DOGFIGHTERS, The

Model Airplane News, May 2004 by Sparks, Keith

A pair of lightweight WW I backyard flyers

This construction project actually started three years ago when I built a foam version of the British S.E.5 and offered it as a kit. Soon, there was a demand for a foe, so I built the Fokker D.VII and marketed that. The two planes look completely different but fly pretty much the same. When I realized that my hobby had become a second job, I stopped making the kits, but It seemed a shame not to share these two great WW I backyard flyers with others, so I went to work on the plans.

TOOLING

Before you can build either of these allfoam models, you must build three hot-wire cutting tools, a wing cutting board and forward and aft fuselage cutting tools. To cut the wing panels, attach the wing templates to the ends of the cutting board. Place the 2-inch-thick foam block between the templates and make the first cut. Place a 1/4-inch shim under the foam block, and make the second cut to produce the first wing panel. Continue this sequence three times. Use a 3/8-inch shim to make the wing center sections.

The forward fuselage cutting tool is really two tools in one. First, place the foam block between the outer templates on the cutting board and then, after you've made the first cut, replace the templates with the inner cutting-line templates, and then make the final cut to complete the part. The aft fuselage cutting tool is used in much the same way as the forward tool, with the exception that only one end template is used. The other end is held stationary to form a tapered section.

To cut the flat fuselage side panels, the tail feathers and the wing jigs, make the patterns shown on the plans, and use them to cut parts out of 2-inch-thick blue foam. Suspend the cutting wire 1/4 inch above the tabletop with brass tubes. Slide the heated wire through the shaped foam to make as many parts as you want. Alternatively, to save material, you could slice the foam into sheets and cut out each part individually.

CONSTRUCTION

To prepare the parts for construction, trim the wing panels to shape and sand a radius around the wing edges and tail feathers. Do not sand where the wing will be bonded to the wing center section or where the vertical fin will be glued to the fuselage. Check the fit between the forward fuselage section and the aft tapered section; a little sanding might be required. Apply epoxy to the inner edge of one end of the fuselage, and then tape both sections together until the epoxy has cured (use very little.) If epoxy | oozes out of the seam, clean it off with rubbing alcohol and a paper towel. If you don't, it will be difficult to sand off later. Glue the sides to the upper fuselage half. Note: make sure that the forward side edges are flush with the forward top section edge. Glue the area forward of the cockpit first and then the aft end.

Note for the Fokker D.VII: the last few inches of the tapered section should not be glued until the stabilizer is in place. Then bond the sides together at the tail. Install the seatback and instrument panel. Poke two small holes in the skin from the inside so you will know where to position the cockpit holes.

Wings. To assemble the wings, put their center sections flat on the table, and check the wing panels' fit to the center joint by supporting the wingtips above the tabletop (see the plans for the distance). The tops of the wing panels are bonded flush with the top of the wing center section. Apply epoxy to the edges of the wing panels, and hold them with tape until the epoxy has set. Do not worry if the panels droop when the support is removed. With the bottom wing flat on the table, test the fuselage-to-wing fit. Then draw a centerline on the lower wing center section. On both sides, measure out from the centerline 1 1/2 inches and draw two more lines. This is where the outer edge of the fuselage will be bonded to the wing. The distances from each wingtip to the tail should be equal as should the distances from the wingtips to the sides. Now bond the fuselage to the wing using the lines you drew to position the pieces.

Cabane struts-S.E.5a only. Refer to the plans, and lay out the cabane-strut exit points on top of the fuselage. Mark their locations by using the end of the cabane strut sticks to dent the skin. Use a new no. 11 X-Acto blade to remove the dented foam. This allows the cabane struts to enter the fuselage and to be bonded to the lower wing center section inside the fuselage. Sharpen the tips of the struts, and then push them into the openings in the fuselage. Push them halfway into the wing center section and through the areas where the sides meet the wing. To prevent them from going all the way through, support the wing center section while you push the struts in with your finger. The struts should touch where they cross. Apply epoxy inside the openings, install the struts, and epoxy them where they cross. Attach the wing jigs to the fuselage sides with tape, and then place a straightedge across them to mark the final strut trim line.