The One, Brief Life of the Twin Cat

The aircraft was a modification of a 1950s-era Grumman Super Ag Cat biplane that replaced its single radial engine with two 310 hp Lycoming TIO-540 flat-6 engines.

Jason McDowell

Tuesday, April 02, 2024 at 08:55 AM ET

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A photograph from a company brochure nicely illustrates the unique engine layout of the Twin Cat biplane. [Courtesy: Twin Cat Corporation]

Key Takeaways:

The Twin Cat was an early 1980s Supplemental Type Certificate (STC) modification for the Grumman Super Ag Cat, replacing its single engine with two flat-6 engines to offer improved maintenance and multiengine redundancy.
Its design featured an unconventional twin-engine layout, with engines mounted close together and canted outwards, specifically engineered to minimize asymmetric thrust in case of an engine failure.
The modification claimed significant performance benefits, including shorter takeoff distances, a 2,000-pound increase in maximum takeoff weight, and the ability to take off and climb on a single engine.
Despite impressive development credentials and claimed advantages, only a handful of Twin Cats were reportedly built, and the concept was ultimately not pursued further due to unaddressed issues like a reported lack of rudder trim.

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Aerial application has historically involved creative solutions to address unique challenges. Whether the task at hand is crop spraying, pest control, or fire fighting, a multitude of capabilities are required to do the job safely and efficiently. Accordingly, the aircraft types utilized for these duties have evolved and adapted differently from most other categories of aviation.

The “Twin Cat” of the late 1970s and early ’80s was one such example. A development of the 1950s-era, purpose-built Grumman Super Ag Cat biplane, it replaced the Ag Cat’s single 600 hp Pratt & Whitney R-1340 radial engine with two 310 hp Lycoming TIO-540 flat-6 engines.