Author: G. Hempel
Edition: Model Aviation - 1987/09
Page Numbers: 72, 156
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Control Line: Speed

Gene Hempel

FLASH!—FLASH! Attention all Jet Speed fliers! A new Dyna-Jet engine will be given away for first place in the Jet Sport Speed event at the Southwest Model Airplane Championships. This festive event will be held in Dallas, TX on September 19–20, 1987.

Jet Sport Speed (Southwest Model Airplane Championships)

Jet Sport Speed is designed for the beginner who would like to build and fly a jet model. The rules for the event are as follows:

  1. The engine must be a stock Dyna-Jet with fins. This includes the valve retainer.
  2. The only modifications allowed to the Dyna-Jet engine are as follows:
  • a. The last three fins on the head may be machined to a diameter .020 in. less than the fin in front of them in order to accept a mounting strap.
  • b. A pressure fitting may be silver-soldered into the jet pipe. You may run the engine either pressure-feed or suction-feed.
  1. No cowling allowed on the engine.
  2. No restrictions on model design (anything goes).
  3. The controls must be mounted externally on the wing and fuselage.
  4. The flying lines must be connected to the model with a scissor-type connector 1-1/2 in. long, equivalent to Pylon brand No. 149 scissor connectors.
  5. The model must be flown on two .018-in. OD solid lines. The length of the lines must be 60 ft. The distance is measured from the center point of the grip portion of the control handle to the centerline of the model.
  6. Fuel formulation shall consist of 80% alcohol and 20% methyl ethyl ketone (MEK). Fuel will be furnished by the contest management.
  7. The model will be timed for seven laps after three laps have been completed in the pylon.
  8. The model, with lines and flying handle, must withstand a pull test of 40 Gs.

Consult the August 1986 issue of this magazine to find out what is necessary to construct a model which would conform to the stated rules. This is a challenge to all the jet fliers to make this contest. For more information concerning the Southwesterns, mail a self-addressed, stamped envelope (SASE) to me at the address given at the end of the column.

1/4-Scale NHRA Drag-Racing Funny Cars

Another hot item related to Speed is the upcoming 1/4-scale NHRA (National Hot Rod Association) drag-racing funny cars. Since Texas is a hotbed of racing activity in the Southwest for full-size racing cars (as well as model cars), I recently had the opportunity to work on some of these wild little machines. The specs are similar to full-size cars and these model cars reach over 100 mph!

Some technical notes concerning these models are as follows:

  • The frame is constructed from aircraft-grade tubular steel, heli-arc welded and with a rigid, built-in roll cage.
  • A beautiful, hand-laid fiberglass body covers the frame. These are sold ready to paint in any racing color.
  • A centrifugal clutch in the drive train permits easy starting of the engine, no spooling, and fast acceleration.
  • Dual inboard rear disc brakes combined with a rear-mounted parachute provide the means for slowing down after that last run from the track.

There are several types of engines used in these cars. The engine used by the manufacturer of the cars in this month's photos is a Zenoah 140 two-stroke with chromed cylinder bore. These engines have plenty of space in the cylinder to experiment with port timing. The engine is coupled to the rear wheels by a fully enclosed, three-stage gearbox. Different gear ratios are available for the rear drive axle.

Participation in these model racing events averages 25 to 30 entrants every weekend at the race track. It's very exciting! For more information, mail a SASE to Discount R/C Hobbies, 605 South Sherman St., Richardson, TX 75081. Their telephone number is (214) 669-3705.

Gene Hempel 301 N. Yale Dr., Garland, TX 75042.

Transcribed from original scans by AI. Minor OCR errors may remain.