|
|
 |
Here are the sides, guarded by my son James, ready for the 2 layers of BID.
I must admit, this was an intimidating layup and the sides (covered with plastic I
must add) sat for a while while I waited for my friend Jeff to come over and help me do
it. You can see wax paper and other stuff assembled around the edges of the forms to
keep the mess down when the layup actually begins. While many of you probably just
let the epoxy just drip on the floor, I try to keep the mess down as much as I can.
This keeps me from getting aggravated about the mess and the layup goes more smoothly! |
 |
My fried Jeff was in town around the time I did this layup. I talked him
into helping me one day while he was visiting. Thanks, Jeff, for the help with this
layup - it's definitely a two person layup. I lost count of how many cups of eopxy
we mixed. Jeff's reward was simple - he got to play with Emily for a couple hours. |
 |
Here's the layup, many hours later, after we were done. We did this in
two pieces (and this was a bad idea - next time I'll follow the plans!) and thus had to
put some wax paper and weight in the center along the longerons to keep things flat and
eliminate lifting. The hardest part of this layup is the fuel gauge and the flight
control depressions. You could actually use a third person to do this, they could
mix epoxy while the first two each do one side of the layup. It's done now, though,
and turned out pretty well. Next time I do a really large layup I think I'll work
with a crew of four or five... |
 |
When I did the 4-layer UNI layup on the fuselage longerons, I had major bubble
troubles. You can see some of the bubbles in this picture. They formed all
along the layup, primarily at the corner, but also at the holes where the nails were when
the longerons were laid up. I didn't round over the corners of the longerons,
because (begging Nat's pardon) it didn't say so in the plans. After I e-mailed the
Cozy builder's list, I was reminded that that was in the plans, in chapter 3. I
think my interpretation of this was two-fold, first, this was the first time you were
supposed to round off and were not told to - thus I assumed you were not supposed to
because it wasn't mentioned. Second, I made the assumption you were not told to, and
not supposed to, because of the loss of strength in the longeron because of the reduced
cross section. Well, let's just say it was painfully obvious you were supposed to. |
 |
Another image, showing more bubbles. You can also see from this picture I
did the layup in two sections, one side at a time. If you do this right the first
time, do it in one layup as it will help the UNI lay down on the top better. As it
turns out, I did mine over, so, it was better to do it separate as then I had less to
redo. |
 |
Most people I told about the bubbles told me just to fill them with epoxy.
You do this by drilling an in and out hole, then injecting epoxy with a syringe (no
needle, just a fine point) that Wicks sells. I pondered and stressed over this idea
for a while. I came to the conclusion that I didn't want to leave it that way, holes
filled or not. So, I bought a heat gun and, working slowly and using pliers to pull,
delaminated all 4 layers of UNI back off of the spar. I then rounded the corners and
did the layup over. |
 |
The other place I had bubbles on that layup was where the nail holes remained
from when the longerons were laid up. I epoxied toothpicks into the holes (no,
they're not aircraft quality spruce, but otherwise there's just a hole so who cares) and
then sawed/sanded the ends off smooth with the longeron. This prevented air from
getting under the layup as I squeegeed and eliminated that bubble problem. You
probably could just fill them with epoxy but I thought this was quicker and lighter
overall. |
 |
My second attempt, as well as the second longeron, layups worked great. I
had the corners rounded, holes filled, plus a ton of experience and extra work preventing
me from messing up again. If I build another Cozy, I'll do this in one piece and
re-read the practice chapter more often. |
| Click
here for Installation of Longerons |
|
