Wrinkly flat panels

[[email protected]]

I've seen a few homebuilts with part of the fuselage panel that are flat
aluminum that are quite wrinkly and tend to "oil can" and make noise in
various flight attitudes. I haven't seen cross breaks used to stop this,
although it is used in duct work to stiffen flat panels. (cross breaks are
slight bends in the metal, done diagonally from corner to corner)

Another thought to reduce this noise is to spray urethane foam on the panels.
I know that this foam is combustable, but I figure for it to get on fire would
mean the pilot and passenger cabin is already engulfed, so it wouldn't really
matter.

What do you think?

thanks,
tom pettit

[Richard Riley]

On Wed, 25 Feb 2004 00:19:12 GMT, wrote:

:I've seen a few homebuilts with part of the fuselage panel that are flat
:aluminum that are quite wrinkly and tend to "oil can" and make noise in
:various flight attitudes. I haven't seen cross breaks used to stop this,
:although it is used in duct work to stiffen flat panels. (cross breaks are
:slight bends in the metal, done diagonally from corner to corner)
:
:Another thought to reduce this noise is to spray urethane foam on the panels.
:I know that this foam is combustable, but I figure for it to get on fire would
:mean the pilot and passenger cabin is already engulfed, so it wouldn't really
:matter.

Check out

http://www.eng.fiu.edu/pantherskin/

It's very interesting stuff. Especially the burn through test.

[jls]

> wrote in message
...
> I've seen a few homebuilts with part of the fuselage panel that are flat
> aluminum that are quite wrinkly and tend to "oil can" and make noise in
> various flight attitudes. I haven't seen cross breaks used to stop this,
> although it is used in duct work to stiffen flat panels. (cross breaks
are
> slight bends in the metal, done diagonally from corner to corner)
>
> Another thought to reduce this noise is to spray urethane foam on the
panels.
> I know that this foam is combustable, but I figure for it to get on fire
would
> mean the pilot and passenger cabin is already engulfed, so it wouldn't
really
> matter.
>
> What do you think?
>
> thanks,
> tom pettit

A stiffening bead pressed into the panel or aluminum channel or angle
riveted to the back of the panel. My old Taylorcraft has half-circle
pressed beads on the firewall to stiffen it, and I notice the old Cessna I
have the cowl off of has a flange running horizontally across the middle of
the firewall, plus a few other neat stiffening devices. That stiffens it
for you. You can countersink the rivets for appearance's sake if you wish.

Stiffening a panel of fiberglas is great fun: all you have to do is make a
sandwich with foam in between, the thicker the foam the stiffer. As a
matter of fact as the thickness increases the stiffness and strength go up
at a staggering rate. There are formulas for that and not being a
mathematician I'd best not delve into the theory of beams but if you double
the height of a beam you have increased the stiffness and strength of the
beam by exponents of the increase in height. Let Billy B. Badd explain it
to you in his most inimitable articulate way.

[Chris Batcheller]

The solution is simple. Cut the panel from 0.090 2024. The panel will
never wrinkle. Then paint the panel with an epoxy based paint. It will look
great for years.

We have them CNC machined all the time and they look great. email me if you
need me to set you up with a place that can do that.

Thanks, Chris

> wrote in message
...
> I've seen a few homebuilts with part of the fuselage panel that are flat
> aluminum that are quite wrinkly and tend to "oil can" and make noise in
> various flight attitudes. I haven't seen cross breaks used to stop this,
> although it is used in duct work to stiffen flat panels. (cross breaks
are
> slight bends in the metal, done diagonally from corner to corner)
>
> Another thought to reduce this noise is to spray urethane foam on the
panels.
> I know that this foam is combustable, but I figure for it to get on fire
would
> mean the pilot and passenger cabin is already engulfed, so it wouldn't
really
> matter.
>
> What do you think?
>
> thanks,
> tom pettit

[Wright1902Glider]

Curiously enough, I've seen pannel wrinkling on the front end of a B-52!

Harry

[Bob Chilcoat]

The stiffness goes up by the third power if the thickness. Double the
thickness of a plate, and it's eight times as stiff.

--
Bob (Chief Pilot, White Knuckle Airways)


" jls" > wrote in message
. ..
>
> > wrote in message
> ...
> > I've seen a few homebuilts with part of the fuselage panel that are flat
> > aluminum that are quite wrinkly and tend to "oil can" and make noise in
> > various flight attitudes. I haven't seen cross breaks used to stop
this,
> > although it is used in duct work to stiffen flat panels. (cross breaks
> are
> > slight bends in the metal, done diagonally from corner to corner)
> >
> > Another thought to reduce this noise is to spray urethane foam on the
> panels.
> > I know that this foam is combustable, but I figure for it to get on fire
> would
> > mean the pilot and passenger cabin is already engulfed, so it wouldn't
> really
> > matter.
> >
> > What do you think?
> >
> > thanks,
> > tom pettit
>
> A stiffening bead pressed into the panel or aluminum channel or angle
> riveted to the back of the panel. My old Taylorcraft has half-circle
> pressed beads on the firewall to stiffen it, and I notice the old Cessna I
> have the cowl off of has a flange running horizontally across the middle
of
> the firewall, plus a few other neat stiffening devices. That stiffens it
> for you. You can countersink the rivets for appearance's sake if you
wish.
>
> Stiffening a panel of fiberglas is great fun: all you have to do is make
a
> sandwich with foam in between, the thicker the foam the stiffer. As a
> matter of fact as the thickness increases the stiffness and strength go up
> at a staggering rate. There are formulas for that and not being a
> mathematician I'd best not delve into the theory of beams but if you
double
> the height of a beam you have increased the stiffness and strength of the
> beam by exponents of the increase in height. Let Billy B. Badd explain it
> to you in his most inimitable articulate way.
>
>

[Bob Kuykendall]

Earlier, "Chris Batcheller" > wrote:

> The solution is simple. Cut the panel from 0.090 2024...

I think that the original poster was using the term "panel" in a
somewhat generic sense, and not necessarily to refer to an instrument
panel. But that was the way I first read it, too.

Thanks, and best regards to all

Bob K.

[[email protected]]

Howdy All,

Thanks for your thoutful replies. They seem to fall into three main ideas:

Thicker panels:
yeah. This will work, but for exterior fuselage panels, it would be
prohibitively heavy. I'll pass.

Building in some kind of "upset":
This will work. Breaks, as I described will make the panels stiffer. Another
poster suggested rolling in ridges that would stiffen the panel. These would
look kind of goofy, and have a small drag effect. I think I'll pass.

Spraying a urethane foam on the inside:
This will stiffen the panel and improve the noise level inside the aircraft.
It would require a fire rated foam such as "gator skin". Other are
available. I'm leaning this way.

Thanks to all,
tom pettit

[Ernest Christley]

wrote:
> Howdy All,
>
>
> Building in some kind of "upset":
> This will work. Breaks, as I described will make the panels stiffer. Another
> poster suggested rolling in ridges that would stiffen the panel. These would
> look kind of goofy, and have a small drag effect. I think I'll pass.
>
> tom pettit

Tom, your plane, and you'll do as you please, but I don't think it would
have to add a measurable amount of drag or look goofy. I'm thinking of
a WW2 Japanese rising sun motif, starting at the center or the front
edge and expanding toward the back.

Aaah, if there were only time to build every iteration of airplane that
I could dream up.

--
http://www.ernest.isa-geek.org/
"Ignorance is mankinds normal state,
alleviated by information and experience."
Veeduber

[Richard Lamb]

wrote:
>
> Howdy All,
>
> Thanks for your thoutful replies. They seem to fall into three main ideas:
>
> Thicker panels:
> yeah. This will work, but for exterior fuselage panels, it would be
> prohibitively heavy. I'll pass.
>
> Building in some kind of "upset":
> This will work. Breaks, as I described will make the panels stiffer. Another
> poster suggested rolling in ridges that would stiffen the panel. These would
> look kind of goofy, and have a small drag effect. I think I'll pass.
>
> Spraying a urethane foam on the inside:
> This will stiffen the panel and improve the noise level inside the aircraft.
> It would require a fire rated foam such as "gator skin". Other are
> available. I'm leaning this way.
>
> Thanks to all,
> tom pettit

Lean back the other way some, Tom.
You are about to fall off of something here...

Filling large cavities with foam may be great for boats,
but don't do it to a metal airplane.

The lightest mix you'll get will be at least 3 pounds per cubic foot,
minimum.
And you'll need to pull a light vacuum to get that repeatably.

The foam will also continue to expand long after the skin has bulged way
outta shape.

Better solutions:

Deeply curved panels an not so susceptible to oil canning by nature of
their shape.
But that's a preliminary design issue, not an add on.

Better support inside will help reduce skin wrinkling and noise.
Closer spaced ribs, a cleverly placed stringer here or there?

I think the correct answer is thicker skin.

Increasing skin thickness a few thousandths will make a stiffer panel at
a fraction
of the weight of extra structure - or a fifty emergency flotation.


Now, may I suggest you contact the original designer with this question?

Because something as simple sounding as increasing skin thickness can
have snowball
effects on light structures.

In my book, that's considered a bad thing.

Richard

[[email protected]]

In article >, Richard Lamb > wrote:

>>
>> Spraying a urethane foam on the inside:
>> This will stiffen the panel and improve the noise level inside the aircraft.
>> It would require a fire rated foam such as "gator skin". Other are
>> available. I'm leaning this way.
>>
>> Thanks to all,
>> tom pettit
>
>Lean back the other way some, Tom.
>You are about to fall off of something here...
>
>Filling large cavities with foam may be great for boats,
>but don't do it to a metal airplane.
>
>The lightest mix you'll get will be at least 3 pounds per cubic foot,
>minimum.

>Richard

Sorry I wasn't clearer on my intention. I'd only spray about an inch on the
panels. Not much weight, and still get significant damping.

tom

[Blueskies]

ala TriMotor - corrugations

--
Dan D.



..
> wrote in message ...
> Howdy All,
>
> Thanks for your thoutful replies. They seem to fall into three main ideas:
>
> Thicker panels:
> yeah. This will work, but for exterior fuselage panels, it would be
> prohibitively heavy. I'll pass.
>
> Building in some kind of "upset":
> This will work. Breaks, as I described will make the panels stiffer. Another
> poster suggested rolling in ridges that would stiffen the panel. These would
> look kind of goofy, and have a small drag effect. I think I'll pass.
>
> Spraying a urethane foam on the inside:
> This will stiffen the panel and improve the noise level inside the aircraft.
> It would require a fire rated foam such as "gator skin". Other are
> available. I'm leaning this way.
>
> Thanks to all,
> tom pettit

[Richard Lamb]

Blueskies wrote:
>
> ala TriMotor - corrugations
>
> --
> Dan D.
>

Absolutely.

MUCH thicker skins :)

Rihcard

[Richard Lamb]

wrote:
>
> In article >, Richard Lamb > wrote:
>
> >>
> >> Spraying a urethane foam on the inside:
> >> This will stiffen the panel and improve the noise level inside the aircraft.
> >> It would require a fire rated foam such as "gator skin". Other are
> >> available. I'm leaning this way.
> >>
> >> Thanks to all,
> >> tom pettit
> >
> >Lean back the other way some, Tom.
> >You are about to fall off of something here...
> >
> >Filling large cavities with foam may be great for boats,
> >but don't do it to a metal airplane.
> >
> >The lightest mix you'll get will be at least 3 pounds per cubic foot,
> >minimum.
>
> >Richard
>
> Sorry I wasn't clearer on my intention. I'd only spray about an inch on the
> panels. Not much weight, and still get significant damping.
>
> tom

Balderdash, tom.

I think you are blowing in my ear.

First, just how do you expect to "spray on" a 1 inch thick layer
of foam INSIDE a wing? I can't do it, and I can do anything
(with Duct tape!).

Second, a 100 square foot wing is 14,400 square inches.
One inch thick is 14,400 CUBIC inches, or 8.3 cubic feet.
Top and bottom skins give 28,800 cubic inches or 16.6 cuft.

At the mythical 3 lb/ft^3, that's 50 pounds.

Sorry dude, that boat don't float...

[[email protected]]

In article >, Richard Lamb > wrote:
wrote:
>>
>> In article >, Richard Lamb
> > wrote:
>>
>> >>
>> >> Spraying a urethane foam on the inside:
>> >> This will stiffen the panel and improve the noise level inside the
> aircraft.
>> >> It would require a fire rated foam such as "gator skin". Other are
>> >> available. I'm leaning this way.
>> >>
>> >> Thanks to all,
>> >> tom pettit
>> >
>> >Lean back the other way some, Tom.
>> >You are about to fall off of something here...
>> >
>> >Filling large cavities with foam may be great for boats,
>> >but don't do it to a metal airplane.
>> >
>> >The lightest mix you'll get will be at least 3 pounds per cubic foot,
>> >minimum.
>>
>> >Richard
>>
>> Sorry I wasn't clearer on my intention. I'd only spray about an inch on the
>> panels. Not much weight, and still get significant damping.
>>
>> tom
>
>Balderdash, tom.
>
>I think you are blowing in my ear.
>
>First, just how do you expect to "spray on" a 1 inch thick layer
>of foam INSIDE a wing? I can't do it, and I can do anything
>(with Duct tape!).
>
>Second, a 100 square foot wing is 14,400 square inches.
>One inch thick is 14,400 CUBIC inches, or 8.3 cubic feet.
>Top and bottom skins give 28,800 cubic inches or 16.6 cuft.
>
>At the mythical 3 lb/ft^3, that's 50 pounds.
>
>Sorry dude, that boat don't float...

Yeah it will. 8^) I was talking about flat panels on the fuselage. The
Zenith CH701 I would like to build has about 60 square feet of fuselage area
behind the cabin. At one inch, that amounts to 5 cubic feet. One website I
visited that made fire retardant spray urethane foam says 1.75 pounds per
cubic foot, so the weight of this addition would be less than nine pounds.

By the way, I don't know you well enough to blow in your ear.

Regards,

tom

[[email protected]]

In article >, "Blueskies" > wrote:
>ala TriMotor - corrugations
>
I kind of like the idea of corregations. Any ideas on how to accomplish them?

thanks,
tom

[Richard Lamb]

wrote:
> >
> >At the mythical 3 lb/ft^3, that's 50 pounds.
> >
> >Sorry dude, that boat don't float...
>
> Yeah it will. 8^) I was talking about flat panels on the fuselage. The
> Zenith CH701 I would like to build has about 60 square feet of fuselage area
> behind the cabin. At one inch, that amounts to 5 cubic feet. One website I
> visited that made fire retardant spray urethane foam says 1.75 pounds per
> cubic foot, so the weight of this addition would be less than nine pounds.
>
> By the way, I don't know you well enough to blow in your ear.
>
> Regards,
>
> tom

No no no no no noooo.

Ok, a different offering?

Look around for some light weight sound deadening material.
It's right about 1/8" thick and either has a self stick backing
or can be stuck in place with probond.

(That's the way my neighbor did his 601-HDS anyway).

You really don't need to completely cover the area to reduce rattling.
A wide strip across the panel can be as effective.


Lastly, check that fire proof foam for "frangibility". (:^)

And how well it doesn't stick to bare aluminum?

You may find your fuselage is soon full of white fluff...



Richard

[Tim Ward]

> wrote in message
...
<snip of misunderstanding>
>>
> >> Sorry I wasn't clearer on my intention. I'd only spray about an inch
on the
> >> panels. Not much weight, and still get significant damping.
> >>
> >> tom
> >
> >Balderdash, tom.
> >
> >I think you are blowing in my ear.
> >
> >First, just how do you expect to "spray on" a 1 inch thick layer
> >of foam INSIDE a wing? I can't do it, and I can do anything
> >(with Duct tape!).
> >
> >Second, a 100 square foot wing is 14,400 square inches.
> >One inch thick is 14,400 CUBIC inches, or 8.3 cubic feet.
> >Top and bottom skins give 28,800 cubic inches or 16.6 cuft.
> >
> >At the mythical 3 lb/ft^3, that's 50 pounds.
> >
> >Sorry dude, that boat don't float...
>
> Yeah it will. 8^) I was talking about flat panels on the fuselage. The
> Zenith CH701 I would like to build has about 60 square feet of fuselage
area
> behind the cabin. At one inch, that amounts to 5 cubic feet. One website
I
> visited that made fire retardant spray urethane foam says 1.75 pounds per
> cubic foot, so the weight of this addition would be less than nine pounds.

If the panels are really flat, then why spray it on? Low density foam is
available in sheets. I'll bet the consistency is better than you can get
from a can. Bond it on before you rivet. It shouldn't have to go all the
way to the edges to prevent the oilcanning.

It looks like for the 9 lb weight penalty you could increase the thickness
of just those panels by about .010 inches (.15 lbs/sq ft). That would make
it less likely to oilcan and stronger.

Does the foam really need to be continuous? Why not just bond some foam
stiffeners to the inside of the panel every six inches or so? The HP-18
sailplane wing is made from 1/2" foam on four inch centers. That technique
might be more anechoic than a smooth continuous foam surface, too. You
could taper the stiffeners to be thicker in the center of the panel, and get
more stiffness/unit weight that way.

An interesting way to bond the stiffeners might be to use 3M VHB (Very High
Bond) double stick tape. It's used to bond side panels on truck and trailer
bodies. Fast and no goop.

Tim Ward

[[email protected]]

In article >, Richard Lamb > wrote:

>Ok, a different offering?
>
>Look around for some light weight sound deadening material.
>It's right about 1/8" thick and either has a self stick backing
>or can be stuck in place with probond.
>
>(That's the way my neighbor did his 601-HDS anyway).
>
>You really don't need to completely cover the area to reduce rattling.
>A wide strip across the panel can be as effective.
>
>Lastly, check that fire proof foam for "frangibility". (:^)
>
>And how well it doesn't stick to bare aluminum?
>
>You may find your fuselage is soon full of white fluff...
>
>Richard

The stuff sticks amazingly well to almost anything. It is quite tough. I
guess if it started flaking off, I could cut a hole in the back and start sky
writing with the trail of white flakes.

Probably the premade dampening material would be most practical. I have used
them before. The better performing ones are almost as heavy as the foam,
though.

tom

[Richard Lamb]

wrote:
>
> In article >, Richard Lamb > wrote:
>
> >Ok, a different offering?
> >
> >Look around for some light weight sound deadening material.
> >It's right about 1/8" thick and either has a self stick backing
> >or can be stuck in place with probond.
> >
> >(That's the way my neighbor did his 601-HDS anyway).
> >
> >You really don't need to completely cover the area to reduce rattling.
> >A wide strip across the panel can be as effective.
> >
> >Lastly, check that fire proof foam for "frangibility". (:^)
> >
> >And how well it doesn't stick to bare aluminum?
> >
> >You may find your fuselage is soon full of white fluff...
> >
> >Richard
>
> The stuff sticks amazingly well to almost anything. It is quite tough. I
> guess if it started flaking off, I could cut a hole in the back and start sky
> writing with the trail of white flakes.
>
> Probably the premade dampening material would be most practical. I have used
> them before. The better performing ones are almost as heavy as the foam,
> though.
>
> tom

Certainly neater :^)

It really doesn't take that much material to damp the flat panel
rattling and oil canning.

If I'm not mistaken, this is the same kind of fire proof foam that was
used in the World Trade center to protect the steel structure from fire.
Too much was knocked loose during the impact.
The rest is history...

I'd expect the vibration (and expecially local vibratin (oil canning?))
would play hell with sprayed on foam...

So, have you started on the Zodiac yet?

Richard

[Blueskies]

I saw a set of rollers with the corrugation profiles in them, and the 2024 was 'simply' hand cranked between them. Once
you have the rollers is should be pretty easy, but getting the rollers...

They crank out roof gutters from the back of vans on the building site, maybe someone knows someone who has an old
gutter rig...

--
Dan D.



..
> wrote in message ...
> In article >, "Blueskies" > wrote:
> >ala TriMotor - corrugations
> >
> I kind of like the idea of corregations. Any ideas on how to accomplish them?
>
> thanks,
> tom

[Blueskies]

How about cork? Probably too heavy...

--
Dan D.



..
"Tim Ward" > wrote in message ...
>
> > wrote in message
> ...
> <snip of misunderstanding>
> >>
> > >> Sorry I wasn't clearer on my intention. I'd only spray about an inch
> on the
> > >> panels. Not much weight, and still get significant damping.
> > >>
> > >> tom
> > >
> > >Balderdash, tom.
> > >
> > >I think you are blowing in my ear.
> > >
> > >First, just how do you expect to "spray on" a 1 inch thick layer
> > >of foam INSIDE a wing? I can't do it, and I can do anything
> > >(with Duct tape!).
> > >
> > >Second, a 100 square foot wing is 14,400 square inches.
> > >One inch thick is 14,400 CUBIC inches, or 8.3 cubic feet.
> > >Top and bottom skins give 28,800 cubic inches or 16.6 cuft.
> > >
> > >At the mythical 3 lb/ft^3, that's 50 pounds.
> > >
> > >Sorry dude, that boat don't float...
> >
> > Yeah it will. 8^) I was talking about flat panels on the fuselage. The
> > Zenith CH701 I would like to build has about 60 square feet of fuselage
> area
> > behind the cabin. At one inch, that amounts to 5 cubic feet. One website
> I
> > visited that made fire retardant spray urethane foam says 1.75 pounds per
> > cubic foot, so the weight of this addition would be less than nine pounds.
>
> If the panels are really flat, then why spray it on? Low density foam is
> available in sheets. I'll bet the consistency is better than you can get
> from a can. Bond it on before you rivet. It shouldn't have to go all the
> way to the edges to prevent the oilcanning.
>
> It looks like for the 9 lb weight penalty you could increase the thickness
> of just those panels by about .010 inches (.15 lbs/sq ft). That would make
> it less likely to oilcan and stronger.
>
> Does the foam really need to be continuous? Why not just bond some foam
> stiffeners to the inside of the panel every six inches or so? The HP-18
> sailplane wing is made from 1/2" foam on four inch centers. That technique
> might be more anechoic than a smooth continuous foam surface, too. You
> could taper the stiffeners to be thicker in the center of the panel, and get
> more stiffness/unit weight that way.
>
> An interesting way to bond the stiffeners might be to use 3M VHB (Very High
> Bond) double stick tape. It's used to bond side panels on truck and trailer
> bodies. Fast and no goop.
>
> Tim Ward
>
>
>
>

[Ernest Christley]

Blueskies wrote:
> How about cork? Probably too heavy...
>
And absorbs water. If it wasn't heavy when you put it in, it will be
after you fly through the first cloud. Whatever you use, make sure it is
HYDROPHOBIC

(a word I learned about in RAH)

--
http://www.ernest.isa-geek.org/
"Ignorance is mankinds normal state,
alleviated by information and experience."
Veeduber

[Del Rawlins]

Why not just buy a better headset? That ought to take care of any noise
from the sheetmetal and it won't add a bunch of weight and potential for
hidden corrosion to form under the deadening material.

I thought this discussion was about a bush plane? All of the serious
bush pilots that I know strip all of that crap OUT of their airplanes if
possible.

----------------------------------------------------
Del Rawlins-
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/

[Richard Lamb]

Del Rawlins wrote:
>
> Why not just buy a better headset? That ought to take care of any noise
> from the sheetmetal and it won't add a bunch of weight and potential for
> hidden corrosion to form under the deadening material.
>
> I thought this discussion was about a bush plane? All of the serious
> bush pilots that I know strip all of that crap OUT of their airplanes if
> possible.
>
> ----------------------------------------------------
> Del Rawlins-
> Remove _kills_spammers_ to reply via email.
> Unofficial Bearhawk FAQ website:
> http://www.rawlinsbrothers.org/bhfaq/

I thought it was about a Zodiac, but i've been wrong before...

But a Bush plane with rattle padding?


File under Hard Lessons Learned:

How important it is - and how hard it is -
to keep excess weight OUT of an airplane.

Temper foam is a great example.

This is for sure and certain the most comfortable stuff imaginable
short of free fall,

but the WEIGHT!

Padding a pair of bucket seats can add 30 pounds to the empty weight
of the airplane.

Ed Heineman would tell it loud and clear...
Simplacate rather than complicate.
Add lightness rather than heaviness.


Richard

[Del Rawlins]

In > Richard Lamb wrote:

> I thought it was about a Zodiac, but i've been wrong before...

Could have sworn they was talking about a CH701 STOL.

----------------------------------------------------
Del Rawlins-
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/

[[email protected]]

In article >, Del Rawlins > wrote:
>In > Richard Lamb wrote:
>
>> I thought it was about a Zodiac, but i've been wrong before...
>
>Could have sworn they was talking about a CH701 STOL.
>

I was talking about a CH701 rear fuselage. I agree that you should lighten
and simplify whenever possible. One reason not to do anything is that the
panels make quite a racket as buffeting occurs near stall. Maybe this is just
another genius of Chris Heinz?

thanks everybody for the discussion

tom

[Blueskies]

massophobic?

--
Dan D.



..
"Ernest Christley" > wrote in message . com...
> Blueskies wrote:
> > How about cork? Probably too heavy...
> >
> And absorbs water. If it wasn't heavy when you put it in, it will be
> after you fly through the first cloud. Whatever you use, make sure it is
> HYDROPHOBIC
>
> (a word I learned about in RAH)
>
> --
> http://www.ernest.isa-geek.org/
> "Ignorance is mankinds normal state,
> alleviated by information and experience."
> Veeduber