Building a composite spar?

Morgans wrote:
"dirigible designer" wrote in message

Now I just have to figger out how to get those layers of
fiberglass, (matt and cloth), on the inside of the hollow triangular
spar 8-]

Use the opposite of vacuum bagging; pressure bag it.

Make up glass cloth with epoxy squeegee into it, then lay it on the foam,
lay on the release cloth, make up the pressure bag, fold it all up, bind it
on the outside with tape or something, then put the pressure to the bag and
let it cure.

You will have to cut an inspection panel every so often, to get the release
cloth and bag out, but they are easily closed later.

Good one.

Or just lay up one side, with the edges cut at a proper angle. Fabric
flow from the table, uphill, across the inside and downhill back to the
table. Peel-ply the hillsides. Once it cures, trim the excess fabric,
flox the 3 pieces together, and glass the outside.

The inside would look like this with * representing the fabric:

**********
*----------*
****/ \****
----------------

On Apr 8, 10:58 pm, Ernest Christley wrote:
Morgans wrote:
"dirigible designer" wrote in message

Now I just have to figger out how to get those layers of
fiberglass, (matt and cloth), on the inside of the hollow triangular
spar 8-]

Use the opposite of vacuum bagging; pressure bag it.

Make up glass cloth with epoxy squeegee into it, then lay it on the foam,
lay on the release cloth, make up the pressure bag, fold it all up, bind it
on the outside with tape or something, then put the pressure to the bag and
let it cure.

You will have to cut an inspection panel every so often, to get the release
cloth and bag out, but they are easily closed later.

Good one.

Or just lay up one side, with the edges cut at a proper angle. Fabric
flow from the table, uphill, across the inside and downhill back to the
table. Peel-ply the hillsides. Once it cures, trim the excess fabric,
flox the 3 pieces together, and glass the outside.

The inside would look like this with * representing the fabric:

**********
*----------*
****/ \****
----------------- Hide quoted text -

- Show quoted text -

That would work, but you still have the issue of making up a curved
spar from a bunch of flat panels. Lots of very careful angle-cutting
required. The beauty of composites is the ability to do smooth
curves. Why not a tubular spar? You could use a swimming "noodle" to
do a mockup or an R/C proof-of-concept ship.