500 Trex 500 Tail bobbing issues

[Westy]

Hey Guys .... I got a mate with a Trex 500 Pro (DFC) running Helicommand HC-3Fx Controller.

Have played with the D GAin and makes no difference.....

Tail is bobbing up and down like the Elevator function of the Helicommand is over compensating......

Anyone had this issue? or sorted it?

Cheers

 

[Tony]

Sounds like either the elevator gain is too high, or there is slop in the head and he needs to raise the head speed.

 

[Westy]

Head speed .... this things is cranking at 90% throttle...... tried experimenting with D gain (Elevator) makes no difference high or low to the performance and does not change anything.

 

[Tony]

check for slop in the head, swash and servos. That is the only other thing that I can think of.

 

[Graham Lawrie]

I had a similar thing on my 600. It was a combination of head slop and main shaft I think. I will look back and see if it was anything else and post up

 

[pvolcko]

Are you sure "D" gain is a generalized elevator gain? I'm not familiar with HC setup, but when it comes to PID controls D is a derivative gain, which is what controls how well it dampens approach to the target point. Just want to make sure you are adjusting what you think you are adjusting.

If D is a derivative/dampening gain and you feel you have it high enough to be producing results, perhaps trying lowering P gain a bit. IT is possible P gain is too high resulting in it overpowering D gain's ability to dampen the response effectively.

 

[Tony]

Are you sure "D" gain is a generalized elevator gain? I'm not familiar with HC setup, but when it comes to PID controls D is a derivative gain, which is what controls how well it dampens approach to the target point. Just want to make sure you are adjusting what you think you are adjusting.

If D is a derivative/dampening gain and you feel you have it high enough to be producing results, perhaps trying lowering P gain a bit. IT is possible P gain is too high resulting in it overpowering D gain's ability to dampen the response effectively.

Where in the hell did I put my ban button... There were WAY TOO MANY school words used in that post!!!

 

[Stambo]

Where in the hell did I put my ban button... There were WAY TOO MANY school words used in that post!!!

LOL I read that post 3 times and I still don't understand it fully.
Everything after "Are you sure" is still a little vague.

 

[cml001]

Lol... Wow

 

[Ken Jackson]

Hey Paul I'm with you on the PID loops.

Ken

- - - Updated - - -

However I doubt anyone has access to the PID algorithium, only the gain input into the formula.

Haha

 

[murankar]

My fbl has the pid settings available for adjustment. They can really wake things up If set Right for your flying style.

Sent from my LG-E980 using Forum Runner

 

[pvolcko]

Sorry. Hopefully the terms make sense for Westy as he's looking at the adjustments available.

Ikon has similar adjustments (PID gains) in advanced mode of the setup software.

In my alternate alternate life I'm a controls engineer. I can rant for a long time on this stuff.

 

[cml001]

Not familiar with hc gyros at all.. But today I had a tail bounce issue with my AR7200BX... I had to drop cyclic gain and "pitch up compensation" to get mine right... Does the hc have a parameter similar? May try that if it does...

 

[Tony]

I understand every bit of it, just joshing you around a bit

 

[Ken Jackson]

12345

 

[Tony]

 

[pvolcko]

I'm a master thread jacker.