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Engine dynamometer testing was conducted on a production automotive engine. Untreated exhaust emissions were measured over a range of hydrogen/natural gas fuel mixtures and equivalence ratios (Φ). The most important finding was that, with retarded ignition, extremely low raw NOx emissions can be attained at the same time as high brake thermal efficiency. With a 30% hydrogen mixture and Φ = 0.65, the effect of spark timing on engine efficiency is almost negligible over approximately 15° of crankshaft rotation. For an engine load of ∼400 kPa, brake thermal efficiency remained at 30%. NOx emissions can be kept below 0.05 g/kWh for bmeps up to 500 kPa and rpms above 1700, with low hydrocarbons and minimal effect on fuel economy.

John Deere Technologies International (JDTI) developed several different Stratified Charge Rotary Engines (SCREs), using 3 module sizes, .66,1.7,and 5.8 liters/rotor, over a period of eight years starting in February 1984. This paper summarizes: the principal technical features, performance results, supporting research efforts and current status of the 60kW (80HP) to 840kW (1125 HP) engine series, updating and referencing key related JDTI publications. All of these engines are Wankel-type, direct injected and turbocharged, featuring extremely wide range fuel capability and economy competitive with comparably rated Diesels. In addition to reviewing development of the SCREs, the paper briefly discusses test of a naturally aspirated, natural gas carbureted spin-off of the largest engine series.

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.

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.

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.

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.

Development progress of the unthrottled direct injected Stratified Charge Rotary Combustion Engine Program at the Curtiss-Wright Corporation is updated since the 1974 status reported in SAE Paper 741206. Emphasis during this period has been on performance improvements in the automotive road load range. Results are given for a number of variations tested since that date, including engine performance with gasoline and other fuels. The baseline configuration has been further improved and new designs which have improved fuel consumption and reduced hydrocarbon emissions are described in the paper. These data are presented showing steady-state SFC equal or better than representative automotive diesel engines; comparable untreated emission data are presented with HC emissions reduced to a representative band level of automotive carbureted engines and with relatively low CO and NOx.

Development progress of the direct injected Stratified Charge Rotary engine program at Curtiss-Wright is detailed. Basic configurations are described and compared to both reciprocating stratified charge engines and the carbureted Rotary engine. Data and theoretical analyses are presented for progressive developments from initial feasibility testing in 1962 through current configurations now on test. It is concluded that the Stratified Charge Rotary Engine research efforts to date have demonstrated potential for an efficient, lightweight, compact, economic powerplant capable of broad range operations justifying further research efforts.

This paper summarizes the highlights of developments of the rotating combustion (RC) engine at Curtiss-Wright Corp. in each of several principal areas; speculates on remaining directions, both within and without the framework of previous explorations; and briefly describes germane technical features of the engines used in commercial applications of other licensees. At the same time an attempt has been made to span gaps left by previous papers or publications and to expand material considered proprietary earlier. Design features, testing, and ramifications of the RC1-60 rig engine are examined in detail. The application of the fundamentals and principles of the RC engine to automotive, air-craft, and small, air-cooled engines is also described.

The paper covers exploratory development of the Rotating Combustion (RC) engine spark ignited stratified charge versions since 1966. Configuration improvements resulting in increased power and reduced fuel consumption are described and test results cited. Exhaust emissions are presented, with and without a catalytic converter, and compared with carbureted RC engine results as well as limited diesel engine data. It is concluded that the technical bases for an efficient, lightweight, economic, low-emission powerplant capable of broad range operation have been demonstrated. Weight and displacement parametric curves are presented for one family of advanced higher speed engines.

The Curtiss-Wright RC2-60 engine exhaust emissions were measured, with and without an exhaust reactor, under steady-state conditions at the University of Michigan and in a vehicle operated on the simulated California cycle at an independent facility. The reactor successfully reduced the emission levels in both cases. Data are presented for the steady-state trends of engine emissions as a function of engine performance variables; trends are generally similar to those of conventional gasoline engines. The particular effectiveness of an exhaust reactor with the RC engine is attributed to port characteristics and higher exhaust gas temperatures unique to this engine together with new reactor design features. Theoretical considerations and future investigations are 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.

As a means toward further improving the Curtiss-Wright rotary combustion (RC) engine series, test work during the past year has concentrated on the two-rotor 200 hp class liquid cooled engine, application testing of this engine in vehicles, boats, and engine generator sets, and evaluation of basic component and engine design studies covering aircooled, fuel injected, and spark ignited engines with heavy fuels for aircraft and other applications. Field tests have established acceptable automotive, marine, and power generation performance levels. In addition, operation on heavy fuels and aircooling at high-performance levels has been demonstrated, with attendant basic engine improvements. This paper reviews the recent development and test program at Curtiss-Wright aimed at bringing the RC engines closer toward production engine status.

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.