[andre.g]

is it possible to configure librepilot in order to have yaw by differential thrust of the motors?
I have a flying wing with two motors but no rudder.
thank you

[f5soh]

yes, can be done adding changes to the mixer table.
Like differential ground vehicles.

Your wing is "elevon" type ?

[andre.g]

yes

[andre.g]

thank you for the answer, but i'm a newbie so i don't know how to add mix, could you explain?

[f5soh]

Follow the wizard and configure as a normal elevon wing.

Import the uav file attached, this change only the mixer table and keep the original config without modifications.

Here is the original elevon wing diagram:



After you imported the "mixer file" you should reboot the board and adjust the min / neutral / max in Output tab, same a the first motor you configured with wizard. (Assuming both Esc are calibrated the same)
Right motor is connected to output4 and left motor to output3, if something wrong you can swap output4 and output3.



Remember if you save the settings while you are in vehicle tab, mixer table will be reverted to normal motor scheme.
Throttle curve reduced to 80% max is normal, this give some room for Yaw stabilization at full Throttle.

[andre.g]

Thank you very much!

Inviato dal mio ALE-L21 utilizzando Tapatalk

[Camperinho]

Hi,

I'm trying the same, but with a "standard" plane, only Rudder is missing and should be compensated using the two motors. I've tried importing your .uav file, but then i'm also have a "elevon" mix, which I don't need.
I've attached my current mixer as screenshot. Any advices?

[f5soh]

Assuming motors are connected to output 3 and 4, you miss:

- Curve 1 to 127 for output3 (give Throttle response)
- Yaw value for output3 and output4, should be (3)127, (4)-127 or (3)-127, (4)127 for differential thrust using Yaw

Reduce Throttle curve to 0.8 / 80% max

[Camperinho]

Great! Thank you very much!
Another short question: What does these magic numbers mean? means the exact value 127 just "activated" and everything beside that will be ignored?

 

[f5soh]

127 = 100%

[newtoon]

127 = 100%

Hi ! I don't know if I can get an answer, but I have a light flying wing that was reluctant to turn effictively without differential thrust and I used your trick I think (reloaded the .uav from here, so dunno).
In my future tests, I would like the yaw to be slightly stabilized as well (via differential thrust) and even more, to try to get a bit of differential thrust when I apply a roll. What change in the mixing and other parameters should I try please ? Thanks in advance

[TheOtherCliff]

In my experience, stabilizing yaw causes problems.  With stabilized yaw, you must coordinate your turns (in a banked turn, after banking, you must hold some rudder the whole time you hold elevator) in every turn (except for 90 degree banked turns).

Yes, it is possible to mix some yaw into the roll function.  Generally you can mix anything into anything in either a custom mixer table in the flight controller or in your transmitter.  The problem with this is in most flying, you bank, let off the bank stick and it stays at that bank angle, then apply and hold elevator, then release elevator, then "unbank".  You need the yaw during the whole time you are pulling elevator, but you are not holding any roll then, so you won't get any yaw even if you do mix some yaw into your roll (any of several ways).

Using a uav file from a different airplane type is not something I would recommend.  Instead, understand what it is you need and apply it to your current settings (which should be kept as close to default as possible for simplicity's sake, don't change things without knowing what they do).

With unstabilized yaw, did the airplane turn better in one direction than the other?  If that is the case then the solution may be to manually add some permanent "rudder trim" or learn to coordinate your turns.

You didn't mention what flight controller you are using or whether (if it is a Revo class FC) you will be doing GPS flight modes.

[newtoon]

Yes, it is possible to mix some yaw into the roll function.  Generally you can mix anything into anything in either a custom mixer table in the flight controller or in your transmitter.  The problem with this is in most flying, you bank, let off the bank stick and it stays at that bank angle, then apply and hold elevator, then release elevator, then "unbank".  You need the yaw during the whole time you are pulling elevator, but you are not holding any roll then, so you won't get any yaw even if you do mix some yaw into your roll (any of several ways).

thank you very much for the reply, and lol, i quoted you because that's exactly how I like it !!! It all came from 2012 when I discovered (I was not in the hobby till then) toy quads and I fell in love with "angle mode" (betaflight). I fly all my numerous ONLY in stabilized mode now, mostly with CC3D, in FPV or LOS. It suits me, I like the sadistic "resisting feeling" in the sticks ; it is a bit satisfying for me that my quad wants to come back to boring level. Furthermore, sometimes, I screw up and I like that my quads carry on level and I have a small window to correct things by letting go and not fall in a stupid spiral and break things (I don't like breaking stuff because ... I'm broke, lol).

So, only one of my planes, a 180 gr Fournier, has yaw stabilized now and it flies on rails : (sorry for the quality, my teen daughter filming with her smartphone...) despite gusts. it's deadly silent. Perhaps one solution for yaw stab is just to put less stabilization strength on it ?

But right now, I'm testing yaw differential and it works very good, since I'm so used to turning wings with just banking and elevator, that I just would like a tiny bit of differential, because this very wing (it comes from a toy that I mounted brushless on, a B2 bomber 700mm around, 120 gr 2S) just wants to go straight forward otherwise without me thinking "oh, yeah, add yaw or it won't turn or only very big turns). I would like to bank and differential comes into play like 10%, that's all.

How can I do that please ?

[TheOtherCliff]

By all means do use (unstabilized) thrust differential for yaw.  I just think that stabilizing yaw causes problems.  In LibrePilot, just set the yaw to Manual.  You can still use yaw that way, it just won't automatically add right yaw (that you must correct) when you are making a left bank.

I actually fly quads in self leveling mode too (LibrePilot calls it Attitude mode).    I play with GPS flight modes a lot and it is just a natural extension of that.  Also, everyone flying FPV should have a self leveling mode (or RTB or other GPS flight mode) available on their switch for when the video goes out.

[TheOtherCliff]

Do you know how to set the yaw stabilization to Manual?

Have you now tried that and did it help with your problem?