700LE tail drift

[mark_w]

I am still having problems with the tail drifting clockwise on my 700.

I changed the gyro over to a 401 that I had, and now it drifts the other way.

It drifts quite quickly, almost like its in rate mode and not setup, so I have to keep the stick over to one side to correct the tail!

Any ideas welcome,

should I try another servo?

The tail is not 100% vertical, should I widen the slot in the boom so I can twist it round, and would this cause it to drift?

[Andy from Sandy]

When a model turns on its own I always think of a vibration somewhere. But the tail would normally go anti-clockwise with the torque of the engine. i.e. Tail to the right when doing a tail in hover.

[rapidgaz]

could be a hunting problem coming from a bad tune on the engine

[mark_w]

I will put the align gyro back on and double check direction. I don't get much vibration and engine was tuned by a sponsored pilot, who also test flew it and said it was running good.

I might take the boom off and check eveything

[trillian]

'Not sure why the tail assembly wouldn't be vertical on the boom but unless it is way off it should still work OK (or at least I doubt that would cause the drift).

On the 401, it needs to initialise in HH mode when you turn on the rx. It needs to not be moved until it initialises. It will memorise whatever rudder trim on the TX as the centre position, so if you change flight modes and have different rudder trim you'll have a drift.

I use no rudder trim with the 401.

Assuming the mechanical setup is good and there's no rudder trim and it is initialising properly then it does kinda sound like a vibration issue but so far I have yet to have a vibration problem with a 401 on any of my helis using the standard Futaba gyro tape and sometimes some thicker tape and sometimes using a strap as well just for safety.

So for it to be vibration it would have to be something really dodgy with the gyro tape. (assuming, as you say, there's no noticeable vibration on the heli otherwise).

What gain are you using? (it will probably run at a very different gain value than the Align gyro). Mine run anywhere from about 72% to 81% (below 50% it goes into rate mode and the gain value is reversed where 50 is like zero gain and 0 is 100% gain in gyro mode on the DX7)

[Nick B]

Helped a mate with his 401 a few weeks ago,he had drift to the right.The cure was getting the right pitch on the tail in rate mode.

I had drift to the right on a 750 on my 600,a second pad and the metal plate in between sorted it.I leaned out the engine to try and stop it with no joy,no foam in the tank so wasnt and engine vibe

[rchelispares]

have you tried rebinding if your running 2.4ghz?

[Paulo uk]

Have to agree with it being vibration. Try adding gyro pads or foam until the gyro kind of squidges when you twist it... if that makes sense...

[mark_w]

The 401 was a test to check that my gyro was not bad, so the align gyro will be going back on. I already have 2 align pads with the metal plate between so the gyro has plently of padding.

I will double check the gain settings, but I have set this gyro up on my 600 with no problems, so I dont think its that.

I will also try a rebind.

Just to add I have no trim or sub trim set

[cupracing]

Is the engine getting hotter than usual? Could indicate the torque tube is too tightly meshed with the front or rear gears.

[Andy from Sandy]

I had drift to the right on a 750 on my 600,a second pad and the metal plate in between sorted it.

This suggests your model does have a vibration but you cannot see it. All single cylinder engines cause vibration else why go to all the trouble of using loctite?

I would hope most gyros have an anti-vibration algorithm. The CSM SL720 is quite sensitive but is a good indicator when things start to go wrong with the model. e.g. the bearings in the engine are knackered.

[mark_w]

I will take the TT out again tonight and have a look. When you put the boom in, do you push it in all the way, then just ease it out a fraction so the TT is not in tight?

[Andy from Sandy]

I pushed the TT on mine in as far as it would go. I have the pinned TT on the LE so it has to be pushed in until the holes line up. I never bothered checking for backlash.

[mark_w]

Update..

I Rebound the tx and rx, and re setup the gyro (align one).

Went to test it today, took off and it was still drifting, then after about 20 seconds of hovering, there was a bang and the heli piroetted out of control

bust the blades, skids.. etc

Any ideas to what cause this are most welcome . The TT was/is all free and driving the tail fine, everything seems to be free, so I have no idea what is going on

[mark_w]

anybody?

Really out of ideas and need help