Gaui CNC head question

[bbagle1]

I bought my hurricane from flying-hobby and it came with a plastic and metal head. I have been using the plastic one but I think I am going to install the metal head soon. I remember reading somewhere about the fixed length liks being the wrong size for proper head geometry. Is this the case or can I just bolt the metal head on and adjust it like I did my plastic one? Thanks

[Happy|Harry]

just bolt it on and fly :D, the person who posted that the links are incorrect and that you need to level the mixing levers at zero pitch was wrong ;)

phil

[mjdee14]

I believe Finless did a video on the metal head and I just went through mine and made ajustments so the bell-hiller arms were level at zero pitch.

I'm not sure at my level of flying it would make any difference but it made sense and was really easy to do....



Mike D

[Vinger]

The mixing levers should not be levelled, otherwise the geometry for positive and negative pitch will not be the same plus you will get weird mixing results. The mixing levers should be 90 deg to the link from the swashplate. Even Finless had this wrong in his build videos. :arggg:

[Happy|Harry]

I believe Finless did a video on the metal head and I just went through mine and made ajustments so the bell-hiller arms were level at zero pitch.

I'm not sure at my level of flying it would make any difference but it made sense and was really easy to do....



Mike D

yes he did, and like i said he was wrong ;). Vinger thank god someone else see the light lol :D

phil

[bugdozer]

...The mixing levers should be 90 deg to the link from the swashplate.

Thank you VInger, I knew there had to be a reason for it. I couldn't imagine Gaui designing in an alignment issue just because they have one link too long. :thumbup:

[bbagle1]

So i can leave it stock and not worry about it? All the geometry is fine?

[Helibelly]

Hi, I wonder has anybody noticed a difference between the "Gaui method" and the "Finless method" in actual flying conditions or pitch plus and minus or interactions on the bench?.
I set up mine the Finless way, although I thought it strange that Gaui would have gotten this wrong, after all they designed the heli. I must admit though that I can't see any difference with the pitch gauge between plus and minus readings. Perhaps I am missing some thing? I would love to know which way is really best and why, even though my limited flying style may not notice it.
Eric.

[bugdozer]

I flew this morning set up the Bob way but I have changed it back over to the Gaui way this afternoon. I don't see any changes in the full pitch angles and if it's not raining in the morning, I'll go flying.

[mjdee14]

I flew mine this afternoon Bob's way and didn't notice any major difference...i also looked at several of the larger heli on-line instruction manuals...although they don't really spell it out...several show the bell-hiller arm perpendicular to the main shaft..

I too would like to know the best set up...

Both theories make sense....90 deg to the rod from the swash...or all arms level and perp to the main shaft....

Anyone have any data to back it up...? could find nothing on the web.

[Mikej]

Good question - I was also wondering the same as I went with Bob's suggestion and I am VERY happy with how it flys.

<warning - this is based upon an understanding of geometry not heli experience>
From my understanding of geometry the difference with the "Bob method" is that around 0 degrees the movements either side of 0 will not be completely balanced as it would be with a 90 degree angle.

However on my (non-3D) pitch curve set-up I think this will be masked somewhat (as around 0 degrees my pitch curve is not straight anyway) and I am not good enough to notice - a good 3D-er may notice that the heli is more responsive around 0 inverted than it is upright. There again - I'm not sure if it is that precise a "science" as things such as wind affect us all of the time anyway, and I'm not sure that anyone flys much arond 0 anyway - the movements would still be imbalanced further away from 0 but less pronouncedly.
<end of warning>

Am I right :thumbup: or is it :bs ??

Mike.

[Vinger]

Guys/Girls,

My understanding of geometry and the way helicopter heads are controlled, with the mixing lever levelled one would be hard pressed to feel a differrence in pitch, but the mixing ratio between the flybar (remember we control this only in cyclic) and the main blades will definately be differrent for pushing or pulling on the link between the flybar and mixing levers. As was posted earlier, with a linear pitch curve, the response to positive and negative pitch will also be differrent.

I just sat for more than an hour adjusting only one mixing lever level and leaving the other one 90 deg to the link, then putting a pitch gauge on each blade and measuring the pitch angle on both at the same time, while changing pitch with a linear pitch curve set in the TX. The pitch change is definately linear with the mixing arms 90 deg to the link, where the level lever's main blade was not linear in it's pitch change.

Now if we add the mixing of the flybar to the equation then the blade with the lever level goes completely out of synch with the simaltaneous input of elevator (fore/aft cyclic), aileron (left/right cyclic) and a collective pitch change.:thumbdown:

Do this and one will immediately see that the best geometric setup of these mxing levers is definately the way GAI has done it ie mixing levers 90 deg to swashplate input link.

One good thing from all this is that I redid my head setup completely and it now flies like new again.:happyd

[bugdozer]

Thanks again Vinger for the information, and admit it, you enjoyed experimenting, didn't you. :) One of the great things about helis is the endless tinkering. It's raining right now so no flying but I can still tinker. Thanks again. :thumbup:

[Mikej]

Vinger,

Thanks for that - it's good to know that the empirical testing supports the theory. All I need to do now is get brave enough to change it when I am happy with the way it flys currently.

Cheers,
Mike.

[istandalone]

i'm a compete moron when it comes to what exaclty is a mixing lever and the swash input link. could someone maybe post a pic with these two components highlighted? my manual get destroyed so that's out, even if it is in there. thanks.

[Happy|Harry]

istandalone here's a pic from another birds manual (Hurrican 50) so the link lengths are not to be used on the hurricane 550, but you can clearly see here what myself and vinger are talking about :)

phil

[mjdee14]

istandalone here's a pic from another birds manual (Hurrican 50) so the link lengths are not to be used on the hurricane 550, but you can clearly see here what myself and vinger are talking about :)

phil

HH...thanks for the picture...I could not find anything that showed it that way....it makes sense....so back to the original I will go.

Thanks, again.

Mike D

[istandalone]

thanks guys!!

[istandalone]

the only problem i noticed with that picture is this. it says "the linkage rod coming from the swash MUST be 90' to the mixer arm. if not there will be different angles from positive pitch to negative"
in the pic, the angle is greater then 90. i really hope this is to show how it isn't supposed to be, rather then the directions being wrong.

[Happy|Harry]

the washout arm's aren't level in the picture either ;), but we're not following the picture it's the directions that are important, and they are correct regarding the angles required for all areas and if you think about why it needs to be 90º for the swash link to get linear pitch from positive to negative you will clearly see why :)

phil