Mini Fokker D-VII

Model Airplane News, Oct 2003 by Tanzer, John

In April 2003, Model Airplane News published an article and a plan for my .20-size Sopwith Camel. I thoroughly enjoy the way these smaller biplanes fly, so I came up with a companion for the Camel in the form of the infamous Fokker D-VII-my favorite German WW I fighter. Designed around the Magnum .30 4-stroke engine, this little bipe has a 38-inch span with a flat-bottom airfoil for easy wing construction. After years of flying giant-scale, I really appreciate the ease and convenience of airplanes that can be stored and transported fully assembled. These two dogfighting favorites are truly no-hassle modeling at its best!

CONSTRUCTION

Wings. Both wings are built flat on the work surface; you can stack-cut the ribs out of 1/16-inch balsa sheet. Remember to cut holes in the top ribs for the aileron-servo extensions. Cut the trailing edge out of a single piece of 1/8-inch balsa sheet. Pin down the 1/8x3/16-inch spruce spar on the plan. Use a rib as a guide to position the trailing edge and pin it down.

Now glue all the ribs into place. The lower wing has two, 1/4-inch-thick ribs in the center. Glue in the top spars and the 1/4-inch-square balsa leading edge. Glue the 3/8-inch balsa strut-mounting blocks into their proper places. Remove the wings from the building board, and glue in the 1/16-inch balsa vertical-grain webs. Now cut the ailerons out of the top wing, and face the openings and the front of the ailerons with 3/32-inch balsa sheet. Add 1/4-inch balsa doublers to the aileron tips. Glue soft balsa blocks to the wingtips and then sand them to shape. Install the aileron servos; I used BP-102BB microservos. This finishes the wings for now.

Fuselage. Before you start the fuselage, make 3/16-inch, laminated-balsa plywood. You'll need three sheets of light 1/16-inch balsa; cut one sheet into 4-inch squares. Lay wax paper on a flat work surface; lay out the bottom balsa sheet and the 4-inch squares, and spray them with 3M Super 77 adhesive. Keeping the joints tight, stick the 4-inch squares to the bottom sheet (cross-grain). Now add the top sheet, having sprayed it and the cross-grain sheet with 3M adhesive. Press the top sheet on firmly, and let the balsa lamination dry overnight before you cut out the parts.

Cut the fuselage side pieces and formers out of the balsa ply. The sides are built on the plan with 1/16-inch-square longerons, uprights and diagonals. Build the second side on top of the first. When you've finished the sides, cut the engine mount, the bulkhead and the wingbolt plate out of 1/8-inch aircraft plywood. Make two, 1/4-inch-plywood landing-gear mounts. Cut the 3/16-inch-square balsa crosspieces, and pin them to the top view of the plan. Insert the engine mount and the bulkhead into the slots at the front of the fuselage, invert the fuselage over the crosspieces, and pin it down.

Glue in the landing-gear mounts, the wing-bolt plate and the 3/16 x 1/2-inch balsa crosspiece at the rear of the wing saddle. Use CA on all of the joints, and make sure that the sides are square. Pull the rears of the fuselage sides together, and glue in the bottom crosspieces.

While the fuselage is still inverted on a level work surface, trial-fit the lower wing. Check that the wing is level by measuring from the work surface to the wingtips. Use a Robart Incidence Meter to check the wing for 0 degrees' incidence. Sand the wing saddle, and then drill an 1/8-inch hole in the leading edge and install an 1/8-inch dowel. Glue the 1/32-inch-ply wing-bolt plate to the rear of the wing. Place the wing back in the saddle, and check its alignment by measuring from each wingtip back to the tail (the sides should be the same length). Drill the wing, and tap the bolt plate for a 10-32 plastic bolt. Remove the wing, and harden the bolt threads with CA. Remove the fuselage from the plan, and cut the deck and cowl formers out of 3/16-inch balsa ply. Glue the formers to the fuselage top forward to the cowl separation point, and then sheet the top with 1/16-inch balsa. Sheet between the landing-gear mounts, and fill in the lower front with balsa blocks. Next, make the upper cowl, and sheet it with 1/16-inch balsa. Make the radiator out of balsa blocks, and glue it to the upper cowl. An aluminum screen is fitted into the radiator. The cowl and radiator are removable and are keyed with 1/8-inch dowel pins.

For flight, pull a rubber band over the rear of the cowl to keep it in place. Glue the 1/64-inch-ply side panels onto both sides. Mark and drill 1/16-inch pilot holes for the cabane struts where indicated on the plans.

Struts. Make the two inter-plane struts out of 1/8x 1/4-inch spruce. Use the diagram on the plan, as they must be made accurately; they will set the location of the top wing. Be sure to make a left and a right. Cut slits in the ends, and glue in sheet-tin angle brackets. After you've shaped the struts, wrap their ends with thread and saturate them with CA. Drill holes in the brackets for no. 2 socket-head screws. Drill 1/16-inch pilot holes in the balsa wing-strut blocks.