IAE SuperFan
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The IAE V2500SF SuperFan was a design study for a high-bypass
geared turbofan The geared turbofan is a type of turbofan aircraft engine, with a gearbox between the fan and the low pressure shaft to spin each at optimum angular velocities. Technology In a conventional turbofan, a single shaft (the "low-pressure" or LP sh ...
derived from the
IAE V2500 The IAE V2500 is a two-shaft high-bypass turbofan engine built by International Aero Engines (IAE) which powers the Airbus A320 family, the McDonnell Douglas MD-90, and the Embraer C-390 Millennium. The engine's name is a combination of the Roma ...
. It was offered as the primary engine option for the
Airbus A340 The Airbus A340 is a long-range, wide-body passenger airliner that was developed and produced by Airbus. In the mid-1970s, Airbus conceived several derivatives of the A300, its first airliner, and developed the A340 quadjet in parallel with ...
in January 1987. Although several customers signed preliminary contracts for this variant, the
International Aero Engines IAE International Aero Engines AG is a Zürich-registered joint venture aero-engine manufacturing company. It was founded during 1983 specifically to develop an aircraft engine to address the 150-seat single aisle aircraft market, the IAE V2500, ...
board decided in April 1987 to stop the development of the SuperFan, which forced
Airbus Airbus SE (; ; ; ) is a European Multinational corporation, multinational aerospace corporation. Airbus designs, manufactures and sells civil and military aerospace manufacturer, aerospace products worldwide and manufactures aircraft througho ...
to partly re-design the A340.


Development program

In July 1986 IAE confirmed to conduct a preliminary design study for a concept examining a high-bypass engine which used the
V2500 The IAE V2500 is a two-shaft high-bypass turbofan engine built by International Aero Engines (IAE) which powers the Airbus A320 family, the McDonnell Douglas MD-90, and the Embraer C-390 Millennium. The engine's name is a combination of the Roma ...
core components. The engine's projected maximum thrust was 28,000–32,000 
lbf The pound of force or pound-force (symbol: lbf, sometimes lbf,) is a unit of force used in some systems of measurement, including English Engineering units and the foot–pound–second system. Pound-force should not be confused with pound-m ...
while having only 80% of the V2500's specific fuel consumption. Prior to that study the IAE shareholders
Rolls-Royce plc Rolls-Royce Holdings plc is a British multinational aerospace and defence company incorporated in February 2011. The company owns Rolls-Royce, a business established in 1904 which today designs, manufactures and distributes power systems for ...
,
Pratt & Whitney Pratt & Whitney is an American aerospace manufacturer with global service operations. It is a subsidiary of Raytheon Technologies. Pratt & Whitney's aircraft engines are widely used in both civil aviation (especially airlines) and military aviat ...
and
MTU Aero Engines MTU Aero Engines AG is a German aircraft engine manufacturer. MTU develops, manufactures and provides service support for military and civil aircraft engines. MTU Aero Engines was formerly known as MTU München. History While the Munich-based en ...
had examined several configuration for a high-bypass engine, including several design features like a variable fan blade pitch, a geared fan or counterrotating concepts (geared as well as ungeared). Review of these design studies in June indicated the design of such a high-bypass engine as a single-rotation, geared fan configuration with variable blade pitch. The fan diameter was expected to range from 108 to 118 in while having a
bypass ratio The bypass ratio (BPR) of a turbofan engine is the ratio between the mass flow rate of the bypass stream to the mass flow rate entering the core. A 10:1 bypass ratio, for example, means that 10 kg of air passes through the bypass duct for ev ...
of 18:1 to 20:1. Availability of the engine was estimated between 1992 and 1994. In December 1986 the V2500 SuperFan was officially offered to Airbus as powerplant for the
Airbus A340 The Airbus A340 is a long-range, wide-body passenger airliner that was developed and produced by Airbus. In the mid-1970s, Airbus conceived several derivatives of the A300, its first airliner, and developed the A340 quadjet in parallel with ...
being developed at that time. With that offer, more design details were revealed. In addition to the V2500 core engine, IAE claimed to be able to derive all further components from proven technology. The RB.211-sized fan was to be driven through a Tyne-technology gearbox. This configuration had a 20:1
bypass ratio The bypass ratio (BPR) of a turbofan engine is the ratio between the mass flow rate of the bypass stream to the mass flow rate entering the core. A 10:1 bypass ratio, for example, means that 10 kg of air passes through the bypass duct for ev ...
and was expected to provide a thrust of 30,000 lbf. Due to the application of existing technology, the costs as well as the risks for the SuperFan development program were appraised lower than those of the competing
CFM56-5 The CFM International CFM56 (U.S. military designation F108) series is a Franco-American family of high-bypass turbofan aircraft engines made by CFM International (CFMI), with a thrust range of . CFMI is a 50–50 joint-owned company of Safran ...
engine. Due to the lower specific fuel consumption and higher thrust rating, the design of the A340 was modified. Compared to the original design's range of 7,000
nautical mile A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters. Historically, it was defined as the meridian arc length corresponding to one minute ( of a degree) of latitude. Today ...
s, the revised version – designated the A340-200 – was projected to have a range up to 8,000 nautical miles with full passenger load. Airbus decided on 26 December 1986 to offer the SuperFan as primary engine option for the A340. In late January,
Boeing The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and product ...
announced that it was studying the SuperFan as an option for the 150-seat 7J7 mid-range aircraft, with the SuperFan mounted under the wings instead of the aft fuselage mounting of the 7J7's baseline engine, the
General Electric GE36 The General Electric GE36 was an experimental aircraft engine, a hybrid between a turbofan and a turboprop, known as an unducted fan (UDF) or propfan. The GE36 was developed by GE Aviation, General Electric Aircraft Engines, with its CFM Internat ...
unducted fan. (The 7J7, not the A340, was actually IAE's primary target aircraft for the SuperFan.) Airbus was also considering the SuperFan for a 175-seat stretched version of its upcoming
Airbus A320 The Airbus A320 family is a series of Narrow-body aircraft, narrow-body airliners developed and produced by Airbus. The A320 was launched in March 1984, Maiden flight, first flew on 22 February 1987, and was introduced in April 1988 by Air F ...
narrowbody aircraft. First voices indicating not only the high risks associated with the new geared turbofan technology but also the potential failure to deliver the SuperFan in time appeared in February 1987. In addition to the fact that the V2500 was not certified yet, not even a
mockup In manufacturing and design, a mockup, or mock-up, is a scale or full-size model of a design or device, used for teaching, demonstration, design evaluation, promotion, and other purposes. A mockup may be a ''prototype'' if it provides at leas ...
of the SuperFan was published, not to mention a test engine. At the same time
Deutsche Lufthansa Deutsche Lufthansa AG (), commonly shortened to Lufthansa, is the flag carrier of Germany. When combined with its subsidiaries, it is the second- largest airline in Europe in terms of passengers carried. Lufthansa is one of the five founding m ...
and Airbus signed a preliminary contract for 15 orders and 15 options of the A340 with SuperFan engines. First deliveries were agreed for April 1992. Reinhardt Abraham (vice chairman of the
Lufthansa Deutsche Lufthansa AG (), commonly shortened to Lufthansa, is the flag carrier of Germany. When combined with its subsidiaries, it is the second- largest airline in Europe in terms of passengers carried. Lufthansa is one of the five founding m ...
board) stated that Lufthansa acknowledges the risks connected to the SuperFan program but got binding guarantees by IAE for the performance data and the delivery date. He also described the SuperFan as a rather conservative technology compared to the several
Propfan A propfan, also called an open rotor engine, or unducted fan (as opposed to a ducted fan), is a type of aircraft engine related in concept to both the turboprop and turbofan, but distinct from both. The design is intended to offer the speed an ...
programs that gained a lot of attention at that time. In contradiction to that, officials of
Douglas Aircraft The Douglas Aircraft Company was an American aerospace manufacturer based in Southern California. It was founded in 1921 by Donald Wills Douglas Sr. and later merged with McDonnell Aircraft in 1967 to form McDonnell Douglas; it then operated as ...
– responsible for the A340 competitor
MD-11 The McDonnell Douglas MD-11 is an American tri-jet wide-body airliner manufactured by American McDonnell Douglas (MDC) and later by Boeing. Following DC-10 development studies, the MD-11 program was launched on December 30, 1986. Assembly of t ...
– questioned the timetable for the SuperFan. In addition to the missing demonstrator and test engine, the feasibility of the required 20,000 SHP gearbox was challenged. Competitor
CFM International CFM International is a 50/50 Franco-American joint venture between GE Aviation and Safran Aircraft Engines (formerly known as Snecma). It was formed to build and support the CFM56 series of turbofan engines. The company is the world’s leading s ...
even completely ruled out the possibility to develop the SuperFan concept in the remaining time until 1992. Despite these concerns, Airbus was able to announce at a meeting of the supervisory board on 13 March 1987 a total of 104 commitments from nine customers for their
A330 The Airbus A330 is a wide-body aircraft developed and produced by Airbus. Airbus conceived several derivatives of the A300, its first airliner in the mid-1970s. Then the company began development on the A330 twinjet in parallel with the A340 ...
/A340 program. On 3 April,
Northwest Airlines Northwest Airlines Corp. (NWA) was a major American airline founded in 1926 and absorbed into Delta Air Lines, Inc. by a merger. The merger, approved on October 29, 2008, made Delta the largest airline in the world until the American Airlines ...
announced their commitment for up to 20 A340s with SuperFan engines. Of the now-ten customers for the A330/A340 program, eight ordered the A340 with SuperFan engines; in addition to
Lufthansa Deutsche Lufthansa AG (), commonly shortened to Lufthansa, is the flag carrier of Germany. When combined with its subsidiaries, it is the second- largest airline in Europe in terms of passengers carried. Lufthansa is one of the five founding m ...
, the list of SuperFan customers included
Finnair Finnair ( fi, Finnair Oyj, sv, Finnair Abp) is the flag carrier and largest airline of Finland, with its headquarters in Vantaa on the grounds of Helsinki Airport, its hub. Finnair and its subsidiaries dominate both domestic and internationa ...
, UTA,
Sabena The ''Societé anonyme belge d'Exploitation de la Navigation aérienne'' (French; ), better known by the acronym Sabena or SABENA, was the national airline of Belgium from 1923 to 2001, with its base at Brussels National Airport. After its ba ...
, and
Alitalia Alitalia - Società Aerea Italiana Società per azioni, S.p.A., operating as Alitalia (), was an Italian airline which was once the flag carrier and largest airline of Italy. The company had its head office in Fiumicino, Metropolitan City of ...
. In a board meeting on 7 April 1987, however, the SuperFan program was officially announced as "indefinitely delayed". No official statement was made after that decision, but Ralph Robins, managing director of Rolls-Royce and board member of IAE, indicated problems with the low-pressure system posed a serious threat to deliver the engine in 1992. Airbus was formally notified about the technical risk in mid-March. He insisted that the problems IAE faced at the same time with the high-pressure compressor of the V2500 were not connected to the SuperFan delay. IAE also contended that the SuperFan was not more than an engineering study and they never committed to develop that engine. Nevertheless, further studies of the geared turbofan concept were announced. In contradiction to IAE's understanding of the SuperFan as an engineering study, the vice chairman of the Lufthansa board, Reinhardt Abraham, made clear that the Lufthansa board had received verbal as well as written confirmations that the SuperFan was a fixed development program. He admitted that Lufthansa had realized the risks in the SuperFan program but had relied on the experience and reputation of the IAE shareholding companies. When asked for the delay's reason, he revealed that in a meeting at the beginning of 1987 IAE presented several technical problems that had arisen: not only the gearbox was mentioned, but also the variable-pitch mechanism and the bypass outlet duct. But in Abraham's opinion these problems could have been solved by investing more, he blamed the problems with the V2500 high-pressure compressor as the trigger to cancel the SuperFan. This assumption is supported by the fact, that a core engine which is optimized for a conventional turbofan, can not be used for a geared turbofan without extensive modifications to prevent
compressor surge A compressor stall is a local disruption of the airflow in the compressor of a gas turbine or turbocharger. A stall that results in the complete disruption of the airflow through the compressor is referred to as a compressor surge. The severity of t ...
during low thrust ratings. Lufthansa's engineers recommended against buying the A340 because of doubts of the engine's readiness by 1992, but they were overruled by Lufthansa chairman Heinz Ruhnau with the backing of
Franz Josef Strauss Franz Josef Strauss ( ; 6 September 1915 – 3 October 1988) was a German politician. He was the long-time chairman of the Christian Social Union in Bavaria (CSU) from 1961 until 1988, member of the federal cabinet in different positions between ...
, who was both a Lufthansa supervisory board member and the Airbus chairman. When it was clear that the SuperFan would not be available, Airbus decided to offer the CFM56-5C on the A340. In order to achieve comparable performance data to the SuperFan-powered version, the wingspan was extended by 2.6 meters to allow a larger fuel capacity.


Design features

The fan diameter of the SuperFan was planned to be 107 in (2.72 m), resulting in a
nacelle A nacelle ( ) is a "streamlined body, sized according to what it contains", such as an engine, fuel, or equipment on an aircraft. When attached by a pylon entirely outside the airframe, it is sometimes called a pod, in which case it is attached ...
with a diameter of 120 in (3.05 m) made from
composite materials A composite material (also called a composition material or shortened to composite, which is the common name) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or ...
. To ensure a good performance also in partload ratings and to support the
thrust reverser Thrust reversal, also called reverse thrust, is the temporary diversion of an aircraft engine's thrust for it to act against the forward travel of the aircraft, providing deceleration. Thrust reverser systems are featured on many jet aircraft ...
, a variable-pitch mechanism for the 18 fan blades would have been installed. The blades itself were designed as hollow
titanium Titanium is a chemical element with the symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in ...
blades. The fan blades would be shrouded by a cowling, but unlike with normal turbofans, the fan cowling would not extend backward, and the rest of the engine would be enclosed in a separate, slimmer cowling. The fan gearbox with a gear ratio of 3:1 would have been derived from the Rolls-Royce Tyne gearbox, so it can be concluded that the SuperFan gearbox would have been realised as a planetary design with single helical gearing.


Specifications


See also


References


Bibliography

* * * * * * * * * * {{Joint development aeroengines High-bypass turbofan engines 1980s turbofan engines Geared turbofan engines