vibe 90 and dx7 swash leveling problem

[whittm]

Ok, had a bit of time today and had been watching this excellent vid on setting up flybared heads for the last few weeks and felt confident at having a go:

https://www.youtube.com/watch?v=Br9YdUTDenQ

I managed to very quickly setup servo direction in the swash mix tab and then, the servos at 90 deg using sub trim. Then I hit a problem, I stripped the head off ready to level the swash, flipped the heli in to flight mode 1 and then noticed something strange as I flipped between Normal, flight mode 1 and 2.

In flight mode 1, the swash is almost level, just needs a few turns to get it right. But as I flip the switch in to flight mode 1, the left servo 'flips up' a few mm and the right servo jumps down half a mm to a mm. When you flip in to flight mode 2 it jumps back to the original position. I've checked pitch curves and they are identical in all 3 flight modes... so, I'm a little stumped! Any ideas anyone?

I don't want to go through the setup and then find out there's something drastically wrong!

[waveydavey]

Have you got independant trims in flight modes.

[whittm]

Thanks ...again! One more thing....I'm looking for a crib sheet with all the settings for the dx7, I've looked on the web to no avail. Even though the thread says Vibe 90, it's actually an Airskipper 90 so could be slightly different.

I have the crib sheet for two types of Jr radio, the pcm10x and the pcm9x, but both are different, so i'm guessing that the dx7 would differ also?

[waveydavey]

When you say crib sheet do you mean Tx settings for your particular heli, if you do I wouldn't worry and go through your setup as you're doing. Ask away here and you'll soon get there.

[whittm]

Yes... that was what i meant. I'll finish setting up the head first then, thanks again!

[trillian]

I think some settings will still apply but when it comes to travel adjusts the Spektrum displays a range of 0 to 150 instead of 0 to 100. But basically you just want to go for maximum throws on the swash without binding, levelling at the centre as well as top and bottom collective, be mindful of not using too much subtrim and keep an eye on the subtrim combined with travel settings (not pushing a servo too far), stuff like that.

[whittm]

Just leveled swash, sub trims are:

Thro: L33
Aile: R31
Elev: U51
Pit: H6

[whittm]

Ok, I've setup the head and finished balancing the blades. I've also centred the throw on the tail blades so no more bind at either end. Now I've got the pitch to setup. ...on the video he lengthens each swash link equally to get the swash centred in order to get equal pitch angles in high and low.

Trouble is on my heli, there is a linkage and two control links leading to the elevator. If I Were to lengthen the pitch and aileron links and then try to do the same to the elevator linkage, would say 1 turn on each linkage have the same effect on the swash in all three arms?

I.e.will the linkage have a ratio effect on it, will it move more or less than the other two arms given the same number of turns?

[waveydavey]

You should set the swash level before setting up the head. If you're doing it afterwards then you would need to alter them all the same amount.

You should have gone with the manual settings for linkage lengths etc and as long as your servo horns are square then you should be in the ballpark. I would have tried to get the mechanical as close to 0 as I could without using subtrim and I wouldn't have used it to level the swash as it means the servo centre isn't any longer.

I would centre the servos as best you can with the horns you've got and then subtrim to get them square. Then add the swash into the equation adjusting the linkages to get it level. Then I would set the head up, as long as the linkages to the head are to the manual then you shouldn't be far out. I wouldn't worry too much about moving the swash afterwards to get centre, as long as you're to the manual you won't be far out

[whittm]

You should set the swash level before setting up the head. If you're doing it afterwards then you would need to alter them all the same amount.

You should have gone with the manual settings for linkage lengths etc and as long as your servo horns are square then you should be in the ballpark. I would have tried to get the mechanical as close to 0 as I could without using subtrim and I wouldn't have used it to level the swash as it means the servo centre isn't any longer.

I would centre the servos as best you can with the horns you've got and then subtrim to get them square. Then add the swash into the equation adjusting the linkages to get it level. Then I would set the head up, as long as the linkages to the head are to the manual then you shouldn't be far out. I wouldn't worry too much about moving the swash afterwards to get centre, as long as you're to the manual you won't be far out

Ok, I did exactly as you just said, that's how the vid showed as well, unfortunately, I did not build the heli, so I don't know if all the links are bang on. I've just checked the pitches:

@ mid stick on one side of heli = 0.8 deg positive
@ mid stick on one side of heli = 0.3 deg positive

I can't adjust it any closer with the links.

Full positive is 8.5 deg
full negative is 12.1 deg

So, quite a way out! what's best way to tackle this? Adjust the links to the swash? Or, adjust the travel til I get 12 deg positive and negative?

[whittm]

Right, I've done that:

Mid stick = 0.1 deg on one side
= 0.6 deg on the other

high = 10.2 deg
low = 10.2 deg

I adjusted the links from the servo to the swash and the swash is still perfectly level! Thanks!

Next question. In the video I linked above, he suggests using Travel adjust to get 12 deg positive and negative and also to use travel adjust to adjust aileron and elevator, is that the best way to go?

[waveydavey]

Yes and no, let me sober up slightly and I'll answer in the morning

[whittm]

again, as i could see the pitch change as i rotated the head, i did this by

[whittm]

Got both blades at 0 degree pitch in one position at mid stick and then used subtrim to get 0 degrees in all four directions on the heli. I did this again, as i could see the pitch change as i rotated the head.

It now shows within 0.3 deg pitch on both blades in four orientations.

I then used pitch subtrim to centre the collective pitch going full high and low collective and adjusting the subtrim until they were identical, 10.1 degrees in this case.

All I need to do now is, adjust the throws. ..not had much luck so far. ..Any ideas on the best way to do this?

[trillian]

Got both blades at 0 degree pitch in one position at mid stick and then used subtrim to get 0 degrees in all four directions on the heli. I did this again, as i could see the pitch change as i rotated the head.

It now shows within 0.3 deg pitch on both blades in four orientations.

I then used pitch subtrim to centre the collective pitch going full high and low collective and adjusting the subtrim until they were identical, 10.1 degrees in this case.

All I need to do now is, adjust the throws. ..not had much luck so far. ..Any ideas on the best way to do this?

It sounds like you're getting there. How much cyclic pitch are you getting now? (well basically on a flybarred model you want to get as much as the swash will give you without binding as you'll need every bit of movement available). 10 degrees collective is not a bad place to start, it should be fairly lively at a governed 1900 ish headspeed in idle-up, 12 degrees will require very good collective management or an extremely well tuned engine on high nitro.