Northwest Sport Race engine rule change approved

Voting allows use of O.S. LA .25 engine along with Fox .35 Stunt

The O.S. .25 LA engine will be allowed in Northwest Sport Race and beyond as a result of Northwest racing fliers' appropal of a proposal by Mike Hazel.

Since its inception more than 30 years ago, the current version of Northwest Sport Race has allowed only the Fox .35 Stunt engine in stock configuration. In some areas of the country, the O.S. LA .25 has been allowed in races that traditionally were limited to the Fox .35. Hazel's proposal was to extend that provision to Northwest Sport Race.

In voting concluded on Feb. 4, 2014, Northwest competitors approved the change by a vote of 70 percent to 30 percent.

As a result of the vote, the rule is effective for 2014 and beyond.

Summary of change:

Amends rule No. 3 to to include the LA .25 in stock configuration. Exact wording is highlighted in the rules published below.

Rationale: Mike Hazel writes: "Although the Fox Stunt .35 is readily available, there are those who may not prefer its “characteristics.”  The O.S. LA .25 is also readily available, and of a similar level of power.  By having a choice of engines it is hoped that participation in the event may be enhanced.

Approved 2014 Northwest Sport Race rules
New language in red; deleted language in strikeout


1. Purpose: It is the intent that that this event will provide the novice competitor a beginning racing event, racing with other competitors using similar equipment which is readily obtainable and operates in a basic fashion.

2. All pertinent rules from AMA unified racing rules shall apply, in regard to safety and conduct of races, except as follows.

3. Engine: The only allowed engine shall be the Fox stunt .35, which shall be a stock, unmodified engine operated on suction feed. ("Stock" is defined as absolutely unmodified except for needle valves and spray bars.) No exhaust extensions are allowed except bona fide mufflers that do not increase engine performance. The Fox Manufacturing Co. hemi/stuffer kit modification is prohibited.

3. Engines:  The only allowed engines shall be the Fox Stunt .35, and the O.S. LA .25,  both of which shall operate on suction feed and be in stock, unmodified condition except as follows:
a. “Stock” is defined as absolutely unmodified but making exceptions for needle valve assemblies, engine assembly bolts, gaskets, prop nut, and prop washer(s).  Additionally, intake venturi must maintain original factory stock dimension.
b. No exhaust extensions are allowed except bona fide mufflers that do not increase engine performance.
c. Other: The Fox Manufacturing Co. hemi/stuffer kit modification is prohibited. The O.S. LA .25 may have the rear needle valve assembly post removed, and may also use a substitute backplate.  The RC version of the O.S. LA .25 engine may be used, by fixing the throttle in one position.

4.1. Aircraft: The model shall be built from, or an exact duplication of, a commercially manufactured kit. In the case of obscure or rare kits, some documentation, such as a set of plans, may be required by the contest director for confirmation of the airplane's kit status. Kits need not be in current production or distribution to qualify.
4.2. Models must be of profile fuselage type, and must conform to the general profile definition. The model must have a minimum fuselage length of 24" when measured from the propeller thrust washer face to the leading edge of the movable elevator surface.
4.3. The minimum wing area shall be 300 square inches. The wing must have a minimum thickness of 1 inch when measured at any point along the span, with the exception of the last two inches before each wingtip.
4.4. All models must have a canopy, horizontal stabilizer, elevator and vertical fin. Models must have a fixed landing gear with a minimum of one wheel, 2 inches in diameter or larger.
4.5. Modifications: Major changes to the kit design such as clipped wings, shortened fuselage, partial omission of the tail assembly, etc., are prohibited. Reinforcement of the nose and engine mount areas is permitted. Landing gear location and construction are entirely optional from what may be included in the kit, except as specified in section 4.4.

5. Fuel tank: The fuel tank shall be fully external and forward of the wing leading edge, and located on the outboard side of the fuselage. The tank may not be designed so as to cowl the engine. All tank vents are limited to a maximum size of 1/8-inch outside diameter. The tank may not be pressurized, but the vents may be directed forward into the airstream.

6. Prohibited equipment: Equipment and devices standard to full-race aircraft are prohibited. These include fuel shutoff, pressure refuelers, fast-fill systems, "hot glove" electrical contact systems, and centrifugal carburetor switches.

7. Pull test: The plane and entire control system shall undergo a pull test of 35 pounds.

8. Lines shall be of a minimum .018-inch diameter, and lines shall be of the stranded type, with a length of 60 feet measured from the handle grip to the fuselage, plus or minus 6 inches.

9. Races: Preliminary heats shall be of 70 laps duration, with one pit stop minimum required. Feature races shall be of 140 laps with two pit stops minimum. All races shall be flown with at least two entrants, and not more than four entrants. At contestants where entrants fly preliminary heats to determine finalists, at least three entries shall proceed to the final races. The decision on the number of final entries shall be made by the event director and made in advance before the start of any preliminary heats.

10. It is assumed that the usual sportsmanship of Northwest modelers will prevail in this event. The event director may disqualify any entrant that is not in keeping with the spirit or intent of this racing event.

FL/jmt9/29/85 //Ed:4/15/93//rev2/12/95//rev:mhballot:1/5/14

For a complete copy of the Northwest Sport Race rules (without the annotations above), and for an explanation of how the Northwest control-line rules process works, see the Northwest Rules page.

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This page was upated Feb. 5, 2014