Miserable day...losing faith

[Gibbo73]

So I knew I had a ******* tail servo, thought the tail output shaft and main shaft was shot(bad vibrations) so I bought new. Just fitted the new bits...servo is just as shot brand new out of box, and still have a wobble/vibration in the head...

Fed up. Need a club to join but there are no heli clubs near me.

Today is a sad day

[PKNEC]

What copter do you have?

[cjcj1949]

Things can be tough at times. It gets easier though and you just have to keep going. There are probably people around you that can help, where exactly are you? Can you test the servo independently? Swoping things is often the only way to prove things are faulty. What servo is it? Do you have a multimeter to check volts with?

[Gibbo73]

It's a JP Twister CPX...it's very much an entry level CP heli, but still, you want it to work dont ya...which it did, but now...well, now I'm thinking "I'm only a couple more hundred away from a T-rex" :-/

[Gibbo73]

Things can be tough at times. It gets easier though and you just have to keep going. There are probably people around you that can help, where exactly are you? Can you test the servo independently? Swoping things is often the only way to prove things are faulty. What servo is it? Do you have a multimeter to check volts with?

I'm in between Hereford and Brecon. The servos, one brand new, the other came on heli, are both doing the same thing, sticking. One time it'll move all the way to the left and stick...another time it'll get stuck to the right..the movement is really sticky/juddery. and sometimes it will barely move either way. It is an S7.5D servo(by JP), and no, I dont have a multimeter :-(

[cjcj1949]

I started with a twister storm. The small helis are very good as they survive most crashes. The trex helis are very good mechanically. Clone 450s are much cheaper and there are good cheap motors, servos and gyros available. Lots of threads on here. You won't find the trex any easier to fix. Many faults are easy and obvious, but the obvious is not always right. It's all part of the challenge. I've just gone through a lot of problems caused (I think) by a bad batch of servos. Sometimes one crash makes something else go and you can get a bit desperate.

[cjcj1949]

Does the servo stick if you disconnect it from the tail? You may find the tail is sticking because of the geometry of the links. I've had the problem due to too much throw. Servos don't usually stick at one end of their travel, especially not when its a replacement. It sounds as though you've changed the wrong part.

[Gibbo73]

I think the thing that's getting me down is that I feel so out here on my own with it all...I mean, just dont get what's going on with it and I've noone to bounce things off. Forums are ok but it's not like having someone next to you going, "ahh your so-and-so has gone mate..." As for the T-rex, I just figured the quality of build will be better from the off, less chance of shoddy bits? No?

[Gibbo73]

I took the horn off and watched the splines...checked it with horn on but linkage off...do...not....understand...ah well...go out, look at it again tomorrow!

[pgkevet]

Vibration affecting the gyro, chafed wiring somewhere causing spurious signals or the rx socket signal pin damaged would be my first guesses. You're not far from hereford and I can't believe there's no heli club around that way. My bit of mid wales is just north of welshpool..probably a tad far for you to want to come.

[Gibbo73]

So, here's an update...I've unplugged the gyro and plugged tail servo straight into channel 4 on the rx and the servo behaves as normal. I find it hard to believe that the gyro was shot from new, but that's how it looks to me :-/

[askeys_heli_madness]

So, here's an update...I've unplugged the gyro and plugged tail servo straight into channel 4 on the rx and the servo behaves as normal. I find it hard to believe that the gyro was shot from new, but that's how it looks to me :-/

From reading your earlier post re sticking servo at extremes of travel and your quote above implying you think the gyro is shot I do not think your gyro is shot but behaving perfectly normally!! Read on and I will try to explain...........lets hope I am right!

If your gyro is running in 'heading hold mode' then when you enter in a rudder command the gyro will tell the servo to move to force the helicopter to turn in that direction. However you are testing on the bench ie stationary helipcopter and the helicopter will not move! The gyro will force the rudder servo to maintain its postiin until the gyro 'feels' that the helicopter has reacted to the input ie your rudder stick movement and moved to that position.

Try this. Plug tail servo back into gyro. Plug battery in and give full rudder input in one direction. The servo will stay where it is as the heli has not moved and the gyro has not sensed a change in direction. Now let the rudder stick move back to mid position, servo will stay where it was. Now pick the heli up and rotate slowly in one direction and then the other. The gyro will sense this movemement and force the rudder servo to move.

Not sure what transmitter you are using but on most (if set up correctly) there is a switch so that you can toggle between 'Heading hold' and 'rate' mode for the gyro.

'Heading hold' mode. The gyro keeps the nose of the helicopter pointing in the same direction no matter what (ie gust of side wind) unless there is a rudder command generated by the pilot ie you moving the stick on the tx.

'Rate' mode (when mechanically setup correctly) will generally cause the nose to follow in the direction of travel, rather like a windvane. However if a gust of wind catches the heli side on it could cause the heli to rotate into the wind ie it moving without any user input. The pilot then needs to correct this by giving additional rudder stick input.

Hope that helps and keep your chin up. As others have said, you have bad days and good. The good days cn be bloody fantastic but on the flip side the bad days can be just as bad.

[Gibbo73]

Think I should have picked stamp collecting, you can do that on your own! Cheers for the reply, it kinda makes sense to me as well...let me give a few more details as to what's been happening for me.

Firstly, when I got it, the chap in the shop said to set tail up so that the pitch on the tail blades is at zero when heli is plugged in and at rest (this sounds counter intuitive as surely it needs some pitch to counter torque, or does the gyro help here?)

Ok, so I get her in the air, and even in HH (yes, TX has HH and rate mode) it'll weathervane roughly 45 degrees nose left, when I input right rudder to straighten up, thats when the tail wags/vibrates quite violently(have tried turning gain on gyro down). Let off the rudder input when she's back to perfect tail in, and she will weathervane back to 45 degrees nose left.

It was the wagging/vibrating and the strange(I thought strange) tail servo behaviour that led me to believe the servo/main shaft/tail output shaft were gone...now I just know that I know nothing! :-)

[cjcj1949]

You have made the first step. Helis are not easy as very little is written down. Even when you have worked in electronics and flown rc for a long time it is still often very difficult. Other people are your best bet and you need someone to check your heli out. Very often the man in the shop doesn't know that much.

With heading hold the gyro will work if set to zero pitch. This is because the electronics behind the servo will move the tail to the correct position and leave it there until it needs to be moved to another position. The initial position doesn't matter. There is a disadvantage to this setup which is it won't work in rate mode. A better setup is to put it in the correct position. On a 450 the angle is about right when you are outside the back of the skids looking along the blade. Roughly an extra skids worth.

I switch on in hold mode and then switch over to rate mode as hold mode tends to drift and is affected by transporting the heli. I switch into hold mode just before takeoff.

If you search through the posts you'll find info on most things. There are a lot of things that are not obvious. Like discharging lipos. If you discharge them fully they won't last long.

Don't worry about asking questions. You'll get lots of help. Often you won't get the answers that you want. Flying a 450 is amazing though and there's always a challenge if you want one.

[Gibbo73]

Thanks for that, reading your words has made me feel a little better. I will have to wait until I can get to test her out again, but perhaps the future aint so bleak :-) Any idea as to why the nose was yawing to the left and sitting there? It's like the HH was set to hold it at 45 degrees nose left...