American twins,Brit triple spool engines?
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There are four prime factors to consider when comparing engines.
1. Purchase price.
2. Fuel burn.
3. Weight: lower weight means lower Air Traffic Control (ATC) fees if maximum Take-Off Weight (MTOW) is reduced or more revenue from a higher payload.
4. Maintenance cost.
Fuel Burn Comparisons.
ICAO Engine Emissions Databank.
Document Categories | Human and Environmental Issues | Safety Regulation
A380 with EA or RR engines.
http://www.caa.co.uk/docs/702/9EA001_10122010.pdf
EA 7270 - Rated Output - 332.39 kns.
Take-off - 2.637 kg/s.
Climb-out - 2.169 kg/s.
Approach - 0.711 kg/s.
Idle - 0.234 kg/s.
http://www.caa.co.uk/docs/702/9RR047_10122010.pdf
RR T972-84 - Rated Output - 345.9 kns.
Take-off - 2.69 kg/s.
Climb-out - 2.230 kg/s.
Approach - 0.750 kg/s.
Idle - 0.270 kg/s.
A380-800 Payload/Range charts.http://www.airbus.com/fileadmin/medi...0_20101101.pdf
GP 7200 engine - maximum structural payload range - 9625 nm.
Trent 900 engine - maximum structural payload range - 9525 nm.
B747-400 with GE or Pratt or RR engines.
http://www.caa.co.uk/docs/702/3GE057_01102004.pdf
CF6-80C2B5F- Rated Output - 272.53 kns.
Take-off - 2.685 kg/s.
Climb-out - 2.162 kg/s.
Approach - 0.697 kg/s.
Idle - 0.206 kg/s.
http://www.caa.co.uk/docs/702/1PW043_01102004.pdf
Pratt 4060 - Rated Output - 266.9 kns.
Take-off - 2.647 kg/s.
Climb-out - 2.085 kg/s.
Approach - 0.703 kg/s.
Idle - 0.213 kg/s.
http://www.caa.co.uk/docs/702/1RR011_01102004.pdf
RB211-524H - Rated Output - 264.4 kns.
Take-off - 2.73 kg/s.
Climb-out - 2.17 kg/s.
Approach - 0.71 kg/s.
Idle - 0.26 kg/s.
B777-200ER with GE or Pratt or RR.
http://www.caa.co.uk/docs/702/9GE128_10122010.pdf
GE-94B - Rated Output - 431 kns.
Take-off - 3.513 kg/s.
Climb-out - 2.831kg/s.
Approach - 0.876 kg/s.
Idle - 0.285 kg/s.
http://www.caa.co.uk/docs/702/10PW099_10122010.pdf
Pratt 4090- Rated Output - 408 kns.
Take-off - 3.926 kg/s.
Climb-out - 2.996 kg/s.
Approach - 0.979 kg/s.
Idle - 0.338 kg/s.
http://www.caa.co.uk/docs/702/5RR040_01102004.pdf
RR T895 - Rated Output - 413 kns.
Take-off - 4.03 kg/s.
Climb-out - 3.19 kg/s.
Approach - 1.05 kg/s.
Idle - 0.33 kg/s.
A330-200/300 with GE or Pratt or RR.
http://www.caa.co.uk/docs/702/4GE081_01102004.pdf
GE CF6-80E1A4 - Rated Output - 297 kns.
Take-off - 2.904 kg/s.
Climb-out - 2.337 kg/s.
Approach - 0.744kg/s.
Idle - 0.227kg/s.
http://www.caa.co.uk/docs/702/9PW092_10122010.pdf
Pratt 4164 - Rated Output - 287 kns.
Take-off - 2.721 kg/s.
Climb-out - 2.239 kg/s.
Approach - 0.775 kg/s.
Idle - 0.243 kg/s.
http://www.caa.co.uk/docs/702/3RR030_01102004.pdf
RR T772 - Rated Output - 316 kns.
Take-off - 3.2 kg/s.
Climb-out - 2.58 kg/s.
Approach - 0.85 kg/s.
Idle - 0.28 kg/s.
B767-300ER with with GE or Pratt or RR.
http://www.caa.co.uk/docs/702/8GE101_04102007.pdf
CF6-80C2B8F - Rated Output - 267 kns.
Take-off - 2.583 kg/s.
Climb-out - 2.106 kg/s.
Approach - 0.685 kg/s.
Idle - 0.205 kg/s.
http://www.caa.co.uk/docs/702/1PW043_01102004.pdf
Pratt 4060 - Rated Output - 266.9 kns.
Take-off - 2.647 kg/s.
Climb-out - 2.085 kg/s.
Approach - 0.703 kg/s.
Idle - 0.213 kg/s.
http://www.caa.co.uk/docs/702/4RR037_01102004.pdf
RB211-524H-T - Rated Output - 264 kns.
Take-off - 2.81 kg/s.
Climb-out - 2.22 kg/s.
Approach - 0.77 kg/s.
Idle - 0.26 kg/s.
http://theaviationspecialist.com/350...sion_table.gif
Note: The GE has a higher cruise thrust than the Trent, but has a lower SFC than the Trent.
GE90-115B
Cruise Thrust - 19,000 lbs. - 84.6 kns. - Cruise SFC. - 0.530 lb/lbth.
Trent 970
Cruise Thrust - 12,700 lbs. - 56.5 kns. - Cruise SFC - 0.561 lb/lbth.
http://theaviationspecialist.com/777...s_dmission.gif
GE90-110B1L
Cruise Thrust - 19,000 lbs. - 84.6 kns. - Cruise SFC. - 0.530 lb/lbth.
Trent 553
Cruise Thrust - 10,700 lbs. - 47.6 kns. - Cruise SFC. - 0.568 lb/lbth.
For the 777 with the GE90, the sea level SFC is 0.324 lb/lbth.
For the 777 with the Trent 800, the sea level SFC is 0.35 lb/lbth.
GE90 SFC (SLS) 8.30 mg/N-s. (cruise)
Trent 882 SFC (SLS) 15.66 mg/N-s. (cruise)
Airbus Payload / Range graphs.http://www.airbus.com/fileadmin/medi...A330_Jan11.pdf
A330-200.
Trent 700 - 9,100nm
PW4000 - 9,200 nm
CF6-80E1 - 9,450nm
( Source for Data required )
A CF6-80 A330 burns 4,700kgs./hour and a Trent 700 closer to 5,000kgs./hour during cruise.
Range Comparisons.
Airbus graphs, with 175t MZFW and 233t TOW:
@ Max structural P/L/MTOW PW4000 - 3,700 n.mls, RR - 3,700 n.mls, GE 90 - 3,750 n.mls.
@MTOW/Max tankage PW4000 - 5,500 n.mls, RR - 5,500 n.mls, GE90 - 5,550 n.mls.
@ Max tankage/zero P/L PW4000 - 6,500 n.mls, RR - 6,500 n.mls, GE90 - 6,600 n.mls.
B777-200ER GE/RR range comparisons.http://www.boeing.com/commercial/sta...f/777_perf.pdf
The GE90-94B has a fuel consumption of 284.8 lbs/seat for a 3000 nautical mile trip while the RR Trent 895 consumes.......... 291.7 lbs/seat for the same distance.
So the Trent 895 burns 6.9 lbs more of fuel than the GE90-94B for each seat every 3000 nautical miles.
With a seat configuration of 300 seats, that equals 2070 lbs or just over a ton more fuel for each 3000nm.
EASA - European Aviation Safety Agency
Engine Weight Comparisons.
EASA - European Aviation Safety Agency
GE: CF6-80E1
Dry Weight: 5,091.62 kgs. (11,225 lbs).
Includes all basic engine accessories and optional equipment as listed in the manufacturer’s engine specs.
EASA - European Aviation Safety Agency
RR: T700 series.
Dry Weight: 6,160 kgs. (13,580 lbs).
(Not including fluids and Nacelle EBU)
EASA - European Aviation Safety Agency
A330-200 O.E.W. weights for each applicable engine http://www.airbus.com/fileadmin/medi...A330_Jan11.pdf
GE powered O.E.W. - 119,831kgs.
RR powered O.E.W. - 119,931kgs.
Engines applicable to the A330-300http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/3c27fd7504a36b648625760e0046cb5a/$FILE/E36NE.pdf
PW 4168 weighs 12,900 lbs.- 5,863 kgs.
Weight of basic engine includes all essential accessories, but excludes starter, exhaust nozzle, and power source for the ignition system.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/d69e8a472455be9286257495006282e5/$FILE/E39NE.pdf
RR Trent 772B-60 dry powerplant weighs 14,360 lbs.- 6,527 kgs.
Engines applicable to the B747-400http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/a54a5cdbed477da18625753c004dd282/$FILE/E24NE.pdf
PW 4062 weighs 9,420 lbs. - 4,273 kgs.
Weight of basic engine includes all essential accessories, but excludes starter, exhaust nozzle, and power source for the ignition system.
http://rgl.faa.gov/Regulatory_and_Guidance_library/rgMakeModel.nsf/0/706579a7e83efab48625727b00751aff/$FILE/E13NE.pdf
CF6-80C2B5F weighs 9,790 lbs. - 4,441 kgs.
Weight includes basic engine accessories & optional equipment as listed in the engine manufacturer's specifications, including condition monitoring instrumentation sensors.
http://www.caa.co.uk/docs/1419/SRG_PRO_1048%20iss11.pdf
RB211-524H2-T-19 weighs 12,573 lbs. - 5,703 kgs.
Dry powerplant weight less intake, intake systems, cowl doors and cowl door support structure.
Engines applicable to the B767-300ERhttp://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/a54a5cdbed477da18625753c004dd282/$FILE/E24NE.pdf
PW 4056 weighs 9420 lbs. - 4,273 kgs.
Weight of basic engine includes all essential accessories, but excludes starter, exhaust nozzle, and power source for the ignition system.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/b015c4c8fa2760a18625765c0053b800/$FILE/E13NE.pdf
CF6-80C2B2 weighs 9670 lbs.- 4,395 kgs.
Weight includes basic engine accessories & optional equipment as listed in the manufacturer's engine specifications, including condition monitoring instrumentation sensors.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/78635932a4cb7e7b862572a70057e006/$FILE/E30NE.pdf
RB211-524H-T-36 weighs 12,540 lbs.- 5,700 kgs.
Dry powerplant weight less intake, intake systems, cowl doors, and cowl door support structure.
Engines applicable to the B757-200 / -300http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/4e1d135907e0ce8686256df1005b1233/$FILE/E17NE.pdf
PW 2043 weighs 7,300 lbs. - 3,318kgs.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/1aaba05dd1012e30862574950062f87e/$FILE/E12EU.pdf
RB211-535E4-B-37 weighs 7,603 lbs. - 3,456 kgs.
//www.airbus.com/fileadmin/medi...h_data/AC/Airbus_AC_A330_Jan11.pdf
Twin spool engines have a more stable airflow pattern since the airflow is being compressed all the way to the last stage of the High Pressure Compressor (HPC) before it enters the diffuser section.
This makes the engine less surge prone in comparison to a three spool design. In a three spool engine, there is a sudden interruption (slowing down) of the airflow in the void between the Intermediate Compressor (IP) and the HP Compressor. When the compressed air leaves the last stage of blades of the IP compressor no more compression takes place until the first stage of the HP compressor blades. This airflow interruption between the two compressors in this uncompressed void makes the engine more surge prone.
The distance between the High Pressure Turbine (HPT) and the Intermediate Pressure Turbine (IPT) also hurts the triple spool's efficency. This distance is required to locate the disks around an extra pair of bearings.The hot gas flowing at a high subsonic speed in this void requires a lot of cooling air to be introduced which results in a considerable airflow loss that could be used for turning another turbine disk which would mean a lower fuel burn. But adding another turbine disk would increase the weight of the engine even more.
In a 3-spool engine, there is quite a bit of extra fuel burn due to the fan being oversped and the turbine powering it spinning below its optimal mach number.
Twin spool engines, (GE or Pratt) have less heat to dissipate than three spool (Rolls Royce) engines.
Three spool engines operate at a higher oil temperature when compared to twin spool engines and the oil distribution is much more complex in three spool engines.
This more complex oil distribution has given RR problems over the years, some call it oil hiding.
They have had to combat oil system problems with the RB211 / L1011; Trent 500 / A340-500/600’s; Trent 700 / A330 and Trent 900 / A380.
Oil Temperature comparisons.
RB211 Series 335'
Trent 700 374'
Trent 800 375'
Trent 900 385'
Trent 1000 365'
CF6-50 320'
CF6-80C2 320'
PW4000 350'
GE90 270'
Internal engine cooling airflow is less complex in a twin spool engine than in a three spool engine.
For this reason triple spool engines emit more smoke during start-up.
Twin spools engines (non contrarotating) have lower gyroscopic moments than triple spool engines, resulting in less side loading of the pod/strut.
Twin spools light off and accelerate faster than three spools.
Compare the slow spool-up time of a RR Trent compared to a GE or Pratt engine in the following link.
Most fighter aicraft engines use a twin spool design for faster throttle response.
Twin spool turbofans have the basic two spool configuration where both the fan and LP turbine (i.e. LP spool) are mounted on a second (LP) shaft, running concentrically with the HP spool (i.e. HP compressor driven by HP turbine). Twin spool engines have lower maunfacturing costs due to a lower parts count than three spool engines. Twin spools are less expensive to overhaul due to the fact that they have only two concentric drive shafts and support bearings.
Rolls-Royce chose a three spool configuration for their large civil turbofans, where the Intermediate Pressure (IP) compressor is mounted on a separate (IP) drive shaft, running concentrically with the LP and HP drive shafts, and is driven by a separate IP Turbine. However, three spool engines are more labor intensive to both build and maintain.
The Rolls Royce single stage High Pressure Turbine (HPT) is at a disadvantage to the competition due to the turbine blades being 30% heavier since they are shrouded at their tips. These heavier blades result in a longer time to reach optimum rotational speed for the HPT with it's coupled HP compressor. Shrouded blades decrease airflow leakage past the turbine blade tips but the unshrouded blades in GE and Pratt & Whitney engines are lighter which promotes faster engine acceleration. In twin spool engines manufactured by GE and Pratt, turbine blade tip airflow loss is reduced and controlled with a design known as Active Clearance Control (ACC) which also improves fuel efficency and lowers emissions. This clearance control design uses an ACC valve which captures cool ambient by pass airflow and routes this air to pipes with exit holes directed at the exterior surface of the turbine casing surrounding the turbine. This airflow reduces the thermal expansion of the turbine case and maintains the critical clearance between the turbine case and the blade tips. In other words, it shrinks the diameter of the turbine case and also allows it to expand when required.
Since three spool engines use three concentric shafts and more support bearings are than are required in twin spool engines. A three spool engine requires three compressors, a low pressure compressor, an intermediate compressor and a high pressure compressor, a high pressure turbine, an intermediate pressure turbine and a low pressure turbine. Twin spool engines have just two compressors, a low pressure and a high pressure compressor, a low pressure turbine and a high pressure turbine.
The RR three spool is more difficult and more labor intensive to manufacture because of the nature of the concentricity of the three drive shafts, support struts/bearings and the fact that is has three distinct compression and turbine stages.
Three spool engines are more labor intensive to balance and are more prone to vibration than twin spool engines.
An Oxford University/Rolls Study from 4/9/02 - 9/30/03 document notes that 10% or more of RR engines failed the final passing out test due to imbalance.
Eleven Trent 500 production engines failed pass-off testing due to abnormal vibrations. This indicates that there was a systemic vibration problem.
A higher rejection rate due to vibration is also detected when the engines are overhauled at the RR appointed agents than twin spool engines during overhaul.
1. Purchase price.
2. Fuel burn.
3. Weight: lower weight means lower Air Traffic Control (ATC) fees if maximum Take-Off Weight (MTOW) is reduced or more revenue from a higher payload.
4. Maintenance cost.
Fuel Burn Comparisons.
ICAO Engine Emissions Databank.
Document Categories | Human and Environmental Issues | Safety Regulation
A380 with EA or RR engines.
http://www.caa.co.uk/docs/702/9EA001_10122010.pdf
EA 7270 - Rated Output - 332.39 kns.
Take-off - 2.637 kg/s.
Climb-out - 2.169 kg/s.
Approach - 0.711 kg/s.
Idle - 0.234 kg/s.
http://www.caa.co.uk/docs/702/9RR047_10122010.pdf
RR T972-84 - Rated Output - 345.9 kns.
Take-off - 2.69 kg/s.
Climb-out - 2.230 kg/s.
Approach - 0.750 kg/s.
Idle - 0.270 kg/s.
A380-800 Payload/Range charts.http://www.airbus.com/fileadmin/medi...0_20101101.pdf
GP 7200 engine - maximum structural payload range - 9625 nm.
Trent 900 engine - maximum structural payload range - 9525 nm.
B747-400 with GE or Pratt or RR engines.
http://www.caa.co.uk/docs/702/3GE057_01102004.pdf
CF6-80C2B5F- Rated Output - 272.53 kns.
Take-off - 2.685 kg/s.
Climb-out - 2.162 kg/s.
Approach - 0.697 kg/s.
Idle - 0.206 kg/s.
http://www.caa.co.uk/docs/702/1PW043_01102004.pdf
Pratt 4060 - Rated Output - 266.9 kns.
Take-off - 2.647 kg/s.
Climb-out - 2.085 kg/s.
Approach - 0.703 kg/s.
Idle - 0.213 kg/s.
http://www.caa.co.uk/docs/702/1RR011_01102004.pdf
RB211-524H - Rated Output - 264.4 kns.
Take-off - 2.73 kg/s.
Climb-out - 2.17 kg/s.
Approach - 0.71 kg/s.
Idle - 0.26 kg/s.
B777-200ER with GE or Pratt or RR.
http://www.caa.co.uk/docs/702/9GE128_10122010.pdf
GE-94B - Rated Output - 431 kns.
Take-off - 3.513 kg/s.
Climb-out - 2.831kg/s.
Approach - 0.876 kg/s.
Idle - 0.285 kg/s.
http://www.caa.co.uk/docs/702/10PW099_10122010.pdf
Pratt 4090- Rated Output - 408 kns.
Take-off - 3.926 kg/s.
Climb-out - 2.996 kg/s.
Approach - 0.979 kg/s.
Idle - 0.338 kg/s.
http://www.caa.co.uk/docs/702/5RR040_01102004.pdf
RR T895 - Rated Output - 413 kns.
Take-off - 4.03 kg/s.
Climb-out - 3.19 kg/s.
Approach - 1.05 kg/s.
Idle - 0.33 kg/s.
A330-200/300 with GE or Pratt or RR.
http://www.caa.co.uk/docs/702/4GE081_01102004.pdf
GE CF6-80E1A4 - Rated Output - 297 kns.
Take-off - 2.904 kg/s.
Climb-out - 2.337 kg/s.
Approach - 0.744kg/s.
Idle - 0.227kg/s.
http://www.caa.co.uk/docs/702/9PW092_10122010.pdf
Pratt 4164 - Rated Output - 287 kns.
Take-off - 2.721 kg/s.
Climb-out - 2.239 kg/s.
Approach - 0.775 kg/s.
Idle - 0.243 kg/s.
http://www.caa.co.uk/docs/702/3RR030_01102004.pdf
RR T772 - Rated Output - 316 kns.
Take-off - 3.2 kg/s.
Climb-out - 2.58 kg/s.
Approach - 0.85 kg/s.
Idle - 0.28 kg/s.
B767-300ER with with GE or Pratt or RR.
http://www.caa.co.uk/docs/702/8GE101_04102007.pdf
CF6-80C2B8F - Rated Output - 267 kns.
Take-off - 2.583 kg/s.
Climb-out - 2.106 kg/s.
Approach - 0.685 kg/s.
Idle - 0.205 kg/s.
http://www.caa.co.uk/docs/702/1PW043_01102004.pdf
Pratt 4060 - Rated Output - 266.9 kns.
Take-off - 2.647 kg/s.
Climb-out - 2.085 kg/s.
Approach - 0.703 kg/s.
Idle - 0.213 kg/s.
http://www.caa.co.uk/docs/702/4RR037_01102004.pdf
RB211-524H-T - Rated Output - 264 kns.
Take-off - 2.81 kg/s.
Climb-out - 2.22 kg/s.
Approach - 0.77 kg/s.
Idle - 0.26 kg/s.
http://theaviationspecialist.com/350...sion_table.gif
Note: The GE has a higher cruise thrust than the Trent, but has a lower SFC than the Trent.
GE90-115B
Cruise Thrust - 19,000 lbs. - 84.6 kns. - Cruise SFC. - 0.530 lb/lbth.
Trent 970
Cruise Thrust - 12,700 lbs. - 56.5 kns. - Cruise SFC - 0.561 lb/lbth.
http://theaviationspecialist.com/777...s_dmission.gif
GE90-110B1L
Cruise Thrust - 19,000 lbs. - 84.6 kns. - Cruise SFC. - 0.530 lb/lbth.
Trent 553
Cruise Thrust - 10,700 lbs. - 47.6 kns. - Cruise SFC. - 0.568 lb/lbth.
For the 777 with the GE90, the sea level SFC is 0.324 lb/lbth.
For the 777 with the Trent 800, the sea level SFC is 0.35 lb/lbth.
GE90 SFC (SLS) 8.30 mg/N-s. (cruise)
Trent 882 SFC (SLS) 15.66 mg/N-s. (cruise)
Airbus Payload / Range graphs.http://www.airbus.com/fileadmin/medi...A330_Jan11.pdf
A330-200.
Trent 700 - 9,100nm
PW4000 - 9,200 nm
CF6-80E1 - 9,450nm
( Source for Data required )
A CF6-80 A330 burns 4,700kgs./hour and a Trent 700 closer to 5,000kgs./hour during cruise.
Range Comparisons.
Airbus graphs, with 175t MZFW and 233t TOW:
@ Max structural P/L/MTOW PW4000 - 3,700 n.mls, RR - 3,700 n.mls, GE 90 - 3,750 n.mls.
@MTOW/Max tankage PW4000 - 5,500 n.mls, RR - 5,500 n.mls, GE90 - 5,550 n.mls.
@ Max tankage/zero P/L PW4000 - 6,500 n.mls, RR - 6,500 n.mls, GE90 - 6,600 n.mls.
B777-200ER GE/RR range comparisons.http://www.boeing.com/commercial/sta...f/777_perf.pdf
The GE90-94B has a fuel consumption of 284.8 lbs/seat for a 3000 nautical mile trip while the RR Trent 895 consumes.......... 291.7 lbs/seat for the same distance.
So the Trent 895 burns 6.9 lbs more of fuel than the GE90-94B for each seat every 3000 nautical miles.
With a seat configuration of 300 seats, that equals 2070 lbs or just over a ton more fuel for each 3000nm.
EASA - European Aviation Safety Agency
Engine Weight Comparisons.
EASA - European Aviation Safety Agency
GE: CF6-80E1
Dry Weight: 5,091.62 kgs. (11,225 lbs).
Includes all basic engine accessories and optional equipment as listed in the manufacturer’s engine specs.
EASA - European Aviation Safety Agency
RR: T700 series.
Dry Weight: 6,160 kgs. (13,580 lbs).
(Not including fluids and Nacelle EBU)
EASA - European Aviation Safety Agency
A330-200 O.E.W. weights for each applicable engine http://www.airbus.com/fileadmin/medi...A330_Jan11.pdf
GE powered O.E.W. - 119,831kgs.
RR powered O.E.W. - 119,931kgs.
Engines applicable to the A330-300http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/3c27fd7504a36b648625760e0046cb5a/$FILE/E36NE.pdf
PW 4168 weighs 12,900 lbs.- 5,863 kgs.
Weight of basic engine includes all essential accessories, but excludes starter, exhaust nozzle, and power source for the ignition system.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/d69e8a472455be9286257495006282e5/$FILE/E39NE.pdf
RR Trent 772B-60 dry powerplant weighs 14,360 lbs.- 6,527 kgs.
Engines applicable to the B747-400http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/a54a5cdbed477da18625753c004dd282/$FILE/E24NE.pdf
PW 4062 weighs 9,420 lbs. - 4,273 kgs.
Weight of basic engine includes all essential accessories, but excludes starter, exhaust nozzle, and power source for the ignition system.
http://rgl.faa.gov/Regulatory_and_Guidance_library/rgMakeModel.nsf/0/706579a7e83efab48625727b00751aff/$FILE/E13NE.pdf
CF6-80C2B5F weighs 9,790 lbs. - 4,441 kgs.
Weight includes basic engine accessories & optional equipment as listed in the engine manufacturer's specifications, including condition monitoring instrumentation sensors.
http://www.caa.co.uk/docs/1419/SRG_PRO_1048%20iss11.pdf
RB211-524H2-T-19 weighs 12,573 lbs. - 5,703 kgs.
Dry powerplant weight less intake, intake systems, cowl doors and cowl door support structure.
Engines applicable to the B767-300ERhttp://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/a54a5cdbed477da18625753c004dd282/$FILE/E24NE.pdf
PW 4056 weighs 9420 lbs. - 4,273 kgs.
Weight of basic engine includes all essential accessories, but excludes starter, exhaust nozzle, and power source for the ignition system.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/b015c4c8fa2760a18625765c0053b800/$FILE/E13NE.pdf
CF6-80C2B2 weighs 9670 lbs.- 4,395 kgs.
Weight includes basic engine accessories & optional equipment as listed in the manufacturer's engine specifications, including condition monitoring instrumentation sensors.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/78635932a4cb7e7b862572a70057e006/$FILE/E30NE.pdf
RB211-524H-T-36 weighs 12,540 lbs.- 5,700 kgs.
Dry powerplant weight less intake, intake systems, cowl doors, and cowl door support structure.
Engines applicable to the B757-200 / -300http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/4e1d135907e0ce8686256df1005b1233/$FILE/E17NE.pdf
PW 2043 weighs 7,300 lbs. - 3,318kgs.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/1aaba05dd1012e30862574950062f87e/$FILE/E12EU.pdf
RB211-535E4-B-37 weighs 7,603 lbs. - 3,456 kgs.
//www.airbus.com/fileadmin/medi...h_data/AC/Airbus_AC_A330_Jan11.pdf
Twin spool engines have a more stable airflow pattern since the airflow is being compressed all the way to the last stage of the High Pressure Compressor (HPC) before it enters the diffuser section.
This makes the engine less surge prone in comparison to a three spool design. In a three spool engine, there is a sudden interruption (slowing down) of the airflow in the void between the Intermediate Compressor (IP) and the HP Compressor. When the compressed air leaves the last stage of blades of the IP compressor no more compression takes place until the first stage of the HP compressor blades. This airflow interruption between the two compressors in this uncompressed void makes the engine more surge prone.
The distance between the High Pressure Turbine (HPT) and the Intermediate Pressure Turbine (IPT) also hurts the triple spool's efficency. This distance is required to locate the disks around an extra pair of bearings.The hot gas flowing at a high subsonic speed in this void requires a lot of cooling air to be introduced which results in a considerable airflow loss that could be used for turning another turbine disk which would mean a lower fuel burn. But adding another turbine disk would increase the weight of the engine even more.
In a 3-spool engine, there is quite a bit of extra fuel burn due to the fan being oversped and the turbine powering it spinning below its optimal mach number.
Twin spool engines, (GE or Pratt) have less heat to dissipate than three spool (Rolls Royce) engines.
Three spool engines operate at a higher oil temperature when compared to twin spool engines and the oil distribution is much more complex in three spool engines.
This more complex oil distribution has given RR problems over the years, some call it oil hiding.
They have had to combat oil system problems with the RB211 / L1011; Trent 500 / A340-500/600’s; Trent 700 / A330 and Trent 900 / A380.
Oil Temperature comparisons.
RB211 Series 335'
Trent 700 374'
Trent 800 375'
Trent 900 385'
Trent 1000 365'
CF6-50 320'
CF6-80C2 320'
PW4000 350'
GE90 270'
Internal engine cooling airflow is less complex in a twin spool engine than in a three spool engine.
For this reason triple spool engines emit more smoke during start-up.
Twin spools engines (non contrarotating) have lower gyroscopic moments than triple spool engines, resulting in less side loading of the pod/strut.
Twin spools light off and accelerate faster than three spools.
Compare the slow spool-up time of a RR Trent compared to a GE or Pratt engine in the following link.
Most fighter aicraft engines use a twin spool design for faster throttle response.
Twin spool turbofans have the basic two spool configuration where both the fan and LP turbine (i.e. LP spool) are mounted on a second (LP) shaft, running concentrically with the HP spool (i.e. HP compressor driven by HP turbine). Twin spool engines have lower maunfacturing costs due to a lower parts count than three spool engines. Twin spools are less expensive to overhaul due to the fact that they have only two concentric drive shafts and support bearings.
Rolls-Royce chose a three spool configuration for their large civil turbofans, where the Intermediate Pressure (IP) compressor is mounted on a separate (IP) drive shaft, running concentrically with the LP and HP drive shafts, and is driven by a separate IP Turbine. However, three spool engines are more labor intensive to both build and maintain.
The Rolls Royce single stage High Pressure Turbine (HPT) is at a disadvantage to the competition due to the turbine blades being 30% heavier since they are shrouded at their tips. These heavier blades result in a longer time to reach optimum rotational speed for the HPT with it's coupled HP compressor. Shrouded blades decrease airflow leakage past the turbine blade tips but the unshrouded blades in GE and Pratt & Whitney engines are lighter which promotes faster engine acceleration. In twin spool engines manufactured by GE and Pratt, turbine blade tip airflow loss is reduced and controlled with a design known as Active Clearance Control (ACC) which also improves fuel efficency and lowers emissions. This clearance control design uses an ACC valve which captures cool ambient by pass airflow and routes this air to pipes with exit holes directed at the exterior surface of the turbine casing surrounding the turbine. This airflow reduces the thermal expansion of the turbine case and maintains the critical clearance between the turbine case and the blade tips. In other words, it shrinks the diameter of the turbine case and also allows it to expand when required.
Since three spool engines use three concentric shafts and more support bearings are than are required in twin spool engines. A three spool engine requires three compressors, a low pressure compressor, an intermediate compressor and a high pressure compressor, a high pressure turbine, an intermediate pressure turbine and a low pressure turbine. Twin spool engines have just two compressors, a low pressure and a high pressure compressor, a low pressure turbine and a high pressure turbine.
The RR three spool is more difficult and more labor intensive to manufacture because of the nature of the concentricity of the three drive shafts, support struts/bearings and the fact that is has three distinct compression and turbine stages.
Three spool engines are more labor intensive to balance and are more prone to vibration than twin spool engines.
An Oxford University/Rolls Study from 4/9/02 - 9/30/03 document notes that 10% or more of RR engines failed the final passing out test due to imbalance.
Eleven Trent 500 production engines failed pass-off testing due to abnormal vibrations. This indicates that there was a systemic vibration problem.
A higher rejection rate due to vibration is also detected when the engines are overhauled at the RR appointed agents than twin spool engines during overhaul.
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u.t.:
Item 3 is likely a no-brainer. If an aircraft receives original cert at xx MTOW with a heavy engine, and later a lighter engine is installed and cert, it will probably be at the same MTOW - i.e. greater useful load.
Then, assuming it's not ZFW-limited, the later version carries more payload, more $$$ income, more than making up for higher fees.
There are four prime factors to consider when comparing engines.
1. Purchase price.
2. Fuel burn.
3. Weight: lower weight means lower Air Traffic Control (ATC) fees if maximum Take-Off Weight (MTOW) is reduced or more revenue from a higher payload.
4. Maintenance cost.
1. Purchase price.
2. Fuel burn.
3. Weight: lower weight means lower Air Traffic Control (ATC) fees if maximum Take-Off Weight (MTOW) is reduced or more revenue from a higher payload.
4. Maintenance cost.
Then, assuming it's not ZFW-limited, the later version carries more payload, more $$$ income, more than making up for higher fees.
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A higher bypass pressure ratio (BPR) improves thermodynamic efficiency and also propulsive efficiency.
B777-200ER Engine comparisons:
GE GE90-94B
FAN DIAMETER: 123 Inches
COMPRESSOR LAYOUT: 1 Fan/3LP+10HP
TURBINE LAYOUT: 2HP+6LP
BPR: 8.40
MASS FLOW: 3398lb/s
TO THRUST: 93,700lbt
PRATT-WHITNEY PW4090
FAN DIAMETER: 112 Inches
COMPRESSOR LAYOUT: 1 Fan/6LP+11HP
TURBINE LAYOUT: 2HP+6LP
BPR: 6.41
MASS FLOW: 2948lb/s
TO THRUST: 90,100lbt
ROLLS-ROYCE TRENT 895
FAN DIAMETER: 110 Inches
COMPRESSOR LAYOUT: 1 Fan+8IP+7HP
TURBINE LAYOUT: 1HP+1IP+5LP
BPR: 5.74
MASS FLOW: 3123lb/s
TO THRUST: 93,100lbt
Engine Noise Comparisons:
GE90-94B
http://noisedb.stac.aviation-civile....df.php?id=8091
Lateral Full Power - 96.5 EPNdB.
Approach - 98
Flyover - 90.7
PW 4090
http://noisedb.stac.aviation-civile....df.php?id=8110
Lateral Full Power - 96.9 EPNdB.
Approach - 99.2
Flyover - 95.2
RR T895
http://noisedb.stac.aviation-civile....df.php?id=8129
Lateral Full Power - 98.3 EPNdB.
Approach - 99.4
Flyover 93.4
B777-200ER Engine comparisons:
GE GE90-94B
FAN DIAMETER: 123 Inches
COMPRESSOR LAYOUT: 1 Fan/3LP+10HP
TURBINE LAYOUT: 2HP+6LP
BPR: 8.40
MASS FLOW: 3398lb/s
TO THRUST: 93,700lbt
PRATT-WHITNEY PW4090
FAN DIAMETER: 112 Inches
COMPRESSOR LAYOUT: 1 Fan/6LP+11HP
TURBINE LAYOUT: 2HP+6LP
BPR: 6.41
MASS FLOW: 2948lb/s
TO THRUST: 90,100lbt
ROLLS-ROYCE TRENT 895
FAN DIAMETER: 110 Inches
COMPRESSOR LAYOUT: 1 Fan+8IP+7HP
TURBINE LAYOUT: 1HP+1IP+5LP
BPR: 5.74
MASS FLOW: 3123lb/s
TO THRUST: 93,100lbt
Engine Noise Comparisons:
GE90-94B
http://noisedb.stac.aviation-civile....df.php?id=8091
Lateral Full Power - 96.5 EPNdB.
Approach - 98
Flyover - 90.7
PW 4090
http://noisedb.stac.aviation-civile....df.php?id=8110
Lateral Full Power - 96.9 EPNdB.
Approach - 99.2
Flyover - 95.2
RR T895
http://noisedb.stac.aviation-civile....df.php?id=8129
Lateral Full Power - 98.3 EPNdB.
Approach - 99.4
Flyover 93.4
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unmanned transport
I hadn't looked at this thread for a while. You assembled a lot of good and interesting information in your most recent post as well as your #139 post.
One other advantage of a two spool engine is its more rapid air start time verses a three spool engine. There was an incident years ago involving a Delta Boeing 767-200 (GE CF6-80A engines) departing LAX for CVG where this advantage became very important.
30 June 1987; Delta Air Lines 767-200; Los Angeles, CA: The engines were inadvertently shut off during climb at about 2,000 feet. The crew was able to restart the engines at about 500 feet and continued to their original destination of Cincinnati.
I recall seeing data (think it was in Aviation Weekly) regarding the time to start GE, Pratt and RR engines after a flameout and both GE and Pratt engines had the shortest restart times by quite a bit verses the RR three spool engine (RB211).
TD
I hadn't looked at this thread for a while. You assembled a lot of good and interesting information in your most recent post as well as your #139 post.
One other advantage of a two spool engine is its more rapid air start time verses a three spool engine. There was an incident years ago involving a Delta Boeing 767-200 (GE CF6-80A engines) departing LAX for CVG where this advantage became very important.
30 June 1987; Delta Air Lines 767-200; Los Angeles, CA: The engines were inadvertently shut off during climb at about 2,000 feet. The crew was able to restart the engines at about 500 feet and continued to their original destination of Cincinnati.
I recall seeing data (think it was in Aviation Weekly) regarding the time to start GE, Pratt and RR engines after a flameout and both GE and Pratt engines had the shortest restart times by quite a bit verses the RR three spool engine (RB211).
TD
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Thanks again Turbine D.
It's my understanding that a triple spool engine requires a higher volume of air to start than a twin spool engine.
A twin spool engine produces more power from two High Pressure Turbines (HPT) driving it's coupled High Pressure Compressor (HPC) than one HPT as in a triple spool engine driving it's respective HPC. That's the main reason that RR will be adding an extra HPT disk in it's XWB series engines for improved efficency. This will add quite a bit more extra weight to this engine series and one could say that they are copying some of the twin spool advantages in turbine architecture.
A330-300 Estimated Maximum Payload.http://www.airbus.com/fileadmin/medi...A330_Jan11.pdf
Chapter 2-1-1 - page 1 - Revision Jan 01/11
CF6-80E1 - 52,169 kgs.- 115,012 lbs.
Trent 700 - 52,069 kgs. - 114,792 lbs.
A330-300 Airbus Payload / Range graphs.http://www.airbus.com/fileadmin/medi...A330_Jan11.pdf
Chapter 3-2-1 pages 6 & 7 Rev. Jan 01/11
CF6-80E1 - 6,625 nm.
Trent 700 - 6,500 nm.
It's my understanding that a triple spool engine requires a higher volume of air to start than a twin spool engine.
A twin spool engine produces more power from two High Pressure Turbines (HPT) driving it's coupled High Pressure Compressor (HPC) than one HPT as in a triple spool engine driving it's respective HPC. That's the main reason that RR will be adding an extra HPT disk in it's XWB series engines for improved efficency. This will add quite a bit more extra weight to this engine series and one could say that they are copying some of the twin spool advantages in turbine architecture.
A330-300 Estimated Maximum Payload.http://www.airbus.com/fileadmin/medi...A330_Jan11.pdf
Chapter 2-1-1 - page 1 - Revision Jan 01/11
CF6-80E1 - 52,169 kgs.- 115,012 lbs.
Trent 700 - 52,069 kgs. - 114,792 lbs.
A330-300 Airbus Payload / Range graphs.http://www.airbus.com/fileadmin/medi...A330_Jan11.pdf
Chapter 3-2-1 pages 6 & 7 Rev. Jan 01/11
CF6-80E1 - 6,625 nm.
Trent 700 - 6,500 nm.
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Sorry my mistake in the previous post.
Not an extra stage for the HPT but an extra stage for the IPT in the XWB engine.
HP turbine: single-stage, aircooled
IP turbine: two-stage, aircooled
LP turbine: 6-stage, uncooled
Not an extra stage for the HPT but an extra stage for the IPT in the XWB engine.
HP turbine: single-stage, aircooled
IP turbine: two-stage, aircooled
LP turbine: 6-stage, uncooled
The time it takes to restart is governed by the core inertia (HPT/HPC) being able to presurize the combustor to hold a flame. After that it is accel time limited.
I don't see the relationship in this thread of bringing in the Delta B767 since the core (HPT) hadn't spun down very much.
It's kind of subjective to argue good-better-best for products that all meet the same regulation and customer satisfaction levels as-installed.
I don't see the relationship in this thread of bringing in the Delta B767 since the core (HPT) hadn't spun down very much.
It's kind of subjective to argue good-better-best for products that all meet the same regulation and customer satisfaction levels as-installed.
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From all the data provided, we are just proving that twin spool engines have the 'edge' over the triple spool design. Less fuel burn and lower weight being the two big advantages for the twin spool. There are many misinformed people out there that think the triple spool is superior. This is not true but the reverse is true.
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Originally Posted by unmanned transport
From all the data provided, we are just proving that twin spool engines have the 'edge' over the triple spool design. Less fuel burn and lower weight being the two big advantages for the twin spool. There are many misinformed people out there that think the triple spool is superior. This is not true but the reverse is true.
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LOL sooty655
RR must have given those T900s free to Asiana for their A380s.
On another note,
PW seem to be on a roll with 1,200 orders so far for their GTF mill. Just wait until they scale this design up for wide body airframe use. I can very well see them becoming #2 again.
RR must have given those T900s free to Asiana for their A380s.
On another note,
PW seem to be on a roll with 1,200 orders so far for their GTF mill. Just wait until they scale this design up for wide body airframe use. I can very well see them becoming #2 again.
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We should also remember that Boeing only offer US engines on there 737, 747-8 and later 777's as a direct move to reduce certification costs. The 787 is the first new Boeing to offer the RR engine as well as a US engine.
It's my understanding that a triple spool engine requires a higher volume of air to start than a twin spool engine.
Does that contradict your statement?
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From the data provided by Turbine_D at post #126 the Trent is lighter than the GE..?
Trent882
Engine weight (dry): 12,009 lbs.
Overall length: 172 inches
Fan diameter: 110 inches
Thrust at TO: 80,711 lbs.
Thrust during Cruise: 15,917 lbs.
SFC (cruise): 15.66 mg/N-s
GE90
Engine weight (dry): 18,200 lbs.
Overall length: 187 inches
Fan diameter: 123 inches
Thrust at TO: 85,716 lbs.
Thrust during Cruise: 15,432 lbs.
SFC (cruise): 8.30 mg/N-s
Trent882
Engine weight (dry): 12,009 lbs.
Overall length: 172 inches
Fan diameter: 110 inches
Thrust at TO: 80,711 lbs.
Thrust during Cruise: 15,917 lbs.
SFC (cruise): 15.66 mg/N-s
GE90
Engine weight (dry): 18,200 lbs.
Overall length: 187 inches
Fan diameter: 123 inches
Thrust at TO: 85,716 lbs.
Thrust during Cruise: 15,432 lbs.
SFC (cruise): 8.30 mg/N-s
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Assuming these weights are accurate, one could cruise a good while longer when fuel is consumed at half the rate -- readily making up the engine weight difference.
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This link does not include the Trent 882 but I would expect it to weigh the same as the other 800 series weight.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/b443906400b2f413862572a4006eb74e/$FILE/E00050EN.pdf
RB211-TRENT 892-17, RB211-TRENT 875-17
RB211-TRENT 884-17, RB211-TRENT 884B-17
RB211-TRENT-892B-17, RB211-TRENT 895-17
RB211-TRENT 877-17
This engine approval includes bare engine plus engine mounting feet, core engine cowlings, and engine accessories, coolers, filters, harness, and instrumentation transmitters as defined in the appropriate RR DIS.
Hydraulic pump, VSCF and IDG are aircraft supply.
Dry powerplant weight less intake, intake systems, cowl doors, and cowl door support structure.
An inlet cowl is quite heavy.
GE90-76B thru 90B link:
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/8cf409747c1d7b1b86257823007a1b25/$FILE/E00049EN.pdf
WEIGHT (DRY) Includes basic engine, basic engine accessories, and optional equipment as listed in the manufacturer's engine specifications.
17,400 lbs.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/b443906400b2f413862572a4006eb74e/$FILE/E00050EN.pdf
RB211-TRENT 892-17, RB211-TRENT 875-17
RB211-TRENT 884-17, RB211-TRENT 884B-17
RB211-TRENT-892B-17, RB211-TRENT 895-17
RB211-TRENT 877-17
This engine approval includes bare engine plus engine mounting feet, core engine cowlings, and engine accessories, coolers, filters, harness, and instrumentation transmitters as defined in the appropriate RR DIS.
Hydraulic pump, VSCF and IDG are aircraft supply.
Dry powerplant weight less intake, intake systems, cowl doors, and cowl door support structure.
An inlet cowl is quite heavy.
GE90-76B thru 90B link:
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/8cf409747c1d7b1b86257823007a1b25/$FILE/E00049EN.pdf
WEIGHT (DRY) Includes basic engine, basic engine accessories, and optional equipment as listed in the manufacturer's engine specifications.
17,400 lbs.
Usual disclaimers apply!
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An inlet cowl is quite heavy
Inlet Cowl: 315kgs GE 355kgs Trent
Fan cowls: 140kgs GE 115kgs Trent
T/Rev halves: 800kgs GE 650kgs Trent
Trent 895 95k lbs of thrust (BET will be lower*)
The Trent weighs in at 7136kgs as an EBU (that includes all the boeing fit
components, so thats the nose cowl, IDG and hyd. pump).
The GE90 weighs in at 8500kgs as an EBU.
The base engine ranges from 76k to 94k*
*Boeing equivalent thrust (BET) is a calculated number. It is equivalent to
the thrust at 165 knots at sea level. BET is defined so that engines with the same BET will have the same TO perf. at sea level.
As TURIN says. The Triple spool needs a lot less air to start than the '90. A dual engine start is easily achieved on the Trent (I always do dual starts).
An inop APU can be a real PITA down route as you also need three ASU's for the GE90
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I am an economist, and the way we would evaluate which engine is superior is which airplane sells for a higher price. The all-in price of the plane should incorporate all of the engine considerations mentioned (initial cost, fuel cost, maintenance cost, thrust, etc.). One would only pay for plane equipped with XX engine versus YY engine if on net, XX engine is more economical.
While I am certainly not an expert on this, but it is my understanding that RR-equipped 757s sell at a higher price than PW-ones. While this is not definitive as to whether 2-spools are better/worse than 3-spools, it does suggest there are aspects of initial cost, fuel cost, maintenance cost, thrust, etc. in which the Roller must be better than the Pratt (unless the airline CEO just likes the look of interlocked Rs on cowling better than an eagle)
Of course it is also possible that different airlines' demands (lots of short hops and high cycles vs. long haul) could make Airline A find engine XX to be most economical while Airline B finds engine YY to be most economical.
Since both 2-spool and 3-spool models have been successful, it seems the latter explanation is likely.
While I am certainly not an expert on this, but it is my understanding that RR-equipped 757s sell at a higher price than PW-ones. While this is not definitive as to whether 2-spools are better/worse than 3-spools, it does suggest there are aspects of initial cost, fuel cost, maintenance cost, thrust, etc. in which the Roller must be better than the Pratt (unless the airline CEO just likes the look of interlocked Rs on cowling better than an eagle)
Of course it is also possible that different airlines' demands (lots of short hops and high cycles vs. long haul) could make Airline A find engine XX to be most economical while Airline B finds engine YY to be most economical.
Since both 2-spool and 3-spool models have been successful, it seems the latter explanation is likely.