Traditional Heli and Pixhawk

Having used an APM 2.5 for the last year with great success I’ve now ordered a Pixhawk. I know that a number of you have now got Pixhawk flying on traditional helis. Would you care to share your experience.

Also it would be good to get a wiring diagram up on the Wiki for Traditional Helis.

Thanks in anticipation.

I’m actually not sure that anyone has put a pixhawk onto a tradheli yet although Rob has been working on putting a px4 on one.
The wiki isn’t totally updated to show the pixhawk wiring yet but we have this page: … ick-start/
For the outputs to the servos you should find that they connect to the same output numbers as on the APM2. It’s just that on the back of the pixhawk we have two sets of outputs. The “MAIN OUT” and “AUX OUT” and it’s the "MAIN OUT"s that you’ll want to use. On the top of the Pixhawk case you’ll see these two labels.

There are a couple of important points I’d like to mention at this time.

First, is the servo rail power. The Pixhawk is actually really well set up for tradheli use. The servo rail is rated for 10V and 10A, so you can use it directly for 2S battery power distribution. You can in fact hook up HV servos directly to the rail, or a 6V BEC. 10A should be enough for all but the most high-powered servos. The Pixhawk can power itself directly from the servo rail, if and only if it has 5V on the servo rail. But it will not select this power input if you have 6V or more on the rail. In that case, you will have to use something like the Power Module to supply the Pixhawk.

The PX4 however, is a bit different. You cannot apply more than 5V to the servo rail by default. To use higher voltage servos, you must remove a tiny little SMD component called L1. That is briefly detailed here: … io-wiring/

This now creates an air-gap and you can run whatever voltage you want. Another important difference, is that the PX4 has a power regulator directly on-board. However, you can’t power the PX4 from the servo rail. I fix this by soldering little jumper wires from the servo power rail to the PX4 power supply input. But there’s an additional trick here… the voltage regulator on the PX4 is only suitable for supply voltage down to 6.4V. So it’s slightly tricky to try running 2S direct from the servos. I actually have removed the switching regulator and installed a very low dropout linear regulator good down to 5.3V. So a bit of hacking.

Personally, I like the PX4 better as it has a built in voltage regulator, and is more compact. It’s hard to fit a Pixhawk on a 450, even a 600 requires some work.

As for the rest of it, I am currently having a problem with radio glitching which is why I haven’t flown yet, but we hope to have this solved soon.

I am embarking on a Blade 450 conversion using a Pixhawk and accessories (my new year’s objective). I’ve not seen a lot of posts explaining success or experience. Similar to the original poster, has anyone experiences or directions to share?
[color=#0000FF]What did you do to put Pixhawk on a traditional helicopter? [/color]
Please share pictures or videos.

Similar to Bob I would like to know of any experiences of Pixhawk on a heli. I have an Align E600 waiting if someone posts some guidelines. In the meantime I will be testing the Pixhawk on a hex.

I’m in the process of finalising my Logo 400 with Pixhawk and wanted to confirm connection details (see attached diagram for APM 2.5). Do we connect the ESC to channel 8 on the Pixhawk and the other channels according to the attached diagram.

Thanks for your help in anticipation.


I think you can follow the same APM instructions on the Pixhawk, APM’s outputs 1 to 8 are the same as the Pixhawk’s Main out 1 to 8.

I have not flown a Pixhawk on a helicopter yet, but I have used the PX4. It does work fine, and you do plug the ESC into Ch8. No reason the Pixhawk should be any different.

Dear all, I am absolutely intrigued about this AP on a Blade 450. I am inexperience with most of the terminology. However I am pretty good following diagrams. I have seen lot of good info about how to install this AP on Electric 450 but all call for 8 channel control. I have a DX6i and I am wondering if the AP can be controlled with only 6 channels. Thanks in advance for taking your time to answer this post.

You pretty much MUST use 8 channels to control a helicopter. There are plenty of affordable 8 channel radios available. Check out the FrSky Taranis.

Hello this is my first post on the trad heli forum. I have an opportunity to buy a Vibe 90 in good shape and for a very good price. I was wondering if it might be a good platform for Pixhawk size wise? Would motor vibration be an issue? What about keeping it as a flybar vs flybarless conversion? I see that most people into ardupilot are interested in autonomous missions but my interest is in using pixhawk as a FBL controller with programming flexibility and processing horsepower. It is hard to find any information at all indicating how pixhawk would perform as a FBL for flying hands on in rate mode and doing the normal acro type hobby flying, so I would appreciate input from anyone with hands on experience who can comment on how the hardware could be expected to perform in that role in comparison to any modern high end flybarless controller such as a brain or skookum etc. The reason for this rather than just using an off the shelf FBL is I am interested in using the capabilities of pixhawk to enforce a restricted practice area including an altitude floor automatically preventing the heli from crashing and also protecting the pilot and any bystanders when mistakes are made at the controls.

I have used pixhawk in flybar less as well as flybarred system with great results. Once you are done installing pixhawk and tuning it, basically you bird become an autonomous flying machine. This will take some effort in out part. If all you want is flybarless system, I strongly suggest that you not use pixhawk, although it will do the job. The reason is it is more complicated and time consuming then buying a decent flybarless controller. If you want to fly your heli in altitude hold or position hold mode then it is a great choice. Vibration can be taken care of, by using a vibration isolation system. I had a 50 size heli with a lot of vibration, later I found that the main rotor rod of bent. After I replaced it, all was good.

I would agree with @Sunit_Pal regarding the Pixhawk with the current ArduCopter firmware does NOT support RC flying the way you intend to fly (acrobatics) especially without a flybar. I agree that the pixhawk offers some great safety nets that would keep you out of trouble but the flying qualities for a flybarless heli with the Pixhawk are no where near that of a 3 axis gyro system. The issue comes down to the ability to tune the PID controller with helicopters is limited because they are more sensitive to aircraft oscillations feeding back into the servos causing a resonance (oscillations that can damage your heli if they get too bad). This is different from isolating the pixhawk from vibrations. Even if you minimize vibrations on the Pixhawk with vibration dampeners, you will still encounter the limitation with the PID tuning. Hopefully in a future release of the Trad Heli firmware, they will add a notch filter that will help prevent these oscillations from getting back into the servos and cure the problem. Read my post on Techniqe to expand roll and pitch rate pid gains without instabilities for more information. I have successfully integrated notch filters into the PID controller and have achieved flying qualities in acro mode that are better than a flybarred heli. I can’t compare it to a 3 axis gyro system cause I’ve never flown a heli with one.
I hate to turn you away from the Pixhawk but until the developers implement this fix, you’ll be wasting your time and will be very frustrated. Now many of the Pixhawk users have integrated a 3 axis flybarless gyro with the pixhawk with some success. I think it will still achieve your goal of having the safety net with the pixhawk but the gyro is stabilizing the heli. There are a few discussions that go into detail on how to integrate the 3 axis system with the Pixhawk.
Good Luck,

1 Like