Inline engine (aeronautics)

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A Mercedes D.II inline engine on display Daimler D II.jpg
A Mercedes D.II inline engine on display

In aviation, an inline engine is a reciprocating engine with banks of cylinders, one behind another, rather than rows of cylinders, with each bank having any number of cylinders, although more than six is uncommon. The major reciprocating-engine alternative configuration is the radial engine, where the cylinders are placed in a circular or "star" arrangement.

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The term "inline" is used somewhat differently for aircraft engines than automotive engines. For automotive engines, the term ‘inline’ refers only to straight engines (those with a single bank of cylinders). But for aircraft, ‘inline’ can also refer to engines which are not of the straight configuration, such as v, w, or horizontally opposed.[ citation needed ]

Inline engine configurations

Straight
Engines with a single bank of cylinders which can be arranged at any angle but typically upright or inverted, (e.g. upright ADC Cirrus, inverted de Havilland Gipsy Major).
V
Engines with two banks of cylinders with less than 180° between them driving a common crankshaft, typically arranged upright or inverted (e.g. upright Liberty L-12, inverted Argus As 410). [1] [2]
A W-12 Napier Lion engine LionEngine.jpg
A W-12 Napier Lion engine
O or Horizontally Opposed
Engines with two banks of cylinders arranged at 180° to each other driving a common crankshaft, almost universally mounted with banks horizontal for aircraft use, or with crankshaft vertical for helicopter use, (e.g. horizontally mounted Continental O-190, vertically mounted Franklin 6ACV-245).
An H-24 Napier Dagger engine on display at the Royal Air Force Museum Hendon. NapierDagger.JPG
An H-24 Napier Dagger engine on display at the Royal Air Force Museum Hendon.
W
Engines with three banks driving a common crankshaft, arranged so that first and last banks are 180°or less apart, (e.g. upright Lorraine 12Eb, inverted Napier Lioness). [3] [4]
X
Multiple bank engines with four banks arranged around a common crankshaft, usually spaced evenly, (e.g. evenly spaced Rolls-Royce Vulture, unevenly spaced Napier Cub).
A cutaway Jumo 205 2-stroke opposed piston diesel engine Jumo205 cutview.JPG
A cutaway Jumo 205 2-stroke opposed piston diesel engine
Fan
Engines with more than three banks with 180° or less between first and last bank, akin to W engines.

Note: Fan engines with single cylinder banks, typically from Anzani, are usually regarded as variants of the Radial engine.

A Bugatti U-16 engine King-Bugatti.jpg
A Bugatti U-16 engine
U
Engines with two banks of cylinders side by side driving separate crankshafts geared to a single output, (e.g. Bugatti U-16).
H
Engines with four banks of cylinders driving two crankshafts geared to a single output, in effect, two Opposed engines coupled together and mounted either horizontally or vertically, (e.g. horizontally Napier Sabre, vertically Napier Dagger).
Opposed piston
Two-stroke engines, typically compression ignition/Diesel, with a single bank of cylinders driving two crankshafts where the pistons travel towards each other forming single combustion chambers, (e.g. Jumo 207).
Deltic: Engines with three banks of opposed piston cylinders arranged in a triangle with three crankshafts geared to drive a single output,(e.g. Napier Deltic)
Rhomboidal: Engines with four or more banks of opposed piston cylinders arranged in a square with four crankshafts geared to drive a single output,(e.g. Jumo 223)

Note: There is no theoretical limit to the number banks in an opposed piston engine, limitations include cost, complexity and reliability.

Multiple bank
Engines with more than two banks, arranged around a common axis and/or crankshaft with more than 180° between first and last banks.
Star: Multiple bank engines with an even number of banks (more than four) arranged around a common axis and/or driving a common crankshaft with more than 180° between first and last banks, (e.g. Jumo 222, Dobrynin VD-4K).
A Junkers Jumo 222 multibank aviation engine, four cylinders per bank. Jumo 222 E links.JPG
A Junkers Jumo 222 multibank aviation engine, four cylinders per bank.
Inline Radial: Multiple bank engines, usually liquid-cooled, with an odd number of banks (three or more) arranged around a common axis and/or driving a common crankshaft with more than 180° between first and last banks, (e.g. air-cooled Armstrong Siddeley Deerhound, liquid-cooled BMW 803).

Note The BMW 803 is not only an inline radial engine but is also a coupled engine with two engines arranged back to back on a common axis driving separate co-axial propellers through a common gearbox.

Inverted engine

Argus As 10 inverted air-cooled V8 engine Argus AS 10 Aviaticum.JPG
Argus As 10 inverted air-cooled V8 engine

An upright engine has the cylinder heads directly above the crankshaft. By contrast an inverted engine has the cylinder heads directly beneath it. In the inverted V layout, the cylinders angle downwards instead of upwards.

For an aero engine, advantages of the inverted layout include improved access to cylinder heads and manifolds for the ground crew, [5] [6] [7] having the centre of mass of a multi-bank engine lower in the engine and, for engines mounted in the nose, improved visibility for the pilot and placing the widest part of a multi-bank engine closer to the midline of the fuselage, which is typically its widest point. [5]

The Hirth HM 60 four-cylinder inverted inline engine was introduced in 1924, and inverted designs saw increasing popularity through the late 1920s and 30s. Widespread examples included the inline de Havilland Gipsy Major used in the de Havilland Tiger Moth, and the inverted-V Daimler-Benz DB 601 used in the Messerschmitt Bf 109.

Related Research Articles

Radial engine Reciprocating engine with cylinders arranged radially from a single crankshaft

The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is called a "star engine" in some other languages.

Aircraft engine Engine designed for use in powered aircraft

An aircraft engine, often referred to as an aero engine, is the power component of an aircraft propulsion system. Most aircraft engines are either piston engines or gas turbines, although a few have been rocket powered and in recent years many small UAVs have used electric motors.

Straight engine Type of engine

The straight or inline engine is an internal combustion engine with all cylinders aligned in one row and having no offset. Usually found in four, six and eight cylinder configurations, they have been used in automobiles, locomotives and aircraft, although the term in-line has a broader meaning when applied to aircraft engines, see Inline engine (aviation).

The engine configuration describes the fundamental operating principles by which internal combustion engines are categorized.

Flat engine Combustion engine using pistons facing to the sides on a common crankshaft

A flat engine, also known as a horizontally opposed engine, is a piston engine where the cylinders are located on either side of a central crankshaft. A flat engine should not be confused with the opposed-piston engine, in which each cylinder has two pistons sharing a central combustion chamber.

Straight-twin engine Inline piston engine with two cylinders

A straight-twin engine, also known as an inline-twin, vertical-twin, or parallel-twin, is a two-cylinder piston engine whose cylinders are arranged in a line along a common crankshaft.

Napier Deltic Opposed-piston engine used in marine, firefighting and BR locomotive applications

The Napier Deltic engine is a British opposed-piston valveless, supercharged uniflow scavenged, two-stroke diesel engine used in marine and locomotive applications, designed and produced by D. Napier & Son. Unusually, the cylinders were disposed in a three-bank triangle, with a crankshaft at each corner of the triangle.

Opposed-piston engine Combustion engine using disks compressing fuel in the same cylinder

An opposed-piston engine is a piston engine in which each cylinder has a piston at both ends, and no cylinder head. Petrol and diesel opposed-piston engines have been used mostly in large-scale applications such as ships, military tanks, and factories. Current manufacturers of opposed-piston engines include Fairbanks-Morse, Cummins and Achates Power.

Junkers Jumo 205

The Junkers Jumo 205 aircraft engine was the most famous of a series of aircraft diesel engines that were the first, and for more than half a century, the only successful aviation diesel powerplants. The Jumo 204 first entered service in 1932. Later engines of this type comprised the experimental Jumo 206 and Jumo 208, with the Jumo 207 produced in some quantity for the Junkers Ju 86P and -R high-altitude reconnaissance aircraft, and the 46-meter wingspan, six-engined Blohm & Voss BV 222 Wiking flying boat. All three of these variants differed in stroke and bore and supercharging arrangements. In all, more than 900 of these engines were produced, in the 1930s and through most of World War II.

Junkers Jumo 222

The Jumo 222 was a German high-power multiple-bank in-line piston aircraft engine from Junkers, designed under the management of Ferdinand Brandner of the Junkers Motorenwerke.

Junkers Jumo 204

The Jumo 204 was an opposed-piston, inline, liquid-cooled 6-cylinder aircraft Diesel engine produced by the German manufacturer Junkers. It entered service in 1932. Later engines in the series, the Jumo 205, Jumo 206, Jumo 207 and Jumo 208, differed in stroke, bore, and supercharging arrangements.

BMW 803

The BMW 803 was a German aircraft engine, an attempt by BMW to build a high-output aircraft engine by coupling two BMW 801 engines back-to-back, driving contra-rotating propellers. The result was a 28-cylinder, four-row radial engine, each comprising a multiple-bank in-line engine with two cylinders in each bank, which, due to cooling concerns, were liquid cooled.

Aircraft diesel engine

The aircraft diesel engine or aero diesel is a diesel-powered aircraft engine. They were used in airships and tried in aircraft in the late 1920s and 1930s, but never widely adopted beyond this. Their main advantages are their excellent specific fuel consumption, the reduced flammability and somewhat higher density of their fuel, but these have been outweighed by a combination of inherent disadvantages compared to gasoline-fueled or turboprop engines. The ever-rising cost of avgas and doubts about its future availability have spurred a resurgence in aircraft diesel engine production in the early 2010s.

Continental XI-1430 American aircraft engine

The Continental XI-1430 Hyper engine was a liquid-cooled aircraft engine developed in the United States by a partnership between the US Army Air Corps and Continental Motors. It was the "official" result of the USAAC's hyper engine efforts that started in 1932, but never entered widespread production as it was not better than other available engines when it finally matured. In 1939, the I-1430-3 was designated as the engine to power the Curtiss XP-55, an extremely radical pusher-engine fighter design that would not reach production.

Napier Culverin 1930s British aircraft piston engine

The Napier Culverin was a licensed built version of the Junkers Jumo 204 six-cylinder vertically opposed liquid-cooled diesel aircraft engine built by D. Napier & Son. The name is derived from the French word, culverin, for an early cannon or musket. First flown in 1938, the engine went into limited production, with testing carried out on a Blackburn Iris V biplane flying-boat aircraft and Fairey IIIF biplane.

The Fairey P.16 Prince was a British experimental 1,500 hp 16-cylinder H-type aircraft engine designed and built by Fairey in the late 1930s. The engine did not go into production.

The Michel engine was an unusual form of opposed-piston engine. It was unique in that its cylinders, instead of being open-ended cylinders containing two pistons, were instead joined in a Y-shape and had three pistons working within them.

Potez 6D 1940s French aircraft piston engine

The Potez 6D is a French six cylinder inverted inline aircraft engine put into production after World War II in normal and supercharged versions. Unsupercharged, it produced a take-off power of 179 kW (240 hp) at 2,530 rpm.

The Potez 8D is the largest member of the Potez D series of air-cooled piston aircraft engines which share several common features. It is a supercharged eight cylinder inverted engine with a take-off power of 373 kW (500 hp).

References

Citations

  1. Johnson, E.R., United States Naval Aviation, 1919-1941: Aircraft, Airships and Ships Between the Wars, p.326: "INLINE ENGINEA type of reciprocating piston engine in which an even (4-6-8-12) number of cylinders are arranged either in a straight line or in a V-type configuration directly above (or below) the crankcase. Most early inline aircraft engines were water-cooled via a radiator system, though air-cooled types began to appear during the 1930s."
  2. Bowman, M., Hector, G, P-47 Thunderbolt Vs. Bf 109G/K: Europe 1943-45, p.8
  3. "Napier Lion". The Racing Campbells . Archived from the original on 2009-09-14. Retrieved 2012-06-30. The Lion was a 12-cylinder W-block inline aircraft engine built by Napier & Son starting in 1917, and ending in the 1930s.{{cite web}}: External link in |work= (help)
  4. Johnson, E.R., United States Naval Aviation, 1919-1941: Aircraft, Airships and Ships Between the Wars, p.303: "General specifications: type, single-seat torpedo plane; one 450-hp Napier Lion 1B inline engine; length..."
  5. 1 2 Wilkinson, Stephan (2005). "DB-601". Man And Machine: The Best of Stephan Wilkinson. Globe Pequot. p. 174. ISBN   1-59228-812-X . Retrieved 2013-01-24. The widest part of the enginethe two banks of cylinder headswere down near the already wide midline of the fuselage.
  6. Meyers, W. G. (September 1925). Mitchell, Harley W. (ed.). "Future Possibilities in Aircraft Engine Design". Aeronautics . Chicago, IL USA: Aeronautical Publications. 5 (3): 85. Retrieved 2013-01-24. (4) Its high center of thrust insures better flying qualities by offsetting a tendency of the ship to climb when full power is suddenly thrown on,
  7. SAE Transactions, Volume 20, Part 1. Society of Automotive Engineers. 1926. The Inverted Type Has Four Major Advantages: (a) Improved Visibility, (b) High Center of Thrust, (c) Accessibility for Maintenance, and (d) Gravity Fuel-Feed found to be particularly desirable for load-carrying airplanes...

Bibliography