250 Tail wagging Blade 300 X

[Boogs]

Just finished the restoration of my 300 X, new Spektrum H3050/60MG and an AR7210BX. Did my maiden and the tail is wagging, like my dogs when I come home. This is my first belt driven tail so I'm asking for direction here. Everything is set by the book, I was able to take off, hover and land, just need to stop that tail wag.

 

[Tony]

Where is your tail gain set at and what Tx are you using? I'm sure you have stated this in another thread, but you know, getting old and bad memory lmao.

 

[Boogs]

I'm using a first gen DX8, gain is set at 54? Something I didn't understand in the Tx setup was the tail curve, not sure where that's at in the setup menu. You got CRS too?

 

[Tony]

Yes I do, a horrible case of it lmao. And 54 is a bit high, try going down to 45. Sounds like the gain is just slightly too high. If 45 does work, try 40.

 

[Boogs]

Got it, will give that a try, hope it doesn't start raining before I can get 'er done!

 

[Tony]

Here it is just the wind, as usual.

 

[Boogs]

We've had that too, Delta breeze has been strong past few days. OK for a flight report, you're right on Tony. Started at 45 and kept dropping it by 5 until I hit 20 and ran out of time. Much better so I'm on the right track. Thanks! Oh, and it started sprinkling.

 

[Tony]

20 is usually too low. Might want to make sure everything is nice and smooth on the tail. If there is any binding, that will cause what is known as a 'hunt'. With the gain too high, it is known as a wag. You are getting low enough for it to start hunting. But, I have never flown a 300 so I'm not sure how low you can go.

 

[Boogs]

Everything feels smooth, cleaned and fresh lube on the shaft. Tail pitch slider works smooth as silk. Question, how tight/loose should the tail rotors be?

 

[Tony]

The tail blades? I like mine just tight enough as to not fall under their own weight when they are horizontal.

 

[Boogs]

OK, looking at the pitch control arm and the pins appear worn, I'll adjust the blades and get a new slider and control arm. Already have the shaft/pulley/bearings on the way. Never hurts to have spare parts for what you're flying, or in my case, trying to fly.

 

[Boogs]

Considering the wag or hunt as I'm thinking is more accurate, I'm thinking the problem may be that when I setup the tail, I centered the servo rather than allow some pitch to counter the rotational force of the main blades. So. How much off center and which way? I understand the end points will have to be re-adjusted, but as I said this is my first attempt at building/restoring something other than a DD tail. Today I noticed the tail moves a little left, stops then moves a little right, stops and then left, right, left, right.......

 

[Tony]

There really isn't a set amount of pitch. It all depends on how much drag your helicopter has. Usually you will just set the slider on the tail shaft right in the center, then do your endpoint adjustments and you should be good. If you want a little pitch and you have a clockwise rotating head, then you will point the trailing edge of the tail blades to the right when looking at it from behind.

 

[Boogs]

OK. That's what I did, so now it's the waiting game for the new parts to arrive. Thanks Tony!

 

[Boogs]

The mechanical side seems to be right, the alignment of the control arm is straight no binding, the slider will fall if I just even touch it (arm off). I found I'd used the wrong Hz value for the tail servo and fixed that and went back to the factory recommended gyro gain. Still wagging. Started going down in smaller increments and it's better at 35, but still there. By that time the battery alarm was going off so I landed. Noticed the gear train was tight, like the mesh had tightened up. Flew my 230 and after that, the gear train on the 300 was back to normal. Motor? Could the motor going bye bye be causing vibration that is wagging the tail? Think I'll go ahead and put the new one I have in and try that.

 

[Tony]

If the mesh got tight just by flying, I would imagine something is not tight. Metal (steel) will only grow .001" per inch with a 100º increase in temp, and these parts are very small so we are talking maybe .000000001" of expansion of the metal parts on these helicopters.

As for your next question, yes, a motor going bad can cause some weird issues including increased vibration. Give that other one a shot and keep us posted.

 

[Boogs]

I'm thinking the bearings might be seizing up in the old motor. Putting the new one in, was going to do that anyway. It's nice out on the porch, a cold beverage in hand. What else can you ask for?

 

[Tony]

I hear that! It's not a bad day here either, but have more crap to do inside but may try to get out to the garden later on today and do some weeding or something. Winds are pretty low but have nothing in flying condition just yet lmao.

 

[Boogs]

Pulled the old motor and discovered I don't have the right pinion. OE is a dual size motor shaft and the Scorpion isn't, plus I have 13/14t gears. This motor was for another project. Stock pinion is 9t. Cleaned and lubed the old motor and stuck it back in, no difference this morning. Be placing another order today, if/when I make up my mind to get another motor, or just the pinion for what I have. Argh!

 

[Tony]

Yea, I ran into the pinion issue with the latest build, the ALZRC 450. It came with a pinion but the ID was 3.5mm and the motor shaft on the Scorpion motor is 3.18mm or something like that (1/8"). so it had a wobble. Thankfully I had another pinion laying around to put on it, but it is not stock.