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Mikado V-BAR Mikado V-Stabi/V-BAR Flybarless System Software and Hardware Support


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Old 02-08-2009, 02:40 AM   #1 (permalink)
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Default Phasing: Wobbly Piros, unexpected flight issues. - Check this!

Phasing isses gives all kind of crappy flight performances, just off by a little and your ending up with wobbly piros, tail that moves, barrel rolls etc.

Trust me, you can spend as much time as you want on the bench to get it perfect, you still need to tweak it at the field.

Here is my trick to see if the phasing is spot on or not.

1. Hover tail in, exactly tail in.
2. Do a back-flip (or forward flip) be careful to use only elevator.
3. Watch the tail, if you end up with the tail slightly "off" in any direction, not pointing straight away from you, you have phasing issues.
The tail "enchance" the view of it, so its really easy to see.

(I always forget which direction gives which offset on the tail, so you have to try at the field)

If you change your phasing and next backflip is worse in the same direction, you need to adjust in the other direction, if you get the tail pointing the other direction, well then you adjusted too much.
We are talking just a few degrees here, sometimes just one.

Note: Wobbly piroettes can also be casued by incorrect piro optimization or if that is reversed, in the program the nose should follow the red dot..

Note: Difference between a tail letting go, and phasing issue, is if you do two half-flips (complete the flip) with phasing issues the tail will be back in line when you are tail in again.
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Old 02-08-2009, 03:34 AM   #2 (permalink)
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I've not seen the piro optimization cause wobbly piro's. When the piro optimization is wrong the tail has a terrible feel because it does not respond to the stick correctly/proportionally

Wobbly piro's also happen when the trim is wrong, for example if you have back elevator it will pull that way all around the piro and look really bad

The tail moving during a flip can also be effected by tail/gyro gain and torque compensation settings

Do you think aileron tic toc's are a good thing to check the phasing?
The heli would not tic toc on a perfect axis...
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Old 02-08-2009, 03:40 AM   #3 (permalink)
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Piro optimization rely on perfect phasing, if either one is off you do get wobbly piro.
If you want to "see" how it works, temporary on the bench, raise hiller to 100, apply elevator and turn heli by hand (piro)

No, aileron tictocs are much harder to detect a phasing issue in, much easier in the way described above.


There is a difference on tail moving and phasing issue, and thats if you do a half backflip the tail is off, but if you continue doing the rest of the flip the tail is back again.

A tail letting go due to bad tailtorque compensation wont be back in line after the second half-flip.
(updated original post with this info)
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Old 02-08-2009, 05:45 AM   #4 (permalink)
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Oh, that makes sense, if the phasing is off the piro optimization does not work correctly
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Old 02-09-2009, 09:57 AM   #5 (permalink)
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How you set phasing ???

Is better via software or mechanically ( I think with rotation of swashdriver )


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Old 02-09-2009, 10:01 AM   #6 (permalink)
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Either way will do just fine, same thing, I find it easier to tweak the swashdriver at the field since I can do that without taking the canopy off.
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Old 02-09-2009, 10:38 AM   #7 (permalink)
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Out of curiosity...Is possible set phasing in flybar head without swashdriver ( I can't rotate a washout ) ???

Is possible only by radio ?



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Old 02-09-2009, 10:42 AM   #8 (permalink)
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some has adjustable phasing ring, like Avant Aurora, some dont.
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Old 02-09-2009, 10:55 AM   #9 (permalink)
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Why in trex600's head ( and in the greater number of helicopters ) there isn't phasing ring ? ( is not very necessary ? )


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Old 02-09-2009, 10:57 AM   #10 (permalink)
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Easier to build/cheaper, T600 would certainly need it since its off default, but you can tweak it in the radio by endpoints to get most interactions out.

Thats why 12Z/14MZ with its so superior on a flybar heli, it has all these functionallity to make a heli that fly good, fly perfect instead, and it is a big difference to fly them when they are 100% perfect.
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Old 02-09-2009, 11:08 AM   #11 (permalink)
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ok, In flybar head, If I run at high HS, The gyroscopic precession works at 90.
According to me, If I run at low HS, The gyroscopic precession works at <90....then I need phasing.

So, In some helicopter like trex, logo ecc, there isn't phasing ring because they are thinking to high HS ... or not ?


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Old 02-09-2009, 11:10 AM   #12 (permalink)
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Have no idea, contact align... even old Raptors I think have phasing ring.
My T600 has serious phasing issues due to sloppy swash.

I rather think its because align never did it, and they seem to replicate their smaller on next model...
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Old 02-09-2009, 12:34 PM   #13 (permalink)
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You says that we see tail for phasing, but the problem should be tail, an error on gyro setup, link, low rpm ecc.....or not ?
It's more fast if I check when swashplate go up & down, If it works not in correct way I adjust, or not ?


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Old 02-09-2009, 12:38 PM   #14 (permalink)
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Quote:
You says that we see tail for phasing, but the problem should be tail, an error on gyro setup, link, low rpm ecc.....or not ?
It's more fast if I check when swashplate go up & down, If it works not in correct way I adjust, or not ?
Phasing is Elevator -> Aileron interaction, you wont spot it if its one degree off on the bench, and it wont be visable when swash is going up down, when you flip the heli its like you accedently "bad-stick" it and put in some aileron.

I.e. heli wont be level, but thats very hard to spot, Most visable is the tail since it enchance the effect.

So, easiest way is the way I described it above.
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Old 02-09-2009, 12:56 PM   #15 (permalink)
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ok....you all-right !!!


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Old 02-13-2009, 04:26 PM   #16 (permalink)
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Just a quick comment here.

When you do half backflip and the tail is off, its phasing. When you do half backflip and the disc isn't level anymore and consistently always leans to one side (usually it leans to YOUR right after a forward flip), its the tail not holding. Kinda wierd that pashing offsets the tail and lose tail offsets the disc but thats how things are. I went through hell with this before I figured it all out. I had both btw... :p

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Old 02-17-2009, 07:10 AM   #17 (permalink)
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Quote:
Originally Posted by tchavei View Post
Just a quick comment here.

When you do half backflip and the tail is off, its phasing. When you do half backflip and the disc isn't level anymore and consistently always leans to one side (usually it leans to YOUR right after a forward flip), its the tail not holding. Kinda wierd that pashing offsets the tail and lose tail offsets the disc but thats how things are. I went through hell with this before I figured it all out. I had both btw... :p

Tony
Very interesting Tony! I have the same problems here with my L500. With a forward flip th disc leans to MY right and the tail goes to left.

So what can i do to adjust tail holding to have the disc leveled?
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Old 02-17-2009, 09:21 AM   #18 (permalink)
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You probably have both issues. First introduce a little phasing offset. I would try 1 deg clockwise on all 3 swash points. Check if it gets worse or better (if the tail stays in line or not). adjust as necessary until the bird flips forward with the tail perfectly in line (the disc will be still off). Then start working on your tail. Usually one of the techniques described by MrMel should help you to lock that tail down (increase of "I" probably). That should fix your disc not level issue.

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Old 02-17-2009, 09:55 AM   #19 (permalink)
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Quote:
Originally Posted by tchavei View Post
You probably have both issues. First introduce a little phasing offset. I would try 1 deg clockwise on all 3 swash points. Check if it gets worse or better (if the tail stays in line or not). adjust as necessary until the bird flips forward with the tail perfectly in line (the disc will be still off). Then start working on your tail. Usually one of the techniques described by MrMel should help you to lock that tail down (increase of "I" probably). That should fix your disc not level issue.

Tony
And yours now is flying perfect? Only for reference how many deg on swash phase have you got now?

And also how can i change the phase in the right way via swashdriver? (Or is it better to do it always with software?)

Thanks
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Old 02-17-2009, 10:43 AM   #20 (permalink)
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I'm using the 3Dx head for my Vibe 50 which has the swash driver integrated into the headblock (you can't adjust the pashing mecanically) so I had to use the software to achieve that. Currently I'm flying with 1 degrees offset (clockwise). About the tail, I had some major headache with that but after increasing the tail rotor diameter by over 10mm, I got the tail to hold perfectly (that and increasing "I" as per MrMel's suggestions).

I can say that it flips perfect now. I don't have it perfect on rolls yet (it pitches up a little) but that isn't phasing/tail related. It has more to do with the max/min collective elevator values I think. What is important is that it doesn't break out left or right (which surely indicates phasing issues).

Tony
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