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dwbebens -> RE: Okay Gurus - Question on engine placement (2/19/2008 2:17:46 PM)
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happypappy;
From your location, I assume you will be flying with the Florida Club 40 group.
Here are the current North-Central Florida Club 40 rules that I just pulled off the Tri-County RC Club (Dunnellon Fl) website.
http://tricountyrcclub.homestead.com/
What is Club40 Pylon Racing?
Club40 Pylon Racing uses "low wing" sport aircraft and .40 size "sport" engines. Everyone is limited to using one designated aircraft and engine combination. This makes all race planes about equal and results in "flying skill" being the dominant factor in winning. The relative low cost of equipment adds to the appeal of this event.
The course is made up of two pylons spaced 600 feet apart. This makes for a lap of approximately 1/4 mile long. A race or heat is usually 10 laps. The entire race covers approximately 2.5 miles in length. Speeds are in the range of 60-65 mph.
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“CLUB 40 PYLON RACE” – RULES (v.1.01.2008)
The aircraft shall be the Sky Raider Mach II ARF manufactured by World Models Mfg. Co., Ltd. and distributed in the USA by AirBorne Models. Parts are available from this link.
http://www.airborne-models.com/html/productdetails.asp?ProductID=16
The airframe must remain essentially stock in shape and dimensions. The fuselage side ‘cheek’ extensions have been found to be a weak area; a single cross-brace is allowed and suggested, but it shall be no larger than 1/2” wide or thick. It is also suggested to reinforce the landing gear block. Any brand hardware such as clevises, pushrods, and horns, etc. may be used. Any fuel tank may be used as long as only muffler pressure is used (no pen-bladder high pressure tanks). The three wheels supplied in the kit must be used. The engine mount may also be changed, however the engine must remain upright. The kit-supplied canopy is mandatory and it shall be located roughly as shown on the box. Any model that has raced prior to July 1st of this year that has a slightly different canopy shape, size, or location is considered ‘Grandfathered’ and shall be allowed to continue racing, but if repairs are necessary, it is expected that it will be brought up to current standards. A spinner must be used; any brand may be used as long as it has a diameter of 2” ~ 2-1/2”. No prop nuts or spinner-nuts are allowed. Any prop may be used. All control surfaces must be functional. It is suggested that ‘standard’ servos be used, however there will be no mandatory internal inspections.
Two engines are authorized.
The original stock OS .40LA will continue to be allowed. The supplied OS muffler must be used; however the baffle may be removed.
Effective 1 January 2008, the alternate engine is the Super Tigre GS-40 (ST stock number SUPG012). The "Quiet Muffler" as shown on the ST Web Site, with no modifications, as well as the supplied carb must also be used. No tuned pipes on either engine.
Host clubs will provide the fuel which will be 15% Cool Power or equivalent. Host-supplied fuel must be used and all fueling shall be done at the designated fueling station. It is requested that there be no other fuel jugs in the pit area.
Concerning the engines: at this time, no procedures are established to check for ‘stock engines’ such as engine tear-downs, engine RPM checks, or establishing some form of claim rules. We are all here to race and to have fun -- and hopefully we are all gentlemen of honor. Please act accordingly.
Trim and colors may be changed as desired, however large numbers indicating the frequency* channel you are racing on will be displayed as follows: The numbers will be a minimum of 10” high x 6” wide; they will be located on the underside of the right wing and orientated vertically; that is the first number would be out near the wing tip with the top of the number towards the tip. The second number will be below it and between it and the fuselage. The purpose is to allow the pylon spotters to easily identify your model as it is banked during the turn. “Line” thickness will be proportional to the overall size; a minimum of one inch - even bolder preferred.
*With the increased usage of the 2.4 GHz spectrum, the “race number” displayed may be your old R/C channel number with the addition of a third suffix letter of the same size or better yet, a new number above 60 approved by the Race Committed to prevent duplicates.
It has been suggested that all right wing undersides should be standardized white with bold black numerals. The race committee does not wish to mandate this. However, it is strongly suggested that if a new model or wing is acquired, or if repairs are made requiring recovering, make that wing panel a solid light color with the numbers being a bold contrasting dark color (or visa-versa). This is a suggestion; NOT a rule.
Ideally, each pilot will have a dedicated R/C channel for his, and only his, use at all races. The Pilot/Frequency list will be available to assist interested modelers to select their channel. In the event a new racer shows up at his first race with a radio on an established racer’s channel, race personnel will accommodate him into the matrix. New racers will be encouraged to switch to an unused channel, if available, by their next race.
End of rules
With the OS 40 LA, a larger prop works best. Believe it or not, some of the best times are to be had with a 10-7 or 11-7 APC prop! Make sure you don't go off the line too lean with these big props. I'm not familiar with the ST GS 40 though. I'm sure you will get some good advice from the TX group about props for the ST engine.
Just put the engine in the recommended location and the plane will fly just fine.
Keep the CG near 3" aft of the LE. Set-up your elevator so the plane "sweeps" through the turn at full up elevator deflection. A turn rate that is too fast will overly slow the plane. Use high rates for take-off/landing and low rates for racing. Another handy hint is to have 1/2 as much down elevator as up elevator throw. This will help you be smoother around the course. I find that a good amount of expo in the elevator helps smooth the entry and exit of the turns.
It does say in the rules "any prop". Unless you know how to work props, it's best not to fool with them. You are more likely to go slower, not faster. Besides, APC makes EXCELLENT props. Since the SR Mk II is so draggy and has such a large flat front end, the larger diameter props (10"+) have proven to be best.
Doug Bebensee
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