Phasing.. I think...

[Baldie]

Flybarless IS the future !!!!!!!!!!!!!!

x Rachel

Hehe Until theres a powercut
Im sticking with steam and gas!!!

seriously glad this topic came uup. had this with my trex 450. and now with 500 but not with raptor !
tried to mix it out to no avail.... will look at it again now .

[Eckchaz]

Hehe Until theres a powercut
Im sticking with steam and gas!!!

Wow.. your Rx and servo's are powered by gas and steam on your FB Heli's?!

[scallybert]

It isnt independant of RPM, changing anything like the RPM, the blades, or the tightness of the blade bolts can change the lead/lag angle, and it is this that adjusting the phasing is for.

I think I may have been unclear.

There's a theoretical 90 deg phase lag between the cyclic pitch of tbe blades, and the precession of the rotor disc. ie the max blade flap up is 90 deg after max cyclic.

However, in practice this angle isn't exactly 90 deg - being affected by those factors you say, and maybe others.

[Apart from anything else, the blades appear stiffer at higher RPM, affecting their natural frequency. This natural frequeny then interacts with the head speed.]

So, we agree there.

What I was referring to was whether the correction angle input via mechanical or electronic means was constant across headspeed.

I'd expect it to be (but may be wrong), hence the correction wouldn't be right at various headspeeds. There's a suggestion (with a reference I need to read), that the mechanical phasing correction deals with this somehow.

[trillian]

As i am quite a simple bloke i tend to look for simple reasons to cause and effect, not wanting to seem like i'm trying to teach anyone to suck eggs but i feel most fazing issues are down to mechanical set up,

Actually, unless the heli has adjustable swash timing, usually via washout guides that are not mounted permanently to the head and can be set a few degrees one way or the other (which it seems most helis do not have). The mechanical setup will have virtually no effect on the phasing (or swash timing, whichever you want to call it).

But I think the jist of what you're saying, quite rightly, is that most issues are due to the setup and not swash timing in the first place. So setup issues that cause interactions are often the culprit moreso than the rotorhead design.

On my helis, only 3 have adjustable swash timing, the rest are fixed in one position. The Ely.Q could possibly be made to be adjustable with some slight mods. But the Hirobo evo 50 is not adjustable and it flies very accurately as do the Robbes.

[moyesboy]

The 600n phasing has two positions. You can fly it with the drive pins not in the washout base, or with them in the correct place. With the pins out there is approx 30 degrees phase error. Useful if you want to find out what phase error is

[Rotorhead]

....So, we agree there.

What I was referring to was whether the correction angle input via mechanical or electronic means was constant across headspeed.

I dont think it is, from what I've seen of real world results on this; any large changes in headspeed have required re-adjusting the phasing, I've done this on heli's where you can do it mechanically or where you need to use mixes, but both methods have needed re-adjustment.

I'd expect it to be (but may be wrong), hence the correction wouldn't be right at various headspeeds. There's a suggestion (with a reference I need to read), that the mechanical phasing correction deals with this somehow.

As far as the input goes all that matters is what happens above the bottom half of the swash wrt phasing, the rotor head from this point onwards can't tell the orientation of the body of the heli, so I dont see how one method would do it better than the other, I also may be wrong, and would like to know if I am, in any case sometimes you have little choice.

Tx mixing may be better than mechanical mixing really, with mechanical mixing you are also introducing a twist into the linkages, which could throw off your pitch setup, raising or lowering mid stick slightly (only slightly) tx mixing wouldnt do that, so even if its by a small amount that is one thing in tx mixing's favour.

[trillian]

The 600n phasing has two positions. You can fly it with the drive pins not in the washout base, or with them in the correct place. With the pins out there is approx 30 degrees phase error. Useful if you want to find out what phase error is

Yeah, you'd definitely notice the difference of 30 degrees !

What happens with the Ely.Q (Ultimate) swash is that as the swash tilts forward for example, because the inner ring is not on the same horizontal plane as the outer ring, you get a slight phasing change whereby you have less than 90 degrees timing relative to the advancing blade. Conversely as the swash tilts back you have greater than 90 degrees (and obviously this same thing happens with every direction the swash tilts). So it's a tricky one to counter. It is very minor though.

[Rotorhead]

On my helis, only 3 have adjustable swash timing, the rest are fixed in one position. The Ely.Q could possibly be made to be adjustable with some slight mods. But the Hirobo evo 50 is not adjustable and it flies very accurately as do the Robbes.

Yeah the Evo 50 is adjustable you can loosen the block that holds the pins and rotate it, this will adjust the phasing.

[trillian]

Yeah the Evo 50 is adjustable you can loosen the block that holds the pins and rotate it, this will adjust the phasing.

Yep, you're right, my bad. Of my little fleet the Raptors and Trex 450 are not adjustable, the Robbe Futura SEs are not without modding the guide but that is theoretically possible, the Robbe Super Sport is not.

[trillian]

OK, one last thing while on this subject; In Mark's article he says in his experience most helis have needed a mix of up elevator with right aileron / down elevator with left aileron to get a really straight roll.

So if you have an adjustable washout guide would that be the same as moving it slightly to the right (clockwise) ?

Some of this stuff really twists my melon man

[Planehazza]

Already corrected planehazza

So... Just to be certain: it's A not B!

Jk, I hadn't read all the posts when I initially replied. My bad!

[scallybert]

Not so sure on the mechanical vs electronic adjustment answer scallybert. It's just that I understand the adjustments as it was explained to me be a certain Mr Christy Jnr.

Have a read here for more info -> http://www.rcheliaddict.co.uk/setup-...te-timing.html

The only thing I could offer on the mechanical issue is that it has something to do with the fact that the swash plate (i.e. both the inner and outer rings) are still moving in a true elevator and aileron direction with no mixing, and that the phasing adjustment is enacted more purely at the head block rather than lower down the head at the swash plate?

Thanks for the reference; I read the thread.


There seem to be 3 ways of adjusting the phasing:

1. Rotating the top swash relative to the head
2. Rotating the lower swash relative to the heli (Moyesboy).
3. Aileron & elevator mixing

The first two are effectively the same, and seem intuitively 'pure'.

The 3rd way, you're generating the actual heli aileron and elevator inputs as a function of the stick inputs. This is just like when you rotate axes through an angle, by multiplying by a matrix (cos -sin : sin cos) or thereabouts. That calculation of a rotation is 'correct' - not approximate.

The maths aside, it's just like '2'. I agree wth Moyesboy about expo distortion; but, other than that, it seems to me that they all work the same.

Ie I don't think any of them will vary with headspeed. So if '3' needs to be changed with headspeed, so would '1' & '2'.

[Cuppa]

I'm most definately not poking holes in anyones ability to do a propper job (even girls lol) mearly pointing out some possibilitys like i said small errors mechanicly add up! i would allways use a crows foot type swash leveling tool too, mark 1 eyeball can be wrong

[Geek]

Wow what a great thread
Thanks guys

no bun fighting just flying

[rachel]

Wow what a great thread
Thanks guys

no bun fighting just flying

Bunfight !!!!!!!!!!!!!!
Whoop Whoot !!!!!!
Who said Bunfight I am In