Hi guys, I am considering buying one of those cheap CC3D flight controllers to use on a more or less trainer plane with the ability to let go of the sticks and letting the craft stabilize itself automatically if I get into a bad spot.

Mostly I found this functionality very useful in my Apprentice S15e and it's SAFE receiver functionality. The panic button is extremely useful when learning, I love it.

Also the limited pitch and roll would be nice to have too, is that doable on here?

Aaand final question, how does LibrePilot compare to ArduPilot? Looks to me like LibrePilot is still kind of active on it's development and is available on cheaper boards, the cheapest ArduPilot boards are the Pixhawk and the deprecated ArduPilotMega.

Thanks for any and all answers and advice!  :)

Yes, but...

Probably the best way to set up an FC for an airplane is to get the airplane flying and trimmed out without stabilization, then with Rate stabilization, then finally with Attitude mode stabilization.  Attitude mode is what you want for your panic button and it will quickly level it out from any position.  You can see that this is a chicken and egg issue if you need the Attitude mode to fly the airplane.

May I suggest that you find a local club and get help from experienced pilots.  Also, an RC flight simulator is a good cheap investment.  You can get either a universal USB adapter that works with your transmitter, or a USB transmitter joystick box; and then an RC flight sim program.  There are several programs that are free.

If you can't find a club and need the Attitude mode, someone here could give you the settings that he flies his airplane with, but they won't be guaranteed to work.  I have some Bixlers configured with the most aileron deflection possible without binding and elevator throw that feels like it matches that.  I find that they need 2 to 3 times higher roll rate and pitch rate PIDs (0.00800,0.0175,0.000089) than the defaults (0.00300,0.0065,0.000033) as displayed on the Stabilization -> Advanced page (Rate Stabilization).  I also use 1.8,0.8 instead of the default of 2.5,0.0 for both Roll and Pitch Attitude Stabilization.  These alone may be enough to make it work acceptably.  If your airplane is more sluggish than the maxed out Bixlers you may want a bit less PID.  If you see oscillation in flight you want less PID (all by the same multiplying factor like say 0.8 ).

I generally leave my yaw/rudder set to manual and thus unstabilized and thus the PID for this doesn't matter.  I assume your airplane is 4 channel, aileron, elevator, throttle, and rudder.

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limited pitch and roll
Attitude mode will not let you get upside down at all since e.g. full aileron stick commands full aileron bank angle (55 degrees by default) instead of commanding the fastest aileron roll rate.

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ArduPilot
I would post in some ArduPilot forums and see what the response is.  I honestly don't know how "beginning airplane pilot friendly" it is.
« Last Edit: May 11, 2019, 07:05:13 am by TheOtherCliff »

May I suggest that you find a local club and get help from experienced pilots.  Also, an RC flight simulator is a good cheap investment.  You can get either a universal USB adapter that works with your transmitter, or a USB transmitter joystick box; and then an RC flight sim program.  There are several programs that are free.

OK I may have incorrectly phrased this, I am not a beginner pilot, it's just that there can be moments where I lose control, a bug rams into my eye (those bastards are smart, they figured out how to get around the sunglasses) and normally I just plant the airplane into the ground at high speed.

Also I like the idea of the plane circling around an area when I flip a switch, so I don't have to constantly watch it, or maybe if I lose sight of it.
Return to home is awesome too!

This normally wouldn't be on the cheap foamies, however I do have some more expensive models which I would REALLY hate to lose so ungracefully.

About the limited bank angle, that is very good to know! Limited pitch is also possible right?

Thanks for the answer and the config values! I will probably be doing a lot of tuning.

Trim it (with FC running) in Manual mode, then Inner PIDs in Rate mode (then Outer PIDs in Attitude mode if desired).

During the first step it's important to put the transmitter trims back in the center and adjust the linkages instead.
Second step should not need any trimming.
Third step (Attitude) should be trimmed with Attitude -> RotateVirtual...

Either PositionHold or ReturnToBase will zigzag (not circle) over the location.

Attitude mode limits what ever axis you have it set on.  On an airplane, normally you would set up Roll=Attitude, Pitch=Attitude, Yaw=Manual, Throttle/Thrust=Manual

Trim it (with FC running) in Manual mode, then Inner PIDs in Rate mode (then Outer PIDs in Attitude mode if desired).

During the first step it's important to put the transmitter trims back in the center and adjust the linkages instead.
Second step should not need any trimming.
Third step (Attitude) should be trimmed with Attitude -> RotateVirtual...

Either PositionHold or ReturnToBase will zigzag (not circle) over the location.

Attitude mode limits what ever axis you have it set on.  On an airplane, normally you would set up Roll=Attitude, Pitch=Attitude, Yaw=Manual, Throttle/Thrust=Manual

Awesome, I am going to order one and see what I can do!

I'll probably make a simple plane to try it out on first. I don't think these flight controllers work on flying wings... or do they?

Sure.  Flying wings, V-tails, etc.

Be aware that the CC3D will not do GPS flight modes with LP.

Sure.  Flying wings, V-tails, etc.

Be aware that the CC3D will not do GPS flight modes with LP.

Now that is a dealmaker.

Oh I am aware of that, I first thought I was going to go for the simple CC3D, but I guess I am going for a Revolution clone.

Cool.  The first question on the first forum I go to is exactly the question I have and the answer is what I expected.  I think I'll set two attitude modes, one for normal flying with tamer return to level rates and one with the higher rates suggested here for panic mode.

If you are talking about the PIDs, I would recommend that you just assume that there is only one correct set of PIDs.  You don't change your car shock absorbers on your sports car to make it corner like a school bus when you let your son drive your car.  Instead (if available), you may change a setting in the car so that it can't go so fast.

So leave PIDs set to optimal and instead adjust the max roll (banking) rotation rate for Rate modes, and the max bank angle for Attitude mode.

In Attitude mode, when you hold the roll stick half way over, the aircraft stays banked to half it's max bank angle.  When you release the stick back to the center, it levels back out.  I generally recommend that when flying in Attitude mode that when you move the stick, the aircraft should respond instantly (as quickly as possible) and simply rotate to it's new commanded bank angle.  There is a real reason to limit how fast it rolls in Rate mode (but not in Attitude mode, not even for a beginner).

You may want to reduce the max bank angle for Attitude mode, but I don't really recommend it.  By the time you are flying Rate mode, you will understand that you should set it so that max stick angle makes it roll fast, but still slow enough so that you can visually and mentally keep up with the roll.  Very fast Rate mode and Acro+ modes are sometimes set up so that the pilot can't actually visually and mentally keep up with it.  In that case, they develop a timed stick blip.  They know that if they hold full stick for about "that" long (say 1/4 second) that it will do about one roll.  They do it, it ends up close to right side up, and they just correct a small and slow amount from there.

If you are talking about the PIDs, I would recommend that you just assume that there is only one correct set of PIDs.  You don't change your car shock absorbers on your sports car to make it corner like a school bus when you let your son drive your car.  Instead (if available), you may change a setting in the car so that it can't go so fast.

So leave PIDs set to optimal and instead adjust the max roll (banking) rotation rate for Rate modes, and the max bank angle for Attitude mode.

In Attitude mode, when you hold the roll stick half way over, the aircraft stays banked to half it's max bank angle.  When you release the stick back to the center, it levels back out.  I generally recommend that when flying in Attitude mode that when you move the stick, the aircraft should respond instantly (as quickly as possible) and simply rotate to it's new commanded bank angle.  There is a real reason to limit how fast it rolls in Rate mode (but not in Attitude mode, not even for a beginner).

You may want to reduce the max bank angle for Attitude mode, but I don't really recommend it.  By the time you are flying Rate mode, you will understand that you should set it so that max stick angle makes it roll fast, but still slow enough so that you can visually and mentally keep up with the roll.  Very fast Rate mode and Acro+ modes are sometimes set up so that the pilot can't actually visually and mentally keep up with it.  In that case, they develop a timed stick blip.  They know that if they hold full stick for about "that" long (say 1/4 second) that it will do about one roll.  They do it, it ends up close to right side up, and they just correct a small and slow amount from there.

You man deserve a fat paycheck for doing all this, seems like you are the most active person on the forum!

Hats off to you!

karla

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Aaand final question, how does LibrePilot compare to ArduPilot? Looks to me like LibrePilot is still kind of active on it's development and is available on cheaper boards, the cheapest ArduPilot boards are the Pixhawk and the deprecated ArduPilotMega.

Hi,
I have not tried ArduPlane but Ardurover on a sailboat both using a Openpilot Revolution and a Revo mini board.
They have also ported ArduPilot to Sparky2 board. The built in radio is not supported however, that is a big minus.
I fly fixed wings (Mako) using LibrePilot and it works fine.