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.