https://ntrs.nasa.gov/search.jsp?R=19800011788 2020-03-21T19:51:36+00:00Z NASA Contractor Report 3260 150 and 300 kW Lightweight Diesel Aircraft Engine Design Study Alex P. Brouwers Teledyne Continental Motors Muskegon, Michigan Prepared for Lewis Research Center under Contract NAS3-20830 N/ /X National Aeronautics and Space Administration Scientific and Technical Information Office 1980 TABLE OF CONTENTS PageNo. 1.0 Summary ...................................................... 1 2.0 Introduction ................................................... 4 2.1 Advantages of the Diesel Engine .................................. 4 2.2 Previous Aircraft Diesel Engines .................................. 5 2.3 Scope of the Project ............................................. 7 2.4 Relative Merit of this Project to the General Field .................... 7 2.5 Significance of the Project ....................................... 7 3.0 Engine Design Study ............................................. 8 3.1 Technology Analysis ............................................ 8 3.1.1 Literature Search ............................................... 8 3.1.2 Definition of the Technology Base ................................. 8 3.1.3 Definition of the Design Approaches ............................... 16 3.1.4 Criteria Attributes ............................................... 17 3.1.5 Ranking Priorities ................................................ 18 3.1.6 Rating of Criteria ............................................... 19 3.1.7 Logic of Ranking ................................................ 19 3.2 Choice of EngineConfiguration and Technologies ................... 27 3.2.1 Initial Elimination of Items from the Flow Chart Figure 3-1 ............. 27 3.2.2 Choice of Engine Configuration ................................... 29 3.2.3 Comparison of 2-Stroke Cycle Operation vs. 4-Stroke Cycle ............ 34 3.2.4 Final Engine Configuration ....................................... 35 3.2.5 Choice of Technologies .......................................... 36 3.3 The 298 kW 6-Cylinder Engine ..................................... 36 3.3.1 Stroke Cycle ................................................... 36 3.3.2 Uncooled Cylinders ............................................. 36 3.3.3 Injection System ................................................ 36 3.3.4 Independent Turbocharger Operation .............................. 36 3.3.5 Synthetic Oil ................................................... 39 iiio°° Page No. 3.3.6 Initial Performance Parameters ................................... 39 3.3.7 Engine Concept Design .......................................... 40 3.3.8 298 kW Engine Operating Data .................................... 47 3.3.9 P-V Diagrams ................................................... 48 313.10 Stress Calculations ............................................. 54 3.3.11 Projection of Fuel Consumption ................................... 58 3.3.12 Energy Balance Turbocharger -- Take-Off .......................... 60 3.3.13 Cooling Requirements ........................................... 61 3.3.14 Anticipated Maximum Surface Temperatures of Engine Components ... 63 3.3.15 Weight of the 298 kW Diesel ...................................... 63 3.3.16 Initial Cost of the 298 kW Diesel ................................... 64 3.3.17 Emissions .... .................................................. 65 3.3.18 Noise ......................................................... 65 3.3.19 Risk Areas Associated with the Selected Design ..................... 66 3.3.20 Proposed Development Program for the 298 kW Diesel Engine ......... 66 3.3.21 Alternate Technologies .......................................... 69 3.3.22 Comparison of the 298 kW Aircraft Diesel and a Comparable Current Gasoline Engine .............................. 70 3.4 The 149 kW 4-Cylinder Engine ..................................... 72 3.4.1 Technologies Applied to the 149 kW Engine ......................... 72 3.4.2 Minimum Cylinder Cooling ....................................... 72 3.4.3 Variable Compression Ratio Piston ................................ 74 3.4.4 Mechanically Driven Centrifugal Blower ............................ 75 3.4.5 Glow Plug Starting Aid in Cylinders ................................ 75 3.4.6 Direct Propeller Drive ............................................ 75 3.4.7 Initial Performance Parameters ................................... 76 3.4.8 Engine Concept Design .......................................... 76 3.4.9 149 kW Engine Operating Data .................................... 87 3.4.10 P-V Diagrams ................................................... 88 3.4.11 Stress Calculations ............................................. 93 3.4.12 Projection of Fuel Consumption ................................... 97 3.4.13 Cooling Requirements ............................................ 97 iv Page No. 3.4.14 Anticipated Maximum Surface Temperatures of Engine Components ... 98 3.4.15 Turboc harger Operation ......................................... 100 3.4.16 Blower Operation ............................................... 100 3.4.17 Weight of the 149 kW Diesel ...................................... 100 3.4.18 Initial Cost of the 149 kW Diesel ................................... 100 3.4.19 Emissions ..................................................... 101 3.4.20 Risk Areas Associated with the Selected Design ..................... 101 3.4.21 Proposed Development Program for the 149 kW Diesel Engine ......... 102 3.4.22 Comparison of the 149 kW Aircraft Diesel and a Comparable Current Gasoline Engine .............................. 105 4.0 Engine/Airframe Integration ...................................... 107 4.1 Engine Installation ............................................... 107 4.1.1 Description of the Layouts ....................................... 107 4.2 Aircraft Configurations .......................................... 114 4.2.1 Twin Engine Airplane ............................................ 114 4.2.2 Single Engine Airplane .......................................... 116 4.3 Aircraft Performance Evaluation ................................... 118 4.3.1 Program Input Data ............................................. 118 4.3.2 Calculation Method ............................................. 122 4.3.3 Results of the Simulation Program ................................. 123 4.4 Operating Cost Estimates ........................................ 124 4.4.1 Airplane Acquisition Cost Estimates ............................... 12q 4.5 Propeller Noise Estimates ........................................ 127 5.0 Conclusions ................................................... 128 6.0 Recommendations .............................................. 130 7.0 List of References .............................................. 131 Append ixes A - Bibliography .............................................. 132 B - Metric Conversion Factors ................................. 143 v 1.0 SUMMARY Energy conservation, uncertainties of fuel supply and limited availability of high octane gasoline, have renewed the interest in the diesel aircraft engine, since its fuel economy is better than any type of aircraft engine currently in production. Aircraft diesel engines have been developed before, notably the Junkers "JUMO," the Napier "NOMAD" and the McCulloch TRAD 4180. Of these, only the Junkers opposed piston, 2-stroke cycle engine ever reached the production stage. The Napier Nomad was a 2-stroke cycle, turbocompounded design. Its complexity and the fact that it invaded the territory of turbine engines probably accounted for its demise. The McCulloch engine came close to flying when the program was terminated for non-technical reasons. New technologies, now under active development, will result in even better fuel economies than can be obtained with current state-of-the-art diesel engines. These technologies also make it possible to develop a powerplant which is more compact and lighter than current gasoline aircraft engines. Two engines were investigated in the study, a 298 kW diesel for a twin engined airplane and a 149 kW diesel for a single engined aircraft. The study consisted of three major phases: 1. Technology Analysis. All in-depth survey of available aviation and automotive sources was conducted to identify new developments which offer potential benefits to an aircraft engine. The technology base includes definition of: A. Existing automotive diesel technology, extrapolated to the expected level in the late 1980's. B. Existing and extrapolated aircraft engine technology. C. On-going diesel aircraft engine developments. These technologies were then evaluated and ranked on the basis of performance and adaptability. Engine Concept Design. The technologies which were chosen as a result of the evaluation and ranking process were applied to the design of the 149 and 298 kW engines. Performance, stress, weight, and cost calculations were made concurrently. Engine/Aircraft Integration Study. The results of Phase 2 were then used in an engine-aircraft integration study to determine the performance improvement of an airplane equipped with diesel engines. The study indicates that the diesel promises to be a superior powerplant for general aviation aircraft. The following tabulation, in which the 298 kW diesel is compared to a comparable gasoline aircraft engine shows a reduction of fuel flow, a smaller package and reduced engine weight; see Table I. TABLE I Diesel vs. Gasoline Engine 4-Cycle