I have an axe cp and as I increase throttle, the tail rotor is intermittent and the copter spins round and round. Some time the tail rotor pulsates and I can't seem to get it to stay straight. Any ideas as to the cause of this?

if you've got several hours on the unit, or you notice that the tail motor is getting warm, it just might need a new motor.

Some other things you could look at are is there a short or a loose connection or corrosion on some contact to the tail wire? Are you getting good signal? Ie the receiver wire in tact, the Tx has good batteries, the antenna is routed away from the motors ect.

Most likely though the motor is failing and needs to be replaced.

oh, I guess it could also too be the prop slipping. If you have gear drive make sure that your pinion is tight, that the gear is meshing properly and is attached to the prop so nothing is slipping. If you have a DD 3020 or 4530 system, make sure the prop is not slipping on the shaft.

DownForce it's most likely your 3-in-1. Sometimes they go out of adjustment for no apparent reason. I've heard that on cheaper electronics sometimes the values on the trim pots creep.

If I were you I'd start by adjusting your TR trim. Try and decrease it a little at a time then test the heli and see if it helped. If memory serves to decrease TR trim turn the trim pot clockwise. If you've found that the pulsing stopped, but now the tail has lost some authority you may also have to adjust Left/Right Bias pot. It's a pain in the butt. Three trim pots to dial in one tail is a bit ridiculous. Anyway if you can't get the tail dialed in your 3-in-1 may be faulty. This happened to me, but Hobbico sent me a new one under warranty. Hope this helps. Good luck!

I had the same problem, It's the board, call helimax and they will send you a new board.
They know the board is a week point and are handing them out like candy.

Is anyone actually useing the 4530 system.What size motor is that.I tried the 3020 and it doesn't have enough power to hold the tail under full collective.

Usually the DD tail system motor is a gws cn12 rxc (not the rlc) motor

This is kind of an old thread but...

I think my tail motor is just short of going out on me. Lately, the tail seems to be lagging and as I increase throttle the nose spins to the left (so that I'm looking at the left size of the Axe) and I have to increase right yaw input to compensate. It's trimmed fine and only does this on occasion, but does seem to be increasing in frequency. I can tell when it's low on batteries when the tail starts to wag; before this point, it just yaws right with no wagging when the tail lags. Other than in-flight observation, is there a way I can perhaps measure current or voltage of the tail motor to see whereabouts it is in its life cycle? I bought the Axe new I think back in late February or mid-March and have been flying it consistently 4 to 5 a week, 15 minutes each session.

McFlurry when the motor starts to go it will loose power. How much power does the tail motor have on a full charge with full right rudder? Also has the sound of the motor changed? If it sounds OK and still has power during full right rudder you may need to turn up the TR trim a bit. I'm not saying it's not your motor, but the 3-in-1 board does creep or at least mine did. I said it before and I'll say it again. Three adjustment pots for the tail is ridiculous.

Thanks for the response, Heliko. By your checklist everything seems okay (full-right rudder seems fine and motor sounds okay as far as I can tell). I'll trim it more to the right and hopefully that reduces it.

Not sure what you mean by this. Are you referring to the three adjustment screws on the 3-in-1? This is my first so I don't know what's standard and what's not. What's on a T-Rex, for example?

A Trex has a collective tail so the only adjustment is the pot on the gyro. I made the switch to a 240 on my Axe so I only have one pot too which makes trimming much easier.

Basically with three pots it's much harder to get a tail trimmed. With the 3-in-1 when the tail goes out of trim you have to try adjusting multiple pots to trim it out.

For example with the Axe you'll try turning up the TR trim first. That might work or it may cause the tail to get spuratic and start pulsing. If it starts pulsing you may have to turn the TR trim down and start messing with the Left/Right Bias. Then after that's all said and done the Gyro Gain may have to be adjusted as well. That's all I meant. It holds pretty good once it's trimmed, but what a PITA.

Speaking of the three adjustments, anybody know what the Left/right bias does and when to adjust it?

Not trying to hijack your thread, it just seemed like it was of the same problem/solution.

I'm not sure what it's supposed to do, but I can tell you what it does. It works kinda like the TR trim. When I was running the 3-in-1 I had some difficulty getting it dialed in. I couldn't get the tail to have enough power and to not pulse. So I turned up the TR trim as high as possible before it caused the pulsing then started to mess with the L/R Bias. It increased power to the tail without causing tail motor pulsing.

Here's what I'm thinking (hoping is more like it):

I'm flying in idle-up mode more often. Lately, especially when its nearly out of control, the collective is difficult to get exact. The Heli is always climbing or descending because its so senstive. The problem is the tail rotates one direction when collective is increasing pitch and the heli is climbing, and then when collective is decreased and the heli falls, it rotates the other. If the left right bias could remove this tendancy, by properly mixing the power setting to the main motor versus the power to the tail motor, it would be much easier to fly. You know, instead of waiting for the gyro to sense a change and then apply power to the tail motor, the 3-1 would just add the power in proportion to collective setting. I know this is what a HH gyro would cure, but I've seen a Blade CPPro fly stock set up meaning no HH gyro and it didn't have the rotating problem.

Thoughts? Comments? Corrections? Verifications? Contradictions?

The tail motor on my axe keep coming loose i have to check it before every flite

you might try some semi-perminant loc tite to hold it in

The left/right bias is so you have as much "throw" to the left as you do to the right. Basicly it's like those cheap r/c cars that have the trim tab on the bottom for the steering. On those if you have that trim too far to one side you have awesome turning one way but will be taking a wide turn the other way. The purpose was in case the car didn't track straight, You could trim out the car manually and then use the trim tabs to fine tune it from the controller if it even has trim tabs.

So, If you have the gyro sorted out but your turns are wide one way or overly sensitive in one direction you can manual change the "center" stick to where you have equal throws. This would be much easier to see if the tail rotor was variable powered in both directions(or was two motors and two tail blades counter rotating) because then you would see that one side would have more power than the other. I hope that makes sense.

The problem is getting the two phillips screws on the tail motor mount tight. The proper phillips screw driver to use is a 2 mm. The screw driver has to fit the screw or you can not get the screw tight. You still should check the tail motor assembly during every preflight.