During the period from 1977 to 1982, two and four rotor naturally aspirated Stratified Charge Rotary Combustion engines were under development For the U.S. Marine Corps. These engines are described and highlights of work conducted under the government “Advanced Development” contracts are discussed.
The basic direct injected and spark ignited stratified charge technology was defined during 1973-1976 for automotive engine applications. It was then demonstrated that the unthrottled naturally aspirated Rotary could match indirect injected diesel fuel consumption, without regard to fuel cetane or octane rating. This same technology was, scaled from the 60″3/rotor automotive engine module to the 350″3/rotor military engine size.
In addition, parallel company-sponsored research efforts were undertaken to explore growth directions. Tests showed significant thermal efficiency improvement at lean air-fuel ratios. When turbocharged, high exhaust energy recovery of this ported engine provided. Induction airflow sufficient for increased output plus excess for operation at the lean mixture strengths of best combustion efficiency. With additive improvements in mechanical efficiency accruing to the higher BMEP operation the potential for fuel economy in the same range as direct injected diesels was demonstrated.
These lightweight, compact, multi-fuel engines are believed to open new possibilities for lightweight, reliable, highly mobile and agile military fighting vehicles of the future.