Re: Elevator balance check.

Christian Bailey <aetm12@...>

I searched and found this thread because my Berkut is in paint and the A&P
who is balancing the control surfaces asked for more detailed instructions
on limits – both for Elevator and Ailerons.

I understand that, like for the LongEZ, the elevator must balance trailing
edge up (as measured on bottom surface) when supported at the hinge rod. And
ailerons must balance between upper surface level and bottom surface level.

But the A&P has some follow-up questions:

1) Usually there is a tolerance range in inch pounds?

2) Are there limits on how much weight you can add if possible?
From the Canard Pusher helpfully linked by Andy, I have: “any Roncz
elevator, (after it has been balanced to the pivot line) that weighs more
than 3.8 lb (left) and 3.4 lb (right) should not be flown” and “if you have
to add weight, it MUST be added only to the outboard mass balance.”
I didn’t find anything for the ailerons, but assume that less weight is
needed for them so it’s not practically an issue.

3) Is there a defined limit to how trailing edge up elevators can or should
be? (As there is for the ailerons.)
From the CP, I have: “balance … elevators to at least the pivot axis, or
forward of it, after paint, and flight ready.”

Do I have all that right and is there anything else you would add?

Thank you,

Berkut 540 N6212

From: <> On
Behalf Of Andy Amendala [canard-aviators]
Sent: Monday, December 21, 2015 8:35 PM
To: Kevin Kelly <>; Canard Aviators Mailing List
Subject: RE: [c-a] Elevator balance check.

Merry Christmas Kevin -
Indeed there is.  RAF published an alternative procedure for checking the
static balance of Roncz canard elevators due to their slightly different
geometry than the GU elevators.
See Page 4 of CP 108 which you can read here:
[link removed because Yahoo Groups was flagging the message]
This assumes you have fabricated two knife-edge surfaces that can be easily
leveled.  I recommend hot-gluing a hacksaw blade onto a piece of wood with
the narrow edge facing up (make two).  See the following link for a picture
of what I built - took about 30 minutes.  Notice the devices are tall enough
to allow the elevator to flip completely over without the belhorns or
balance weights hitting the table.

Here's the process: 

1.  Assemble each elevator with all appropriate hardware as if it was a
finished elevator.  Be sure to bolt on the spool piece if checking the left
elevator - it's trim belhorn affects the static balance so it should be
present when you check it.  Insert the hinge pin to its installed depth.
2.  Set the knife edge devices you made on the table, parallel to each other
and wide enough to span the elevator.  On the left knife edge, rest the
hinge pin, on the right, rest the torque tube.
3.  Flip the elevator over so the bottom skin faces the ceiling and is level
(use a dial indicator).  Do not leave the dial indicator on the elevator,
just use it to find 0 degrees/level.  The elevator will not want to stay in
this position (or at least it shouldn't), so you'll need to hold it.
4.  Let go of the elevator.  It should immediately move to flip its trailing
edge toward the sky or at the worst case, stay absolutely still and level. 
If the elevator demonstrates *any* tendency for its trailing edge to fall
toward the ground, the elevator has failed its static balance check and
needs work.
Drop me a note if you want a video or pictures of all of the above.  I've
recorded it all in my build log.  Be sure to repeat the above process after
any work is done to the elevators (filling, sanding, painting, priming), you
name it.  They are very sensitive and balance changes rapidly.
Andy Amendala
Date: Mon, 21 Dec 2015 12:47:53 +0000
Subject: [c-a] Elevator balance check.

The plans (chapter 11) describe an arrangement to hang elevators by the
pivot on a GU canard upside down to check balance. Given that the pivot
arrangement on the Roncz canard is different is there a way to check them???

Thanks and Happy Christmas 

Kevin Kelly

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