Airfield Models - Fuselage Construction Example

Making the Engine Cut-out and Shaping the Nose of a Model Aircraft Fuselage

May 03, 2015



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Airfield Models (http://www.airfieldmodels.com/)Making the Engine Cut-Out and Shaping the Nose

I do not know what it is about making engine cut-outs, but I just do not like doing it.  In the past I always tried to make the cut-outs as small as possible so they wrapped neatly around the engine.

What this resulted in was a lot of frustration trying to make adjustments to the throttle linkage as well as cut-outs that had chunks taken out of them from repeatedly taking the engine in out and working with tools in the area.

Now I make my life simpler by making the cut-outs large enough so that I can work easily in the compartment and not worry about it.

 
 
The cut-out for the engine is large enough to allow work to be done around the engine without damaging the wood. This was what the cut-out looked like initially.  The only part that I really do not like is the upper edge of the cut-out (right side of photo) which would have looked better if it were a straight line.  Other than that it is not horrible.

I can get the engine and mount in and out easily and there is room to work around the engine without damaging the wood.

Note the triangle stock in the engine compartment.  This is what allows the nose to have a streamlined shape.

The engine mounting bolts are most easily accessed through the nose ring. All the engine mount bolts are secured through this opening.  They can be reached easily with a hex driver (not an Allen key).

If you look carefully, you can see where the engine mount has been relieved to prevent interference with the fuel lines.  The other option was to drill the holes in a different location.  However, the holes line up with the tank where they are and any other location would invite kinking and fuel-feed problems.

This was a problem that I solved when I was building the firewall before it was glued into the structure.  I can not stress strongly enough the importance of fitting anything and everything before gluing it in place to prevent untold amounts of frustration.

The engine shown mounted in place.

The next step is to glue on the spinner ring and shape the nose.  The engine has to be mounted before the ring can be glued on.

This is an O.S. .52 Four-Stroke.  The rear mounted carburetor makes hooking up a throttle linkage a challenge.  There is not room between the firewall and the carburetor for a clevis.  A Z-Bend will be difficult because the engine has to be removed by pulling the back out first which means the wire will bend too much.

My buddy, Mike, suggested that I use music wire with an L-Bend that is sprung so it will engage the throttle arm without using any type of connector.  I did it and it works great!

The nose ring checked for fit before gluing. Apply glue to the ring and center it around the prop shaft.  Slide the spinner backplate on the shaft to align the ring.
Scraps of plywood are used to fill the space between the spinner backplate and the nose ring. Use scraps of plywood to act as clamp blocks.
The spinner backplate is used to clamp the nose ring in place. Put the spinner backplate on with a propeller and tighten it all down to clamp the ring while it dries.
The nose is planed to roughly fair it into the nose ring. When the ring has dried, remove the engine.  Plane, carve and sand the nose to shape.
The nose after final sanded with the spinner in place. Continue sanding until the nose has a nice flowing shape to it that fairs into the spinner at the front and into the box fuselage further back.
The nose after final sanded with the spinner in place. Another view of the nose.  This is a Fox Slim Jim spinner.  I also have a Fox Conical spinner of the same diameter.  I think the conical spinner will look better, but I will wait until the aircraft is finished to make that decision.

I do not see these spinners listed on the Fox web site so they may be out of production.

 
 

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Adding Upper and Lower Decking to a Model Airplane Fuselage
Installing the Onboard Radio Gear (Flight Pack)

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Copyright 2003 Paul K. Johnson