Breeze (oz13863)

About this Plan

Breeze. Indoor rubber duration model.

Quote: "FULL-SIZE PLANS for the very successful and relatively simple USA design. For low ceiling indoor flying. Breeze, by Larry Renger.

EARLY IN 1961 Wally Miller devised the 'Easy B' class model for the Wilmington Model Airplane Club, in the USA. At the time, it was felt that a reasonably simple, small but high performance indoor rubber model, was needed for beginner and expert alike. Beginners tend to cringe at the thought of bracing, rolled tube bodies, built up, microfilm covered props, and flimsy structure. On the other hand, 'experts' needed an event as easy to build for as hand-launched glider. The set of rules used at WIMAC is :

1. All components must be solid.
2. All outlines of flying surfaces must be straight lines.
3. No bracing of any kind.
4. Prop must be sheet wood.
5. Maximum wing span 18 in. Maximum wing chord 3 in. Area not to exceed 54 sq in.
6. Maximum tailplane area 50 per cent wing area.

Despite the fact that these rules would seem to harshly limit performance, on September 14th, 1962, the Breeze made a flight of 10 minutes, 38.6 seconds in the Wilmington Recreation Hall. The flight set a Category 1 Senior US National Record. The National Record is in the same class with 100 sq in. area, 'full house' microfilm models.

Construction Hints: It is assumed that the Breeze is not a raw beginners model, only a few of the finer points of construction will be discussed.

A basic requirement for any serious indoor builder is a good scale. Accurate 'eyeball' choice of wood is about as unlikely as cutting spars with a pair of scissors. To duplicate a model it is necessary to match wood sizes and weights. A simple, reasonably good balance is advisable and one can easily build one, using a piece of a double edge razor resting in a small block of solid material.

Cutting spars properly requires a good straight edge. Most hardware stores carry racks of aluminium edging, tubing and strips. A 6 ft strip of 1 in x 4 in, cut into 1 ft, 2 ft, and 3 ft sections will fill most of your modelling needs. Before use be sure to remove all burrs, because a small cut can go through the whole sheet.

Much of the success of the Breeze is due to the propeller. Despite common practice of using 9 to 10 in diameter propellers with flat or randomly curved blades, the Breeze prop has 11 in diameter and 25 in pitch with true helically warped blades. Construction of this prop is more difficult than the normal curved ones only in that it is necessary to make a forming block.

Rather than carve out a prop-block, it has been found to be faster to construct a block from 1/16 sheet balsa. A 5-1/2 x 1-1/2 in rectangular and 5-1/2 x 2-1/8 in triangular pieces of wood are glued together then planked as shown. The planking should be 1/16 x 3/16 strips. It is best not to use a white glue as there is some possibility of the soaked blades sticking to the block.

After the blades have been sanded and cut out (in that order to prevent 'windows' at the edges), they are soaked in boiling water for five minutes, wrapped to the block with wet strengthened tissue strips and baked at 250 deg for 15 minutes. The spar and shaft are assembled in the normal manner and then glued to the blades using the block for a jig to assure perfect alignment.

Production of a high performance indoor model requires a balance between light weight and structural strength. It proved necessary to discard many parts which were overweight or too weak while building the Breeze. The construction of Breeze I saw discard of one completed and three partial motorsticks, two sets of spars and one complete wing, a double bearing and one complete prop. Breeze II was much easier to build, but due to experimentation several parts proved to be even too light. "

Direct submission to Outerzone.

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