Today's Message Index:
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1. 04:19 AM - Heavy wing help (Neilekins@aol.com)
2. 03:00 PM - Re: Heavy wing (Matthew Brandes)
3. 05:36 PM - Re: Re: Heavy wing (rv-9a-online)
Message 1
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--> RV9-List message posted by: Neilekins@aol.com
Im hoping to get some advice on a fix for a heavy wing....NC
Message 2
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--> RV9-List message posted by: "Matthew Brandes" <matthew@n523rv.com>
Dug this out of the Yahoo RV-9A group.. (Search tool sucks.. just search
for 'heavy' and scroll down.)
From: "bryanwoodrv9a" <brywd@sbcglobal.net>
Subject: Fixing a heavy wing on a 9A
Hello fellow RVators,
Thought I'd post results on correcting for a heavy wing on a 9A. On
other RV's the trick is to sqeeze the trailing edge of the aileron
until the problem gets better, but with the trailing edges on our
planes the way they are they cannot really be bent.
I'm going to go through all of the things that I tried so maybe some
of you won't go through all of the same bad ideas. As for the wing
being heavy... It took several pounds of pressure on the stick to
hold the left wing level. This was after carefully measuring the
wing incidence. The leading edges were straight to the chaulk line
with four plumb bobs used to mark it. The same rivet on the outboard
wing rib to the same on the tail on both sides gave less than 1/16"
difference. The incidence was set with a smart level and both wings
are within 1/10 degree of each other. The bellcranks were set to
neutral with the jig that came with the kit, and the ailerons set in
line. The flaps, ailerons, and tips were all in line with each other
and the plane had a heavy left wing. At this point here is what I
tried, in order of failure, until finally a reasonable solution seems
possable.
1. I tried lowering the flap on the heavy wing to pick it up a bit.
I started by turning the rod end bearing in 1/2 turn intervals and
flying it each time. To be safe the rod end bearings at each end of
the left actuater were turned to prevent either from not having
enough threads engaged. When the number hit 10 1/2 turns the wing
was balanced. This obviously couldn't be good. The flap was
noticably lower than the other and with the extension speed at 90mph
on the 9A it just couldn't stay. I continued to the 10 1/2 turn only
to try and quantify the extent of the wing heavy problem. What does
it mean? I have no idea! I put the flap back.
2. From a piece of scrap aluminum long enough to span 5 rivets on
the trailing edge of the heavy wings aileron I made a trim tab much
like the ones you see on production planes. The problem with this
was the strength of the aileron. It seemed like the skin of the
aileron wanted to buckle when bending the tab to make adjustments.
This worked, looked ugly, and caused aileron deflection for level
flight. It seemed like it would cause a lot of drag to fly around
like this. Off came the trim tab.
3. Bought model airplane trailing edge material (balsa) and put it
under the opposite aileron. This effectively did what the other trim
tab did, but wasn't easily seen. Took this off too.
4. Tried the wedge shaped balsa under the wing tip trailing edge
thinking that enough up pressure could be generated to lift the heavy
wing. This did nothing. I still don't know why, because it seems so
obvious that it would work. I also thought as a kid I could jump off
of the fence with an umbrella and it would work like a parachute. I
even pre tested it on by jumping off of the porch and could tell by
the pull on the umbrella that it was going to work. Anyway, off the
fence I went and my knees just about crushed my cheeks on impact.
5. Tried adjusting the ailerons to compensate for the heavy wing.
Learned that the ailerons trail the airplane, but now the stick is
leaned over. This is no good. Undid this one also. Seriously
started to question my understanding of how airplanes fly. Okay, now
wondering how they do.
6. Idea! The aileron has almost twice the travel up as it does down
so this could be used. Maybe it will have less drag to have one
aileron deflected to hold up the heavy wing, than use a trim tab and
have both ailerons deflected. Since the bellcrank is basically a cam
with the aileron moving up having approx. twice the leverage as the
one moving down,(my own theory, developed in frustration) the
opposite aileron could be rigged down from neutral. As the wind hits
it will go up until it trails because it has all of the leverage.
This will displace only the aileron on the heavy wing down in flight
effectively lifting the wing. This worked great! I flew all of my
test time off and the plane has flown hands off ever since.
I knew however that this still wasn't right so I decided to call
Van's one more time for the answer. Depending on who I talked while
sorting out this problem the basic idea was to just put a trim tab
and call it a day. Finally I was told to slot the mounting brackets
on the ailerons and raise and lower them to figure out what is
wrong. Actually, they said I should see a slight difference in the
way the ailerons sit and to correct by raising or lowering to correct
for this.
7. The outboard of the opposite aileron from the heavy wing was
slightly higher than the heavy side. The steel bracket was removed
from the aileron and slotted so the aileron could be lowered in small
increments. Today I flew it with neutral ailerons again, rigged
correctly, etc. and the wing is almost completly balanced with the
ailerons in line in level cruise. Just minor tweaking and everything
should be good.
Now the electric aileron trim can be hooked back up and it will
probably be all that is needed from here. I took the springs off
essentially disabling it while trying to figure this out. This is
the last squawk on the plane and it is off to the paint shop in about
four more weeks.
Regards,
Bryan
Matthew Brandes,
Van's RV-9A (Finish Kit)
#90569
<http://www.n523rv.com/> http://www.n523rv.com
EAA Chapter 1329 President
EAA Chapter 868 Web Editor
Message 3
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| Subject: | Re: RE: Heavy wing |
--> RV9-List message posted by: rv-9a-online <rv-9a-online@telus.net>
I have just noticed that the right wing tip of the fiberglass fairing on
my -9A is 1-1/8" low (i.e. twisted), but the left wing tip fits
perfectly. This twist basically is due to a hook (increased camber) and
twist in the wing tip airfoil.
Not good.
I've contacted Van's and I hope to get the wing tip replaced under
warranty. Any misalignment of the wing tip will have a large affect on
roll trim.
Vern Little
90577
Matthew Brandes wrote:
>--> RV9-List message posted by: "Matthew Brandes" <matthew@n523rv.com>
>
>Dug this out of the Yahoo RV-9A group.. (Search tool sucks.. just search
>for 'heavy' and scroll down.)
>
>
>From: "bryanwoodrv9a" <brywd@sbcglobal.net>
>Date: Sat Mar 5, 2005 8:35 pm
>Subject: Fixing a heavy wing on a 9A
>
>Hello fellow RVators,
>
>Thought I'd post results on correcting for a heavy wing on a 9A. On
>other RV's the trick is to sqeeze the trailing edge of the aileron
>until the problem gets better, but with the trailing edges on our
>planes the way they are they cannot really be bent.
>
>I'm going to go through all of the things that I tried so maybe some
>of you won't go through all of the same bad ideas. As for the wing
>being heavy... It took several pounds of pressure on the stick to
>hold the left wing level. This was after carefully measuring the
>wing incidence. The leading edges were straight to the chaulk line
>with four plumb bobs used to mark it. The same rivet on the outboard
>wing rib to the same on the tail on both sides gave less than 1/16"
>difference. The incidence was set with a smart level and both wings
>are within 1/10 degree of each other. The bellcranks were set to
>neutral with the jig that came with the kit, and the ailerons set in
>line. The flaps, ailerons, and tips were all in line with each other
>and the plane had a heavy left wing. At this point here is what I
>tried, in order of failure, until finally a reasonable solution seems
>possable.
>
>1. I tried lowering the flap on the heavy wing to pick it up a bit.
>I started by turning the rod end bearing in 1/2 turn intervals and
>flying it each time. To be safe the rod end bearings at each end of
>the left actuater were turned to prevent either from not having
>enough threads engaged. When the number hit 10 1/2 turns the wing
>was balanced. This obviously couldn't be good. The flap was
>noticably lower than the other and with the extension speed at 90mph
>on the 9A it just couldn't stay. I continued to the 10 1/2 turn only
>to try and quantify the extent of the wing heavy problem. What does
>it mean? I have no idea! I put the flap back.
>
>2. From a piece of scrap aluminum long enough to span 5 rivets on
>the trailing edge of the heavy wings aileron I made a trim tab much
>like the ones you see on production planes. The problem with this
>was the strength of the aileron. It seemed like the skin of the
>aileron wanted to buckle when bending the tab to make adjustments.
>This worked, looked ugly, and caused aileron deflection for level
>flight. It seemed like it would cause a lot of drag to fly around
>like this. Off came the trim tab.
>
>3. Bought model airplane trailing edge material (balsa) and put it
>under the opposite aileron. This effectively did what the other trim
>tab did, but wasn't easily seen. Took this off too.
>
>4. Tried the wedge shaped balsa under the wing tip trailing edge
>thinking that enough up pressure could be generated to lift the heavy
>wing. This did nothing. I still don't know why, because it seems so
>obvious that it would work. I also thought as a kid I could jump off
>of the fence with an umbrella and it would work like a parachute. I
>even pre tested it on by jumping off of the porch and could tell by
>the pull on the umbrella that it was going to work. Anyway, off the
>fence I went and my knees just about crushed my cheeks on impact.
>
>5. Tried adjusting the ailerons to compensate for the heavy wing.
>Learned that the ailerons trail the airplane, but now the stick is
>leaned over. This is no good. Undid this one also. Seriously
>started to question my understanding of how airplanes fly. Okay, now
>wondering how they do.
>
>
>6. Idea! The aileron has almost twice the travel up as it does down
>so this could be used. Maybe it will have less drag to have one
>aileron deflected to hold up the heavy wing, than use a trim tab and
>have both ailerons deflected. Since the bellcrank is basically a cam
>with the aileron moving up having approx. twice the leverage as the
>one moving down,(my own theory, developed in frustration) the
>opposite aileron could be rigged down from neutral. As the wind hits
>it will go up until it trails because it has all of the leverage.
>This will displace only the aileron on the heavy wing down in flight
>effectively lifting the wing. This worked great! I flew all of my
>test time off and the plane has flown hands off ever since.
>
>I knew however that this still wasn't right so I decided to call
>Van's one more time for the answer. Depending on who I talked while
>sorting out this problem the basic idea was to just put a trim tab
>and call it a day. Finally I was told to slot the mounting brackets
>on the ailerons and raise and lower them to figure out what is
>wrong. Actually, they said I should see a slight difference in the
>way the ailerons sit and to correct by raising or lowering to correct
>for this.
>
>7. The outboard of the opposite aileron from the heavy wing was
>slightly higher than the heavy side. The steel bracket was removed
>from the aileron and slotted so the aileron could be lowered in small
>increments. Today I flew it with neutral ailerons again, rigged
>correctly, etc. and the wing is almost completly balanced with the
>ailerons in line in level cruise. Just minor tweaking and everything
>should be good.
>
>Now the electric aileron trim can be hooked back up and it will
>probably be all that is needed from here. I took the springs off
>essentially disabling it while trying to figure this out. This is
>the last squawk on the plane and it is off to the paint shop in about
>four more weeks.
>
>Regards,
>Bryan
>
>
>Matthew Brandes,
>Van's RV-9A (Finish Kit)
>#90569
> <http://www.n523rv.com/> http://www.n523rv.com
>
>EAA Chapter 1329 President
>EAA Chapter 868 Web Editor
>
>
>
>
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