Building the (Old) FLYLINE Great Lakes 2T-1A Kit (24)

With the model covered, clear doped and primed, just about ready for color, there are a few more details I need to take care of before that final paint job can begin. The one I want to tell you about this time provides a perfect example of the way building scale model airplanes is in large part about an unending series of choices. How accurate should I make it…where does enough detail start turning into too much weight…which of those high cool factor features can I build well enough that they won’t become liabilities waiting for a chance to break?

In this case it’s about a fuselage exterior characteristic that is common to so many classic tube-and-fabric airplanes. Very often the fuselage is fabric covered from someplace near the leading edge of the wing all the way back to the tail, and from the leading edge forward to the rear of the engine cowl the outer skin is made up of several sheet metal panels attached with a variety of screws and brackets in order to be easily removeable for access to what’s underneath. For the model builder the easiest approach is just to build the fuselage with simple flat sides…but…some effort invested in making the model look as if it is fabric covered in one place and metal skinned in another goes a long way. If this model were intended for scale competition I would have reproduced the whole deal, with each panel built as a separate part and fastened with scale-sized hardware, but that’s not what this little Great Lakes is for. I have covered the entire fuselage with Polyspan, firewall to tail, and I’m going to simulate the metal part by adding a single panel of thin aluminum sheet to each side of the nose behind the removeable cowl. Here’s how it works.

This is the front of the fuselage, upside down. The flat plate with the opening is the bottom of the motor mount box and the tube-and-rod-end assembly is the lateral main gear member we looked at earlier. Each side of the nose from the firewall back to the lower wing cutout is going to be covered with a custom made aluminum panel to represent full scale structure.

Most of the time the best way to represent sheet aluminum skin on an airplane is to use sheet aluminum. Designing and creating a load bearing metal structure is a big deal and beyond the abilities of most of us...but...for the purposes of model building a traditional structure of balsa, plywood, etc., covered with a cosmetic, non-load-bearing piece of sheet aluminum will work just fine. If you permit the aluminum to serve as the finish base for that part of the airplane, you can often end up with the scale appearance we are looking for with little or no weight gain over a more simplistic approach to detailing. For many years the classic source of thin, light aluminum sheet for jobs like this has been "lithoplate"...leftover aluminum offset printing plates from the printing industry. Lately aluminum plates have become less and less common, but there are other ways to go. The K&S line carried by better hobby shops now includes various sizes of thin aluminum sheet. I have also had good results using "roofer's flashing" aluminum from the building supply store. If you are interested in this technique, I suggest that you shop around to see what is readily available in your area. On this airplane I am using a piece from my old stash of lithoplate. I have cleaned up the surface and removed the old photosensitized image areas with fine sandpaper, marked out the panel I'll need, and scored the outlines with a razor blade and straightedge.

Bending the metal back and forth along the scored lines will cause it to break cleanly. This workpiece is the sheet from which I will trim both of the side panels that will go onto the model.

Each panel requires a pair of holes to be cut to clear various parts of the landing gear assembly. I drilled each hole a bit undersize on the drill press using a smooth wood backing block to prevent distorting the sheet, then trimmed each hole to the necessary size and shape using a combination of files and sandpaper wrapped around various mandrels to create exactly the right size tool.

This is the right front of the fuselage. The main landing gear strut is in place, and the extra hole above it (to the right in the image) is where the little diagonal bracing strut will go. Each of the holes in the aluminum panel has been finished to the exact size required to fit in place.

Dressing the edges of a sheet metal panel for a more finished appearance is one of what I understand are referred to as "coining" operations in the sheet metal business. In this case I am scribing along the back face of the panel to create a beveled edge as seen from the front, or outside.

This is the finished panel after coining and cleaning up the cut edge with 320 paper. This is a detail that may not be exactly "scale" but I like including it on models like this one that will not be flown in competition for the finished effect it provides.

Here the left panel is in place on the fuselage. I used a thin coat of 30-minute epoxy as an adhesive. The masking tape is the best way I have found to hold assemblies like this one in place while adhesive cures. The other side is done the same way.

It's time to hinge the ailerons, rudder and elevator. I am using Robart 3/32" Hinge Points for their close resemblance to the steel-tube-and-bolt hinges used on the full scale Great Lakes. After locating the exact positions of each hinge on the various surfaces I drilled 3/32" holes to accept them.

The Robart hinges have a square cross section immediately adjacent to the hinge itself. I opened each of the 3/32" drill holes using a square file to get an exact fit when the hinges are assembled in place.

This is the right half of the fixed horizontal stabilizer mounted in place on the carbon fiber rod carry-through's I showed you earlier. I have already drilled all the hinge holes in this part.

I am going to use 30 minute epoxy to install each of the Robart hinges. A quicker curing adhesive might save a few minutes, but there is no substitute for taking the time to get the alignment just right on jobs like this. A drop of machine oil on the mating surfaces of each hinge assembly ensures that the epoxy will stick only where I want it to.

Here's the hinge in place ready for assembly of the elevator. At this point I clean up any excess epoxy from the exposed portion of the hinge, double check for free movement, and add a new drop of oil before applying epoxy for the final assembly.

The rudder and both halves of the elevator, which are connected by a dowel joiner, are hinged and ready for the next steps in finishing. Because the control surface separation gap on this airplane provides a convenient work space I chose to assemble all the control surfaces prior to doing the final paint work. This means tha I will have to do some minor clean-up of dried paint from the hinges, but it also permits me to handle each of the control surfaces as part of the assembled airplane and saves a lot of fussy jigging and handling of small components while I am painting.