![Deltic 18 firing order](https://upload.wikimedia.org/wikipedia/commons/d/d0/Deltic_18_firing_order.gif)
The Napier Deltic engine is a British
opposed-piston
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 f ...
valveless
The Valveless was an English automobile manufactured, after lengthy development, from 1908 until 1915 in Huddersfield, Yorkshire. The successor to the Ralph Lucas Valveless, the car marked the entry of the David Brown & Sons group into the m ...
,
supercharged
In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement.
The current categorisation is that a supercharger is a form of forced induct ...
uniflow scavenged,
two-stroke
A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a Thermodynamic power cycle, power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being comple ...
diesel engine
The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-call ...
used in
marine
Marine is an adjective meaning of or pertaining to the sea or ocean.
Marine or marines may refer to:
Ocean
* Maritime (disambiguation)
* Marine art
* Marine biology
* Marine debris
* Marine habitats
* Marine life
* Marine pollution
Military
* ...
and
locomotive
A locomotive or engine is a rail transport vehicle that provides the Power (physics), motive power for a train. If a locomotive is capable of carrying a payload, it is usually rather referred to as a multiple unit, Motor coach (rail), motor ...
applications, designed and produced by
D. Napier & Son. Unusually, the
cylinder
A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base.
A cylinder may also be defined as an infin ...
s were disposed in a three-bank triangle, with a
crankshaft
A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting ...
at each corner of the triangle.
The term Deltic (meaning "in the form of the Greek letter (capital)
delta
Delta commonly refers to:
* Delta (letter) (Δ or δ), a letter of the Greek alphabet
* River delta, at a river mouth
* D (NATO phonetic alphabet: "Delta")
* Delta Air Lines, US
* Delta variant of SARS-CoV-2 that causes COVID-19
Delta may also re ...
") is used to refer to both the Deltic E.130 opposed-piston, high-speed diesel engine and the locomotives produced by
English Electric
N.º UIC: 9094 110 1449-3 (Takargo Rail)
The English Electric Company Limited (EE) was a British industrial manufacturer formed after the Armistice of 11 November 1918, armistice of World War I by amalgamating five businesses which, during th ...
using these engines, including its
demonstrator locomotive named ''DELTIC'' and the production version for
British Railways
British Railways (BR), which from 1965 traded as British Rail, was a state-owned company that operated most of the overground rail transport in Great Britain from 1948 to 1997. It was formed from the nationalisation of the Big Four British rai ...
, which designated these as (
TOPS
Total Operations Processing System (TOPS) is a computer system for managing railway locomotives and rolling stock, known for many years of use in the United Kingdom.
TOPS was originally developed between the Southern Pacific Railroad (SP), S ...
)
Class 55.
A single, half-sized, turbocharged Deltic power unit also featured in the English Electric-built Type 2 locomotive, designated as the
Class 23. Both locomotive and engine became better known as the "Baby Deltic".
History and design
The Deltic story began in 1943 when the British
Admiralty
Admiralty most often refers to:
*Admiralty, Hong Kong
* Admiralty (United Kingdom), military department in command of the Royal Navy from 1707 to 1964
*The rank of admiral
* Admiralty law
Admiralty can also refer to:
Buildings
*Admiralty, Tr ...
set up a committee to develop a high-power, lightweight diesel engine for
motor torpedo boats.
Hitherto in the
Royal Navy
The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...
, such boats had been driven by
petrol engine
A petrol engine (gasoline engine in American English) is an internal combustion engine designed to run on petrol (gasoline). Petrol engines can often be adapted to also run on fuels such as liquefied petroleum gas and ethanol blends (such as ''E ...
s, but their highly flammable fuel made them vulnerable to fire, unlike diesel-powered
E-boat
E-boat was the Western Allies' designation for the fast attack craft (German: ''Schnellboot'', or ''S-Boot'', meaning "fast boat") of the Kriegsmarine during World War II; ''E-boat'' could refer to a patrol craft from an armed motorboat to a lar ...
s. A patent for an engine, similar in complexity, but with four lines of pistons, not just three, was filed in 1930 by
Wifredo Ricart
Wifredo Pelayo Ricart Medina (15 May 1897 – 19 August 1974) was a Spanish engineer, designer and executive manager in the automotive industry, who spent his professional career in Spain and Italy.
The Barcelona "Happy Twenties"
Born in Bar ...
, linked to
Alfa-Romeo
Alfa Romeo Automobiles S.p.A. () is an Italian luxury car manufacturer and a subsidiary of Stellantis. The company was founded on 24 June 1910, in Milan, Italy. "Alfa" is an acronym of its founding name, "Anonima Lombarda Fabbrica Automobili." "A ...
, and to the Spanish INI truck maker
Pegaso
Pegaso (, "Pegasus") was a Spanish manufacturer of trucks, buses, tractors, armored vehicles, and, for a while, to train apprentices, and have a good brand image, some sports cars. The parent company, Enasa, was created in 1946 and based in the ...
Pat ES0118013.
Until this time, diesel engines had poor
power-to-weight ratio
Power-to-weight ratio (PWR, also called specific power, or power-to-mass ratio) is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measuremen ...
s and low speed. Before the war, Napier had been working on an aviation diesel design known as the
Culverin
A culverin was initially an ancestor of the hand-held arquebus, but later was used to describe a type of medieval and Renaissance cannon. The term is derived from the French "''couleuvrine''" (from ''couleuvre'' "grass snake", following the La ...
after licensing versions of the
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, diffe ...
. The Culverin was an opposed-piston, two-stroke design. Instead of each cylinder having a single piston and being closed at one end with a
cylinder head
In an internal combustion engine, the cylinder head (often abbreviated to simply "head") sits above the cylinders and forms the roof of the combustion chamber.
In sidevalve engines, the head is a simple sheet of metal; whereas in more modern ov ...
, the Jumo-based design used an elongated cylinder containing two pistons moving in opposite directions towards the centre. This obviates the need for a heavy
cylinder head
In an internal combustion engine, the cylinder head (often abbreviated to simply "head") sits above the cylinders and forms the roof of the combustion chamber.
In sidevalve engines, the head is a simple sheet of metal; whereas in more modern ov ...
, as the opposing piston filled this role. On the downside, the layout required separate crankshafts on each end of the engine that must be coupled through gearing or shafts. The primary advantages of the design were
uniflow breathing and a rather "flat" engine.
The Admiralty required a much more powerful engine, and knew about Junkers' designs for multicrankshaft engines of straight-six and diamond forms. The Admiralty felt that these would be a reasonable starting point for the larger design that it required. The result was a triangle, the cylinder banks forming the sides, with
crankshaft
A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting ...
s at each corner connected by phasing gears to a single output shaft—effectively three separate V-12 engines. The Deltic could be produced with varying numbers of cylinders; 9 and 18 were the most common, having either three or six banks of cylinders, respectively. In 1946, the Admiralty placed a contract with the English Electric Company, parent of Napier, to develop this engine.
One feature of the engine was the way that 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 blowers to improve cylinder exhaust
scavenging
Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding be ...
. The inlet/outlet port order is In/Out/In/Out/In/Out going around the triangular ring (i.e. the inlet and outlet manifold arrangements have
C3 rotational symmetry
Rotational symmetry, also known as radial symmetry in geometry, is the property a shape has when it looks the same after some rotation by a partial turn. An object's degree of rotational symmetry is the number of distinct orientations in which i ...
).
Earlier attempts at designing such an engine met with the difficulty of arranging the pistons to move in the correct manner, for all three cylinders in one delta, and this was the problem that caused
Junkers Motorenbau to leave behind work on the delta-form while continuing to prototype a diamond-form, four-crankshaft, 24-cylinder
Junkers Jumo 223
The Junkers Jumo 223 was an experimental 24-cylinder aircraft engine based on the Junkers Jumo 205. Like the Jumo 205, it was an opposed piston two-stroke diesel engine. It had four banks of six cylinders in a rhomboid configuration, with four cr ...
. Mr. Herbert Penwarden, a senior draughtsman with the Admiralty Engineering Laboratory, suggested that one crankshaft needed to revolve anticlockwise to achieve the correct piston-phasing, so Napier designers produced the necessary gearing so one of them rotated in the opposite direction to the other two.
Being 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 "fork and blade" connecting rods, the latter an "inlet" piston used to open and close the inlet port, and the former an "exhaust" piston in the adjacent cylinder to open and close the exhaust port. This would have led the firing in each bank of cylinders to be 60° apart, but arranging that each cylinder's exhaust piston would lead its inlet piston by 20° of crankshaft rotation was adopted. 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 Volumetric efficiency (VE) in internal combustion engine engineering is defined as the ratio of the mass density of the air-fuel mixture drawn into the cylinder at atmospheric pressure (during the intake stroke) to the mass density of the same volu ...
for the fresh air charge. This required the firing events for adjacent cylinders to be 40° apart. For the 18-cylinder design, firing events could be interlaced over all six banks. This led to the even, buzzing exhaust note of the Deltic, with a charge ignition every 20° of crankshaft revolution, and a lack of
torsional vibration
Torsional vibration is angular vibration of an object—commonly a shaft along its axis of rotation. Torsional vibration is often a concern in power transmission systems using rotating shafts or couplings where it can cause failures if not contr ...
, ideal for use in mine-hunting vessels. The 9-cylinder design, having three banks of cylinders, has its crankshafts rotating in the opposite direction. The exhaust lead of 20° is added to the 60° between banks, giving firing events for adjacent cylinders in the same bank 80° apart. Interlacing firing events over all three banks of cylinders still leads to an even buzzing exhaust note, and charge ignition occurring every 40° of crankshaft revolution with consequent reduction of torsional vibration.
Although the engine was cylinder-ported and required no
poppet valve
A poppet valve (also called mushroom valve) is a valve typically used to control the timing and quantity of gas or vapor flow into an engine.
It consists of a hole or open-ended chamber, usually round or oval in cross-section, and a plug, usual ...
s, each bank had a
camshaft
A camshaft is a shaft that contains a row of pointed cams, in order to convert rotational motion to reciprocating motion. Camshafts are used in piston engines (to operate the intake and exhaust valves), mechanically controlled ignition systems ...
, driven at crankshaft speed. This was used solely to drive the fuel-injection pumps, each cylinder having its own injector and pump, driven by its own cam lobe.
Uses
Naval service
![HMS Ledbury (M30) - Portsmouth 2007 - BB](https://upload.wikimedia.org/wikipedia/commons/b/b8/HMS_Ledbury_%28M30%29_-_Portsmouth_2007_-_BB.jpg)
Development began in 1947 and the first Deltic model was the D18-11B, produced in 1950. It was designed to produce at 2000
rpm
Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines.
Standards
ISO 80000-3:2019 defines a unit of rotation as the dimensionl ...
for a 15-minute rating; the continuous rating being at 1700 rpm, based on a 1000-hour overhaul or replacement life. By January 1952 six engines were available, enough for full development and endurance trials. A captured German
E-Boat
E-boat was the Western Allies' designation for the fast attack craft (German: ''Schnellboot'', or ''S-Boot'', meaning "fast boat") of the Kriegsmarine during World War II; ''E-boat'' could refer to a patrol craft from an armed motorboat to a lar ...
S212 was selected as it was powered by Mercedes-Benz diesels with approximately the same power as the 18-
cylinder
A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base.
A cylinder may also be defined as an infin ...
Deltics. When two of the three
Mercedes-Benz
Mercedes-Benz (), commonly referred to as Mercedes and sometimes as Benz, is a German luxury and commercial vehicle automotive brand established in 1926. Mercedes-Benz AG (a Mercedes-Benz Group subsidiary established in 2019) is headquartere ...
engines were replaced, the compactness of the Napier engines was graphically illustrated—they were half the size of the original engines and approximately one fifth the weight.
Proving successful, Deltic Diesel engines became a common power plant in small and fast naval craft. The
Royal Navy
The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...
used them first in the fast attack craft.
Subsequently they were used in a number of other smaller attack craft. Being largely of aluminium construction, their low magnetic signature allowed their use in
mine countermeasures vessel
A mine countermeasures vessel or MCMV is a type of naval ship designed for the location of and destruction of naval mines which combines the role of a minesweeper and minehunter
A minehunter is a naval vessel that seeks, detects, and destro ...
s and the Deltic was selected to power the s. The Deltic engine is still in service in the . These versions are de-rated to reduce engine stress.
Deltic Diesels served in MTBs and
PT boat
A PT boat (short for patrol torpedo boat) was a motor torpedo boat used by the United States Navy in World War II. It was small, fast, and inexpensive to build, valued for its maneuverability and speed but hampered at the beginning of the wa ...
s built for other navies. Particularly notable was the
Norwegian
Norwegian, Norwayan, or Norsk may refer to:
*Something of, from, or related to Norway, a country in northwestern Europe
*Norwegians, both a nation and an ethnic group native to Norway
*Demographics of Norway
*The Norwegian language, including the ...
''Tjeld'' or ''Nasty'' class, which was also sold to Germany, Greece, and the
United States Navy
The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...
. ''Nasty''-class boats served in the
Vietnam War
The Vietnam War (also known by #Names, other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vie ...
, largely for covert operations.
Smaller nine-cylinder ''Deltic 9'' engines were used as marine engines, notably by minesweepers. The Ton-class vessels were powered by a pair of Deltic 18s and used an additional Deltic 9 for power generation for their
magnetic influence
Magnetic pistol is the term for the device on a torpedo or naval mine that detects its target by its magnetic field, and triggers the fuse for detonation. A device to detonate a torpedo or mine on ''contact'' with a ship or submarine is known as a ...
sweep.
[ Vessey, Napier Powered, p. 102] The Hunt class used three Deltic 9s, two for propulsion and again one for power generation, but this time with a hydraulic pump integrated to power bow-thrusters for slow-speed manœuvring,
[ Vessey, Napier Powered, p. 104] until a refurbishment programme by
BAE Systems
BAE Systems plc (BAE) is a British multinational arms, security, and aerospace company based in London, England. It is the largest defence contractor in Europe, and ranked the seventh-largest in the world based on applicable 2021 revenues. ...
, that ran from 2010 to 2018, replaced the Deltic with
Caterpillar CAT C32 engines in the eight remaining commissioned Royal Navy vessels.
Railway use
![Napier Deltic Engine](https://upload.wikimedia.org/wikipedia/commons/2/2a/Napier_Deltic_Engine.jpg)
The "Deltic" engines were used in two types of British rail locomotive: the 1961–62 built class 55 and the 1959 built class 23. These locomotive types were known as "Deltics" and "Baby Deltics", respectively.
The Class 55 used two D18-25 series II type V Deltic engines: mechanically blown 18-cylinder engines each rated at continuous at 1500 rpm. The Class 23 used a single less powerful nine-cylinder
turbocharged
In an internal combustion engine, a turbocharger (often called a turbo) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake gas, forcing more air into the engine in order to pro ...
T9-29 Deltic of .
[ Vessey, Napier Powered, p. 110][ Webb, Deltic Engines, p. 50]
Six out of the original 22 "Deltic" locomotives survive, four of which have, at various times since 1996, returned to work on the main line, operating both service trains and charter trains. D9000 "Royal Scots Grey", the doyen of the class, was returned to main line serviceable status in 1996 and continued to work throughout the UK for nearly twenty years. Following a power unit failure this locomotive was fitted, for a time, with an ex-Norwegian Navy T18-37K type, after various modifications were cleverly designed to make the new unit compatible.
Fire department use
The New York City Fire Department used a Napier Deltic engine to power their one-of-a-kind "Super Pumper System". This was a very-high-volume trailer-mounted fire pump with a separate tender.
Reliability in service
While the Deltic engine was successful in marine and rail use and very powerful for its size and weight, it was a highly strung unit, requiring careful maintenance. This led to a policy of unit replacement rather than repair in situ. Deltic engines were easily removed after breakdown, generally being sent back to the manufacturer for repair, although after initial contracts expired both the Royal Navy and British Railways set up their own workshops for overhauls.
Turbo-compound Deltic
The "E.185" or "Compound Deltic"
turbo-compound
A turbo-compound engine is a reciprocating engine that employs a turbine to recover energy from the exhaust gases. Instead of using that energy to drive a turbocharger as found in many high-power aircraft engines, the energy is instead sent to ...
variant was planned
and a single prototype was built in 1956
[ Boyle, The Napier Way, p. 121] and tested in 1957.
[ Vessey, Napier Powered, pp. 107–108] This capitalised on Napier's experience with both the "
Nomad
A nomad is a member of a community without fixed habitation who regularly moves to and from the same areas. Such groups include hunter-gatherers, pastoral nomads (owning livestock), tinkers and trader nomads. In the twentieth century, the popu ...
" and its increasing involvement with
gas turbine
A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the directi ...
s. It used the Deltic as the
gas generator
A gas generator is a device for generating gas. A gas generator may create gas by a chemical reaction or from a solid or liquid source, when storing a pressurized gas is undesirable or impractical.
The term often refers to a device that uses a ...
inside a gas turbine, with both a twelve-stage
axial compressor
An axial compressor is a gas compressor that can continuously pressurize gases. It is a rotating, airfoil-based compressor in which the gas or working fluid principally flows parallel to the axis of rotation, or axially. This differs from other ...
and a three-stage gas turbine. Unlike the Nomad, this turbine was not mechanically coupled to the crankshaft, but merely drove the compressor. It was hoped that it would produce 6,000 horsepower, with fuel economy and
power-to-weight ratio
Power-to-weight ratio (PWR, also called specific power, or power-to-mass ratio) is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measuremen ...
"second to none".
[ Boyle, The Napier Way, p. 221] Predictions by the engineers closely connected with it were that
connecting rod
A connecting rod, also called a 'con rod', is the part of a piston engine which connects the piston to the crankshaft. Together with the crank, the connecting rod converts the reciprocating motion of the piston into the rotation of the cranksh ...
failure would be the limit on this power, failing at around 5,300 bhp. On test it actually produced 5,600 bhp before throwing a connecting rod through the crankcase just as predicted.
Naval interest had waned by 1958 in favour of the pure gas turbine, despite its heavier fuel consumption, and no further development was carried out.
Comparable engines
*
Junkers Jumo 223
The Junkers Jumo 223 was an experimental 24-cylinder aircraft engine based on the Junkers Jumo 205. Like the Jumo 205, it was an opposed piston two-stroke diesel engine. It had four banks of six cylinders in a rhomboid configuration, with four cr ...
*
Zvezda M503
The Zvezda M503 (built at AO Zvezda at St Petersburg) is a maritime 7 bank, 42 cylinder diesel radial engine built in the 1970s by the Soviet Union. Its primary use was in Soviet missile boats that used three of these engines.
This engine may h ...
*
Achates Power
Achates Power is an American developer of opposed-piston engine, opposed-piston, two-stroke engine, two-stroke, compression ignition engines for use in commercial and passenger vehicles. Based in San Diego, California, the company was founded in 2 ...
*
Fairbanks Morse 38 8-1/8 diesel engine
The Fairbanks-Morse 38 8-1/8 is a diesel engine of the two-stroke, opposed-piston type. It was developed in the 1930s, and is similar in arrangement to a contemporary series of German Bombers aircraft diesels. The engine was used extensively in US ...
See also
*
Deltic Preservation Society
The Deltic Preservation Society is a railway preservation group based in England. The society is dedicated to the preservation and restoration of the remaining Class 55 "Deltic" diesel locomotives operated by British Rail from the 1960s to the ...
References
Further reading
*
*
*
*
*
*
External links
Deltic technical detailsThe Deltic Preservation SocietyHunt Class– Deltic-powered Mine Countermeasure Vessel
– 3-D animations of the piston motion in the Deltic engine
* – rebuilding of one of D9016 ''Gordon Highlanders engines after an exhaust silencer fire in 1999
{{Piston engine configurations
Napier engines
Piston engine configurations
Piston ported engines
Diesel locomotive engines
Marine diesel engines
Two-stroke diesel engines
Opposed piston engines
Diesel engines by model
Deltic