N451BX

Homepage/Builder's log for Cozy MKIV S/N: 1671

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    - Epoxy Box
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Ch 3 - Practice
Ch 4 - Fuse Bulkheads
Ch 5 - Fuse Sides
Ch 6 - Fuse Assy
Ch 7 - Fuse Exterior
Ch 8 - Headrests, Heat duct
Ch 9 - Main Landing Gear
Ch 10 - Canard
Ch 11 - Elevator
Ch 12 - Canard Install
Ch 13 - Nose Gear
Ch 14 - Centersection Spar
Ch 15 - Firewall
Ch 16 - Control System
Ch 17 - Trim
Ch 18 - Canopy
Ch 19 - Wings, Ailerons
Ch 20 - Winglets, Rudders
Ch 21 - Strakes, Fuel, Bags
Ch 22 - Electrical
Ch 23 - Engine
Ch 24 - Covers, Fairings
Ch 25 - Finishing
Ch 26 - Upholstery
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SHOP


Chapter hours:  TOO MANY                                      Total Hours:    0





Cozy MKIV aircraft have been constructed in every imaginable space, from studio apartments to fully equipped aircraft hangars.  Many are built in garages.  Some are built utilizing state of the art CNC tools or laser cutters, others with simple hand tools.  I decided to go for a balance of practicality in both the aircraft, and the methods used to build it.  For each builder, some attributes of the build are more important than others.  For me, the shop in which the aircraft is constructed was vitaly important, following the notion that the finished product will be representative of where it came from, or rather, a solid foundation is a cornerstone of a precision build.

My "shop" is an attached two-car garage.  As some others have stated, having the build as close to home as possible will make it easier to stay engaged versus starting it at the airport, or other location away from home.  The garage has enough space to build all components of the Cozy, and also to attach one wing to the fuselage at a time for pre-assembly and fitting before moving to the airport for final assembly.  In short, I will be able to assemble all parts of the airplane, minus one wing at a time, so I can hopefully shorten the amount of final assembly time at the airport before flight testing begins by having already assembled everything at least once.  This is the current plan, but will be subject to change as we proceed.





Tables:  Go on a forum, or EAA meeting and ask what kind of table(s) you should have for building airplanes with.  You will get nearly as many answers as there are people.  Which is right?  The correct answer is whatever works best for ytables4ou.  Some prefer the "EAA tables", others prefer to build a table worthy of supporting a house with engineered beams, and yet others simply bolt some sturdy framing lumber together and say "get on with the build already". 

The Cozy MKIV plans call for a solid 11'X3' torsion-box design table.  I dithered over this for awhile, and finally decided on my own creation - three (3) separate 36"x48" torsion box tables that can be leveled and bolted together to form a 3'x12' table for fuselage and wing construction when needed.  Otherwise, the separate tables can be easily moved and used independently.

The "torsion box" construction is simply a framework sandwiched between two skins.  The principle of it is to carry more load while using lighter and fewer materials. Having a "skin" (plywood sheet) on the bottom as well as the top surface helps to stiffen the structure, and resist warping by counteracting any forces from the top surface.  This is also supposed to help keep it flat and level. 
tables2
I used 1/4" sanded plywood for the bottom, and 3/4" sanded plywood for the top.  The "joists" and sides of the box are 1"x10" white pine.  The legs and leg crossbeams are regular framing lumber, 2"x6" and 2"x4", respectively.  I bolted the legs directly to the torsion box before securing the top.  The top and bottom skins are glued and screwed to the 1x10s.  Everything is glued, and I learned on the first table that you must have the 1x10 frame perfectly square before you let it cure. 

First off, I am no woodworker.  I will own that.  Metal has always been my medium of choice, and can do quite well if something needs to be welded or machined, but I have never fully appreciated the skill of woodworking until these tables.  I glued and screwed the first frame together with no fixture or jigging, leaving it to dry overnight with the "assumption" that I could manipulate it a little as needed to fit up to the plywood, which was perfectly square.  I learned the next day that wood glue has a cured strength of several thousand pounds per square inch, and does not take well to being manipulated.  In the ensuing battle to get the frame square, which ultimately involved a crude fixture and several nylon cargo ratchet straps, a couple glue joints failed.  While the joints did not physically come apart due to them also being screwed together, the "bang" they made just from the glue failing was pretty impressive, and made me glad they were also screwed, lest the whole thing might have come apart violently.  On subsequent tables, I squared the frame up with a carpenter's square as it was being built, and rigidly jigged it down to dry. 

The table top on the "short" 36" ends are flush with the frame.  This is to facilitate rigidly joining the tables together when a larger table is needed.  On the "long" 48" sides, the top overlaps the frame by 2" to facilitate clamping fixtures and workpieces to the table.  A couple coats of polyurethane on the top of each table and the edges should help protect the plywood from splintering, and facilitate easier removal of epoxy (maybe).
tables8
As shown, they are not equipped with the leveling feet or the holes for joining them together.  Still deciding on exactly how I want to do that, but leveling and joining is not needed right away, so moving on. 
 
Total time working on tables: approx. 72 hours.  I took a lot of time on these.  Wanted them to be useful long beyond this build. 





Drafting Table:  This was not in the plans, nor have I seen it in anyone else's plans yet, but it fits in with my approach of keeping everything neat and organized.  I built a "drafting table" for tracing templates on, keeping a drawing out but away from epoxy while building, and also for storing drawings.  It's tall enough to work with while standing up, and the hinged lid allows all of my manuals and drawings to stay clean while dust and epoxy are flying through the air. 
drafttable1drafttable2drafttable3
Total time working on drafting table:  approx. 22 hours. 





Cutting box: I learned quickly that trying to handle 40" rolls of fiberglass, roll it over a wet part, then hold it and cut it is an exercise in futility.  It results in fiberglass strands running in all directions, lots of spilled epoxy, and cuss words scattered all over the shop.  The best way to handle fiberglass cloth is like any other.  Have a large table to cut it on, then roll up the individual pieces and unroll them on the piece you are working with.  Much better. 

My cutting box is mounted to the wall, has metal rods (3/4" rigid conduit) to hold the rolls, and a folding door with folding legs that is like a double-jointed murphy bed.

cuttingtableopen

The rods pull out of the ends to replace rolls as they are used.  I made room for four rods, to have two rolls of each fiberglass at a time, but so far have only been using three, and just leaving extra rolls sealed up in plastic on the shelf.

cuttingboxclosed
When it is closed up, the door, table and legs all fold up to less than 12" from the wall, keeping the shop open. Four pull latches hold the door tight to the cabinet to keep dust  out.  I considered a temperature control for moisture, but we live in South Texas, so moisture has not been much of an issue.

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