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Encyclopedia > Napier Sabre

The Sabre was a 24-cylinder sleeve valve piston aircraft engine designed by Major Frank Halford and 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. However, the rapid conversion to jet engines after the war led to the quick demise of the Sabre, as Napier also turned to jets. Sleeve valves are a way of building valves for piston engines that have a number of advantages over the more common poppet valve, used in most engines, as well as disadvantages that have precluded their widespread adoption. ... piston + connecting rod In general, a piston is a sliding plug that fits closely inside the bore of a cylinder. ... 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. ... Major Frank Bernard Halford, (1894–1955), was an aircraft engine designer. ... Napier & Son were one of the most important English aircraft engine manufacturers in the early to mid 20th Century. ... World War II was a truly global conflict with many facets: immense human suffering, fierce indoctrination, and the use of new, extremely devastating weapons such as the atomic bomb. ... An inline engine is an internal-combustion engine with cylinders aligned in one or several rows. ... The horsepower (hp) is the name of several non-metric units of power. ... A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ...

Napier Sabre. Note that the exhaust ports from both banks on one side of the engine are ganged into a single row of pipes. Small amounts of cutaway metal also allows one to see some of the complex gearing needed to drive the sleeves and take power from the two shafts into the prop.
Napier Sabre. Note that the exhaust ports from both banks on one side of the engine are ganged into a single row of pipes. Small amounts of cutaway metal also allows one to see some of the complex gearing needed to drive the sleeves and take power from the two shafts into the prop.

Download high resolution version (2048x1365, 1710 KB)Napier Sabre Aero Engine, taken and sumitted by Paul Maritz (paulmaz) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Download high resolution version (2048x1365, 1710 KB)Napier Sabre Aero Engine, taken and sumitted by Paul Maritz (paulmaz) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...

History

Prior to the Sabre, Napier had been working on large engines for some time. Their most famous was the Lion, which had been a very successful engine between the World Wars and which, in modified form, powered several of the Supermarine designs to the Schneider Trophy in 1923 and 1927. By the late 1920s it was no longer competitive, and work started on replacements. The Lion was a 12-cylinder W-block inline aircraft engine built by Napier & Son starting in 1917, and ending in the 1930s. ... Supermarine was a British ship and aircraft manufacturer. ... The Schneider Trophy (or prize or cup) for seaplanes was announced by Jacques Schneider, a financier, balloonist and aircraft enthusiast, in 1911 with a prize of roughly £1,000. ... 1923 (MCMXXIII) was a common year starting on Monday (link will take you to calendar). ... 1927 (MCMXXVII) was a common year starting on Saturday (link will take you to calendar). ...


They followed the Lion with two new H-block designs: an H-16 engine known as the Rapier, and a H-24 known as the Dagger. The H-block has a compact layout, as it essentially consists of two horizontally opposed inline engines lying one atop another. Since the cylinders are opposed, the motion in one is balanced by the opposite motion in the one on the opposite side, leading to smooth running. However, in these new designs, Napier oddly decided to use air cooling; in service, the rear cylinders proved to be impossible to cool properly, leading to terrible reliability problems. An H engine (or H-block) is an engine configuration in which the cylinders are aligned so that if viewed from the front appear to be in a horizontal letter H. An H engine can be viewed as two flat engines, one atop the other. ... An inline engine is an internal-combustion engine with cylinders aligned in one or several rows. ...


During the 1930s, designers were looking to the future of engine development. Many studies showed the need for engines that could produce 1 hp per cubic inch (50 kW/L), in order to be able to provide the power needed to equip large aircraft which could carry enough fuel for long-range use. In the US this design goal became known as the hyper engine, and it was clear that this sort of performance would not be easy to achieve. A typical large engine of the era, the Pratt & Whitney R-1830 Twin Wasp, developed about 1,200 hp (895 kW) from 1,820 in³ (30 L), so an advance of some 50% would be needed. This called for radical changes, and while many companies tried to build the hyper engine, none were successful. // Events and trends The 1930s were described as an abrupt shift to more radical lifestyles, as countries were struggling to find a solution to the global depression. ... The hyper engine was a hypothetical aircraft engine design, an engine that would be able to deliver 1 horsepower per cubic inch (about 46 kW/L) of engine displacement. ... Pratt & Whitney is an American owned aircraft engine manufacturer whose products are widely used in both civil and military aircraft. ...


In 1927 Harry Ricardo published a seminal study on the concept of the sleeve valve engine. In it he stated that traditional poppet valve engines would likely have a hard time producing much beyond 1,500 hp (1,100 kW), a figure many companies were eyeing for next generation engines. In order to pass this limit, the sleeve valve would have to be used in order to increase volumetric efficiency. Halford's office was next to Ricardo's in London, and while Ricardo started work with Bristol Engines on a whole line of sleeve-valve designs, Halford started work with Napier, using the Dagger as the basis of what would become the most powerful engine in the world. The H-block layout's inherent balance allowed it to run at higher RPM, to deliver more power from a smaller displacement (more bangs per second means more power delivered); the sleeve valve would allow these higher RPMs to be reached. 1927 (MCMXXVII) was a common year starting on Saturday (link will take you to calendar). ... 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. ... Sleeve valves are a way of building valves for piston engines that have a number of advantages over the more common poppet valve, used in most engines, as well as disadvantages that have precluded their widespread adoption. ... poppet valve A poppet valve is the type of valve system used in most piston engines, used to seal the intake and exhaust ports. ... Volumetric efficiency in internal combustion engine design refers to the efficiency with which the engine can move the charge into and out of the cylinders. ... rpm or RPM may mean: revolutions per minute RPM Package Manager (originally called Red Hat Package Manager) RPM (movie) RPM (band), a Brazilian rock band RPM (magazine), a former Canadian music industry magazine In firearms, Rounds Per Minute: how many shots an automatic weapon can fire in one minute On...


The first Sabre engines were ready for testing in January 1938, although at a severely limited 1,350 hp (1,000 kW). By March they were already passing tests at 2,050 hp (1,500 kW), and by June 1940 the first production-ready versions were delivering 2,200 hp (1,640 kW) from their 2,238 in³ (37 L). By the end of the year, they were producing 2,400 hp (1,800 kW). To put this in perspective, the contemporary 1940 Rolls-Royce Merlin II was generating just over 1,000 hp (750 kW), and the most powerful production engines in the world all developed around 1,200 hp (900 kW). 1938 (MCMXXXVIII) was a common year starting on Saturday (link will take you to calendar). ... 1940 (MCMXL) was a leap year starting on Monday (link will take you to calendar). ... The Merlin was a 12 cylinder, 60° V, 27 litre, liquid cooled piston aircraft engine built during World War II by Rolls-Royce. ...


Problems started to appear as soon as volume production started. Up to that point the engines had been hand-assembled by Napier craftsmen, and it proved to be rather difficult to adapt it to assembly line production techniques. In particular, the sleeves tended to fail quite often, seizing the engine in the process. At that time Bristol were developing their own sleeve valve designs, and their Taurus engine had the same bore. At first Bristol refused to work with Napier, but eventually, under intense pressure from the Air Ministry, they relented, and the problems soon disappeared with the addition of Bristol's well-machined sleeves. The Bristol Aeroplane Company (formerly British and Colonial Aeroplane Company) began building primitive Bristol Boxkites in a former tram shed and became famous for the production of the war-time Blenhein and Beaufighter, the Brabazon airliner prototypes, the Britannia and Freighter and the Belvedere and Sycamore helicopters. ... Bristol Taurus engine The Taurus was a 14_cylinder two_row radial aircraft engine, produced by the Bristol Engine Company starting in 1936. ... 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. ...


Quality control also proved to be a serious problem. Engines were often delivered with improperly cleaned castings, broken piston rings, and machine cuttings left inside the engine. Mechanics were constantly overworked trying to keep Sabres running, and during cold weather they had to run them every two hours during the night so that the engine oil wouldn't congeal and prevent the engine starting the next day (unlike 'multigrades' today, the oils available tended to become thick at low temperatures, preventing the Sabre from 'picking-up' when started) These problems took too long to straighten out, and for many the engine started to attain a bad reputation. To make matters worse, mechanics and pilots were unfamiliar with the very different nature of this engine, and tended to blame the Sabre for problems which were caused by incorrect handling. This was all exacerbated by the representatives of the competing Rolls-Royce company, who had their own agenda. Motor oil is a type of liquid oil used for lubrication by various kinds of motors, especially internal combustion engines. ...


The problems were eventually addressed, however, and the engine started to reliably allow higher and higher boost settings. By 1944 the Sabre V was delivering 2,400 hp (1,800 kW) consistently, and the reputation of the engine started to improve. This was the last version to see service, however. The later Sabre VII delivered 3,500 hp (2,600 kW) with a new supercharger, and the final test articles delivered 4,000 hp (3,000 kW). By the end of the war there were several engines of the same power class; the Pratt & Whitney R-4360 Wasp Major was at that time producing about 3,055 hp (2,280 kW), but used over twice the displacement, at 4,360 in³ (71 L). Pratt & Whitney Wasp Major (sectioned) The Pratt & Whitney R-4360 Wasp Major was a large radial piston aircraft engine designed and built during World War II. It was the last of the Wasp family and the culmination of its makers piston engine technology, but the war was over before...


The Sabre's primary use was in the Hawker Typhoon and its derivative, the Tempest. While the former was not the fastest plane in the air, the Sabre engine drove it past anything whilst flying at lower altitudes, where it could reach about 412 mph (663 km/h). At higher altitudes, the thick wing of the Typhoon made it slower, and so it was primarily used as a strike fighter. The later Tempest added a new low-drag wing, and the otherwise similar plane became the fastest propellor-driven fighter of the war, at least for a short time. The Typhoon was a British single-seat fighter aircraft, produced by Hawker Aviation starting in 1941. ... The Hawker Tempest was an RAF fighter aircraft of World War II, an improved derivative of the Hawker Typhoon, and one of the most powerful fighters used in the war. ... A strike fighter is a fighter aircraft used to attack surface targets of high value, including ships. ... A propeller can be seen as a rotating fin in water or a wing in air. ...


Specifications

For Napier Sabre II, the first production version:

Bore by stroke: 5.0 by 4.75 in (127 by 121 mm)
Displacement: 2,238 in³ (36.7L)
Compression ratio: 7 to 1
Power: 2,180 hp (1,630 kW) at 3700 rpm
Weight: 2360 lb (1,070 kg)

For Napier Sabre V (data from Pierre Clostermann's The Big Show): Pierre Clostermann (born February 28, 1921 in Curitiba Brazil) is a French pilot, flying ace, author, engineer, politician, and sport fisherman. ... The Big Show can refer to several things. ...

Rated power: 2,850 hp (2,065 kW) at 3800 rpm and 13 psi (0.9 bar) intake boost
Emergency power: 3,040 hp (2,200 kW) at 4000 rpm

References

  • Sabre Sleeve Valve Engine
LJK Setright: The power to fly: the development of the piston engine in aviation. Allen & Unwin, 1971.
Graham White: Allied Aircraft Piston Engines of World War II . SAE, 1995.


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:
 
WW2 Warbirds: the Hawker Tempest - Frans Bonné (798 words)
But not only the Napier Sabre IV was planned as the powerplant for the Tempest, also the Bristol Centaurus (for the Mk II), Rolls Royce Griffon (Mk II and Mk IV) and Napier Sabre V (Mk VI) were planned to power one of the respective versions.
So when the development of the Napier Sabre IV was discontinued, the Tempest Mk I was dropped but other versions were still ordered.
The inlets for the oil cooler and carburetor were moved from the nose to the wing roots to accomodate a larger radiator.
  More results at FactBites »

 
 

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