16.1. Event 422: Quarter 40
16.1.1. Airframe
a. Weight. Minimum four (4) pounds, maximum five (5) pounds.
b. Wings.1) Area: Minimum 400 square inches.
2) Span: Maximum 56 inches (projected).
3) Chord: No limit.
4) Airfoil thickness: Minimum 7/8-inch at the "no-go" point (see paragraph 3.8.). Thickness shall progress uniformly in a straight line or convex taper from root to tip; except that, if the full-scale prototype has a different progression, the progression on the model may be similar. The wing taper, in addition to other distinctive design features, is subject to the design approval requirements of paragraph f. below.c. Fuselage.
1) Depth: Minimum five (5) inches at its deepest point; except that models of P-51s and other full-scale prototypes with belly-mounted radiators shall have a fuselage depth of at least six (6) inches. Depth includes the radiator or belly scoop (if any) and the windshield, canopy, pilot’s head, or headrest, but does not include tail surfaces, dorsal or sub fins, tail skids, or non-scale protuberances.
2) Width: Minimum three (3) inches at its widest point. Width and depth points need not coincide. Width does not include fillets, cheek cowl fairings, or non-scale protuberances.
3) Cross-sectional area: At some point, the cross-sectional area of the fuselage shall be at least 12.5 square inches, and the contestant shall be required to furnish templates to prove this. Fillets and cheek cowls are not to be included in the measurement.
4) Cross-sectional shape and features:(a) Profile representations of any significant feature of the full-scale prototype are prohibited. Cross-sectional contours at the height and width measurements and at stations determining the likeness to the full-scale prototype shall maintain the integrity of the contours in the full-scale prototype. The only exception permitted shall be in the engine compartment for maintenance purposes.
(b) Cheek cowls, canopy, and belly scoop, if any, shall have at least a 5/8-inch radius at their widest point so that a hypothetical 1-1/4 inch-diameter ball would fit inside, tangent to the outer surface. A cowl, canopy, or scoop with an oval or rectangular cross-section and corners of less than 5/8-inch radius satisfies this requirement if the hypothetical 1-1/4 inch-diameter ball would be fully enclosed.
(c) Removable cowls are prohibited. The front end of the fuselage shall be configured so that the engine head and cylinder protrude on all sides at least 3/4 inch, not including the glow plug, and the muffler is fully exposed for its entire length. However, the fuselage may incorporate a shallow channel, dimple, or trough to provide clearance for the muffler. In addition, the access hole for the engine crankcase and mounting lugs may be covered with a piece of fiberglass, Mylar®, or other stiff material, not more than 0.020 inches thick, that restores the original contours of the fuselage in that area.
d. Landing gear.
1) Location and size: The landing gear shall be fixed and shall resemble that of the fullscale prototype aircraft as to location on the airframe and the number of wheels used. At least two (2) of the wheels shall have a diameter of at least 2-1/4 inches.
2) Streamlining: Wheel pants, wheel spats, or strut fairings are not required, and are permitted only if they were used on the full-scale prototype.
e. Replica rule.
Models entered in this event shall be recognizable replicas of full-scale, human-carrying, propeller-driven aircraft that either raced in or were built for closed-course or cross-country racing or a speed record attempt.
f. Prior approval of designs.1) Procedure: All designs, past and future inclusive, shall not be entered in competition until three (3) accurate views or photos of the model and the full-scale prototype aircraft have been submitted to a five-member subcommittee of the RC Racing Contest Board and approved by an affirmative vote of at least three members thereof. Such approval may be given orally, but shall be recorded for future reference. In the case of unusual or little known designs, the designer shall produce documentation to clarify that such a design did exist. A model shall be considered eligible for competition if it meets all dimensional requirements of these rules and, in addition, does not vary significantly from the approved three-views or photos of the same design.
2) Membership of committee: The five member committee shall be appointed by the Chairperson of the RC Racing Contest Board and may consist of any five members, including the Chairperson, who do not have a financial interest in any kit manufacturing business that produces airplane kits for this event. If a design has been disapproved by the five-member subcommittee, the designer is entitled to review by the entire contest board.
16.1.2. Powerplant
a. Engine.
1) Maximum displacement: 0.403 cubic inch.
2) Configuration: Stock, commercially available, front-intake, side-exhaust.
3) Intake: A single carburetor or venturi with a maximum inner diameter of 9 mm (0.3543 inch). Carburetors or venturis may be modified and are not subject to availability rules.
4) Exhaust system:(a) General description: The engine shall be equipped with an expansion chamber muffler, zero-boost muffler, or tuned muffler as provided by the manufacturer for the engine being used, and having a single exhaust outlet with a maximum outlet area of 0.0621 square inches (equivalent to the area of a round hole measuring 9/32 inch in diameter).
(b) Inner configuration of tuned mufflers: A tuned muffler used in this event shall have only one internal part, a straight tube or extractor of the type commonly known as a “mini-pipe”. The mini-pipe shall have a constant, circular cross-section and constant inside and outside diameter, with the following exception: the sidewall of the tube may be thickened, not to exceed 1/16-inch wall thickness, within 1/2 inch of the front end of the mini-pipe where it attaches to the header.
(c) Outside dimensions: The distance from the center of the piston to the centerline of the muffler shall not exceed 2-3/4 inches. The overall length of the muffler shall not exceed 7-1/4 inches, measured from the front of the header to the back of the exhaust outlet. The outside diameter shall not exceed 1-3/4 inches, and both the inside and outside diameter of the outside shell of the muffler shall remain constant for at least 4-1/2 inches.
(d) Modifications: No modifications to the muffler are permitted except that the muffler may be tapped for a pressure fitting to supply pressure to the fuel system.
5) Fuel feed: Other than muffler pressure, no fuel system pressurization is permitted.
b. Propeller.1) Material: Wood.
2) Dimensions: No limit.
c. Fuel.
The fuel shall be commercially available, containing not more than 15 percent nitromethane, and shall be supplied and dispensed by the hosting organization. The dispensing operation shall include draining the tank of any existing fuel and then filling from a supply container when the pilot brings the aircraft to the ready box.