Something to measure physical pressure.

I want to make several samples of materials for covering my plane,
(plywood, composite, ceconite, etc....)
And I would like to find the difference with some kind of scale or
pressure meter to find the breaking points. Has anyone done this?
Lou

Is this for structural or non-structural covering? Each of the listed
material have significant
differences in their properties, so the use really needs to be defined
first. The intended use
is going to help define what materials you can use and in what grades
or forms or thickness,
or orientations. For example, composites for structural applications
are going to be laid up
and reinforced one way, so that they take the designed loads without
failure, while those parts
that are things like fairings, hatches ect. are going to be done
another way.

A good example is my Fairchild. It uses ceoconite as a structural
cover in some places, but
others, it is used as a surface protector. Same material, but
completely different uses and
application methods.

Craig C.

Well,,,,,,,,,,, at this point I'll have to say half and half.
The plans call for plywood over the ribs of the wings, structural.
the other parts are to cover the fuselage but the strutural is taken
care of on the inside.
Lou

For the fuselage, I'd stick with either aircraft or marine grade ply
for glue strength between plies.
If it's all flat areas, then 90 deg. layups are going to be the least
expensive and should work fine. If there are curves
then you are probably going to be limited to using aircraft grade with
45 deg layups. Do the
prints give you any guidence on thicknesses to use for the various
areas? If so, then there are
tables out there that give the various strength data vs the number of
plies vs the ply materials. They
also give the testing method used to generate the data. For fabric,
the Maule tester is the accepted
method. Ply is done by tension and twist test if I remember correctly,
coupled with steam testing of
the bonding agent. Composite is done by tension, compression and
impact tests. Tension and
compression tests are reasonable easy to duplicate, impact can be done
too, but is most likely
going to be a bit more subjective without a decent lab setup.

When in doubt, talk with the designer is the best advice. Unless there
is a complete egineering
workup with the design, that's about the only way to know why the
particular material selections.

Food for thought...

Craig C.

"Lou" wrote in message
oups.com...
Well,,,,,,,,,,, at this point I'll have to say half and half.
The plans call for plywood over the ribs of the wings, structural.
the other parts are to cover the fuselage but the strutural is taken
care of on the inside.
Lou

I did it with different fiberglass years ago. I made lay ups with different
types and amounts of glass cloth. I cut my samples in 1" wide coupons and
took them to a testing company simply chosen from the phone book. Since I
didn't require any written reports with the test results, they did it
extremely cheap. I think the pulled 8 coupons for $20, in about 1985.
Roughly $40 today.

"Lou" wrote in message
ups.com...
I want to make several samples of materials for covering my plane,
(plywood, composite, ceconite, etc....)
And I would like to find the difference with some kind of scale or
pressure meter to find the breaking points. Has anyone done this?
Lou


See http://www.hpaircraft.com/hp-24/update_22_oct_07.htm for pictures of the
"Break-A-Tron"

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

That will break it, but will it measure?

On Oct 29, 4:09 pm, Lou wrote:
That will break it, but will it measure?

http://www.youtube.com/watch?v=ZyVD0FBLiFQ

On Sun, 28 Oct 2007 17:34:42 -0700, Lou wrote:

I want to make several samples of materials for covering my plane,
(plywood, composite, ceconite, etc....)
And I would like to find the difference with some kind of scale or
pressure meter to find the breaking points. Has anyone done this?

The problem is, what question are you really asking?
In the labs we made coupons that tested tensile strength and
elongation in different planes such as pull yield, compression and
perpendicular to the surface. If it's shear then you have to define
over what length. If it's a pressure yield, over what area and how is
it distributed.

Many labs have the equipment to do the tests, but the problem is
defining what tests need to be done to display the pertinent results.
IOW, what strength and in what plane/axis, or what information do you
really need?

Roger (K8RI)
Lou

On Mon, 29 Oct 2007 16:09:47 -0700, Lou wrote:

That will break it, but will it measure?
Even then does it give results that are appropriate?
It appears to give tensile strength in pull, but that is only
indirectly related to aircraft skin strength.

Roger (K8RI)