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Encyclopedia > Napier Nomad

The Nomad was a complex Diesel cycle aircraft engine from Napier & Son of the UK. The Nomad used a turbine to recover power from the exhaust of the otherwise conventional Diesel engine, resulting in a specific fuel consumption that remains unmatched today, 50 years later. Image File history File links File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... The diesel cycle is the combustion process of a type of internal combustion engine in which the burning of the fuel is triggered not by a spark plug as in the Otto cycle, but rather by the heat generated in compressing the fuel-air mixture. ... The term aircraft engine, for the purposes of this article, refers to aircraft reciprocating, or rotary, internal combustion engines as opposed to jet engines or turboprops. ... Napier & Son were one of the most important English aircraft engine manufacturers in the early to mid 20th Century. ... WWII era steam turbine used for ship propulsion. ... Specific fuel consumption, often shortened to SFC, is an engineering term that is used to describe the fuel efficiency of an engine design. ...

Contents


History

In 1945 the Air Ministry asked for proposals for a new 6,000 horsepower (4,500 kW) class engine with good economy. Curtiss-Wright was designing an engine of this sort of power known as the "turbo-compound", but Sir Harry Ricardo, one of Britain's great engine designers, suggested that the most economical combination would be a similar design using a diesel two-stroke in place of the Curtiss's gasoline engine. The Air Ministry was formerly a department of the United Kingdom Government, established in 1918 with the responsibility of managing the affairs of the (then newly formed) Royal Air Force. ... The horsepower (hp) is the name of several non-metric units of power. ... The Curtiss-Wright Corporation was once a leading aircraft manufacturer of the United States, but has since become a component manufacturer, specializing in actuators, controls, valves, and metal treatment. ... Sir Harry Ricardo (1885-1974) was one of the foremost engine designers and researchers in the early years of the development of the internal combustion engine. ...


Prior to World War II Napier had licensed the Junkers Jumo 204 Diesel design to set up production in the UK as the Napier Culverin, however the start of the war made the Sabre all-important and work on the Culverin was stopped. In response to the Air Ministry requirements they dusted off this work, combining two enlarged Culverins into an H-block similar to the Sabre, resulting in a massive 75 litre design. Markets for an engine of this size seem limited however, and instead they returned to the original Culverin-like horizontally opposed 12 cylinder design, resulting in the Nomad. World War II was a truly global conflict with many facets: immense human suffering, fierce indoctrinations, and the use of new, extremely devastating weapons such as the atom bomb World War II, also known as the Second World War, was a mid-20th-century conflict that engulfed much of the... The Junkers Jumo 205 aircraft engine was the most famous of a series of diesel engines that were the first, and for more than half a century, the only successful diesel aircraft engines. ... The Sabre was a 24-cylinder sleeve valve piston aircraft engine built by Napier & Son during WWII. It was one of the most powerful piston aircraft engines in the world, especially for inline designs, developing over 3,500 horsepower (2,200 kW) in its later versions. ...


Design

The Nomad design was incredibly complex, essentially two engines in one. One was a supercharged Diesel similar to the Culverin. Below this was a complete turboprop engine, based on their Naiad design. The output of the turboprop was geared to a shaft running inside the Diesel's, driving the front propeller of a contra-rotating pair. As if that were not enough, during takeoff additional fuel was dumped into the rear turbine stage for additional power, and turned off once the plane was cruising. A supercharger (also known as a blower, a positive displacement pump or a centrifugal pumper) is a gas compressor used to pump air into the cylinders of an internal combustion engine. ... A diagram showing how a turboprop works. ...


The compressor and turbine assemblies of the Nomad 1 were tested during 1948, and the complete unit was run in October 1949. The prototype was installed in the nose of a Avro Lincoln bomber for testing, and first flew in 1950. In total the Nomad 1 ran for just over 1,000 hours, and proved to be rather temperamental, but when running properly it could produce 3000 hp (2,200 kW) and 320 lbf (1.4 kN) thrust. It had a specific fuel consumption (sfc) of 0.36 lb/(hp·h) (0.22 kg/(kW·h)). Compressor has several meanings: A gas compressor is a mechanical device that takes in a gas and increases its pressure by squeezing a volume of it into a smaller volume. ... WWII era steam turbine used for ship propulsion. ... Avro Lincoln The Avro Lincoln was a British 4-engined heavy bomber of World War II, developed from the Avro Lancaster and initially known as the Lancaster IV and V, becoming the Lincoln B1 and B2 respectively. ... A bomber is a military aircraft designed to attack ground targets, primarily by dropping bombs. ... Specific fuel consumption, often shortened to SFC, is an engineering term that is used to describe the fuel efficiency of an engine design. ...


Even before the Nomad 1 was running, its replacement, the Nomad 2, had already been designed. In this version an extra compressor stage was added, replacing the original supercharger. This stage was driven by an additional stage in the turbine, so the system was now more like a turbocharger and the compressed air for the Diesel was no longer "robbing" power. In addition the propeller shaft from the turbine was eliminated, and geared using a hydraulic clutch into the main shaft. The result was smaller and considerably simpler, a single engine driving a single propeller. Turbocharger Cut-away A turbocharger is a compressor used in internal-combustion engines to increase the power output of the engine by increasing the mass of oxygen entering the engine. ... A clutch is a subcomponent of an engines transmission designed to allow engagement or disengagement of the engine to the gearbox or whatever apparatus is being driven. ...


While the Nomad 2 was undergoing testing, a prototype Avro Shackleton was lent to Napier as a testbed. The engine proved bulky, like the Nomad 1 before it, and in the meantime several dummy engines were used on the Shackleton for various tests. By 1954 interest in the Nomad was dropping, and after the only other project based on it was cancelled, work on the engine was ended in April 1955, after an expenditure of £5.1 million. The Shackleton was a piston-engined military aircraft built by Avro and named after the polar explorer Sir Ernest Shackleton. ...


Specifications

For Nomad 2:

Layout: twelve-cylinder, two-row horizontally opposed
Bore: 6 in (152 mm)
Stroke: 7.375 in (187 mm)
Displacement: 2502 in³ (41 L)
Compression ratio: 8:1 (Engine) Compressor Max Press ratio 8.25:1 (12 Stage)
Power: 3,135 ehp (2,338 kW) max take-off at 89 psia (614 kPa) including thrust power from turbine
Weight: 3,580 lb (1630 kg)
SFC: 0.345 lb/(hp·h) (0.210 kg/(kW·h))

External links

The Nomad Proposal


Lists of Aircraft | Aircraft manufacturers | Aircraft engines | Aircraft engine manufacturers This list of aircraft is sorted alphabetically, beginning with the name of the manufacturer (or, in certain cases, designer). ... This is a list of aircraft manufacturers (in alphabetic order). ... List of aircraft engines - Wikipedia /**/ @import /skins-1. ... This is a list of aircraft engine manufacturers both past and present. ...


Airports | Airlines | Air forces | Aircraft weapons | Missiles | Timeline of aviation This is a list of airlines in operation. ... This is a list of Air Forces, sorted alphabetically by country. ... This is a list of aircraft weapons, past and present. ... Below is a list of (links to pages on) missiles, sorted alphabetically by name. ... This is a timeline of aviation history. ...


  Results from FactBites:
 
Napier Nomad (538 words)
The Nomad used a turbine to recover power from the exhaust of the otherwise conventional Diesel engine, resulting in a specific fuel consumption that remains unmatched today, 50 years later.
Prior to World War II Napier had licensed the Junkers Jumo 204[?] Diesel design to set up production in the UK as the Napier Culverin[?], however the start of the war made the Sabre all-important and work on the Culverin was stopped.
While the Nomad 2 was undergoing testing, a prototype Avro Shackleton[?] was lent to Napier as a testbed.
  More results at FactBites »

 
 

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