I now have 2.8.1 code working for TradHelis. For anybody who has not been following along, this now brings attitude rate control to TradHelis for the first time. When combined with Leonard and Randy's Earth to Body frame rate rotation algorithm, the performance is excellent! Please watch this video, and remember this is a flybarless 450 heli. Normally these fly like a rabid squirrel!


Sorry about the shakiness and my daughter's commentary, she had to come out with mommy and daddy. ;)

It is now really easy to fly around very sporty, yet precisely even at high speeds. It has no nasty tendencies. There are a few spots where I zoomed upward, but that was completely intentional.

The only weakness I can see is an occaisional "bobble" of the pitch axis at high speeds, but this is actually present with many professional FBL controllers. I may be able to tune it out yet.

There is still ongoing work, but it's looking really promising!


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I've just come down from the loft with the remains of a blade400. I will get it flying like the rabid squirrel that it is then steal the APM 1 off the tri. 

I need more APM's!

Just test flew the latest.  It's so good I want to cry.  I can't wait for you guys to try it!  

I even got rid of the tail waggle I always had!

Daddy it`s flying away!   :)   is this the new voice for the mission planner? 

hehehe nice flight Robert. 

Looks great.  Is it recommend to run a flybarless setup now?

Josh, I'm not sure yet.  I find this is flying great, but I don't know if it would be better with a flybar or not.  I've never had a 450 flybarred.  It's not nearly as stable as my flybar 600 but then... it's a 600.

I'm building up a FBL 600, and I will probably also test it with a FB head to compare.  But I don't know when all that will happen as it's getting pretty cold up here!

In testing, I've had some evidence to support the theory that the much stronger filter I'm running in the MPU6000 will make this much more resistant to "leans".  I can hear a noise that makes me suspect a bearing is going on the 450, it's got that slight buzz to it.  But I had no problems with the MPU filtering at 10Hz.  Last night, I changed it back to the standard 98Hz filter, and I instantly had about 20° "leans"!  I put the filter back at 10Hz, and the leans were gone.

I plan to release the next revision with the default TradHeli filtering rate at 10Hz.  This is obviously a HUGE deal if we've solved this problem!

OK, I thought I read somewhere that you can only use acro mode with a flybarless setup, so I wasn't sure if that make it more stable.

I've been slacking on doing any testing on my Trex 500, and I was going to order a flybarless head from HK, but since that's going to take a while to ship, I might as well test it with and without the flybar. 

Please post your PID setting as what you have now.

Thx, Brian

Thanks a lot Robert, for your efforts to get to this point....

Looks and sounds exiting, also your new 10Hz filter to reduce or eliminate the leans is the way to go.

We all experienced more or less this leans on heli’s.

I’m looking forward to try and fly my T-Rex 450 and now my new 600 with the great Arducopter 2.8.1  

Actually, I think since I posted last, I have done more testing that shows the "leans" is significantly helped by the new filter.  I had my heli flying fairly well with the 10Hz filter, and then I set it back to the current level of 98Hz.  The heli flew crazy bad.  I tore it apart and found two bearings were done. (and these were genuine Align bearings too, they're junk).  

The 10Hz filter helps a lot, but can't completely eliminate the problem.  I still wish we had some way to detect the problem to warn about it.

Yes lots of junk are sold nowadays, to keep the so called economy running (controlled obsolescence)...

keeps you buying...


If the 10Hz filter reduces the leans to a great deal, then it’s still a great achievement and it will reduce the risk of a crash in case a bearing goes bad during flight.  To implement a warning might be tricky at first thought.


I just was flying the 450 today, switching to ALTHold and buzzing around. While hovering, the heli was stable like a rock, could leave it for a min without touching the controls.  But when speeding around, I experienced some leans to the right and pitching up, when slowing down to a gentle speed or hover, the leans disappeared in a few seconds.


I’m really interested to see how your new 10Hz filter performs with this.

I’m sure it will.


I don’t know if it’s an advantage to have the filter frequency adjustable by a parameter to fit different vibrational footprints.

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