North American O-47 (oz540)

About this Plan

North American O-47. Control line scale model. WWII Observation Plane.

Quote: "Forerunner of the modern reconnaissance aircraft, this 1930s design becomes a C/L scale model. North American O-47, by Richard A Hall.

It only takes one quick glance at the side profile of this aircraft to enable you to identify it as the 0-47. a very popular observation plane of the 1930s. Various adjectives, used by aviation buffs and historians to describe it, inevitability pertain to its obese appearance. The deep belly of the aircraft. provided the cameraman-observer with a space to perform his duties with excellent vertical and oblique viewing. This middle crewman could also raise his seat to an upper location between the pilot and the rear gunner. The observer's top position was equipped with enough instruments and controls to qualify it as an auxiliary pilot's position.

The 1060 horsepower Wright Cyclone engine pulled the three man crew along at a top speed of over 220 miles per hour. Gross weight was about 8000 pounds for this lightly armed plane. One .30 caliber fixed machine gun in the right wing and one .30 caliber flexible machine gun in the rear seat, on a ring mount, served as defensive armament.

Over 230 versions of the 0-47A and 0-47B were built during the late 1930s. Virtually every Air National Guard unit in the United States had one, or more, of the 0.47s in their service. It was said to have good flight characteristics.

It served its purpose well, however the 0.47 became obsolete during the early days of World War II. The 'observation types' of modern times were becoming high speed reconnaissance aircraft.

The model featured here was based on plane number 21 of the 116th Observation Squadron out of Gray Field, Fort Lewis, Washington. The Army Air Corps used the letter O with a bar through it to avoid having it mistaken for the number zero. To the uninformed, the modified O looked like a malformed B, or the Greek letter Theta.

A few pointers should be noted before you grab your cutting tools. Formers F5T, F6T and F7 require some portions to he cut away after the fuselage has been planked. When cutting out these formers, make partial cuts at the dotted lines to facilitate removal of the unwanted sections later.

You may wish to add stiffener pieces, of optional size, across F2B and F3 for additional strength, and as an aid in alignment. Make sure that these optional pieces do not interfere with other components.

Former F4B is to be installed during the normal building operation but it is to be removed after planking has been completed. This will make the planking conform to the proper fuselage contours. Also its removal, in whole or in part, will allow an unobstructed view through the lower windows.

Don't lose those small 'nuisance pieces' which are parts of formers F5T and F7. They are located outboard of the crutch pieces and must be in place prior to planking.

Construction: Wing construction: Cut out the balsa wing ribs and the plywood wing spars as shown. The leading and trailing edges are cut from 1/2 in sheet or laminated from two 1/4 in sheets. The wing tips are cut to shape in planform from 3/4 in sheet or laminated sheets. That thickness is required based on the depth of rib W10 plus the 1/16 wing skins. The tips are contoured later. Accurately notch the trailing edges at the rib locations... "

Update 5/2/2023: Added article, thanks to George.

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