Im kinda new to the hobby, and im in over my head. I just installed a aluminum head , outer shaft ,and swash on my CX2. I powered it up with body off, to make ajustments to swash and once it took off it started shaking violently side to side. It was 2ft off the ground. I did notice at a little less1/4 throttle only lower blades got power then added more throttle and top blades started spinning. Is this normal? Anyway,I thinking its maybe the flybar ( stock )causing the shaking? Should i put the body on when testing and keep taking off to adjust swash? Its also seemed to nose down when taking off as well. Thanks in advance for the help

Okay, well first, welcome to the forum!

Second, you have WAY too much going on there. The rule of thumb for upgrades and mods is to only do one at a time. That way, if something goes wrong, you know exactly wheer to look.

Third, what do you mean by shaking side to side? Give us a better description, or, better yet, a video clip if you are able.

Fourth, you can fly around just fine with your canopy off. I do this all of the time when I am setting up, tweaking settings, etc. I only put the canopy back on when everyhing is dialed-in.

Fifth, any unbalance from fore to aft is most likely caused by improper positioning of your LiPo pack. Think about what you just did. You just added a bunch of weight.. to where? The front of the Heli! You will want to counteract this imbalance in the COG by moving your LiPo pack aft towards the tail.

Go back to stock and see what happens. If the shaking is gone, then you know it was one of the upgrades. Put one thing on at a time and put her in the air again. Come back with specific questions and you will get all the help you need. There are lots of experienced pilots on this forum.

First thing; Make sure the flybar isn't binding; it needs to bounce up and down with complete freedom.

I bet it's as simple as the upper blade tracking is WAY off. If You replaced the upper head, then You almost always need to adjust the link from the upper blade to the head until the blades at the top stop vibrating. Rev it up and see that the tips of the outer blades track on or near the same line. If not; it'll cause the problems You're describing. Turn the little ball link one full turn either direction and see if it gets better or worse. If better, than adjust the same direction by half turns until it's pretty much on track. If worse, go back the other direction 2 turns, and half turns after that.

Gary

I agree with Bry and goldslinger.

The wobble or shaking is probably caused by an imbalance in the flybar or shafts.
I would take the inner shaft and upper head off the heli and spin up the lower rotor only. Check for a wobble or shake by looking down on it from above. If it does not spin true then the problem is with the lower assembly/outer shaft.
If it is good then put the inner shaft/upper head back on and spin it only, check for wobble again.
That should help pinpoint the problem.

Also, in moving to the aluminum lower and swash, your swahplate is probably way out of "level", causing directional movement.
You need to level it by lenghtening or shortening the pushrods (linkage from servo arms to swash).
You can eyeball it first by trying to make it level with the rotational plane of the lower blades.
Then when you are able to hover again, if you have forward motion, and your COG is OK, the LEFT pushrod needs to be shortened.
Backwards movement = Left pushrod needs to be lengthened.
If the heli moves/banks to the left then the RIGHT pushrod needs to be shortened. And movement to the right = Right pushrod needs to be lengthened.

I got to thinking;

and I too get to shaking when flying, after all the expensive mods. I shake because I don't want to crash !

I tried the adjusting the flybar and changing it but CX still wobbling in air. Gonna rip her down and start over.

Once again, if you can be more specific about this "wobbling" or post a video, you will probably get more focused advice.

If You adjusted the tracking; check the little inscribed number (1 through 4) on the hub of the blades; if they don't match, then You definately need to balance them; night and day difference.

All I can think of right now.

I have found that blades with matching numbers still need to be balanced.

This one is easy to fix. Put the body back on your heli and the problem will go away I tried to fly my CX2 with the body off and it did exactly what you are talking about. I think the shaking side to side has something to do with the gyro trying to hold a direction and when it trys to make a slight change it goes to far because of lack of wind resistance because the body is not installed. Anybody with a CX2 should be able to replicate the problem. Just take the body off your heli and try to fly it

I fly my cx2 with the body off all the time and it flys the same either way. Actually I think it flys just alittle better without the body inside.

Hmmmm thats interesting i figured they would all go crazy with no body on them. I dont doubt you though because it seems like every heli is its own beast. My CX2 goes crazy if i try to fly it with the body off. It jerks from side to side exactly like stiracer describes. My heli is sitting at work right now but if I have a few minutes I will go grab it and make a movie of it going crazy. If some do it and some dont could it be the gain setting on the gyro causing it to happen ? I always thought it would fly fine with no body until one day a friend ask me if it could fly with no body. The heli was tuned almost perfect. I took the body off and tried to fly it and it went out of control and wasnt flyable at all.

That is a new one to me. My CX2 flys equally with or without the body on. If anything with a full body on the wash from the rotors actually makes the heli MORE unstable. I only fly with the front canopy on and have the boomtown skids and tail. Much more responsive and actually flys better. The wash off the rear body half and the wings creates a bigger hole under the heli and makes the tail much less responsive. Just my opinion but I have flown both ways and find the tail boom a much better flight experience.


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Of all the things I ever lost....................................... I miss my mind the most!

Looks like im missing the step washer on the outer shaft. COuld that be the cause of my wobbling side to side? Going to get one Monday afternoon and give it a try. I will let you know what happens. If not i will need to acquire a video camera to post a vid.Thanks for replies

If the step washer is missing then you can have binding in the shaft and the rotor speed will not be constant and can make it fly poorly, very poorly.

Good detective work stir! Me thinks you have found the culprit.


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Of all the things I ever lost....................................... I miss my mind the most!

I went and grabbed my heli and made the video. You guys can decide for yourselves what is making it go crazy like it does with the body off. http://www.rcuvideos.com/item/8F1KQZ8MCLQ7F4K6
I hope that link to the movie works its my first time posting one on RCU.

I bet if you had a CF tailboom, or put the stock tail back on, it wouldn't do that. Adds weight, stability and levels COG.

And you should get a CF boom if you don't have it already.

I am happy with the police body and as far as upgrades go my CX2 isnt getting anymore of them. I am waiting on the Blade 400. As long as it has the stock tail on it it doesnt get wacked out when it is in the air. Why taking it off makes that happen I have no idea. If I am understading the first post right though it sounds like it is exactly the same problem.

My best guess would be that the gyro is set to compensate for yaw taking into account the weight of the tail. Without the weight back there it overcompensates and twitches. Turning the motor gain pot down might correct that.

Hance,
Are you at significant altitude by any chance? I'm curious whether the Blade 400 will do well up here.

I live at about 5600 feet. The town where I work is about 3500 feet so I have a pretty large elevation range that I can test the heli. I get down to your neck of the woods once a year usually. Flew out of Buena Vista to the top of Mt. Princeton in a real heli for work a couple of years ago. When the pilot lands at the airport to pick you up and asks how much you weigh then says " I think we will be OK" it doesnt do much to boost your confidense.

I think i am going to play around with the gain on the gyro and see if i can trim the death wobbles out of the heli with that. I will report back once I figure something out.

Yeah, the top of Princeton has to be around 14,000 ft. It's got to be tough generating lift up there.

I'm concerned about the 400"s ability to lift here at 8,000 ft; even the CX2 struggles with shorter flight times, heat and loss of lift when the battery drops down to 7.4-7.6 volts.

Ok i backed the gain off on the gyro and the death wobble what ever you want to call it is gone. Keeping track of what way the heli is facing is a lot more interesting with no body on it though

Good ventilation, though.

THe video HANCE made is exactly what my CX2 does. I took her apart and i am missing the step washer thou. When i get the washer i will put my CX back tougether and see what happens with body on and off. If it does it with body off still but not with body on what should i do ? Adjust gain.