A Cozy Start

In July of 2010 we adopted a nine-month-old Cozy Mark IV. When I say "nine-month-old" I mean there was approximately nine months worth of work put into the airplane. We inherited a solid start on the fuselage, nearly complete landing gear, a started canard, and lots of hardware and materials.

After sorting and accessing everything, Ced busily familiarized himself with the next steps in the plans and began ordering parts.

I busily planned a new site that would be dedicated to documenting the project. It would be sorted by chapter and have both aviation enthusiast speak and novice talk  (so everyone could enjoy the documentation). Then I busily did something else. And after that I busily tackled some other project. And so on and so on.

The fact that I would never make time to sit down and whip up a dedicated Cozy site became apparent, so I'm now adding Cozy build documentation to this site. I think it adds some flavor to the mix, don't you?

Because I've put off sharing Cozy stuff for so long, I'm skipping ahead to the most recent work since it's the freshest in my memory.

Enter the Nose Gear Box.

In simple terms, the Nose Gear Box is a container structure where the nose gear and its controls are housed. The construction of the NGB consists mostly of glassed PVC foam, or divinycell, and later, glassed 2 pound per cubic foot (pcf) urethane foam. Over the Christmas holidays we began work on laying up the two large panels of divinycell, called the NG-30s.

Ced utilized his CNC machine to transfer the NG-30 templates onto divinycell.

Following instructions, we covered what would become the attachment point (MKNG-6) of the nose gear strut with peel ply (fabric that easily releases from an epoxied surface and leaves a prepped area for bonding when removed). . .

 and covered the larger arched area with two plies of bidirectional fiberglass (BID).

The NG-30s were flipped and coated with a mixture of microballoons (tiny hollow spheres of glass) and resin (this mixture is also called "slurry") to help save on weight and fill pores in the divinycell in order to get a good bond between the foam and upcoming plies of glass.

(Side note: If we were to wipe the surface of the divinycell with pure resin in order to fill the pores and prep the surface for glassing, the weight of the part and, inevitably the airplane, would be too high for an efficient aircraft.)

Four BID later, the part was allowed to cure. Once cured, Ced trimmed them to shape and squared them up.

The NG-30s were laid out once again and Ced dug out the foam where hardware will attach (those three circles). These were filled with a mixture of resin and flocked cotton fiber (this mixture is called flox) in order to create structural hard points for hardware.
 

Ced whipped up a set of beveled 3" x 3.5" x 1/4" birch plywood with 1" x 1" x 1/4" aluminum insert doublers and a set of beveled 2" x 2.5" aluminum doublers to bond to this area (shown stacked below).

First, just the birch with 1" x 1" aluminum inserts were bonded to the MKNG-6 area with flox and four layers of BID were placed over the entire surface.

The aluminum doublers were floxed in place on top of the birch doublers and covered with two smaller pieces of BID.

Once this cured, the excess glass was trimmed and the NG-30s were clamped together to align the drill holes in all the hard points. 

The panels were then flipped and the glass was trimmed away from the MKNG-6 pivot hole area and all the foam was removed to expose the peel ply and glass layer just underneath the birch doublers.

 The area was then beveled.

The peel ply on top of the birch (the first piece of material that was laid down when the NG-30s were begun) was removed to expose a prepped glass area ready for bonding. Two plies of BID were laid down to finish up the MKNG-6s.

Once cured, Ced bolted the two panels together. . .

And fit the nose gear retract unit (Ced opted for the automated unit instead of the manually cranked design.)

Nose gear strut placed to get an idea of how the assembly looks.

With everything fitting properly, it was time to bond the box onto the F-0 (the oval panel that the box is sitting on in the below image). This panel was cut from divinycell and glassed with one ply of BID.

Ced aligned the box on the F-0 and floxed into placed.

 

Flox was used to make fillets at the bond lines and covered with peel ply. We opted to hold off on applying glass tapes over the fillets until the flox set.

Filleting the interior was tricky!

This assembly was allowed to cure while the bulkhead F-5 was trimmed (the squarish divinycell piece below).

The peel ply was removed from the fillets and two BID tapes were placed over each fillet.

The F-5 panel was also bonded into place with flox. . .

 
And covered with two plies of BID.

With the whole assembly complete, Ced aligned the box to the front of the fuselage.

And bonded it in place on the F-22 bulkhead.

The excess flox was wiped off and the bond was allowed to cure. We later applied tapes to both the external and internal bond lines.

And that's the first step to the Nose Gear Box! Whew!

(Quick summary: Using foam, fabric, and resin, we created the internal structure of the nose that houses the mechanical parts that swing the nose gear up and down. This structure was then bonded onto the front of the fuselage.)