Joining the two half cowls:
I took a simple method for accomplishing this. I put some tape on
the edge of the top cowl (for about three inches) so that the fiberglass
lay-ups on the bottom cowl won't stick to the top cowl. I then
sanded the edge of the bottom cowl and prepared a layup of five pies of
fiberglass material with epoxy. I used the pre-preg method where the
material is layed up on a plastic sheet. Then a second sheet is put
on top of the wetted lay-ups and a squeegee is used to take out the extra
epoxy. Then cut to size as needed, remove the top plastic sheet, put
in place and remove the other plastic. Very neat method and very
clean compared to what I've done when I made the cowling.
To hold the two half cowls together, I clecoed pieces of aluminum on
the outside of the cowling. I'll repair the holes later. I
will also need to build a stiffener because the straight portion of the
cowling is two flexible and it's hard to grab the inside lip with a
fastener (now a cleco).
The two eyes...
Ah... this is tough. I don't know if I'm just being too tired of
that cowling, but it seems I can't find an easy solution (this is written
on June 19, 2003). Initially, I tried cutting pieces of blue
Styrofoam to the shape of the cowl to make the form, but I could not
easily achieve the desired shape. I also determined that it would be
hard to lay up the cloth from inside around the rear portion of the
Next, I tried to make a form using a tube going through the
opening. Since the hole is not standard (can't just use a bottle or
existing container), I tried making one using the plastic from a container
I had. That did'nt work well because the plastic was too stiff to
take the proper form. .016" aluminum showed a similar
problem. I then spent about one hour in a Reno-Depot store looking
for a solution and over another hour at Wallmart. I found a plastic
material used for some kind of art that was flexible enough. I tried
with that and could not come up with a nice shape (the shape appeared distorted
and the material was too soft).
So, I decided to try another approach. Put spray foam and shape
the opening from outside. I used six cans of that spray foam and I created
a total mess. See below. The problem is that while the foam
expands, the core of the balloon is deprived from oxygen and does not
expand and dry. So, the core is mostly empty and there is an ugly syrup
remaining in there. Nothing can be done with this. So, I spent
a few hours to remove all the foam.
I then tried another approach which would require lay-ups from
outside. I glued a piece of 1/2" round foam all around the
holes and then applied a mix of epoxy glue and cotton fibers (flox) to
shape the curvature of the flange. Next day (it takes 12 hours to
cure), I applied another coat of epoxy, but this time, I used micro
balloon. Whlie it was curing, I determined that it would be
too hard to achieve a perfect shape, it's getting heavy and it takes too
long. So, I took a grinder and a sander and removed the epoxy and
foam. I had to repair a section of the fiberglass what was touched
with the grinder.
That's where I am... if you have any better idea on how to make these
openings, please let me know (firstname.lastname@example.org).
July 16th update: AH I got
I decided to take a few weeks off that cowling work and assembled the
canopy. I got several advises on how to do it and when I came back
to it, it went very well. Pictures below are self-explanatory.
(OH... sorry for the big files... I have a new camera and it was set in a
fairly hi-res mode).