What have I done wrong?

[powelly999]

Hi all
I recently posted regarding me dusting off my unflown, not setup TREX 470l. I’ve followed the advice given me on the post answers and managed, I think, to go through the beastx setup. The issue I have is with the tail servo. It is acting very peculiar, it moves from end point to end point when using full stick, and only works proportionally when the stick is moved in very small movements around centre point. I’ve been through the setup a number of times but it always ends up the same.
Not sure if I’ve explained it well, but can anyone shed some light on where I’m going wrong?

Thanks
Andrew

[trillian]

I assume this is just what you're seeing on the ground.

When you move the tail abruptly (the actually heli, not the TX stick) do you see the tail reacting to compensate?

My first thought is that it is probably just the gyro trying to give you the movement you're requesting, as it does not know it's not in the air

[powelly999]

I assume this is just what you're seeing on the ground.

When you move the tail abruptly (the actually heli, not the TX stick) do you see the tail reacting to compensate?

My first thought is that it is probably just the gyro trying to give you the movement you're requesting, as it does not know it's not in the air

Ahhh yes, it does react as if the beastx is doing the gyro compensation as you would expect. It just seems odd but maybe it does react like that. I have I tried another servo and the same happens. I just didn’t want to try to hover and it all goes pear shaped!

Thanks
Andrew

[trillian]

When you do your first flight, just make sure first that it is reacting in the right direction, that the gyro sense is correct. Then, just to be sure, before lifting off watch very closely as it begins to get light on the skids to make sure the tail is not going to spin as soon as you lift off.

Similarly you can visually verify the swash is compensating the right way by tilting the heli and the swash should be reacting the opposite direction, essentially remaining level.

[powelly999]

When you do your first flight, just make sure first that it is reacting in the right direction, that the gyro sense is correct. Then, just to be sure, before lifting off watch very closely as it begins to get light on the skids to make sure the tail is not going to spin as soon as you lift off.

Similarly you can visually verify the swash is compensating the right way by tilting the heli and the swash should be reacting the opposite direction, essentially remaining level.

Many thanks trillian, it’s all a lot different from my old Shuttle and Sanwa!

Thanks again.
Andrew

[ian4655]

Tail issue

Hi,

Rule of thumb with flybarless, thanks Alan Robinson. EVERY time you connect power, wait until the swash does its little dance, without moving the model. Then, check the swash compensates in the opposite direction to the way you tilt it, that’s fire back left right. Check the inside edge of the tail blade, trailing edge, moves towards the heli boom in compensation.

As has been said, the reaction on the ground is different yo in the air. Don’t give it full beans as you will maybe have an out of control Heli 20 up in the air, watch it light on the skids, if the tail holds do some ground hovering, a few inches above the ground and move the tail left and right. If it holds be a bit more adventurous until you have confidence in it.

Best of luck, let us know how it goes, doesn’t sound as if you have done anything wrong just the way the newer fbl units work, I HOPE.

All the best.

[powelly999]

Hi,

Rule of thumb with flybarless, thanks Alan Robinson. EVERY time you connect power, wait until the swash does its little dance, without moving the model. Then, check the swash compensates in the opposite direction to the way you tilt it, that’s fire back left right. Check the inside edge of the tail blade, trailing edge, moves towards the heli boom in compensation.

As has been said, the reaction on the ground is different yo in the air. Don’t give it full beans as you will maybe have an out of control Heli 20 up in the air, watch it light on the skids, if the tail holds do some ground hovering, a few inches above the ground and move the tail left and right. If it holds be a bit more adventurous until you have confidence in it.

Best of luck, let us know how it goes, doesn’t sound as if you have done anything wrong just the way the newer fbl units work, I HOPE.

All the best.

Thanks Ian, charging batteries as I type ready for my first Heli flight in over ten years tomorrow!
Regards
Andrew

[Grumpy]

Thanks Ian, charging batteries as I type ready for my first Heli flight in over ten years tomorrow!
Regards
Andrew

Good luck!

[Magic919]

I hope it goes well.

[powelly999]

Mmmmmm.....
All is not as expected, just as it goes light the tail starts to move anticlockwise. The rudder servo still operates strangely I think, around centre stick, you can move it slowly in the correct direction but with only very small inputs on the stick. Also, when you let the stick go back to centre, the servo does not go back to centre point but stays in the position you moved the rudder to. I know I’m not used to this set up, but surely it can’t be right? I didn’t want to risk taking it to a hover as I was unsure if it would be controllable. Back to the drawing board!

I’ll keep you posted
Andrew

[Grumpy]

check carefully that the gyro compensation is not reversed.

The behaviour you describe (tail staying at full travel even when you centre the stick) is perfectly normal for a heading hold tail gyro when operated static on the ground.. they all do it.

[Grumpy]

The reason why the tail behaves like that is because on a heading hold gyro you aren't controlling the servo directly. When you move the stick you are telling the gyro that you want the heli to yaw, how far you move the stick controls yaw rate (in degrees per second). So for example if you move the rudder stick far enough over to give a 45 degrees per second yaw rate, and you hold the stick over for 2 seconds then (in flight) the helis will rotate by 90 degrees, then stop. When the heli is on the ground it cant rotate, so if you gave that command the tail rotor would stay 'over' waiting until the heli had achieved the 90 degree rotation.

The anti-clockwise turn you are experiencing might be because you didn't zero the pitch on the tail blades prior to spoolup.. or it could be because you have gyro compensation reversed.

[The Tok'ra]

On the 470L, Which is the same as the 450L, has leading edge tail blade control, so.....with the heli powered up, TH on. heli sitting on it's skids on a bench or table top, push the tail sideways with your hand while looking at the tail pitch slider. The pitch slider should move in the opposite direction to the way you are pushing the tail.

Another thing to try is this. Also on the bench, as before, move the rudder stick left, the pitch slider should move right. Move the rudder stick right, the pitch slider should move left.

If either of the above do not do as expected, you have something wrong in your set up. Either the gyro compensation is reversed, the rudder channel is reversed, or both.

[trillian]

I always think of it this way: If you're looking at the tail, the heli is facing away from you, the tailrotor has to blow air to the right to compensate for the rotor torque. Then if you move the stick to the left, it will try to blow air to the left in order to move the tail to the right (and thus, nose to the left). If you move the tail quickly one direction or the other the gyro will change the tailrotor pitch to blow more air in the same direction in order to try to keep the tail stationary.

There are a few ways I have heard over the years to remember which way the pitch slider should move etc. but I just find that thinking of it in terms of where it's blowing air is the easiest for my brain to process

[ian4655]

Tail issue

Just a thought, you have the correct timing setup for your servos in the beast?

Otherwise, as has been said, the tail behaviour is more or less correct on the ground with the beast.

If compensation is reversed it could well give you this issue.

Try what has been offered today as it is sound advice.

Shame you didn’t have a successful day today, but better to take small steps than bloody great big ones to the shop for spares.

Good luck and don’t forget throttle hold.