Weight saving exercise.

I have to begin making a few decisions on how to drop a few pounds (off my
butt and my airplane!)
For one, I'm considering making the composite tank as outlined in Tony
Bengelis' book. This would be the foam/glass sandwich he describes. Questin
is, is it lighter than the aluminum tank specified in my plans? I'm sure
part of it is how much resin you lather on, but is it possible to save a
couple of pounds here? Leaving the wieght aside, it's an attractive looking
propostion. By the way, the tank is a removable wing tank, about 4'by 2' by
5".
Next, what's the lightest practical covering? Biplane, weighs about 1450
lbs, redlines at 150 mph. In other words, what's the lightest system for a
cub type machine?
Finally, Wheels and brakes. They need to be reasonably robust and the plans
call for cessna type axles, wheels and brakes, but can imake any
significant savings by subsitituting something else? I don't want to put
plastic wheelbarow whels on , by the way! I'm talking about maybe
substituting cub, luscombe,whatever might be suitable which will give me a
few pounds.
any suggestions aobut these or any other tricks anyone might know greatly
appreciated!

Hi,

I don't think you save weight by using glass/foam, maybe if you use the
Kevlar/glass combo fabric.

For wings use dacron 2,4 oz and not to much paint.

use a wood or composite prop not aluminum

for the rest of the body, use meat, fat, egg, fish, vegetable, fruit.
stay out of rice, potatoes, pasta, bread (Atkinson method)

Jan Carlsson
www.jcpropellerdesign.com


"Fortunat1" skrev i meddelandet
...
I have to begin making a few decisions on how to drop a few pounds (off my
butt and my airplane!)
For one, I'm considering making the composite tank as outlined in Tony
Bengelis' book. This would be the foam/glass sandwich he describes.
Questin
is, is it lighter than the aluminum tank specified in my plans? I'm sure
part of it is how much resin you lather on, but is it possible to save a
couple of pounds here? Leaving the wieght aside, it's an attractive
looking
propostion. By the way, the tank is a removable wing tank, about 4'by 2'
by
5".
Next, what's the lightest practical covering? Biplane, weighs about 1450
lbs, redlines at 150 mph. In other words, what's the lightest system for a
cub type machine?
Finally, Wheels and brakes. They need to be reasonably robust and the
plans
call for cessna type axles, wheels and brakes, but can imake any
significant savings by subsitituting something else? I don't want to put
plastic wheelbarow whels on , by the way! I'm talking about maybe
substituting cub, luscombe,whatever might be suitable which will give me a
few pounds.
any suggestions aobut these or any other tricks anyone might know greatly
appreciated!

"Jan Carlsson"
:

Hi,

I don't think you save weight by using glass/foam, maybe if you use
the Kevlar/glass combo fabric.

For wings use dacron 2,4 oz and not to much paint.

use a wood or composite prop not aluminum

for the rest of the body, use meat, fat, egg, fish, vegetable, fruit.
stay out of rice, potatoes, pasta, bread (Atkinson method)


He he, thanks,.

I've been poking around th eAircraft Spruce site trying to figure out how
much a bare composite tank is and it loks to be almost exactly the same as
an aluminum one. I might still do it because I don't realy want to build an
aluminum one and the composite loks easy. The prop's a done deal, though,
Fairly large Ham Standard ground adjustable! Very heavy. If I don't get the
performance out of it, I might try a wooden one though if this one doesn't
work out. The fabric and finish sound god though!

thanks

Bryan Martin
sednews:BE693745.3CE41%bryanmmartinNOSPAM@comcast. net:

You probably won't save any weight with a fiberglass tank. Homemade
fiberglass lay-ups tend to be a lot heavier than aluminum for the
equivalent strength. The big advantage of fiberglass isn't weight,
it's the ability to easily form it into complex shapes.

OK, thanks. I wasn't actually thinking of a layup, but a foam core
construction made of foam sheet coverd in two layers of glass cloth each
side amd made up into box. Looks like it should be light enough, but I
can't tell how much epoxy i'm going ot need. The tank would be about 23 Sq
feet in surface area, one side, of course, si double it and add a bit for
baffles and I need to glass and epoxy about 50 sq. feet of 1/4 inch foam.
any notion how much epoxy is needed? I've only ever done little patching
jobs with epoxy

You can probably make a little bigger tank in composite, I have made 2 using
wet lay-up over a foam plug, ((one with plastic cover material for
buildings) and one I put gasoline in the foam and scraped the gunk out) no
foam sandwich in the walls, and a couple bulkheads in the tank, and a large
sump with drain and outlet for the fuel line.

Used 3-4 layers of 300-400 gram fibre glass, the epoxy is about the same
amount as the glass.

Jan
"Fortunat1" skrev i meddelandet ...
Bryan Martin
sednews:BE693745.3CE41%bryanmmartinNOSPAM@comcast. net:

You probably won't save any weight with a fiberglass tank. Homemade
fiberglass lay-ups tend to be a lot heavier than aluminum for the
equivalent strength. The big advantage of fiberglass isn't weight,
it's the ability to easily form it into complex shapes.

OK, thanks. I wasn't actually thinking of a layup, but a foam core
construction made of foam sheet coverd in two layers of glass cloth each
side amd made up into box. Looks like it should be light enough, but I
can't tell how much epoxy i'm going ot need. The tank would be about 23 Sq
feet in surface area, one side, of course, si double it and add a bit for
baffles and I need to glass and epoxy about 50 sq. feet of 1/4 inch foam.
any notion how much epoxy is needed? I've only ever done little patching
jobs with epoxy

How did you get to this point in the first place, maybe based on that
we can make some suggestion. Was the design overweight by design or
was it over built? How close is the empty weight to that of the
prototype?

egroups.com:

How did you get to this point in the first place, maybe based on that
we can make some suggestion. Was the design overweight by design or
was it over built? How close is the empty weight to that of the
prototype?

I'm in the early stages and am trying to avoid some of the pitfalss of the
first time builder. So far, I'm doing well. The ribs (truss) are as light
as feathers with barely enough spare glue sticking out of the gussets to
show they're covered. My welds are good, so I won't be carrying around 50
lbs of extra rod when it's done, I hope, and I'm dodging all the popular
mods and sticking pretty much to plans. There's nothing wrong with the
design (Hatz), but I'm not going to overpower it and my local strip is only
500 yard long, with obstacles, so I just want to stay "ahead of the power
curve" from day one in every way possible. After all, I'm not going to be
able tocut things out so easily after it's finished! Previous builders
usually wind up with empty weights of about 950lbs, but it's possible to
build it as light as 860, so I'm going to shoot low.
got some good ideas here, too. I'm thinking the composite tank is probably
not the way to go now, so I'm going to have to learn to build an aluminum
tank..

Anyone know of a resource to show me how?

Richard Riley
:

On 25 Mar 2005 09:07:19 GMT, Fortunat1 wrote:

:Bryan Martin
:sednews:BE693745.3CE41%bryanmmartinNOSPAM@comcas t.net:
:
: You probably won't save any weight with a fiberglass tank. Homemade
: fiberglass lay-ups tend to be a lot heavier than aluminum for the
: equivalent strength. The big advantage of fiberglass isn't weight,
: it's the ability to easily form it into complex shapes.
:
:OK, thanks. I wasn't actually thinking of a layup, but a foam core
:construction made of foam sheet coverd in two layers of glass cloth
:each side amd made up into box. Looks like it should be light enough,
:but I can't tell how much epoxy i'm going ot need. The tank would be
:about 23 Sq feet in surface area, one side, of course, si double it
:and add a bit for baffles and I need to glass and epoxy about 50 sq.
:feet of 1/4 inch foam. any notion how much epoxy is needed? I've only
:ever done little patching jobs with epoxy

Figure, as a rule of thumb, the epoxy will weight 50-60% of the glass.
But for a tank, that fraction goes up, since you want the inside
laminate very wet and no leaking dry spots.

Aluminum will be lighter.


OK, thank you very much..

Sold.

"Jan Carlsson"
:

You can probably make a little bigger tank in composite, I have made 2
using wet lay-up over a foam plug, ((one with plastic cover material
for buildings) and one I put gasoline in the foam and scraped the gunk
out) no foam sandwich in the walls, and a couple bulkheads in the
tank, and a large sump with drain and outlet for the fuel line.

Used 3-4 layers of 300-400 gram fibre glass, the epoxy is about the
same amount as the glass.

OK thanks. Nice to have a few figures to work with. I can see there's no
weight advantage, definitely.

Thanks again to all! Any other weight saving suggestions welcome, though!

"Fortunat1" wrote in message

. . . so I'm going to have to learn to build an aluminum
tank..

Anyone know of a resource to show me how?

The books by Tony Bingelis have excellent tips on this.
http://www.amtbooks.com/sport_plane_...on_techniq.htm

Rich Shankland