Any one reversed rotation on an Align quad blade head?

[FiveZigen]

Hey Guys, I was just working on a project I had on hold while I was away for the summer and ran into a small issue. I am trying to reverse the main rotor direction on a trex500 I am putting into a 105 so that it matches the full scale. I have done this in the past with no problems on other projects. Unfortunately it appears that because of the design of the align four blade head this is not possible with out changing to a smaller set of swash lock arms (even with I have a feeling this will limit my range over the stock long arms). I was wondering if any one had encountered this before, and could possibly help point me in the right direction.
I will probably just run it CW (stock) and have the tail rotor on the correct scale side pulling instead of pushing if I can't come up with a way to reverse the head as well.

Thanks in advance

Ryan

[FerretMaster]

I will ask the really stupid question.....Why not just run it in the opposite direction? There are plenty of "following arm" heads out there that work very well.Looking at my 500 size Align 4 blade head I see no problem running it "in reverse" as there seem to be no directionally sensitive components.




P.S. You try it first and let the rest of us know!!

[FiveZigen]

I got it to work. I modified some mixing arms and used the short side flipped over with the plastic component of the arm flipped as well. When you reverse the direction of the head you need to have the plastic arms face the other way as well or they interact with the links hence why I needed to make the shorter arms.
Pic 1-2) Here is the stock quad blade arm on the left, stock swash lock arm from FB Trex500 and the same arm cut down to the useable piece I need.

Pic 3) After paint, I put new bearings in as well.

Pic 4) Finished, You may need to clearance the plastic swash arms, as they may interact with the links.

[FiveZigen]

If you were to simply spin the head backwards, because the phasing is mechanically set and not adjustable on this head the phasing would now be off. Try it for your selves and you will see what I mean.
Here is the pic of how it looks stock

You see how if we spin it in the reverse direction the swash plate will now be 90 degrees behind the direction of travel instead of in front where it is suppose to be? You can't take the link off the swash and move it to the correct ball at 90 degrees ahead of the blade with out it interfering with the swash lock arm. If the washout was not part of the head you could simply flip the plastic arm and adjust the washout base so everything is cool. With this head flipping the plastic arm just has the bottom hole sticking out into space. You need some way to flip the metal arms as well to get everything jiving, which I have done above.

[FerretMaster]

OKAY!!

Good answer!

[zeeflyboy]

actually the phasing would be fine, just reversed. The fact that you would now be running trailing edge however means inputs are also reversed - end result, everything works out. Just look at that picture above, imagine you put a left aileron command in... swash tilts left. blade with the link on the left side will currently be over the tail boom, grip in the downwards position increasing pitch. Gyroscopic precession translates this 90 degrees further round in the direction of rotation ending in a force lifting the right side of the disc - a left turn just as commanded.

The only peculiarity would be that due to the trailing edge control, the swash moving up would result in negative pitch and vice versa so one would just have to be careful during setup.

On a rigid head with no dampers like this, there is no real disadvantage or difference to trailing grip vs leading grip as far as I am aware.

Anyway, you've got it to work but just thought I'd point that out

[cobieg]

Ok, so this question was asked to me recently if the scale bird that I am building will have the blades running reversed.
I have the tail reversed to the port side. So I am thinking about it.
I guess swap the plugs for pitch and aileron on the FBL?
Flip the blade grips for leading edge control. Main and tail.
Of course flip the one way brng.
Anything else?

Oh yeah, this is a 2 blade for now.

[goodhunting]

You do not swap the plugs in the FBL. You set that up in the software. Depending on your FBL controller....

Gh

[cobieg]

Or, does it really matter what way the blades rotate for pitch and aileron on a 2 blade head?

[Keyrigger]

In some cases, there is a box in the software tabs where you choose the direction of rotation of the head. If there is no place for it, I would not worry about it. As to the two servos, pitch and aileron, I have seen a few instances where newbie builders have switched them going to the gyro/receiver and there was no consequence. As long as the directions of the three servos is correct, not many are fussy as to what is where. It would take a full page to describe what I did to mine and it still worked just fine. I know the Skookum has the option for counter clockwise rotation and I am sure there are more that do. The most important thing is to make sure the head is set for opposite rotation. Take care.

Don

[PhoenixNOTAR]

Don, the only reason a fbl system wants to know the main Rotor direction is so it can apply the correct anti torque direction to the tail Rotor when collective pitch is increased or decreased.

Sandy

[Keyrigger]

Hi Sandy:

Yes, it certainly does make sense why the software needs to know it. It is not something that is in every one of the gyros that I have set up and got running. The one and only time I set a standard tail gyro for clockwise rotation, there was nothing like that to choose but if you set the direction of compensation for heading hold or rate, it worked like a charm. Thanks and see you soon.

Don