{"id":2609,"date":"2025-11-14T16:32:41","date_gmt":"2025-11-14T15:32:41","guid":{"rendered":"https:\/\/acriv.org\/WP\/?page_id=2609"},"modified":"2025-11-14T16:32:41","modified_gmt":"2025-11-14T15:32:41","slug":"%f0%9f%9a%a8le-decrochage","status":"publish","type":"page","link":"https:\/\/acriv.org\/WP\/%f0%9f%9a%a8le-decrochage\/","title":{"rendered":"\ud83d\udea8LE DECROCHAGE"},"content":{"rendered":"<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"506\" height=\"600\" src=\"https:\/\/acriv.org\/WP\/wp-content\/uploads\/2025\/11\/800px-Angles_de_portance_et_de_decrochage.svg_.png\" alt=\"\" class=\"wp-image-2610\" style=\"width:299px;height:auto\" srcset=\"https:\/\/acriv.org\/WP\/wp-content\/uploads\/2025\/11\/800px-Angles_de_portance_et_de_decrochage.svg_.png 506w, https:\/\/acriv.org\/WP\/wp-content\/uploads\/2025\/11\/800px-Angles_de_portance_et_de_decrochage.svg_-253x300.png 253w, https:\/\/acriv.org\/WP\/wp-content\/uploads\/2025\/11\/800px-Angles_de_portance_et_de_decrochage.svg_-261x310.png 261w, https:\/\/acriv.org\/WP\/wp-content\/uploads\/2025\/11\/800px-Angles_de_portance_et_de_decrochage.svg_-89x105.png 89w\" sizes=\"auto, (max-width: 506px) 100vw, 506px\" \/><\/figure>\n<\/div>\n\n\n<h1 class=\"wp-block-heading\">\u2708\ufe0f 1. Qu\u2019est-ce qu\u2019un d\u00e9crochage ?<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">Un <strong>d\u00e9crochage<\/strong> n\u2019est pas une perte de vitesse, mais une <strong>perte d\u2019adh\u00e9rence a\u00e9rodynamique<\/strong> du flux d\u2019air sur le <strong>profil de l\u2019aile<\/strong>, lorsque l\u2019<strong>angle d\u2019attaque<\/strong> d\u00e9passe une valeur critique (souvent autour de 15\u00b0\u201318\u00b0 selon l\u2019aile).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">La portance chute brusquement \u2192 l\u2019avion ne peut plus compenser son poids \u2192 il commence \u00e0 descendre.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">\u2708\ufe0f 2. Que se passe-t-il physiquement ?<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\">\u2714\ufe0f 1) L\u2019angle d\u2019attaque devient trop \u00e9lev\u00e9<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Le flux d\u2019air ne suit plus le profil \u2192 <strong>d\u00e9collage tourbillonnaire<\/strong>, turbulences.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u2714\ufe0f 2) La portance chute brutalement<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">La courbe \u201cportance vs angle d\u2019attaque\u201d atteint un maximum, puis <strong>s\u2019effondre<\/strong>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u2714\ufe0f 3) La tra\u00een\u00e9e augmente tr\u00e8s fortement<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u2192 l\u2019avion ralentit encore \u2192 aggrave la situation si on tire davantage.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u2714\ufe0f 4) L\u2019aile d\u00e9croche souvent asym\u00e9triquement<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Au moindre d\u00e9faut de sym\u00e9trie (pied mal centr\u00e9),<br>\u2192 <strong>un demi-plan d\u00e9croche avant l&rsquo;autre<\/strong><br>\u2192 l\u2019avion bascule = d\u00e9but de <strong>vrille<\/strong>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u2714\ufe0f 5) Perte d\u2019efficacit\u00e9 des commandes<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Ailerons<\/strong> : moins efficaces, voire invers\u00e9s si une aile d\u00e9croche plus que l\u2019autre.<\/li>\n\n\n\n<li><strong>Profondeur<\/strong> : devient molle.<\/li>\n\n\n\n<li><strong>D\u00e9rive<\/strong> : encore efficace \u2192 cl\u00e9 de la sortie !<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">\u2708\ufe0f 3. Signes pr\u00e9curseurs du d\u00e9crochage<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">Un avion certifi\u00e9 doit montrer plusieurs alertes :<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u2714\ufe0f Pr\u00e9curseurs a\u00e9rodynamiques :<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Vibrations, buffet a\u00e9rodynamique<\/li>\n\n\n\n<li>Manche plus mou<\/li>\n\n\n\n<li>Augmentation rapide de l\u2019angle d\u2019assiette<\/li>\n\n\n\n<li>D\u00e9rapage qui devient dangereux<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">\u2714\ufe0f Pr\u00e9curseurs techniques :<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Alerte sonore (horn)<\/li>\n\n\n\n<li>Palpeur de d\u00e9crochage<\/li>\n\n\n\n<li>Bufet de la cellule<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">\u2708\ufe0f 4. D\u00e9roulement typique d\u2019un d\u00e9crochage<\/h1>\n\n\n\n<ol class=\"wp-block-list\">\n<li>L\u2019avion atteint un angle d\u2019attaque excessif.<\/li>\n\n\n\n<li>La portance s\u2019\u00e9croule \u2192 l\u2019avion <strong>s\u2019enfonce<\/strong>.<\/li>\n\n\n\n<li>Une aile d\u00e9croche souvent avant l\u2019autre \u2192 <strong>bascule<\/strong>.<\/li>\n\n\n\n<li>L\u2019assiette reste \u00e9lev\u00e9e, mais la trajectoire descend.<\/li>\n\n\n\n<li>Si aucune correction \u2192 amorce de <strong>vrille<\/strong>.<\/li>\n<\/ol>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">\u2708\ufe0f 5. Comment sortir d\u2019un d\u00e9crochage ?<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">La correction est <strong>toujours la m\u00eame<\/strong> sur tous les avions classiques :<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u2714\ufe0f 1) <strong>Diminuer l\u2019angle d\u2019attaque<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u2192 pousser l\u00e9g\u00e8rement sur le manche<br>(C\u2019est le geste cl\u00e9 : sans \u00e7a, rien ne r\u00e9cup\u00e8re.)<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u2714\ufe0f 2) <strong>Ailerons neutres<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u2192 \u00e9viter de d\u00e9crocher une aile encore plus.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u2714\ufe0f 3) <strong>Coordonner au pied<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u2192 bille centr\u00e9e pour \u00e9viter la vrille.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u2714\ufe0f 4) <strong>Remettre les gaz progressivement<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u2192 apr\u00e8s r\u00e9duction d\u2019incidence, jamais avant.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u2714\ufe0f 5) Reprendre une assiette de mont\u00e9e stabilis\u00e9e.<\/h3>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">\u2708\ufe0f 6. Influence des \u00e9quipements hypersustentateurs<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">Les <strong>\u00e9quipements hypersustentateurs<\/strong> permettent de <strong>voler plus lentement sans d\u00e9crocher<\/strong>, en retardant l\u2019apparition de l\u2019angle critique ou en augmentant la portance maximale.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Les principaux :<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Volets (flaps)<\/strong><\/li>\n\n\n\n<li><strong>Becs (slats)<\/strong><\/li>\n\n\n\n<li><strong>Fentes fixes ou mobiles (slots)<\/strong><\/li>\n\n\n\n<li><strong>Ailettes de d\u00e9crochage \/ \u00ab\u00a0stall strips\u00a0\u00bb<\/strong><\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Voici leur r\u00f4le.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">\u2708\ufe0f 7. Volets (flaps)<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">Les volets :<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>augmentent la <strong>courbure du profil<\/strong><\/li>\n\n\n\n<li>augmentent la <strong>portance maximale<\/strong><\/li>\n\n\n\n<li>permettent une <strong>vitesse de d\u00e9crochage plus basse<\/strong><\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">\u2714\ufe0f Effets positifs :<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>D\u00e9crochage <strong>plus tardif<\/strong><\/li>\n\n\n\n<li>Approche plus lente<\/li>\n\n\n\n<li>Trajectoire plus stable en finale<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">\u2714\ufe0f Effets n\u00e9gatifs :<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Forte augmentation de la <strong>tra\u00een\u00e9e<\/strong><\/li>\n\n\n\n<li>En grands d\u00e9battements : assiette modifi\u00e9e (selon avion)<\/li>\n\n\n\n<li>D\u00e9crochage plus franc si forte dissym\u00e9trie de volets<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">\u2708\ufe0f En d\u00e9crochage avec volets :<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Le d\u00e9crochage survient :<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u00e0 <strong>plus faible vitesse<\/strong>,<\/li>\n\n\n\n<li>avec un comportement parfois plus marqu\u00e9 (selon type d\u2019aile).<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">\u2708\ufe0f 8. Becs de bord d\u2019attaque (slats)<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">Les becs peuvent \u00eatre :<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>automatiques<\/strong> (ULM, avions STOL)<\/li>\n\n\n\n<li><strong>command\u00e9s<\/strong> (avions de ligne)<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Ils cr\u00e9ent un <strong>canal de r\u00e9-\u00e9nergisation<\/strong> du flux d\u2019air sur l\u2019aile.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u2714\ufe0f Effets :<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>D\u00e9placent l\u2019angle d\u2019attaque critique plus haut<\/li>\n\n\n\n<li>Permettent de voler <strong>\u00e0 tr\u00e8s forte incidence<\/strong><\/li>\n\n\n\n<li>D\u00e9crochage <strong>plus progressif<\/strong><\/li>\n\n\n\n<li>Maintien de la <strong>commande d&rsquo;ailerons<\/strong> jusqu\u2019\u00e0 des angles \u00e9lev\u00e9s<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">C\u2019est l\u2019\u00e9quipement le plus efficace pour pr\u00e9venir un d\u00e9crochage brutal.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">\u2708\ufe0f 9. Ailes \u00e0 fentes ou ailes fauch\u00e9es (slots)<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">Ce sont des \u00e9chancrures fixes vers le bord d\u2019attaque.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u2714\ufe0f R\u00f4le :<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>guident l\u2019air vers l\u2019extrados<\/li>\n\n\n\n<li>retardent le d\u00e9collement du flux<\/li>\n\n\n\n<li>am\u00e9liorent la stabilit\u00e9 \u00e0 basse vitesse<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Utilis\u00e9 sur STOL, bush planes, DR400, ULM avanc\u00e9s\u2026<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">\u2708\ufe0f 10. Stall strips (ailettes de d\u00e9crochage)<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">Petites lamelles triangulaires ajout\u00e9es sur le bord d\u2019attaque, pr\u00e8s du <strong>root<\/strong> (emplacement du fuselage).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u2714\ufe0f R\u00f4le :<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Forcent le <strong>d\u00e9crochage de l\u2019aile int\u00e9rieure<\/strong> en premier<\/li>\n\n\n\n<li>Assurent que l\u2019extr\u00e9mit\u00e9 d\u2019aile (qui porte les ailerons) reste en flux plus longtemps<\/li>\n\n\n\n<li>\u00c9vitent les vrilles involontaires<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">C\u2019est un \u00e9l\u00e9ment <strong>de s\u00e9curit\u00e9<\/strong> contre le d\u00e9crochage asym\u00e9trique.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">\u2708\ufe0f 11. R\u00e9sum\u00e9 selon l\u2019\u00e9quipement<\/h1>\n\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>\u00c9quipement<\/th><th>Effet principal<\/th><th>Impact sur le d\u00e9crochage<\/th><\/tr><\/thead><tbody><tr><td><strong>Volets<\/strong><\/td><td>Augmentent portance et tra\u00een\u00e9e<\/td><td>D\u00e9crochage \u00e0 plus basse vitesse, parfois plus marqu\u00e9<\/td><\/tr><tr><td><strong>Becs (slats)<\/strong><\/td><td>Maintiennent le flux \u00e0 forte incidence<\/td><td>D\u00e9crochage tr\u00e8s progressif, excellent contr\u00f4le \u00e0 basse vitesse<\/td><\/tr><tr><td><strong>Fentes (slots)<\/strong><\/td><td>R\u00e9-\u00e9nergisent le flux<\/td><td>D\u00e9crochage progressif, grande stabilit\u00e9<\/td><\/tr><tr><td><strong>Stall strips<\/strong><\/td><td>Contr\u00f4lent la s\u00e9quence de d\u00e9crochage<\/td><td>D\u00e9crochage plus pr\u00e9visible, anti-vrille<\/td><\/tr><tr><td><strong>Aile \u00e0 fl\u00e8che invers\u00e9e \/ washout<\/strong><\/td><td>R\u00e9duit incidence en bout d\u2019aile<\/td><td>Ailerons restent efficaces<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">\u2708\ufe0f 12. D\u00e9gradations ou usages dangereux<\/h1>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Tirer trop fort m\u00eame avec volets = <strong>d\u00e9crochage acc\u00e9l\u00e9r\u00e9<\/strong><\/li>\n\n\n\n<li>Grande dissym\u00e9trie de volets = <strong>roulis violent au d\u00e9crochage<\/strong><\/li>\n\n\n\n<li>Manque de coordination au pied \u2192 <strong>vrille<\/strong><\/li>\n\n\n\n<li>Approche tr\u00e8s stabilis\u00e9e en volets + mauvaise gestion moteur \u2192 <strong>marge r\u00e9duite<\/strong><\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n","protected":false},"excerpt":{"rendered":"<p>\u2708\ufe0f 1. Qu\u2019est-ce qu\u2019un d\u00e9crochage ? Un d\u00e9crochage n\u2019est pas une perte de vitesse, mais une perte d\u2019adh\u00e9rence a\u00e9rodynamique du flux d\u2019air sur le profil de l\u2019aile, lorsque l\u2019angle d\u2019attaque d\u00e9passe une valeur critique (souvent autour de 15\u00b0\u201318\u00b0 selon l\u2019aile). La portance chute brusquement \u2192 l\u2019avion ne peut plus compenser son poids \u2192 il commence \u00e0 descendre. \u2708\ufe0f 2. Que<\/p>\n<p><a class=\"more-link\" href=\"https:\/\/acriv.org\/WP\/%f0%9f%9a%a8le-decrochage\/\">Read More<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-2609","page","type-page","status-publish","hentry"],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/acriv.org\/WP\/wp-json\/wp\/v2\/pages\/2609","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/acriv.org\/WP\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/acriv.org\/WP\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/acriv.org\/WP\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/acriv.org\/WP\/wp-json\/wp\/v2\/comments?post=2609"}],"version-history":[{"count":1,"href":"https:\/\/acriv.org\/WP\/wp-json\/wp\/v2\/pages\/2609\/revisions"}],"predecessor-version":[{"id":2611,"href":"https:\/\/acriv.org\/WP\/wp-json\/wp\/v2\/pages\/2609\/revisions\/2611"}],"wp:attachment":[{"href":"https:\/\/acriv.org\/WP\/wp-json\/wp\/v2\/media?parent=2609"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}