Welcome to http://www.edge540.com

A sub web site of http://www.rcflier.com

This web site is hosted by Bob Hudson.

I am by no means a professional or "master" builder and these procedures may not be the best methods for you.

Carden provides a nice construction guideline and color photos as an aid to building their kits.

I have chosen to build things in a little bit different order than they lay out in their manual

Part 2 - The Motor Box

Steve and I have decided to go with  KS mufflers for an attempt at noise reduction. We have made a few modifications to the motor box assembly to accommodate these mufflers. The major mod is the installation of a sub floor to

The motor box is built primarily of 1/8" aircraft ply.  Very strong stuff.   Also heavy stuff.  Carden provides optional lightening holes shown on the side view plans.  We went with this suggestion and opened out these five large holes.

Since there will be a foam "quarter round" block glued up against the motor box side, and since we are mounting large KS muffler cans in the lower part of the motor box we decided to close up the bottom three holes with 1/8" balsa for some heat protection to the foam.

Also, in order to fit the KS mufflers we decided to install a sub floor in the motor box which essentially divides the motor box into an upper half and a lower half. Another view of the KS mufflers Yet another view of the KS mufflers

The first step in building the motor box is to epoxy the ½" square hardwood blocks (provided) to the front and bottom of the motor box sides. The firewall and the landing gear plate are in turn later epoxied against these blocks. I simply epoxied (and clamped) the blocks in place then used my "mini back saw" to trim the angles on the protruding bits. The sub floor of the motor box is made of 1/8" light ply (cross grain to the motor box) this is not included in the kit as it is a "builders option".

The support for the sub floor is 3/8" square balsa and is glued to the ply motor box (in) side in line with the lower fuse longeron. Lay the motor box side on the plans and draw the extension of the fuse longeron forward onto the motor box side. Glue the sub floor longerons to the inside of the motor box side.

  See the motor box side with the hardwood blocks and sub floor support

The motor box is attached to the fuse sides with formers F2, F3, and F4. These are 1/8" aircraft ply. They are butt glued against the motor box and the fuse side. Being a bit paranoid about butt joints I have decided to re-enforce the joint against the motor box with a 3/8" square balsa stick. I figured it would be easier to glue these sticks in place now than to fiddle with them while trying to glue the whole motor box assembly to the fuse. Layout the location of F2 and F3 on the motor box sides.

Cut 3/8" square stringers the same length as the formers and glue (I epoxied them) them onto the motor box wall. I used CA for this. Drill lightening holes in Formers F2, F3, and F4.

I also glued 3/8” balsa to the motor box sides 1/8” in from the rear edge of the motor box. The rear panel will now press up against these stringers. This performs two duties. It provides a better glue joint than just a “butt” joint between the sides and rear panel of the motor box. It also helps keep the rear plate in position while fiddling with the pieces over the plans. I used clamps through the lightening holes to clamp the rear plate in position

	Motor Box preparation See the ½” gear and firewall blocks, the 3/8” balsa longerons for the sub floor, and the 3/8” balsa stringers for the rear panel
	See F2, F3 and F4 lightening holes
	Another pic of the formers clamped in place
After the stringers are dried we epoxy  the formers against the stringers. This proved to be beneficial as the formers now act as feet to hold the motor box walls in place while gluing the motor box together over top of the plans. Place the motor box pieces over the plans and be sure of the alignment over the plans. I pinned small cut offs (about 2” or 3” long) of 3/8” square balsa over the plans to keep the sides, fire wall and rear of the motor box in place over the plans.
	See the motor box being assembled #1 rear view, notice the builders square to ensure a true assembly
	See the motor box being assembled #2
	See the firewall clamped in place
	See rear view again, the square is actually clamped to the box while the epoxy dries
	See Notice the big square clamped to the motor box to assure a true assembly. Also notice the (extra) large oval lightening hole (pic #5) we cut in the rear panel of the motor box.
	See Gluing the gear plate onto the bottom of the motor box
	See Another view of the gear plate clamped in place notice the wing tube in place checking side panel alignment
	Nice view of motor box showing F2, F3, F4 lightening holes and rear plate, and 1/8” lite ply sub floor see the small blocks pinned to the bench holding the assembly in place
	Front of motor box, see the fire drilled (note the offset) and the lower front plate opened up for exhaust headers again see the blocks around the motor box
	Front view of motor box showing mufflers in place (looks crooked but it’s just the camera angle
	A view of rear of motor box, see the mufflers and 1/64” ply rear plate
	A piece of 1/64" ply forms a nice radius in the rear of the motor box
	Rear of motor box with mufflers being trial fitted
	Rear view of 1/64" ply looking thru cutout in rear plate
	After the motor box is fabricated the fuse sides can be joined to the motor box.