\tLe Pentagone a d\u00e9cid\u00e9 que sa flotte de F-35, d\u00e9signation s\u00e9rieuse du JSF, \u00e9tait \u00e0 nouveau autoris\u00e9e \u00e0 \u00e9voluer dans son \u00e9l\u00e9ment, on veut dire : voler, apr\u00e8s l’interruption<\/a> due \u00e0 la d\u00e9couverte d’une fissure dans une ailette de la turbine d’un r\u00e9acteur Pratt & Whitney F135 install\u00e9 sur cet avion. Danger Room<\/em> annonce la chose le 3 mars 2013<\/a>, r\u00e9percutant les d\u00e9clarations rassurantes de Pratt & Whitney, ce que Danger Room<\/em> d\u00e9signe comme \u00abthe best possible spin<\/em>\u00bb dont le sens est pour le moins ambigu. On comprend plus loin pourquoi.<\/p>\n<\/p>\n \t\u00abPratt and Whitney put the best possible spin on the turbine blade’s potentially catastrophic flaw, which if undetected could have caused a crash. Prolonged exposure to high levels of heat and other operational stressors on this specific engine were determined to be the cause of the crack, the company announced late Thursday. No additional cracks or signs of similar engine stress were found during inspections of the remaining F135 inventory. No engine redesign is required as a result of this event.<\/em>\u00bb<\/p>\n<\/p>\n \tLe JSF est une cha\u00eene sans fin de petites, moyennes et grosses catastrophes qui ne cessent de r\u00e9percuter leurs effets les unes sur les autres, pour former la catastrophe monstrueuse qu’on conna\u00eet. Ici, bien entendu, nous ne parlons que du moteur, qui est, pour le public que nous sommes, un nouveau domaine catastrophique du JSF, qui en a d\u00e9j\u00e0 beaucoup \u00e0 son actif.<\/p>\n<\/p>\n \tOriginellement, le F135, moteur \u00e0 la pouss\u00e9e \u00e9norme de 40.000 livres, correspondait bien au JSF th\u00e9orique et triomphant, envisag\u00e9 comme un avion aux lignes a\u00e9rodynamiques assez pures et au poids correspondant bien au moteur. Puis, le tr\u00e8s long d\u00e9veloppement de la chose ayant commenc\u00e9, l’avion commen\u00e7a parall\u00e8lement \u00e0 rencontrer ses diverses catastrophes. Cela obligea \u00e0 diverses refontes qui ne cess\u00e8rent d’alourdir l’avion lui-m\u00eame, autant que l’a\u00e9rodynamisme de sa silhouette, transformant l’agile merveille en un embarrassant fer \u00e0 repasser.<\/p>\n<\/p>\n \tCette situation impliquait que, pour tenir ses performances de vol promises, et m\u00eame avec l’intervention amicale de l’USAF qui abaissa un tantinet ses exigences op\u00e9rationnelles, le F135 devait, et doit, et devra de plus en plus fonctionner \u00e0 tr\u00e8s haut r\u00e9gime et ainsi produire une tr\u00e8s haute chaleur tr\u00e8s dommageable \u00e0 lui-m\u00eame. Des syst\u00e8me nouveaux pouvant supprimer ce handicap structurel et sans fin sont en d\u00e9veloppement, mais, semble-t-il, beaucoup trop cher et trop avanc\u00e9 pour aller sur le F-35\/F135. Ainsi, conclut Danger Room<\/em>, le JSF est-il condamn\u00e9 \u00e0 voler ad vitam aeternam<\/em> avec l’\u00e9p\u00e9e de Damocl\u00e8s de la probabilit\u00e9, sinon de la certitude d’interruptions de vol successives et intempestives, avec son moteur qui chauffe trop et ses turbines ainsi fragilis\u00e9es. Encore s’agit-il de l’hypoth\u00e8se optimiste et ne dit-on rien de ce qu’il pourrait advenir du moteur \u00e0 mesure qu’il avance dans l’usage op\u00e9rationnel dans de telles conditions, c’est-\u00e0-dire avec la possibilit\u00e9 d’un point de rupture catastrophique ou de nouvelles faiblesses r\u00e9sultant d’un tel fonctionnement (Mais tout cela est vraiment<\/strong> optimiste, puisque cela suppose que le JSF entrera un jour en service.)<\/p>\n<\/p>\n \t\u00abBut the redesign has an adverse effect on the plane’s aerodynamics, making the F135 work harder than is normal for a fighter engine. Generating more than 40,000 pounds of thrust, the F135 is the most powerful fighter motor ever. Even though the Pentagon has downgraded the F-35’s acceleration specs to ease the strain on the engine, the F135 runs extra hot a problem that has concerned Lockheed and Pratt and Whitney engineers for at least seven years and likely contributed to turbine problems in 2007, 2008 and 2009.<\/em><\/p>\n<\/p>\n \t\u00bbThrough an initiative called Advent, the Air Force and several aerospace companies are investigating a host of new engine technologies that could someday be installed in the F-35, potentially alleviating some of the engine problems. According to the Air Force, Advent’s advancements include turbine section for increased thrust, third stream cooled cooling air for engine hot section thermal management system, and lightweight high temperature materials. General Electric, Pratt and Whitney’s main rival, completed some major testing of Advent tech late last month. Trials of a complete Advent engine are slated for 2017. The Pentagon has said the new motor must be scaled to fit the F-35. But Larry Burns, government program manager for Advent, said it’s unlikely the full Advent motor will be installed on the F-35. Owing to the high cost, such retrofit are few and far between, Burns told reporter Steve Trimble.<\/em><\/p>\n<\/p>\n \t\u00bbSo the Pentagon’s mainstay future fighter is probably stuck with its existing engine, as well as with that motor’s high temperatures and fragile turbines. And that means groundings like last week’s could be a distressingly common occurrence.<\/em>\u00bb<\/p>\n<\/p>\n \n dedefensa.org<\/em><\/p><\/p>\n","protected":false},"excerpt":{"rendered":" JSF r\u00e9par\u00e9 mais irr\u00e9parable Le Pentagone a d\u00e9cid\u00e9 que sa flotte de F-35, d\u00e9signation s\u00e9rieuse du JSF, \u00e9tait \u00e0 nouveau autoris\u00e9e \u00e0 \u00e9voluer dans son \u00e9l\u00e9ment, on veut dire : voler, apr\u00e8s l’interruption due \u00e0 la d\u00e9couverte d’une fissure dans une ailette de la turbine d’un r\u00e9acteur Pratt & Whitney F135 install\u00e9 sur cet avion.… <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"","neve_meta_content_width":0,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":"","_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[14],"tags":[11988,4718,2969,7409,5339,8590,11987],"class_list":["post-74873","post","type-post","status-publish","format-standard","hentry","category-ouverture-libre","tag-ailette","tag-danger","tag-f-35","tag-f135","tag-moteur","tag-room","tag-turbine"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/new.dedefensa.org\/index.php\/wp-json\/wp\/v2\/posts\/74873","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/new.dedefensa.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/new.dedefensa.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/new.dedefensa.org\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/new.dedefensa.org\/index.php\/wp-json\/wp\/v2\/comments?post=74873"}],"version-history":[{"count":0,"href":"https:\/\/new.dedefensa.org\/index.php\/wp-json\/wp\/v2\/posts\/74873\/revisions"}],"wp:attachment":[{"href":"https:\/\/new.dedefensa.org\/index.php\/wp-json\/wp\/v2\/media?parent=74873"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/new.dedefensa.org\/index.php\/wp-json\/wp\/v2\/categories?post=74873"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/new.dedefensa.org\/index.php\/wp-json\/wp\/v2\/tags?post=74873"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}