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MauleDriver(at)nc.rr.com
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 Posted: Thu Feb 07, 2008 3:50 pm Post subject: Elevator trim - 35 degree up and asymmetric geometry |
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I just installed the trim servo and am playing with the trim setup. The
cable geometry dictates that the tabs will not move together. The
right hand elevator moves through a much greater arc than the left. A
fact that is probably less noticeable with the rudder in place.
However, when I adjust the clevises and the Rivethead bracket to get 35
degrees of deflection at the full up trim position, I find that I am at
the maximum physical deflection of the tab itself (not a problem, just
an acceptable coincidence).
More noteworthy, I find that with both the left and right hand elevator
tabs adjusted to 35 degrees full up at one end of the servo's travel,
going to the full down trim position results in the right elevator tab
moving to a roughly 20 degree deflection while the left elevator tab is
at zero deflection. In fact, the last few mm of servo movement result
in the left tab deflecting very slightly in the opposite direction.
None of this is inconsistent with the asymmetric geometry of the whole
setup but just want some warm fuzzies that others are experienced
something similar. (If this is in the archives, I just can't find it).
Bill "there's a good bit of trim drag in here somewhere" Watson
40605
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jesse(at)saintaviation.co
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| Posted: Thu Feb 07, 2008 4:55 pm Post subject: Elevator trim - 35 degree up and asymmetric geometry |
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That is how it is supposed to be. It should end up so when the right
hits the neutral position the left should as well, then the left will
more or less stay there and the right will continue. When light you
need a lot of nose-up trim, but Van's didn't want (I assume) to give
as much possibility for nose-down trim in the case of runaway trim.
do not archive
Jesse Saint
Saint Aviation, Inc.
jesse(at)saintaviation.com
Cell: 352-427-0285
Fax: 815-377-3694
On Feb 7, 2008, at 6:44 PM, MauleDriver wrote:
| Quote: |
I just installed the trim servo and am playing with the trim setup.
The cable geometry dictates that the tabs will not move together.
The right hand elevator moves through a much greater arc than the
left. A fact that is probably less noticeable with the rudder in
place.
However, when I adjust the clevises and the Rivethead bracket to get
35 degrees of deflection at the full up trim position, I find that I
am at the maximum physical deflection of the tab itself (not a
problem, just an acceptable coincidence).
More noteworthy, I find that with both the left and right hand
elevator tabs adjusted to 35 degrees full up at one end of the
servo's travel, going to the full down trim position results in the
right elevator tab moving to a roughly 20 degree deflection while
the left elevator tab is at zero deflection. In fact, the last few
mm of servo movement result in the left tab deflecting very slightly
in the opposite direction.
None of this is inconsistent with the asymmetric geometry of the
whole setup but just want some warm fuzzies that others are
experienced something similar. (If this is in the archives, I just
can't find it).
Bill "there's a good bit of trim drag in here somewhere" Watson
40605
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Tim Olson
Joined: 25 Jan 2007
Posts: 2882
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| Posted: Thu Feb 07, 2008 5:18 pm Post subject: Elevator trim - 35 degree up and asymmetric geometry |
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As Jesse said....yup, that's the way it should be. Works well.
Tim Olson - RV-10 N104CD - Flying
do not archive
MauleDriver wrote:
| Quote: |
I just installed the trim servo and am playing with the trim setup. The
cable geometry dictates that the tabs will not move together. The
right hand elevator moves through a much greater arc than the left. A
fact that is probably less noticeable with the rudder in place.
However, when I adjust the clevises and the Rivethead bracket to get 35
degrees of deflection at the full up trim position, I find that I am at
the maximum physical deflection of the tab itself (not a problem, just
an acceptable coincidence).
More noteworthy, I find that with both the left and right hand elevator
tabs adjusted to 35 degrees full up at one end of the servo's travel,
going to the full down trim position results in the right elevator tab
moving to a roughly 20 degree deflection while the left elevator tab is
at zero deflection. In fact, the last few mm of servo movement result
in the left tab deflecting very slightly in the opposite direction.
None of this is inconsistent with the asymmetric geometry of the whole
setup but just want some warm fuzzies that others are experienced
something similar. (If this is in the archives, I just can't find it).
Bill "there's a good bit of trim drag in here somewhere" Watson
40605
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MauleDriver(at)nc.rr.com
Guest
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| Posted: Thu Feb 07, 2008 6:07 pm Post subject: Elevator trim - 35 degree up and asymmetric geometry |
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I'm all fuzzy now and moving on. Thanks!
Jesse Saint wrote:
| Quote: |
That is how it is supposed to be. It should end up so when the right
hits the neutral position the left should as well, then the left will
more or less stay there and the right will continue. When light you
need a lot of nose-up trim, but Van's didn't want (I assume) to give
as much possibility for nose-down trim in the case of runaway trim.
do not archive
Jesse Saint
Saint Aviation, Inc.
jesse(at)saintaviation.com
Cell: 352-427-0285
Fax: 815-377-3694
On Feb 7, 2008, at 6:44 PM, MauleDriver wrote:
>
>
> I just installed the trim servo and am playing with the trim setup.
> The cable geometry dictates that the tabs will not move together.
> The right hand elevator moves through a much greater arc than the
> left. A fact that is probably less noticeable with the rudder in place.
> However, when I adjust the clevises and the Rivethead bracket to get
> 35 degrees of deflection at the full up trim position, I find that I
> am at the maximum physical deflection of the tab itself (not a
> problem, just an acceptable coincidence).
> More noteworthy, I find that with both the left and right hand
> elevator tabs adjusted to 35 degrees full up at one end of the
> servo's travel, going to the full down trim position results in the
> right elevator tab moving to a roughly 20 degree deflection while the
> left elevator tab is at zero deflection. In fact, the last few mm of
> servo movement result in the left tab deflecting very slightly in the
> opposite direction.
>
> None of this is inconsistent with the asymmetric geometry of the
> whole setup but just want some warm fuzzies that others are
> experienced something similar. (If this is in the archives, I just
> can't find it).
>
> Bill "there's a good bit of trim drag in here somewhere" Watson
> 40605
>
>
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Jack.Phillips(at)cardinal
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| Posted: Fri Feb 08, 2008 4:18 am Post subject: Elevator trim - 35 degree up and asymmetric geometry |
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I'm glad to hear this. I had noticed the same thing and went through
the plans three times to make sure I hadn't screwed anything up. With
the elevators tied together it shouldn't matter if it's asymmetrical,
but it just looked a little odd.
Jack Phillips
#40610
Still waiting for the Wing Kit to arrive
--
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billderou(at)yahoo.com
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| Posted: Fri Feb 08, 2008 10:22 am Post subject: Elevator trim - 35 degree up and asymmetric geometry |
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It will matter when you are cruising with a load and need down trim and one elevator trim is slightly down and the other is slightly up. Suggest you search on my old post entitied "twisted tail".
Bill DeRouchey
N939SB
"Phillips, Jack" <Jack.Phillips(at)cardinalhealth.com> wrote:
[quote]--> RV10-List message posted by: "Phillips, Jack"
I'm glad to hear this. I had noticed the same thing and went through
the plans three times to make sure I hadn't screwed anything up. With
the elevators tied together it shouldn't matter if it's asymmetrical,
but it just looked a little odd.
Jack Phillips
#40610
Still waiting for the Wing Kit to arrive
--
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Lew Gallagher
Joined: 04 Jan 2008
Posts: 402
Location: Greenville , SC
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| Posted: Fri Feb 08, 2008 2:48 pm Post subject: Re: Elevator trim - 35 degree up and asymmetric geometry |
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Thanks for the re-post, Bill. ( http://forums.matronics.com/viewtopic.php?t=20576&highlight=twisted+tail ) This has been bugging the fool out of me ever since we finished that section and hooked up temporary 12 v. to it. Since I don't fly, I just accepted what Van's and others said ... "It's supposed to be that way", but it sure looked weird.
I can't wait to try your adjustment to see how that looks. It sure seems like looking at it in flight is the real test.
Later, - Lew
do not archive
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_________________
non-pilot
crazy about building
NOW OFICIALLY BUILDER #40549
Fly off completed ! |
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John Ackerman
Joined: 19 Jun 2006
Posts: 130
Location: Prescott, AZ
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| Posted: Sun Feb 10, 2008 3:14 pm Post subject: Elevator trim - 35 degree up and asymmetric geometry |
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Bill, my search finds nothing in the RV10 archives for "twisted tail"..The twisting moment doesn't depend on one elevator up, one down; just the difference in lift they're generating. Likewise with the drag resulting from differing angles of attack.
Is there reason to believe it's a big deal?
John Ackerman 40458 do not archive
On Feb 8, 2008, at 10:45 AM, Bill DeRouchey wrote:
[quote]It will matter when you are cruising with a load and need down trim and one elevator trim is slightly down and the other is slightly up. Suggest you search on my old post entitied "twisted tail".
Bill DeRouchey
N939SB
"Phillips, Jack" <Jack.Phillips(at)cardinalhealth.com (Jack.Phillips(at)cardinalhealth.com)> wrote:
[quote]--> RV10-List message posted by: "Phillips, Jack"
I'm glad to hear this. I had noticed the same thing and went through
the plans three times to make sure I hadn't screwed anything up. With
the elevators tied together it shouldn't matter if it's asymmetrical,
but it just looked a little odd.
Jack Phillips
#40610
Still waiting for the Wing Kit to arrive
--
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http://www.matronics.com/Navigator?RV10-List |
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ricksked(at)embarqmail.co
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