Pixhawk and Trex 450

ArduCopter Traditional Helicopter
1

I am going to put a pixhawk into an old trex 450 do a need to change the head to flybarless or will it be ok to test with the flybar

David Ardis

2

Sorry I don’t know the answer, but IIRC the old code for flybar had some bugs and Tridge eliminated all(?) of them. Try to contact Tridge or Rob_Lefebvre to get an answer.
On the other hand it is an old heli and trying it without blades should give you some clues.

3

Hi,

My TREX 450 had a flybar and it was working fine. The version of the firmware used in the video below was Copter 3.3.3.

I updated to v3.4.x firmware at the same time I converted it to FBL, and all our flybar helis currently runs v3.3.3, so I don’t know if the flybar setup still works with v3.4.x.

4

Thanks for the reply. Would you have any pictures of your build to give me some installation ideas.

5

I don’t have the pics right now, but I initially used Randy’s mounting brackets and that worked well.
http://www.japandrones.com/shopdetail/002005000003/002/X/page1/order/

Since I have to fly it in snow, I ended up putting Pixhawk and other components in a waterproof case and hanged it below the frame (directly under the main shaft) using a floating mount. I also use tall skids take from 500 size helis to gain more clearance from the ground.

Regardless of how you end up mounting it, you really need a good vibration isolation/dampening mechanism.

EDIT: Here’s a picture of the configuration that uses Randy’s mounting brackets. Please note that this was after I converted it to FBL (you can see the Futaba FBL controller mounted on the side of the frame). Also, the floating mount pictured here was inadequate in isolating vibration, but I don’t have the pics for the improved version…

TREX450.jpg1280×960 288 KB

6

Thanks

That’s Basically how i was going to do the install

7

Why do you need the CGY750? Connect everything directly to the Pixhawk!

8

Because with the Pixhawk you will hit instabilities (bad oscillations) before you can tune the PID gains to values comparable to a 3 axis FBL gyro.

9

Several reasons.

  1. As @bnsgeyer mentioned, FBL units tends to cope better with high vibrations and thus are much easier to get off the ground without meticulously balancing the heli or fine tuning the FC mount for vibration isolation and dampening.

  2. Our pilots are used to flying FBL and it’s easier for them in-terms of transitioning to the Pixhawk.

  3. We also have a fail-over system where the pilot can bypass the Pixhawk entirely and fly the heli manually in case EKF blows up or the unit browns out or some other nasty things happen.

1 Like
10

Will this work on a NITRO HELI?

11

Picture 202.jpg2448×3264 1.18 MB

12

We fly nitro helicopters too, with pretty much the same configuration as our electric heli’s. i.e. Pixhawk + external governor + FBL unit (or with flybar). However, it’s more difficult to set the headspeed and vibration isolation correctly compared to electric.

Also, shutting-off the engine after the flight can be tricky as you want the engine to keep idling while disarmed without engaging the clutch, but you can’t go lower than idling as there’s only one possible PWM value for disarmed state with the current firmware.

13

Do you happen to have the parameters file for the FBL setup to share?