rotor head phasing

[moyesboy]

Friday night I was flying my knight50 in the dark, somehow you see how straight a heli flies and notice errors more in the dark as you can see the disc so well, and it was calm - which it hardly ever is at my usual exposed field in the hills.

My knight was screwing out of inside loops and flips needing right aileron correction. I know my 600npro needs right aileron corerection too in an inside loop.

Looking at my knight on the bench I saw that the pins from the head into the washout block have slipped and the washout arms were no longer in line with the blade grips. The error is the way expected - inducing some left aileron with up elevator. So that is corrected and I'll see how it flies next time out.

now looking at my 600n pro, only change from stock is quick uk swash and K&B yellow dampers (highly recomended!).


See how far off square the washout arms are compared to the grips and flybar. Surely in theory these should be parallel to the spindle and 90 degrees to the flybar. There is nothing assembled wrong and there is no adjustment available. The error is such that it would need some right aileron to correct an inside loop or flip, which is what I find flying it.

The ways phasing can be adjusted are turning the washout base compared to the head block, adjusting the washour links to the swash, or changing the position of the anti rotation post.
I am wondering if the revised elevator lever upgrade (that replaces the anti- rotation post) actually turns the swash to make a correction for this error - or offers some adjustment?
For now I have shaved some off the side of the plastic anti rotation post and packed it off the frame on one side. Moving the anti rotation post toward the left side of the heli. Not enough to correct it fully but we'll see how it goes next time out.

Perhaps someone can explain how the phasing can be correct without the washout arms at the theoretically correct right angle?
With phasing errors, if you fly the model alot then you become very proficient at flying round the problem to the point where you don't see it anymore. You notice things are wrong when you fly different models.

By the way looking at my trex450 rotor head everything looks spot on and that one does seem to flip quite straight for a squirrelly little heli.

[moyesboy]

I expected at least one reply to this, even if was only a cutting comment from Aide.

[steelie600]

tbh gordon im not sure what you can do about it?? youve covered everything available already

[marktigere1]

Thats funny, my 450 squirms like a good un when I flip it.

The Raptor is fine.

[moyesboy]

I wondered:

If everybody found their 600n needs a bit of right aileron in an inside loop?

If the elevator link upgrade, that replaces the anti rotation post, either changes the phasing or allows phase adjustment?

If someone can explain why the head would be designed with the washout arms not 90 degrees to the flybar/parallel with the spindle, when the 450 is square. I also wonder if the 500 has this angle or not?

If I've put my rotor head together wrong in some way?

Gonna be hanging about in here all day as my boy was sent home from school with a bump on his head only just too bad to keep him there.
Chaos to low to the playground again!

[moyesboy]

Thats funny, my 450 squirms like a good un when I flip it.

How straight the heli flips is very much effected by tail/gyro performance. 405 tails are generally a bit sloppy so its hard to get enough gain to not get some swing as you change the collective without getting wag in FFF and bounce on the stops. Plus the wind blows the 450 about and the hover is quite unstable anyway!

[robgt]

You could always get a Kasama head and use that with the Quick UK swashplate - it flies perfectly then :P

The missing element on the Trex600 head is adjustable phasing.
It needs to be adjustable as different makes of blades lead and lag differently, which affects phasing.

You can have a built in offset (like the 600 does) that would work fine in some cases, but not in others, as you've found.

The arms don't have to be parallel with the feathering spindle for a heli's phasing to be accurate - it depends on other factors on that particular heli too.

Cheers,
Rob

[barney]

Moyesboy...I think you have a little problem with the 600 looking at the picture. The arms should be parellel to the main rotor hub.

The pins haven't dropped out of the washout by any chance..allowing it to rotate???

[barney]

AH..you have the upgrade 'A' arm??? did you change the shaft over as the flatspot for the grub screw is located differently. You then need to accurately centre the 'A' arm (or very close if your trying to adjust the phasing)

hope that makes sense

[barney]

I'll prob get shot down in flames here..

As a heli hovers squint (leans)...if you flip it over it will be sitting offset even if the Gyro worked properly 100%.

If you play around you may well get it to flip straight but it will compromise the flying elsewhere. If you want to fly loops...well kinda straightish it will need to be trimmed differently i.e for fast forward flight.

With it trimmed perfectly for FFF so that it requires no Aileron input to keep the rotordisc level..the model will travel sideways...try some loops face on to see what I mean..then back into a hover and it will drift.

A heli in FFF try's to roll cause of Advance/Retarding blade lift of each side is different + a whole load of other stuff way over my head and is a compromise.

Changing H/S requires different trim settings..diff forward airspeeds..diff trim. Upright to inverted too..Blades as Rob mentioned etc etc..

Now changing paddles for instance mucks it all up again as it behaves differently when wind hits it...depending on whats fitted it may drift into or away from a gust etc..

Me KISS..trim it each H/S best you can for straight climbs both upright/inverted and leave well alone.

If I was to setup for F3C I would set it to hover in Idle 1 and use Idle 2 for FFF

[moyesboy]

AH..you have the upgrade 'A' arm??? did you change the shaft over as the flatspot for the grub screw is located differently. You then need to accurately centre the 'A' arm (or very close if your trying to adjust the phasing)

I don't, I've made a slight phase adjustment by moving the standard anti- rotation post sideways with a bodge. However this answers my question if, from what you say, there is some phase adjustment on the a arm upgrade - or perhaps the phase is deliberately different with the A arm upgrade...but that doesn't change the angle of the washout compared to the grips, only changes the geometry elsewhere.

The arms should be parellel to the main rotor hub.

Thats what I think too, but they are not and it is all assembled correctly as far as I can tell. Maybe others could look at their 600n head and see if its the same. However probably it could still fly straight like this if it is compensated for somewhere else like robgt says.


Robgt : I assume the kasama has adjustable phasing as you say the phase is effected by blade choice? or maybe this is just a "my heli is better than yours" type of crowing statement
By the way I have yet to see any mention of phasing differences in several blade reviews at www.50tuning.com Can tightness of the grips make a difference too? I run mine quite tight at the moment.

[barney]

I checked my 600N's one has the 'A' arm installed + my 500 and 700 and they are all the same..all in line to the spindle..

Seems you have a washout prob hence I thought it may have dropped below the locating pins and been lifted back up out of position which would twist the washout round?.

[barney]

Sorry...DOH...my fault.. you have moved the plastic guide across a bit. I would guess it only require a very subtle change to find the sweet spot. I think it is best to go either side of optimium by moving it a fair amount though to see clearly the effect it has..take written notes how it flies as it will help you no end as you go along.

Have you tried trimming for long sustained upright/Inverted climbs That is the most basic setup to get the CCPM working together..also adjust the model CG if necessary as that affects the results if it's a long way out. I would do that first and repeat at each step.

If it were me..and you think there is going to be a major benifit I would try a slightly offset 'A' arm (mine is in the middle to give no interactions though)

A Cycloc might be of more use?

[colin n]

i fixed mine last week.

i see its a sport..ish. bin the plastic bits like , seesaw ,upper mixing arms,washout arms. use the super pro ones and there u go . fixed.

i also added the new swash and A frame while i was doing it. i flies much much better now.

also i see u are on agile 3d holes with that plaggy seesaw and upper mixing arms. thats bad.

as for phasing , i wish my typing was as good as my heli principles of flight. i could go on all day. i would say forget it and buy those parts.

[Rotorhead]

There is a far easier way to sort this, use programable mixes.

Its a better way than adjusting mechanically, and if you cant adjust mechanically its your only choice, since doing it mechanically is very sensitive to small changes in the geometry and very time consuming to get right.

Just set a mix on the elevator so that with stick back you get about 10% right aileron, and with stick forward you get 10% left aileron, and also set another mix for the roll axis, with left aileron set 10% back elevator, and with right aileron set 10% forward elevator, this effectively rotates the system clockwise, which should correct a tendancy to roll left when back elevator is used, and it will sort the other controls out aswell.

It also doesnt care about the models orientation either.

The exact percentages will need to be fine tuned, but the directions they are in should work for most helis.