Flybar query... Any Clues?

[Steve1M]

Having just replaced my Eco 8 head with some ali bits, I am carefully setting things up.


Sorted out the pitch range, then set up cyclic EPA's to give approx 3-4 degrees each way.


When I ran the head up without blades, just to check for vibrations, I noticed that when applying cyclic, the flybar "disc" angled over an alarming amount despite only having set up cyclic epas as above.(indeed, to reduce the binding at limits, I needed to temper the epas to provide only maybe 2 degrees cyclic!)


It moved so far that, at the limits, something wasn't really happy in the head, causing binding/vibration.
Here is my query:-


Can see from the geometry of the pitch compensator arm that flybar inputs are amplified, probably explaining above, but do these excessive "flybar disc" angles relative to the mainshaft ever actually occur once the main blades are added?


My suspicion is that it does not have chance to, due to the main rotor disc angle following so closely behind, but I cannot tell.
Please comment if you can, as I have no way of telling what will happen in flight, and this binding concerns me.


Many thanks, Steve

[GIXERMAN]

Seems to be a lot of new member joining which is a good thing, proberly better to introduce yourself on a first post, rather than a cry for help straight away. Makes us fill somewhat being used. there are lots of very helpfull guys and girls on here, that are always happy to help.
anyway moving on, welcome to the forum

im not familiar with that model, apart from I no it's old, is it 3 servo ccpm? Or 1 servo 90

[trillian]

If you can post some pics it might be easy to spot anything that is not correct. If the ali bits you have added are not different in function to the bits they replaced, not longer / shorter, shaped differently etc. then it should be fine if it worked properly before.

It's not uncommon for there to be more potential throw of the flybar than what happens in actual practice. I have had one or two where the flybar was physically capable of hitting the canopy but it never moves that far in flight.

Just to add, regarding the pitch compensator arms vs flybar deflection, the geometry should be such that when the swash tilts as far as it can go, the flybar is also deflected to its limits (or just before it reaches the limit by touching the head somewhere). Sometimes there will be an alternate hole for a ball link further inboard on the arms that give the flybar less deflection if you want it more toned-down.

[johnsandywhite]

Hi steve. This might help you with the ECO 8 :- Radd's School of Rotary Flight - Flight Without Online Degrees

[Steve1M]

thanks for the response.... apologies if I seem to have dived in with no introduction.

Set up is 90deg ccpm.

rgds, steve

[Steve1M]

many thanks for your interest and the link.

Trillian.... Your post has put my mind to rest..... mine also would have been capable of intersecting the canopy.

I set up all arms horizontal at 0 degrees.

This heli has had well over 1000 flights, and my cyclic settings have certainly been more than 2 degrees with I suspect no binding in flight, so I am probably concerned about nothing.


Thanks again, Steve

[trillian]

Trillian.... Your post has put my mind to rest..... mine also would have been capable of intersecting the canopy.

Yeah you'll find that what happens in flight is that as the flybar tilts there is pitch being applied to the blade grips and the entire heli starts to tilt in the same direction as well, so there's never a huge difference between the plane of rotation of the flybar vs the rotor disc.

[Jamin_00]

Hi Steve. Glad you seem to be getting the answers you are after.

I wouldnt worry too much about introducing yourself, not everybody does but if you plan on sticking around and want to do an introduction the jump over here and help yourself New Member Intro's

[KevDavies]

3-4 degrees seems not a lot of cyclic??? I run 9* on my Raptor 90

What you have to remember is the flybar is a flight aid and as such it pulls the blades into the correct plane. IF there are no blades present the flybar isnt pulling against anything and will over throw its usual position.

[trillian]

3-4 degrees seems not a lot of cyclic??? I run 9* on my Raptor 90

I thought that as well but I think he means in each direction. I always go for as much as mechanically possible but 6 degrees being the minimum useful amount IMHO, more is better.

[KevDavies]

yeah mine is each direction Sheryl with a total of 18* and +-12.5 on the collective so 25* total collective

[trillian]

yeah mine is each direction Sheryl with a total of 18* and +-12.5 on the collective so 25* total collective

Doh! I think I'm being a numpty. Of course, it needs to be 6 degrees + on the cyclics in both directions, up and down. So yeah 3 or 4 degrees is gonna be really limited. But maybe for scale type flying it's OK

[KevDavies]

I dont think itll have any control authority tbh. Not enough deflection to counteract any external forces. I stand to be corrected tho.

[Jamez]

Blimey, an Eco 8....

[p4ddy]

Blimey, an Eco 8....

Yea Pic please