Sunday, January 6, 2013

Ch 7: Gear Area & Rear NACA Scoop Prep

There are 4 birch pieces that get cut and then installed in the aft section.

Parts A & B are simple triangular pieces that provide a solid backing for exterior foam.  Note that the craft sticks were great to hold the pieces straight up while the flox cured.

Parts C & D are polygons that form bracing between the firewall and aft landing gear bulkhead.  I had to adjust the dimensions for parts C & D a bit to fit properly between the FW and LG bulkhead.  It's not real clear in the plans but the firewall drawing shows part D to be installed horizontally.  When I did that, I ended up with a small gap where the vertical and horizontal pieces come together.  Other builders have had this same issue and it is noted in the I filled the gap and moved on.  

Backside of Parts A & B (left) and C (right) while curing

Front side of A, B, & C showing the space where foam fills in.
Also, you can  see the NACA scoop to the left
before it was sanded to final shape.

Parts C (vertical) & D (horizontal) installed
w/ flox  filling the gap between.  The open
space gets filled  w/foam and shaped
 to match the bulkhead/firewall.

Closing out the scoop:
Next the foam for each of these areas was installed along with the PVC foam lining around the aft portion of the NACA scoop where it leads into the cowling.  This was then sanded down to match the outline of the firewall and aft landing gear bulkhead.

Rear bulkhead area completed and ready for glassing.
Between the bulkheads is where the landing gear will be installed.
An access panel will be formed to cover the gap in Chp 9.

To Joggle or Not to Joggle?
The plans call for cutting a 1/8th inch joggle into the edge of the NACA scoop at each of the landing gear bulkheads and the installation of some threaded aluminum slugs.  In fact, the bottom is installed with this joggle already in mind.  This is to allow for the future installation of the landing gear cover.  Getting glass to lay down properly on these joggles is notoriously difficult.  I decided NOT fact I filled in the gap formed on the installation of the bottom with a sliver of PVC foam.  I plan to follow Wayne Hicks landing gear access door plan as it's easier and looks to be a better fitting part when complete.  

Onward, cab

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