Sig 1/3 Scale Spacewalker Review

Engine Mounting

9/9/2002 - All the engine mounting is completed.  As shown in the fuselage construction, I built an engine box to mount the engine.  I made the firewall by gluing two sheets of 3/32 plywood together to make a 3/8" (8-ply) firewall.  The engine box is made of 1/8" plywood.  I pinned the sides of the engine box to the firewall using bamboo skewers.  I have found that these are very tough and work well for this purpose.  I used 10x32 bolts with blind nuts to mount the engine to the firewall.  I had to deviate from the plans by recessing the bottom of the firewall to accommodate the J&A Engineering mufflers that fit behind the cylinder head.  This is another reason I went with an engine box - for additional strength (and yes, a little bit of weight, but I will need it to offset the servos in the tail).

I ended up using 1/4" round plywood spacers to get the correct engine placement relative to the cowl.  I used nyrod and ball-swivel connectors to connect the throttle linkage.  I made a muffler support using 3/32" x 3/8" flat steel.  I used steel because I have found that aluminum, while lighter tends to crack/break more easily and the mounting holes tend to wallow out.  I made a cable keeper (bracket) for the spark advance wire to keep it from vibrating/rubbing against the engine.  I also made a keeper for the fuel line from an old nose gear holder.  See pics for details.

Return to Top

Click on the thmbnails below view the full-size image.  Click your browser's BACK button when finished viewing the picture.

Picture	Comments
	9/9/2002 - The Brison 3.2 mounted and ready to run!
	9/9/2002 - This view shows the round plywood stand-offs that I made to get the correct spacing.  You can also see the fuel line and throttle linkage.
	9/9/2002 - This pic shows the keeper I made to hold the spark advance wire.  I used aluminum struts that I flattened then bent around a drill bit to hold the fuel line through which the wire runs.  I slit the fuel tubing so I could slip it around the wire, then slipped it through the keeper.  At final installation I will tighten the aluminum around the fuel line so it will be nice and snug.  I attached the keeper to the engine using the pre-tapped socket head bolt which was for a smoke system.  Notice that I replaced the smoke fitting on the muffler with a socket head screw since I won't be using a smoke system on this plane.
	9/9/2002 - A view from the bottom.  You can see the keeper that I made to hold the fuel line in place so it won't rub against the muffler.  You can also see the muffler brace.  The J&A Engineering muffler comes tapped for this type of brace.
	9/9/2002 - Another view.  You can see where I mounted the muffler brace to the engine mount.  Notice that I have not yet added foam padding around the holes in the firewall where the spark plug wire and spark advance wire pass through.  This will be done at final assembly after I have sealed the firewall with thinned epoxy.

Return to Top