Hey all...I've been going thru every post in this forum and I have to say...we've all had the exact same problems. except for the smart vets who know how to take their time and not break anything. thanks to all for the good advise and free flowing info. Anyway...i've got my CX pretty dialed in, except it wont stay in perfect balanced hover...it likes to fly in a four foot circle in reverse, going clockwise...basically like a reverse donut in a car. I've got all rotation trims max'd out..transmitter and pot. any thoughts? i can't tell if its one rotor going faster than another or if its a pitch and yaw thing. ALSO..anyone know where i might find a diagram of the physics involved here...if I can get a grasp on the principles and what parts on the heli do what jobs..i might be able to solve future problems. thanks in advance from a serious NOOB. quattro

Hi,
If you haven't done so already Make sure everything is straight-inner, outer shaft, flybar, blades are balanced, there is no flashing on any of the plastic linkage balls, or linkage connectors, Is your swashplate level? Is your heli level when you pick it up?. I am new at this, and probably missed some diagnoses, but the latter has helped me fix some problems that I have had. Someone on here will have the solution, they always do!!! Good Luck!!!

Or maybe one of your motors is faulty?

I would recheck how level your swashplate is. Then I would set the pot in the center and center your transmitter trims. You should never have to max any of those out. Once you have them centered then adjust your pot until your helicopter doesn't rotate.

thanks, all, for the info. i've checked all that stuff over and over...except, the swashplate. I checked it and I know what level is, but how does one level something 1/2" wide? can i assume it should be parallel to the rest of the system and perpendicular to the shaft? should i use a square? It was suggested in another forum to remove the rudder spring from the controls. i did and it solves the problem in a "back door" kinda way.

quattro,

Have you tried trimming that problem out?

Start by using forward elevator trim to stop the backwards motion. If you max that out then you need to level the swahplate.

Guys.............are you sure he isn't describing TBE? If the swash if off..the heli will only travel in one direction, the direction the swash is aimed. TBE- Toilet Bowl Effect is caused by either binding in the flybar or the shafts. Heli will make slow circular motions just as you are describing. The most common problem I have had experience with is a bent or binding flybar causing it. Second is binding in either of the shafts. Ya gotta go thru all of it one step at a time and find where your problem lies..... it isn't your swashplate. Start with the flybar and make sure it isn't bent and moves freely. If you still have it check the collar just below the swashplate, sometimes you can get it too tight and cause binding. You should be able to just barely move the shafts by pulling lightly on the head, 1mm of play is plenty. Check the inner and outer shaft for straightness, and if there is anything causing them to bind. Lastly I would suspect one or other of the motors, but very doubtful.
It is either a bent or binding flybar or one of the shafts, and remember, when checking that flybar don't forget to check the tracking on the upper blades. If they are out of cahoots that will cause issues too.Let us know what ya find out.


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

Does your heli back around the circle or does the tail always point in the same direction while going around. If the tail leads the heli around the circle then you have to trim out the reverse and the rudder directions. If the tail aleays points the same direction around the circle that is toilet bowl effect TBE and is caused by the flybar being bent or not moving properly.

so far i've replaced the following parts and they were not all broken when upgraded. [upper rotor head(cnc) and inner shaft, outer shaft with gear, blades, lower rotor assembly(cnc). Neither new or old shafts were/are bent. All and all, removing the rudder spring on the controls is the only thing that has worked and i'm finally flying in a hover without hearing $$$$...but it shouldn't need a workaround. thanks for the info so far.
quiattro

ohh...your toilet bowl theory sums up my problem...see my diagram..thats whats happens...wassup widat?

Mild TBE like that described can also be caused by blade tracking being off. More so upper tracking than lower tracking. If the blades are balanced and tracking correctly and you still have TBE then look to the flybar. If the flybar is free and clear with no bind what so ever, then progress to shafts etc. etc.

I still think he has a yaw problem (CW) combined with backwards movement caused by the elevator.

He corrected, but did not fix the yaw, by doing the Tx rudder mod.

To me this indicates a binding or motor issue causing yaw. Flying like that and the rudder stick held to the side will surely cause more problems and probably burn out a motor faster.
Unless I'm misreading his issues.

Your diagram shows the heli backing around in a clockwise circle. That is not TBE.

I agree with Wolf,

You have a compound problem, easily corrected.

First; don't worry about bubbling the swash perfectly level. Perfectly level doesn't always equate to perfect flight characteristics.
Adjusting the elevator servo arm out a couple of turns or so will fix the backwards problem (if Your battery is seated properly all the way forward and You are putting the battery in the same way each time).

Then, adjust the pot. If You can't get it to stop and the pot's maxed, then replace the motor; simple as that.

Simple as that, if everything else isn't contributing to creating alot more resistance to that particular shaft; end play, gear mesh, etc.

Gary.

Guys, yes it is a form of TBE, the swirling pattern it's flying in is a direct cause of TBE. Trust me. I had it this morning. Put on some new blades and sure enough around and around she went, combination of blade tracking and sticky flybar. Now for the remainder of the problem I would say it is just a matter of trim, maybe some binding issues however the bulk of it to me still sounds like TBE like I was experiencing this morning.
The backward flight is most likely a balance issue, COG messed up, or it could be a trim issue.

I guess the form We're thinking is when the heli moves in a circle, the nose of the heli follows the tail. That wouldn't be a flybar problem, I wouldn't think.


My opinion of 'classic' TBE would be where You have it flying in a circle but with the nose not following the tail; it starts out small and gets larger and larger; kinda like a flushing turd fighting for its life or something. Then flybar is the first to check and blade tracking.


Gary (the x-mas poo)