First FPV Wing - Need INAV/Servo help

[LStanford]

Hello all,

I've been doing RC everything for nearly 30 years, but that's mostly old school helis, glow planes, cars, and boats. I'm just getting started with foam/electric/brushless stuff. I recently got a mini arrow and decided to go full tilt FPV with GPS, etc. I've run into a problem with the servo setup, likely in INAV. I've searched many forums and many videos but I can't find anything that describes a similar problem or a solution so I'm seeking help. Happy to provide videos if needed.

Setup: Mini Arrow, Mateksys F405 v2 FC,GX12 Gemini TX, XR4 RX, Flight Test Power Pack F, AKK VTX, Runcam Phoenix 2, and a GPS receiver.
- Additional specific to the problem: Motor is on TX Ch.3 - FC S1, left elevon TX Ch. 2 - FC S3, right elevon TX Ch.1 - FC S4

First, since I've been asked by others...yes, I made all that fit inside the mini Arrow and balanced it. I'm pretty good at 3D printing so I made minor mods.

Problem:
- In INAV, my transmitter, receiver, and FC all seem to be receiving the right mixes for a delta wing elevon input. However, on the output page and in reality the servos are not responding correctly. When I use L/R aileron input the right servo throws 100% instead of 50% and the left servo is throwing 5-10%. When I use up/down elevator input the right servo is throwing 5-10% while the left servo is throwing 100% (exact opposite of aileron input).

- I've check my TX mixer and it is setup correctly in accordance with literally every video and guide I've found.
- In INAV I've selected "wing" and ensured the servos are connected to S3/4 respectively. In the receiver page, the inputs seem to be correct for what the transmitter is sending.
- I've checked the FC to servo connections, done voltage checks on the power line.

At this point I'm at a complete loss for what's going on, but I'm near certain there's some setting in INAV I'm not doing correctly.

Any and all help is appreciated.

 

[Merv]

... I've check my TX mixer and it is setup correctly...

With any flight controller or flight stability, there should be absolutely no mixing or reversing in the Tx. ALL of the mixing and reversing must be done in the FC alone.

That is for channels for flight. If you have a non flight channel, like landing gear or lights, mix & reverse in the Tx.

 

[LitterBug]

One other thing I will add to what Merv said above is that if you are not in manual flight mode, The FC is only moving the control surfaces as much as it thinks it needs to for a specified roll and/or pitch rate. You should NOT expect to get full deflection unless you are in manual flight mode. Also, the default roll and pitch rates are pretty low.

I have a ton of experience with INAV, ArduPilot, Flex Aura, and other firmware, so between Merv and I, we should be able to get you set up correctly.

 

[LStanford]

With any flight controller or flight stability, there should be absolutely no mixing or reversing in the Tx. ALL of the mixing and reversing must be done in the FC alone.

That is for channels for flight. If you have a non flight channel, like landing gear or lights, mix & reverse in the Tx.

Merv, that worked. Thank you! 8 days of searching fixed that quickly...should have gotten on here sooner.

 

[LStanford]

Onto the next problem now...throw rates for the servos. In INAV and in manual mode I've setup the Output page to give me 85%, which is what gives me the Flight Test recommended low rate for angles on the control surfaces.

What I'm trying to do now is tie a switch on my radio to change from low to high-rate mid-flight. I went into the adjustment tab per the instructions and was able to assign the switch but the instructions on slot and via channel are confusing. Nor do I see anywhere where I can set what the rate change is.

Once I figure that out then I'll get into what I'm assuming is non-manual mode...I'll have to look that up.

Thanks!

 

[Merv]

...What I'm trying to do now is tie a switch on my radio to change from low to high-rate mid-flight....

I'm thinking you need to set the output page to give you the throws you want in high rates. Then setup high & low rates in your Tx.

Here is a video to setup duel rates within iNav

 

[LStanford]

Ha! I found the other video by this guy but missed this one. I sincerely appreciate both of your help.

 

[LitterBug]

Please share video once you get up and flying if possible! Always good to see where everyone flies.

I find the stabilized modes are more comfortable to fly in bumpy conditions, especially on lighter birds. I have been flying sub 250g and some bigger planes too. Mostly Strix Nano Goblin and Stratosurfer. There are days where the nano goblin is just too light, but the Stratosurfer being heavier and bigger will handle it like a champ.

Cheers!
LitterBug

 

[Merv]

Keep in mind the output page is there to limit the total maximum throw. This is to prevent binding from the servos traveling too far, similar to the old school end point adjustment in the Tx. Once you have limited the maximum throw, then use the other settings to adjust the throw you want.

In settings up a flying wing, many use a 50/50 settings on elevator & aileron. Thinking this will prevent going over 100%, which is true. The problem is you can never get 100% elevator or 100% aileron travel.

I prefer to use a 100/100 elevator/aileron mix. Then use the output page or end point to prevent over driving the servos. This gives me the elevator & aileron travel I'm looking for.

I'm relatively new to iNav & still have a lot to learn about it. LB has been a tremendous help in my iNav journey. But that is what this forum is about, everyone sharing the knowledge they have so that all of us can benefit.

 

[LitterBug]

That is the cool part about this forum, is we are all hear to learn from each other.

 

[LStanford]

Ok, I've gotten everything I can setup and I'm ready to maiden. I still need to workout the the FPV portion, which is fine for later (need to connect Cobra X v4 to AKK Race Ranger and see if my INAV settings for changing power settings on a switch work).

I wanted to post my final setup and the 3D print files I made so if others want to setup something similar they can. Its CG is balanced to 1.2 mm forward of Flite Test's recommendation with the battery in.

Running: Mateksys F405 Wing v2; XR4 dual band (internal mount along opposite wing from video antenna); M100 GPS; Runcam Phoenix 2; AKK Race Ranger VTX; AXII RHCP antenna

Picture 1: Clean and how it will fly
Picture 2: Opened center for battery install and maintenance on wires, etc. Everything is removable (no hardwiring)
Picture 3: Box and lid CAD drawing
Picture 4: Antenna grommet (I create this to keep the antenna from damaging the foam)

Since I cannot upload the 3D print files, they are located on Printables.com at:
Printables - Mini Arrow Mods

 

[Mr NCT]

Since I cannot upload the 3D print files

You can upload them to the "Resources" section. If you have trouble holler 🤓

 

[LStanford]

You can upload them to the "Resources" section. If you have trouble holler 🤓

It doesn't look like it accepts .3mf files. I'll have to pull them in .STL or G-code for it to accept. Let me know if I'm missing something.

 

[LitterBug]

It doesn't look like it accepts .3mf files. I'll have to pull them in .STL or G-code for it to accept. Let me know if I'm missing something.

Can you put it in a .zip file? I believe it will accept those.

 

[LStanford]

Update: Well, the maiden didn't go so hot. I checked the balance 6 times, checked the elevons 3 times, and it did a left roll right on launch to a crash. The front end is totaled but I think it can be salvaged. The battery flew out on impact...Ha!

 

[Bricks]

One of the biggest mistake made with flight controllers make absolutely sure the gyro is correcting in the right direction. Got caught on this one myself.

 

[LStanford]

Ok, back again. I've completely rebuilt the front end box with locations for the components, which is way better for organization of cables, etc. Somehow it's actually less weight...

Now the problem that's been plaguing me:

1) For some reason my AKK Race Ranger VTX that worked before won't toggle power on my dedicated switch throw. I had a program setup to push a button and toggle from power 1 to power 3, but now it seems to not register that program. It's registering the switch throw, and the program says it worked, but the physical lights on the VTX do not change. I've checked that SmartAudio is selected on UART 3...nothing. Any help here would be appreciated. There's now an INAV setting in config for VTX and I'm wondering if that's overriding it, but even if I default it to power 3 it doesn't work...it's like the smartaudio isn't pushing info.

Attached are my INAV settings. The VTS settings will always revert to F 1 1 even if I change it to something else. The program is identical to what I setup before except I think I had the higher value 3, but 4 should still work.