Rolls-Royce Engines: Trent

Note: This is a sub-section of Rolls-Royce.

Introduction

Rolls Royce Trent is a family of high bypass turbofan engines manufactured by Rolls-Royce. All are developments of the RB211 with thrust ratings of between 53,000 and 95,000 lbf (236 to 423 kN). Versions of the Trent are in service on the Airbus A330, A340, A380 and Boeing 777, and variants are in development for the forthcoming 787 and A350. The Trent has also been adapted for marine and industrial applications.

The Trent has achieved significant commercial success, being the launch engine for all three 787 variants, the A380 and A350. Its overall share of the markets in which it competes is around 40%. Sales of the Trent family of engines have made Rolls-Royce the second biggest supplier of large civil turbofans after General Electric.

When Rolls-Royce was privatised in April 1987, its share of the large civil turbofan market was only 8 per cent. Despite increasing sales success with the RB211, General Electric and Pratt & Whitney still dominated the market. At that time, the aircraft manufacturers were proposing new planes that were going to require higher levels of thrust than before. The Boeing 777 and Airbus A330 were to be twin-engined, and their airline customers were demanding that they be capable of operating in the extended twin-engine operations environment (ETOPS) at the time of their initial introduction into service.

Rolls-Royce would have to offer engines for every large civil airliner. In view of the enormous development costs required to bring a new engine to market, the only way to do this would be to have a family of engines based on a common core. The three-shaft design of the RB211 was an ideal basis for the new family as it provided flexibility, allowing the high-pressure (HP), intermediate-pressure (IP) and low-pressure (LP) systems to be individually scaled. Recently freed from the restrictions of state ownership, Rolls decided to launch a new family of engines which was formally announced at the 1988 Farnborough Air Show.

Rolls-Royce has obtained significant sums of 'launch investment' from the British government for the Trent programmes, including £200 million approved in 1997 for Trent 8104, 500 & 600 and £250 million for Trent 600 & 900 in 2001. No aid was sought for Trent 1000. Launch investment is repaid to the government by a royalty on each engine sold.

Trent 600

The initial variant, Trent 600, was to power the McDonnell Douglas MD-11 with British Caledonian as the engine's launch customer. However, when British Airways bought British Caledonian in 1987, they cancelled the MD-11 order. With the collapse in 1991 of Air Europe in the aftermath of the 1990 Gulf War, the only other Trent-powered MD-11 customer was lost. As the MD-11 was itself suffering poor sales due to its failure to meet its performance targets, the Trent 600 was downgraded to a demonstrator programme, engine development being switched to the Trent 700 for the Airbus A330.

Trent 700

When Airbus was planning its new twin-jet A330 in the late 1980s, Rolls-Royce at first proposed a version of the Trent 600 - the Trent 680 - to power it. However, as the A330's design weight increased, it became clear that more thrust would be required and Rolls proposed the Trent 720, the first member of the Trent 700 series.

In April 1989 Cathay Pacific became the first customer to specify an Airbus aircraft powered by Rolls-Royce engines when it ordered ten A330s powered by the Trent 700. The following month TWA followed suit with an order for twenty A330s.

The Trent 700 first ran in August 1990, and certification was achieved in January 1994. 90 minutes ETOPS approval was achieved in March 1995, and this was extended to 120 minutes in December 1995 and 180 minutes in May 1996.

Rolls-Royce claim that the Trent 700 is the quietest and cleanest engine available on the A330. Emirates and Cathay Pacific are the largest operators, each with 29 Trent 700-powered A330s. Sales of the engine are still strong: Rolls received orders for 140 of the type during the Paris Air Show in June 2007. The Trent 700 has captured a 41% share of the A330 engine market to date, with 42 customers and operators worldwide.

The Trent 700 family powers the Airbus A330. It comes in 2 thrust ratings, 67,500 and 71,000 lbf (300 to 316 kN). It first entered service on Cathay Pacific A330s in March, 1995.

Three-shaft high bypass ratio 5.0
Fan diameter: 97.4 inches (2.47 metres)
Eight-stage IP compressor
Six-stage HP compressor
Single annular combustor with 24 fuel injectors
Single-stage HP turbine
Single-stage IP turbine
Four-stage LP turbine

Trent 800

At the same time Boeing were investigating an enlarged development of its 767 model dubbed the 767X, for which Rolls-Royce proposed the Trent 760.

By 1990 Boeing abandoned its planned 767X and instead decided to launch a new, larger aircraft family designated 777 with a thrust requirement of 80,000 lbf or more. The Trent 700's 97.4 inch diameter fan would not be big enough to meet this requirement, so Rolls proposed a new version with a 110 inch fan diameter, designated Trent 800. Rolls brought in Kawasaki Heavy Industries and Ishikawajima-Harima Heavy Industries as risk and revenue sharing partners who between them took an 11 per cent stake in the Trent 700 and 800 programmes.

Testing of the Trent 800 began in September 1993, and certification was achieved in January 1995. The first Boeing 777 with Trent 800 engines flew in May 1995, and entered service with Cathay Pacific in April 1996. 180 minutes ETOPS approval was granted by the FAA on 10 October 1996.

Initially Rolls-Royce had difficulty selling the engine: British Airways, traditionally a Rolls-Royce customer, submitted a big order for the competing General Electric GE90 engine.

The breakthrough came when the company won orders from Singapore Airlines, previously a staunch Pratt & Whitney customer, for its 34 Boeing 777s; this was soon followed by large North American orders from American Airlines and Delta Air Lines for their 777 fleets. British Airways announced in September 1998 that it was returning to Rolls-Royce for its second batch of 777s, and did so again in April 2007. The Trent 800 has a 43% share of the engine market on the 777 variants for which it is available.

The Trent 800 family powers the Boeing 777. It is available on the 777-200, 777-200ER, and 777-300 variants, with thrust ratings spanning 75,000 to 95,000 lbf (334 to 423 kN). No airline operates the engine with greater than 93,400lbf thrust however, as it has yet to be certified to any higher level for commercial operations. The engine is one of the lightest in its class; a Trent-powered Boeing 777 weighs up to 3.6 metric tons less than General Electric and Pratt & Whitney-powered versions.

Three-shaft high bypass ratio 6.2 - 5.7
Fan diameter: 110 inches (2.79 metres)
Eight-stage IP compressor
Six-stage HP compressor
Single annular combustor with 24 fuel injectors
Single-stage HP turbine
Single-stage IP turbine
Five-stage LP turbine

Trent 8104

In 1998 Boeing proposed new longer range variants of the 777X; taking advantage of the Trent 800's growth capability, Rolls-Royce designed and built an improved engine designated Trent 8104 which was later scaled upwards to the even larger 8115. However, Boeing required that the participating engine developer assume a risk-sharing role on the overall 777X project. Rolls-Royce was unwilling to do so, and in July 1999 Boeing announced that it had chosen advanced developments of the GE90, the GE90-110B and GE90-115B to be the sole engines on the long-range 777s. This relegated the 8104 to the role of demonstrator engine.

Originally designed for the 777-200LR and 777-300ER (both part of the 777X project), this engine comes in two thrust ratings, 104,000 and 114,000 lbf (463 to 507 kN), and has been tested up to 117,000 lbf (520 kN). As Boeing's thrust requirements increased, Rolls-Royce began developing the 115,000 lbf 8115 which was to be an enlarged version of the 8104, with a 120 inch (3.048 metre) fan and a core scaled up 2.5 per cent from the 8104. It featured swept-back fan blades and a host of new technologies such as contra-rotating spools.

The 8115 was never built, as Boeing signed a contract with General Electric to be the sole supplier of engines for the 777X aircraft, owing to GEs willingness to risk-share on the airframe part of the project, and sales of the aircraft to GECAS.

Trent 500

In 1995 Airbus began considering an engine for two new long-range derivatives of its four-engined A340 aircraft, designated A340-500/-600. The existing -200 and -300 models were powered by CFM International CFM56 engines (which had been selected in April 1987 before the Trent family was launched). However, the CFM56 was at the limit of its development capability, and would be unable to power the new A340-500/-600.

In April 1996 Airbus signed an agreement with General Electric to develop a suitable engine, but decided not to proceed when GE demanded an exclusivity deal on the A340. After a contest with Pratt & Whitney, Airbus announced on 15 June 1997 at the Paris Air Show that it had selected the Trent 500 to power the A340-500 and -600.

The Trent 500 first ran in May 1999 and achieved certification in December 2000. It entered service on the A340-600 with Virgin Atlantic Airways in July 2002 and on the ultra-long range A340-500 with Emirates in December 2003.[11] As at July 2007 Lufthansa is the largest operator of A340s powered by Trent 500s with 17 delivered to date. A total of 15 customers have placed firm orders for over 150 aircraft.

The Trent 500 powers the Airbus A340-500 and A340-600. It was certificated at 60,000 lbf (267kN) thrust, but derated to 53,000 lbf (236kN) as the Trent 553 to power the A340-500, and to 56,000 lbf (249 kN) as the Trent 556 for the A340-600 and A340-500HGW. However, a 60,000 lbf (267kN) version is installed in the A340-600HGW (High Gross Weight), a higher-performance version of the A340-600. The Trent 500 has the same wide-chord fan as the Trent 700, together with a core scaled from the Trent 800.

Three-shaft high bypass ratio 7.6 - 7.5
Fan diameter: 97.4 inches (2.47 metres)
Eight-stage IP compressor
Six-stage HP compressor
Tiled combustor with 20 fuel injectors
Single-stage HP turbine
Single-stage IP turbine
Five-stage LP turbine

Trent 900

In the early 1990s Airbus had begun development of a larger successor to the Boeing 747, an aircraft designated A3XX, which was later to be formally launched as the A380.

By 1996 its definition had progressed to the extent that Rolls-Royce was able to announce that it would develop the Trent 900 to power the A380.

In October 2000, the Trent 900 became the A380's launch engine when Singapore Airlines specified the engine for its order for 10 A380s; this was quickly followed by Qantas in February 2001.

Rolls-Royce has seven risk and revenue sharing partners on the Trent 900: Industria de Turbo Propulsores (low pressure turbine), Hamilton Sundstrand (electronic engine controls), Avio S.p.A. (gearbox module), Marubeni Corporation (engine components), Volvo Aero (intermediate compressor case), Goodrich Corporation (fan casings and sensors) and Honeywell (pneumatic systems). In addition, Samsung Techwin, Kawasaki Heavy Industries and Ishikawajima-Harima Heavy Industries (IHI) are programme associates.

The Trent 900 made its maiden flight on May 17, 2004 on Airbus' A340-300 testbed, replacing the port inner CFM56-5 engine, and its final certification was achieved by EASA on 29 October 2004 and FAA on 4 December 2006.[13][14] Rolls-Royce announced in October 2007 that production of the Trent 900 had been re-started after a twelve month suspension caused by delays to the A380.[15]

On 27 September 2007 British Airways announced the selection of the Trent 900 to power 12 A380 aircraft, helping to take the engine's share of the A380 engine market to 53% at the end of December 2007.

The Trent 900 family powers the Airbus A380. It comes in two thrust ratings, 70,000 and 76,000 lbf (311 and 338 kN) but is capable of achieving 84,000 lbf (374 kN). It features a significant amount of technology inherited from the 8104 demonstrator including its 2.95 m diameter swept-back fan which provides greater thrust for the same engine size, and is also about 15 per cent lighter than previous wide-chord blades. It is also the first member of the Trent family to feature a contra-rotating HP spool and uses the core of the very reliable Trent 500. It is the only A380 engine that can be transported on a Boeing 747 freighter.

Whereas most members of the Trent family are controlled by Goodrich FADECs, engine controllers on the Trent 900 are provided by Hamilton Sundstrand, a United Technologies (UTC) company. UTC is also the parent company of Pratt & Whitney, who, with GE Aircraft Engines, is partnering to produce the Engine Alliance GP7000, the other engine available for the A380. This kind of cooperation among competitors is prevalent in the aircraft market as it provides for risk sharing among them and diversity in source countries, a significant factor in an airlines' choice of airframe and powerplant.

The Trent 900 will be the first Trent engine fitted with the advanced Engine Health Monitoring (EHM) system based on QUICK TechnologyTM.

General characteristics

Type: Three-shaft high bypass ratio (8.7 - 8.5) turbofan engine
Length: 179 in
Diameter: , fan tip 116 in
Dry weight: 13,825 lb

Components

Compressor: Eight-stage IP compressor, six-stage HP compressor
Combustors: Tiled combustor
Turbine: Single-stage HP turbine, single-stage IP turbine, five-stage LP turbine

Performance

Power output:
Overall pressure ratio: 37-39
Thrust-to-weight ratio: 4.93 - 5.63 (assuming 14,190 lbf weight of engine and certified to 70,000 - 80,000 lbf of thrust)

Trent 600 (second proposal)

In July 2000 Rolls-Royce signed an agreement with Boeing to offer the Trent 600 engine on developments of 767 and 747 aircraft. The 767 variant was to be a new longer-range version of the Boeing 767-400ER to be powered by the Trent 600 and Engine Alliance GP7172, although in the end this aircraft was never launched. When Boeing finally launched the 747-8 in 2005 it announced that the General Electric GEnx would be the only engine available for the 747-8.

Trent 1000

On April 6, 2004 Boeing announced that it had selected two engine partners for its new 787: Rolls-Royce and General Electric. Initially, Boeing toyed with the idea of sole sourcing the powerplant for the 787, with GE being the most likely candidate. However, potential customers demanded choices and Boeing relented. For the first time in commercial aviation, both engine types will have a standard interface with the aircraft, allowing any 787 to be fitted with either a GE or Rolls-Royce engine at any time.

As with earlier variants of the Trent family, Rolls partnered with risk and revenue sharing partners on the Trent 1000 programme. This time there were six partners: Kawasaki Heavy Industries (intermediate compressor module), Mitsubishi Heavy Industries (combustor and low pressure turbine blades), Industria de Turbo Propulsores (low pressure turbine), Carlton Forge Works (fan case), Hamilton Sundstrand (gearbox) and Goodrich Corporation (engine control system). Between them these partners have a 35 per cent stake in the programme.

In June 2004, the first public engine selection was made by Air New Zealand who chose the Trent 1000 for its two firm orders. In the largest 787 order, that of Japan's All Nippon Airways, Rolls-Royce was selected as the engine supplier on October 13, 2004. The deal is valued at $1bn (£560m) and covers 30 787-3s and 20 787-8s. The Trent 1000 is to be the launch engine on all three current 787 models, the -3 and -8 with ANA and the -9 with Air New Zealand.[19] On July 7, 2007, Rolls Royce secured its largest ever order from an aircraft leasing company when ILFC placed an order worth $1.3 billion at list prices for Trent 1000s to power 40 of the 787s which it has on order,[20] and on September 27, 2007 British Airways announced the selection of the Trent 1000 to power 24 Boeing 787 aircraft. Trent 1000's share of the 787 engine market was 39% at the end of November 2007.

The first run of the Trent 1000 was on 14 February 2006, with first flight on Rolls-Royce's own flying testbed (a modified Boeing 747-200) successfully performed on June 18, 2007 from TSTC Airport in Waco, TX. The engine received joint certification from the FAA and EASA on August 7, 2007. Entry into service is currently scheduled for December 2008 following Boeing's announcement in October 2007 that 787 deliveries would be delayed by six months.[24]

The Trent 1000 family powers the Boeing 787. The technology found in the Trent 8104 demonstrator is used extensively. The Trent 1000 is a bleedless design, with power take-off from the intermediate-pressure spool instead of the high-pressure spool found in other members of the Trent family, to fulfill the Boeing requirements of a "more-electric" engine. A 112-inch diameter swept-back fan, with a smaller diameter hub to help maximize airflow, was specified. Bypass ratio has been increased over previous variants by suitable adjustments to the core flow. Contra-rotating the IP and HP spools improves IP turbine efficiency, while use of more monolithic parts reduces the parts count for lower maintenance costs. A tiled combustor is featured.

Three-shaft high bypass ratio 11 - 10.8
Overall pressure ratio (Top-of-Climb) 52:1
Fan diameter: 112 inches (2.85 metres)
Take-off thrust: 53000 - 75000 lbf (flat-rated to ISA+15C)
Airflow: 2400 - 2670 lb/s
Single-stage LP compressor
Eight-stage IP compressor
Six-stage HP compressor
Tiled combustor
Single-stage HP turbine
Single-stage IP turbine
Six-stage LP turbine

Trent 1500

A Trent 500 replacement engine, known unofficially as the Trent 1500, has been proposed for the Airbus A340-500/600, to help the aircraft compete with the Boeing 777-200LR/300ER. However, the announcement of the A350 XWB, which covers the A340 market, will most likely prevent the Trent 1500 from ever becoming a reality.

The Trent 1500 would retain the 97.4in fan diameter of the current Trent 500 engine, as well as the nacelle, but incorporate the smaller, more advanced, Trent 1000/XWB gas generator and LP turbine, suitably modified.

Trent XWB

By 2004 Airbus was facing pressure from customers to develop a competitor for Boeing's 787, and in October 2005 formally launched the new aircraft designated A350, which was to be essentially an updated A330. Rolls-Royce offered a variant of the Trent 1000, dubbed Trent 1700 which would have been similar to the Trent 1000, but with a throttle-push to 75000lbf static thrust. Unlike the Trent 1000, the Trent 1700 would have been a conventional bleed-air engine,[26] and would be developed in partnership with Kawasaki. After a lukewarm response from the airlines, Airbus reviewed their A350 proposal, and on 17 July 2006 announced that they would be offering instead an all-new aircraft called the A350 XWB (Xtra Wide-Body), with a fuselage diameter slightly greater than that of Boeing's 787, to compete with both the 787 and the 777.

Rolls-Royce has reached an agreement with Airbus to supply a new variant, currently called the Trent XWB, for all versions of the Airbus A350 XWB. Originally announced with a static thrust range of 75,000-95,000lbf, by September 2007 Airbus had revised their requirments down to 74,000-92,000 lbf. Certification is planned for 2011, with the 83,000lbf Trent XWB-83's entry into service on the A350 XWB-900 expected in 2013.

This will be followed by the 74,000lbf Trent XWB-74 in 2014 on the A350 XWB-800, and finally the 92,000lbf Trent XWB-92 on the A350 XWB-1000 in 2015. General Electric has yet to confirm that it will offer a GEnx variant for the A350 XWB. Flight International magazine has suggested that the GE/Pratt and Whitney Engine Alliance GP7000 may be the second engine option for the aircraft, at least on the smaller variants.

On 18 June 2007, Rolls-Royce announced that it had signed its biggest ever contract with Qatar Airways for the Trent XWB to power 80 A350 XWBs on order from Airbus worth $5.6 billion at list prices.

On 11 November 2007, another large contract was announced at the Dubai Airshow from Emirates Airline for Trent XWBs to power 50 A350-900 and 20 A350-1000 aircraft with 50 option rights. Due to be delivered from 2014, the order is potentially worth up to 8.4 billion US Dollars at list prices, including options.[33] At the end of October 2007 Rolls-Royce had secured orders for engines to power a total of 302 A350 aircraft.

The Trent XWB family is planned to power the Airbus A350. Originally intended to have the same 112in diameter fan of the Trent1000/Trent1700, Rolls-Royce have now announced an increase in diameter to 118in for the Trent XWB, to keep the take-off jet noise acceptable at the increased thrust level. The company will probably also have to increase the core flow, to moderate the HP turbine rotor inlet temperature. They are unlikely to increase overall pressure ratio significantly to gain core flow, because this parameter is already very high, so some increase in core size is almost inevitable.

Three-shaft high bypass ratio:
Fan diameter: 118 inches (3.0 metres)
Fan: single stage, swept, low hub:tip ratio
IP compressor:8 stage axial
HP compressor:6 stage axial
HP turbine:single-stage, aircooled
IP turbine:single-stage
LP turbine:6-stage, uncooled

Design

Like its predecessor RB211, the Trent uses a three-spool design rather than the more common two-spool configuration. Although inherently more complex, it results in a lighter, shorter, more rigid engine which suffers less performance degradation in service than an equivalent twin-spool.

Although all the engines in the Trent family share a similar layout, their three-spool configuration allows each engine module to be individually scaled to meet a wide range of performance and thrust requirements. For example, the large 116 inch diameter fan of the Trent 900 keeps the mean jet velocity at take-off at a relatively low level to help meet the stringent noise levels required by the Airbus A380's customers. Similarly, core size changes enable the (HP) turbine rotor inlet temperature to be kept as low as possible, thereby minimising maintenance costs. The overall pressure ratio of the Trent 800 is higher than the 700's despite sharing the same HP system and IP turbine; this was achieved by increasing the capacity of the IP compressor and the LP turbine.

The core turbomachinery is brand new, giving better performance, noise and pollution levels than the RB211. So significant were the improvements that Rolls-Royce fitted the Trent 700's improved HP system to the RB211-524G and -524H,[35] creating -524G-T and -524H-T respectively.

When the RB211 programme originally started, it was intended that none of the compression system would require variable stators, unlike the American competition. Unfortunately, it was found that, because of the shallow working line on the IPC, at least one row of variable stators was required on the IPC, to improve its surge margin at throttled conditions. This feature has been retained throughout the RB211 and Trent series. Although the original intent was not met, Rolls-Royce eliminated the need for many rows of variable stators, with all its inherent complexity, thereby saving weight, cost and improving reliability.

Sources of Information

[1] Wikipedia

Grace's Guide To British Industrial History