View Full Version : Bad battery/main-motor/2in1/?

03-30-2010, 12:18 PM
Ok, well my tail started to lose authority recently so I assumed that it was the tail motor going bad. I ordered the DD conversion and installed it. Well, long story short the tail is doing the same thing if not worse. I installed tail correctly and and its spinning the right way. The tail is slowly drifting counter clockwise in hover and even more so with the slightest throttle input(the heli is really hard to control like this, forward flight is damn near impossible). When I go into idle up the tail refuses to hold.

One thing that I find odd is that no matter how high my gain is I NEVER experience any tail wag. I bought a cheap li-po from TrueRc and to be honest I do think that I ran this battery to many times to long. Also the heli has less pop than it used to. Most of the time I forget to start the timer and I'm having to much fun to stop. Anyhow, the main motor has about 50+ flights on it don't know if this matters, could it be going bad(What are the symptoms.)? I'm sure the gyro is fine. It's been through some crashes but was never damaged. The 2in1 that I'm using is in good shape and I don't think that it's the problem, I could be wrong though.

All of this is on a Blade cp+. The only thing that is original is the main motor, servos and the head. The 3in1 is gone and I'm running an AR6200 with dx6i. Also the gyro is the Hobby King 401b, with the DD conversion that I mentioned above. My final Hypothesis is that the problem lies in the A) Battery and/or B) Main Motor. Anyone have any suggestions of where to start or how to figure out where the problem lies? Could a slight vibration cause this bad of a tail drift? Sorry for the long post but if you got this far thank you!!!

03-30-2010, 02:44 PM
That's quite mysterious. I'd tend to suspect the 2-in-1 in a case like this. You could try a new one, and if that's not it, at least you'll have a spare for when you do need one. (That's what I did when I thought mine was going out. I was wrong, but at least now I've got the spare one on hand.) The gyro should be able to power the tail enough without the 2-in-1's help, but the juice still has to physically go through the 2-in-1, which may not be transferring the power well enough if the 2-in-1 is going out. I'm far from certain about this, because it's such an odd problem, especially after you've ruled out the tail motor, but that's my best guess.

I think you're getting no tail wag ever because it sounds like your tail isn't powerful enough to get to that point -- the point where it over-drives, realizes it's gone too far, then under-drives and repeats, which is how tail wag is produced.

The symptom that you've fried your Li-Po is that you're getting less performance and/or shorter run times.

03-30-2010, 07:34 PM
R, does your tail lose holding/authority when your battery is getting low or does it hold good throughout. I assume that you don't let your heli get that far before you set it down.

03-30-2010, 08:08 PM
I've never had that side effect. And actually, I did badly over-discharge a Li-Po once, because I thought it had started with a full charge when in fact it hadn't. So, I watched and heard my power go lower, and lower, and lower while in an indoor hover session, and I had to keep increasing the throttle to compensate. I ruined that pack that way, but my tail never moved. I ran the batt down to almost no lifting power (thinking it was some other thing malfunctioning). Only later did I remember the pack wasn't fully charged to begin with.

John Shipley
04-01-2010, 04:46 PM
The first thing you need to understand when working on a cp or cpp2 is that the tail motor only moves the heli in one direction, nose to the right or in a clockwise fashion. If your heli is turning nose to the left, counter clockwise, this means your tail motor is not running strong enough. The heli turns to the right by using the tail motor and the heli turns to the left using the torque of the main motor.....and the tail motor is off or running very slowly. So your problem is that the mixing pot on your 2 and 1 is not adjusted right. The mixing pot adjust the ratio of power between the main motor and the tail. So take a small screw driver and turn the mixing pot slghtly clockwise and then re power up your rx. If this does not fix it, turn it a little more until it does.
The real test is doing climb outs. Hover your heli and punch the throttle. Does the nose stay straight, turn left or right?? keep adjusting untill you get a straight climb out. There is a fine line in these adjustments so go slow. If you get too much of either the gyro or the mixing pot, the gyro will over drive the tail and it will go crazy.... I covered this on another post...... john