engines is scalable to a 100-seat aircraft. Other uses The Wankel engine is well-suited for devices in which a human operator is in close proximity to the engine, e. g., hand-held devices such as chainsaws. The excellent starting behavior and low mass make the Wankel engine also a good powerplant for portable fire pumps and portable power generators. Small Wankel engines are being found in applications such as go-karts, personal water craft, and auxiliary power units for aircraft. Kawasaki patented mixture-cooled rotary engine (US patent 3991722). Japanese diesel engine manufacturer Yanmar and Dolmar-Sachs of Germany had a rotary-engined chain saw (SAE paper 760642) and outboard boat engines, and the French Outils Wolf, made a lawnmower (Rotondor) powered by a Wankel rotary engine. To save on production costs, the rotor was in a horizontal position and there were no seals on the downside. The simplicity of the rotary engine makes it well-suited for mini, micro, and micro-mini engine designs. The Microelectromechanical systems (MEMS) Rotary Engine Lab at the University of California, Berkeley, has previously undertaken research towards the development of rotary engines of down to 1 mm in diameter, with displacements less than 0.1 cc. Materials include silicon and motive power includes compressed air. The goal of such research was to eventually develop an internal combustion engine with the ability to deliver 100 milliwatts of electrical power; with the engine itself serving as the rotor of the generator, with magnets built into the engine rotor itself. Development of the miniature rotary engine stopped at UC Berkeley at the end of the DARPA contract. In 1976, Road & Track reported that Ingersoll-Rand would develop a Wankel engine with a chamber volume Vk of with a rated power of per rotor. Eventually, 13 units of the proposed engine were built, albeit with a larger displacement, and covered over 90,000 operating hours combined. The engine was made with a chamber volume Vk of , and a power output of per rotor. Both single, and twin-rotor engines were made (producing or respectively). The engines ran on natural gas and had a relatively low engine speed due to the application that they were used for. Deere & Company acquired the Curtiss-Wright rotary division in February 1984, also making large multi-fuel prototypes, some with an 11-liter rotor for large vehicles. The developers attempted to use a stratified charge concept. The technology was transferred to RPI in 1991.