Chapter 6

A carelessly planned project takes three times longer to complete than expected; if carefully planned, it will take only twice as long.
- Golub's law

From the standpoints of simplicity and low cost a rubber-powered design should be considered for a first project. The model should be one that introduces the building process and is rugged enough to withstand repeated attempts to trim the model for a good flight pattern.

6.1 The AMA Cub/Delta Dart Approach

The Delta Dart first appeared in the April 1967 issue of American Modeler magazine. It was designed by AMA's Technical Director, Frank Ehling as a beginner's first model. Sig Manufacturing Company made up the first kits for the 1968 AMA National competition. SIG began marketing the design as the AMA Racer. Ehling designed a smaller version called the AMA Cub. Midwest Model Company sells the design as the Delta Dart. Currently SIG sells the AMA Racer, AMA Cub and a larger version, the Thermal Dart.

All flying surfaces- the wing, horizontal tail and vertical tail, have pointed tips. It is a collection of triangles, defying the rules of best wing outline, but like the bumblebee it flies very well despite the aerodynamics.

Ironically, instead of teaching the beginner the normal practice of covering framework with tissue, the instructions direct the novice to build the framework on the tissue. One can't argue with the success enjoyed by first-time builders. It is interesting to see the number of experienced flyers trying the design from time to time for some fun and relaxation. For more on the AMA Cub/Delta Dart see

6.2 The Wright Stuff Approach

The Science Olympiad/Wright Stuff organization is covered in Chapter 3 at 3.1.5. Here we will discuss briefly the aircraft model design employed in the event.

The model is built to competition requirements as opposed to a specific design. However the design tends to evolve into the appearance of an AMA Pennyplane design, having a stick fuselage and built-up flying surfaces covered with tissue.

The following year 2001 rules are presented only to illustrate the type of model involved in the competition. They are not to be considered official. The criteria for a given year's competition is reviewed annually.

  1. The airplane can only be constructed from balsa wood, paper and glue. (no films or other exotic materials.)
  2. The wingspan can be no more than 50 cm. The wing chord may not exceed 12 cm. The airplane must be a monoplane, no biplanes. Wings may be attached by rubber bands.
  3. The stabilizer span (the width of the tail) must not exceed 35 cm.
  4. A commercial plastic propeller of no more than 20 cm diameter must be used. It must be molded in one piece. When you buy them, they include a metal propeller shaft. This is permitted. You are not allowed to build your own propeller.
  5. The airplane must weigh at least 10 grams without the rubber motor
  6. The rubber band motor must weigh 2 grams or less including lube and O- rings.
  7. Landing gear is required in the High School Event. Wheels must be no more than 1.5 cm diameter.

Related Web site: and click so volunteers needed and click free plan for a typical design plan, and click SO-TSA Volunteer/Assistance Main Page for more information.

6.3 Adult Participation

The AMA and Science Olympiad programs covered above are designed for youthful beginners. This does not mean that adults shouldn't read the instructions, buy a kit and achieve success on their own. There are groups of adults creating their own competitions with models designed to Wright Stuff rules.

Also, beginning adults should consider basic kit designs that are available from many suppliers. SIG and Peck-Polymers are but two examples. See their Web sites at:

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Copyright 2002, Robert S. Munson. All Rights Reserved