Extra bracing

[Lou]

I have just started to assemble my wings on my all wood aircraft. There
is a box spar in the front and a 3/4" thick spar in the back. Although
this will no dought hold together, it only calls for 1 diagnal brace on
each wing. I glued temperary
diagnal braces on the inside to hold while I start to cover. This has
added an extreme amount of strength. Now that I've led to the big
question. Since this will add only 1lbs to the airframe, does anyone
think it would be a good idea to keep the extra bracing? Or make the
frame too stiff?
Lou

[Rich S.]

"Lou" > wrote in message
oups.com...
>I have just started to assemble my wings on my all wood aircraft. There
> is a box spar in the front and a 3/4" thick spar in the back. Although
> this will no dought hold together, it only calls for 1 diagnal brace on
> each wing. I glued temperary
> diagnal braces on the inside to hold while I start to cover. This has
> added an extreme amount of strength. Now that I've led to the big
> question. Since this will add only 1lbs to the airframe, does anyone
> think it would be a good idea to keep the extra bracing? Or make the
> frame too stiff?
> Lou

Lou...........

Are you building from commercial plans? May I ask which model of airframe
this is?

Be very careful in deciding on your own to make any changes whatsoever to
the construction. Consult the designer if you feel something is in error. If
he or she is not available, consult with an aircraft design engineer.

Believe me, these "only one pound" items add up rapidly and may induce
stresses that the design is not able to handle. Remember the builder's code
and repeat after me:

Follow the plans, add only lightness.
Follow the plans, add only lightness.
Follow the plans, add only lightness.

Rich S.

[alexy]

"Lou" > wrote:

>I have just started to assemble my wings on my all wood aircraft. There
>is a box spar in the front and a 3/4" thick spar in the back. Although
>this will no dought hold together, it only calls for 1 diagnal brace on
>each wing. I glued temperary
>diagnal braces on the inside to hold while I start to cover. This has
>added an extreme amount of strength. Now that I've led to the big
>question. Since this will add only 1lbs to the airframe, does anyone
>think it would be a good idea to keep the extra bracing? Or make the
>frame too stiff?
> Lou

While the added stiffness may initially sound appealing, what you are
doing is taking stresses that the designer planned to be absorbed in
the flexing of the wing and transferring them all to the attachment
between the wing and the fuse. Doesn't sound like a good idea.


--
Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.

[Ed Sullivan]

On 15 Apr 2005 12:05:14 -0700, "Lou" > wrote:

>I have just started to assemble my wings on my all wood aircraft. There
>is a box spar in the front and a 3/4" thick spar in the back. Although
>this will no dought hold together, it only calls for 1 diagnal brace on
>each wing. I glued temperary
>diagnal braces on the inside to hold while I start to cover. This has
>added an extreme amount of strength. Now that I've led to the big
>question. Since this will add only 1lbs to the airframe, does anyone
>think it would be a good idea to keep the extra bracing? Or make the
>frame too stiff?
> Lou
>
I don't know what you are building and it would help in anwering your
question. My Jungster II has one diagonal wooden brace in the middle
of 3 fabric covered bays, however the wing is covered with plywood
skins top and bottom from the 3rd rib to the tip which forms a very
rigid box. No other diagonal bracing is necessary.

Ed Sullivan

[Mark Hickey]

"Lou" > wrote:

>I have just started to assemble my wings on my all wood aircraft. There
>is a box spar in the front and a 3/4" thick spar in the back. Although
>this will no dought hold together, it only calls for 1 diagnal brace on
>each wing. I glued temperary
>diagnal braces on the inside to hold while I start to cover. This has
>added an extreme amount of strength. Now that I've led to the big
>question. Since this will add only 1lbs to the airframe, does anyone
>think it would be a good idea to keep the extra bracing? Or make the
>frame too stiff?

As others have pointed out, "be careful".

Think of this extreme example...

Say you have a 10' piece of 1" OD PVC pipe, and one end is anchored
firmly, and a weight of plus and minus 10 pounds is applied to the
other end a thousand times a day. Not hard to imagine what happens -
lots o' flexing.

Now take a 9.8' piece of steel 1" ID water pipe and slide it over the
PVC pipe and apply the same loading. In short order you'll have a
broken piece of PVC pipe at the anchored end.

Mark "and you don't wanna break your PVC in flight" Hickey

[Lou]

Well I have to say, these are points that I had considered, but it's
good to have
other's opinions to verify. I'll remove the extra bracing once I start
to cover.
Lou

[Mark Smith]

Mark Hickey wrote:
>
> "Lou" > wrote:
>
> >I have just started to assemble my wings on my all wood aircraft. There
> >is a box spar in the front and a 3/4" thick spar in the back. Although
> >this will no dought hold together, it only calls for 1 diagnal brace on
> >each wing. I glued temperary
> >diagnal braces on the inside to hold while I start to cover. This has
> >added an extreme amount of strength. Now that I've led to the big
> >question. Since this will add only 1lbs to the airframe, does anyone
> >think it would be a good idea to keep the extra bracing? Or make the
> >frame too stiff?
>
> As others have pointed out, "be careful".
>
> Think of this extreme example...
>
> Say you have a 10' piece of 1" OD PVC pipe, and one end is anchored
> firmly, and a weight of plus and minus 10 pounds is applied to the
> other end a thousand times a day. Not hard to imagine what happens -
> lots o' flexing.
>
> Now take a 9.8' piece of steel 1" ID water pipe and slide it over the
> PVC pipe and apply the same loading. In short order you'll have a
> broken piece of PVC pipe at the anchored end.
>
> Mark "and you don't wanna break your PVC in flight" Hickey


exactly what stresses increase due to adding the outer sleeve of steel,
assuming your 'steel' adds no weight or inertia to the problem,,,,,,,


--
Mark Smith
Tri-State Kite Sales
1121 N Locust St
Mt Vernon, IN 47620
1-812-838-6351
http://www.trikite.com

[UltraJohn]

Mark Smith wrote:

> exactly what stresses increase due to adding the outer sleeve of steel,
> assuming your 'steel' adds no weight or inertia to the problem,,,,,,,
>
>
For starters all your flexing is now done on the end instead of gradually
over the length of the pipe. IE willow verses oak!
John

[Mark Smith]

UltraJohn wrote:
>
> Mark Smith wrote:
>
> > exactly what stresses increase due to adding the outer sleeve of steel,
> > assuming your 'steel' adds no weight or inertia to the problem,,,,,,,
> >
> >
> For starters all your flexing is now done on the end instead of gradually
> over the length of the pipe. IE willow verses oak!
> John


does the reduced flexing with the sleeve increase or reduce the stresses
at the wing root ?
--
Mark Smith
Tri-State Kite Sales
1121 N Locust St
Mt Vernon, IN 47620
1-812-838-6351
http://www.trikite.com

[UltraJohn]

Mark Smith wrote:

> UltraJohn wrote:
>>
>> Mark Smith wrote:
>>
>> > exactly what stresses increase due to adding the outer sleeve of steel,
>> > assuming your 'steel' adds no weight or inertia to the problem,,,,,,,
>> >
>> >
>> For starters all your flexing is now done on the end instead of gradually
>> over the length of the pipe. IE willow verses oak!
>> John
>
>
> does the reduced flexing with the sleeve increase or reduce the stresses
> at the wing root ?

It definitely increases the stress.
Without the pipe the length of pvc absorbs energy along it's length with the
pipe over it all the stress is reflected at the end.
John

Look at the wing of an airliner the next time you fly and you'd be amazed at
how much it flexes. If they stiffened it to the point it didn't flex you'd
end up on the ground do a pretty quick vertical decent. Not Good!