Tail Spin problem Belt CP

[heli-si]

I have just upgraded my Belt CP to carbon fibre frame, tail boom and CNC tail gear and head.

I transfered everything across the sam as on the original frame and now I have uncontrolable tail spin, anticlockwise.

The belt is correct
the rotations on tail and rotor are correct
the blades are the correct way round
The tail servo has the wire coming out towards the frame side and is fitted on the right side of the boom when viewed form above and the lever is to the left when viewed from above (under the centre of the boom)
Te gyro sets ok and doesn't help reversing the switch
I have set the pitch on the tail as per instructions and tried many other settings.

Even with full trim left and full lever movement to the left it struggles to stop the spin.

I have tried reversin the belt and the blades and can't stop it from happening.

Any ideas as I am quite new to heli's and only just mastered short hovers about 1 foot off the ground (don't laugh).

I also tried setting the idle for high revs before pitch added to improve tail stability and that didn't help either.

I did wonder if the exact position of the gyro mattered, I believe it is the same as before. It is a Standard Gyro (not a hold one) and the wires come out at the front left corner, when viewed from above.

Any ideas ?

pictures would help too

[unwind-protect]

I have set the pitch on the tail as per instructions and tried many other settings.

I know you say you've set the pitch on the tail correctly, but the fact that it spins---assuming everything else is correct---says you haven't!

You need to increase the pitch on the tail blades by moving the servo up or down the boom. You may need to turn the servo around in order to get that extra centimetre of travel (check gyro and stick response after this!).

Another thing that can help is to ensure that the tail pitch slider connects to the leading edge of the blade grips, rather than the trailing edge, as this gives you a more useful pitch range (check gyro and stick again!). IIRC you can increase the head speed slightly by turning the 'pitch trim' knob all the way one way, and this will give you slightly more tail power; if you have a computer radio, you have more options here, obviously!

[Pipistrelli]

That sounds like you have the gyro sense setup the wrong way round. The gyro senses a signal but its in the opposite direction, so when it tries to correct it actually makes the pirouette faster.

If you have a reverse switch on the gyro, try that, if not you may need to turn it upside down to get it to 'sense' properly.

[unwind-protect]

My first thought, too, but if it was just the gyro then the spin would not be arrestable by applying full rudder control, which it apparently is.

[heli-si]

I know you say you've set the pitch on the tail correctly, but the fact that it spins---assuming everything else is correct---says you haven't!

You need to increase the pitch on the tail blades by moving the servo up or down the boom. You may need to turn the servo around in order to get that extra centimetre of travel (check gyro and stick response after this!).

Another thing that can help is to ensure that the tail pitch slider connects to the leading edge of the blade grips, rather than the trailing edge, as this gives you a more useful pitch range (check gyro and stick again!). IIRC you can increase the head speed slightly by turning the 'pitch trim' knob all the way one way, and this will give you slightly more tail power; if you have a computer radio, you have more options here, obviously!

I tried what you are saying but the setting to "almost hold" it it actually full travel so the blades are then at full pitch (and this is alot of pitch). So I can't get any more pitch than that and it seems it isn't enough. Even if it did hold it there I would only be able to move the tail on way

If you are looking from above, with the tail towards you, with the standard Gyro, does it matter which way it is fitted and if so which corner should the wires exit the gyro ? Mine are currently on the front left corner.

I replaced the belt gear on the frame end of the belt, I take it these are all the same size so the ratio hasn't been changed ? It was a standard stock Esky part.

This is so frustrating

[Pipistrelli]

True.

I had a similar fault on a friends mini-pred and that turned out to be a loose tail hub, so when the rudder was operated it didn't apply pitch, but the whole hub and blades slid up and down the tail shaft?

Is the hub tight on the tail and it shaft can't slide? Is there any slip between main rotor and tail hub, hold one and spin the other to test?

[heli-si]

True.

I had a similar fault on a friends mini-pred and that turned out to be a loose tail hub, so when the rudder was operated it didn't apply pitch, but the whole hub and blades slid up and down the tail shaft?

Is the hub tight on the tail and it shaft can't slide? Is there any slip between main rotor and tail hub, hold one and spin the other to test?

Done all that and it is all ok.

[Backrowslea]

You obviously do not have enough tail authority....If the tail blades are in the correct way, they spin the correct way and move when you in put rudder then it must be the amount of pitch that they are set to when at middle stick

I had a very slow spin (nose moving left) and had to add continuous rudder to keep it straight, about 1 mm of movement of the servo up the boom and it was sorted...

Are you waiting long enough for the Gyro to initialise i.e. before you move it at all? (steady red light)

[heli-si]

You obviously do not have enough tail authority....

I had a very slow spin and had to add continuous rudder to keep it straight, about 1 mm of movement of the servo up the boob and it was sorted...

Are you waiting long enough for the Gyro to initialise i.e. before you move it at all? (steady red light)

yes, it gives a few beeps and then flashes for a while and then goes steady on.

[Backrowslea]

It will be the ESC that beeps, it should take just over 10 seconds....

[heli-si]

It will be the ESC that beeps, it should take just over 10 seconds....

It's definately "set" when I have tried to fly. I only get a few inches off the floor before I have to land it as the tail spins so fast

[Pipistrelli]

Heli-si,

Where are you, anywhere near Cambs, happy to help if I can?

[heli-si]

Heli-si,

Where are you, anywhere near Cambs, happy to help if I can?

Thanks for the offer but I am on the south coast.

Can anyone let me know if the gyro positioning is critical and which way it should be ? (where does the wire exit) ??

[Pipistrelli]

Can you post some detailed photo's of head, tail, gyro etc. whatever you might think would be useful?

[Backrowslea]

as long as it on the top and the switch is set to rev it doesnt matter about the orientation....