10             AT-6/SNJ Class Specifications

10.1          Introduction

The following rules and specifications are for the AT-6/SNJ Class.  All Common Rules apply as appropriate.  The dimensions of the AT-6/SNJ Class aircraft are based on the current USRA Aircraft Specification Sheet and the AT-6/SNJ Class Rules that follow.

10.2          General

10.2.1               Aircraft are meant to be accurate scale models, which conform to basic scale outlines and are not meant to be "precision scale".

10.2.2               All entries must be a 1/5 scale (2.4" = 1') model of the full size, two-place, North American AT-6/SNJ aircraft.

10.2.3               No dimension may be less than the dimensions prescribed on the USRA AT-6/SNJ Specification Sheet.

10.2.4               Non-scale blisters, fairings, etc. are not permitted.

10.2.5               The trailing edge of the cowling will maintain a minimum gap of 1/4" around the entire perimeter of the firewall, i.e. the diameter of the cowling (at the trailing edge of the cowling) is 1/2" larger than the diameter of the fuselage at the firewall station.

10.3          Weight

10.3.1               Minimum aircraft weight is 25 lbs. (dry). Maximum aircraft weight is 40 lbs. (wet).

10.3.2               Aircraft weight may be verified at any time during a race.

10.4          Engine Specifications

10.4.1               Aircraft must use a stock, 3.7 cu. in., magneto ignition, Zenoah G-62ä. No modifications of any kind are allowed. This includes the removal of chokes, piston ring heating, porting, polishing, etc.

10.4.2               Any commercial brand of replacement spark plug is permitted.

10.4.3               Indexing of the spark plugs by using various thickness washers is permitted.

10.4.4               Straightening of the crankshaft is permitted.

10.5          Propellers and Spinners

10.5.1               USRA specified propellers will be supplied by the race promoter/event organizer.

10.5.2               No modification may be made to the propeller or propeller hub.

10.5.3               All aircraft must have a spinner. Spinner diameter may vary slightly to the closest commercially available size as long as scale size and shape are retained with a minimum diameter of 3 1/4 inches.

10.6          Exhaust Systems

10.6.1               Exhaust systems (headers, mufflers) must exit in the scale location.

10.6.2               Maximum length of the exhaust header/pipe from manifold to end is 8 inches regardless of how much of that is outside the cowl.

10.6.3               No tuned pipe or exhaust augmenters are allowed. The exhaust pipe may not be restricted (pinched) or otherwise altered.

10.6.4               Spark plug and spark plug wire may protrude neatly from the engine cowling.

10.7          Airfoils, Planforms and Control Surfaces

10.7.1               Wing and tail group airfoils must follow scale planform, chord area, thickness, etc., of the full size AT-6/SNJ aircraft and meet the minimums as indicated on the USRA AT-6/SNJ Specification Sheet.

10.7.2               Control surface dimensions may vary as long as the aircraft outline is not affected.

10.8          Canopy, Air Scoops and Pilot Bust

10.8.1               Aircraft must have a clear or tinted (not opaque) canopy. Typical tinting of the "greenhouse" panels is permitted.

10.8.2               Canopy panel lines must be shown in scale-like size and location. Panel lines may be either molded, painted or taped.

10.8.3               A near-scale 1/5 size pilot (human likeness preferred) will be installed in the cockpit.

10.8.4               Side air scoop is required. The bottom air scoop may be omitted if desired.

10.9          Landing Gear and Tail Wheels

10.9.1               Aircraft must have and use scale-like retractable main landing gear. Gear must be of sufficient size and strength to allow aircraft to repeatedly taxi to runway from the staging area, takeoff, land and taxi for recovery in a reliable manner.

10.9.2               Scale size main wheels (5" x 1 1/2" minimum) and a steerable tail wheel (2 1/4" x 1/2" minimum) must be installed in the scale location. Retractable tail wheels are not permitted.

10.10        Fuel

10.10.1            Engine fuel will be the only liquid carried in the aircraft.  Any foreign liquid, other than provided fuel, will be grounds for disqualification.

10.10.2            Fuel will be supplied by the race promoter/event organizer.  Fuel will be formulated and mixed according to the USRA T-6 Class fuel specification as stipulated in paragraph 4.10.4 of the Common Class Rules.

10.10.3            A means of defueling through the fuel supply line to the engine must be provided.

10.11        Drawings

Paul Matt drawings are used as a scale reference only.  The USRA AT-6/SNJ Specification Sheet takes precedence.  Paul Matt drawings are 1/2" = 1', 3 sheets, 17 x 22 and are available from:  Aviation Heritage Books, Sunshine House, Inc., P.O. Box 2065, Terra Haute, IN  47802  Phone: 1-800-999-0141

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Date :        11/01/97 Revision :   B Approved :  BOD

AT-6/SNJ Specification Sheet

                                                                                                                 MODEL MINIMUM