Baby Biplane R-8 (oz15431)

About this Plan

Baby Biplane (AKA Model R-8). Simple free flight biplane model, for rubber power.

Direct submission to Outerzone.

Update 29/7/2024: Added article, thanks to Pit.

Quote: "Building A Baby Biplane. A Simple Plane That Will Provide Worlds of Fun and Valuable Information for Beginner or Expert. By Robert C Hare.

EVERY model builder has, one or more times in his career, felt a strong desire to construct a biplane of a given type which would perform as well as any monoplane in the same category. However few young men have achieved this goal, for model biplanes are tricky craft and what may appear to be 'the' ship on paper more often than not fails to fly at all.

Biplane R-8 described here will be welcomed by novice builders possessing a 'biplane complex' while experienced builders will find many hours of first-class flights available to them during production of other types. It was during the latter case that the R-8 was conceived by the writer.

This little biplane was built with the goal in mind to surpass in every way the performance of a conventional monoplane ROG used in coaching beginners. All of which takes in a lot of territory when one considers that in a biplane we find two centers of aerodynamic force in the cellule which must balance to insure normal flight. In addition to providing enough lift to support the machine in the air, the resultant force of the R-8 had to be sufficiently great to overcome the considerable structural drag common to this type of machine.

Construction: Begin the R-8 by constructing the fuselage and its components. Select a piece of medium weight balsa 8 inches long with a 5/32 x 3/32 inch cross section, sand it smooth and curve one end as shown in the drawing. This will be the lower side and the front as well. Notch the rear end at the bottom by cutting out a piece 1/16 x 1/4 inches and into this channel fit the 1/16 inch square balsa extension. Its length is 2 inches.

Next make the thrust bearing from a piece of thin aluminum, tin, or brass and drill a small shaft hole near one end. Bend the sheet to the shape shown in the plans so that the hole will allow a clearance of 3/32 inch between the shaft and the motor stick. Cement the bearing securely in its proper place ; binding with thread is not necessary.

At the rear end of the stick, cement a rear hook securely in place after the short prong has been sunk into the wood to add strength. The tail skid is made of split bamboo 1/32 inch in diameter cut to the length shown in the plans. Sharpen one end and jab the skid into the motor stick a distance of about 3/32 inch and cement the joint well.

When this has dried the two landing gear struts may he made and attached. Each strut is cut to length from 1/32 inch diameter bamboo. Sharpen one end of each strut and with a pin make two small holes about 3/32 inch deep at each lower corner of the stick. These holes should be 1 1/8 inches from the front and on such an angle as to provide a tread of 2 1/2 inches. Cement these joints thoroughly but be sure to true and align the legs before the cement hardens.

In building the two axel bearings, the novice will find a sample of finer model work. These bearings are made of thin aluminum sheet cut to the outline shown in axel drawing B. The hole should he 3/64 inch in diameter. To attach these bearings set them on the outsides of the landing gear struts and bend their upper sides around the struts as shown in BB. This can be accomplished with the aid of fine nose pliers. The preliminary fit need only he tight enough to prevent the bearings coming off..."

Update 2/8/2024: Fixed the scaling of this plan to 9 inch wingspan.

Supplementary file notes

Article.

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