The Rolls-Royce RB3011 (previously designated RB2011) is a prototype
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 a ...
engine in development by
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 ...
. The design is also known as an "open rotor" engine.
Design and development
The RB3011 is designed for the 180–300 passenger aircraft (e.g.
Boeing 737
The Boeing 737 is a narrow-body aircraft produced by Boeing at its Boeing Renton Factory, Renton Factory in Washington (state), Washington.
Developed to supplement the Boeing 727 on short and thin routes, the twinjet retains the Boeing 707, 7 ...
or
Airbus A320
The Airbus A320 family is a series of narrow-body airliners developed and produced by Airbus.
The A320 was launched in March 1984, first flew on 22 February 1987, and was introduced in April 1988 by Air France.
The first member of the famil ...
). The RB3011 was renamed from RB2011, because Rolls-Royce employees kept confusing the ''2011'' with the expected service entry date.
Rolls-Royce bought the
Allison Engine Company
The Allison Engine Company was an American aircraft engine manufacturer. Shortly after the death of James Allison in 1929 the company was purchased by the Fisher brothers. Fisher sold the company to General Motors, which owned it for most of it ...
in 1995, and has studied the
Pratt & Whitney/Allison 578-DX propfan engine built in the 1980s.
The engine has two
contra-rotating
Contra-rotating, also referred to as coaxial contra-rotating, is a technique whereby parts of a mechanism rotate in opposite directions about a common axis, usually to minimise the effect of torque. Examples include some aircraft propellers, res ...
rotors (fans) on the outside of the engine
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 ...
, either at the front of the assembly ("tractor") or at the rear ("pusher"). Both pusher and tractor open rotor designs form part of Rolls-Royce's long-term "15-50" vision, which is examining various architectures to tackle the 150 seat-aircraft market. Within 15-50 group – named for specific fuel consumption reductions of 15–50% compared with current generation engines – there are various options based on technology availability and maturity.
The open rotor design is known to have increased noise compared to normal turbofan engines, where noise is contained by the engine duct. The forward rotor is larger in diameter than the rear rotor, to avoid problems with
eddies
In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid is in a turbulent flow regime. The moving fluid creates a space devoid of downstream-flowing fluid on the downstream side of the object. Fluid b ...
from the forward rotor tips. The rotors are powered by the engine shaft via an
epicyclic gearbox
An epicyclic gear train (also known as a planetary gearset) consists of two gears mounted so that the center of one gear revolves around the center of the other. A carrier connects the centers of the two gears and rotates the planet and sun gea ...
. These produce a large amount of heat.
In late 2008, the RB3011 was considered a contender for the powerplant of the
Irkut MS-21. Rolls-Royce felt it could develop and certify the engine before the aircraft's planned (at the time) certification in the first quarter of 2015.
The engine has been tested at the
Aircraft Research Association in
Bedford
Bedford is a market town in Bedfordshire, England. At the 2011 Census, the population of the Bedford built-up area (including Biddenham and Kempston) was 106,940, making it the second-largest settlement in Bedfordshire, behind Luton, whilst ...
,
Bedfordshire
Bedfordshire (; abbreviated Beds) is a ceremonial county in the East of England. The county has been administered by three unitary authorities, Borough of Bedford, Central Bedfordshire and Borough of Luton, since Bedfordshire County Council ...
. Wind-tunnel testing has taken place at DNW in
Marknesse in the Netherlands.
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It is hoped to reduce the fuel consumption
A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but ...
of an aircraft, compared to those with normal turbofan engines, by up to 30%. This is the main reason for choosing this design of engine. Certification is planned for 2017–2018, with market entry with airlines by 2020.
See also
References
External links
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{{Rolls-Royce plc aeroengines
Rolls-Royce aircraft gas turbine engines
Propfan engines
Proposed engines