[rebel-builders] heavy wing solution

[kevin curtis]

I have a kit started by someone else. The ailerons are done, two inners and two outers, no markings, what's the differance?

--- On Mon, 7/4/11, Ron Shannon <rshannon@cruzcom.com> wrote:


From: Ron Shannon <rshannon@cruzcom.com>
Subject: [rebel-builders] heavy wing solution
To: rebel-builders@dcsol.com
Date: Monday, July 4, 2011, 7:42 PM


Fabulous CAVU flight here today, lolling about at 7500 ft. overlooking
the snowy Olympic Mtns. to the south. We don't get a whole lot of
these days in the Pacific NW, and really appreciate them when we do.

The best part was that after switching the outer left flaperon section
with the inner right one, 254R now flies hands (and feet) off for
25-30 seconds at a time, perfectly trimmed. The right wing was always
a little heavy before, probably because the flaperon sections had
gotten mixed up at some point since the original builder did the
skeletons, and aligned them and their horns in pairs, of course.
Naturally, I had put off making this change for a long time because,
as anyone who's done it knows, taking them off and on again is an
onerous task, and I had planned to leave it until disassembly for
painting. Well, painting has been delayed, but not Oshkosh, and a
multi-day cross country with a heavy wing is at best, suboptimal.

There were two clues to the cause of the heavy right wing. First, the
two flaperon sections that were slightly lower ( ~ 3/16") than others
were the outboard section on the left, and the inboard section on the
right. The theory was the left wing had more lift due to the greater
arm, or leverage, of the extra lift from the lower, left outboard
section. Second, in reflex it flew hands off level anyway. Thus the
corollary to the first theory was that in reflex the mis-matched
flaperon sections were less "in play", making the slightly greater
lift on the left insignificant. I wouldn't be surprised if the
flaperon sections were properly marked in matched pairs to begin with,
but the banana brain novice who took over the project never noticed.
That would be me, of course, but it's all better now.

So the moral of the story is A) keep your pairs marked and identified
along the way (Duh!), and B) if you take over a project make sure you
know what pairs up with what (not quite such a Duh!)

Ron

PS - The A/P roll servo needs some minor gain & response adjustments
which I didn't want to do on a first flight, but it's working well
too, whether by itself, or driven by the GPS, or by the EFIS. Another
flight or two and the dynamics should be tuned up. More on that when
the pitch servo is in.



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[Ron Shannon]

There is really no difference between the four, except two have a horn
on the right and two have a horn on the left. Looking forward, a horn
on the right can only go outboard left wing or inboard right wing. A
horn on the left can only go inboard left wing or outboard right wing.

That being said, when they are built the horns are mounted and aligned
in pairs, i.e., per wing, using, of course, one right horn and one
left horn. One pair (right+left) may be ever so slightly different
compared to the other pair, merely because, I guess, they're done
separate from the other pair. Should each wing's set (one right & one
left horn) have different angles from the set for the other wing? No,
or not much, but it happens.

The difference here was really quite subtle. It was obvious enough
that when assembling I hadn't paired them up properly, and fixing that
obviously needed to be done. Whether fixing the pairing was going to
solve my heavy right wing trim or not was the unknown.

Ron


On Mon, Jul 4, 2011 at 7:32 PM, kevin curtis <kcs1911@yahoo.com> wrote:

I have a kit started by someone else. The ailerons are done, two inners and two outers, no markings, what's the differance?

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[Ron Shannon]

To answer your question a little more directly, you may not be able to
tell what the proper pairing should be without mounting them on the
wings and seeing how they match up. I suppose you _might_ be able to
tell by laying them on a flat surface, end-to-end, with the horns next
to each other, and seeing which pairing of horns matches best. But the
differences, if any, that are visible at the horns, with their
relatively small diameter from the center of rotation, might not be
enough to show a difference further out at the trailing edges.

On the bright side, there are only two combinations to check. Perhaps
more importantly, with a little luck the horn angles on all four of
yours may be close enough that whichever of the two choices of pairing
you pick won't even matter anyway. In a perfect world, it would always
be so. ;-)

Ron



On Mon, Jul 4, 2011 at 8:29 PM, Ron Shannon <rshannon@cruzcom.com> wrote:

There is really no difference between the four, except two have a horn
on the right and two have a horn on the left. Looking forward, a horn
on the right can only go outboard left wing or inboard right wing. A
horn on the left can only go inboard left wing or outboard right wing.

That being said, when they are built the horns are mounted and aligned
in pairs, i.e., per wing, using, of course, one right horn and one
left horn. One pair (right+left) may be ever so slightly different
compared to the other pair, merely because, I guess, they're done
separate from the other pair. Should each wing's set (one right & one
left horn) have different angles from the set for the other wing? No,
or not much, but it happens.

The difference here was really quite subtle. It was obvious enough
that when assembling I hadn't paired them up properly, and fixing that
obviously needed to be done. Whether fixing the pairing was going to
solve my heavy right wing trim or not was the unknown.

Ron


On Mon, Jul 4, 2011 at 7:32 PM, kevin curtis <kcs1911@yahoo.com> wrote:

I have a kit started by someone else. The ailerons are done, two inners and two outers, no markings, what's the differance?

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