|The Motor Box is complete through
the Cleco stage with some riveting. It has taken nearly one
month. That month of work also includes "overhead" work such as
reorganizing the work area, improving the fuselage stand, finding
misplaced parts and tools and reviewing images of other projects on the
internet. Work remaining: final trimming of parts, reaming holes
to #30, cutting and flanging holes in Bulkhead "A" (or nosebowl).
Internal baffle hasn't been made yet.
| Early stage for my motor box:
Factory Image for the Motor Box Parts:
My annotations ...
|Cowl Skin brace: either 1/8-inch or .040 aluminum
||Upper Cowl Piece
||Bulkhead "A: or nosebowl with Upper Cowl Piece
||Engine Support Angles ... note: there is a temporary brace at the front to hold the angles 11-inches apart
Wood spacer or pivot point will be replaced ... see below
Upside-down ... Charles Snyder
|The Bottom Cowl Baffle was very
baffling to me. Finally, I determined that the Mylars from the
factory were different from the factory drawings. FURTHER, nearly
everyone seems to have gone their own path.
Very nice execution by Charles Snyder. His blog shows 230 hours for the engine compartment.
Charles SnyderHere, the baffle appears to be flush ... but the angle is deceiving
Beautiful job on the motor box:
... anyone for tennis?
|Step 1: Accurately
install the Firewall Support Angles (3/4 x3/4-inch angles).
Ensure that the angles are level, parallel, perpendicular to the vert
stab, and 6-inches apart, bottom to bottom (angle opening faces upward).
I cut the two Firewall Support Angles from "scrap" angle. This angle was originally to be a wing spar cap ... but I drilled a mirror image (GOOF). Thus, the angle was already drilled at the 1-inch spacing as called out on the drawings for the Firewall Support Angles.
Material: 3/4 x 3/4 x 1/16th 2024T3 ... 17.75 inches long and 17.625 inches long.
GOOF! ... You will note that the A-B skin was trimmed flush with the A bulkhead at the lowest portion to allow the fuselage to pivot on the fuselage stand. Plans call for a 5/8-inch extension of the A-B skin past the bulk head. The doubler will fill this spot.
|As I added parts to the Motor
Box, the nose started getting heavy from all the Clecos. That
resulted in flexing of the Bulkhead "B". A new pivot stand
attachment was fabricated.
This version used 1/8x1/8x1-inch angle and scrap 3/8-inch plate from the center wing carry-thru.
The Firewall Support Angles now carry the weight of the nose without any flexing. Also, the support plate is further from the firewall allowing more of a pivot before contacting the Bottom Cowl Braces (which I have left off to allow more pivot).
This image is out of chronological order.
|Cross support angle in addition to being riveted with Type 1 rivets is bolted to the side rail angle using two AN3-5A bolts.
Side rail awaits final trim flush with cross support angle.
Side rail will be trimmed flush with cross support angle.
|Install the engine support 1x1-inch angles to the lower cross brace
angle ... centered and 11-inches apart on the inside, 13-inches outside.d
In this image, I show a 1/8-inch bar stock holding alignment near the front of the engine support angles.
|The bar stock brace thickness interferes with installing the Horizontal Component; thus ...
- Use an angle made from .016 aluminum with ends that lie flush on top (drill holes in the engine support angles about 1.5 inches from the front)
- Use an temporary rivet to hold the angle in place ... a Cleco will get in the way.
|Install the Motor Vertical Component to the Engine Support Angle ...
make certain it contacts the Lower Bulkhead Doubler and is plumb
A spacer is temporary installed to represent the space that will be taken by the Motorbox Horizontal Component.
|Drilling corner hole through Vert Comp and Engine Support Angle.
|Attach the Motor Horizontal Component flush with the Bulkhead Doubler
and the front outside edge of the flange is flush with the outside edge
of the Engine Support Angle.
Motorbox Horizontal Component held in place with cleco. Square up the Motorbox and drill holes into Bulkhead A Doubler and into the Engine Support Angle about 1.5 inches from the end (or what ever you like).
The circular Sharpie lines on the Vertical Component were the lightening holes for the wing spar. The wing sparweb developed a kink due to an accident ... but most of the sparweb was usable. I could get out the alcohol and remove the Sharpie lines :-)
|Cut and bend two lower cowl braces (.040 aluminum)
GOTCHA: Note that the mylar drawing shows the part to be 1/4-inch wider ... I added another 1/8-inch ... and wish I had added 1/4-inch for a total of one-half inch! (GOOF)
(The orange line is the size on the plans, Page 2, location E4)
Bend the 90-degree flange before drilling any holes!
|To effectively use the
shoe-shine method of bending the heavy .040 aluminum, I cut a rectangle
of aluminum big enough to build two Lower Cowl Braces; plus, and extra
two inches. This length is required since the shoe-shine method
will not work with a narrow piece of metal. A block of wood
clamped to one end helped bending at the edge.
|Bending the 90-degree flange was straight forward using only Avery fluting pliers (see quid.us/hummel/tools). Gradually crimp and bend while pushing down against the table.
|Install the two lower Cowl Braces while making certain the motor support angles are perpendicular to the firewall and parallel
You can see why I would have added another 1/8th inch. Alternatively, better positioning would have solved the problem ... BUT, I back-drilled the two bulkhead holes before making the 90-degree bend. That left narrow margins for the first hole between the brace on the flange on the Vertical Component. GOOF!
|Test fitting mylar.
I marked on the mylar along edges that should be extended one-quarter to on-half inch to be later cut down for an exact fit.
|Test fitting rough-cut right Bottom Cowl Skin. Inside and outside views; plus side view before trimming to size
Nose Piece: Instead of building a form block over which to form the
Nose Piece ... I merely used fluting pliers to form the curved flange
... crimping while bending ... pressing hard against the workbench.
used a brake to form the other flange. The narrow tip gets slight
deformed during the bend, but nose pliers easily straighten the flange.
|Trial fit of the Motor Box nose piece.
Note: the piece is not pushed flush with the Bottom Cowl Skin.
|Installing Bulkhead "A". Checking for square to the Motor Support.
|Used vice to hold bucking bar:
||Nose Bowl and Lower Cowl Skin Doubler:
(I choose 2-inch wide .040 in place of 1/8-inch bar stock)
|Motorbox Bottom Cowl Baffle:
||Small bent tab on exit borrowed from Charles Snyder:
|Motorbox Bottom Cowl Baffle:
||Motorbox Bottom Cowl Baffle - inside view: