Pylon Racing
Dave Lane
WELL, IT IS TIME to start tuning that racing jewel for the 1977 season. I have had some interest expressed in setting up the fuel system for racing.
Let's look at the Q.M. problem first. Keep the centerline of the fuel tank as close to the center of the spray bar of the carburetor as possible. If the tank is too high, the engine will tend to run rich and if the tank is too low, the engine will run lean. Be sure the fuel tank is clean before assembly! Keep in mind that you cannot run pressure in Q.M.!
I use 1/8" nylon tubing for the vent lines and surgical tubing with a "clunk weight" for the fuel pick-up. You need the flexible pick-up line so you won't kill the engine accidentally when the fuel gets low. Remember, you have to land with the engine running. Check the surgical tubing before each weekend of racing to be sure it is still flexible and still on the nylon tubing.
The nylon tubing is easy to shape by using hot water out of the tap. Hold the tubing under the hot water until you have the desired shape and then dip the tubing in cold water. This will "set" the nylon and will hold the new shape for as long as the Q.M. will last.
The fuel pick-up tube should be positioned so that the end of the tube does not quite touch the back of the fuel tank (Fig. 1). Make the nylon pick-up tube long enough to go through the firewall and the fill/vent tubes long enough to go through the fuselage. This eliminates the possibility of kinking the lines. Use surgical tubing from the pick-up tube to the carburetor, again being careful not to kink the flexible line.
You may wonder why I haven't mentioned a filter. I usually filter the fuel before it goes into the tanks. You can use a filter in the fuel pick-up line if you so desire. Use the one that also doubles as the clunk weight.
When you install the tank in the fuselage, be sure that the tank is not wedged against the firewall or sides. The tank should be able to "float." I use pieces of paper towel loosely stuffed around the tank. If the tank is wedged in tightly, the fuel will tend to "suds" and the fuel draw will become erratic. Another trick is to wrap the tank with tape and leave a tab on the end of the tank to facilitate removal. (See Fig. 2.)
Q.M. at the Winternats at Marana Airpark, 35 miles north of Tucson, was hosted by the Tucson RC Club again during the Thanksgiving weekend. The weather was cold, windy and clear—typical weather for the Tucson area in November.
There were 13 entries and eight rounds of competition completed on Friday, November 25th. After the dust had settled, Mike Cook had managed to hang on to first place. Second place was occupied by Jack Stafford, Jack Aycock, Harper Daniell and Tom Prescott. This was the only fly-off of the contest and was held in a 15-knot wind. Tom Prescott cut early in the race and Jack Stafford and Jack Aycock were going at it hot and heavy. Stafford led the entire race and won easily after the 5th lap. After it was all over, Stafford was 2nd, Aycock 3rd, Daniell 4th, Prescott 5th, and John Lockwood finished 6th.
Jack Stafford's Brown-B3 was by far the fastest Q.M. at Marana. It seemed as though he could lap the competition at will, but two flame-outs cost him first place.
The Rossi .15 was the most popular engine in use with one or two Supertigres also being run. Several of the Rossis were being run without any type of extractor or pipe. The Rossis with a pipe, even though they have a slot cut in them, seem to turn better than the Rossis without a pipe.
The Tucson club did a fine job of running the pylon event. The only complaints I heard were that there wasn't enough time between rounds. With each round only consisting of five heats, it only took about 30 minutes per round. If you had to do any repair between rounds, you were just out of luck!
It was unfortunate that another Q.M. contest was held the same weekend in Southern California. This type of contest scheduling doesn't help the Q.M. effort to gain in popularity. Tom Christopher won the event in California.
Dave Lane, 4477 W. 136th St., Hawthorne, CA 90250; (213) 675-3219.
Transcribed from original scans by AI. Minor OCR errors may remain.
