450 My heli bounces lots it bobs up and down even without touching the throttle

[orbi]

I have 2 450 helis one is a Pro and one a Sport. they both bob up and down all the time its such a ball ache as they are really fine tuned on the throttle, I mean I only have to touch the throttle a teeny weeny bit and theyre away. I have set the throttle for 60-70% position 2 thru 4 so that my input is nt too severe and the motor seems constant and even. My throttle line looks more horizontal I have about 5 deg of positive pitch at midstick as I am just in the hovering stages

any ideas guys thanks Paul

 

[Tony]

You really need to set it up with 0º pitch at mid stick with the same pitch both positive and negative.

 

[pvolcko]

I agree with Tony on getting it setup right. You should have 0 deg at midstick and equal deg pos and neg at the max and min stick positions.

Once you have that set, some ideas to make it less jumpy:

1) Lower your 60-70 throttle from positions 2-4 down to 50-60. This will lower the headspeed in this range and in turn make it less responsive to collective and cyclic response.
2) If you don't want to loose cyclic response you can, instead of #1, try flattening your pitch curve from the 2-4 positions. For example, if you're running a normal mode curve of 40-45-50-75-100, you can try 40-45-50-65-100. This will make the collective a bit less responsive in the 50%-75% stick position range.

You do not want to take these measures too far. Running too low a headspeed/throttle will put strain on your motor and ESC as it can be running outside it's most efficient range. It can also result in "wobbles" while hovering if it gets too low. And screwing with the pitch curve too much can lead to you not having the response you need in an "emergency" when you want to climb out of trouble. Especially when coupled with a low headspeed, it will bog out very easily on an aggressive positive pitch change.

Hopefully these measures are temporary while you get used to hovering and through some beginning forward flight. But try to get back to more standard curves on pitch and higher throttle as soon as you can. You don't want to become dependent on the more docile setup.

 

[orbi]

Thanks for that... I have just tried the 0 pitch at mid stick and played around with head speed but its just the same it bobs up and down from 4ft to the ground. Ive noticed another problem ....the tail is drifting way to the right. when i get a full tail on and steady it holds for like 3 seconds and then slowly drifts right. ive tried adjusting the linkage rod but it doesent make a heap of difference there. is it the gyro sens. ive moved that from 70/30 to 75%/25 and its just the same should I go like 80/20. the heli is tracked up well and runs like a dream so im kinda stuck

- - - Updated - - -

oh and its real calm here too so its not a wind prob.

 

[pvolcko]

I'm not sure what you mean by 70/30, 75/25/ 80/20 on the tail gyro.

If those are gyro gain settings in your Tx... what gyro are you running and what Tx? Different setups of these will control the range you need to set things in to get into heading hold vs rate mode on the gyro.

It sounds like you are trying to fly the tail gyro in rate mode instead of heading hold mode. Usually the tail mode is controlled with the amount of gyro gain you have dialed in for in on the Tx. On my 7200bx and DX7S, for instance, If I run the tail gyro setting at -100 through 0 then it will be in rate mode with higher negative translating into higher gain. 0-100% will put it in heading hold mode, again higher values for higher gain.

If those were gyro gain settings, what switch is controlling which one of them is active at a given time? The same as you flight mode switch? Personally I'd put the gyro gain on a different switch than flight mode. I use the rudder D/R switch, I think. Normal and idle up flying I put it on the heading hold setting. I only use the rate mode setting to "reset" the gyro and center the tail slider before spooling up for a flight.

Your fix may be as simple as swapping the 70 and 30 to make sure the heading hold setting (probably the 70) is in use for normal flight mode or whatever your default switch position is.

 

[Tony]

Can you post a picture of your helicopter ready to fly, or even better, a video of it flying?

 

[pvolcko]

And maybe run through your Tx settings.

 

[orbi]

ok guys thanks ... I am using the gyro/flap switch for rate mode. when I adjust the 70/30 on settings the light on gyro will auto switch from green to red at the 50/50 point. green is HH and red is rate mode. im using spektrum 6xi radio. if i can get over this bobbing and keep the tail from drifting right then I will have a superb bird. with the tail i have the srvo mounted now on the boom ( i just hated it buried in the frame) i can now adjust the servo real quick , I have tried it always in and out but it dont semm to make a whole lot of difference, the tail just as always drifts right slow but sure. am i being over fussy ? I am busy at the mo guys but will try and get a video of the bobbing. etc.


again many thanks to you!!! Paul

 

[pvolcko]

Okay, sounds like your gyro gains are reasonable and that it is in heading hold and still drifting. It could be picking up more vibration now that it is mounted on the tail, which can cause drifting and other odd behaviors.

Also make sure you do not have any rudder trim set on the Tx. It almost sounds like you have accidentally clicked in a couple points of it. Easy to bump it by accident. I make it a habit of checking the bar displays to make sure rudder has no trim dialed in (and the others in my case, since I'm on FBL). IF no trim is dialed in, then also check the "subtrim" section under servo setup, make sure nothing is there for rudder either unless your gyro setup specifically allowed for it. If it does, then you may want to go through setup again and dial in a little bit more subtrim to eliminate the drift. In general with heading hold mode gyros you want no trim and no subtrim since the gyro will interpret that as a stick input. Some gyros and FBL controllers do allow Tx subtrim to be used, but you have to check the instructions for your specific gyro.

 

[Tony]

Please post a picture or video of the head, and such so that we can see it. This could be really simple, or indepth. A picture will help out tons in this issue. I have an idea of what it is, but need to see it first.

 

[murankar]

Which gyro are you using for these birds?

If you are using subtrim for the tail you will need to reboot the gyro or it will see it as stick input. Next, if you are using subtrim to get the tail to hold center then you will be able to adjust that out with the linkage rod. It will take a lot of twisting to get it to the correct length. Instead of going up in gyro sense I would try and start over at 65 and see what happens, usually you will see a lot of wag in thail when you go to high in gain. You will want to get rid of that drift before you work on the sensitivity of the gyro. Solve one problem before workiing on another. As for the Bobing up and down do as Tony said get 0 degrees at mid stick while in ID1. Make sure you have both blades set to 0 degrees and then check your high then your low, those should be around 10 degrees + and -. Now for the bobing, whats your Head speed? Mine was two low and it introduced a bobing and drifting that was to hard to control, this could be the reason for the drift in the tail also.

 

[orbi]

The tail drift is sorted. I changed the head and immediately saw less vibration, I took every nut and bolt off and redone em with thread lock making sure I had it tight. also the bearings and washers in the rotor clamps. I found out there should be 2 very thin washers to take out any play in there, they are not in the Align manuals. for my Pro 450.
When I put my last head on, I did not strip it down for locktite and got vibrations I reckon. The servo mounted on the boom is adding to the drift especially with the vibrations,, possibly less noticable on a bigger heli I guess. The heli does bob still, but nowhere near as bad.
My subtrims etc for the rudder have not been touched. zero. gyro is 75/25 in HH
All in all my Pro and my Sport are now working the same. I use the Sport for training now as it is easier to repair in minor crashes the belt drive is way easier to sort out,
Wondering though why dont they make ali gears or strong gears INSIDE the frame where its a pain to access and use a more fragile one where it can be easily replaced where it is accessible. That way your always replacing the weakest link where its easily done.


Thanks again guys for all your input youve been really helpful.

 

[murankar]

I would really check your head speed. Make sure you are not to low on it.

Glad to see that you are sorting everything out. Just remember to change one thing at a time and test it.