CF6 High Bypass Turbofan Cutaway
This article details the process by which McDonnell Douglas selected the CF6 to power the DC-10. It was made possible through a document donation by William Lewis.
McDonnell Douglas DC-10 Engine Trade Studies
How the General Electric CF6 Was Selected
Compiled by Kimble D. McCutcheon
Published 1 Apr 2028
CF6 High Bypass Turbofan Cutaway |
The Pratt & Whitney JT9D was certified in May 1969 and entered service in January 1970, powering the Boeing 747. Initially, nearly all JT9D engines were used by Boeing in the 747's manufacture, so McDonnell Douglas needed another turbofan for its DC-10. The General Electric (GE) CF6 was a civilian turbofan derived from the GE TF-39, which was originally designed for the Lockheed C-5. The CF6 entered service during 1971 in the McDonnell Douglas DC-10. The Rolls-Royce RB211 was the first production three-spool engine. It was certified and entered service in 1972, powering the Lockheed L-1011. This article details the process by which McDonnell Douglas selected the CF6 to power the DC-10. It was made possible through a document donation by William Lewis. |
• Extensive Technical and Corporate Resources
• Organized Progressive Outlook
• Desire and Ability to Support Joint Douglas and Airline Development
• Technical Excellence in Thermodynamics, Internal Aerodynamics, Metallurgical Applications, and Turbine Cooling Techniques
1962 = Basic Design Conceived
1964 = Cycle First Demonstrated (GE 1/6)
1965 = Full Scale Experience Initiated (TF-39)
1968 = CF6 Evolution• Superior Fuel Consumption
• Highly Developed by Initial Service
• Designed for On-Condition Maintenance
• Built-In Growth
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| CF6/36-6 Longitudinal Cross Section |
| Takeoff Thrust (lb), SL, Static | Cruise Thrust (lb), 35,000 ft, M = 0.85 | |
|---|---|---|
| Uninstalled, No Losses | 40,000 | 9,100 |
| Short Reference Exhaust System | 39,500 | 8,920 |
| DC-10 Acoustically Treated Inlet & Exhaust System | 39,400 | 8,910 |
| DC-10 Acoustically Treated Inlet & Exhaust System and Scrubbing Drag | 36,800 | 8,930 |
| Flat Rated to 84°F | Flat Rated to STD +18°F |
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| CF6 Engine Development | CF6/TR39 Comparison |
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| TF39 Testing | Typical SFC Development History |
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| TF39 Flying Testbed | Air Start Results |
| General Electric | Rolls-Royce |
| Stall-Free Operation Demonstrated with 25:1 Pressure Ratio | Full-Scale 25:1 Pressure Ratio, 3-Spool Machine, Yet to be Tested |
Proven GE Variable Stator Experience• 7 Million Hours |
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| Bypass Ratio Effect on SFC | Guaranteed SFC |
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| Scale Fan Rotor | CF6 Demonstrator Fan Test Results |
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| F6 Fan Performance | Combustor Cross Section |
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| Combustor Temperature Spread | GE annular Combustor Experience |
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| Combustor Design | Smoke Reduction |
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| Turbine Nozzle Cooling Evolution | Cooled Turbine Blade Evolution |
• Leading edge film cooling introduced into service in 1965 on CF700
• Over 200,000 hrs of service with GE film cooled turbine blades and/or vanes:CF700, CJ610, J84, T64, T58, J79-10, J79-17, J79-19, TF 39, plus four advanced military engines with extremely high turbine inlet temperatures.
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| Turbine Inlet Temperature Evolution | Leading Edge Cooling Requirement |
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| Turbine Blade Metal Temperature Comparison, CF6-6 and RB 211-22 | Flyover Noise Spectra, Takeoff Thrust |
| GE | JT3D-3B | |
|---|---|---|
| Takeoff – SL, Mo = 0.25 | ||
| Primary | 1,231 fps | 1,560 fps |
| Fan | 937 fps | 1,060 fps |
| Approach – SL, Mo = 0.25, 45% Takeoff | ||
| Primary | 722 fps | 980 fps |
| Fan | 703 fps | 870 fps |
| SPL ~ Vj8 | ||
• Zero Stage Core
• Flare Core Compressor
• Larger Diameter Fan
• Core Supercharge
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| Engine Development Status | Zero Stage |
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| Compressor Flare | Larger Diameter Fan |
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| Core Supercharge | Core Supercharge |
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| Rolls-Royce Growth Geometry | First Step Growth Changes |
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| GE CF6 Engine Growth (no dimensional changes) | R-R RB 211 Engine Growth (no dimensional changes) |
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| GE/R-R Growth Comparison | Growth Engine Development |
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| GE CF6 Compressor Growth | Temperature and Gas Generator Output |
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| Cruise Turbine Temperature Change with Growth | Turbine Metal versus Gas Temperatures |
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| Growth Material Capability and Growth Step II Requirements | GE CF6 Growth Summary |
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