Rib stitching vs glueing

[[email protected]]

I was reading some information on Fisher Celebrity builders websites
and saw that one builder did not like the idea of glueing the fabric to
the ribs as per the plans. The ribs on the Celebrity are very thin and
he didn't think there was enough glue area for a satisfactory bond, so
he rib stitched.

I also recall reading somewhere that the glue area doesn't really
affect the strength of the bond between the fabric and wood rib ( which
I can't believe )

I know the wing loading of the Celebrity is low compared to some of the
more high performance bipes, but if the glue area is such a concern,
wouldn't it be OK to just increase the rib capstrip width slightly to
give more glueing area? Might only increase the whole airplane weight
half a pound.

Thoughts? Thanks

Neal

[Stealth Pilot]

On 12 Oct 2005 14:33:47 -0700, wrote:

>I was reading some information on Fisher Celebrity builders websites
>and saw that one builder did not like the idea of glueing the fabric to
>the ribs as per the plans. The ribs on the Celebrity are very thin and
>he didn't think there was enough glue area for a satisfactory bond, so
>he rib stitched.
>
>I also recall reading somewhere that the glue area doesn't really
>affect the strength of the bond between the fabric and wood rib ( which
>I can't believe )
>
>I know the wing loading of the Celebrity is low compared to some of the
>more high performance bipes, but if the glue area is such a concern,
>wouldn't it be OK to just increase the rib capstrip width slightly to
>give more glueing area? Might only increase the whole airplane weight
>half a pound.
>
>Thoughts? Thanks
>
>Neal

of course!

btw dont be beguiled by the semantics.
the glue strength doesnt change with the glue area since it is a force
per unit area measurement.
the glue area directly changes the amount of total force that the rib
fabric join can stand.
a pound per square inch strength applied to a square inch can hold a
pound
a pound per square inch strength applied over a square foot can hold
one hundred and fourty four pounds.

Stealth Pilot
Australia

[[email protected]]

On 12 Oct 2005 14:33:47 -0700, wrote:

>I was reading some information on Fisher Celebrity builders websites
>and saw that one builder did not like the idea of glueing the fabric to
>the ribs as per the plans. The ribs on the Celebrity are very thin and
>he didn't think there was enough glue area for a satisfactory bond, so
>he rib stitched.

The Celebrity is a biplane with a top speed of 95 mph, right? Has it
been a problem? Have any of the Celebrity's that had the fabric glued
had the fabric come unstuck? Ever?

If not, why should it be considered an issue?

On the other hand, if the guy just cannot live with attaching the
fabric with glue, even if nothing bad has ever happened, he can
certainly rib stitch. It won't hurt anything but his wallet, a bit,
and add to the length of time building.

Corky Scott

[Smitty Two]

In article >,
Stealth Pilot > wrote:


> btw dont be beguiled by the semantics.
> the glue strength doesnt change with the glue area since it is a force
> per unit area measurement.
> the glue area directly changes the amount of total force that the rib
> fabric join can stand.
> a pound per square inch strength applied to a square inch can hold a
> pound
> a pound per square inch strength applied over a square foot can hold
> one hundred and fourty four pounds.
>
> Stealth Pilot
> Australia

I'll bite into this topic from an intellectual curiosity perspective.
What are the forces acting on a rag plane that would tug against the rib
bond? Source? Direction? Magnitude? How common are such bond failures?
What is the cause? Poor surface prep or other application shortcomings?
Deterioration of the glue or fabric over time? Other?

If I take a 3" long piece of tape and stick it on my desk, and a 12"
long piece and stick it next to it, does it take more force to peel the
longer one, or just more time? I'd say a wider one would stick more
assertively, but not a longer one. Is this at all analogous to what's
going on in an airplane, or way off?

Has this been studied like wing loading, with safety margins built in?
Does an airplane fall out of the sky if the fabric starts letting go? I
guess eventually it would, if pieces started tearing and departing the
airplane. That would disrupt the airflow, I imagine. There was a
discussion of punch testing a short time back. Is there also a "pull
test" to see whether the glue bonds are getting ready to fail?

These are the things that I think about while I struggle valiantly to
smash two rivets to the same shape and size.

[Stan Premo]

It might be like that old rag-top car we've seen tooling down the highway
with the fabric ballooning away from the metal top when the adhesive gave
way. The altered profile might change the lift characteristics of the wing
to some degree I suspect. I read somewhere that anything above 75 should be
rib stitched, but I'm no engineer.
> wrote in message
oups.com...
>I was reading some information on Fisher Celebrity builders websites
> and saw that one builder did not like the idea of glueing the fabric to
> the ribs as per the plans. The ribs on the Celebrity are very thin and
> he didn't think there was enough glue area for a satisfactory bond, so
> he rib stitched.
>
> I also recall reading somewhere that the glue area doesn't really
> affect the strength of the bond between the fabric and wood rib ( which
> I can't believe )
>
> I know the wing loading of the Celebrity is low compared to some of the
> more high performance bipes, but if the glue area is such a concern,
> wouldn't it be OK to just increase the rib capstrip width slightly to
> give more glueing area? Might only increase the whole airplane weight
> half a pound.
>
> Thoughts? Thanks
>
> Neal
>

[[email protected]]

wrote:
>
> ...
>
> I also recall reading somewhere that the glue area doesn't really
> affect the strength of the bond between the fabric and wood rib ( which
> I can't believe )
> ...


IIRC the explanation runs something like this:

When the fabric is glued to the rib some of the glue extends
slightly down the side of the rib/ribcap forming a sort of
bead or fillet, the rest forms a ribbon of glue between the
fabric and the ribcap.

As the fabric lifts from the rib the bead/fillet is stressed
in shear, while the ribbon is stressed in tension. The glue
is much stronger in shear than it is in tension, so if the
bead/fillet fails, the fabric will then peel away from the
broad flat surface of the rib cap. No matter how wide the
rib cap is, as the fabric peels the stress is concentrated
on a thin line adjacent to where the fabric has already
pulled away.

The bead/fillet is independent of the width of the rib/ribcap
hence the conclusion that the width does not matter.

Another conclusion is that, no matter how wide the rib caps
are, one should make sure the glue extends all the way to the
edge.

This suggests that the bond might be improved by running grooves
circumferentially around the rib caps. Sort of like what is
called 'tooth' in veneer work.


--

FF

[Morgans]

"Stan Premo" > wrote in message
...
> It might be like that old rag-top car we've seen tooling down the highway
> with the fabric ballooning away from the metal top when the adhesive gave
> way. The altered profile might change the lift characteristics of the
wing
> to some degree I suspect.

The fabric lifting off the top of the wing can, and has killed people. This
is still not to say that it has to be stitched.

If loads on the surface are low enough that the correctly glued fabric stays
place, then all is well. Just make sure the correct techniques are used,
and that loads are low enough!
--
Jim in NC

[Anthony W]

Morgans wrote:

>
>>It might be like that old rag-top car we've seen tooling down the highway
>>with the fabric ballooning away from the metal top when the adhesive gave
>>way. The altered profile might change the lift characteristics of the
> > wing
> <snip>
>
>
> The fabric lifting off the top of the wing can, and has killed people. This
> is still not to say that it has to be stitched.
>
> If loads on the surface are low enough that the correctly glued fabric stays
> place, then all is well. Just make sure the correct techniques are used,
> and that loads are low enough!

What about the 3rd option from the Tony Bengals books, covering the wing
with thin fiber glass cloth and resin?

I know it would make it harder to inspect the condition of the wood
years down the road (sky?) but it sounds like it would last longer in
the first place.

Tony

[[email protected]]

Anthony W wrote:
> Morgans wrote:
>
> >
> >>It might be like that old rag-top car we've seen tooling down the highway
> >>with the fabric ballooning away from the metal top when the adhesive gave
> >>way. The altered profile might change the lift characteristics of the
> > > wing
> > <snip>
> >
> >
> > The fabric lifting off the top of the wing can, and has killed people. This
> > is still not to say that it has to be stitched.
> >
> > If loads on the surface are low enough that the correctly glued fabric stays
> > place, then all is well. Just make sure the correct techniques are used,
> > and that loads are low enough!
>
> What about the 3rd option from the Tony Bengals books, covering the wing
> with thin fiber glass cloth and resin?

Just in case anyone wants to find his books its _Tony Bingelis.

Fiberglass wings are not fabric wings. You might as well say,
hey, why not cover them with aluminum sheet metal.

Also, I _think_ fiberglass wings will be heavier.

--

FF

[Anthony W]

wrote:

>>What about the 3rd option from the Tony Bengals books, covering the wing
>>with thin fiber glass cloth and resin?
>
>
> Just in case anyone wants to find his books its _Tony Bingelis.
>
> Fiberglass wings are not fabric wings. You might as well say,
> hey, why not cover them with aluminum sheet metal.
>
> Also, I _think_ fiberglass wings will be heavier.

I may have spelled his name wrong but from your answer, I don't think
you've read his books or at least this part.

Tony

[[email protected]]

Anthony W wrote:
> wrote:
>
> >>What about the 3rd option from the Tony Bengals books, covering the wing
> >>with thin fiber glass cloth and resin?
> >
> >
> > Just in case anyone wants to find his books its _Tony Bingelis.
> >
> > Fiberglass wings are not fabric wings. You might as well say,
> > hey, why not cover them with aluminum sheet metal.
> >
> > Also, I _think_ fiberglass wings will be heavier.
>
> I may have spelled his name wrong but from your answer, I don't think
> you've read his books or at least this part.
>

I have four of his books, and have read parts of each. Which
one are your thinking of?

Meaning no disrespect to Mr Bingelis, it remains the case that
fiberglass wings are not fabric wings.

--

FF

[Anthony W]

wrote:
> Anthony W wrote:
>
wrote:
>>
>>
>>>>What about the 3rd option from the Tony Bengals books, covering the wing
>>>>with thin fiber glass cloth and resin?
>>>
>>>
>>>Just in case anyone wants to find his books its _Tony Bingelis.
>>>
>>>Fiberglass wings are not fabric wings. You might as well say,
>>>hey, why not cover them with aluminum sheet metal.
>>>
>>>Also, I _think_ fiberglass wings will be heavier.
>>
>>I may have spelled his name wrong but from your answer, I don't think
>>you've read his books or at least this part.
>>
>
>
> I have four of his books, and have read parts of each. Which
> one are your thinking of?
>
> Meaning no disrespect to Mr Bingelis, it remains the case that
> fiberglass wings are not fabric wings.

I'd have to find it but I think it's in the yellow book. I only have 2
of the 4 in the series. I won a gift certificate to Amazon.com and they
didn't have anything else I wanted at the time for the $50 I had to spend.

Anyway Mr. Bingelis discuses covering wood wings and offers covering
them with thin glass cloth and resin as an option to regular fabric. As
I recall he says that if done right the weight is only slightly more and
it makes for stronger wings.

I've never built a plane, I was just asking if some one here had tried
this method recommended by known expert on the subject.

Tony

[Stealth Pilot]

On Thu, 13 Oct 2005 09:13:37 -0700, Smitty Two
> wrote:

>In article >,
> Stealth Pilot > wrote:
>
>
>> btw dont be beguiled by the semantics.
>> the glue strength doesnt change with the glue area since it is a force
>> per unit area measurement.
>> the glue area directly changes the amount of total force that the rib
>> fabric join can stand.
>> a pound per square inch strength applied to a square inch can hold a
>> pound
>> a pound per square inch strength applied over a square foot can hold
>> one hundred and fourty four pounds.
>>
>> Stealth Pilot
>> Australia
>
>I'll bite into this topic from an intellectual curiosity perspective.
>What are the forces acting on a rag plane that would tug against the rib
>bond? Source? Direction? Magnitude? How common are such bond failures?
>What is the cause? Poor surface prep or other application shortcomings?
>Deterioration of the glue or fabric over time? Other?
>
I'll reply for the other guys benefit. I dont know what you'll read
into this :-)

glue bonds fail over time from the stress rise at the edge of the
joint.

air pressure will create a force perpendicular to the surface.
have a look in a text at one of the manometer photos of a wing section
under test to get an idea of the pressure distribution.

the predominant cause of failure in fabric bonds is the reversing
loads created by turbulence from the slipstream off the prop. outside
of the slipstream competently bonded fabric seldom fails.
the fabric bond fails from the edge and slowly the failure creeps
inward across the joint. ribstitching in the area of the slipstream
works to correct the problem because it doesnt have stress risers
occurring at the edges of the thread.

my method of checking the stits fabric on my tailwind is to look
inside the tailcone out in the bright sunlight and pick the areas
where the uv opaquing was poorly done. I then make the "bird" with one
hand and walk along those areas banging the finger into the fabric as
hard as my hand will allow. If I ever get a puncture I'll initially
repair it. If I get areas of punctures then it is in for a refabric.
I've wanted to refabric the aircraft for a few years now but the stits
seems to have an infinite life. I cant detect any deterioration other
than in the visual appearance of the paint.

not a complete disertation but then the other guy wasnt asking much.
Stealth Pilot

[Stealth Pilot]

On 13 Oct 2005 20:26:10 -0700, wrote:

>
>Anthony W wrote:
>> wrote:
>>
>> >>What about the 3rd option from the Tony Bengals books, covering the wing
>> >>with thin fiber glass cloth and resin?
>> >
>> >
>> > Just in case anyone wants to find his books its _Tony Bingelis.
>> >
>> > Fiberglass wings are not fabric wings. You might as well say,
>> > hey, why not cover them with aluminum sheet metal.
>> >
>> > Also, I _think_ fiberglass wings will be heavier.
>>
>> I may have spelled his name wrong but from your answer, I don't think
>> you've read his books or at least this part.
>>
>
>I have four of his books, and have read parts of each. Which
>one are your thinking of?
>
>Meaning no disrespect to Mr Bingelis, it remains the case that
>fiberglass wings are not fabric wings.

are you sure?
razorback is a fabric system that uses fibreglass.
Stealth Pilot

[[email protected]]

Stealth Pilot wrote:
> On 13 Oct 2005 20:26:10 -0700, wrote:
>
> >
> >Anthony W wrote:
> >> wrote:
> >>
> >> >>What about the 3rd option from the Tony Bengals books, covering the wing
> >> >>with thin fiber glass cloth and resin?
> >> >
> >> >
> >> > Just in case anyone wants to find his books its _Tony Bingelis.
> >> >
> >> > Fiberglass wings are not fabric wings. You might as well say,
> >> > hey, why not cover them with aluminum sheet metal.
> >> >
> >> > Also, I _think_ fiberglass wings will be heavier.
> >>
> >> I may have spelled his name wrong but from your answer, I don't think
> >> you've read his books or at least this part.
> >>
> >
> >I have four of his books, and have read parts of each. Which
> >one are your thinking of?
> >
> >Meaning no disrespect to Mr Bingelis, it remains the case that
> >fiberglass wings are not fabric wings.
>
> are you sure?
> razorback is a fabric system that uses fibreglass.
> Stealth Pilot

Thanks. With a little googling I learned that Razorback is
fiberglass cloth filled with butyrate dope. I daresay that
is significanlty differant from fiberglass cloth filled with
epoxy or polyester resin.

Whether or not that makes a razorback wing a fiberglass wing
or a fabric wing would seem to be a matter of interpretation.
I guess I'd call it a hybrid.

Like Anthony W, I have not built a plane.

Last night I went through Bingelis' books and found that the
fiberglass section of the yellow book (Sportplane Construction
Techniques is the title IIRC) dealt with gas tanks, wheel pants,
cowls and such. He didn't really address wing covering in that
book.

In his blue book (Sportplane Builder) he has a Chapter near the
end on Dacron, but Chapter 5 is 'Fiberglass Tips' and has a section
'Fiberglass Your Bird'. This discusses using lightweight
fiberglass cloth and resin to cover a plywood fuselage, similar
to light boat construction. (BTW, there is a boatbuilding
technique called 'stich and glue' which looks to be adaptable
to stressed skin construction.) He says he first used the material
to cover the tailfeathers of an Emeraude, are those skinned with
plywood? Looking at photos on the net it appears that some rudders
are, and some aren't.

I would not rely on the book covers being the same color with
each printing, nor on my searching late last night being thorough.

But I don't think he suggests fiberglass cloth and resin over
ribs with nothing else underneath. ISTM that the cloth would
sag between the ribs and unlike the dope in the razorback system,
the curing resin would not draw it tight, unless you found
a resin that would shrink. Hmm, doesn't some poylester resin
shrink when it cures?

--

FF

[Ed Sullivan]

On 12 Oct 2005 14:33:47 -0700, wrote:


>
>Thoughts? Thanks
>
>Neal
>
On my 20 year old Jungster II I attached the fabric to 1" wide
capstrips. They were not varnished, they were generously coated with
Goodyear Pliobond. The wing was then covered and the ribs were brushed
over with acetone or MEK, I forget which to pull the adhesive up
through the fabric. So far so good and up to 170 mph in a dive.

The technique Tony Bingelis was refering to in his book was covering a
plywood covered aircraft in model airplane weight fiberglas. I used
the same material for the last layer on my wing and empennage tips as
well as the leading edge. Makes a real smooth finish without excess
filling.

Ed Sullivan

[[email protected]]

wrote:
> On 12 Oct 2005 14:33:47 -0700, wrote:
>
> >I was reading some information on Fisher Celebrity builders websites
> >and saw that one builder did not like the idea of glueing the fabric to
> >the ribs as per the plans. The ribs on the Celebrity are very thin and
> >he didn't think there was enough glue area for a satisfactory bond, so
> >he rib stitched.
>
> The Celebrity is a biplane with a top speed of 95 mph, right? Has it
> been a problem? Have any of the Celebrity's that had the fabric glued
> had the fabric come unstuck? Ever?
>

I vaguely remember reading in the FAA/NTSB archive about such an
incident. It was a while ago, so I may be a bit off. What I remember
was that the pilot was killed on impact and apparently he was aware of
some minor seperation and continued to fly the aircraft until it failed
catastrophically. Might have been another bird, but I think it was a
celebrity. I'm not 100% sure though. You might try searching the
accident database for the celebrity if you haven't already.

-Matt


> If not, why should it be considered an issue?
>
> On the other hand, if the guy just cannot live with attaching the
> fabric with glue, even if nothing bad has ever happened, he can
> certainly rib stitch. It won't hurt anything but his wallet, a bit,
> and add to the length of time building.
>
> Corky Scott

[[email protected]]

wrote:
> wrote:
> > On 12 Oct 2005 14:33:47 -0700, wrote:
> >
> > >I was reading some information on Fisher Celebrity builders websites
> > >and saw that one builder did not like the idea of glueing the fabric to
> > >the ribs as per the plans. The ribs on the Celebrity are very thin and
> > >he didn't think there was enough glue area for a satisfactory bond, so
> > >he rib stitched.
> >
> > The Celebrity is a biplane with a top speed of 95 mph, right? Has it
> > been a problem? Have any of the Celebrity's that had the fabric glued
> > had the fabric come unstuck? Ever?
> >
>
> I vaguely remember reading in the FAA/NTSB archive about such an
> incident. It was a while ago, so I may be a bit off. What I remember
> was that the pilot was killed on impact and apparently he was aware of
> some minor seperation and continued to fly the aircraft until it failed
> catastrophically. Might have been another bird, but I think it was a
> celebrity. I'm not 100% sure though. You might try searching the
> accident database for the celebrity if you haven't already.
>

That sounds pretty much like what happened to Steve Wittman.
He put off fixing the problem until after he got to Oshkosh.

--

FF

[[email protected]]

wrote:
> wrote:
> > On 12 Oct 2005 14:33:47 -0700, wrote:
> >
> > >I was reading some information on Fisher Celebrity builders websites
> > >and saw that one builder did not like the idea of glueing the fabric to
> > >the ribs as per the plans. The ribs on the Celebrity are very thin and
> > >he didn't think there was enough glue area for a satisfactory bond, so
> > >he rib stitched.
> >
> > The Celebrity is a biplane with a top speed of 95 mph, right? Has it
> > been a problem? Have any of the Celebrity's that had the fabric glued
> > had the fabric come unstuck? Ever?
> >
>
> I vaguely remember reading in the FAA/NTSB archive about such an
> incident. It was a while ago, so I may be a bit off. What I remember
> was that the pilot was killed on impact and apparently he was aware of
> some minor seperation and continued to fly the aircraft until it failed
> catastrophically. Might have been another bird, but I think it was a
> celebrity. I'm not 100% sure though. You might try searching the
> accident database for the celebrity if you haven't already.
>

That sounds pretty much like what happened to Steve Wittman.
He put off fixing the problem until after he got to Oshkosh.

--

FF

[Morgans]

> wrote

> I vaguely remember reading in the FAA/NTSB archive about such an
> incident. It was a while ago, so I may be a bit off. What I remember
> was that the pilot was killed on impact and apparently he was aware of
> some minor seperation and continued to fly the aircraft until it failed
> catastrophically. Might have been another bird, but I think it was a
> celebrity. I'm not 100% sure though. You might try searching the
> accident database for the celebrity if you haven't already.

I am not an authority on the facts, so I didn't bring up the name of the
incident that I was thinking of, but since nobody else with all of the facts
has, I will.

Steve Whitman(sp?), namesake of the OSH airport, racer, and designer of the
Tailwind (among others) was killed in such an unbonding incident. I don't
recall the details, but I recall that he did something wrong, or against
other's recommendations.

The planes he designed were much higher performance crafts than what the OP
was asking about. I'm sure he can google the details.
--
Jim in NC

[Peter Dohm]

> wrote in message
ups.com...
>
> That sounds pretty much like what happened to Steve Wittman.
> He put off fixing the problem until after he got to Oshkosh.
>
> --
>
> FF
>
Ok, I'm curious, since I haddn't heard this before, and it doesn't seem
to be part of the report (ATL95FA092) in the accident database.

That's really not too surprising, since the folks I knew who rushed off
to take part in the investigation regarded Steve Wittman as roughly
equal to Jesus of Nazareth...

At least hypothetically, delamination could have been detected in the
same manner on the O&O Special as on a composite aircraft--by
taping with a coin, or even a fingernail. However, Mr. Wittman was
not tall enough to do so on a plane larger than a Tailwind, and this
would appear far beyond the scope of a pre-flight inspection unless
one had some cause for suspicion; whether visual, hearsay, or some
anomoly on a previous flight.

Sooooo, tell us more...

Peter

[[email protected]]

Peter Dohm wrote:
> > wrote in message
> ups.com...
> >
> > That sounds pretty much like what happened to Steve Wittman.
> > He put off fixing the problem until after he got to Oshkosh.
> >
> > --
> >
> > FF
> >
> Ok, I'm curious, since I haddn't heard this before, and it doesn't seem
> to be part of the report (ATL95FA092) in the accident database.
>
> ...
>
> At least hypothetically, delamination could have been detected in the
> same manner on the O&O Special as on a composite aircraft--by
> taping with a coin, or even a fingernail. However, Mr. Wittman was
> not tall enough to do so on a plane larger than a Tailwind, and this
> would appear far beyond the scope of a pre-flight inspection unless
> one had some cause for suspicion; whether visual, hearsay, or some
> anomoly on a previous flight.
>
> Sooooo, tell us more...
>

I read, but do not recall where, perhaps you should DAGS in this
newsgroup, that someone who helped Mr Wittman prepare the
O & O for that last flight noticed a problem and tested the
fabric by pulling on it with a suction cup. Even though some
pulled loose, Mr Wittman did not think it was that serious
and the helper deferred to Mr Wittman in the matter.

That is not reflected in the NTSB report, but it may be that one
person helped him prepare the plane and a different person helped
with the pre-flight inspection per se.

--

FF

[[email protected]]

Ed Sullivan (a really big show tonight) wrote:
>
> ...
>
> The technique Tony Bingelis was refering to in his book was covering a
> plywood covered aircraft in model airplane weight fiberglas. I used
> the same material for the last layer on my wing and empennage tips as
> well as the leading edge. Makes a real smooth finish without excess
> filling.
>

Adding a layer of fiberglass must greatly inprove the stength,
durability, impact reisstance and water resistance, that is why
it's freqently done on plywood canoes, kayaks and small boats,
as well a producing a smooth finish.

If a smooth finish over wood is the only goal, then surely covering
with fiberglass is a lot of unecessary work. Fine Furniture makers
have been starting with rough wood and producing a very smooth
surface for a couple of hundred years. Grain filler and a cabinet
scraper (NOT a paint scraper) should do the trick for the airplane
builder.

--

FF

[Peter Dohm]

> wrote in message
oups.com...
>
> Peter Dohm wrote:
> > > wrote in message
> > ups.com...
> > >
> > > That sounds pretty much like what happened to Steve Wittman.
> > > He put off fixing the problem until after he got to Oshkosh.
> > >
> > > --
> > >
> > > FF
> > >
> > Ok, I'm curious, since I haddn't heard this before, and it doesn't seem
> > to be part of the report (ATL95FA092) in the accident database.
> >
> > ...
> >
> > At least hypothetically, delamination could have been detected in the
> > same manner on the O&O Special as on a composite aircraft--by
> > taping with a coin, or even a fingernail. However, Mr. Wittman was
> > not tall enough to do so on a plane larger than a Tailwind, and this
> > would appear far beyond the scope of a pre-flight inspection unless
> > one had some cause for suspicion; whether visual, hearsay, or some
> > anomoly on a previous flight.
> >
> > Sooooo, tell us more...
> >
>
> I read, but do not recall where, perhaps you should DAGS in this
> newsgroup, that someone who helped Mr Wittman prepare the
> O & O for that last flight noticed a problem and tested the
> fabric by pulling on it with a suction cup. Even though some
> pulled loose, Mr Wittman did not think it was that serious
> and the helper deferred to Mr Wittman in the matter.
>
> That is not reflected in the NTSB report, but it may be that one
> person helped him prepare the plane and a different person helped
> with the pre-flight inspection per se.
>
> --
>
> FF
>
Thanks, FF, that explains it. I don't personally know anyone who
wouldn't have deferred to Mr. Wittman on the matter He was the
designer, builder, and pilot of the plane and also highly regarded as
a guru in that type of construction.

It's interesting in that it provides a "quick and dirty" method of
non-destructive testing, and also a reminder to *really* understand
a manufacturer's recomendations for using or installing a product.

It was certainly unfortunate, but not nearly so bad as the prospect
of pining away in nursing home a few years later.

Peter

p.s.: Since I'm confident that I have a few years left; I'm gratefull
for one more tool (the suction cup) to check for latent defects.

[[email protected]]

Peter Dohm wrote:
>
> ...
>
>
> It's interesting in that it provides a "quick and dirty" method of
> non-destructive testing, and also a reminder to *really* understand
> a manufacturer's recomendations for using or installing a product.

I dimly recall that there was a way to measure how much force
it took to pull away the cloth, something more elaborate than
'feels like' but it has been a couple of years since I read that.

>
> It was certainly unfortunate, but not nearly so bad as the prospect
> of pining away in nursing home a few years later.
>

He wasn't flying alone.

[Peter Dohm]

> wrote in message
oups.com...
>
> Peter Dohm wrote:
> >
> > ...
> >
> >
> > It's interesting in that it provides a "quick and dirty" method of
> > non-destructive testing, and also a reminder to *really* understand
> > a manufacturer's recomendations for using or installing a product.
>
> I dimly recall that there was a way to measure how much force
> it took to pull away the cloth, something more elaborate than
> 'feels like' but it has been a couple of years since I read that.
>
Possibly a "fish scale" and some calibration data from Stits or a
similar source. In the event that I visit Sun n Fun this year, there
may be a source of further information. I have no present contact
with fabric and glue, but will try to alert chapter members who do.
> >
> > It was certainly unfortunate, but not nearly so bad as the prospect
> > of pining away in nursing home a few years later.
> >
>
> He wasn't flying alone.
>
Quite true.

An now a few more of us know one more thing to watch for.

The point that I did not state, and on which I'll try not to start a
rant, is that I little bit of fatalism is appropriate in aviation, driving,
bridge construction, warfare, mining, and nearly everything else
that we do. There are no guarantees, so you have to trust what
you believe is greater knowledge and experience. In this instance;
Mr. Wittman, Mrs. Wittman, and the "helper" all believed that Mr.
Wittman had the greater knowledge and experience and, in this
particular matter, he did not. As we say: "Stuff happens."

Peter

[[email protected]]

On 14 Oct 2005 17:34:46 -0700, wrote:

>> I vaguely remember reading in the FAA/NTSB archive about such an
>> incident. It was a while ago, so I may be a bit off. What I remember
>> was that the pilot was killed on impact and apparently he was aware of
>> some minor seperation and continued to fly the aircraft until it failed
>> catastrophically. Might have been another bird, but I think it was a
>> celebrity. I'm not 100% sure though. You might try searching the
>> accident database for the celebrity if you haven't already.
>>
>
>That sounds pretty much like what happened to Steve Wittman.
>He put off fixing the problem until after he got to Oshkosh.

I spoke with a pilot recently who is from Florida. Somehow Wittman's
accident came up and this pilot opined that while it's true that the
fabric appears to have delaminated from the wing thus causing the
catastrophic flutter that seperated the wing from the fuselage, he
thinks the Air Force had a hand in the accident. He, and some others
from his area, feel that wake turbulence may have jolted the wing into
flutter. There were military aircraft flying low level practice
missions in the area where he went down, according to this guy.

He didn't think the fabric would have delaminated without some kind of
jolt.

I don't know, it was an old airplane that had been sitting around for
a long time and it was a relatively fast cruiser. It may have been
possible for the fabric to rip loose without any help from close
passing B1's.

Corky Scott

[[email protected]]

wrote:
> On 14 Oct 2005 17:34:46 -0700, wrote:
>
> >> I vaguely remember reading in the FAA/NTSB archive about such an
> >> incident. It was a while ago, so I may be a bit off. What I remember
> >> was that the pilot was killed on impact and apparently he was aware of
> >> some minor seperation and continued to fly the aircraft until it failed
> >> catastrophically. Might have been another bird, but I think it was a
> >> celebrity. I'm not 100% sure though. You might try searching the
> >> accident database for the celebrity if you haven't already.
> >>
> >
> >That sounds pretty much like what happened to Steve Wittman.
> >He put off fixing the problem until after he got to Oshkosh.
>
> I spoke with a pilot recently who is from Florida. Somehow Wittman's
> accident came up and this pilot opined that while it's true that the
> fabric appears to have delaminated from the wing thus causing the
> catastrophic flutter that seperated the wing from the fuselage, he
> thinks the Air Force had a hand in the accident. He, and some others
> from his area, feel that wake turbulence may have jolted the wing into
> flutter. There were military aircraft flying low level practice
> missions in the area where he went down, according to this guy.

Prior to the release of the FAA report there was speculation about
that in the rec.aviation newsgroups:

http://groups.google.com/group/rec.aviation.homebuilt/msg/b3af292fbca61b4c?dmode=source&hl=en

And that an improper bolt may have been used in the horizontal
stabilizer:

http://groups.google.com/group/rec.aviation.homebuilt/msg/1e8420ab1c418928?dmode=source&hl=en

The FAA accident report (link appears earlier in this thread) refers
to both issues. They ruled out B1 turbulence and do not appear to
have drawn any conclusions as to the latter.

>
> He didn't think the fabric would have delaminated without some kind of
> jolt.

Respecfully, did he personally see the O & O special, ever?

>
> I don't know, it was an old airplane that had been sitting around for
> a long time and it was a relatively fast cruiser. It may have been
> possible for the fabric to rip loose without any help from close
> passing B1's.
>

--

FF

[Cy Galley]

Steve's plane was less than 10 years old I believe at the time of the
accident. Not very old as plane go.


> wrote in message
...
> On 14 Oct 2005 17:34:46 -0700, wrote:
>
>>> I vaguely remember reading in the FAA/NTSB archive about such an
>>> incident. It was a while ago, so I may be a bit off. What I remember
>>> was that the pilot was killed on impact and apparently he was aware of
>>> some minor seperation and continued to fly the aircraft until it failed
>>> catastrophically. Might have been another bird, but I think it was a
>>> celebrity. I'm not 100% sure though. You might try searching the
>>> accident database for the celebrity if you haven't already.
>>>
>>
>>That sounds pretty much like what happened to Steve Wittman.
>>He put off fixing the problem until after he got to Oshkosh.
>
> I spoke with a pilot recently who is from Florida. Somehow Wittman's
> accident came up and this pilot opined that while it's true that the
> fabric appears to have delaminated from the wing thus causing the
> catastrophic flutter that seperated the wing from the fuselage, he
> thinks the Air Force had a hand in the accident. He, and some others
> from his area, feel that wake turbulence may have jolted the wing into
> flutter. There were military aircraft flying low level practice
> missions in the area where he went down, according to this guy.
>
> He didn't think the fabric would have delaminated without some kind of
> jolt.
>
> I don't know, it was an old airplane that had been sitting around for
> a long time and it was a relatively fast cruiser. It may have been
> possible for the fabric to rip loose without any help from close
> passing B1's.
>
> Corky Scott

[Stealth Pilot]

On 14 Oct 2005 09:56:25 -0700, wrote:


>In his blue book (Sportplane Builder) he has a Chapter near the
>end on Dacron, but Chapter 5 is 'Fiberglass Tips' and has a section
>'Fiberglass Your Bird'. This discusses using lightweight
>fiberglass cloth and resin to cover a plywood fuselage, similar
>to light boat construction. (BTW, there is a boatbuilding
>technique called 'stich and glue' which looks to be adaptable
>to stressed skin construction.)

stitch and glue is used on the mirror dinghy. it works but I'd stick
with proven aircraft techniques because they build lighter.


>But I don't think he suggests fiberglass cloth and resin over
>ribs with nothing else underneath. ISTM that the cloth would
>sag between the ribs and unlike the dope in the razorback system,
>the curing resin would not draw it tight, unless you found
>a resin that would shrink. Hmm, doesn't some poylester resin
>shrink when it cures?

look in the eaa magazine archives for articles describing the building
of a one off homebuilt called "ol ironsides" that describes a sound
method of making fibreglass covering for a fuselage that is over a
truss wooden fuselage. afaik ol ironsides was basically a wooden
single seat Tailwind.

Stealth Pilot
ps
one of the advantages of definitive works like Tony's books is that
they rapidly bring everyone up to the state of the art.
the disadvantage only becomes evident after some time.
nobody moves past that standard for quite some time.

[Kyle Boatright]

"Morgans" > wrote in message
...
>
> > wrote
>
>> I vaguely remember reading in the FAA/NTSB archive about such an
>> incident. It was a while ago, so I may be a bit off. What I remember
>> was that the pilot was killed on impact and apparently he was aware of
>> some minor seperation and continued to fly the aircraft until it failed
>> catastrophically. Might have been another bird, but I think it was a
>> celebrity. I'm not 100% sure though. You might try searching the
>> accident database for the celebrity if you haven't already.
>
> I am not an authority on the facts, so I didn't bring up the name of the
> incident that I was thinking of, but since nobody else with all of the
> facts
> has, I will.
>
> Steve Whitman(sp?), namesake of the OSH airport, racer, and designer of
> the
> Tailwind (among others) was killed in such an unbonding incident. I don't
> recall the details, but I recall that he did something wrong, or against
> other's recommendations.

That is my recollection as well. IIRC, he mixed and matched covering
processes and product "A" didn't get a good bond to product "B". Eventually
the bond failed, leading to flutter and a structural failure.

> The planes he designed were much higher performance crafts than what the
> OP
> was asking about. I'm sure he can google the details.
> --
> Jim in NC

KB