Delta engine

Information about Delta engine

Napier Deltic powered British Rail Class 55 Alycidon, at the National Railway Museum, York, UK

The term Deltic (meaning in the form of the Greek letter Delta) is used to refer to both the opposed-piston high-speed diesel engine designed and produced by D Napier & Son, and the locomotives produced by English Electric using these engines, including their demonstrator locomotive named DELTIC and the production version for British Railways, who designated these as Class 55.

History

An animated schematic of a Deltic engine. The inlet is coloured green and the outlet purple. Notice the bottom shaft contra-rotating with respect to the other two; the lag between the exhaust and inlet ports opening; and that ignition occurs when the pistons are not at equal positions in the cylinder. (NB The left-hand cylinder is shown wrongly: its ports and timing should be reversed.)

The Deltic story began in 1943 when the British Admiralty set up a committee to develop a high-power, lightweight diesel engine for Motor Torpedo Boat^[1]. Hitherto in the Royal Navy, such boats had been driven by petrol engines but this fuel is highly flammable, making them vulnerable to fire, and at a disadvantage compared to the German diesel-powered E-boats.

Until this time, diesel engines had poor power-to-weight ratio and low speed. Before the war, Napier had been working on aviation diesel designs (licensed versions of the Junkers Jumo 204) and the Admiralty felt these would be a reasonable starting point for the larger design they required.

The original Napier Culverin was an opposed piston design. Instead of each cylinder having a single piston and being closed at one end with a cylinder head, the elongated cylinder contained two pistons moving in opposite directions towards the centre. This negates the need for a heavy cylinder head. This led to a rather "flat" engine, intended to be buried in the wings of large aircraft. The Admiralty required a much more powerful engine, so for the added power Napier took three of their original Culverins and "bolted them together".

The result was an inverted triangle, the cylinder banks forming the sides, and tipped by three crankshafts, one at each corner. The crankshafts were connected with phasing gears to drive one output shaft. Various models of Deltic engine could be produced with varying numbers of cylinders, though nine and eighteen cylinders were the most common, having three and six cylinders per bank respectively. In 1946, the Admiralty placed a contract with the English Electric Company, parent of Napier, to develop this engine^[1].

One of the interesting features of this engine was the clever way the crankshaft phasing was arranged to allow for exhaust port lead and inlet port lag. These engines are called 'uniflow' designs because the flow of gas into and out of the cylinder is one way, assisted by mild supercharging to improve cylinder exhaust scavenging.

Napier Deltic engine at the National Railway Museum, York, UK

Earlier attempts at designing such an engine failed because of the difficulty in arranging the pistons to move in the correct manner, for all three cylinders in one delta. Napier solved this problem by gearing the crankshafts so that one of them rotated in the opposite direction to the other two.

In an opposed piston design with no inlet or exhaust valves, and no ability to vary the port positions, the Deltic design arranged each crankshaft to connect two adjacent pistons operating in different cylinders in the same plane, using forked connecting rods, one an 'inlet' piston used to open and close the inlet port, and the other an 'exhaust' piston in the adjacent cylinder to open and close the exhaust port.

Crankshaft connecting-rod journals were arranged so that each cylinder's exhaust piston 'led' its inlet piston by 20 degrees of crankshaft rotation. This allowed the exhaust port to be opened well before the inlet port, and allowed the inlet port to be closed after the exhaust port, which led to both good scavenging of exhaust gas, and good volumetric efficiency for the fresh air charge. It suffered from the disadvantage that the two pistons contributed unequally to power output.

Development began in 1947 and the first Deltic unit was produced in 1950. By January 1952 six engines were available, enough for full development and endurance trials. An ex-German E-Boat, powered by three Mercedes-Benz diesel engines, was selected for these trials, since its power units were of approximately equal power to the new 18 cylinder Deltic engines. Two of the three Mercedes-Benz engines were replaced with Napier Deltics, the compactness of the Deltic being graphically illustrated: they were half the size of the original engines. The Deltic weighed one fifth of its contemporaries of equivalent power^[1].

Proving successful, Deltic diesel engines became a common powerplant in small, fast, naval craft. The Royal Navy used them first in the Dark-class fast attack craft. Subsequently they were used in a number of other smaller attack craft. The low magnetic signature lent itself to use in mine countermeasure vessels and the Deltic was selected to power the Ton-class minesweeper. The Deltic engine is still in service in the Hunt-class. These versions are de-rated to lower the stress on the engine.

The Deltic-powered Hunt class Mine Countermeasure Vessel HMS Ledbury

Deltic diesels served in MTBs and PT Boats built for other navies. Particularly notable Was the Norwegian Tjeld or Nasty class, which were also sold to Germany, Greece, and the United States Navy. Nasty-class boats served in the Vietnam War, largely for covert operations.

While the Deltic engine was successful and very powerful for its size and weight, it was a high-strung unit, requiring much maintenance. This led to a policy of maintenance by unit replacement rather than repair in place. Deltic engines were easily removed upon breakdown, generally being sent back to the manufacturer for repair.

A turbo-compound variant of the Deltic was planned^[1]. This would have inserted the turbine stage from a Rolls-Royce Nene turbojet into the centre of the delta. The engine acted as the gas generator, driving the turbine with the exhaust gases, recycling some energy that would otherwise have been lost. Such an engine was hoped to produce 6,000 horse power.

References

1. ^ Rebuilding the Royal Navy. Warship design since 1945, D. K. Brown & George Moore, Chatham Publishing, 2003, ISBN 1-8617-6222-4

External links

Deltic technical details.
The Deltic Preservation Society.
Hunt Class deltic powered Mine Countermeasure Vessel.
Deltic Animations 3-D animations of the piston motion in the Deltic engine.

Delta (uppercase Δ, lowercase δ) is the fourth letter of the Greek alphabet. In the system of Greek numerals it has a value of 4. It was derived from the Phoenician letter Dalet .
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Napier & Son was a British engine manufacturer and one of the most important aircraft engine manufacturers in the early to mid 20th Century. Their post-World War I Lion was the most powerful engine in the world for some time in the 1920s and into the 1930s, and their Sabre produced
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English Electric was a 20th-century British industrial manufacturer, initially of electric motors, and expanding to include railway locomotives and aviation, before becoming part of GEC.

History

1917: Dick, Kerr & Co.

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DP1, or Prototype Deltic is a demonstrator locomotive built by English Electric in 1955. This locomotive resulted in twenty-two similar locomotives being ordered by British Rail, which became their Class 55.
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British Railways (BR), which later traded as British Rail, ran most of the British railway system from the nationalisation of the 'Big Four' British railway companies in 1948 until privatisation in stages from 1994 to 1997.
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Class 55 is a class of diesel locomotive built in between 1961 and 1962 by English Electric. They were designed for the high-speed express passenger services on the East Coast Main Line between London King's Cross and Edinburgh.
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This article or section needs copy editing for grammar, style, cohesion, tone and/or spelling.
You can assist by [ editing it] now. A how-to guide is available, as is general .
This article has been tagged since September 2007.
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Motor Torpedo Boat (MTB) was the name given to fast torpedo boats by the United States Navy, the Royal Norwegian Navy, the Royal Canadian Navy and the Royal Navy.

During World War II the US Navy boats were usually called by their hull classification symbol of "PT" (from
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Naval Service

Components
Royal Navy

Surface Fleet
Fleet Air Arm
Submarine Service
Royal Navy Regulating Branch
Royal Naval Reserve
Queen Alexandra's Royal Naval Nursing Service

Royal Marines

(includes Royal Marines Reserve)

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A Petrol engine or Gasoline engine is an internal combustion engine with spark-ignition designed to run on petrol (gasoline) and similar volatile fuels. It differs from a diesel engine in the method of mixing the fuel and air, and in the fact that it uses spark plugs.
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Anthem
"Das Lied der Deutschen" (third stanza)
also called "Einigkeit und Recht und Freiheit"
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Schnellboot or S-boot ("fast craft") was a German small, fast torpedo boat, which saw service during World War II. The S-boote were approximately twice as large as its American and British counterparts.
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Power-to-weight ratio (specific power) is a calculation commonly applied to engines and other mobile power plants to enable the comparison of one unit (design) to another. Power-to-weight ratio is a measurement of actual performance of any engine (power plant).
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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 Jumo 204 first entered service in 1932.
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opposed piston engine is one in which the cylinders are double-ended, with a piston at each end and no cylinder head. Some variations of the Opposed Piston or OP designs can use a single crankshaft like the Doxford ship engines [1] and the Commer OP truck engines
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cylinder head sits atop the cylinders and consists of a platform containing part of the combustion chamber and the location of the valves and spark plugs. In a flathead engine, the mechanical parts of the valve train are all contained within the block, and the head is essentially a
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crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation. It typically connects to a flywheel, to reduce the pulsation characteristic of the four-stroke cycle, and sometimes a torsional
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English Electric was a 20th-century British industrial manufacturer, initially of electric motors, and expanding to include railway locomotives and aviation, before becoming part of GEC.

History

1917: Dick, Kerr & Co.

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Naval Service

Components
Royal Navy

Surface Fleet
Fleet Air Arm
Submarine Service
Royal Navy Regulating Branch
Royal Naval Reserve
Queen Alexandra's Royal Naval Nursing Service

Royal Marines

(includes Royal Marines Reserve)

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A mine countermeasures vessel or MCMV is a type of naval ship tasked with the location of and destruction of naval mines. It combines the role of a minesweeper and minehunter in one hull. The term MCMV is also applied collectively to minehunters or minesweepers.
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The Ton class were coastal minesweepers built for the Royal Navy and South African Navy in the 1950s. They were intended to meet the threat of seabed mines laid in shallow coastal waters, rivers, ports and harbours, a task for which the existing ocean-going minesweepers of the
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Hunt class is a class of thirteen mine countermeasure vessels (MCMV) of the Royal Navy. They combine the separate role of the traditional minesweeper and that of the active minehunter in one hull. They have a secondary role as fisheries patrol vessels.
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PT boat was a motor torpedo boat (hull classification symbol "PT", for "Patrol Torpedo"), a small, fast vessel used by the United States Navy in World War II to attack larger surface ships. The PT boat squadrons were nicknamed "the mosquito fleet".
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Motto

Royal: Alt for Norge ("Everything for Norway")
1814 Eidsvoll oath: Enige og tro til Dovre faller
("United and faithful until the mountains of Dovre crumble")

Anthem
Ja, vi elsker

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The Tjeld class were a class of fast patrol boats (FPB) designed in Norway. They were used as torpedo boats in Norway where this type of vessel were called MTBs or motor torpedo boats (motortorpedobÃ¥t). The class were also known as the Nasty class.
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United States Navy (USN) is the branch of the United States armed forces responsible for conducting naval operations. The U.S. Navy currently has over 340,000 personnel on active duty and nearly 128,000 in the Navy Reserve.
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Total dead: ~314,000
Total wounded: ~1,490,000 North Vietnam and NLF
dead and missing: ~1,100,000 [1] [2] [3] [4]
wounded: ~600,000+ [5]
People's Republic of China
dead: 1,446
wounded: 4,200

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Turbo-compound engine is a compound engine that uses a blowdown turbine to recover energy from the exhaust gases of a piston engine. The turbine is usually connected to the crankshaft mechanically but also electric and hydraulic systems have been investigated.
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Search Dictionary

(May not be accurate.)

Piston engine configurations • • [ e]
Straight	Single, 2, 3, 4, 5, 6, 8, 9, 10, 12, 14
Flat	2, 4, 6, 8, 10, 12, 16
V	2, 4, 5, 6, 8, 10, 12, 16, 20, 24
W	8, 12, 16, 18
Other inline	H, U, Square, VR, Opposed, X
Other	Radial, Rotary, Pistonless (Wankel)

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Delta engine

Information about Delta engine

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