Rolls-Royce RB211
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The Rolls-Royce RB.211 family is a family of high-bypass turbofan aircraft engines made by Rolls-Royce capable of generating 37,400 to 60,600 pounds-force (166 to 270 kilonewtons) thrust. Originally developed to power the Lockheed L-1011, the engine has since gone on to power almost all modern large airliners in one version or another.
Rolls-Royce engines had traditionally bore numeric names during development and then were assigned the name of a British river on delivery. The use of river names was introduced with the earliest Rolls jet engines to reflect their nature, a steady flow of power rather than the pulses of a piston engine. Such a name was not assigned to the RB.211, however when a new series evolved out of the RB.211 line it would be known as the Rolls-Royce Trent. RB stands for "Rolls Barnoldswick", the latter a major ex-Rover facility purchased by Rolls Royce.
History
In the mid-1960s American Airlines announced a contest for a new trans-Atlantic aircraft with a focus on low-cost per-seat operations. Both Douglas and Lockheed responded with designs, the DC-10 and L-1011 respectively. Both designs were similar, using the minimum number of engines legally allowed, three, seating passengers in a widebody layout with two aisles, and providing enough range to serve all of North America as well as routes from the US eastern seaboard to various points in Europe and the Caribbean.
Both designs also turned to new engine designs to offer the maximum possible fuel economy. Engines were undergoing a period of rapid advance due to the introduction of the "ultra-high bypass" concept, and newer engines were so much more efficient than older ones that companies without such a design would be at a serious disadvantage.
Finalisation of design
Rolls-Royce jumped at the chance to build such a design, combining features of several engines then under development. Rolls 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 RB.178. This work was later developed for the 47,500 lbf (211 kN) thrust RB.207 to be used on the Airbus A300, before it was canceled in favor of the RB.211 program.
Meanwhile Rolls was also working on a series of "three-spool" designs, which promised to deliver higher efficiencies. In the three-spool design three turbines spin separate 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 the "right" speed, the three 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 intended to replace the famous Rolls-Royce Spey known as the RB.203.
The eventual RB.211 design was essentially a combination of these two concepts, the large high-power high-bypass design from the RB.207 and the three-spool design of the RB.203. To this they added one totally new piece of technology, a fan stage built of the new carbon fibre materials developed at RAE Farnborough. The weight savings were considerable over a similar fan made of steel, and would have resulted in the RB.211 outperforming anything in the air in terms of power-to-weight ratio.
Lockheed felt the new engine would offer a distinct advantage over the otherwise similar DC-10 product. However the RB.211's complexity required a lengthy testing period. Things went further astray when the new fan stage, after passing every other test, shattered into pieces when a chicken was fired into it at high speed. A short-term solution, replacing the fan blading with titanium, also turned out to be problematic, with the discovery that only one side of the titanium billet was of the right metallurgical quality for blade fabrication.
Bankruptcy and aftermath
In 1971, after massive development costs associated with the RB.211, Rolls-Royce went bankrupt, seriously jeopardizing the L-1011 Tristar program (and ultimately delaying its introduction by several years). The company was "saved" by a loan from the US government arranged by Lockheed, a highly contentious issue in both countries, and Rolls-Royce was nationalized by the then-Conservative government of Edward Heath.
Kenneth Keith, the new chairman who had been put to rescue the company, convinced Stanley Hooker to come out of retirement and return to Rolls, Hooker's first job starting in 1937. As technical director he led a team of other retirees to fix the problems, and they were able to deliver their first production versions in the early 1970s. Hooker was knighted for his role in 1974.
At the time the bailout loans, and the use of nationalization by a Conservative administration, were a matter of serious public debate, but the matter soon slipped from attention. The RB.211 series has since matured into one of the most reliable engines in history. Although originally designed for the L.1011 and similar aircraft, improvements in quality and power have allowed it to meet a number of mission profiles and performance needs, powering at least some versions of almost every large passenger plane since the 1970s.
Versions
The family is divided into three distinct series:
RB211-22 series
This is the first of the whole series which first saw service in 1972. It was specifically designed for the Lockheed L-1011. Its thrust rating is 42,000 lbf (169 kN). Being the pioneer three-shaft engine it underwent difficult gestation. However, it improved during service and matured into a reliable engine.
RB211-524 series
A development of the -22, it featured a very mature design. Its thrust rating is 50,000 to 60,600 pounds-force (222 to 270 kN). It was first fitted into Boeing 747 in 1977. Its excellent service record led it to be fitted to the improved Lockheed L-1011 in 1981.
An improved version, -524G rated at 58,000 pounds-force (258 kN) and -524H rated at 60,600 pounds-force (270 kN), featuring FADEC, was offered with Boeing 747-400 and Boeing 767. It is ETOPS 180-minutes rated for the 767. The -524G and H is the first to feature the wide-chord fan, which increases efficiency, reduces noise and gives added protection against foreign object damage. This was later adopted by GE and Pratt and Whitney for their engines.
Further improvements led to the -524G/H-T fitted to the 747-400 which is essentially remanufactured -524G and -524H fitted with the core turbomachinery of Rolls-Royce Trent, benefiting from Trent's improved performance.
RB211-535 series
In early 80's, to produce a powerplant for the forthcoming Boeing 757, Rolls-Royce derived the RB211-535C from the -22, by cropping the fan and removing the first IP compressor stage. A relatively small number of these were installed on production aircraft.
However, following the launch of the Pratt & Whitney PW2000, Rolls-Royce were put under pressure by Boeing to supply a more competitive engine. So, using the more advanced -524 core as a basis, the company produced the RB211-535E4. As well as a featuring a destaged IP compressor, the E4 was the first engine to incorporate a wide chord, unsnubbered, fan to improve efficiency. After being certified for the -757 , a version of the E4 was developed for the Russian Tupolev Tu-204 airliner. The -E4 is 180-minute ETOPS rated. Later engines incorporate some features (e.g. FADEC) from improved models of the -524.
The 535E-4 was proposed by Boeing for re-engining the B-52H Stratofortress, replacing the aircraft's eight TF33s with four of the turbofans.
Leading Particulars
| RB211 Engine Family : Leading Particulars | ||||
|---|---|---|---|---|
| Engine | Static Thrust (lbf) | Basic Engine Weight (lb) | Length (in) | Fan Diameter (in) |
| RB211-22B | 42000 | 9195 | 119.4 | 84.8 |
| RB211-524B | 50000 | 9814 | 119.4 | 84.8 |
| RB211-524B4 | 50000 | 9814 | 122.3 | 85.8 |
| RB211-524C2 | 51500 | 9859 | 119.4 | 84.8 |
| RB211-524D4 | 53000 | 9874 | 122.3 | 85.8 |
| RB211-524D4-B | 53000 | 9874 | 122.3 | 85.8 |
| RB211-524G | 58000 | 9670 | 125 | 86.3 |
| RB211-524H | 60600 | 9670 | 125 | 86.3 |
| RB211-524G-T | 58000 | 9470 | 125 | 86.3 |
| RB211-524H-T | 60600 | 9470 | 125 | 86.3 |
| RB211-535C | 37400 | 7294 | 118.5 | 73.2 |
| RB211-535E4 | 40100 | 7264 | 117.9 | 74.1 |
| RB211-535E4B | 43100 | 7264 | 117.9 | 74.1 |