{"id":7760,"date":"2024-03-30T21:02:07","date_gmt":"2024-03-30T13:02:07","guid":{"rendered":"https:\/\/tommykwan.com\/blog\/?p=7760"},"modified":"2024-08-21T22:56:47","modified_gmt":"2024-08-21T14:56:47","slug":"whats-coffin-corner","status":"publish","type":"post","link":"https:\/\/tommykwan.com\/blog\/aviation\/whats-coffin-corner\/","title":{"rendered":"What&#8217;s coffin corner?"},"content":{"rendered":"<p>Reference\uff1a<a href=\"https:\/\/airwaysmag.com\/coffin-corner-aviation\/\">https:\/\/airwaysmag.com\/coffin-corner-aviation\/<\/a> , <a href=\"https:\/\/www.boldmethod.com\/learn-to-fly\/aerodynamics\/coffin-corner-where-vne-and-mmo-meet\/\">https:\/\/www.boldmethod.com\/learn-to-fly\/aerodynamics\/coffin-corner-where-vne-and-mmo-meet\/<\/a><\/p>\n<p><strong>Ans:<\/strong><\/p>\n<p><strong>Coffin Corner can be explained by using below illustration. It is talking about when when the aircraft fly to an altitude where the aircraft reduces the speed, it will stall while the aircraft increase its speed, it will over the Mmo. Therefore, the margin for error is low.The coffin corner is not exactly same for different aircraft. However, it has significance in the safety of operations.\u00a0<\/strong><\/p>\n<p>&nbsp;<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.prod.website-files.com\/65c26eeea7cdaa706d97a75c\/662e9301b3e4f33a5b963341_Coffin-Corner.svg\" alt=\"Explained: What Is the Coffin Corner?\" width=\"950\" height=\"757\" \/><\/p>\n<p>Further question &#8211; <strong>please explain more about the illustration?<\/strong><\/p>\n<p style=\"text-align: center;\"><span style=\"color: #ff0000;\">Lift formula <\/span>= <span style=\"color: #ff0000;\">CL<\/span> * S * 1\/2 * <span style=\"color: #ff0000;\">air den <\/span>* <span style=\"color: #ff0000;\">V^2<\/span><\/p>\n<p>Fly <strong>higher<\/strong>, the <strong>air den drop<\/strong>, to maintain the same amount of lift, the <span style=\"color: #ff0000;\">AoA<\/span> need to increase <span style=\"color: #ff0000;\">or<\/span> compensate by increase the <span style=\"color: #ff0000;\">TAS.<\/span><\/p>\n<p>&nbsp;<\/p>\n<p>For <strong>left hand line (<span style=\"color: #ff0000;\">Vs<\/span>):<\/strong><\/p>\n<p>Since the wing will only stall when it reach critical AoA! When <span style=\"color: #ff0000;\"><strong>fly higher<\/strong><\/span>, the<span style=\"color: #ff0000;\"><strong> TAS must be higher<\/strong><\/span> to generate same amount of lift, so the <strong>so-called <span style=\"color: #ff0000;\">Vs (stall speed)<\/span><\/strong> will<span style=\"color: #ff0000;\"><strong> increase! <\/strong><\/span>(explained by Lift formula)<\/p>\n<p>&nbsp;<\/p>\n<p>For <strong>right hand line (<span style=\"color: #ff0000;\">Vmo<\/span>):<\/strong><\/p>\n<p>In <span style=\"color: #ff0000;\"><strong>commercial airline industry!!!<\/strong><\/span> We usually <span style=\"color: #ff0000;\"><strong>use(fly) Mach number at high altitude. <\/strong><\/span><\/p>\n<p>The problem comes:<\/p>\n<p style=\"text-align: center;\"><span style=\"color: #ff0000;\"><strong>Mach Number (MN) = TAS\/LSS<\/strong><\/span><\/p>\n<p style=\"text-align: center;\"><span style=\"color: #ff0000;\"><strong>LSS is affected by temperature and air den<\/strong><\/span><\/p>\n<p>Fly higher, TAS increases is must, as mentioned before, and the LSS will decrease which means the MN will higher (eg 4\/2 is 2 and 6\/1 is 6), so when fly higher, the MN is actually higher which mean it is more easy to reach the so called Mach crit<\/p>\n<p><a href=\"https:\/\/airwaysmag.com\/wp-content\/uploads\/2023\/04\/Transonic_flow_patterns.svg\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone\" src=\"https:\/\/airwaysmag.com\/wp-content\/uploads\/2023\/04\/Transonic_flow_patterns.svg\" alt=\"By U.S. Federal Aviation Administration - Airplane Flying Handbook. U.S. Government Printing Office, Washington D.C.: U.S. Federal Aviation Administration, p. 15-7. FAA-8083-3A., Public Domain, https:\/\/commons.wikimedia.org\/w\/index.php?curid=17930817\" width=\"286\" height=\"234\" \/><\/a><\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<div class=\"embed-container\"><iframe loading=\"lazy\" title=\"How HIGH CAN PLANES fly? What is the COFFIN CORNER? Explained by CAPTAIN JOE\" width=\"1170\" height=\"658\" src=\"https:\/\/www.youtube.com\/embed\/6vN1ammihDs?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/div>\n","protected":false},"excerpt":{"rendered":"<p>Reference\uff1ahttps:\/\/airwaysmag.com\/coffin-corner-aviation\/ , https:\/\/www.boldmethod.com\/learn-to-fly\/aerodynamics\/coffin-corner-where-vne-and-mmo-meet\/ Ans: Coffin Corner can be explained by using below illustration. It is talking about when when the aircraft fly to an altitude where the aircraft reduces the speed, it will stall while the aircraft increase its speed, it will over the Mmo. Therefore, the margin for error is low.The coffin corner is<a class=\"read-more \" href=\"https:\/\/tommykwan.com\/blog\/aviation\/whats-coffin-corner\/\" title=\"Read More\"> <span class=\"button default\">Read More<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[68,64,65],"tags":[],"class_list":["post-7760","post","type-post","status-publish","format-standard","hentry","category-atpl-knowledge","category-aviation","category-bak"],"_links":{"self":[{"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/posts\/7760","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/comments?post=7760"}],"version-history":[{"count":7,"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/posts\/7760\/revisions"}],"predecessor-version":[{"id":9226,"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/posts\/7760\/revisions\/9226"}],"wp:attachment":[{"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/media?parent=7760"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/categories?post=7760"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/tags?post=7760"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}