Mini V-Bar with T-Rex 550 Cyclic Ring Question

Just got a Mini V-Bar for my T-Rex 550. Everything's already setup but I find my elevator servo binding at full throw even when at mid stick. I have to lower the cyclic ring to 55% in order for it not to bind.

Is it okay to leave the Cyclic Ring at 55%. Will this actually affect my flip and roll rates?

On hindsight, if it the servo did not bind at at cyclic ring setting of 85% the throw of the elevator would be something like 14 or 15 degrees which seems pretty ridiculous.

Anybody encounter anything like this? Any advice will be greatly appreciated. Thanks.

CR of 55 is far too low.

About your 14 deg - thats not the throw in flight depending on your stick position. You could not measure this on the bench.

Use our 8 deg. setup and set CR to avoid binding at approx. hovering collective and full aileron+elevator (check only in setup mode).

But ... if you won't get more than 55 the heli seems to have a geometry that needs some improvements. Can you attach a image of the whole heli (incl. head) and the setup file?

regards (EN) / Gruss (DE)

Rainer Vetter

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Posting and answering - please use a PC and a standard keyboard. Answer all questions fully, take the needed time, don't forget probably requested attachments.

Für Posts und Antworten bitte einen PC und eine richtige Taststaur benutzen sowie alle Fragen vollständig abarbeiten. Nehmt Euch Zeit, beantwortet Rückfragen in Ruhe und vollständig.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Für Einzelkommunikation bitte ausschließlich Email verwenden! - PN, Messenger, Chat usw. werden nicht bearbeitet.
For single user communication please send a email only! PM, Messenger, Chat etc. won't be read.

CR of my AVANT is set at 55%, too. In my case, the bottom inner side of the swash touches the main shaft at over 55%, so I have to keep this low value..

Though she flies greatly, I'm sure there must be something nice I have missed at 55%.

Collective = +- 11 degree Cyclic = 8
Distance from the center of the servo to hole of the servo horn is 10.00mm(the closest one)

RV Wrote:
-------------------------------------------------------
> CR of 55 is far too low.
>
> About your 14 deg - thats not the throw in flight
> depending on your stick position. You could not
> measure this on the bench.
>
> Use our 8 deg. setup and set CR to avoid binding
> at approx. hovering collective and full
> aileron+elevator (check only in setup mode).
>
> But ... if you won't get more than 55 the heli
> seems to have a geometry that needs some
> improvements. Can you attach a image of the whole
> heli (incl. head) and the setup file?

Hi Rainer,

My cyclic is already set to 8 deg. as per the instructions. The value I got was 75. Anyway, I managed to increase the CR to 75 after grinding off a part of the anti-rotation bracket. The servo arms would hit it at full elevator throw even at mid stick (as seen in pic 2). That's wats causing the binding. I've attached some photos of the head as well as my setup file.

Let me know what you think.

Hmmmm.....

Could you use a longer servo horn? - I think there is 1 hole left ...

regards (EN) / Gruss (DE)

Rainer Vetter

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Posting and answering - please use a PC and a standard keyboard. Answer all questions fully, take the needed time, don't forget probably requested attachments.

Für Posts und Antworten bitte einen PC und eine richtige Taststaur benutzen sowie alle Fragen vollständig abarbeiten. Nehmt Euch Zeit, beantwortet Rückfragen in Ruhe und vollständig.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Für Einzelkommunikation bitte ausschließlich Email verwenden! - PN, Messenger, Chat usw. werden nicht bearbeitet.
For single user communication please send a email only! PM, Messenger, Chat etc. won't be read.

Wouldn't a longer horn increase the throw and decrease the resolution, making it bind more? I would think I would need a shorter horn decrease the throw...

HI There

I have just finished a T-Rex 600 Esp conversion to FBL with the Align head.

Its basically a 550 although it should be easier to setup on the 550 as the 600 was never "exactly perfect" for FBL.

I too had the same issue, you Can do it though it actually went really nice- lost loads of arms and levers and made it direct servo to swash like the 550E.

I have :

8deg Cyclic set in V bar.
75 CR
Cyclic 80
Collective 82

Perfect no binds DS610 servos. +- 13 Deg Pitch.
Using Quick UK Ally Arms for 550E FBL from Fast Lads. Use the Inner hole Closest to the Center.

James

Just maiden the bird today with the mini. Flies perfect!! Currently I managed to put in CR 75, 8 Deg. Cyclic (75 value) & 13 deg. Collective (85 value) at setup. Everything's working great!! Thanks for all the guys who responded to my questions.

Support from mikado is tops as always!!

I never really understood the CR settings. According to the instructions how to set the CR value, is to have the pitch (throttle stick) at about hover position and than give full ELE and AILE. I can do this with CR set to 82 without binding. When however I go only full ELEV with that set up the ELEV servo arm starts binding little bellow hover position of the throttle stick. As soon as I ad AILE input the CR somehow kicks in and lovers the ELE arm, so the binding is not an issue than. So, I have my CR set to 82 and have not experienced any issues in flight. All works well.

Hi.

To shed some light on the CR:

First of all, it's not a ring, it's a double-truncated cone.
So, the more collective you add, the more the CR reduces cyclic travel.

When setting the CR in setup mode, you do not have the control loop active.
When checking in flight mode, the servos might do more travel then they will *ever* do in flight since the heli doesn't react to the control loop, the control loop is open. E. g. the roll or flip rate is limited naturally so the control loop won't oversteer in the air (where it has a feedback from the moving sensors).

In a full collective move, it's rather uncommon to bang the cyclic stick, even more so since even the hottest setup would certainly bog.

So, when you do the setup as instructed, AND when the other setup steps are within the given range of values (collective, cyclic), you are practically safe. Even if you can cause a situation where the mechanics would bind when on the ground.

There is no "hard limit" to the servo travels since this would affect flight behaviour badly, we (read like: you ) want to get our geometry right so everyhing works best.

— Eddi

Born to fly ...
forced to work.