Construction articles for John Thompson’s “Tarantula” engine were published in Strictly IC magazine in the 1980’s. The “9-engine” part of the name is not a typo. It is because the engine consists of nine individual Cox .049 1-cylinder model airplane engines geared together in an aluminum crankcase hidden within a plastic Williams Brother Pratt & Whitney R-985 model engine kit.

The nine engines are geared to the propeller shaft and all cylinders fire at the same time. It’s a 9-engine engine. Originally completed in the 1970s, this engine is 12″-long, 18″-wide, and 11″-high.

The engine performed flawlessly and, surprisingly, the heat did not distort the plastic kit during operation. A single carburetor is mounted on a centralized intake manifold in the back, which has nine tubes extending from the manifold to each engine resembling the legs of a spider…thus the name, “Tarantula.” The second photo shows this manifold on the back side of the engine.

A close-up of the intake manifold for the Thompson Tarantula.
A close-up of the intake manifold for the Thompson Tarantula.

Exhibit added: May 1, 2008 - Last modified: January 27, 2023

Presented by The Joe Martin Foundation for Exceptional Craftsmanship