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<title>Variable cycle engine</title>

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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Variable cycle engine</span></span>

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<p>A <b>variable cycle engine</b> (<b>VCE</b>), also referred to as <b>adaptive cycle engine</b> (<b>ACE</b>), is an aircraft <a href="Jet_engine" title="Jet engine">jet engine</a> that is designed to operate efficiently under mixed flight conditions, such as <a href="Subsonic_flight" class="mw-redirect" title="Subsonic flight">subsonic</a>, <a href="Transonic" title="Transonic">transonic</a> and <a href="Supersonic" class="mw-redirect" title="Supersonic">supersonic</a>.

</p><p>An <b>advanced technology engine</b> is a turbine engine that allows different turbines to spin at different, individually optimum speeds, instead of at one speed for all.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> It emerged on larger airplanes, before finding other applications.

</p><p>The next generation of <a href="Supersonic_transport" title="Supersonic transport">supersonic transport</a> (SST) may require some form of VCE. To reduce aircraft <a href="Aerodynamic_drag" class="mw-redirect" title="Aerodynamic drag">drag</a> at <a href="Supercruise" title="Supercruise">supercruise</a>, SST engines require a high <a href="Specific_thrust" title="Specific thrust">specific thrust</a> (net thrust/airflow) to minimize the powerplant's cross-sectional area. This implies a high jet velocity supersonic cruise and at take-off, which makes the aircraft noisy.

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<div class="mw-heading mw-heading2"><h2 id="Specific_thrust">Specific thrust</h2></div>

<p>A high specific thrust engine has a high jet velocity by definition, as implied by the approximate equation for net thrust:<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

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<annotation encoding="application/x-tex">{\displaystyle F_{\text{n}}={\dot {m}}\left(V_{\text{jfe}}-V_{\text{a}}\right)}</annotation>

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</math></span><img src="./335f13a536edb0344afe3378dae4effa5fc4e83d.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:18.55ex; height:3.009ex;" alt="{\displaystyle F_{\text{n}}={\dot {m}}\left(V_{\text{jfe}}-V_{\text{a}}\right)}" loading="lazy"></span></dd></dl>

<p>where:

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<annotation encoding="application/x-tex">{\textstyle {\dot {m}}={\frac {d}{dt}}m,\,}</annotation>

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</math></span><img src="./6bcebbf4134b8513f30a6376325bc3151b969a38.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.338ex; width:10.503ex; height:3.843ex;" alt="{\textstyle {\dot {m}}={\frac {d}{dt}}m,\,}" loading="lazy"></span> intake mass flow rate</dd>

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<annotation encoding="application/x-tex">{\displaystyle V_{\text{jfe}},\,}</annotation>

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</math></span><img src="./19bb1e06a308ec3c3a9e8b9443a0ca0f020ac266.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:4.358ex; height:2.843ex;" alt="{\displaystyle V_{\text{jfe}},\,}" loading="lazy"></span> fully expanded jet velocity (in the exhaust plume)</dd>

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<annotation encoding="application/x-tex">{\displaystyle V_{\text{a}},\,}</annotation>

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</math></span><img src="./e448f73b689a49bd0360b63f9d69373c45b85955.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.443ex; height:2.509ex;" alt="{\displaystyle V_{\text{a}},\,}" loading="lazy"></span> aircraft flight velocity</dd></dl>

<p>Rearranging the equation, specific thrust is given by:

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<annotation encoding="application/x-tex">{\displaystyle {\frac {F_{\text{n}}}{\dot {m}}}=V_{\text{jfe}}-V_{\text{a}}}</annotation>

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</math></span><img src="./16f73f2d7f60e3bf41fc6707607814a091e57eb8.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.838ex; width:15.149ex; height:5.176ex;" alt="{\displaystyle {\frac {F_{\text{n}}}{\dot {m}}}=V_{\text{jfe}}-V_{\text{a}}}" loading="lazy"></span></dd></dl>

<p>So for zero flight velocity, specific thrust is directly proportional to jet velocity.

</p><p>The <a href="Rolls-Royce/Snecma_Olympus_593" title="Rolls-Royce/Snecma Olympus 593">Rolls-Royce/Snecma Olympus 593</a> in <a href="Concorde" title="Concorde">Concorde</a> had a high specific thrust in supersonic cruise and at dry take-off. This made the engines noisy. The problem was compounded by the need for a modest amount of <a href="Afterburner" title="Afterburner">afterburning</a> (reheat) at take-off (and transonic acceleration).

</p>

<div class="mw-heading mw-heading2"><h2 id="Concepts">Concepts</h2></div>

<div class="mw-heading mw-heading3"><h3 id="Tandem_fan">Tandem fan</h3></div>

<p>One SST VCE concept is the tandem fan engine. The engine has two fans, both mounted on the low-pressure shaft, separated by a significant axial gap. The engine operates in series mode while cruising and parallel mode take-off, climb-out, approach, and final-descent.

</p><p>In series mode, air enters in the front of the engine. After passing through the front fan, the air passes directly into the second fan, so that the engine behaves much like a <a href="Turbofan" title="Turbofan">turbofan</a>.

</p><p>In parallel mode, air leaving the front fan exits the engine through an auxiliary nozzle on the underside of the <a href="Nacelle" title="Nacelle">nacelle</a>, skipping the rear fan. Intakes on each side of the engine open to capture air and send it directly to the rear fan and the rest of the engine. Parallel mode substantially increases the total air accelerated by the engine, lowering the velocity of the air and accompanying noise.

</p><p>In the 1970s, <a href="Boeing" title="Boeing">Boeing</a> modified a <a href="Pratt_%26_Whitney_JT8D" title="Pratt & Whitney JT8D">Pratt & Whitney JT8D</a> to use a tandem fan configuration and successfully demonstrated the switch from series to parallel operation (and vice versa) with the engine running, albeit at partial power.

</p>

<div class="mw-heading mw-heading3"><h3 id="Mid-tandem_fan">Mid-tandem fan</h3></div>

<p>In the mid-tandem fan concept, a high specific flow single stage fan is located between the high pressure (HP) and low pressure (LP) compressors of a <a href="Turbojet" title="Turbojet">turbojet</a> core. Only bypass air passes through the fan. The LP compressor exit flow passes through passages within the fan disc, directly underneath the fan blades. Some bypass air enters the engine via an auxiliary intake. During take-off and approach the engine behaves much like a conventional turbofan, with an acceptable jet noise level (i.e., low specific thrust). However, for <a href="Supercruise" title="Supercruise">supersonic cruise</a>, the fan variable inlet guide vanes and auxiliary intake close to minimize bypass flow and increase specific thrust. In this mode the engine acts more like a 'leaky' turbojet (e.g. the <a href="General_Electric_F404" title="General Electric F404">F404</a>).

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<div class="mw-heading mw-heading3"><h3 id="Mixed-flow_turbofan_ejector">Mixed-flow turbofan ejector</h3></div>

<p>In the mixed-flow turbofan with ejector concept, a low bypass ratio engine is mounted in front of a long tube, called an ejector. The ejector reduces noise. It is deployed during take-off and approach. Turbofan exhaust gases send air into the ejector via an auxiliary air intake, thereby reducing the specific thrust/mean jet velocity of the final exhaust. The mixed-flow design is not particularly efficient at low speed, but is considerably simpler.

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<div class="mw-heading mw-heading3"><h3 id="Three_stream">Three stream</h3></div>

<p>The three-stream architecture adds a third, directable air stream. This stream bypasses the core when <a href="Fuel_efficiency" title="Fuel efficiency">fuel efficiency</a> is required or through the core for greater power. Under the Versatile Affordable Advanced Turbine Engines (VAATE) program, the U.S Air Force and industry partners developed this concept under the <a href="Adaptive_Versatile_Engine_Technology" title="Adaptive Versatile Engine Technology">Adaptive Versatile Engine Technology</a> (ADVENT) and the follow-on Adaptive Engine Technology Demonstrator (AETD) and Adaptive Engine Transition Program (AETP) programs.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> Examples include the <a href="General_Electric_XA100" title="General Electric XA100">General Electric XA100</a> and the <a href="Pratt_%26_Whitney_XA101" title="Pratt & Whitney XA101">Pratt & Whitney XA101</a>, as well as the propulsion system for the <a href="Next_Generation_Air_Dominance" title="Next Generation Air Dominance">Next Generation Air Dominance</a> (NGAD) fighter.<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup>

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<div class="mw-heading mw-heading3"><h3 id="Double_bypass">Double bypass</h3></div>

<p><a href="General_Electric" title="General Electric">General Electric</a> developed a variable cycle engine, known as the GE37 or <a href="General_Electric_YF120" title="General Electric YF120">General Electric YF120</a>, for the <a href="Lockheed_YF-22" title="Lockheed YF-22">YF-22</a>/<a href="Northrop_YF-23" title="Northrop YF-23">YF-23</a> fighter aircraft competition, in the late 1980s. GE used a double bypass/hybrid fan arrangement, but never disclosed how they exploited the concept. The Air Force instead selected the conventional <a href="Pratt_%26_Whitney_F119" title="Pratt & Whitney F119">Pratt & Whitney F119</a> for what became the <a href="Lockheed_Martin_F-22_Raptor" title="Lockheed Martin F-22 Raptor">Lockheed Martin F-22 Raptor</a>.

</p>

<div class="mw-heading mw-heading3"><h3 id="Other_geared_turbofans">Other geared turbofans</h3></div>

<p><a href="Geared_turbofan" title="Geared turbofan">Geared turbofans</a> are also used in the following engines, some still in development: <a href="Garrett_TFE731" title="Garrett TFE731">Garrett TFE731</a>, <a href="Lycoming_ALF_502" title="Lycoming ALF 502">Lycoming ALF 502</a>/<a href="Honeywell_LF_507" class="mw-redirect" title="Honeywell LF 507">LF 507</a>, <a href="Pratt_%26_Whitney_PW1000G" title="Pratt & Whitney PW1000G">Pratt & Whitney PW1000G</a>, <a href="Turbomeca_Astafan" title="Turbomeca Astafan">Turbomeca Astafan</a>, and <a href="Turbomeca_Aspin" title="Turbomeca Aspin">Turbomeca Aspin</a>, and <a href="Aviadvigatel" title="Aviadvigatel">Aviadvigatel</a> PD-18R.

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<div class="mw-heading mw-heading3"><h3 id="Rolls_Royce_Ultrafan">Rolls Royce Ultrafan</h3></div>

<p>The <a href="Rolls-Royce_Trent" title="Rolls-Royce Trent">Rolls Royce Ultrafan</a> is the largest and most efficient engine to allow multiple turbine speeds. The turbines behind the main fan are small and allow more air to pass straight through, while a planetary gearbox "allows the main fan to spin slower and the compressors to spin faster, putting each in their optimal zones."<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup>

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<div class="mw-heading mw-heading3"><h3 id="Turboelectric">Turboelectric</h3></div>

<p>Startup Astro Mechanica is developing what it calls a turboelectric-adaptive jet engine that shifts from turbofan to turbojet to <a href="Ramjet" title="Ramjet">ramjet</a> mode as it accelerates from a standing start to a projected <a href="Hypersonic_speed" title="Hypersonic speed">Mach 6</a>. This is achieved by using a dual turbine approach. One turbine acts as an <a href="Turbo_generator" title="Turbo generator">turbogenerator</a>. The second turbine acts as the propulsion unit. The turbogenerator powers an electric motor that controls the compressor of the second turbine. The motor can change speeds to keep the fan turning at the ideal RPM for a specific flight mode. In turbojet and ramjet modes, the inlet is narrowed to compress the air and eliminate bypass. The turbogenerator is commercially available, while the propulsion unit is built by the company. A key innovation is that electric motors have dramatically increased their power density so that the weight of the motor is no longer prohibitive.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:0_7-0" class="reference"><a href="#cite_note-:0-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup>

</p><p>Instead of a fixed gearbox, it uses an electric motor to turn the turbine(s) behind the fan at an ideal speed for each phase of flight. The company claimed it would support efficient take-off, subsonic, supersonic, and hypersonic speeds. The electric motor is powered by a generator in turn powered by a turbine. The approach relies on the improved <a href="Power_density" title="Power density">power density</a> of novel electric motors such as yokeless dual-rotor <a href="Axial_flux_motor" title="Axial flux motor">axial flux motors</a> that offer far more kw/kg than conventional designs that were too heavy for such an application.<sup id="cite_ref-:0_7-1" class="reference"><a href="#cite_note-:0-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup>

</p><p>Air flows in through a turbogenerator to produce electric power to power an electric motor. The electric motor adaptively controls the propulsion unit, allowing it to behave like a turbofan, turbojet, or ramjet depending on airspeed. In effect the engine can operate at any point along the specific impulse (Isp) curve - high Isp at low speed or low Isp at high speed.<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:0_7-2" class="reference"><a href="#cite_note-:0-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup>

</p><p>It is in some respects similar to <a href="Marine_propulsion#Turbo-electric" title="Marine propulsion">turbo-electric marine engines</a> that allow propellers to turn at a different speed than the steam turbines that power them.

</p>

<ul><li><a href="Index_of_aviation_articles" title="Index of aviation articles">Index of aviation articles</a></li></ul>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

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</style><cite id="CITEREFWragg1973" class="citation book cs1">Wragg, David W. (1973). <i>A Dictionary of Aviation</i> (first ed.). Osprey. p. 4. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>9780850451634</bdi>.</cite></span>

</li>

<li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20060823131521/http://exploration.grc.nasa.gov/education/rocket/thrsteq.html">"Thrust equation"</a>. Archived from <a rel="nofollow" class="external text" href="https://exploration.grc.nasa.gov/education/rocket/thrsteq.html">the original</a> on 23 August 2006<span class="reference-accessdate">. Retrieved <span class="nowrap">20 March</span> 2011</span>.</cite></span>

</li>

<li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><cite id="CITEREFThomson2010" class="citation conference cs1">Thomson, Daniel E. (14 April 2010). <a rel="nofollow" class="external text" href="https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2010/SET/Thomson.pdf"><i>Versatile Affordable Advanced Turbine Engines Provide Game Changing Capability with Superior Fuel Efficiency</i></a> <span class="cs1-format">(PDF)</span>. 11th Annual Science & Engineering Technology Conference/DoD Tech Expo. Charleston, South Carolina.</cite></span>

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<li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><cite id="CITEREFMathews2017" class="citation web cs1">Mathews, Jim (26 June 2017). <a rel="nofollow" class="external text" href="https://www.airforcemag.com/article/engines-of-innovation/">"Engines of Innovation"</a>. <i>Air Force Magazine</i><span class="reference-accessdate">. Retrieved <span class="nowrap">11 January</span> 2020</span>.</cite></span>

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<li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://newatlas.com/aircraft/rolls-royce-ultrafan-testing/">"World's largest and most efficient aircraft engine aces first tests"</a>. <i>New Atlas</i>. 2023-05-22<span class="reference-accessdate">. Retrieved <span class="nowrap">2023-09-24</span></span>.</cite></span>

</li>

<li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><cite id="CITEREFMcCormick2024" class="citation web cs1">McCormick, Packy (April 1, 2024). <a rel="nofollow" class="external text" href="https://www.notboring.co/p/astro-mechanica">"Astro Mechanica - The Aerospace Company"</a>. <i>www.notboring.co</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2024-05-19</span></span>.</cite></span>

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<li id="cite_note-:0-7"><span class="mw-cite-backlink">^ <a href="#cite_ref-:0_7-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:0_7-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-:0_7-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><cite id="CITEREFKeil2024" class="citation web cs1">Keil, Christian (February 28, 2024). <a rel="nofollow" class="external text" href="https://x.com/pronounced_kyle/status/1762945945120149955?s=20">"Interview with Ian Brooke"</a>. <i>x.com</i>.</cite></span>

</li>

<li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><cite id="CITEREFCôté2024" class="citation web cs1">Côté, Andrew (February 28, 2024). <a rel="nofollow" class="external text" href="https://x.com/Andercot/status/1763063321857757210?s=20">"Astro Mechanica"</a>. <i>x.com</i><span class="reference-accessdate">. Retrieved <span class="nowrap">April 2,</span> 2024</span>.</cite></span>

</li>

<li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text"><cite id="CITEREFMcCormick2024" class="citation web cs1">McCormick, Packy (April 1, 2024). <a rel="nofollow" class="external text" href="https://www.notboring.co/p/astro-mechanica">"Astro Mechanica"</a>. <i>www.notboring.co</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2024-04-02</span></span>.</cite></span>

</li>

<li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><cite id="CITEREFCôté2024" class="citation web cs1">Côté, Andrew (February 28, 2024). <a rel="nofollow" class="external text" href="https://x.com/Andercot/status/1763063321857757210?s=20">"Astro Mechanica"</a>. <i>x.com</i><span class="reference-accessdate">. Retrieved <span class="nowrap">April 2,</span> 2024</span>.</cite></span>

</li>

</ol></div></div>

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</style><div id="Jet_engines_and_aircraft_gas_turbines283" style="font-size:114%;margin:0 4em"><a href="Jet_engine" title="Jet engine">Jet engines</a> and <a href="Aircraft_engine" title="Aircraft engine">aircraft</a> <a href="Gas_turbine" title="Gas turbine">gas turbines</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Gas_turbine" title="Gas turbine">Gas turbines</a><br> and <a href="Jet_propulsion" title="Jet propulsion">jet propulsion</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Types</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Air_turborocket" title="Air turborocket">Air turborocket</a></li>

<li><a href="Pulsejet" title="Pulsejet">Pulsejet</a>/<a href="Valveless_pulsejet" title="Valveless pulsejet">Valveless pulsejet</a>/<a href="Gluhareff_Pressure_Jet" title="Gluhareff Pressure Jet">Gluhareff Pressure Jet</a></li>

<li><a href="Pulse_detonation_engine" title="Pulse detonation engine">Pulse detonation engine</a></li>

<li><a href="Propfan" title="Propfan">Propfan</a></li>

<li><a href="Turbofan" title="Turbofan">Turbofan</a></li>

<li><a href="Turbojet" title="Turbojet">Turbojet</a></li>

<li><a href="Turboprop" title="Turboprop">Turboprop</a></li>

<li><a href="Turboshaft" title="Turboshaft">Turboshaft</a></li>

<li><a href="Ramjet" title="Ramjet">Ramjet</a></li>

<li><a href="Scramjet" title="Scramjet">Scramjet</a></li>

<li><a href="Shcramjet" title="Shcramjet">Shcramjet</a></li>

<li><a href="Rocket_engine" title="Rocket engine">Rocket</a></li>

<li><a href="Rotating_detonation_engine" title="Rotating detonation engine">Rotating detonation engine</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Mechanical<br> components</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Accessory_drive" title="Accessory drive">Accessory drive</a></li>

<li><a href="Components_of_jet_engines#Air_intakes" title="Components of jet engines">Air intake</a></li>

<li><a href="Afterburner" title="Afterburner">Afterburner (reheat)</a></li>

<li><a href="Axial_compressor" title="Axial compressor">Axial compressor</a></li>

<li><a href="Centrifugal_compressor" title="Centrifugal compressor">Centrifugal compressor</a></li>

<li><a href="Combustor" title="Combustor">Combustor</a></li>

<li><a href="Constant_speed_drive" title="Constant speed drive">Constant speed drive</a></li>

<li><a href="Impeller" title="Impeller">Impeller</a></li>

<li><a href="Nose_bullet" class="mw-redirect" title="Nose bullet">Nose bullet</a></li>

<li><a href="Propelling_nozzle" title="Propelling nozzle">Propelling nozzle</a></li>

<li><a href="Turbine_blade" title="Turbine blade">Turbine blade</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Principles</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Aircraft_engine_starting" title="Aircraft engine starting">Aircraft engine starting</a></li>

<li><a href="Bleed_air" title="Bleed air">Bleed air</a></li>

<li><a href="Brayton_cycle" title="Brayton cycle">Brayton cycle</a></li>

<li><a href="Bypass_ratio" title="Bypass ratio">Bypass ratio</a></li>

<li><a href="Compressor_stall" title="Compressor stall">Compressor stall</a></li>

<li><a href="Engine_pressure_ratio" title="Engine pressure ratio">Engine pressure ratio (EPR)</a></li>

<li><a href="Flameout" title="Flameout">Flameout</a></li>

<li><a href="Jet_engine_performance" title="Jet engine performance">Jet engine performance</a></li>

<li><a href="Overall_pressure_ratio" title="Overall pressure ratio">Overall pressure ratio</a></li>

<li><a href="Propulsive_efficiency" title="Propulsive efficiency">Propulsive efficiency</a></li>

<li><a href="Specific_impulse" title="Specific impulse">Specific impulse</a></li>

<li><a href="Thrust" title="Thrust">Thrust</a></li>

<li><a href="Thrust_lapse" class="mw-redirect" title="Thrust lapse">Thrust lapse</a></li>

<li><a href="Thrust_specific_fuel_consumption" class="mw-redirect" title="Thrust specific fuel consumption">Thrust specific fuel consumption</a></li>

<li><a href="Thrust_to_weight_ratio" class="mw-redirect" title="Thrust to weight ratio">Thrust to weight ratio</a></li>

<li><a href="Windmill_restart" class="mw-redirect" title="Windmill restart">Windmill restart</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Propeller_(aeronautics)" title="Propeller (aeronautics)">Propellers</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Components</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Propeller_governor" class="mw-redirect" title="Propeller governor">Propeller governor</a></li>

<li><a href="Propeller_speed_reduction_unit" title="Propeller speed reduction unit">Propeller speed reduction unit</a></li></ul>

<ul><li><a href="Autofeather" title="Autofeather">Autofeather</a></li>

<li><a href="Blade_pitch" title="Blade pitch">Blade pitch</a></li>

<li><a href="Constant-speed_propeller" class="mw-redirect" title="Constant-speed propeller">Constant-speed</a></li>

<li><a href="Contra-rotating_propellers" title="Contra-rotating propellers">Contra-rotating</a></li>

<li><a href="Counter-rotating_propellers" title="Counter-rotating propellers">Counter-rotating</a></li>

<li><a href="Proprotor" title="Proprotor">Proprotor</a></li>

<li><a href="Scimitar_propeller" title="Scimitar propeller">Scimitar</a></li>

<li><a href="Variable-pitch_propeller_(aeronautics)" title="Variable-pitch propeller (aeronautics)">Variable-pitch</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Engine<br> instruments</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Annunciator_panel" title="Annunciator panel">Annunciator panel</a></li>

<li><a href="Electronic_centralised_aircraft_monitor" title="Electronic centralised aircraft monitor">Electronic centralised aircraft monitor (ECAM)</a></li>

<li><a href="Electronic_flight_instrument_system" title="Electronic flight instrument system">Electronic flight instrument system (EFIS)</a></li>

<li><a href="Engine-indicating_and_crew-alerting_system" title="Engine-indicating and crew-alerting system">Engine-indicating and crew-alerting system (EICAS)</a></li>

<li><a href="Flight_data_recorder" class="mw-redirect" title="Flight data recorder">Flight data recorder</a></li>

<li><a href="Glass_cockpit" title="Glass cockpit">Glass cockpit</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Aircraft_engine_controls" title="Aircraft engine controls">Engine controls</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Autothrottle" title="Autothrottle">Autothrottle</a></li>

<li><a href="FADEC" title="FADEC">Full Authority Digital Engine/Electronics (FADEC)</a></li>

<li><a href="Thrust_lever" title="Thrust lever">Thrust lever</a></li>

<li><a href="Thrust_reversal" title="Thrust reversal">Thrust reversal</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Aircraft_fuel_system" title="Aircraft fuel system">Fuel</a> and induction<br> systems</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Flame_holder" title="Flame holder">Flame holder</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other systems</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Air-start_system" title="Air-start system">Air-start system</a></li>

<li><a href="Auxiliary_power_unit" title="Auxiliary power unit">Auxiliary power unit (APU)</a></li>

<li><a href="Bleed_air" title="Bleed air">Bleed air system</a></li>

<li><a href="Hydraulic_fluid#Aircraft_hydraulic_systems" title="Hydraulic fluid">Hydraulic system</a></li>

<li><a href="Ice_protection_system" title="Ice protection system">Ice protection system</a></li></ul>

</div></td></tr></tbody></table></div>

<div class="navbox-styles"></div><div role="navigation" class="navbox" aria-labelledby="Heat_engines39" style="padding:3px"><table class="nowraplinks mw-collapsible uncollapsed navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2" style="background:#F0DC82;"><div id="Heat_engines39" style="font-size:114%;margin:0 4em"><a href="Heat_engine" title="Heat engine">Heat engines</a></div></th></tr><tr><td colspan="2" class="navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Carnot_heat_engine" title="Carnot heat engine">Carnot engine</a></li>

<li><a href="Fluidyne_engine" title="Fluidyne engine">Fluidyne</a></li>

<li><a href="Gas_turbine" title="Gas turbine">Gas turbine</a></li>

<li><a href="Minto_wheel" title="Minto wheel">Minto wheel</a></li>

<li><a href="Photo-Carnot_engine" title="Photo-Carnot engine">Photo-Carnot engine</a></li>

<li><a href="Reciprocating_engine" title="Reciprocating engine">Piston</a></li>

<li><a href="Pistonless_rotary_engine" title="Pistonless rotary engine">Pistonless (Rotary)</a></li>

<li><a href="Rijke_tube" title="Rijke tube">Rijke tube</a></li>

<li><a href="Rocket_engine" title="Rocket engine">Rocket</a></li>

<li><a href="Split-single_engine" title="Split-single engine">Split-single</a></li>

<li><a href="Steam_engine" title="Steam engine">Steam (reciprocating)</a></li>

<li><a href="Steam_turbine" title="Steam turbine">Steam turbine</a>

<ul><li><a href="Aeolipile" title="Aeolipile">Aeolipile</a></li></ul></li>

<li><a href="Stirling_engine" title="Stirling engine">Stirling</a></li>

<li><a href="Thermoacoustic_heat_engine" title="Thermoacoustic heat engine">Thermoacoustic</a></li>

<li><a href="Manson_engine" title="Manson engine">Manson engine</a></li></ul>

</div></td></tr><tr><td colspan="2" class="navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Beale_number" title="Beale number">Beale number</a></li>

<li><a href="West_number" title="West number">West number</a></li></ul>

</div></td></tr><tr><td colspan="2" class="navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Timeline_of_heat_engine_technology" title="Timeline of heat engine technology">Timeline of heat engine technology</a></li></ul>

</div></td></tr><tr><td class="navbox-abovebelow" colspan="2" style="background:#F0DC82;"><div><a href="Thermodynamic_cycle" title="Thermodynamic cycle">Thermodynamic cycle</a></div></td></tr></tbody></table></div></div><div><div class="zim-footer">

This article is issued from <a class="external text" title="Last edited on 2024-12-15" href="https://en.wikipedia.org/wiki/?title=Variable_cycle_engine&oldid=1263314986">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.

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