The General Electric TF39 was a high-bypass turbofan engine that was developed to power the Lockheed C-5 Galaxy. The TF39 was the first high-power, high-bypass jet engine developed. The TF39 was further developed into the CF6 series of engines, and formed the basis of the LM2500 and LM6000 marine and industrial gas turbine. On September 7, 2017, the last active C-5A powered with TF39 engines made its final flight to Davis-Monthan Air Force Base for retirement.[1][2] The TF39 was effectively retired, and all remaining active C-5 Galaxys are now powered by F138 (General Electric CF6-80C2) engines.
TF39
A TF39 on a C-5 Galaxy at ILA (Internationale LuftfahrtAusstellung) in Berlin, 2008
The United States Air Force opened the "CX-X Program" in 1964, intending to produce a next-generation strategic airlifter. Of the several airframe and engine proposals returned for consideration, Lockheed's aircraft and General Electric's engine were selected for the new design in 1965.
The high-bypass turbofan was a huge leap in engine performance, offering a thrust of 43,000 pounds, while improving fuel efficiency by about 25%.[3] The TF39 had an 8:1 bypass ratio, a 25:1 compressor pressure ratio, and a 2,500 °F (1,370 °C) turbine temperature made possible by advanced forced-air cooling. The first engine went for testing in 1965. Between 1968 and 1971, 463 TF39-1 and -1A engines were produced and delivered to power the C-5A fleet.
Design
TF39s on a C-5 Galaxy, from the rear
The TF39 was a revolutionary 1960s engine rated from 41,000 to 43,000 lbf (191 to 205 kN) of thrust. It introduced use of a large by-pass ratio which, together with advances in core technology, contributed to a significant improvement in fuel efficiency over engines available at the time.
The engine included features developed from previous GE engines:
Snubbered first stage fan blades (snubbers, or mid-span shrouds, had been introduced by GE on the YJ93 first stage compressor blades[5])
Today, a conventional turbofan featuring a T-staged fan would have an overhung fan rotor (without any inlet guide vanes), followed by one or more T-stages supercharging the core stream alone.[6] The name T-staged fan is derived from the overall appearance of the LP compressor when the side elevation is shown diagrammatically.
GE took a different approach with their first high bypass ratio turbofan, the TF39. It is a unique, very complex design.[7] The T-stage, which supercharges the core stream, is located ahead of the main fan rotor. The T-stage itself comprises an overhung mini-rotor followed by a set of outlet guide vanes; the main fan rotor is located immediately behind these OGVs. Outboard of the T-stage rotor are the main inlet guide vanes, which only affect the bypass stream. The T-stage rotor extends to about half the main rotor stage annulus[5][8] and runs in a tip shroud. The main fan stage has a mid-span platform/flow splitter which separates the single-stage outer annulus from the two-stage inner annulus.[8] These two stages mainly supercharge the 16-stage high-pressure compressor.[9] However, a fair proportion of the air entering the T-stage is bled off into the bypass duct, there being two annular passages leading to the bypass duct. The nominal bypass ratio of 8:1 refers to the ratio of total bypass mass flow to HP compressor entry mass flow.
The rotor blades are snubbered. 'Snubbers' are protuberances that stick out at right angles to the fan aerofoil at mid[5] to 2/3 span.[10] At speed, the snubbers on adjacent fan blades butt-up against each other to prevent blade failures due to flutter.[10] They, together with the second-stage inlet guide vanes in the outer half of the duct, are visible when looking into the engine intake.[11][12]
The high-bypass ratio of 8:1 for the TF-39 had its origins in the lift-fan technology demonstrated by GE in the XV-5 Vertifan aircraft.[4] This aircraft had two X353-5 engines, each consisting of a 62.5-inch-diameter[13] lift-fan driven by a gas generator (J85). The bpr in VTOL operation was 12.3.[14] This tip-turbine driven lift-fan concept was turned 90 degrees and developed as an 80-inch-diameter "cruise fan" demonstrator, driven by a J79 gas generator.[4] For the CX-X program GE demonstrated a half-scale engine, the GE1/6, with 15,830 lb thrust and an sfc of 0.336.[15] This was developed into the TF39 with a 97 in diameter fan.[8]
A Boeing B-52E (Serial Number 57-0119) testing a TF39 on the right inboard engine pod. The TF39 has more than double the thrust of the twin Pratt & Whitney J57s that were originally in that spot.
^Smith, Hanna (8 September 2017). "And then there were none, the final C-5A departs Westover ARB for retirement > Westover Air Reserve Base > Article Display".
^Balik, Roland (12 April 2016). "An era of Dover-built TF39 engines throttles down". Air Mobility Command. Retrieved 9 February 2023.
^General Electric - CF6 history 2009-01-27 at the Wayback Machine
^ abcde"seven decades of progress" General Electric, ISBN0-8168-8355-6, Aero Publishers Inc. p.152
^ abc"Gas Turbine Technology Evolution: A Designer's Perspective" Bernard L. Koff, Journal of Propulsion and Power, Vol.20 No. 4, July–August 2004, p.591
^ abc"Flight Manual USAF Series C5A and C5B Airplanes", TO 1C-5A-1, Lockheed Martin Corporation
^"Aviation Week" 16 August 1965, shown as Figure 35 in "The History Of The Rolls-Royce RB211 Turbofan Engine", ISBN978-1-872922-48-5, The Rolls-Royce Heritage Trust
^ ab"Flutter and Resonant Vibration Characteristics of Engine Blades" A.V. Srinivasan, 97-GT-533, ASME, p.8
^"Aerodynamic characteristics of a Large-Scale Model with a High Disk Loading Lift Fan Mounted in the Fuselage" Aoyagi, Hickey and deSavigny, NASA TN D-775
^"Jet Propulsion for Aerospace Applications" Second Edition, Hesse and Mumford, Pitman Publishing Corporation, 1964, Table 11.1
^"The Development of Jet and Turbine Engines", 4th edition, Bill Gunston, ISBN0 7509 4477 3, p. 192
^Gas Turbine Engines. Aviation Week & Space Technology Source Book 2009. p. 119
Gunston, Bill (2006). World Encyclopedia of Aero Engines, 5th Edition. Phoenix Mill, Gloucestershire, England, UK: Sutton Publishing Limited. ISBN0-7509-4479-X.
External links
Wikimedia Commons has media related to General Electric TF39.
April 29, 2023
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The General Electric TF39 was a high bypass turbofan engine that was developed to power the Lockheed C 5 Galaxy The TF39 was the first high power high bypass jet engine developed The TF39 was further developed into the CF6 series of engines and formed the basis of the LM2500 and LM6000 marine and industrial gas turbine On September 7 2017 the last active C 5A powered with TF39 engines made its final flight to Davis Monthan Air Force Base for retirement 1 2 The TF39 was effectively retired and all remaining active C 5 Galaxys are now powered by F138 General Electric CF6 80C2 engines TF39A TF39 on a C 5 Galaxy at ILA Internationale LuftfahrtAusstellung in Berlin 2008Type High bypass turbofanNational origin United StatesManufacturer GE AviationFirst run 1964Major applications Lockheed C 5 GalaxyNumber built 463Developed into General Electric CF6 General Electric LM2500 Contents 1 Development 2 Design 3 Applications 4 Specifications TF39 1C 4 1 General characteristics 4 2 Components 4 3 Performance 5 See also 6 References 7 External linksDevelopment EditThe United States Air Force opened the CX X Program in 1964 intending to produce a next generation strategic airlifter Of the several airframe and engine proposals returned for consideration Lockheed s aircraft and General Electric s engine were selected for the new design in 1965 The high bypass turbofan was a huge leap in engine performance offering a thrust of 43 000 pounds while improving fuel efficiency by about 25 3 The TF39 had an 8 1 bypass ratio a 25 1 compressor pressure ratio and a 2 500 F 1 370 C turbine temperature made possible by advanced forced air cooling The first engine went for testing in 1965 Between 1968 and 1971 463 TF39 1 and 1A engines were produced and delivered to power the C 5A fleet Design Edit TF39s on a C 5 Galaxy from the rear The TF39 was a revolutionary 1960s engine rated from 41 000 to 43 000 lbf 191 to 205 kN of thrust It introduced use of a large by pass ratio which together with advances in core technology contributed to a significant improvement in fuel efficiency over engines available at the time The engine included features developed from previous GE engines Variable stator vanes used in the J79 CJ805 4 Turbine cooling techniques advanced from the J93 used in the XB 70 4 Cascade type thrust reverser from the CJ805 4 Snubbered first stage fan blades snubbers or mid span shrouds had been introduced by GE on the YJ93 first stage compressor blades 5 Today a conventional turbofan featuring a T staged fan would have an overhung fan rotor without any inlet guide vanes followed by one or more T stages supercharging the core stream alone 6 The name T staged fan is derived from the overall appearance of the LP compressor when the side elevation is shown diagrammatically GE took a different approach with their first high bypass ratio turbofan the TF39 It is a unique very complex design 7 The T stage which supercharges the core stream is located ahead of the main fan rotor The T stage itself comprises an overhung mini rotor followed by a set of outlet guide vanes the main fan rotor is located immediately behind these OGVs Outboard of the T stage rotor are the main inlet guide vanes which only affect the bypass stream The T stage rotor extends to about half the main rotor stage annulus 5 8 and runs in a tip shroud The main fan stage has a mid span platform flow splitter which separates the single stage outer annulus from the two stage inner annulus 8 These two stages mainly supercharge the 16 stage high pressure compressor 9 However a fair proportion of the air entering the T stage is bled off into the bypass duct there being two annular passages leading to the bypass duct The nominal bypass ratio of 8 1 refers to the ratio of total bypass mass flow to HP compressor entry mass flow The rotor blades are snubbered Snubbers are protuberances that stick out at right angles to the fan aerofoil at mid 5 to 2 3 span 10 At speed the snubbers on adjacent fan blades butt up against each other to prevent blade failures due to flutter 10 They together with the second stage inlet guide vanes in the outer half of the duct are visible when looking into the engine intake 11 12 The high bypass ratio of 8 1 for the TF 39 had its origins in the lift fan technology demonstrated by GE in the XV 5 Vertifan aircraft 4 This aircraft had two X353 5 engines each consisting of a 62 5 inch diameter 13 lift fan driven by a gas generator J85 The bpr in VTOL operation was 12 3 14 This tip turbine driven lift fan concept was turned 90 degrees and developed as an 80 inch diameter cruise fan demonstrator driven by a J79 gas generator 4 For the CX X program GE demonstrated a half scale engine the GE1 6 with 15 830 lb thrust and an sfc of 0 336 15 This was developed into the TF39 with a 97 in diameter fan 8 Applications EditLockheed C 5A B C GalaxySpecifications TF39 1C Edit A Boeing B 52E Serial Number 57 0119 testing a TF39 on the right inboard engine pod The TF39 has more than double the thrust of the twin Pratt amp Whitney J57s that were originally in that spot Data from 16 General characteristics Type Turbofan Length 312 in 792 cm Diameter 97 in 246 cm Dry weight 8000 lb 3630 kg Components Compressor Axial 2 stage fan 16 stage high pressure compressor Combustors Annular Turbine Axial 2 stage high pressure turbine 6 stage low pressure turbinePerformance Maximum thrust 43 300 lbf 193 kN Overall pressure ratio 25 1 Fuel consumption 3 7646 lb s 1 7075 kg s Specific fuel consumption 0 313 lb lbf h 8 9 g kN s Thrust to weight ratio 5 4See also EditRelated development General Electric CF6 General Electric LM2500Comparable engines Pratt amp Whitney JT9D Progress D 18T Rolls Royce RB211Related lists List of aircraft enginesReferences Edit Smith Hanna 8 September 2017 And then there were none the final C 5A departs Westover ARB for retirement gt Westover Air Reserve Base gt Article Display Balik Roland 12 April 2016 An era of Dover built TF39 engines throttles down Air Mobility Command Retrieved 9 February 2023 General Electric CF6 history Archived 2009 01 27 at the Wayback Machine a b c d e seven decades of progress General Electric ISBN 0 8168 8355 6 Aero Publishers Inc p 152 a b c Gas Turbine Technology Evolution A Designer s Perspective Bernard L Koff Journal of Propulsion and Power Vol 20 No 4 July August 2004 p 591 br715 Google Search Airliners net Aviation Forums a b c Flight Manual USAF Series C5A and C5B Airplanes TO 1C 5A 1 Lockheed Martin Corporation Aviation Week 16 August 1965 shown as Figure 35 in The History Of The Rolls Royce RB211 Turbofan Engine ISBN 978 1 872922 48 5 The Rolls Royce Heritage Trust a b Flutter and Resonant Vibration Characteristics of Engine Blades A V Srinivasan 97 GT 533 ASME p 8 TF39 front view planes cz TF39 running airliners net Aerodynamic characteristics of a Large Scale Model with a High Disk Loading Lift Fan Mounted in the Fuselage Aoyagi Hickey and deSavigny NASA TN D 775 Jet Propulsion for Aerospace Applications Second Edition Hesse and Mumford Pitman Publishing Corporation 1964 Table 11 1 The Development of Jet and Turbine Engines 4th edition Bill Gunston ISBN 0 7509 4477 3 p 192 Gas Turbine Engines Aviation Week amp Space Technology Source Book 2009 p 119 Gunston Bill 2006 World Encyclopedia of Aero Engines 5th Edition Phoenix Mill Gloucestershire England UK Sutton Publishing Limited ISBN 0 7509 4479 X External links Edit Wikimedia Commons has media related to General Electric TF39 General Electric TF39 website Retrieved from https en wikipedia org w index php title General Electric TF39 amp oldid 1143210855, wikipedia, wiki, book, books, library,
