PAA Payload Winner - Free flight gas model. By Herbert Kothe, 68" Wing Span, AIR TRAILS Pictorial, May 1949
Quote: "COMPETITION for the payload type model has been talked about for many years, but nothing was done about it until 1948, when Pan American Airways inaugurated their sponsorship of this event. PAA has opened the field of competition for an airplane which has had to take a back seat in recent years to the contest ship.
Heretofore realistic models have never had a chance in a contest which is predominated by the superpowered high-performance contest jobs of today. Now one can build realistic models with heavier wing loadings and be able to compete. Pan American Airways, by sponsoring the PAA-Load event, is endeavoring to stimulate the development of models that employ some of the same characteristics of commercial aircraft - that is, models that not only fly successfully but also carry a cargo or payload. Rules adopted for the PAA-Load event are such that the design of the model is restricted to a certain degree. The rules state that the model must meet AMA specifications for class B. In other words, the weight must be at least 100 ounces per cubic inch engine displacement and the engine must be no smaller than .20 cubic inches displacement and no larger than .299 cubic inches displacement. In addition to meeting the AMA rules the model must also conform to the requirements that apply only to the PAA-Load model. These rules state that the model shall carry in flight two dummy occupants, composed of a body 3 x 3 x 1in, each occupant weighing 8 ounces.
Except for balance purposes, neither of the occupants shall in any manner be essential to the operation of the model. The model must provide an enclosed compartment for carrying the occupants in upright positions relative to normal flight. Inserting and removing of each occupant must be convenient with the model completely assembled, except for the operation of the doors or hatches. Occupants may touch each other if seated side by side but there must be at least 2in between them if seated tandem, one behind the other. Visibility must be provided each occupant to the front and to both sides through a windshield and windows (at least one inch high, unobstructed except for normal structural framework and the heads of the occupants.
It can be seen by reading these rules that the design of a model that would conform to them would definitely be restricted. Probably the design problem that resulted in the most deliberation was: what would be the optimum wing loading to use? Obviously if the wing loading were very high the glide ratio would be reduced, although if the wing loading were low, drag would increase and consequently climb would be sacrificed. After giving much thought to this problem I decided to use a wing of approximately 700 square inches projected area which would give a wing loading of approximately 7 ounces per 100 square inches of area.
After the problem of wing loading had been solved, the type of model to be designed had to be determined. I chose to keep the model within the limits of conventionality so that it could be constructed easily and with a minimum of time. I had only one month before the Nationals to build and test the plane, so I wanted as simple a model as possible, yet efficient and not overly timeconsuming to construct.
Preliminary flight tests with the PAA-Loader proved that it was going to be a good competitor. With only a slight shifting of the dummy occupants the model attained an amazingly flat and long glide. About 3 degrees of downthrust and a good Torpedo 29 was all that was required for the model to have a climb that would rival some of the pylon jobs I have seen. ROG flights were made without the slightest difficulty even though the model had a 16-ounce cargo to carry.
Now a few words of advice on the construction of the PAA-Loader. As I have said, the model has been designed as simply as I believe possible, so no one should have difficulty building it. Lay out the two sides of the fuselage, building one on top of the other, so precision between the sides can be obtained. Build the door on the right side of the fuselage only, which would be the side next to the plan. A diagonal brace is inserted in place of the door on the left..."
Update 11/02/2018: Replaced this plan with a clearer copy (scanned from fullsize) thanks to dfritzke.
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