More Drywall Gussets

[Veeduber]

To All:

As promised, here on this Newsgroup about six weeks ago, I've posted a snapshot
of a rib gusset made from fiberglas drywall tape and polyurethane glue.

The photo is in the Files archive of the Fly5kfiles Group on Yahoo, in the
Practice Wing folder.

Other rib gusset experiments of possible interest: Resin-impregnated gasket
paper, coffee filters (!! -- you have to layer them but they fill the
grass-roots bill with regard to being inexpensive and commonly available) and
'parchment paper.'

Nothing very dramatic. Still experimenting, as time allows. Some interesting
results, possible suitable for low-speed, light-weight wing structures.

-R.S.Hoover

[Orval Fairbairn]

In article >,
"Morgans" > wrote:

> "Veeduber" > wrote in message
> ...
> > To All:
> >
> > As promised, here on this Newsgroup about six weeks ago, I've posted a
> snapshot
> > of a rib gusset made from fiberglas drywall tape and polyurethane glue.
> >
> > The photo is in the Files archive of the Fly5kfiles Group on Yahoo, in the
> > Practice Wing folder.
> >
>
> How about putting them somewhere else too? I don't do yahoo groups, for the
> fear of even more spam, which I have heard that Yahoo groups increase
> greatly.
>
> Also, have you done any tests to destruction, on these new gussets and ribs
> yet?
>
> > -R.S.Hoover
>
>

A big problem with polyurethane glue is deterioration due to water vapor
in the air. That is why polyurethane foam turns to dust after a few
years.

[Morgans]

"Veeduber" > wrote in message
...
> To All:
>
> As promised, here on this Newsgroup about six weeks ago, I've posted a
snapshot
> of a rib gusset made from fiberglas drywall tape and polyurethane glue.
>
> The photo is in the Files archive of the Fly5kfiles Group on Yahoo, in the
> Practice Wing folder.
>

How about putting them somewhere else too? I don't do yahoo groups, for the
fear of even more spam, which I have heard that Yahoo groups increase
greatly.

Also, have you done any tests to destruction, on these new gussets and ribs
yet?

> -R.S.Hoover

[Veeduber]

>A big problem with polyurethane glue is deterioration due to water vapor

---------------------------------------------------

Hahahahahahahahahaha ...wheeze.. gasp

Good one, Orval, thank you. Best laugh I've had all week :-)

-R.S.Hoover

PS - Although relatively new in the United States urethane-based adhesives have
been used in Europe for the last thirty years or so, in the construction of
boats, houses and airplanes (for us common folk) but also for the repair of
antique musical instruments, the wooden tube of an antique telescope at Riga
and by the people who do restorations for antique furniture, firearms, coaches
(!) and so forth.

If you haven't tried it, perhaps you should. Or simply go read the FPL reports
on the stuff. It needs quite a bit of pressure to ensure a 100% bond with wood
but otherwise, it's a pretty good glue.

(Urethane foam degrades due to exposure to ultraviolet rays, not water vapor.)

[Orval Fairbairn]

In article >,
(Veeduber) wrote:

> >A big problem with polyurethane glue is deterioration due to water vapor
>
> ---------------------------------------------------
>
> Hahahahahahahahahaha ...wheeze.. gasp
>
> Good one, Orval, thank you. Best laugh I've had all week :-)
>
> -R.S.Hoover
>
> PS - Although relatively new in the United States urethane-based adhesives
> have
> been used in Europe for the last thirty years or so, in the construction of
> boats, houses and airplanes (for us common folk) but also for the repair of
> antique musical instruments, the wooden tube of an antique telescope at Riga
> and by the people who do restorations for antique furniture, firearms,
> coaches
> (!) and so forth.
>
> If you haven't tried it, perhaps you should. Or simply go read the FPL
> reports
> on the stuff. It needs quite a bit of pressure to ensure a 100% bond with
> wood
> but otherwise, it's a pretty good glue.
>
> (Urethane foam degrades due to exposure to ultraviolet rays, not water
> vapor.)

Not true! Urethane foam will self-destruct in the dark! I had used some
for anti-chafing some years ago and it turned to dust.

Maybe we're thinking about different glues here. I certainly would like
to check out the FPL info on urethane glues.

How does it compare with T-88, good old Weldwood and Resorcinol?

Resorcinol and Weldwood make good joints, as long as you use enough
pressure, the joints make good contact and the curing temperature is
high enough.

[Nicholas Cafarelli]

I have also experimented with alternative materials and procedures for
rib gusset making. I commend Bob for his post and recommend that
people do their own experiments. The results will possibly surprise
you.

Consider these emails:

From: "Mark McAtee" > Add to Address Book
To:
Subject: Re: Paper Gussets
Date: Wed, 12 Nov 2003 16:34:50 +0000


The paper I used is 140 lb. Medium Weight Bienfang water color
paper.
You're right, I don't know where I got the 20lb thing. This was the
heaviest water color paper I could find at our local store. It really
works
well on light ribs. sucks up the West and does not need much clamping
pressure. I used sand filled beanbags. It also worked well with
normal
wood glue for testing purposes. Weldwood powder glue also worked
very
well. I don't like the gorilla glue because it does "foam" in the
joints.

>From: "Nicholas Cafarelli" >
>To:
>Subject: Paper Gussets
>Date: Tue, 04 Nov 2003 15:31:24 -0000
>
>Hello.
>
>You mention 20 lb paper in your post. I do not mean to second guess
>you, yet was the paper really this light? I suspect it may have been
>a much heavier weight paper. I could be dead wrong.
>
>Watercolor paper:
>
>http://www.dickblick.com/zz100/07/products.asp?param=0&ig_id=754
>
>at a much heavier weight, is another inexpensive option.
>
>I, too, experiment with gussets for much lighter aircraft - not
>Tailwinds.
>
>You might consider these other lighter, cheaper gusset forms:
>
>1. Drywall fiberglass tape laminated with epoxy.
>2. Drywall fiberglass tape laminated with Gorilla Glue.
>3. Other fiberglass laminated with epoxy.
>
>Regarding number two: pressure must be maintained while this type of
>gusset cures. The glue wants to expand. This incorporation of air
>makes the resulting gusset material very light and suprisingly strong
>and cheap.
>
>One thing I have yet to try is drywall fiberglass tape adhered with
>epoxy - NOT laminated. If tension can be maintained in the fibers I
>suspect that only the fiber area in contact with the rib sticks need
>be epoxied. This will NOT be as strong as complete lamination, yet
>it likely will be MORE than strong enough. In addition, as you and
>your students discovered firsthand, gusset flexibility can be an
>ADVANTAGE.
>
>Of course, you are the mechanic in charge, and workmanship and
>material choice can result in nonairworthy parts.
>

I have since experimented with other gussets:

1. cereal box/epoxy
2. cereal box/dollar store "sterling glue"
3. fiberglass drywall tape/epoxy
4. various other paper products/various adhesives

All of these are much stronger than you might think.

The variation I found most interesting involved type 3. I oriented
the strands at 45 degrees and only applied epoxy where the tape
touched the rib sticks and rib caps. Try it.

Based on hands-on work with these seemingly radical formulations, I
concur with Bob that for some lightweight applications they can serve
well.

Sometimes, good enough is good enough.

I should add that the testing I have done involved complete ribs. It
is my opinion that this most accurately predicts the true utility of
alternatives.

nc

[Veeduber]

Nicholas Cafarelli wrote:
>I should add that the testing I have done involved complete ribs. It
>is my opinion that this most accurately predicts the true utility of
>alternatives.

----------------------------------------------------------

To All:

Nick makes a good point here. I'm guilty of assuming everyone understood the
progression of the experimental process. Indeed, I had included a simple
rib-testing arrangement in the archive with the Practice Wing files.

I consider the individual gusset tests to be just the first step. Trying to
open up the box a bit, I have been using whatever gusset material and adhesive
came to hand to fabricate sample T-joints. When the sample appeared to justify
further study, a full rib was made & tested to destruction using the weight
distribution shown in the drawings. (Here again, keep in mind the drawing is
relative to the Practice Wing which uses a D-cell leading edge; the leading
edge is not included in the tests.)

Heavy paper of various types is showing the most promise as an alternative to
plywood. As a point of interest, all such gussets should be well sealed with
dilute varnish after the glue has cured. This not only protects the paper, it
serves to strengthen it.

-------------------------------------------------

Another assumption I've made is that anyone wishing to check or duplicate these
experiments should only do so AFTER making and breaking a number of ribs
fabricated in the traditional manner. I've used 1/8" luan plywood (ie,
'doorskins') gussets as the 'lo-buck' example and 1/16" aviation plywood
gussets as the 'regular' example.

Using 1/4" sticks, ribs fabricated in the traditional manner usually exceed the
worse-case strength requirements by 2X or more.

---------------------------------------------

Based on the mail I've received, most American, Canadian and Australian
homebuilders are relatively wealthy (compared to me) and see little merit in
such experiments, whereas homebuilders in India, China and Africa tend to be
more willing to at least consider alternative materials (mainly bamboo and
paper) and methods, even to making your own plywood (ie, laminated shavings,
suitable for rib gussets) and other labor-intensive techniques.

-R.S.Hoover

[Daniel]

"Morgans" wrote ...
> How about putting them somewhere else too? I don't do yahoo groups, for the
> fear of even more spam,...

Create a throwaway email account at http://www.mail.com Tell it that
your "real" email address is the same one that you're creating & that
you'll read your email through the mail.com web interface.

Use that new account to join the Yahoo group(s) of your choice & opt
for no email, that you'll read & post through the Yahoo web page
interface.

Any spam gets sent to your fake email address that you never check
anyway. Any replies to posts that you make on the Yahoo groups get
posted to the web page.

The email address I used for this post is from an outfit that cut off
email services a year ago (I read & post through Google).

Daniel

[Nicholas Cafarelli]

In my view paper based gussets are much easier to work with than
plywood. Cutting paper is a relatively clean and quick process
compared to preparing plywood gussets which require sanding. Some
might argue that the gluing is messier. On balance, I find I prefer
paper.

Given the low cost, easy availability, and low weight, I am surprised
they are not common on ultralight aircraft of wooden construction.

If you take a piece of paperboard, like from a cereal box, and pull on
it you will find it is quite strong in tension. I am convinced that
when paper is used as rib gussets, it is tensile strength which is
important. Plywood has an advantage in compression. Yet this
advantage is largely wasted in ribs.

The Heath Baby Bullet, which may have flown as fast as 200 mph in
dives used 1/32 inch thick gussets. I believe that thicker gussets
are often overkill.

When paperboard serves as gussets the tensile strength is enough for
many applications.

We know that columns fail in compression due to buckling. It seems
clear that gussets owe the larger part of their total strength to
tensile strength no matter what their material.

As always, materials and workmanship vary, so make your own thorough
tests.

It would seem advantageous to allow epoxy to soak into any paper
gusset.

nc