450 copterx 450 tail problem

[tricky1400]

hi i am new forum member , been getting on well with my copterx recently but had a bit of a problem over the weekend .

i was flying / hovering not too high when all of a sudden the heli started to spin to the left so i brought it down quick as possible , maybe too quickly i dont know , i suspected that the heavy landing would have caused the front drive gear to be damaged so i put a new set of gears in the front and checked out the rear gears which seemed fine , no damage .

thing is that when i went out again to test it i found that it was still spinning to the left as soon as the heli went light ready for lift off and although i put a lot of right rudder in the heli still turned to the left .

anybody got any ideas what i could try next , both of the gear sets front and rear are good , i have made no adjustments to the heli since it was flying fine .

thanks for any help / suggestions

 

[breeze400]

Check your placement of your tail servo. It might of moved by you picking it up by the tail. Or the control rod might have got bent. That happened to me on my last crash.

 

[Tony]

From what you are saying, with no rudder movement even with input, I'm thinking either the gyro or servo is bad. Will the servo move when it's on the ground so you can see it? i would double check all servos on the heli. If you find that the rudder doesn't work, plug another known working servo into the gyro and test it. If that servo doesn't work, then plug the good servo into the Rx directly. If you still don't get any movement, you may have a bad rudder port on the Rx. But, start by checking with the heli sitting on the table.

 

[Lee]

As Breeze said, Check mechanical things first. Does the servo look like its moved or loose? With the servo at 90 are the tail blades even?
If everything is mechanically right, then move onto what Tony said.

 

[tricky1400]

thanks for all of your replies

when it happened i checked the rudder and noticed that when on the ground with the main blades not spinning i could put some left input in to the rudder and i noticed the movement but when i put right input in there was hardly any movement at all .

since owning the heli i have never been happy with the tail / rudder and always sort of suspected something maybe wrong but i was not sure what .

looking at the mechanical parts they all seem to be ok with no obvious signs that something has broken on them or that they are bent .

when setting up my rudder im not really sure how i should do this , i have my giro on different settings so i can switch from HH to rate mode , should the rudder slider always start dead central on the slider when im in both HH and rate mode ?

and should it always return to dead central after it has made a input ?

before this happened i did notice that the slider tends to creep over to the right end side( looking from behind the heli ) as i am flying the heli , is this normal ?

im going to set it up on the test bed i have made for it today to see if i can find the problem so will report back later with anything that i find , only problem i have is i dont have any spare servos or giro to try on it if i cant sort out the mechanical side !

thanks again

Rich

 

[breeze400]

Thats because of the gyro. What you have to do is set the heli on the bench or just hole it. Take the tail and do some sudden motions to the right and left while holding the front steady. You should see motion in the rudder. if you do not then something is going roung witrh the gyro. If it moves in the direction that it should, I would look for something machanical.ither the front tailshaft gears or the rear gears may be striped or maybe A pin fell out of there somewhere something like that. make shure the main gear is working properly and both gears are turning when fired up. It could be anything. Oh and make sure when you are checking the gyro that your motor is unpluged. We don't need any injuries! LOL

 

[Lee]

Ok lets say everything mechanical, is fine. Your next step, start from scratch.
There are some great videos Tony made online to help with tail set up.
But to give you a quick start guide.
(1)Plug the servo straight into the rudd port on your RX (no gyro) and adjust everything to get 90 degrees on the servo arm and tail blade pitch slider in the middle of the tail shaft.
(2) Follow you gyro and TX instructions to set up for Rate mode and Head hold. And plug everything back in the way it should be.
(3) In RATE mode get the heli light on the skids, don't fly. It will want to turn in one direction, use the rudder stick to hold it straight. remember how much rudder you needed to hold it straight. Power down and then looking at the tail servo, move the stick to the amount you were holding. Slide the servo on the boom to the direction the servo arm was pointing.
What you are doing is trying to eliminate the need for rudd stick input while flying. This could take a few trys. Oh and do it were theres no wind
Once thats done, change to Head Hold.
you will find the servo will move to one side or the other (servo creep) use the subtrim menu in your TX to eliminate this creep by adding or subtracting trim till it stops the servo moving.
In HH add gain in your gain channel till you see the heli tail start to twitch, then back off a couple of percent and you are done.
This is a rough idea. Things maybe different for your Radio servo gyro. But its a start.
Hope it helps

 

[Tony]

I agree with everything Lee said, except the servo creep. In HH mode, the gyro is trying to hold the helicopter in one position, or heading. if the helicopter is moved ever so slightly, the gyro will give input to the rudder servo until that helicopter is back to the same heading. That is why you should always plug the battery in where you are going to be flying. Not necessary but helps. Just remember, the gyro in HH mode is locked onto one heading. and it will do everything it can to stay at that heading.

to recap, in rate mode, the servo will always go back to center when you let go of the stick. But HH mode it will creep to one side or the other. From what I have read on your last post, you need to adjust your endpoints. Make sure your servo has not moved at all. When the servo is centered in rate mode, you should have a slight bit of right rudder in the tail. Only a little bit though. Hope this helps.

 

[tricky1400]

wow !!!! this is all so confusing to me !

i am going to have to print this all out and read it over and over again until it sinks in .

i never gave it a thought that when i am connecting the battery in HH mode that i should be pointing the heli in the direction i intend to fly , i just assumed that i had to connect the battery and keep the heli still while the gyro did its job and when the light went solid it was ready to fly .

im off to work soon as i work nights but i will be having a look at everything again tomo with batteries fully charged and all of your replies printed out to help me .

i really like the copterx and was getting on so well with it but things happening like this really dent my confidence and spoils the enjoyment i get from flying it .

i will post again as soon as i have any further news , thanks again to all of you who have posted help for me , its really much appreciated .

 

[Lee]

Dude if you are working on it tomorrow, let me know. I'm online nearly all day, dont start work until December So we can work on this together if you want.

 

[ARM_Coder]

I usually nail down tail problems in the following order:

1) Power down the heli
2) Disconnect the link rod from the rudder servo horn.
3) Move the rod by hand, the tail mechanism should move smoothly all the way in and out, until reaching the mechanical limits.
4) Move the servo horn by hand (gently!) and see whether it's moving smoothly and its range of motion is enough to cover the travel you've seen in step 3.

This should sort out the mechanical problems.

5) Set rudder trim to center in the TX.
6) Set rudder subtrim to zero in the TX.
(edit) If you changed the trim or subtrim, it may be recommended to redo the radio binding to ensure the gyro will initialize correctly on power-up.
7) Power up the heli (it's recommended to unplug the motor cables before to avoid the risk of accidental spool-ups)
8) Adjust the gyro gain to a value that will put it into NORMAL (not HH) mode.
9) If needed, take out the servo horn and reinsert it to obtain 90 degrees (or close to) angle with the rod. Now the servo horn is centered.
10) Reconnect the link rod to the rudder servo horn.
11) Adjust the servo position (slide it along the boom) so the tail mechanism is centered on the tail rotor shaft.
12) Adjust the gyro limits, so stick inputs will make the tail mechanism travel the maximum possible before hitting the mechanical end points.
13) Check reverse for servo and gyro.
14) Set the gyro's gain to HH mode. Try a value you are familiar with, if too low the tail won't hold, if too high the tail will shake (wag) during flight.
15) To test, take off slowly, testing the rudder response with the skids still light on the ground.

Phew! I hope it helps!

Cheers!