{"id":31988491,"date":"2026-11-09T16:30:01","date_gmt":"2026-11-09T15:30:01","guid":{"rendered":"https:\/\/migflug.com\/afterburner\/chevron-nozzles-nasa-sawtooth-jet-engine-noise-787\/"},"modified":"2026-11-09T16:30:26","modified_gmt":"2026-11-09T15:30:26","slug":"chevron-nozzles-nasa-sawtooth-jet-engine-noise-787","status":"publish","type":"post","link":"https:\/\/migflug.com\/afterburner\/fr\/chevron-nozzles-nasa-sawtooth-jet-engine-noise-787\/","title":{"rendered":"NASA Chevron Nozzles: The Sawtooth That Quieted the 787"},"content":{"rendered":"\r\n<style>.et_pb_title_container h1.entry-title { padding-top: 40px !important; }<\/style>\r\n\r\n\r\n<!-- mfsh:top -->\r\n\r\n<style>\r\n.mfsh-trigger{display:inline-flex;align-items:center;gap:10px;height:44px;padding:0 18px;margin:0 0 26px;border:2px solid 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The back edge of each engine nacelle is cut into a row of neat triangular teeth, like the rim of a saw blade someone has rolled into a cylinder. Passengers assume it is styling. Occasionally someone decides it is damage.<\/p>\r\n<p>It is neither. Those teeth are called chevrons, they came out of a NASA laboratory in Cleveland in the 1990s, and they exist to buy roughly three decibels of quiet in exchange for about a quarter of one per cent of the engine&rsquo;s thrust. That is the entire trade, and it is one of the few pieces of aerospace engineering where you can see the answer from the terminal window.<\/p>\r\n<p>What makes the chevron worth a thousand words is not that it works. It is how narrow the margin is between the version that works and the version that makes things worse.<\/p>\r\n\r\n\r\n\r\n<div style=\"background:#f5f6f8;border-left:4px solid #5C91FF;padding:18px 22px;margin:24px 0\"><p style=\"margin:0 0 10px;font-weight:700;color:#0d1117;font-size:17px\">Quick Facts<\/p><p style=\"margin:5px 0;font-size:15px;line-height:1.6\"><strong>What it is:<\/strong> A chevron: triangular serrations cut into the trailing edge of a jet engine&rsquo;s fan or core nozzle<\/p><p style=\"margin:5px 0;font-size:15px;line-height:1.6\"><strong>Where it came from:<\/strong> NASA Glenn Research Center, developed in the 1990s from military engine &ldquo;tabs&rdquo;<\/p><p style=\"margin:5px 0;font-size:15px;line-height:1.6\"><strong>Measured thrust cost:<\/strong> 0.25 per cent in NASA&rsquo;s 1998 engine tests, which the agency called negligible<\/p><p style=\"margin:5px 0;font-size:15px;line-height:1.6\"><strong>First flight tests:<\/strong> Estrella Sailport, Arizona, 26 to 28 March 2001, on a NASA Learjet 25 and a Honeywell Falcon 20<\/p><p style=\"margin:5px 0;font-size:15px;line-height:1.6\"><strong>First commercial engine:<\/strong> The General Electric CF34-8, flown on a Bombardier CRJ900 in 2003<\/p><p style=\"margin:5px 0;font-size:15px;line-height:1.6\"><strong>Airliners that wear them:<\/strong> Boeing 787 Dreamliner, Boeing 747-8 and Boeing 737 MAX<\/p><p style=\"margin:5px 0;font-size:15px;line-height:1.6\"><strong>Flight-test benefit:<\/strong> Up to roughly 2 dB in the low-frequency aft arc on the Quiet Technology Demonstrator 2 programme<\/p><p style=\"margin:5px 0;font-size:15px;line-height:1.6\"><strong>QTD2 partners:<\/strong> Boeing, General Electric, Goodrich, NASA and All Nippon Airways<\/p><\/div>\r\n\r\n\r\n\r\n<h2 style=\"padding-top:22px\">From Military Tabs to a Sawtooth<\/h2>\r\n<p>The starting point was not elegant. Engineers had found that small tabs projecting into an engine&rsquo;s exhaust cut the noise, by helping mix the hot air coming out of the core with the cooler air coming through the fan. Mixing the two streams faster meant the jet slowed down faster, and a slower jet is a quieter jet.<\/p>\r\n<p>Tabs worked. They were also crude. In the 1990s, according to NASA&rsquo;s own account of the programme, Glenn Research Center researcher Dennis Huff and his colleagues found that a serrated, sawtooth shape did the same job better. They called it a chevron.<\/p>\r\n<p>What followed was years of unglamorous testing at Glenn&rsquo;s Aero-Acoustic Propulsion Laboratory: extensive work in the spring of 1997, then engine tests in 1998 that ran through fourteen separate chevron designs. Those 1998 tests produced the number that made the whole idea viable. The chevron nozzle cost 0.25 per cent of thrust. NASA described the reduction as negligible, and in an industry where a tenth of a per cent of specific fuel consumption is worth arguing about, that is the highest praise an add-on can get.<\/p>\r\n<p>Huff&rsquo;s own way of describing the acoustic benefit was a three-decibel reduction, which he likened to the difference between hearing two lawnmowers and hearing one. It sounds modest. In community noise terms, around an airport, it is not.<\/p>\r\n\r\n\r\n\r\n<div style=\"position:relative;padding-bottom:56.25%;height:0;overflow:hidden;margin:24px 0\"><iframe class=\"skip-lazy\" data-no-lazy=\"1\" loading=\"eager\" src=\"https:\/\/www.youtube.com\/embed\/xnjIFKNalCg\" style=\"position:absolute;top:0;left:0;width:100%;height:100%;border:0\" allowfullscreen><\/iframe><\/div>\r\n\r\n\r\n\r\n<h2 style=\"padding-top:22px\">Estrella Sailport, March 2001<\/h2>\r\n<p>A wind tunnel is not an aeroplane. To prove the chevron in the air, NASA took two aircraft to Estrella Sailport, a gliding field southwest of Phoenix, and flew them between 26 and 28 March 2001, with the first sortie on the 27th. One was NASA&rsquo;s own Learjet 25, powered by a variation of General Electric&rsquo;s J-85 turbojet. The other was a Honeywell Falcon 20 with turbofans.<\/p>\r\n<p>NASA pilot Bill Rieke, then chief of Flight Operations at Glenn, flew the Learjet; an FAA pilot, Ellen Tom, was also involved in the campaign. The team behind the work, drawn from Glenn, NASA Langley and Honeywell, took an innovation award for it in 2002.<\/p>\r\n<p>Two years later the technology was in a certificated product. The FAA began certifying General Electric&rsquo;s CF34-8 as the first commercial aircraft engine to incorporate chevrons, and it flew on a Bombardier CRJ900 in 2003. A regional jet, not a flagship. Chevrons reached the 787 and the 747-8 by way of the GEnx, and the 737 MAX by way of its own nacelle, but a CRJ got there first.<\/p>\r\n\r\n\r\n\r\n<h2 style=\"padding-top:22px\">What the Sawtooth Actually Does to the Jet<\/h2>\r\n<p>The clearest technical description of the mechanism comes from the flight-test paper written for Boeing&rsquo;s Quiet Technology Demonstrator 2 programme, and it is worth reading slowly, because every clause is doing work.<\/p>\r\n\r\n\r\n\r\n<div style=\"background:#f8f9fa;border-left:4px solid #5C91FF;padding:20px 22px;margin:18px 0 24px;font-size:16px;line-height:1.7\"><em>&ldquo;Uniform triangular serrations in the nozzle trailing edge which immerse slightly into the inner stream &hellip; an array of streamwise vorticity into the shear layer.&rdquo;<\/em><div style=\"margin-top:10px;font-size:14px;color:#555\"><strong>Quiet Technology Demonstrator 2 flight-test paper<\/strong> &mdash; Nesbitt, Mengle and Czech (Boeing), Callendar (GE) and Thomas (NASA Langley)<\/div><\/div>\r\n\r\n\r\n\r\n<p>Unpack that and the device stops being mysterious. Each tooth bends slightly inward, into the faster stream. Because the teeth alternate with gaps, the edge no longer sheds a single smooth shear layer; it sheds a ring of counter-rotating corkscrew vortices running downstream.<\/p>\r\n<p>Those vortices promote increased mixing between the two streams. The jet plume gets shorter. The velocity along its centreline falls away sooner. And since low-frequency jet mixing noise is generated by the long, fast, turbulent column of air behind the engine, shortening that column takes the noise with it.<\/p>\r\n<p>So far, so good. Here is the part that makes chevron design difficult rather than obvious.<\/p>\r\n\r\n\r\n\r\n<div style=\"background:#f8f9fa;border-left:4px solid #d32f2f;padding:20px 22px;margin:18px 0 24px;font-size:16px;line-height:1.7\"><em>&ldquo;Greater chevron immersion leads to increased low frequency noise reduction. However, increased immersion also leads to increased high frequency noise as turbulence levels are increased near the nozzle exit.&rdquo;<\/em><div style=\"margin-top:10px;font-size:14px;color:#555\"><strong>Quiet Technology Demonstrator 2 flight-test paper<\/strong> &mdash; Boeing, General Electric and NASA Langley, on the chevron immersion trade<\/div><\/div>\r\n\r\n\r\n\r\n<figure class=\"wp-block-image size-large\" style=\"margin:0 0 24px;width:100%\"><img decoding=\"async\" class=\"skip-lazy\" data-no-lazy=\"1\" loading=\"eager\" width=\"1024\" src=\"https:\/\/migflug.com\/afterburner\/wp-content\/uploads\/sites\/4\/2026\/11\/boeing-747-8f-genx-engines-chevrons-1.jpg\" alt=\"GEnx engines with chevron nozzles on a Boeing 747-8F on approach\" style=\"width:100%;height:auto;max-width:100%;display:block\"><figcaption style=\"font-size:13px;color:#777;text-align:center;margin-top:6px;font-style:italic\">GEnx-2B engines on a Nippon Cargo Airlines Boeing 747-8F. The sawtooth trailing edges on both nacelles are visible against the fuselage.<\/figcaption><\/figure>\r\n\r\n\r\n\r\n<p>Push the teeth deeper into the stream and you win more at the bottom of the spectrum and lose more at the top. A chevron is therefore not a shape you optimise; it is a shape you balance. The programme&rsquo;s stated goal was to increase or maintain the low-frequency benefit while reducing or eliminating the high-frequency increase, which is a polite way of saying that earlier chevrons had been robbing one part of the spectrum to pay another.<\/p>\r\n<h2 style=\"padding-top:22px\">A 777 Over Montana<\/h2>\r\n<p>The answer Boeing and its partners arrived at was to stop making the teeth all the same.<\/p>\r\n<p>An engine hanging under a wing does not radiate noise symmetrically. The pylon, the wing above it and the flaps behind it all interfere with the jet, which is why the field has its own acronym: propulsion airframe aeroacoustics. If the installation is asymmetric, the paper argued, the fix should be too. Tailoring the chevrons to produce enhanced mixing near the pylon reduced both the installation interaction and the jet mixing noise more than conventional azimuthally uniform chevrons could.<\/p>\r\n<p>In practice the chosen design has larger and more deeply immersed teeth close to the strut and smaller, shallower ones away from it. One nozzle, two different chevron geometries around its circumference, chosen because that combination gave the low-frequency reduction without the high-frequency penalty.<\/p>\r\n\r\n\r\n\r\n<p>Proving it needed an aeroplane. Quiet Technology Demonstrator 2 was a Boeing-led project with General Electric, Goodrich&rsquo;s Aerostructures division, NASA and All Nippon Airways, and the testbed was a Boeing 777-300ER with GE90-115B engines. The flying was done over three weeks at Boeing&rsquo;s test facility at Glasgow, Montana, a place chosen largely because there is very little there to make noise of its own.<\/p>\r\n\r\n\r\n\r\n<div style=\"background:#f8f9fa;border-left:4px solid #1565c0;padding:20px 22px;margin:18px 0 24px;font-size:16px;line-height:1.7\"><em>&ldquo;Together with our partners, GE will test several new technologies on the GE90 engines powering the QTD 2 demonstrator.&rdquo;<\/em><div style=\"margin-top:10px;font-size:14px;color:#555\"><strong>Gareth Richards<\/strong> &mdash; GE90 Program Manager, General Electric, 10 August 2005<\/div><\/div>\r\n\r\n\r\n\r\n<figure class=\"wp-block-image size-large\" style=\"margin:0 0 24px;width:100%\"><img decoding=\"async\" class=\"skip-lazy\" data-no-lazy=\"1\" loading=\"eager\" width=\"1024\" src=\"https:\/\/migflug.com\/afterburner\/wp-content\/uploads\/sites\/4\/2026\/11\/thai-airways-boeing-777-300er-ge90-115b-arlanda.jpg\" alt=\"GE90-115B engine on a Thai Airways Boeing 777-300ER\" style=\"width:100%;height:auto;max-width:100%;display:block\"><figcaption style=\"font-size:13px;color:#777;text-align:center;margin-top:6px;font-style:italic\">A GE90-115B on a Boeing 777-300ER. The QTD2 flight tests used this aircraft and engine combination, fitted with experimental fan and core chevrons.<\/figcaption><\/figure>\r\n\r\n\r\n\r\n<p>Chevrons were not the only thing on the aeroplane. GE also fitted a one-piece acoustic inlet liner running uninterrupted from the lip to the fan blades, in place of the segmented liner the GE90 normally carries, and treated the inlet lip itself rather than leaving it hard-walled.<\/p>\r\n<p>The flight results were measured, not marketed. With the tailored fan chevrons and core chevrons fitted, the aft-arc microphones recorded a significant reduction of up to roughly 2 dB in the low frequencies, at both maximum takeoff power and the reduced cutback setting. Integrated across the aft arc, the benefit held up to and including the one-third-octave band centred near 400 Hz. The paper also notes that flight data scatter can run over 2 dB from one angle to the next, which is the sort of caveat you only find in papers written by people who expect to be checked.<\/p>\r\n<p>On the cruise side, the abstract records hardly any impact on the cruise thrust coefficient. Which is the whole argument for the device: if the penalty were real, nobody would fly it.<\/p>\r\n\r\n\r\n\r\n<div style=\"position:relative;padding-bottom:56.25%;height:0;overflow:hidden;margin:24px 0\"><iframe class=\"skip-lazy\" data-no-lazy=\"1\" loading=\"eager\" src=\"https:\/\/www.youtube.com\/embed\/Sf6H8kSunRA\" style=\"position:absolute;top:0;left:0;width:100%;height:100%;border:0\" allowfullscreen><\/iframe><\/div>\r\n\r\n\r\n\r\n<h2 style=\"padding-top:22px\">Where You See Them, and Where You Do Not<\/h2>\r\n<p>Walk a modern apron and the pattern is easy to read once you know it. The 787 and the 747-8, both GEnx-powered, wear chevrons. So does the 737 MAX. Look at a Boeing 777X and its GE9X nacelles are smooth.<\/p>\r\n<p>The reason is in the physics the QTD2 paper spells out. Chevrons attack one specific noise source: the low-frequency mixing noise of a fast jet column behind the engine. The faster that jet, the more there is to attack. Very high bypass ratio engines move far more air far more slowly, which means the exhaust leaves at a lower velocity and jet mixing noise is simply a smaller part of the total. Spend thrust fixing a problem that has already shrunk and you are paying for nothing.<\/p>\r\n<p>That is the engineering logic, and it is sound. It is worth being honest that it is not the same thing as a manufacturer&rsquo;s statement. Figures circulate online for exactly what Boeing decided the 777X chevrons were costing, and none of them traces back to a published GE or Boeing document that can be checked. The number that can be checked is NASA&rsquo;s: 0.25 per cent of thrust, measured on a test stand in 1998, on the designs NASA tested. Treat anything more precise about a specific modern engine with suspicion until somebody publishes it.<\/p>\r\n\r\n\r\n\r\n<div style=\"position:relative;padding-bottom:56.25%;height:0;overflow:hidden;margin:24px 0\"><iframe class=\"skip-lazy\" data-no-lazy=\"1\" loading=\"eager\" src=\"https:\/\/www.youtube.com\/embed\/S1ahHWXGx5Y\" style=\"position:absolute;top:0;left:0;width:100%;height:100%;border:0\" allowfullscreen><\/iframe><\/div>\r\n\r\n\r\n\r\n<h2 style=\"padding-top:22px\">A Quarter of a Per Cent, Well Spent<\/h2>\r\n<p>The chevron is a good argument against the idea that aerospace progress arrives in large pieces. Nobody redesigned an engine. Somebody cut triangles into the back of a nacelle, spent years working out how deep to cut them and in what pattern, and bought a few decibels for a fraction of a per cent.<\/p>\r\n<p>What makes it a satisfying piece of engineering is that the penalty is visible and the benefit is audible, and the two are tied together by one variable. Cut the teeth deeper and the low rumble fades while a hiss comes up behind it. Cut them shallower and the rumble stays. The right answer is somewhere in between and it is different on every installation, which is why Boeing ended up flying a nozzle whose teeth change size as they go round.<\/p>\r\n<p>Next time a Dreamliner rolls past and the back of the engine looks like it has been through a bandsaw, that is what you are looking at: a 1990s laboratory result, a gliding field in Arizona, three days of flight test, and a quarter of a per cent of thrust, still being spent on every departure.<\/p>\r\n\r\n\r\n<p><em>Sources: NASA Glenn Research Center, &ldquo;NASA&rsquo;s Chevron Technology Quiets the Skies&rdquo; by Robert S. Arrighi (11 March 2025); Nesbitt, Mengle, Czech, Callendar and Thomas, &ldquo;Flight Test Results for Uniquely Tailored Propulsion-Airframe Aeroacoustic Chevrons&rdquo;, NASA Technical Reports Server; General Electric press release, &ldquo;GE and Boeing Test Quieter Jet Technologies&rdquo; (10 August 2005).<\/em><\/p>\r\n\r\n<!-- mfsh:bottom -->\r\n\r\n<button type=\"button\" class=\"mfsh-trigger mfsh-bottom\" data-mfsh-placement=\"bottom\" aria-haspopup=\"dialog\"><svg><use href=\"#mfsh-i-share\"\/><\/svg>Share this story<\/button>\r\n\r\n<!-- \/mfsh:bottom -->\r\n\r\n\r\n<style>.mfq{margin:34px 0 8px}.mfq h2{font:26px\/1.3 \"Gilroy semiBold\",Helvetica,Arial,sans-serif;color:#0d1117;padding-top:22px;margin:0 0 6px}.mfq .qa details{border-top:1px solid #5C91FF;margin:0;padding:0}.mfq .qa details:last-of-type{border-bottom:1px solid #e2e7ee}.mfq .qa summary{cursor:pointer;list-style:none;display:flex;justify-content:space-between;align-items:center;gap:16px;padding:22px 26px;font:18px\/1.7 \"Gilroy semiBold\",Helvetica,Arial,sans-serif;color:#0d1117}.mfq .qa summary::-webkit-details-marker{display:none}.mfq .qa summary::after{content:\"+\";font:24px Helvetica,sans-serif;color:#3568e0;flex:0 0 auto}.mfq .qa details[open] summary::after{content:\"\\2013\"}.mfq .qa details:hover summary{color:#3568e0}.mfq .qa .a{font:16px\/1.7 \"Gilroy regular\",Helvetica,Arial,sans-serif;color:#454e5e;padding:0 26px 24px}.mfq .qa .a a{color:#3568e0}@media(max-width:680px){.mfq .qa summary{padding:18px 14px;font-size:17px}.mfq .qa .a{padding:0 14px 20px}}<\/style>\r\n\r\n\r\n<section class=\"mfq\"><h2>Frequently Asked Questions<\/h2><div class=\"qa\"><details open><summary>What are the chevrons on a jet engine for?<\/summary><div class=\"a\">The triangular teeth on an engine nacelle, called chevrons, reduce low-frequency jet noise. They push streamwise vortices into the boundary between the hot core exhaust and the cooler fan air, mixing the two faster. That shortens the jet plume and drops its centreline velocity, which is where the rumble comes from.<\/div><\/details><details><summary>Who invented the chevron nozzle?<\/summary><div class=\"a\">NASA\u2019s Glenn Research Center. Work on noise-reducing engine tabs in the 1990s led Glenn researcher Dennis Huff and his colleagues to find that a serrated, sawtooth shape worked better. Testing at Glenn\u2019s Aero-Acoustic Propulsion Laboratory ran through fourteen designs in 1998 engine tests alone.<\/div><\/details><details><summary>How much noise do chevrons actually save?<\/summary><div class=\"a\">NASA has described the benefit as about three decibels. In the Quiet Technology Demonstrator 2 flight tests on a Boeing 777-300ER, tailored fan and core chevrons produced a reduction of up to roughly 2 dB in the low frequencies on the aft microphones, at both maximum takeoff and cutback power.<\/div><\/details><details><summary>Do chevrons cost thrust or fuel?<\/summary><div class=\"a\">A little. NASA\u2019s 1998 engine tests measured a 0.25 per cent reduction in thrust, which the agency called negligible. The QTD2 flight-test paper reports hardly any impact on the cruise thrust coefficient. The cost is real but small, which is why the devices were adopted at all.<\/div><\/details><details><summary>Why do chevrons increase high-frequency noise?<\/summary><div class=\"a\">Because the same mechanism cuts both ways. The deeper each tooth is immersed in the stream, the more low-frequency noise it removes, but the more turbulence it generates right at the nozzle exit, which raises high-frequency noise. Chevron design is a balance between the two, not an optimisation of one.<\/div><\/details><details><summary>Which airliners have chevron nozzles?<\/summary><div class=\"a\">The Boeing 787 Dreamliner, the Boeing 747-8 and the Boeing 737 MAX are the familiar ones. The first commercial engine to carry chevrons was the General Electric CF34-8, which the FAA began certifying with the technology and which flew on a Bombardier CRJ900 in 2003.<\/div><\/details><details><summary>Why does the Boeing 777X not have chevrons?<\/summary><div class=\"a\">Its GE9X nacelles are smooth. Chevrons target the mixing noise of a fast exhaust jet, and very high bypass ratio engines move much more air at much lower velocity, so that noise source is already smaller. Neither GE nor Boeing has published a verifiable figure for the trade on this engine.<\/div><\/details><details><summary>Do the jets MiGFlug flies have chevron nozzles?<\/summary><div class=\"a\">No. MiGFlug operates ex-military jets whose engines were designed decades before chevrons existed, and most of them are low-bypass turbojets or turbofans with no fan nozzle to serrate. The current aircraft, locations and prices are listed on the <a href=\"https:\/\/migflug.com\/flights-prices\/\">MiGFlug flights and prices page<\/a>.<\/div><\/details><\/div><\/section>\r\n\r\n\r\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"What are the chevrons on a jet engine for?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"The triangular teeth on an engine nacelle, called chevrons, reduce low-frequency jet noise. They push streamwise vortices into the boundary between the hot core exhaust and the cooler fan air, mixing the two faster. That shortens the jet plume and drops its centreline velocity, which is where the rumble comes from.\"}},{\"@type\":\"Question\",\"name\":\"Who invented the chevron nozzle?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"NASA\u2019s Glenn Research Center. Work on noise-reducing engine tabs in the 1990s led Glenn researcher Dennis Huff and his colleagues to find that a serrated, sawtooth shape worked better. Testing at Glenn\u2019s Aero-Acoustic Propulsion Laboratory ran through fourteen designs in 1998 engine tests alone.\"}},{\"@type\":\"Question\",\"name\":\"How much noise do chevrons actually save?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"NASA has described the benefit as about three decibels. In the Quiet Technology Demonstrator 2 flight tests on a Boeing 777-300ER, tailored fan and core chevrons produced a reduction of up to roughly 2 dB in the low frequencies on the aft microphones, at both maximum takeoff and cutback power.\"}},{\"@type\":\"Question\",\"name\":\"Do chevrons cost thrust or fuel?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"A little. NASA\u2019s 1998 engine tests measured a 0.25 per cent reduction in thrust, which the agency called negligible. The QTD2 flight-test paper reports hardly any impact on the cruise thrust coefficient. The cost is real but small, which is why the devices were adopted at all.\"}},{\"@type\":\"Question\",\"name\":\"Why do chevrons increase high-frequency noise?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Because the same mechanism cuts both ways. 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The current aircraft, locations and prices are listed on the MiGFlug flights and prices page.\"}}]}<\/script><div style=\"background:#f0f4ff;border-left:4px solid #5C91FF;padding:16px 20px;margin:32px 0 8px\"><p style=\"margin:0 0 8px;font-weight:600;color:#333\">Related Posts<\/p><p style=\"margin:4px 0\"><a href=\"https:\/\/migflug.com\/afterburner\/turbojet-vs-turbofan-vs-turboprop-turboshaft-bypass-ratio-explained\/\">Turbojet vs Turbofan vs Turboprop: How Jet Engines Differ<\/a><\/p><p style=\"margin:4px 0\"><a href=\"https:\/\/migflug.com\/afterburner\/hush-house-how-air-forces-silence-a-jet-engine\/\">Hush House: How Air Forces Run a Jet Engine at Full Afterburner Indoors<\/a><\/p><p style=\"margin:4px 0\"><a href=\"https:\/\/migflug.com\/afterburner\/airbus-a380-open-fan-flightlab-msn-114-msn-094-2026\/\">Two A380s, Two Fates: One Flies the Open Fan, One Is Scrapped<\/a><\/p><\/div>\r\n","protected":false},"excerpt":{"rendered":"<p>The triangular teeth on a 787 engine came out of a NASA laboratory in the 1990s. They buy about three decibels of quiet for a quarter of a per cent of thrust.<\/p>","protected":false},"author":23,"featured_media":31986765,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"editor_notices":[],"footnotes":""},"categories":[665],"tags":[],"class_list":["post-31988491","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-aviation-world"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.8 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>NASA Chevron Nozzles: The Sawtooth on a 787 | MiGFlug<\/title>\n<meta name=\"description\" content=\"Chevron nozzles came out of NASA Glenn in the 1990s. 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