Zeroing the Tail Blades (and tailrod setup)

[R-4-L]

I am just wondering if what im doing is right,

I zero (or center) my tail blades by folding them together and make them exactly level with each other..

is that the way to do it?

its just that I am noticing some drifts when I suddenly add collective, I am suspecting that the blades aren't centered properly that the gyro is kept fighting the bad setup even at hover..

don't know I am making any sense, but Its kinda hard to explain..

Any thoughts?

Ali

[WayneBrown]

Which gyro are you using?
It could simply be that the gain on the gyro are a bit low.

[R-4-L]

thats the first thing i suspected, mine is set to about 85% AVCS (Gy401/9254)

someone told me that it could be that the sudden change in collective gives enough torque that the tail doesnt keep up.

LameBird any comments about my method of zeroing my tail blades pitch?

Thanks

[WayneBrown]

I generally move the blades to one extreme of travel or the other so I get a visual when the gyro initializes, by having it snap to center.
It could be the revolution mixing is still enabled, your linkage is set too close to the center of the servo, or the delay on the unit is set higher than zero, or that there is a slight binding in the overall linkage. I've had this happen, and it's trial and error finding it.

[Ivan]

I have found that when a gyro has to put up with a lot of "vibrational noise" or more abnormal vibrations than normal, it tends to make them jump like what you say. In example, I had the muffler come loose on my vigor the other day, just one of the bolts was loose, the other was tight, yet it imparted enough vibration that I thought the gain was too high, thus I lowered it, and the resulting tail wag on collective was very noticible.

You have stated your gain is at 85%, which is ok on some models, but it could be that for your particular model, it is actually low, especially if you are running a short servo horn.

Look for things that could be loose, like the big wad of extra servo wires that all helis seem to have, make sure it is secure. Other things to look for are loose screws (especially on metal frame helis), buzzing control rods, loose cabin mounts, anything that can wiggle around.

one last thing to check is that your tail rotor control rod is absolutely free, and there is no slop in the linkages. A binding linkage can cause the servo to hang and overshoot in an abruptly changing load. Sloppy linkages can result in the same thing.

I hope this helps. Just keep checking everything over until you find the problem. I will look mine over really good a couple times, and if I can't find the problem, I put it on the shelf until the next day and take a fresh look at it. Eventually it will come to you, be patient.

[R-4-L]

Ivan , thanks for the checklist, it seems that I overlooked some critical things, especially loose bolts (which I had many). however, all my linkages are smooth and free including the rudder,

I set the 85% according to the manual and didn't bother changing it, I think I'll put it higher on my next flight and see if it wags or hunts.

we'll see,, Thanks for the advice :cool:

Ali

[WillJames]

I leave about 10mm or so between the blades when folded together when I do my 90 degree setup at the tail control arm and the servo arm. After you do it enough times you can pretty much eye it and only have to go a turn or 2 if that to get the tail to stay put in Normal Gyro Mode.

[sdixon747]

I would only make one change at a time when trying to solve a problem. If you start changing multiple things, you may fix and then reintroduce the problem at the same time. For example, if you are having some tail wag due to vibration from loose screws, tightening the screws may fix the problem. But if you change the gyro gain at the same time, the gain change could reintroduce the problem. Now you are sitting there scratching your head thinking well I fixed this and changed that and still have a wagging tail. So when tracking down a problem, only change one thing at a time.

Steve

[R-4-L]

Baja !! 10mm ? you mean distance from tip to tip? I always thought that the exact mid point of the rudder must be 0 mm !!!

plz correct me!

[ChrisLaFollette]

Baja is correct. When a heli hovers there cant be 0 degrees pitch on the tailblades and it hold straight. If that were true we wouldnt need tail rotors. :)

[RSL_Mongoose]

This comes from the Raptor Technique site, and its the way I usually set the tail up. Works out almost perfect.

http://www.raptortechnique.com/images/tailpitch.jpg