Author: P. Bosak
Edition: Model Aviation - 1982/09
Page Numbers: 72, 73, 74
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RB-59 Gladiator

An eye-appealing R/C sport plane by noted Czechoslovakian designer Pavel Bosak. The RB-59 Gladiator was designed as an intermediate trainer/sport flier that looks as much like a full-size airplane as possible. It is stable and not tricky, making it ideal for relatively new fliers and for Sunday/sport flying, yet it can perform most intermediate aerobatic maneuvers.

  • Designer: Pavel Bosak

General characteristics

  • Controls: three-channel — elevator, engine (throttle), and linked rudder/nose wheel (steerable).
  • Recommended power: .15 cu in engine (use .19 cu in if converting to floats/seaplane).
  • Construction: primarily balsa with spruce spars and plywood braces; foam wings are also feasible using the rib templates on the plans.
  • Features: large bubble canopy (plans show how to form it), cockpit details and pilot/passenger figures greatly enhance realism.

Wing

The wing has no ailerons, making it straightforward to build. Ribs are tapered and formed by the interpolation method.

Building the ribs (interpolation method)

  1. Cut plywood templates for the center and tip ribs.
  2. Prepare 12 balsa rectangles (slightly oversize, grain lengthwise) for one wing half.
  3. Sandwich the balsa rectangles between the plywood templates, drill two alignment holes through the sandwich, and bolt the pieces together.
  4. Carve and sand the balsa rectangles to match the plywood templates (do each wing-half separately and oppositely).
  5. Cut two main wing spars (W-16) from 3/16-in. balsa.

Wing assembly

  • Build the wing on a jig with the leading and trailing edges blocked to the proper height to prevent twists or warps.
  • Cement ribs in place along with the balsa and spruce spars, and install the leading and trailing edges per the plan.
  • Join the two wing halves with 3/32-in. plywood wing braces (W-15).
  • Apply 3/32-in. balsa sheeting, cap strips, and wing tips.
  • When dry, sand the entire wing smooth.

Note: Foam builders can use the two rib templates from the plans as cutting patterns.

Stabilizer and Fin

  • Can be built-up as shown on the plans or shaped from 3/16-in. sheet balsa.
  • Elevator and rudder are made from sheet balsa.
  • Ensure the stabilizer is square and set at 0° incidence relative to the fin.

Fuselage

Preparation and parts

  • Cut out all parts, starting with formers.
  • Strengthen fuselage sides with 1/32-in. plywood doublers.
  • Use a commercially available engine mount or cut one from 1/4-in. plywood.
  • Attach steerable nose wheel assembly F-3.
  • Prepare the fuel tank for installation.

Assembly sequence

  1. Cement formers between fuselage sides; add the vertical fin during this stage.
  2. Plank the fuselage bottom and top rear with 3/16-in. balsa.
  3. Install forward pushrods and the fuel tank before planking the upper forward section.
  4. Sand the entire fuselage, then cut the slot for the stabilizer and glue it in place, ensuring it is square.
  5. Glue in wing rubberband dowels and small plywood doublers.
  6. Install the main landing gear (typically made from 1/8-in. aluminum, or a ready-made gear may be used).

Canopy / Cockpit

  • Study the canopy sketches and use top-view templates A–C for the die.
  • Allow for the thickness of 1/32-in. Plexiglas (or chosen plastic) when making the die and punch.
  • Warm the plastic canopy material, place it over the die, and pull down with the punch to form the shape.
  • After cooling, remove the punch, trim flashing, and fit the canopy to the fuselage.
  • Glue end formers and glue the canopy in place.
  • Add cockpit details and pilot/passenger figures to greatly enhance the model’s appearance.

Finishing

Suggested finishing sequence (one recommended method)

  1. Apply two coats of clear dope, sanding after each coat.
  2. Fill small gaps and dents; apply filler (example: talcum powder mixed with clear dope) and sand smooth.
  3. Apply another coat of clear dope and cover the model with thin silkspan.
  4. Apply six coats of clear dope, wet-sanding with No. 400 paper between coats.
  5. Apply color coat(s) as desired, then a final coat of clear fuel-proofer.

Follow your preferred finishing method if different.

Final assembly

  • Attach main landing gear and engine.
  • Hinge rudder and elevator; install servos and pushrods.
  • Connect engine throttle and steerable nose wheel to their servos.
  • Check the model's center of gravity and adjust with ballast as necessary so the plane balances at the location shown on the side-view plan.

Flying

  • First flights are easy if flying surfaces are straight (no warps/twists) and the model is properly balanced.
  • Taxi the model with the rudder neutral and adjust the nose wheel for small directional corrections.
  • If it taxis straight, attempt takeoff; the model should lift off without control input once at flying speed. Experienced fliers can lift off sooner using elevator input.
  • The Gladiator performs all intermediate maneuvers, including outside loops. To induce a spin give full rudder and elevator; recovery is by neutralizing controls.
  • Club members have reported successful first flights on several Gladiators.

Final note: It would be interesting to try a Gladiator with ailerons, but that is a separate modification. Good flying hours to anyone who builds the Gladiator.

Transcribed from original scans by AI. Minor OCR errors may remain.