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Matt Dralle
Site Admin
Joined: 08 Nov 2005
Posts: 25858
Location: Livermore CA USA
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 Posted: Sat Aug 23, 2008 3:55 pm Post subject: Elevator Skin Trailing Edge Bowing... |
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Dear Listers,
Backing into the garage today I noticed the elevator skin bowing at
the trailing edge in the review mirror because of the way the light
was hitting it. Basically what the deal is I think is that I bent
the trailing edge of the elevators more than necessary. So, when I
pulled the leading edge apart to fit it over the spar, I now have a
concave bowing effect between some of the bays. Van's goes to great
lengths in the manual to make sure that bend the elevator trailing
edges *enough*, but doesn't make mention of what is "too much". The
radius of the trailing edge is still within spec and there is no
cracking or stress marks. Its just bent too much and looks like of
stupid. Somehow, I did the rudder perfectly, but both elevators
suffer from the effect. I've included some pictures below.
What the common thought on this issue? Are the safety/flutter issues
with over-bending as I have done? What to do...?
Thanks!
Matt Dralle
RV-8 #82880
RV-8 Fuse/Wing QB Kit Delivery Next Week! (Ordered May 20 2008)
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ceengland(at)bellsouth.ne
Guest
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| Posted: Sat Aug 23, 2008 6:14 pm Post subject: Elevator Skin Trailing Edge Bowing... |
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Matt Dralle wrote:
| Quote: |
Dear Listers,
Backing into the garage today I noticed the elevator skin bowing at
the trailing edge in the review mirror because of the way the light
was hitting it. Basically what the deal is I think is that I bent the
trailing edge of the elevators more than necessary. So, when I pulled
the leading edge apart to fit it over the spar, I now have a concave
bowing effect between some of the bays. Van's goes to great lengths
in the manual to make sure that bend the elevator trailing edges
*enough*, but doesn't make mention of what is "too much". The radius
of the trailing edge is still within spec and there is no cracking or
stress marks. Its just bent too much and looks like of stupid.
Somehow, I did the rudder perfectly, but both elevators suffer from
the effect. I've included some pictures below.
What the common thought on this issue? Are the safety/flutter issues
with over-bending as I have done? What to do...?
Thanks!
Matt Dralle
RV-8 #82880
RV-8 Fuse/Wing QB Kit Delivery Next Week! (Ordered May 20 2008)
|
I'll bet that there are many flying that look worse.
Do you have RTV in the bend? If yes, you might be stuck with what you've
got. If not:
If it really bothers you, try this (try on a test piece made from some
scrap first). Hold a piece of wood against the trailing edge so that it
spans most of one bay. Use a rubber mallet to drive the wood toward the
trailing edge. Light blows at first, checking for movement. If you use
rigid wood, take care to hit the center of the block so that the force
is spread evenly. Light plywood (1/4" or 3/8") minimizes the risk of the
wood's edge digging in & causing a dent. If you put the assembly on some
foam rubber, it will reduce the risk of over-correcting (or bending
something else) since it can move a bit when struck. Work along the
edge with multiple blows & check often.
I used this technique on an aileron when I over-bent trying to fix a
heavy wing.
Charlie
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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Matt Dralle
Site Admin
Joined: 08 Nov 2005
Posts: 25858
Location: Livermore CA USA
|
| Posted: Sun Aug 24, 2008 8:56 am Post subject: Elevator Skin Trailing Edge Bowing... |
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At 07:09 PM 8/23/2008 Saturday, you wrote:
| Quote: |
Matt Dralle wrote:
>
>Dear Listers,
>
>Backing into the garage today I noticed the elevator skin bowing at the trailing edge in the review mirror because of the way the light was hitting it. Basically what the deal is I think is that I bent the trailing edge of the elevators more than necessary. So, when I pulled the leading edge apart to fit it over the spar, I now have a concave bowing effect between some of the bays. Van's goes to great lengths in the manual to make sure that bend the elevator trailing edges *enough*, but doesn't make mention of what is "too much". The radius of the trailing edge is still within spec and there is no cracking or stress marks. Its just bent too much and looks like of stupid.
>Somehow, I did the rudder perfectly, but both elevators suffer from the effect. I've included some pictures below.
>
>What the common thought on this issue? Are the safety/flutter issues with over-bending as I have done? What to do...?
>
>Thanks!
>
>Matt Dralle
>RV-8 #82880
>RV-8 Fuse/Wing QB Kit Delivery Next Week! (Ordered May 20 2008)
I'll bet that there are many flying that look worse.
Do you have RTV in the bend? If yes, you might be stuck with what you've got. If not:
If it really bothers you, try this (try on a test piece made from some scrap first). Hold a piece of wood against the trailing edge so that it spans most of one bay. Use a rubber mallet to drive the wood toward the trailing edge. Light blows at first, checking for movement. If you use rigid wood, take care to hit the center of the block so that the force is spread evenly. Light plywood (1/4" or 3/8") minimizes the risk of the wood's edge digging in & causing a dent. If you put the assembly on some foam rubber, it will reduce the risk of over-correcting (or bending something else) since it can move a bit when struck. Work along the edge with multiple blows & check often.
I used this technique on an aileron when I over-bent trying to fix a heavy wing.
|
I did use a little RTV in the trailing edges. I can definitely see how that technique could "unbend" it a bit, but it sounds really scary wacking away on the trailing edge like that. Were there any adverse results of the process?
Matt Dralle
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
|
_________________
Matt Dralle
Matronics Email List Administrator |
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ceengland(at)bellsouth.ne
Guest
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| Posted: Sun Aug 24, 2008 10:53 am Post subject: Elevator Skin Trailing Edge Bowing... |
|
|
Matt Dralle wrote:
| Quote: |
At 07:09 PM 8/23/2008 Saturday, you wrote:
>
>
> Matt Dralle wrote:
>
>>
>> Dear Listers,
>>
>> Backing into the garage today I noticed the elevator skin bowing at the trailing edge in the review mirror because of the way the light was hitting it. Basically what the deal is I think is that I bent the trailing edge of the elevators more than necessary. So, when I pulled the leading edge apart to fit it over the spar, I now have a concave bowing effect between some of the bays. Van's goes to great lengths in the manual to make sure that bend the elevator trailing edges *enough*, but doesn't make mention of what is "too much". The radius of the trailing edge is still within spec and there is no cracking or stress marks. Its just bent too much and looks like of stupid.
>> Somehow, I did the rudder perfectly, but both elevators suffer from the effect. I've included some pictures below.
>>
>> What the common thought on this issue? Are the safety/flutter issues with over-bending as I have done? What to do...?
>>
>> Thanks!
>>
>> Matt Dralle
>> RV-8 #82880
>> RV-8 Fuse/Wing QB Kit Delivery Next Week! (Ordered May 20 2008)
>>
> I'll bet that there are many flying that look worse.
>
> Do you have RTV in the bend? If yes, you might be stuck with what you've got. If not:
>
> If it really bothers you, try this (try on a test piece made from some scrap first). Hold a piece of wood against the trailing edge so that it spans most of one bay. Use a rubber mallet to drive the wood toward the trailing edge. Light blows at first, checking for movement. If you use rigid wood, take care to hit the center of the block so that the force is spread evenly. Light plywood (1/4" or 3/8") minimizes the risk of the wood's edge digging in & causing a dent. If you put the assembly on some foam rubber, it will reduce the risk of over-correcting (or bending something else) since it can move a bit when struck. Work along the edge with multiple blows & check often.
>
> I used this technique on an aileron when I over-bent trying to fix a heavy wing.
>
I did use a little RTV in the trailing edges. I can definitely see how that technique could "unbend" it a bit, but it sounds really scary wacking away on the trailing edge like that. Were there any adverse results of the process?
Matt Dralle
No adverse affects if it's done right.  I did it in '94 on a plane I
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bought already flying. I sold it in 2001 & haven't heard of any issues
since then. FWIW, I don't think that I dreamed this up; it probably came
from someone more experienced than me at the time.
If the RTV is down in the fold where you need to open it up, it'll be a
real problem to open the fold without causing more problems. If it just
bridges between the stiffeners (away from the fold), you can probably
get away with it.
You're right, it is scary & you can do more harm than good. Note that I
said 'if it really bothers you'.
Option 1, leave it alone; unless you're building an award contender,
only you will talk about it. ("A gentleman never points out [cosmetic]
flaws in another gentleman's creation.") As I said, there are many
flying safely that are much worse.
Option 2, (if you just can't stand it), try it; it will either work or
not and since you'd be building another anyway you have nothing to lose.
Option 3, disassemble to open it up (pretty much the same as building a
new one).
Option 4, ask Van's (they will say pick option 1 ).
Charlie
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
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