Beginner building TurboBeaver / Your input is welcome!

TurboJet · December 7, 2020, 12:13pm

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 :

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 ?
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 ?
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.
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 ?
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 ?
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

TurboJet · January 9, 2021, 8:25am

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?

tridge · January 9, 2021, 9:39pm

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.

Allister · January 10, 2021, 3:47am

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.

TurboJet · January 10, 2021, 9:57am

Thanks for the information

TurboJet · January 10, 2021, 11:40am

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 !

Allister · January 11, 2021, 12:49am

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. 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.

TurboJet · January 12, 2021, 5:12pm

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 ).

Allister · January 13, 2021, 12:42am

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.

TurboJet · January 13, 2021, 9:04am

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 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 ! 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 !

TurboJet · January 26, 2021, 9:39pm

Hi again,

The build progresses slowly, nothing noteworthy regarding the plane itself so far to post here. However something is odd with my gps or more likely my settings and I guess I’m doing something fundamentally wrong with it.

Super basic, the gps is plugged into GPS 1 Port on the board.

Then I go to compass calibration, where in the compass calibration Ive set it up this way ( its pretty much default, all compass parameters are default and the switch inside the here2 is on i2c) :

I shifted the I2C Compass to priority 1 ( I guess thats the Here2 ? ). When I do the onboard Mag Calibration thing, Mag2 always get a success ( I guess thats id1 ), Mag1 doesnt. It runs through just to go for another try. And another one. And so on, it wont stop. Even if I do it 20 times in a row. I clicked accept at that point.
When it says Onboard Mag Calibration, is that even the Here2 Im calibrating or simply the internal compasses ? And are the gps’es in the correct order ? What am I doing wrong here ?

As a result, the gps wont ever find a lock ( I’m now in the 5th floor where it should easily achieve a lock ). It just happily blinks in yellow and on the data page I only get this : Unhealthy GPS
compass2
Nothing is connected so it says failsafe I guess.

Can anyone clear things up for me please … no idea whats wrong

Basic tuning and standard params

I see Autotune will tune my Roll, Pitch and Yaw PIDs. However theres also an option to set thrust 0-100% where you can adjust percentage of cruise throttle. Why is that important? Since I set cruise to 20 m/s, shouldnt that be the target airspeed whenever its in some sort of auto mode ?

Further Ive looked through the standard params, is there anything I need to adjust ?
Regarding the air speed sensor, with that I wanna play around later when I know the plane behaves well.

What bothers me the most right now is the GPS, if someone can help me I would highly appreciate that …

Allister · January 27, 2021, 4:09am

Yes, it the failsafe is because you don’t have the RC connected.

When you’re calibrating the compasses do you have both of them moving together? On the Cubes I will tape the GPS to the top of the cube so they move together when doing the initial calibration. The onboard calibration is calibrating both compasses at the same time.

The calibration alone shouldn’t affect the GPS fix. This is suggesting to me a another fault some where. Check the GPS is showing up on Setup/Mandatory Hardware/ HW ID. Verify that the serial port is set to GPS. I think for that one it should be SERIAL3_PROTOCOL = 5 (but you might want to check that)

Another option would be to convert the HERE2 to CAN mode and try it in the can port. https://docs.cubepilot.org/user-guides/here-2/here-2-can-mode-instruction

Allister · January 27, 2021, 4:31am

For the tuning, I’d leave the defaults for the first flight. Especially since you’re comfortable flying manually. If the flight controller goes bonkers in a stabilized mode, make sure one of your flight modes is “manual” and have that on a switch you can reach quickly.

Autotune will only adjust pitch and roll. It won’t do anything for yaw. But that’s usually not an issue. Leave the throttle min at 0. You can adjust the max for planes that are over powered. There is also a separate throttle max for take-off. For example you could have 100% throttle for take-off but only 80% during all other flight modes. This would only apply if using a specific take-off flight mode. In your case I suggest leaving that at 100% for now.

The cruise airspeed (TRIM_AIRSPEED_CM) will only be in effect when you have an airspeed sensor. Otherwise it will use TRIM_THROTTLE. Again, I’d leave defaults for the first flight. Without an airspeed indicator you would fly the plane manually or FBWA and note roughly where you’ve set the throttle for your normal flight. Then you can enter that value in to the TRIM_THOTTLE. Even if are using an airspeed sensor you should set that. It will default to that if the airspeed goes offline, and you’ll want to fly the plane without activating the airspeed sensor initially to calibrate it and validate it’s functioning.

When it comes to tuning, the first priority is getting the plane to fly well mechanically. All the usual things. C of G. Mechanical Trims. I use SERVO_AUTO_TRIM=1. This will do exactly what the name says. Then after the flight I’ll check where the new neutral are. Then I’ll mechanically adjust the push rods to the ailerons or elevators as needed so the servo is neutral with the control surface in the desired trim location. Just like you’d do on a regular RC plane. You will see the trim values on the Servo settings in Mission Planner. Default is 1500. If after trimming it’s between 1450 - 1550 then I don’t get too worried. If it’s outside that range then I’ll make more physical adjustments. (and of course double check there isn’t something else make the plane need too much trim).

Once you know it’s mechanically good, then Autotune. Once you’re happy with that then you can get into TECS, take-off and landing tuning. Those you only need to take as far as you want to go. All depends on how automated your flights are going to be, and what kind of performance you’re looking for.

TurboJet · January 28, 2021, 11:30am

Hey Allister,
you really keep my hopes alive to get this bird eventually airborn.
I havent taped them together, Im actually just using both hands and moving the FC and GPS. When I did the very first calibration, I strapped them together but had the same result.

It shows as : Compass_Dev_ID | 592905 | I2C | 1 | 12 | AK09916

I also checked the serial protocol, its set to 5 as you said it should be.

I have yet to test that, might take some while since Im not near my shop right now…

Edit : Got it to work, its ready to be installed. I dont know where the mistake was, probably it was because the compass and the fc were not aligned together in one direction which gave the system conflicting data.

Thank you so much as well for instructing me how to use the different parameters. Ill follow exactly along the steps you mentioned.

Allister · January 28, 2021, 3:00pm

Part of the calibration process is the system identifying the differences between the two components. They don’t have to be perfectly aligned, as long as what ever difference they have is consistent.

Glad to see you have it working!

TurboJet · February 6, 2021, 1:17am

Quick question just to reassure myself - how close can tail servos, vtx, rx and gps’ be together? Are ~5cm apart from each other enough or will I have to move certain devices? Is it ‘better’ to have GPS and vtx close together or have rx and vtx or rx and GPS closer together?
The power stuff is all up front, I just struggle to optimally place the 2 gps, vtx and rx. Any input is highly appreciated

Allister · February 6, 2021, 10:08pm

Depending on your RX, having GPS and RX close may not be an issue. If your RX is sending telemetry back then it should be further apart because it may impact the compass. The VTX should be as far from everything as possible. It’s typically broadcasting at a higher power than the RX and will cause interference. On your airframe you should have lots of choices. It may not feel like it, but imagine trying to fit all that gear into a small multi-rotor.

You should also consider separating the servo leads from the leads to the VTX and RX. I’ve had interference from those before that caused the servos to be excessively jittery.

TurboJet · February 7, 2021, 10:14pm

Allister,
your input and knowledge is of such a high value for me, thank you so much again. To display the situation better, I took some pictures so you (guys) might be able to evaluate the situation better ( the plane is a huge building site at the moment, so please dont judge me yet on wiring, Ill handle that when the components positions are determined ). Let me just bomb all the photos to you to get an impression of the space I have available :

This is how “far” the VTX and the RX are apart from each other. I heard servos have a lot of electronic smog ( sitting below and a little further back of the VTX ), so I cant really go further to the back of the plane with the VTX. Personally I’m not a fan of moving the VTX to the wing - if I have to, I will of course. The fans are necessary to cool the VTX down. Are these too close to the vtx ? Theoretically I can move them to the bottom of the plane, which gives less cool air but maybe less interference ??

Here you can see the cover held to the rear fuse. In the aft section you see the servos mounted. 2 Ele Servos, one Rud Servo. As you can see, moving the vtx further back would place it directly and in very close proximity the the servos, which I wanted to avoid. Due to the length of the Crossfire Antennas, I couldnt move the RX further to the front. I could turn the RX around with the antennas to the back, but I guess its more important to have the anntenas serparated than the actual electronic devices themselves.
On the bottom left begins the middle section of the plane that houses the GPS. BTW the RX does NOT send telemetry back and I dont plan on that in the future. Just receive. So I placed listening stuff to listening stuff if that makes sense. I hope the GPS will work on that lowered position.

With the cover closed ( I didnt install hinges yet ) it looks like that from the inside ( again, I know I need to arrange the cables when the time comes ). Can I leave it like that or which changes would you make ? To all disadvantage I somehow need to position my second GPS anywhere in there as well. The second GPS will however probably sit a little further back of the “main” steering gps and lower in the fuse. Ill maybe just have to test if it works or it does not…

The very front section will all be BECs and Battieries, where the Mauch Sensor is lying there begings the secondary section of the plane. I planned to just accommodate the FC there, however there would theoretically be space for other electronics. However, directly above runs the full aluminum wing spar.

So, these are my thoughts and guesses. What would a professional say to all that ? What can and should I improve to get optimal results ?
The wings are not really an option, as they are foiled and pretty thin obviously. Finding a way to fit the airspeed sensor will be a challenge for the future.

I’m happily awaiting input, have a nice sunday guys and hopefully I hear from you soon

btw :
put it together for the first time ( shes so pretty … ) :

Allister · February 8, 2021, 3:31pm

I think most of the placements should work. The electronics above the GPS antenna may not be ideal, and may degrade the HDOP, but I’ll bet it will still be more than adequate.

I’m worried about your cooling, that you need the fans for the VTX. Is the fuselage that airtight? I’ve never done it, but since you’re using a crossfire RX and TBS VTX could you use smart audio to turn the VTX to low power while you’re on the ground then power it up once you’ve got airflow in flight? What are you doing for cooling for your ESC?

You’re right, that’s a pretty airplane!

TurboJet · February 8, 2021, 4:17pm

Allright, well I think I’m gonna test it like this, if it doesnt work properly Ill put the GPS on top of the fuse.
Can I read the HDOP value somewhere when I’m connected to the pix ?

Actually the fuse is not especially airtight, but there is no major airflow either. A NACA duct or an air scoop would be an option as well, yet I found that the vtx gets extremely hot in short time, hence the fans. Given I need probably 5 minutes at the field to get everything started up and running, I surely would cook the vtx. I need to read more into the solution with the smart audio I guess, yet it gives me another source for mistakes…
The esc itself is dimensioned properly, its a 100amp esc, the powertrain will max out at around 89amps. During cruise I wont need anywhere that amp rating so I think I’m good to go using it as it is.

Do you think the fans are a bad idea right there ( interference wise ) ?

Yet I feel like I’m using too many BECs/Power Modules. I have one Power Module to power the Pixhawk (the Mauch), one to power the OSD / FPV cam, another one to power the VTX ( cant really power 1W+ out of the TBS Core. The manual says it maxes out at 1W, the Unify’s are known to sometimes put out more than 1W). Fourth, I have a BEC installed to power the servos.
Thats due to the different voltages needed…