X engine

From MedBib.com - Medicine & Nature

A simplified diagram of an X24 engine.

An X engine is a piston engine comprising twinned V-block engines horizontally-opposed to each other. Thus, the cylinders are arranged in four banks, driving a common crankshaft. Viewed head-on, this would appear as an X. X engines were often coupled engines derived from existing powerplants.

This configuration is extremely uncommon, primarily due its weight and complexity as compared to a radial engine. However, it was more compact (per number of cylinders) than a V-engine.

Most examples of X engines are from the World War II era, and were designed for large military aircraft. The majority of these are X-24's based on existing V-12's. The following are examples of this engine type:

• Ford, as an X-8 prototype during the 1920s that led the way to the company's eventual Flathead V-8.^[1][2]
• Daimler Benz DB 604, developed for the Luftwaffe’s Bomber B program. Development suspended.
• Isotta-Fraschini Zeta R.C. 24/60, developed for the Caproni F6 fighter, but never fully completed before Italy’s surrender in 1943.
• Rolls-Royce Vulture, based on two Peregrines and the powerplant of the ill-fated Avro Manchester bomber and the Hawker Tornado fighter.
• Napier Cub, a water cooled X-16 engine of the 1920's, which powered the prototype Blackburn Cubaroo torpedo bomber.
• Honda is said to have experimented with an X-32 engine configuration in the 1960's for their Formula One racing efforts, but abandoned the design as being too complex and unreliable.

References

This article does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unverifiable material may be challenged and removed. (September 2007)