Northrop Gamma (oz16156)

About this Plan

Northrop Gamma 'Sky Chief'. Control line scale model. Wingspan 32 in.

Quote: "Traced and corrected Oct 1982, by Dick Gleason."

Direct submission to Outerzone.

Update 19/7/2025: Added article, thanks to Pit.

Quote: "Like it? Then build this 32-inch exact scale control-line version of the famous Northrop Gamma. Power with any .19 to .49 engine. Sky Chief, by Walter A Musciano.

BORED with the unrealistic appearance of the present free-flight gas jobs? Tired of control-line 'speed demons'? The author was and decided to combine scale appearance, good looks and realistic flying into his next project. The task was not an easy one because most good looking, low wing models have so little wing area they fly much too fast for real enjoyment - and safety. After examining scores of old time designs, the Sky Chief was selected because it fulfilled every requirement. The author's model has, to date, placed first in two beauty contests.

The Sky Chief was designed and built by John Northrop in 1930 for the late Frank M Hawks who was superintendent of the Aviation Division of the Texas Company. The craft was appropriately named 'Texaco Sky Chief', although the manufacturer called it the Northrop Gamma. As a result of its careful streamlining, many inter-city speed records were established and the Sky Chief, with Hawks at the controls, became one of the hottest airplanes of that era.

A twin row, fourteen cylinder Wright R-1510 engine of 700 horsepower drove the ship at over 200 mph - but the landing speed was a mere 42 mph! This alone reflects the sound aerodynamic design incorporated in all Northrop aircraft. The range of the Sky Chief was over 2,500 miles.

Commander Hawks was not alone in his praise of the fine ship. Lincoln Ellsworth, Jacqueline Cochran, Howard Hughes and Jack Frye are a few of the notables who recognized the Gamma's superior performance. The Douglas A-25 and SBD-1 and the now obsolete Northrop A-17 were evolved from this design. In fact, a few Gammas are still flying!

The model was designed to combine lightness with strength. This was achieved by using the backbone-former planking method of construction for the fuselage, and heavy spar and ribs plus sheet covering for the wing. Pants and tail surfaces are built up from soft balsa because they are not subject to stress.

Full size plans are a must and may be obtained by sending 50 cents to the Mechanix Illustrated Plans Service, Fawcett Building, Greenwich, Connecticut. Order Plan No. 386. The plans show installation of the Ohlsson 23 engine but any power plant from .19 to .49 cubic inch displacement can be used. Naturally, the nose must be altered accordingly. When using a larger engine, it also will be necessary to either move the battery position back slightly or else obtain the correct center of gravity position (1/2 in back from the leading edge of the center section) by adding a little lead to the front bulkhead.

Start construction by cutting the fuselage backbone from 1/2 in sheet hard stock, then glue the engine mounts in place. The distance between the mounts is governed by the size of the engine used.

While the cement is drying, cut out the bulkheads and formers and attach. Follow by cementing the wing root leading and trailing edges and ribs in place after the landing gear is secure..."

Supplementary file notes

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