Wheelair IIIA (oz14295)

About this Plan

Wheelair IIIA. Scale model for CO2 power. Twin-boom pusher layout.

Quote: "Built in the Seattle area right after WWII, one of the chief designers is a friend of the author, and was also designer of the Wee Bee, Honey Bee, and Queen Bee aircraft, Ken Coward.

Here is an out-of-the-ordinary model powered by the Brown A-23 CO2 engine. The twin boom pusher arrangement is very protective of the little jewel that is produced by Bill Brown. The engine itself is actually very robust, but it seems a shame to subject it to the abuse of running into walls as is inevitable if a model is flown indoors. Also the Brown will run in either direction, which makes it an admirable powerplant for a pusher design.

There are likely some ghosts on the plan that indicate there were some changes from the original drawings to the final design. These were not the result of modifications required to make the model fly. They were the result of the 'Bane of a Scale Modeler's existence.'

Photographs of the prototype aircraft, obtained after the first model was built, showed it to differ significantly from the promotional three-view used to design the first model. So the model was disassembled, the fuselage, nose gear, engine air inlet, and tail surfaces were rebuilt, and the model was recovered in the correct color scheme.

(It must be admitted that some of the disassembly was accomplished by a high-speed entry into a rosebush, which disclosed the necessity of replacing the wing leading edge with harder wood.)

The wing and tail structure of the model is quite conventional and needs little in the way of building instructions. The wing ribs should be cut out of firm 1/16 sheet balsa. The wing dihedral break is at rib R-2 and the amount of dihedral is shown on the side view. The main landing gear is designed to be a torque arm shock absorbing system and is mounted on the wing's lower rear spar by means of a length of 1/16 diameter aluminum tubing. Use 1/32 diameter, or thinner, piano wire for all landing gear wires.

The tail booms are round in cross-section and can be carved from solid balsa if desired, however, they turned out to be exactly the diameter of common plastic soda straws and I utilized straws on the model in the photos. This doesn't save any time, the end plugs still have to be carved, and saves little weight, but soda straw booms are an interesting structural application.

The fuselage of this model, which includes the engine installation, is the real 'piece de resistance' of this construction article and will be covered in detail.

First off, enough good things cannot be said about Bill Brown's A-23 CO2 engine. It is a thing of beauty, reliable, starts with the first flip, is easily adjustable as far as power output is concerned, is easily fueled, is clean, and is quiet. Actually it makes just enough noise to sound realistic indoors on a small model.

Start the fuselage construction effort by preparing the CO2 engine for installation. Use a round, not a hexagon, shaped pencil to make the loops on the tubing. Be very careful not to get a kink in any of the lines. When bending the loops make sure that the tubing is snuggly up against the pencil as the bends are made. No bends should be attempted with the tubing in free space between supports. When the engine is ready for installation, it will lie directly over the drawing in the side view. There should be no strain on any of the engine components when they are installed in the fuselage structure.

The fuselage sides are cut from 1/32 sheet balsa. The sides below the engine cowl are considerably longer than the airplane side view, and this extra length is shown as a phantom line almost all the way back to the propeller..."

Supplementary file notes

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