A turboshaft engine is a form of

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 ...

that is optimized to produce shaftpower rather than jet thrust. In concept, turboshaft engines are very similar to

turbojet The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and ...

s, with additional turbine expansion to extract heat energy from the exhaust and convert it into output shaft power. They are even more similar to

turboprop A turboprop is a turbine engine that drives an aircraft propeller. A turboprop consists of an intake, reduction gearbox, compressor, combustor, turbine, and a propelling nozzle. Air enters the intake and is compressed by the compressor. Fuel ...

s, with only minor differences, and a single engine is often sold in both forms. Turboshaft engines are commonly used in applications that require a sustained high power output, high reliability, small size, and light weight. These include

helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...

auxiliary power unit An auxiliary power unit (APU) is a device on a vehicle that provides energy for functions other than propulsion. They are commonly found on large aircraft and naval ships as well as some large land vehicles. Aircraft APUs generally produce 115& ...

boat A boat is a watercraft of a large range of types and sizes, but generally smaller than a ship, which is distinguished by its larger size, shape, cargo or passenger capacity, or its ability to carry boats. Small boats are typically found on inl ...

s and

ship A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research, and fishing. Ships are generally distinguished ...

tank A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and good battlefield mobility provided by tracks and a powerful engin ...

hovercraft A hovercraft, also known as an air-cushion vehicle or ACV, is an amphibious Craft (vehicle), craft capable of travelling over land, water, mud, ice, and other surfaces. Hovercraft use blowers to produce a large volume of air below the hull ...

, and stationary equipment.

Overview

A turboshaft engine may be made up of two major parts assemblies: the 'gas generator' and the 'power section'. The gas generator consists of the

compressor A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor. Compressors are similar to pumps: both increase the pressure on a fluid and both can transp ...

combustion chamber A combustion chamber is part of an internal combustion engine in which the fuel/air mix is burned. For steam engines, the term has also been used for an extension of the firebox which is used to allow a more complete combustion process. Interna ...

s with ignitors and fuel

nozzle A nozzle is a device designed to control the direction or characteristics of a fluid flow (specially to increase velocity) as it exits (or enters) an enclosed chamber or pipe. A nozzle is often a pipe or tube of varying cross sectional area, a ...

s, and one or more stages of

turbine A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced by a turbine can be used for generating e ...

. The power section consists of additional stages of turbines, a

gear reduction Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differ ...

system, and the shaft output. The gas generator creates the hot expanding gases to drive the power section. Depending on the design, the engine accessories may be driven either by the gas generator or by the power section. In most designs, the gas generator and power section are mechanically separate so they can each rotate at different speeds appropriate for the conditions, referred to as a ' free power turbine'. A free power turbine can be an extremely useful design feature for vehicles, as it allows the design to forgo the weight and cost of complex multiple-ratio transmissions and

clutch A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). ...

es. An unusual example of the turboshaft principle is the

Pratt & Whitney F135 The Pratt & Whitney F135 is an afterburning turbofan developed for the Lockheed Martin F-35 Lightning II, a single-engine strike fighter. It has two variants; a Conventional Take-Off and Landing ( CTOL) variant used in the F-35A and F-35C, and a ...

-PW-600

turbofan The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft engine, aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the ''turbo'' portion refers to a gas turbine engine which ac ...

engine for the

STOVL A short take-off and vertical landing aircraft (STOVL aircraft) is a fixed-wing aircraft that is able to take off from a short runway (or take off vertically if it does not have a heavy payload) and land vertically (i.e. with no runway). The ...

F-35B The Lockheed Martin F-35 Lightning II is an American family of single-seat, single-engine, all-weather stealth multirole combat aircraft that is intended to perform both air superiority and strike missions. It is also able to provide elect ...

– in conventional mode it operates as a turbofan, but when powering the

LiftFan The Rolls-Royce LiftSystem, together with the F135 engine, is an aircraft propulsion system designed for use in the STOVL variant of the F-35 Lightning II. The complete system, known as the Integrated Lift Fan Propulsion System (ILFPS), was a ...

, it switches partially to turboshaft mode to send 29,000

horsepower Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are the ...

forward through a shaft and partially to turbofan mode to continue to send thrust to the main engine's fan and rear nozzle. Large helicopters use two or three turboshaft engines. The

Mil Mi-26 The Mil Mi-26 (russian: link=no, Миль Ми-26, NATO reporting name: Halo) is a Soviet/Russian heavy transport helicopter. Its product code is ''Izdeliye 90''. Operated by both military and civilian operators, it is the largest and most po ...

uses two Lotarev D-136 at 11,400 hp each, while the

Sikorsky CH-53E Super Stallion The Sikorsky CH-53E Super Stallion is a heavy-lift helicopter operated by the United States military. As the Sikorsky S-80, it was developed from the CH-53 Sea Stallion, mainly by adding a third engine, adding a seventh blade to the main rotor, ...

uses three

General Electric T64 The General Electric T64 is a free-turbine turboshaft engine that was originally developed for use on helicopters, but which was later used on fixed-wing aircraft as well. General Electric introduced the engine in 1964. The original engine desig ...

at 4,380 hp each.

History

The first gas turbine engine considered for an armoured fighting vehicle, the

GT 101 The BMW GT 101 was a turboshaft-type gas turbine engine developed from the BMW 003 aviation engine, that was considered for installation in Nazi Germany's Panther tank. The German Army's development division, the ''Heereswaffenamt'' (Army Ordnan ...

which was based on the

BMW 003 The BMW 003 (full RLM designation 109-003) is an early axial turbojet engine produced by BMW AG in Germany during World War II. The 003 and the Junkers Jumo 004 were the only German turbojet engines to reach production during World War II. W ...

turbojet, was tested in the

Panther tank The Panther tank, officially ''Panzerkampfwagen V Panther'' (abbreviated PzKpfw V) with ordnance inventory designation: ''Sd.Kfz.'' 171, is a German medium tank of World War II. It was used on the Eastern and Western Fronts from mid-1943 to ...

in mid-1944. The first turboshaft engine for

rotorcraft A rotorcraft or rotary-wing aircraft is a heavier-than-air aircraft with rotary wings or rotor blades, which generate lift by rotating around a vertical mast. Several rotor blades mounted on a single mast are referred to as a rotor. The Internati ...

was built by the French engine firm

Turbomeca Safran Helicopter Engines, previously known as Turbomeca, is a French manufacturer of low- and medium-power gas turbine turboshaft engines for helicopters. The company also produces gas turbine engines for aircraft and missiles, as well as turbin ...

, led by its founder

Joseph Szydlowski Joseph Szydlowski (originally Józef Szydłowski; November 21, 1896, Skryhiczyn (in Chełm County, Poland), – July 16, 1988 in Israel), was a Polish- Israeli aircraft engine designer who founded Turbomeca in France. Biography and career A ...

. In 1948, they built the first French-designed turbine engine, the 100-shp 782. Originally conceived as an

, it was soon adapted to aircraft propulsion, and found a niche as a powerplant for turboshaft-driven helicopters in the 1950s. In 1950, Turbomeca used its work from the 782 to develop the larger 280-shp Artouste, which was widely used on the

Aérospatiale Alouette II The Aérospatiale Alouette II (, " lark"; company designations SE 313 and SA 318) is a French light helicopter originally manufactured by Sud Aviation and later Aérospatiale. It was the first production helicopter powered by a gas turbine ...

and other helicopters. This was following the experimental installation of a

Boeing T50 The Boeing T50 (company designation Model 502) was a small turboshaft engine produced by Boeing. Based on Boeing's earlier Model 500 gas generator, the T50's main application was in the QH-50 DASH helicopter drone of the 1950s. An up-rated versi ...

turboshaft in an example of the

Kaman K-225 The Kaman K-225 is an American experimental helicopter developed by Kaman Aircraft. One example was modified to become the world's first gas turbine-powered helicopter. Design and development The K-125 was Charles Kaman's first helicopter, whi ...

synchropter on December 11, 1951, as the world's first-ever turboshaft-powered helicopter of any type to fly. The

T-80 The T-80 is a main battle tank (MBT) that was designed and manufactured in the former Soviet Union and manufactured in Russia. The T-80 is based on the T-64, while incorporating features from the later T-72. The chief designer of the T-80 was So ...

tank, which entered service with the

Soviet Army uk, Радянська армія , image = File:Communist star with golden border and red rims.svg , alt = , caption = Emblem of the Soviet Army , start_date ...

in 1976, was the first tank to use a gas turbine as its main engine. Since 1980 the

US Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...

has operated the

M1 Abrams The M1 Abrams is a third-generation American main battle tank designed by Chrysler Defense (now General Dynamics Land Systems) and named for General Creighton Abrams. Conceived for modern armored ground warfare and now one of the heaviest ta ...

tank, which also has a gas turbine engine. (Most tanks use reciprocating piston diesel engines.) The Swedish Stridsvagn 103 was the first tank to utilize a gas turbine as a secondary, high-horsepower "sprint" engine to augment its primary piston engine's performance. The turboshaft engines used in all these tanks have considerably fewer parts than the piston engines they replace or supplement, mechanically are very reliable, produce reduced exterior noise, and run on virtually any fuel:

petrol Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic co ...

(gasoline),

diesel fuel Diesel fuel , also called diesel oil, is any liquid fuel specifically designed for use in a diesel engine, a type of internal combustion engine in which fuel ignition takes place without a spark as a result of compression of the inlet air and t ...

, and aviation fuels. However, turboshaft engines have significantly higher fuel consumption than the diesel engines that are used in the majority of modern main battle tanks.

References

External links

* Wikibooks: Jet propulsion {{Aircraft gas turbine engine components Gas turbines Aircraft engines Motorcycle engines de:Wellenturbine

Overview

History

See also

References

External links