bank!)

Looks like a great plane! I’ll be watching to see images of it in the air. Once upon a time, when my hair was a little darker, I spent a lot of hours traveling around the country in Beavers and Twin Otters. They are great machines.

Once you’ve got it in the air you’ll be able to look at the flight data and dial it in to maximize your flight times. Again, if you are going to push for longer endurance then an airspeed sensor is worth considering.

Allright, I’m gonna take care of that. Ill have to see how I properly integrate it into the plane though.

Regarding the air speed sensor, Ill have to see if I use it initially, however I got myself now a Matek 4525 ( Matek Systems – Digital Airspeed Sensor ASPD-4525 – 3DXR – Unmanned Aircraft Systems & The Cube Autopilot ) I hope that one suits the Pix2.1 just fine. I see that it has to go far into the wing. As I need to do all the wiring new anyway, well, I guess Ill have to use even more of my drilled cables to connect that to the FC :wink: Thats gonna be a long day of soldering for sure.
For the positioning of the AS Sensor, the further out the better it is I guess ?

Good to know that its common practice to do it that way.

You will be the first to see for sure ! :slight_smile: I’m really looking forward to building and finally setting up the bird. It might take some more time, but Ill keep any progress posted here.
Wow, seems like you are a seasoned bush pilot, I hope my plane will live up to your expectations as well !

Allright, will do !

As I mentioned, new updates will now be infrequent, I might take a month or two. Thank you so far for your input, its worth an awful lot ! Whenever you come up with ideas on how to improve the build from beginning, just throw your thoughts at me and Ill try to implement them.

Until then !

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Servers by jDrones