I have also thought long and hard about doing this.  The main downside
seems to be the possibility of having a (another) combustion-supporting
part in the engine compartment.  Of course, the cowling is glass in a

lot

of our planes, anyway.  High-temp and fire-resistant epoxies are

available.

There are some design issues, such as which lower intake flange/manifold

to

use?  A cut-down stock lower manifold?  Paul's flange and lower tubes?
Neither seem exactly ideal for a free-flowing composite upper manifold,

but

Paul's parts offer more flexibility.

One could bond in a G-10 phenolic plate (handles 300 degrees F)to make a
nice flange to bolt onto the lower aluminum manifold if a slip-fit +

clamps

was not desirable.  I personally prefer a bolt-on fit instead of

crushing

the CF tubes with hose clamps.

Using PVC or foam tubing-over-copper, one could make a plug out of some
nicely contoured pipes in 3 dimensions without too much problem. This

would

obviate some of the issues when using straight pipes and standard

curves.

These could flow smoothly across the engine into bellmouths and a
throttle-body box, which would require a separate molded piece. At this
point, one could include the counter-pulse augmentation by pointing the
opposite tubes at each other, if desired (as per Tracy's original
recommendations).  This may no longer be ideal (Paul?).

A top and bottom, two-piece mold could handle the majority of this

design,

and include flat areas between the tubes for bonding at assembly time.

This

area could also serve as a location for additional supports/mounts.

Bonding

in the injector bosses shouldn't be a big deal (could also use G-10
phenolic).

To make this worthwhile, it would need to be standard enough to be

usable

by many builders.  I would be happy to participate in this project, but

not

for profit.  Once the mold were finished, it would be pretty easy to pop
out manifolds at a minimal cost.  Perhaps the molds might even be shared
among the group so people could make their own manifolds.

Scott Gettings

Instead of expensive hard female and male tooling if you take a bent
aluminum tube and slice
it in half using a slitting saw in a mill. That would give you a mold for

a

wax
male plug.

Paul Lamar

"Decker, Michael" wrote:

Another option would be to use polystyrene foam as a core.  If epoxy is

used

as the matrix for the carbon, you could then melt the foam out with
gasoline.

Mike

That works fine but it is labor intensive as each foam core must be shaped
by hand.

If you have a female wax mold on the other hand you merely melt the wax and
pour
it in. You then have a disposal mandrel in a few seconds.

Paul Lamar

Interesting discussion.  I would definitely prefer to invest the time and
effort into a good plug with all the needed curves and shapes.  Then the
mold is easy to pull off of a good plug, and would be perfect for many
product runs.  Another mold can always be created if needed. Using metal
tubing would make the complex shapes of the plug much more difficult to
construct.

A throw-away plug could even be sculpted out of wax.  This would make the
flat sections and bonding flanges between the tubes very easy to create.
With one side of the mold made, you'd flip it over and sculpt the wax on
the other side.

A carbon fiber layup in each side of the mold independently would obviate
needing a core.  The two sides (half tubes) would simply be bonded together
after they set up, and add the flanges, throttle body box, etc.  Heat cure
the whole thing.  I estimate about 2 lbs. total weight.

Scott Gettings

I need to get my NC mill working so I can make 3D molds. I am thinking of 
hiring a C programer to get it up and running with this stuff.

http://www.servotogo.com/

http://www.linuxcnc.org/


Paul Lamar
 
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