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Relevant Rotary Engine developments at Curtiss-Wright over the period 1958-1979 are reviewed. Applicable automotive engine developments, including Stratified Charge, flight test results and future projections are presented. The current 300 HP aircraft engine prototype development status is discussed relative to application of parallel direct injected unthrottled Stratified Charge technology gains which demonstrated automotive diesel engine fuel consumption levels, low emissions and multi-fuel operation in other Rotary engine models.

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.

Results of a 1983 U.S. Navy Study to define stratified charge rotary engine powered shipboard generators from 1000 to 1500 kW output are summarized. The study showed that a 6-rotor version of the 5.8 liter/rotor engine, designed in 1977 for the U.S. Marine Corps as a 4-rotor engine, could effect significant savings in total system weight and size over existing units while offering the advantages of good fuel economy, low vibration and noise inputs and ease of replacement or repair, enhanced by a proposed module approach. U.S. Navy sponsored turbocharging tests of a 1-rotor, 5.8 liter rig engine, conducted in 1984, are discussed as well as relevant background data. In addition, scaling factors are presented.

Curtiss-Wright's rig results to support development of a large Rotary (Wankel-type) direct injected stratified charge multi-fuel Military engine are related to earlier automotive -sized engine data. The comparisons indicate similar thermal efficiency of the larger 350 C.I.D. single rotor rig and the 60 C.I.D. size. However, improved configurations and basic technology advances have been realized during development of the larger module which have not been tested on the smaller engine. Relevant growth studies for General Aviation engines are summarized and test data indicating directions for significant improvements in specific fuel consumption at lean mixture strengths, via turbocharging, are presented and reflected in automotive model Rotary engine projections. System analysis shows sizeable fuel economy gains of naturally aspirated and turbocharged Rotary stratified charge over existing automotive engines.

The paper discusses progress of the Curtiss-Wright Rotating Combustion (RC) Engine series. Results, since 1958, include: over 20,000 test hours, dynamometer evaluation of one to four rotor engines covering a displacement range of 445/1, achievement of over 150 hp and 160 bmep from the basic 60 cu in. size, successful operation with JP-4 fuel, air cooling at high performance levels, elimination of oil from the fuel, completion of 1500 hr cyclic endurance test, and evaluation of a two-rotor vehicular engine. History, data, and background are presented. Engine size, weight, simplicity, and output smoothness are shown to be superior to reciprocating engines. It is concluded that the liquid cooled, gasoline fueled RC engine is ready for application; the potential of advanced versions is also discussed.

The status of the rotating combustion aircraft engine program at Curtiss-Wright as of the fall, 1966, is presented. Related developments which led to present configurations are briefly discussed and likely directions for the future are mentioned. This prior work included cumulative test time of 34,000 hr on one to four-rotor engines covering a displacement range of 445/1; the development of durable, efficient components; feasibility demonstrations of air cooling and heavy fuels operation; and field testing in automobiles, boats, and generating sets. This background leading to the current JP fuel-injected 310 hp engine (RC 2-90) is developed to show that today's RC engine offers propeller driven and rotary wing aircraft a new powerplant approaching the size, weight, and smoothness of the gas turbine at reciprocating engine fuel economy and cost.