along the wire to prevent paper from becom- ing permanently stuck to the wire. When the dope has dried, remove the tube from the wire and cut the tube into pieces for the wing mount, landing gear mount, wheel hub and propeller hub.
CONSTRUCTION: Lay out the parts of the wing, stabilizer and fin on the plan, ad- hering them together with a small amount of cement at each joint. When the glued joints on the wing have dried, crack the edges at the three dihedral joints and raise each wing panel as shown on the front view. Cement these joints well.
Attach the wing mount tubes to the left side of the body and cement the landing gear tube to the left side of the forward wing mount tube. Glue the propeller thrust bear- ing and the rear hook to the body, making certain that they are securely attached. Ce- ment the axle wire to the landing gear strut. Round off the edges of the propeller blades and cement the 1⁄16″ prop spars into the slots in the blades. When the cement has dried, soak the blades in water and wrap them around a can or jar, as shown in figure #1. Al- low the blades to dry completely before un- wrapping them. Pierce the center of the wheel and cement the paper tube hub in place. Cut a 1⁄8″ long piece of 1⁄16″ round, coat it with a light coat of glue and push it to the middle of the prop hub tube. Pierce the tube for the prop hook and push the hook, cement- ing it securely and making sure that the tube is at a right angle to the shaft of the hook. Cut the wing mount struts (D, E) to length and adhere them to the edges of the wing, making sure to get them at the angles shown in the front view. This angle will give
a small amount of twist to the wing when it is mounted, to help prevent the “Apprentice” from “spinning-in” in tight turns. Cover the top surfaces of the wing and sta- bilizer, and one side of the fin, with condens- er paper (Jap or Superfine tissue may be substituted if no condenser paper is avail- able). The wing must be covered in four pieces, one panel at a time. Use dope or thin shellac to fasten the tissue. Mount the stabi- lizer on top of the body, and the fin on top of the stabilizer, using a drop of cement at each edge and taking care to position them at right angles to each other. Check the fit of the 1⁄16″ round struts and
spars into their tubes, sanding the struts smaller or squeezing the tubes slightly as required. Assemble all the pieces, putting the bead and washer on the prop shaft be- fore putting the hook through the thrust bearing. The pitch of the pro- peller blades may be set by eye (so that each blade is at the same angle to the prop shaft) and may be adjusted to suit the flight pat- tern desired. Usually, the high- est pitch which will permit the model to climb to the ceiling is close to the most desirable. The “Apprentice” is powered by a loop of 3⁄64″ rubber, nice and fresh, about 13″ long, longer or shorter loops and lighter or heav- ier rubber may be used to vary performance. The length of the loop should be as long as possible while permitting the prop to run out all the turns in the air. Wind the motor using a winder, about
300 turns should do for the first flight, with more added as the model is trimmed out. The “Apprentice” should fly in left circles under power with no adjustments other than those which were built in. If adjust- ments in the turn are required, make them by bending the thrust bearing to change the direction in which the prop pulls the model. If the model dives, push the rear wing strut down in its tube and cure a tendency to stall by pushing the front strut down in its tube. Trimmed properly, it will takeoff from the floor and fly smoothly in 12 foot diameter circles up to the ceiling, bumping there for a few seconds and then coasting down for a landing. •
Paddle bladed prop of sheet, wrapped around can.
FLYING MODELS
33
FM DATA SHEETS
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