Rolls-Royce RB211

Rolls-Royce RB.211

RB211 powered Lockheed L-1011

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. RB stands for "Rolls Barnoldswick", a major facility of Rolls-Royce plc.

Rolls-Royce engines had traditionally had numeric names while in testing and then were assigned the name of a British river on delivery. The use of river names is intended to reflect the nature of jet engines...a steady flow of power rather than the pulses of a piston engine. This did not happen with the RB.211, however when a new series evolved out of the RB.211 line it would be known as the Rolls-Royce Trent.

General

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 Lockheed 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. 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 cancelled in favour of the RB.211 programme.

Finalisation of design

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.

To this they added one totally new piece of technology, a fan stage built of the new carbon fibre materials developed at 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.

Combining the three-spool layout of the RB.203, with the size and power of the RB.178, and the new carbon fibre fan stage resulted in the new and highly advanced RB.211. Lockheed jumped at the chance to work with the new engine, which they felt 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 problematical, 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 nationalised by the then-Conservative government of Edward Heath. They were eventually able to deliver their first production machines in the early 1970s.

At the time the bailout loans, and the use of nationalisation 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 British Airways 747-400 powered by the RB211-524G

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.

The RB211-524G/H-T powers the Boeing 747-400

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, benefitting from Trent's improved performance.

RB211-535 series

This is essentially a scaled down version of the -524. Its thrust range spans from 37,000 to 43,100 pounds-force (165 to 192 kN). It powers Boeing 757 and the Russian Tupolev Tu-204 airliner. It is 180-minute ETOPS rated. The later series shares common features with the later series -524 such as wide-chord fan and FADEC. 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.