Finless just confused me on mixer arm ball location

[zguy]

Just watched the Finless build video on head setup and am now confused on mixer arm ball location. :confused:

My goal is maximum agility and I now have the balls on the inner hole on the short side and the lower-inner hole on the long side. This seemed to match the manual, but I downloaded a newer manual and the pics have been changed.

Finless did mention in the video that he spoke to Sean on this. Can someone (Sean?) please verify the proper locations and give a understanding of how the geometry works?

Thanks!

[Mercuriell]

I put mine on the lower inner hole as per manual and believe me it is plenty agile :shock: - Shawn has a note on this http://www.helifreak.com/showthread.php?t=45267

[zguy]

I put mine on the lower inner hole as per manual and believe me it is plenty agile :shock: - Shawn has a note on this http://www.helifreak.com/showthread.php?t=45267

Thanks, but I think this was regarding the direction that the arm mounts to the grip and not the ball placement. Finless put the ball on the long arm in the upper outer hole and claims this is for maximum agility.

Still confused :confused:

[BruceW]

I put mine in the lower-inner hole on the long part of the arm also but inner part of the short arm is the same as Bob. Tonight I'll move it to the upper-outer hole and see if I notice a difference in cyclic response. It looks like all the link arms are still the same length in this orientation so it shouldn't affect pitch setup, right?

[OICU812]

I knew this was going to get people talking! LOL, I spoke with Bob over the phone about this. I can not say myself which would be better, I have always done it by the manual, On my flybared 500s the bottom left is my hole as well as inside on the short, I have tons of cyclic response and speed on the head without issue. As I said to Bob I have bnever tried the other holes or felt the need to is all. I don't think the delta difference will be felt in flight myself, as I also stated to Bob I have never felt anything weird by doing the stock hole suggestions.

[BruceW]

Alright, then I'll just leave it the way it is.

[zguy]

Thanks for the replies, but does not sound like a definitive answer. :confused:
Bruce, if you have the time to test it I'd love to hear the results.

Was hoping that someone understands the geometry and could explain it to the rest of us.

[OICU812]

I flown all my Logos from back to the Logo 10 in this mixer orientation, definitive enough for me.

[Mercuriell]

Thanks for the replies, but does not sound like a definitive answer. :confused:
Bruce, if you have the time to test it I'd love to hear the results.

Was hoping that someone understands the geometry and could explain it to the rest of us.

I suspect that using any hole not going to make any noticeable difference - up or down hole offsets the delta to a tiny degree as they are located above and below the hingle and short arm line.

Using the inner or outer ball affects the Bell-Hiller mixing ratio ie how much swashplate movement is transmittted direct to the blades (Bell) and how much indirectly via the flybar (Hiller) - using the inner ball increases the Flybar (Hiller) component compared to swashplate component and would thus slow roll rates a tad.

So as far as I understand it using the outer hole will marginally increase roll rates (although other factors such as cyclic range, HS, and paddle weight and geometry will probably affect it more.) Using the upper or lower hole can't see it making any appreciable difference ! Still puzzled why Bob and Shaun chose to go against the manual advice and use the outer rather than the inner hole on the long arm!

Good treatise on how the Bell Hiller system works: (http://www.w3mh.co.uk/articles/html/csm9-11.htm)

Nice article on heli set up (http://www.natew.com/rcheli/frame_main.cgi/html.FullSetup)

[OICU812]

Ok lets be clear, my setups are to the manual, my ball is located lower left not upper right. Bob wanted to do his that way, and that is perfectly fine, I highly doubt there is any different effect.

[Mercuriell]

Ok lets be clear, my setups are to the manual, my ball is located lower left not upper right. Bob wanted to do his that way, and that is perfectly fine, I highly doubt there is any different effect.

I agree with that :) - Just out of interest what effect did Bob think it might have moving the ball out and up ?

[OICU812]

I agree with that :) - Just out of interest what effect did Bob think it might have moving the ball out and up ?


Just less delta on the leading grip.

[Funflyer]

Ok lets be clear, my setups are to the manual, my ball is located lower left not upper right. Bob wanted to do his that way, and that is perfectly fine, I highly doubt there is any different effect.

I'm building my 500 3D and initially followed Bob's recommendation for the ball in the top right hole. However I was having trouble getting equal positive and negative pitch. I had about 1.5 degrees more of negative pitch. I changed the ball to the inner left hole and that helped my pitch discrepancy. I now have +12 and ~ -12.5, but my mixer arms aren't level like they were with Bob's ball location. Did I do something wrong? I can't see any other way to make the mixer arms more level and I don't see how you can shift the pitch range to get equal positive and negative without deviating from 0 pitch at center stick. Maybe I'm being too much of a perfectionist? :roll:

[OICU812]

they way you have it is good, no woory...

[helicraze]

I found that if you measure the pitch with the flybar parralell to the surface the skids are resting on you will not get proper pitch reading.

You must measure your pitch with the flybar parralell to the tail boom (best reference) as the main body is angled forwards when resting flat on the skids.
It is critical as unlike the raptor the flybar mix ratio is not 1:1.

[Funflyer]

I found that if you measure the pitch with the flybar parralell to the surface the skids are resting on you will not get proper pitch reading.

You must measure your pitch with the flybar parralell to the tail boom (best reference) as the main body is angled forwards when resting flat on the skids.
It is critical as unlike the raptor the flybar mix ratio is not 1:1.

You're exactly right. I used a level and proped up the heli so the main shaft was vertical before doing any adjustments. I also found that my elevator servo link needed to be 1mm longer than the aileron servos to get the swash level. I didn't use the servo grommets, just washers to hard mount my servos and the elevator servo is probably just sitting a little lower in the frame. Even after all that meticulousness, I still couldn't get the exact same positive and negative pitch. My name is Funflyer and I am a habitual perfectionist. :o

But it sounds like it's close enough so I'll fly it as is, my meager skills won't notice anyway, especially since I can only fly inverted for about a second at a time. :oops:

[Funflyer]

Well I figured out what part of my problem was when I went to tighten the tail boom. Apparently when I put the head assembly on the shaft the collar slipped and the main shaft was drooping by about 10mm. I didn't notice it until I saw that the tail belt was running high on the pulley. :Slap

So I cleaned the main shaft with some alcohol (I think some oil got under the collar from the bearing) and reinstalled the collar with a tiny bit of loctite on the shaft just for extra gripping strength. When I redid all the links it is now closer to equal positive and negative pitch and the mixer arms are more level, but not straight horizontal. Good enough.