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1. 11:46 AM - Re: Rigging (teamgrumman@aol.com)
2. 02:34 PM - Re: Re: Rigging (Ian Matterface)
3. 10:26 PM - Re: Re: Rigging (teamgrumman@aol.com)
Message 1
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I'll post this on TeamGrumman-list for you. TeamGrumman-list is not
the same as TeamGrumman@aol.com
Many years ago, 23 years I think it was, I removed all of the trim tabs
from my Cheetah. You know, the trim tab on one aileron, the redundent
one on the other aileron, and the rudder trim tab. Then, I spent 2
weeks (I had a 40 hr/wk job at the time) playing with the rigging to
see if I could get the plane to fly straight and level without any trim
tabs. That was when I discovered it's the flaps that control roll, not
the ailerons. I also tried reflexing the ailerons up until the plane
got mushy, and then down until they acted like partially deployed
flaps. Then I tried doing the same with the flaps. I did find that
under certain loadings and winds (lots of wind on the desert) reflexing
the ailerons about 1 to 2 degrees (any more than that and there is no
gain. At 5 degrees, the plane is really mushy.) would let me get about
1 to 2 knots more airspeed. I fooled with this for about 5 years. As
for the flaps, I tried everything from flaps reflexed 7 to 8 degrees
(that is about the limit of adjustment) to about 5 degrees down. What
I found was, really, for all practical purposes, the factory settings
are about as close as you can get for a mixutre of loading and wind
conditions. Without a very accurate map of the lift/drag curve for the
wing and fuselage and horizontal (and an inclinometer to watch in the
plane), it's impossible to gauge the best settings for the ailerons and
flaps for each condition. At most, there is 1 or 2 knots hidden in the
adjustments. What I will say is, one of the tirm tabs on the aileron
is redundent. And, the rudder can be trimmed with tension on the cable
to achieve the desired rudder trim.
As for the holes, I'd put the backing plate back (that backs up the
tab) and flush rivet it in place.
-----Original Message-----
From: 923te@cox.net
Sent: Sun, 11 Mar 2007 11:11 PM
Subject: Rigging
Gary,
I thought about removing all the trim tabs as you suggested in your
post here.
The rudder trim tab is easy to remove but the ailerons will be harder
because they have so many rivets along 2 rows and will leave a lot of
holes which may effect drag and control???,,,
So my question is, for the aileron trim tabs, where is neutral. I
aligned them both with the chord of the flap. They look a little high in
flight....but maybe they're not???...
I have to have the right flap down 2 turns of the adjustment rod end
more than the left to fly straight and level.
Thanks,
Ned
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Message 2
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I asked the question "why two aileron trim tabs" of the AYA back in 94.
Dave Fletcher replied and you can see the full text if you are a AYA
member on their web site. Download the General Section of the
Maintenance Compendium page 15.
Part of Dave's reply was, "The preferred setting for the trim tabs is to
reduce lift on one aileron, rather than increase it on the other. How
you trim depends on which wing is heavy." and "Remember: bend the tab in
the direction you want that wing to go, and remember that bending one
tab down, which decreases that wing's lift and drag, is preferable to
bending the other tab up, which increases lift and drag for that wing."
So may be that last quote is the reason for two, if I read that
correctly, ideally one should always be neutral and the other down
depending on which wing is heavy.
Ian
----- Original Message -----
From: teamgrumman@aol.com
Sent: Monday, March 12, 2007 6:45 PM
Subject: TeamGrumman-List: Re: Rigging
I'll post this on TeamGrumman-list for you. TeamGrumman-list is not
the same as TeamGrumman@aol.com
Many years ago, 23 years I think it was, I removed all of the trim tabs
from my Cheetah. You know, the trim tab on one aileron, the redundent
one on the other aileron, and the rudder trim tab. Then, I spent 2
weeks (I had a 40 hr/wk job at the time) playing with the rigging to
see if I could get the plane to fly straight and level without any trim
tabs. That was when I discovered it's the flaps that control roll, not
the ailerons. I also tried reflexing the ailerons up until the plane
got mushy, and then down until they acted like partially deployed
flaps. Then I tried doing the same with the flaps. I did find that
under certain loadings and winds (lots of wind on the desert) reflexing
the ailerons about 1 to 2 degrees (any more than that and there is no
gain. At 5 degrees, the plane is really mushy.) would let me get about
1 to 2 knots more airspeed. I fooled with this for about 5 years. As
for the flaps, I tried everything from flaps reflexed 7 to 8 degrees
(that is about the limit of adjustment) to about 5 degrees down. What
I found was, really, for all practical purposes, the factory settings
are about as close as you can get for a mixutre of loading and wind
conditions. Without a very accurate map of the lift/drag curve for the
wing and fuselage and horizontal (and an inclinometer to watch in the
plane), it's impossible to gauge the best settings for the ailerons and
flaps for each condition. At most, there is 1 or 2 knots hidden in the
adjustments. What I will say is, one of the tirm tabs on the aileron
is redundent. And, the rudder can be trimmed with tension on the cable
to achieve the desired rudder trim.
As for the holes, I'd put the backing plate back (that backs up the
tab) and flush rivet it in place.
-----Original Message-----
From: 923te@cox.net
Sent: Sun, 11 Mar 2007 11:11 PM
Subject: Rigging
Gary,
I thought about removing all the trim tabs as you suggested in your
post here.
The rudder trim tab is easy to remove but the ailerons will be harder
because they have so many rivets along 2 rows and will leave a lot of
holes which may effect drag and control???,,,
So my question is, for the aileron trim tabs, where is neutral. I
aligned them both with the chord of the flap. They look a little high in
flight....but maybe they're not???...
I have to have the right flap down 2 turns of the adjustment rod end
more than the left to fly straight and level.
Thanks,
Ned
________________________________________________________________________
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Message 3
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I see a lot of plane that require one tab significantly up with the
other significantly down. This tells me that instead of making the
plane fly right with proper rigging, people are compensating with trim
tabs.
ALSO, how do you know when tab is neutral? I think that was in the
original post.
If a tab is a tweaked up, it affects that wing. To correct that wing,
the other is tweaked up also.
Removing one tab makes the correction to one aileron.
Now, it there less drag with one aileron up slightly to correct a light
wing? or is there less drag with two tabs making the ailerons fight
each other?
For me, I have one trim tab that is nearly neutral. And, now I need to
see if it's up or down . . . . . . . . . . . . .
-----Original Message-----
From: i.r.m@btinternet.com
Sent: Mon, 12 Mar 2007 2:34 PM
Subject: Re: TeamGrumman-List: Re: Rigging
I asked the question "why two aileron trim tabs" of the AYA back
in 94. Dave Fletcher replied and you can see the full text if you are a
AYA member on their web site. Download the General Section of the
Maintenance Compendium page 15.
Part of Dave's reply was, "The preferred setting for the trim tabs is
to reduce lift on one aileron, rather than increase it on the other.
How you trim depends on which wing is heavy." and "Remember: bend the
tab in the direction you want that wing to go, and remember that
bending one tab down, which decreases that wing's lift and drag, is
preferable to bending the other tab up, which increases lift and drag
for that wing." So may be that last quote is the reason for two, if I
read that correctly, ideallyone should always be neutral and the other
down depending on which wing is heavy.
Ian
----- Original Message ----- From: teamgrumman@aol.com
To: 923te@cox.net ; teamgrumman-list@matronics.com
Sent: Monday, March 12, 2007 6:45 PM
Subject: TeamGrumman-List: Re: Rigging
I'll post this on TeamGrumman-list for you. TeamGrumman-list is not
the same as TeamGrumman@aol.com
Many years ago, 23 years I think it was, I removed all of the trim tabs
from my Cheetah. You know, the trim tab on one aileron, the redundent
one on the other aileron, and the rudder trim tab. Then, I spent 2
weeks (I had a 40 hr/wk job at the time) playing with the rigging to
see if I could get the plane to fly straight and level without any trim
tabs. That was when I discovered it's the flaps that control roll, not
the ailerons. I also tried reflexing the ailerons up until the plane
got mushy, and then down until they acted like partially deployed
flaps. Then I tried doing the same with the flaps. I did find that
under certain loadings and winds (lots of wind on the desert) reflexing
the ailerons about 1 to 2 degrees (any more than that and there is no
gain. At 5 degrees, the plane is really mushy.) would let me get about
1 to 2 knots more airspeed. I fooled with this for about 5 years. As
for the flaps, I tried everything from flaps reflexed 7 to 8 degrees
(that is about the limit of adjustment) to about 5 degrees down. What
I found was, really, for all practical purposes, the factory settings
are about as close as you can get for a mixutre of loading and wind
conditions. Without a very accurate map of the lift/drag curve for the
wing and fuselage and horizontal (and an inclinometer to watch in the
plane), it's impossible to gauge the best settings for the ailerons and
flaps for each condition. At most, there is 1 or 2 knots hidden in the
adjustments. What I will say is, one of the tirm tabs on the aileron
is redundent. And, the rudder can be trimmed with tension on the cable
to achieve the desired rudder trim.
As for the holes, I'd put the backing plate back (that backs up the
tab) and flush rivet it in place.
-----Original Message-----
From: 923te@cox.net
Sent: Sun, 11 Mar 2007 11:11 PM
Subject: Rigging
Gary,
I thought about removing all the trim tabs as you suggested in your
post here.
The rudder trim tab is easy to remove but the ailerons will be harder
because they have so many rivets along 2 rows and will leave a lot of
holes which may effect drag and control???,,,
So my question is, for the aileron trim tabs, where is neutral. I
aligned them both with the chord of the flap. They look a little high in
flight....but maybe they're not???...
I have to have the right flap down 2 turns of the adjustment rod end
more than the left to fly straight and level.
Thanks,
Ned
________________________________________________________________________
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