Chapter 4: Fuse Bulkheads

September 18th, 2001

Foam pieces cut for the seat back and epoxied.

I have read a number of the messages from the Cozy Newsgroup Archives 
and have seen a lot of discussion on how to best cut the PVC foam (you 
can't hot-wire it!)  I don't really know what the fuss was all about; I just 
bought a razor knife (the kind layout artists use) from Menards for $0.97.  
It has a long retractable blade (2"), and made the cuts easily with only a 
couple of passes.

Because a single sheet of foam is not tall enough for the Seat-Back, you 
need to piece two sheets together.  I then 5-minute epoxied them together 
and weighted them down for a twist-free join.

October 15th, 2001

Okay...not much progress for the last three+ weeks; mostly due to various 
things going on around the Wilson house-hold.  I have managed to glass the 
forward side of the seatback and make the cutouts for the Upper Longeron 
and the Electrical Conduit.

I had to make the first 45-degree cut twice as I got the angle wrong and had 
to add a 1-inch strip to the bottom of the foam (in John Slade's immortal 
words..."No one will ever know.")

I started by marking the material to cut off and then proceeded to cut it with a 
hacksaw blade by hand (leaving some material so I could sand it to shape.)  
The problem showed up when I started to sand; it seems my cut wasn't 
particularly straight on the bottom side, and when I started to sand, I found 
several low spots.  I continued sanding (in an effort to get a straight edge at 
45-degrees) and by the time I finished, it wasn't at the right 45-degree angle 
and I had lost 0.2" off of the length.

Giving up on the "by hand" approach, I decided to build a cutting jig that I could use 
to make the cuts instead.  It took me about 40 minutes to build it, but it helped me 
do the rest of the cuts on the seat back in about 5 minutes.

Lesson Learned: When you need a jig, build a jig!

The tool consists of a Dremel Tool on a flexible shaft that is ty-wrapped to a 45-degree 
Fence/Jig.  I installed a spiral cut bit from Dremel...worked like a charm:

Left: The Electrical Conduit Cutout
Right: The Upper Longeron Cutout.

Problems Again...

After making the cuts above, I then started glassing the back (the Rear-Passenger 
side) of the Seatback.  Everything seemed to go great with the layup (although the 
temperature WAS falling), but after the cure, I discovered 5 large bubbles of about 
3/4" in diameter.  Rats!

Okay, this could technically pass the inspection, as the seatback is not subject to 
aerodynamic pressure, but I'm a perfectionist, so I've got to fix this or I will never be 
happy with it. 

December 28th, 2001

Being an engineer who wants to see how things go together before I commit to it, I decided 
to enter the Bulkhead Plans into a CAD package.  I also found a great deal on an E-Size 
plotter that can plot an entire full-size bulkhead on one sheet of paper.

I then cut the patterns out, traced them on foam, and cut the foam to shape with a razor knife.
N.B. Don't try to cut the foam all in one cut; instead make several shallow cuts.

January 21st, 2002

3-D CAD and Modifications

I have now finished the final positioning of the Cozy 3D CAD Bulkheads.  

I've plotted out F-22, F-28, the Seatback Cutouts, and the Instrument Panel.

My plan is to check the form and fit of the various pieces with my 3D CAD Package so that I 
can build a better understanding of how all the pieces will fit together.  Since I am considering 
a couple of modifications, I want to make sure that anything I do won't have un-for-seen 
ramifications.

The two modifications I am pondering at the moment are:

The Velocity Rudder Pedal installation seems straight forward enough (but I still want to 
check it in CAD first.), and I am unsure about the ramifications of enlarging the Leg-Holes 
in the Instrument Panel.  I am thinking about removing an inch from the outside (near the 
Elevator Push-rod hole) to allow a little more room for my thighs.  I've sat in a couple of 
Cozy's and have already discovered that I could use that extra inch.  (N.B. I also considered 
removing material from the center of the Instrument Panel, but this would not really provide 
any additional Leg-room since you still have the Nose-Wheel Wheel-Well to deal with.)

To be sure on this, I think I will need to consult Nat and the Cozy Builders mail list.  I'll post 
whatever I discover in case others are consider a similar modification.

Update:

It seems the best course of action at this point is to wait until the Fuselage Tub is assembled 
and trail fit it then (making any mods that seem reasonable then.)  A couple of builders have 
been able to gain an inch or more of leg-width (take a look at the archives if you have an 
interest.)  I'll be investigating this in more detail in later chapters.

January 26th, 2002

F-22 and F-28 Foam Cutting

David has decided he wants to help build the Cozy!  He'll come to me and say 'Build Cozy 
Pieces!"  And then he'll run into the garage (how can I refuse?)  Now if I can just get the girls 
doing layups!

I finished cutting out the Clark Foam per the plots (see above)...but I found out how brittle this 
stuff can be when cutting.  I accidentally bumped the edge of the foam against some foam 
scraps on the table and cracked it.  Easy to fix with epoxy, but I'm annoyed at being sloppy 
with my cutting.

F22 being 5-minute epoxied with the hinge-tape method (see archives.)  This worked fairly well.

January 28th, 2002

F-22 Layup

Another goof...I thought I might keep my micro-slurry warm by putting it in the Epoxy-Pump Hot-
Box in between Microing F22 and F28 (can you see what's coming?)  When I poured the micro 
on F28 it immediately solidified into an unworkable mess.  Apparently it exothermed from the 
heat in the hot-box. 

Another lesson learned: Once mixed, do not store epoxy or micro in the hot-box!

I had to sand (and sand and sand...) to remove the slurry.  It took me a long while, but I finally 
recovered the piece (I was using 80-grit to keep from gouging the foam.)

One side of F22 (with the Doubler in place), rolled and peel-plyed.  This picture was taken 
just before I weighed down the piece for cure.

March 23rd, 2002

Instrument Panel

I am finally back to building.  I have been working on my Private Pilot Certificate and I'm having 
to find the time for the Cozy whenever I can.  Today it was cutting out the Instrument Panel Foam.

This is the same foam as F-22 and it is even easier to accidentally crack (I did it twice!)  But 
fortunately, it is also easy to fix.

March 26th, 2002

I finally get a chance to do the layup on the Instrument-Panel, but I since I have to travel to Detroit, 
I miss the knife-trim stage.  Unfortunately, with all the interior holes on this piece, I spent a lot of 
time cutting them out with a Dremel and hacksaw later!

My advice, plan ahead on this piece and do the trimming at the Knife-trim stage!

April 6th and April 12th, 2002

I am still working on my Private-Pilot Certificate, so I've had to take some time off from the project
BUT, at least I can get a pretty picture or two while on my Long-Cross-Countries!

Also, April 12th was my birthday, so what kind of cake should my daughter bake for me?
(and if you can read Numerals in extreme parallax view, then you've just figured out that I'm 37.)

June 29th, 2002

I have finally received my Private Pilot Certificate!  Here I am getting congratulated by my Instructor, 
Abbie Friddell.

Now maybe I can get back to building..."What's that honey?  The kids want to go on Summer
Vacation?  Arrgghh!"

August 24th, 2002

Okay, the Beach Vacation is out of the way, Oshkosh is done...now I can finally get back to building!

I started by making the 22-layer hard-points for the landing gear bulkhead.  I have seen some postings
saying how hard it was to get 0.25" thick hard-points.  I didn't seem to have any problem.

First I marked the 8" x 12" box on some clear plastic and started the lay-up (layer by layer).  Once I had
it all wetted-out, I then used some 0.25" scrap foam around the lay-up and placed a large particle board
over the whole piece.  I then added about 80lbs of weight on the board.  When I checked later, I had a
an 8" x 12" x 0.25" hard-point.  (Okay, I didn't take a micrometer to it, but every ruler I had said it was
0.25"!)

I then cut out the four hard-points needed for the Landing-Gear Bulkhead.  I spent some time on the
Band-saw doing this (I can't imagine how much fun this would have been with only a jigsaw!)

After cutting, I then traced the hard-points onto the bulkhead foam, cut the foam away and epoxied
in the hard-points.

September 2nd, 2002

I started my overall lay-ups on the Landing-gear Bulkheads...BUT

I haven't really messed up in a significant way for a while, so I guess I was overdue.

I discovered I forgot the UNI plys...opps.  Okay, this is easily fixed.  I just needed to roughen
the area for the Uni-plys and add them...no big deal, but I started wondering if I have missed
any OTHER plys?

After a thorough check of all the drawings and plans, I find I haven't missed any other Plys (YET!)

September 22nd, 2002

Since I have been very busy lately building a number of GPS Demos for Convergence-2002 
(an Automotive Electronics Trade-Show that occurs every other year in Detroit), I'm
having to fit my epoxy-habit in where I can.  I figure now is a good time to do some small stuff,
like the Instrument Panel Stiffeners.

I have decided to bring the stiffeners to the edge of the leg openings to give a less-harsh edge
to the openings.  I have done the top and the inside edge of the leg openings, and later (after
I verify that I'm not affecting any later Chapters, I'll extend the lip to the bottom and outside edge
leg openings.

I have tried it on for fit, and so far I LIKE IT!

November 29th, 2002

Back to building with a vengeance! I want to finish Chapter 4 in the next week (and I'm on
target to do so!)

After reading all the stories about the Blind-Screws that are called out in the plans later
turning and having to be repaired, I decided to go with the Archives Music-Wire method.
To do this requires using a Dremel to slot the Screws to the width of short pieces of cut-off
music wire that is later epoxied into slots on the Firewall pieces.

After slotting all the screws, I then needed to route the slots (about 1/32nd of an inch deep)
in the firewall pieces.  To accomplish this, I used a round routing base for my Dremel and
clamped a straight-edge to the piece to guide my cuts.  This produce very nice and straight
edges.

After inserting all the screws, I then epoxied the screws and music wires in-place, and trim
after cure.

December 4th, 2002

Chapter 4 is FINALLY DONE!  At this rate, I may be one of those ten or 15 year builders!

Actually, I have had a lot of time taken up in the last year and a half due to finishing up my
Private-Pilot License, building three new rooms in our basement, and coordinating several
household moves of family members and friends.  I'm hoping the near future may be a little
more quiet so that I can concentrate on more building activity (but now its winter...guess I'll
be using the Garage heater quite a bit!)