Stupid beginner questions - nano CPS and DX6

[tomatwalden]

I shouldn't need to worry about swash leveling or any other adjustments on a BNF (or RTF) heli, right? At least not until some wear and crash damage sets in.

Non on the nano-CPS, no. Especially with its linear servos and fixed-length plastic pitch links.

[Heliboy31]

Hmmm OK thanks, maybe I have more issues - I'll try trimming back to zero and rebinding, plus I'll have another look at the mixing screens.

So the bind; when I did it I think I plugged in the heli, then held down the bind button and turned on the DX6 (having set it up on the right model etc.), then I waited for the LED on the heli to stop flashing, then I did right rudder and let go of the bind button.
Should I be holding right stick immediately after turning it on? Before the screen boots up? Then release both when the heli stops flashing?

I'm just confused by the:

Not very helpful, what is 2-3 seconds? Is that once the screen is on? Surely it would have bound by then, so what's the point of the right rudder hold?

/confusion

When I bind my DX6 Tx, I hold the button whilst powering on and continue to hold it until the voice says "Binding 22 milliseconds" and then release. I then wait until the voice tells me that the bind is complete and then do the rudder stick full right thing. Remember to make sure that the throttle stick is fully down, Sw B is in position "0" and the D/R switch is in Position "0" throughout the process. I think the throttle hold also needs to be in Position "0" (off) too.
With your DX 6 Tx you must NOT hold the rudder stick in the full right position whilst powering on the Tx. That procedure is for the RTF Tx.
The point of the right rudder hold procedure I believe is to inform the heli Rx/flight controller that you are using a BNF Computerised Tx Vs. the RTF one. It might also help with some form of calibration which is why you must have the D/R switch in the correct position to allow full right signal to be transmitted.

[tbourner]

Well I've tried re-binding, loosened my rotors back to normal, made sure I initialise on a very flat level surface but in Normal mode (mode 0, blue LED) it still drifts back and to the right all the time - about 20 on the trims to get it to hover in one place.
What else can I check?

[tomatwalden]

Well I've tried re-binding, loosened my rotors back to normal, made sure I initialise on a very flat level surface but in Normal mode (mode 0, blue LED) it still drifts back and to the right all the time - about 20 on the trims to get it to hover in one place.
What else can I check?

There's two things to check ..

1/. That you don't have any trims or subtrims in your DX6. Or that the DX6 isn't giving true zero values at midstick.
2/. That the swash plate is level.

My personal guess would be that the swash isn't level (ie. 2). With something as small as the CPS, you'll need to eye-ball it. Assuming it isn't level, you'll need to lengthen the back servo rod and possibly shorten the front-left. You adjust the lengths by popping the link off the swash, then giving it one or two turns of the plastic bit on the end of the servo rod and popping it back on again. The video below shows the process. This guy goes to town a bit and removes the head to put a swash leveller on. This is just a metal block that allows you to see if the swash is level or not. If your eyesight is good enough - you can work without one. But anyway, it shows the basic process!

https://www.youtube.com/watch?v=hDjQjVqL3WA

[tbourner]

There's two things to check ..

1/. That you don't have any trims or subtrims in your DX6. Or that the DX6 isn't giving true zero values at midstick.
2/. That the swash plate is level.

My personal guess would be that the swash isn't level (ie. 2). With something as small as the CPS, you'll need to eye-ball it. Assuming it isn't level, you'll need to lengthen the back servo rod and possibly shorten the front-left. You adjust the lengths by popping the link off the swash, then giving it one or two turns of the plastic bit on the end of the servo rod and popping it back on again. The video below shows the process. This guy goes to town a bit and removes the head to put a swash leveller on. This is just a metal block that allows you to see if the swash is level or not. If your eyesight is good enough - you can work without one. But anyway, it shows the basic process!

https://www.youtube.com/watch?v=hDjQjVqL3WA

1. Everything looks zero.
2. What mode?
If I'm in mode 1 or 2, I can obviously move the swash to a perfectly flat position as required, just by flicking the ele/ail stick, so how do I know where to adjust it from? I've just thought you must have to do it this way on a full CP heli without SAFE modes - how do you get a start point with all servos in a similar position?
If I'm in mode 0 then the servos all move about trying to correct the movement of the heli, do I need to try to remove the battery on a flat surface before checking the swash? If I do that it looks like the front right of the 3 prongs is actually low, by quite a bit.

[tomatwalden]

The mode is pretty irrelevant - but use HOLD mode as it avoids any risk of accidental spool ups whilst you're sorting it.

What you're looking for is a level swash when the heli initialises. So ... (PS, you might find this all easier with the blades removed)

1/. Power up TX, select HOLD mode. Move collective stick (left) to it's mid-point (this doesn't need to be exact). After this, don't touch the TX anymore or move the sticks.
2/. On a level surface, power up the heli.
3/. Let it initialise and the servos jump to their "neutral" positions.
4/. Check for level. By your description, I'll bet the swash is leaning back and right a little bit!

T

[tomatwalden]

..
If I'm in mode 0 then the servos all move about trying to correct the movement of the heli, do I need to try to remove the battery on a flat surface before checking the swash? If I do that it looks like the front right of the 3 prongs is actually low, by quite a bit.

Yes, this is the slight challenge of these little bind and fly helis. Full size FBL units have a setting that keeps the servos still for this purpose. But on this little machine, you're just going to have to try to avoid moving it too much - at the very least keep it as flat as possible.

[tbourner]

OK, done that, it's definitely forwards and right - so the rear and front left swash arms are the same height and the front right one is lower.

[tomatwalden]

Well, the right will explain the right drift, but if the swash is leaning down towards the front, that would make it drift forwards - not backwards!?

Other possibility is that centre-of-gravity is a bit backwards. If I remember correctly, the nano loads the battery in from the back? Perhaps you're not pushing the battery all the way in meaning that too much weight is behind the main shaft?

[tbourner]

Right, now I'm lost. I just did this:
http://www.bladehelis.com/ProdInfo/F...n-Sheet-ML.pdf

and now it's drifting forwards and to the left! I adjusted the arms (front right anti-clockwise 4 turns, rear clockwise 2 turns) and I think they're all now level. I did the drift calibration again and it still drifts forwards left.

Maybe I need to re-bind, or maybe it's something else, or maybe I should just use mode 1/2 and forget about SAFE mode drift.

[Heliboy31]

Did you put throttle hold (TH) on before disconnecting the battery?
On some of other Blade Helis with Safe, switching on TH loses the trim data just collected
Just a thought.
Incidentally, does it drift in Mode 1 or 2 (or is it a bit too squirrely to determine)?
If it is OK (Driftwise) in Mode 1 &/or 2 then I would think your swash is level enough and the issue lies in the safe system somewhere.

[Peteski]

Right, now I'm lost. I just did this:
http://www.bladehelis.com/ProdInfo/F...n-Sheet-ML.pdf

and now it's drifting forwards and to the left! I adjusted the arms (front right anti-clockwise 4 turns, rear clockwise 2 turns) and I think they're all now level. I did the drift calibration again and it still drifts forwards left.

Maybe I need to re-bind, or maybe it's something else, or maybe I should just use mode 1/2 and forget about SAFE mode drift.

Yes, this is the calibration procedure I mentioned in post #4 which should minimise drift with self-levelling activated, but as I said it's never going to hover perfectly in one spot. It will always drift a bit one way or another. Also you really have to forget about using Tx trims on this heli. They will just mess up your FBL response when you start flying in full CP mode. The best you can do is set the swash level as best you can by eye in mode 2 on a level surface, initialised with no movement or stick inputs and then do another calibration flight or two until it self-levels without any serious drift.

[tbourner]

Incidentally, does it drift in Mode 1 or 2 (or is it a bit too squirrely to determine)?
If it is OK (Driftwise) in Mode 1 &/or 2 then I would think your swash is level enough and the issue lies in the safe system somewhere.

Haven't tried yet, the cat refused to move and I didn't fancy risking it with my current skills!

Yes, this is the calibration procedure I mentioned in post #4 which should minimise drift with self-levelling activated, but as I said it's never going to hover perfectly in one spot. It will always drift a bit one way or another. Also you really have to forget about using Tx trims on this heli. They will just mess up your FBL response when you start flying in full CP mode. The best you can do is set the swash level as best you can by eye in mode 2 on a level surface, initialised with no movement or stick inputs and then do another calibration flight or two until it self-levels without any serious drift.

Thanks Pete, I've done the swash in mode 0 when initialised on a level surface - is this different than initialising in mode 1 or 2 then?
So I put Tx on, Hold on, Mode 2, plug in heli, unplug heli and then level the swash? I can try that.

[tomatwalden]

Also remember left-drift is normal. I'm not sure how much SAFE may try to counter-act this, but once you progress beyond such micros, counteracting for left-drift becomes instinctive anyway.

[Peteski]

Thanks Pete, I've done the swash in mode 0 when initialised on a level surface - is this different than initialising in mode 1 or 2 then?
So I put Tx on, Hold on, Mode 2, plug in heli, unplug heli and then level the swash? I can try that.

Not sure on the mode 0, I was just thinking that self-level might be active in mode 0, which would make it impossible to tell if the swash was really level as the self-levelling can sometimes make the swash tilt while the heli is static on the ground. If you use mode 2 for levelling the swash at least you'll know there is nothing else affecting the swash position. But you still have to keep the heli very still as the swash will react to counter any movement. You also ideally want to have the swash at zero pitch when you check it's level, which will probably be mid stick on the throttle presuming you have a linear TH pitch curve. To make it easy you could temporarily make your pitch curve in TH a flat 50% so the stick position doesn't matter. Actually for micros like this, fixed zero pitch on TH is a good thing anyway so you could leave it like that permanently - which is what I do with micro helis. Makes it really easy to check zero pitch by folding the blades back too.

With the above in mind, your method sounds good. Finally, just remember that you are checking the swash level relative to the main shaft, not the ground. I thought I'd mention this because the main shaft may well be slightly tilted forward when sat on the skids.

Edit: One other note, always check the swash level when it's powered up, as the swash will move while you are unplugging the battery. But obviously make any adjustments without any power and then power back up to re-check.