The Gun Deck

Aug 26 , 2006

Prep steps for the gun hood

OK, to start putting some "teeth" in this wolf, we have to get the gun deck together. I start this by laying out the gun hood and all other components that comprise this area. First step is to sketch out the basic outlines of the gun hood right onto the fuselage.

This process is done by carefully studying the associated shapes in my 3-views and plastic models. I find the 1/48 scale plastic models to be especially helpful in tasks like this as they give you the 3-dimensional insight that 2D drawings can't provide.

Also at this time, I sketch out the lines for the gun troughs (in the top of the cowl), and also the basic positions that the gun barrels need to occupy.

Once the outlines are sketched down I then cut and install the two primary formers. One at the front, right at the TE of the cowl, and the other at the rear, resting right at the LE of the canopy. The cowl slopes down from the taller rear former to the shorter front former, but not on a straight line. The intermediate formers that will follow are what determines the telltale 190 lines that make up that sloping shape.

With these steps completed, it's time to start the intermediate "transitional" formers of the gun hood.

Building up the hood

Now comes the fun part. I personally enjoy fabricating these types of nearly "organic" outlines on scale planes more than any part of the construction. The lines of the FW190 gun hood are very unique and play a big part in giving it the "sinister" look that is easily recognized on the Focke Wulfe.

To start, I lay down two large balsa sticks that span lengthwise from the rear former about 2/3 of the way to the front. I then skip ahead to the gun positions and make two balsa "tunnels" that the barrels will position inside. After that, it's a somewhat tedious process of studying the 3-views and plastic model to recreate the slopes and bulges of the 190 hood. These are all recreated in the form of balsa wedge formers that form the internal "skeleton" of the gun hood.

To add some skin to that skeleton, I then proceed to sheet it with 1/16" balsa planking. The first plank is 1-3/4" wide, and spans across between the two thick longitudinal formers. The edges of this plank split right down the centerline of each of these formers. After that, I begin planking down the left side of the deck using narrower 5/8" wide planks. This allows me to conform the sheeting more closely to the sharper contours as the deck rolls down the sides of the fuse.

Once the left side is done, I repeat the process down the right side. Note that no attempt is made to blend/feather the edges of the hood into the fuse. The gun hood has some pretty distinct panel lines in the real 190, and this will help me to recreate them. I did however sand the edges of the sheeting down to about 1/32" thick to make the relief more realistic.

Also note that the hood ends quite abruptly at the front and back ends. The step-down at the front will be where the cowl overlaps, allowing it to blend into the fuse. At the rear, I'll need to add more structure to blend the hood back and up into the canopy area.

Blending back

After placing the canopy back on the fuse to get another look at how this was all coming together, and also reviewing the plastic model some more, I started framing up the triangular area that blends the gun hood at the rear. Again, distinct panel lines need to remain between this area and the hood itself, so a slight gap is maintained there.

Once the framework is laid down, I then apply a thin balsa ledge inside the framework. I can then sheet the area, with the sheeting butting up to the inside edges of the framework and resting on the thin ledges. The bottom edge just lays right on the fuse, with a small 1/32" relief being maintained. With a little putty and eventual glassing, this will look like one solid panel.

Fabricating the MG131 gun barrels

For a really high-end competition model, I suppose I would have had these barrels milled/lathed from metal. But, this is going to be an every day flyer that doesn't warrant that level of effort/expense. Therefore, I decided to make the MG131 gun barrels myself from more conventional materials (which is more fun anyway).

I started with a small piece of 3/16" wooden dowel rod. I used a drill press to drill the holes in the two ends of the dowel, beginning the shape of two gun barrel ends. This hole doesn't need to be too terribly deep... about 3/16 - 1/4 inches should do it.

Next I chuck the dowel up in the drill press as if it were a drill bit, then use a file and sanding block to "lathe" the flanged shape at the two ends. Next, I cut the two ends apart from one another (disposing of the center connecting section) and taper the "butt ends" slightly. This allows me to glue each into a small section of 1/4" styrene tube.

Lastly, I glue the styrene tube over the ends of a couple sections of 7/32" brass tube. The finished barrels then provide me the proper scale steps in diameter and shape. Once primed, cleaned up and painted, these should work just fine for this bird.

Gun trough mod in the cowl

Now we need to give the gun barrels somewhere to live. The stock JDM cowl does not have the gun troughs formed into it, so you'll have to modify it to get them in place. Following the outlines I had drawn on the cowl earlier, I used a Dremel to cut out the long teardrop shaped channels in the cowl for each barrel.

Next I had to come up with some sort of structure to form the "valleys" of the troughs/channels. To do this, I used cardboard "aileron extension" tubes. After cutting them to length, I split them lengthwise at an angle. This "wedge" of tubing would work perfect for the bottoms of the troughs.

After spot gluing them in place from the inside of the cowl, I scuffed up the surface of the tubes with some sandpaper. I then mixed up some epoxy and microballoons to create a "putty" that I could spread heavily over the surface of the cardboard (using my finger). This helps blend the tube into the shape of the cowl, adds great bonding strength to secure the tubes in place, and ultimately gives you a paintable surface.

Once that was dry, I glassed the tubes from the inside of the fuse by spreading a large square of heavyweight fiberglass cloth over the area and applied a few coats of epoxy. With a little spot putty and sanding, the troughs came out quite nice.

Lastly, I had to figure out a method for installing the gun barrels in the hood. I attached a balsa plug at the back ends of each gun barrel, shaping them so that they fit snugly inside of the tunnels in the hood. After testing the fit and making sure that I could get the cowl on and off with them installed, I removed them until final installation (after the plane is done and painted).

Finishing it all up

One last step was to add another scale panel that spans the area between the bottom edge of the gun hood and the top edge of the engine vent slots. This really adds that last touch of scale outline to the front end of the fuse and helps to accentuate and augment the slots. These too are distinct panel lines that I can maintain after glassing.

At one point I researched an aftermarket fiberglass gun hood for this plane but could not find any available or in stock. Ultimately this method worked out just fine, gave me great results and was more rewarding to accomplish.

The finished gun deck looks quite convincing, is very light, costed me virtually nothing to construct and was actually quite fun to fabricate. It certainly looks better than leaving these features out, and with some more surface detailing and final shaping, I think it's going to come out just great.

"control surface installation"