The Continental Engine

Drawing for continental.pdf

If you are into 3D printing I would like to share a link i came across.  I have not tried it but for a small price you can download the files to print the engine along with breather, and eyebrows.  piper-cub-1-4-scale-dummy-engine

Now on line a zip file contains 22 jpeg photos of the full-scale engine
fullscaleCubeng.zip

The Continental engine that comes in most kits looks ok at the 20-foot standoff rule, but some people look for a little more detail in an engine. Dynamic Balsa & Hobby Supply (link on products used page) makes a very nice vacuumed formed kit. It looks great, and is greatly detailed for being vacuumed formed. For some we need more details like nuts, bolts, screws, plug wires and more. No one that I know of makes such a kit, so it is back to the drawing board I  asked a friend that worked on full-scale aircraft if he could find me a few three views of the Continental engine. He brings me about 25 pages of info including some small three views. Being an AutoCAD drafter I pulled them in and drew a set of plans for the engine.  Because of the drawings I had to use they are not perfect, but close enough to work. It is so close that the average person could not tell.  Some parts below are pressed formed from plastic. See article on the web site about press forming.

Making the cylinders
Fins are cut from 1/32 ply. Spacers between fins are 1/16 Balsa unless noted on drawing. Through each section are two alignment holes to aid in stacking and gluing. Each section on the drawing contains a number; this is to help with assembly order. You will need to make 6 of number 1 for each cylinder. For number 1A through 1G and 2 through 18 you will only need 1 for each cylinder. On part 17, cut to outside outline and then shape the part to the inside line. On the top of the drawing you will see 1Athrough1G, only difference between each one is the two holes at the bottom. The holes are for the rod sleeves to go in. (TIP before cutting parts 2 through 18 out I stacked up materiel to cut four parts at one time.)

After all parts are cut out sand the edges of the ply fins to remove any rough edges. (TIP using a large cutoff wheel in a motor tool shape the edges of the fin’s. Most fins start out thick and get thinner as they come out.)Paint all edges of spacers and outer edges of fins. The Cub engine I modeled was flat black. I used apple barrel (craft paint) flat black paint. Paint all parts lightly and sand with 600-sandpaper after they dry and re paint if needed.

Now take a scrap of hard wood like a 1 by1 pine strip. Drill the two alignment holes in the board (use fin1A as a guide) to accept two hard wood dowels. Cut dowels about 3inches long. Do not glue them in the board. Now stack the cylinder by starting with 1A, 1, 1B, 1, 1C, 1, 1D, 1, 1E, 1, 1F, 1, 1G, and 2, through 18. Glue each section (I used thick CA) as you install it in the stack.

Mounting the cylinders
I used a strip of 1/16 ply 3/4 inch wide and a little over 4 inches long to mount the cylinders to. Paint strip flat black. Mount cylinders to center of strip using profile view on drawing to obtain spacing between cylinders. I drilledtwo1/16 holes all away through each cylinder and safety wire them to the mount, so if glue comes loose you will still have the engine held together.

Rod Covers
These are made from old section of outer Golden Rod. Sand the plastic with fine sandpaper and then paint flat black. Cut to length and insert into holes on part 17 and 18 allowing them to lie in the grooves in parts 1A through 1G. Do not glue at this time.

Intake.
I used hard wood dowels for the intake tubes. Sand the dowel with 600 paper. Now cut sections of dowel per drawing. Glue sections together and round corners of elbows. When finished, glue mounting plate on and paint them flat black.

Exhaust system.
The real pipes are several sections welded together. For part of the pip I used a 3/8 diameter hollow plastic pip that I located in the train section of my hobby store. Cut at a 45 deg angle the pip can be glued together to form a 90 deg elbow. Sand the outside of the pipe will make a nice rounded elbow. This is used on the end where the pipe turns and enters the cowl. The main section of the pip as shown on the drawing is pressed formed and is made as 2 halves that are glued together on the pip. You can make the mold from hardwood dowel, and Balsa. Using 5-mint epoxy you can simulate welding joints on the pipes by applying a small bead of it to the joints. When finished glue mounting plate on and paint them silver.

Attaching exhaust and intake system
Remove the Rod Covers. Micro Fasteners make some hex head bolts in small sizes they are great to simulate the bolts holding the exhaust and intake system on. First glue the exhaust and intake system on. Then take a small drill and drill the holes for the mounting bolts go in. Put a drop of glue in the hole and insert the bolt into the hole. When finished, reinstall the rod covers and glue.

Valve covers
The valve covers are not perfect scale, but close enough. They are pressed formed from plastic. Make molds from drawings out of balsa. Trim covers to fit part 18 and paint flat black. Drill and install small flat head screws to hold covers on.

Shroud or Eyebrows.
Some refer to the covers over the cylinders as eyebrows or a shroud. Please refer to the attached PDF for a pattern for making the parts. I formed the parts from thin plastic and roll it to get the curved shape. For connecting the two parts, I use small sections of light cloth glued to the inside with CA. Drawing for CUBEYEBROW.pdf

Details
Details can continue on from make clamps to spark plug wires

Making of Continental Engine

Close-up views of Continental Engine

www.thecubden.org

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