Rolls-Royce RB211

RB211
Rolls Royce RB211-524C2 engine on a Bahrain Air Force Boeing 747SP
Type Turbofan
National origin United Kingdom
Manufacturer Rolls-Royce
First run 1969
Major applications Boeing 747
Boeing 757
Boeing 767
Lockheed L-1011 TriStar
Tupolev Tu-204
Developed into Rolls-Royce Trent

The Rolls-Royce RB211 is a British family of high-bypass turbofan engines made by Rolls-Royce plc. Mismanagement of the development and consequent cost issues led to the effective nationalisation of Rolls-Royce Limited in order to save the workforce and the engine businesses important to the nation, and many other aerospace and aircraft operating companies.

The engines are capable of generating 37,400 to 60,600 pounds-force (166 to 270 kilonewtons) thrust.

Originally developed for the Lockheed L-1011 TriStar, it entered service in 1972 and was the only engine to power this type of aircraft. Its RB211 engine was the first production three-spool engine, and it was to turn Rolls-Royce from a significant player in the aero-engine industry into a global leader. Already in the early 1970s the engine was reckoned by the company to be capable of at least 50 years of continuous development.[1][2]

The RB211 was officially superseded in the 1990s by the Rolls-Royce Trent family of engines, the conceptual offspring of the RB211.[1]

History

Background

In 1966 American Airlines announced a requirement for a new short-medium range airliner with a focus on low-cost per-seat operations. While it was looking for a twin-engined plane, the aircraft manufacturers needed more than one customer to justify developing a new airliner. Eastern Airlines was also interested, but required greater range and needed to operate long routes over water; at the time, this demanded three engines in order to provide redundancy. Other airlines also favored three engines. Lockheed and Douglas responded with designs, the L-1011 TriStar and DC-10 respectively. Both had three engines, transcontinental range and seated around 300 passengers in a widebody layout with two aisles.

Both planes also required new engines. Engines were undergoing a period of rapid advance due to the introduction of the high bypass concept, which provided for greater thrust, improved fuel economy and less noise than the earlier low-bypass designs. Rolls-Royce had been working on an engine of the required 45,000 lbf (200 kN) thrust class for an abortive attempt to introduce an updated Hawker Siddeley Trident as the RB178. This work was later developed for the 47,500 lbf (211 kN) thrust RB207 to be used on the Airbus A300, before it was cancelled in favour of the RB211 programme.

Meanwhile, Rolls-Royce was also working on a series of triple-spool[3] designs as replacements for the Conway, which promised to deliver higher efficiencies. In this configuration, three groups of turbines spin three separate concentric shafts to power three sections of the compressor area running at different speeds. In addition to allowing each stage of the compressor to run at its optimal speed, the triple-spool design is also more compact and rigid, although more complex to build and maintain. Several designs were being worked on at the time, including a 10,000 lbf (44 kN) thrust design known as the RB203 intended to replace the Rolls-Royce Spey. Work started on the Conway replacement engine in July 1961 and a twin-spool demonstrator engine to prove the HP compressor, combustor, and turbine system designs, had been run by 1966. Rolls-Royce chose the triple-spool system in 1965 as the simplest, lowest cost solution to the problem of obtaining lower fuel consumption and reduced noise levels at a constant power setting. Work on the RB211 as essentially a scaled-down RB207 began in 1966-7 with the first certificated engines being scheduled to be available by December 1970 at 33,260lb take-off thrust and at a price of $511,000 each.[4]

Finalisation of design

On 23 June 1967, Rolls-Royce offered Lockheed the RB211-06 for the L-1011. The new engine was to be rated at 33,260 lbf (147,900 N) thrust and combined features of several engines then under development: the large high-power, high-bypass design from the RB207 and the triple-spool design of the RB203.[5] To this was added one new piece of technology, a fan stage built of a new carbon fibre material called Hyfil developed at the RAE Farnborough. The weight saving was considerable over a similar fan made of titanium, and gave the RB211 an advantage over its competitors in terms of power-to-weight ratio. Despite knowing that the timetable was challenging for an engine incorporating these new features, Rolls-Royce committed to putting the RB211 into service in 1971.[6]

Lockheed felt that the new engine enabled the L-1011 to offer a distinct advantage over the otherwise similar DC-10 product. However, Douglas had requested proposals from Rolls-Royce for an engine to power its DC-10, and in October 1967 the response was a 35,400 lbf (157,000 N) thrust version of the RB211 designated RB211-10. There followed a period of intense negotiation between airframe manufacturers Lockheed and Douglas, engine suppliers Rolls-Royce, General Electric and Pratt & Whitney, and the major U.S. airlines. During this time prices were negotiated downwards and the required thrust ratings were raised ever higher. By early 1968, Rolls-Royce was offering a 40,600 lbf (181,000 N) thrust engine designated RB211-18. Finally, on 29 March 1968 Lockheed announced that it had received orders for 94 TriStars, and placed an order with Rolls-Royce for 150 sets of engines designated RB211-22.[6][7]

RB211-22 series

Development and testing

The RB211's complexity required a lengthy development and testing period. By Autumn 1969 Rolls-Royce was struggling to meet the performance guarantees to which it had committed: the engine had insufficient thrust, was over-weight and its fuel consumption was too high. The situation deteriorated further when in May 1970 the new Hyfil (a carbon fibre composite) fan stage, after passing every other test, shattered into pieces when a chicken was fired into it at high speed.[8] Rolls had been developing a titanium blade as an insurance against difficulties with Hyfil, but this meant extra cost and more weight.[9] It also brought its own technical problems when it was discovered that only one side of the titanium billet was of the right metallurgical quality for blade fabrication.

In addition, the project had suffered a serious setback with the sudden death of Chief Engineer Adrian "Lom" Lombard in July 1967, a loss that was described as Rolls-Royce having been "deprived of one of the finest trouble-shooting engineers in the industry".[10]

"It was all too obvious that the Derby engineers, normally proud and self-confident to the point of arrogance, had slid from bad to worse when their great leader, Lombard, had been so suddenly plucked from them in 1967. His death had left a vacuum which nobody could fill ... " - Stanley Hooker [11][12]

In September 1970, Rolls-Royce reported to the government that development costs for the RB211 had risen to £170.3 million - nearly double the original estimate; furthermore the estimated production costs now exceeded the £230,375 selling price of each engine.[6] The project was in crisis.[13]

Insolvency and aftermath

By January 1971 Rolls-Royce had become insolvent, and on 4 February 1971 was placed into receivership,[note 1] seriously jeopardising the L-1011 TriStar programme. Because of its strategic importance, the company was nationalised by the then-Conservative government of Edward Heath, allowing development of the RB211 to be completed.[14]

As Lockheed was itself in a vulnerable position, the British government required that the US government guarantee the bank loans that Lockheed needed to complete the L-1011 project. If Lockheed (which was itself weakened by the difficulties) had failed, the market for the RB211 would have evaporated. Despite some opposition, the US government provided these guarantees.[15] In May 1971, a new company called "Rolls-Royce (1971) Ltd." acquired the assets of Rolls-Royce from the Receiver, and shortly afterwards signed a new contract with Lockheed. This revised agreement cancelled penalties for late delivery, and increased the price of each engine by £110,000.[16]

Hugh Conway (managing director RR Gas Turbines), persuaded Stanley Hooker to come out of retirement and return to Rolls Royce.[17][18] As technical director he led a team of other retirees - including Cyril Lovesey and Arthur Rubbra - to fix the remaining problems on the RB211-22. The engine was finally certified on 14 April 1972,[19] about a year later than originally planned, and the first TriStar entered service with Eastern Air Lines on 26 April 1972. Hooker was knighted for his role in 1974.[20]

Speaking of a famous banker in relation to the RB211:

"We (Rolls-Royce) added a zero to his stature; he used to think £5 million a lot of money, but after a few weeks on the RB211 he came to understand that £50 million is peanuts." - Stanley Hooker.[21]

The RB211's initial reliability in service was not as good as had been expected because of the focus of the development programme on meeting the engine's performance guarantees. Early deliveries were of the RB211-22C model, derated slightly from the later -22B. However, a programme of modifications during the first few years in service improved matters considerably, and the series has since matured into a highly reliable engine.

RB211-524 series

RB211-524 on a Qantas Boeing 747-300

Although originally designed for the L-1011-1, Rolls-Royce knew that the RB211 could be developed to provide greater thrust. By redesigning the fan and the IP compressor, Hooker's team managed to increase the engine's thrust to 50,000 lbf (220 kN). The new version, which first ran on 1 October 1973,[22] was designated RB211-524, and would be able to power new variants of the L-1011, as well as the Boeing 747.

Rolls-Royce had tried without success to sell the RB211 to Boeing in the 1960s, but the new -524 offered significant performance and efficiency improvements over the Pratt & Whitney JT9D which Boeing had originally selected to power the 747. In October 1973 Boeing agreed to offer the RB211-524 on the 747-200, and British Airways became the first airline to order this combination which entered service in 1977. Flight International stated in 1980:

"The importance placed on fuel saving by airlines is emphasised by Qantas' adoption of RB.211-524 power for its new Boeing 747s - the only aircraft on which all big three fans are available. Qantas found that British Airways' Boeing 747s fitted with RB.211s burnt roughly 7 per cent less fuel than its JT9D-equipped fleet, a saving of about $1 million a year at today's prices." [23]

Rolls continued to develop the -524, increasing its thrust through 51,500 lbf (229 kN) with the -524C, then 53,000 lbf (240 kN) in the -524D which was certificated in 1981. Notable airline customers included Qantas, Cathay Pacific, Cargolux and South African Airways. When Boeing launched the larger 747-400 still more thrust was required, and Rolls responded with the -524G rated at 58,000 lbf (260 kN) thrust and then the -524H with 60,600; these were the first versions to feature FADEC.[24] The -524H was also offered as a third engine choice on the Boeing 767, and the first of these entered service with British Airways in February 1990.

These would have been the final developments of the -524, but when Rolls developed the successor Trent engine, it found it could fit the Trent 700's improved HP system to the -524G and -524H. These variants were lighter and offered improved fuel efficiency and reduced emissions;[25] they were designated -524G-T and -524H-T respectively. It was also possible to upgrade existing -524G/H engines to the improved -T configuration, and a number of airlines did this.[26]

The -524 became increasingly reliable as it was developed,[27] and the -524H achieved 180-minute ETOPS approval on the 767 in 1993. An RB211 may have a thrust specific fuel consumption around 0.6 lb/(lbf·h).[28]

The -524L, begun in 1987 to allow further growth in the A330 and 777 market, was more extensively redesigned, the considerable differences incorporated leading to the engine eventually receiving the name 'Trent', under which name development has continued.[22]

RB211-535 series

Rolls-Royce RB211-535E4B on Icelandair Boeing 757-300 "Hengill"
An American Airlines Boeing 757-200 powered by RB211 engines.

In the mid 1970s, Boeing was considering designs for a new twin-engined aircraft to replace its highly successful 727. As the size of the proposed plane grew from 150 passengers towards 200, Rolls-Royce realised that the RB211 could be adapted by reducing the diameter of the fan and removing the first IP compressor stage to produce an engine with the necessary 37,400 lbf (166,000 N) thrust. The new version was designated RB211-535. On 31 August 1978 Eastern Airlines and British Airways announced orders for the new 757, powered by the -535. Designated RB211-535C, the engine entered service in January 1983; this was the first time that Rolls-Royce had provided a launch engine on a Boeing aircraft. Eastern Airlines president Frank Borman called the -535C "The finest airline engine in the world".[29]

However, in 1979 Pratt & Whitney launched its PW2000 engine, claiming 8% better fuel efficiency than the -535C for the PW2037 version. Boeing put Rolls-Royce under pressure to supply a more competitive engine for the 757, and using the more advanced -524 core as a basis, the company produced the 40,100 lbf (178,000 N) thrust RB211-535E4 which entered service in October 1984. While still not quite as efficient as the PW2037, it was more reliable and quieter. Visible differences include a mixed exhaust nozzle and a bigger fan cone. It was also the first to use the wide chord fan which increases efficiency, reduces noise and gives added protection against foreign object damage. As a result, a relatively small number of -535C's were installed on production aircraft, almost all -535Cs are still used with Boeing 757-200s owned by DHL and one aircraft is a charter jet. The majority uses the -535E.

Probably the most important single -535E order came in May 1988 when American Airlines ordered 50 757s powered by the -535E4 citing the engine's low noise as an important factor: this was the first time since the TriStar that Rolls-Royce had received a significant order from a US airline, and it led to the -535E4's subsequent market domination on the 757. Humorously (as reported in Air International) at the time of the announcement made by American, selection of the -535E4 was made public prior to the selection of the 757, though this was welcome news to both Rolls-Royce and Boeing.

After being certified for the 757, the E4 was offered on the Russian Tupolev Tu-204-120 airliner, entering service in 1992. This was the first time a Russian airliner had been supplied with western engines.[30] The -535E4 was also proposed by Boeing for re-engining the B-52H Stratofortress, replacing the aircraft's eight TF33s with four of the turbofans. Further upgrading of the -535E4 took place in the late 1990s to improve the engine's emissions performance, borrowing technology developed for the Trent 700.[31]

The -535E4 is an extremely reliable engine,[32] and achieved 180-minute ETOPS approval on the 757 in 1990.

Industrial RB211

When Rolls-Royce was developing the -22, it realised that it would be straightforward to develop a version of the engine for land-based power generation, and in 1974 the industrial RB211 was launched. When the -524 arrived shortly afterwards, its improvements were incorporated in the industrial RB211 which was designated RB211-24. The generator was gradually developed over the following years[33] and is still marketed today as a range of generators producing 25.2–32 MW.[34] Many of its installations have been in the offshore oil and gas production industries.

Marine WR-21

An advanced 25 MW class WR-21 Intercooled Recuperated (ICR) gas turbine was derived for marine propulsion.

Specifications

The family is divided into three distinct series:

RB211-22 series

RB211-524 series

A British Airways 747-400 powered by the RB211-524G

RB211-524 :[35]

RB211-535 series

The -535E4 was the first engine to incorporate a hollow wide-chord unsnubbered[note 2] fan to improve efficiency. It also used more advanced materials, including titanium in the HP compressor and carbon composites in the nacelle. Later engines incorporate some features (e.g. FADEC) from improved models of the -524.

Leading particulars

RB211 engine family: leading particulars[36]
Engine Static thrust Basic engine weight Length (in) Fan diameter Entry into service Applications
RB211-22B 42,000 lbf (190 kN) 9,195 lb (4,171 kg) 119.4 84.8 in (2.15 m) 1972 Lockheed L-1011-1, Lockheed L-1011-100
RB211-524B2 50,000 lbf (220 kN) 9,814 lb (4,452 kg) 119.4 84.8 in (2.15 m) 1977 Boeing 747-100B, Boeing 747-200, Boeing 747SP
RB211-524B4 53,000 lbf (240 kN) 9,814 lb (4,452 kg) 122.3 85.8 in (2.18 m) 1981 Boeing 747SP, Lockheed L-1011-250, Lockheed L-1011-500
RB211-524C2 51,500 lbf (229 kN) 9,859 lb (4,472 kg) 119.4 84.8 in (2.15 m) 1980 Boeing 747-200, Boeing 747-300, Boeing 747SP
RB211-524D4 53,000 lbf (240 kN) 9,874 lb (4,479 kg) 122.3 85.8 in (2.18 m) 1981 Boeing 747-200, Boeing 747-300, Boeing 747SP
RB211-524D4-B 53,000 lbf (240 kN) 9,874 lb (4,479 kg) 122.3 85.8 in (2.18 m) 1981 Boeing 747-200, Boeing 747-300,
RB211-524G 58,000 lbf (260 kN) 9,670 lb (4,390 kg) 125 86.3 in (2.19 m) 1989 Boeing 747-400
RB211-524H 60,600 lbf (270 kN) 9,670 lb (4,390 kg) 125 86.3 in (2.19 m) 1990 Boeing 747-400, Boeing 767-300
RB211-524G-T 58,000 lbf (260 kN) 9,470 lb (4,300 kg) 125 86.3 in (2.19 m) 1998 Boeing 747-400, Boeing 747-400F
RB211-524H-T 60,600 lbf (270 kN) 9,470 lb (4,300 kg) 125 86.3 in (2.19 m) 1998 Boeing 747-400, Boeing 747-400F, Boeing 767-300
RB211-535C 37,400 lbf (166 kN) 7,294 lb (3,309 kg) 118.5 73.2 in (1.86 m) 1983 Boeing 757-200
RB211-535E4 40,100 lbf (178 kN) 7,264 lb (3,295 kg) 117.9 74.1 in (1.88 m) 1984 Boeing 757-200, Boeing 757-300, Tupolev Tu-204
RB211-535E4B 43,100 lbf (192 kN) 7,264 lb (3,295 kg) 117.9 74.1 in (1.88 m) 1989 Boeing 757-200, Boeing 757-300, Tupolev Tu-204

See also

Related development

Comparable engines
Related lists

References

Notes
  1. ↑ Rolls-Royce is commonly said to have become bankrupt in 1971. However, strictly speaking only individuals and partnerships can go into bankruptcy in the United Kingdom.
  2. ↑ A snubber (or clapper) is a damper used to prevent blade flutter on narrow-chord fan blades, at the cost of reduced efficiency. Hollow wide-chord blades are more stable and do not need snubbers.
Citations
  1. 1 2 How to Build a Jet Engine (Television production). BBC. 2010.
  2. ↑ William Lazonick and Andrea Prencipe, “Dynamic Capabilities and Sustained Innovation: Strategic Control and Financial Commitment at Rolls-Royce plc,” Industrial and Corporate Change, 14, 3, 2005: 1-42.
  3. ↑ Sometimes called "three-spool".
  4. ↑ 1967 | 2159 | Flight Archive. Flightglobal.com (1967-11-09). Retrieved on 2013-08-16.
  5. ↑ Rolls-Royce. "Three Shaft Engine Design". Archived from the original on 2006-10-16. Retrieved 2007-01-07.
  6. 1 2 3 Pugh, Peter (2001). The Magic of a Name. Icon Books. ISBN 1-84046-284-1.
  7. ↑ Douglas and its DC-10 launch customers American Airlines and United Airlines selected the General Electric CF6 engine for the DC-10. The Pratt & Whitney JT9D was fitted to later variants.
  8. ↑ Bird ingestion testing was, and still is, a FAA requirement for aircraft engines.
  9. ↑ Hooker, 1985.
  10. ↑ Gawer, Annabelle (2010). Platforms, Markets and Innovation. Northampton, MA: Edward Elgar Publishing. p. 313. ISBN 1-84844-070-7.
  11. ↑ "Not much of an Engineer" by Stanley Hooker,
  12. ↑ https://books.google.co.uk/books?id=HZ18AwAAQBAJ&pg=PT228&lpg=PT228&dq=rb211+nimonic&source=bl&ots=VflzZrTqj3&sig=OSiTJ89L4j0ehwWSrWd4rCi2xuc&hl=en&sa=X&ved=0ahUKEwi2lN2rxMbNAhVEKcAKHa6NDM84ChDoAQgyMAM#v=onepage&q=rb211%20nimonic&f=false
  13. ↑ "Red Ink at Rolls-Royce". Time. November 23, 1970. Retrieved 2007-01-06.
  14. ↑ http://hansard.millbanksystems.com/commons/1971/may/10/rb211-engine
  15. ↑ "New Life for TriStar". Time. May 17, 1971. Retrieved 2007-01-06.
  16. ↑ http://filestore.nationalarchives.gov.uk/pdfs/small/cab-128-49-cm-71-15-15.pdf
  17. ↑ Sir Stanley Hooker (1985). Not Much of an Engineer. The Crowood Press. ISBN 1-85310-285-7.
  18. ↑ Andrew Dow (2009). PEGASUS - THE HEART OF THE HARRIER: The History and Development of the World's First Operational Vertical Take-off and Landing Jet Engine. Pen and Sword Aviation. ISBN 184884042X.
  19. ↑ "Type Certificate Data Sheet A23WE, Revision 18" (PDF). FAA. 25 October 2001. Retrieved 2007-01-14.
  20. ↑ https://www.thegazette.co.uk/London/issue/46213/page/2223
  21. ↑ "World Encyclopedia of Aero Engines - 5th edition" by Bill Gunston, Sutton Publishing, 2006, p. vii
  22. 1 2 "World Encyclopedia of Aero Engines - 5th edition" by Bill Gunston, Sutton Publishing, 2006, p.201
  23. ↑ https://www.flightglobal.com/pdfarchive/view/1980/1980%20-%202444.html
  24. ↑ This was later adopted by GE and Pratt and Whitney for their engines.
  25. ↑ "Rolls-Royce standardises on hybrid RB211 after entry success". Flight International. May 6, 1998. Retrieved 2007-01-20.
  26. ↑ "Cathay will re-engine entire 747-400 fleet". Flight International. August 27, 1997. Retrieved 2007-01-20.
  27. ↑ Rolls-Royce. "1904-2004 A Century of Innovation in 100 Facts". Retrieved 2007-01-20.
  28. ↑ "The turbofan engine", page 2. SRM University, Department of aerospace engineering
  29. ↑ "World Encyclopedia of Aero Engines - 5th edition" by Bill Gunston, Sutton Publishing, 2006, p.199
  30. ↑ "Tupolev - Tu-204-120". Flight International. Retrieved 2007-01-20.
  31. ↑ "R-R prepares combustor for low-emissions test". Flight International. August 8, 1998. Retrieved 2007-01-20.
  32. ↑ Rolls-Royce. "RB211-535 Description". Archived from the original on 2006-12-29. Retrieved 2007-01-21.
  33. ↑ Rolls-Royce. "Evolution of the RB211". Retrieved 2007-01-25.
  34. ↑ Rolls-Royce. "Energy Product Areas". Archived from the original on 2007-01-21. Retrieved 2007-01-25.
  35. ↑ "TCDS 1043" (PDF). UK CAA. 12 Oct 1988.
  36. ↑ Rolls-Royce media pack (PDF), Rolls-Royce, retrieved 2008-01-26
Bibliography
  • Gunston, Bill. Development of Piston Aero Engines. Cambridge, England. Patrick Stephens Limited, 2006. ISBN 0-7509-4478-1
  • Hooker, Sir Stanley. Not Much Of An Engineer, Airlife Publishing, 1985. ISBN 1-85310-285-7.
  • Newhouse, John. The Sporty Game: The High-Risk Competitive Business of Making and Selling Commercial Airliners. 1982. ISBN 978-0-394-51447-5
  • Keith, Hayward. Government and British civil aerospace: a case study in post-war technology. 1983. ISBN 978-0-7190-0877-1
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