F-22 Raptor

Rappel du premier message :

Dans ce qui suit, des extrait d'un certain nombre d'article sur le web parlant de cette terreur volant, je vous laisse admirer d'abord le charme de cette bête de combat.

Citation :

Citation :

F-22 Oxygen Problem Still Eluding Investigators
http://www.military.com/news/article/f22-oxygen-problem-still-eluding-investigators.html

Citation :

F-22 scientific board findings announced




Air Force leaders provided an update on the Air Force Scientific Advisory Board study into the F-22 Raptor life support systems and flight operations during a briefing in the Pentagon March 29.

Retired Gen. Gregory Martin, an aviator and a former commander of two major commands, chaired the nine member SAB team which studied the aircrafts' on-board oxygen generation systems and briefed its findings and recommendations in trying to determine a root cause for pilots experiencing unexplained physiological events with the F-22 Raptor.

"From April 2008 until May 2011, the Air Force experienced 14 physiological incidents with the fleet of F-22s," Martin said. "Each incident was investigated, and of those incidents, 10 did not reveal a root cause."

It was the unexplained nature of those incidents that gave the Air Force concern and led the Secretary of the Air Force to ask for a broad area review which the SAB conducted, he added.

"We were unable to determine a root cause, but we were able to put in place the proper safety measures and risk mitigation techniques that would allow the F-22 fleet to return to fly...to ensure the integrity of the life support system," Martin said. "We went from ground test to flight test to a return to fly phase, and moving into a transition phase."

The advisory board made nine findings and 14 recommendations based on a seven-month study of the F-22's evolution - from conception and acquisition through current flight operations - which the Air Force can use to move forward.

Martin said the findings and recommendations fall into three main areas; the acquisition processes and policies, the organizational structure recommendations and equipment recommendations to not only protect the pilots and crew members today but also for the future.

"Some of the things we recommended give us a much better understating of the pilots' performance in those environments that we have not operated in before," Martin said. "It will further our understanding of the aviation physiology of operating in that environment."

Air Force leaders remain steadfast that the F-22 is a fully combat capable aircraft and they have every confidence in its current and future performance.

"Since September of last year we've flown over 10,000 sorties," said Maj. Gen. Charles Lyon, Air Combat Command Director of Operations. "We've had a 99.9 percent effective flying rate relative to physiological incidents, but that is not good enough. We will not rest; we will not stop; we will not end this journey we are on until we carry that 99 percent decimal point to the farthest right that we can."

The Air Force is well into the implementation phase of the recommendations from the SAB team and continues to aggressively pursue the root cause of these unexplained incidents, he said.

"Let there be no doubt that safety is paramount to the men and women who operate (the F-22) and the commander's who command them," Lyon said. "When we wear this uniform there is risk, there is risk inherent in aviation and risk inherently in conducting military operations.

Pilot safety has and always will remain a priority for ACC, Lyon added.

"We have taken a 9-1-1 call approach" Lyon said. "We have instructed and talked to our members in the field; whenever you get any indication that something may not be right, knock it off, the flying equivalent of calling 9-1-1 and terminate the flight. All eyes are focused on you and the safe recovery of your aircraft."

When a physiological event occurs, the pilot is met by a medical team to care for the pilot and take additional tests and send the tests to the lab, and so far nothing remarkable has come back from the lab tests we've analyzed, he said.

"When it comes to safety, no one second guesses the pilot," Lyon said.

The F-22 is a fifth generation fighter and one that is needed for the United States to establish air superiority in today's and tomorrow's conflict's, said Maj. Gen. Noel "Tom" Jones, Air Force Deputy Chief of Staff for Operations, Plans and Requirements.

"This aircraft is the world's most advanced aircraft and does air superiority mission unlike any other aircraft in the world," Jones said. "This is the leading edge of technology, and if our nation needs a capability to enter contested airspace to deal with air forces that are trying to deny our forces the ability to maneuver without prejudice on the ground; it will be the F-22 that takes on that mission."

http://www.defencetalk.com/f-22-scientific-board-findings-announced-41332/

F-22 au red flag 2012

reacteur du f-22

Citation :

le 195ème et dernier F22 Raptor vient d'être livré à l'US air force.
La fin de la fabrication en série du chasseur le plus évolué, le chef de file inconditionnel de la nouvelle 5ème génération marque la fin d'un chapitre dans un programme hautement controversé.

La construction de ce chasseur de supériorité aérienne devait répondre à des critères très strictes. Il fallait redonner les moyens aux aviateurs d'assurer sans concurrence une domination aérienne totale, grignotée à l'époque par l'appartition du Sukhoi 27, formidable chasseur venant de l'URSS et faisant de l'ombre au F15 Eagle.

Pour ce faire, la nouvelle monture des pilotes de l'USAF devait pouvoir voler très haut, être capable de fendre l'air à plus de Mach1,5 sans faire usage de post-combustion (la super-croisère) et être furtif. En bref, un chasseur capable de voler plus vite, plus haut et à même de voir sans être vu.

Lors du lancement du programme, et après que le YF22 de lockheed fut choisi en 1992 en lieu et place du YF23 de Northrop, la cible de 750 appareils envisagée au départ fut réduite à 648 avions en raison des surcoûts entraînés par les 5 années de retard pris par le programme. La fin de la guerre froide a vu la menace de l'est se dissiper et ce chasseur à la supériorité inégalée devenait une dépense de plus en plus difficile à justifier. La cible des intentions d'achat fut à nouveau réduite à 339 avions en 1997 et encore à 295 en 2001 et 277 en 2003. En 2007, l'administration Obama décida d’arrêter la production de ce chasseur de tous les superlatifs à 183 exemplaires de série. Le coût total du programme (développement et production) est estimé à 62 milliards de dollars.

Malgré les belles paroles prononcées par les officiels lors de la cérémonie de remise à l'US air force de ce dernier avion neuf, plusieurs ombres sont à rajouter au tableau. L'avion présente encore beaucoup de problèmes de jeunesses à même de mettre en doute la capacité de ce chasseur à être réellement opérationnel.

La première et non des moindres concerne le problème de génération d'oxygène embarqué. Rien n'a officiellement fuité, mais le système perd en efficacité lorsque l'avion monte en altitude. Si le plafond opérationnel est limité, l'avantage tactique aussi. Quand ce n'est tout simplement pas les pilotes qui décident de ne plus monter à bord...
Des problèmes de corrosion sont aussi apparus. L'absence de liaison 16 rends le chasseur difficilement intégrable dans une force coalisée, ce qui fait que le chasseur ne fut jamais déployé en opérations bien qu'il fut déclaré opérationnel en 2005.

On le voit, tout n'est pas rose pour ce programme qui est loin d'être terminé. Gageons que lockheed Martins et l'USAF sauront surmonter tous ces problèmes de concert afin d'offrir aux USA ce chasseur à la supériorité aérienne chèrement acquise.

http://portail-aviation.blogspot.fr/2012/05/usaf-le-dernier-raptor-livre.html

nouvelle images HD du f-22

Big problem with F22

regardez 60 minutes d'hier sur CBS

info déjà relaté ici il y a 6 jours. (je ne suis pas mécontent de moi, héhé )

http://portail-aviation.blogspot.fr/2012/05/usaf-des-pilotes-evitent-le-f22.html

ça craint ,normalement tout pilote reverai de piloter cette belle mécanique..........
Et en plus Lookeed se voit attribuer 24 millions de dollars pour remedier a ce probleme..........

Y'a pas de problème, on peut piloter cet engin de rêve; mais en apnée XD

c´est a cause du systeme OBOGS sohphistiqué,s´ils auraient pris celui des teen serie ca n´aurait pas fait tant de probleme a mon avis

Je comprendrai jamais ce fait de vouloir innover alors qu'un systémes existe déjà et qu'il ne pose pas de problémes.

Un systeme de generationd'oxygene c'est autant de bouteillies en moins, donc de masse et de volume gagné. Ca existe sur d'autres avions comme le rafale et ca ne pose pasplus de problemes que ca

Ca je l'ai bien compris mais pourquoi investir si ce que l'ont a déjà est fiable..........
Ou alors cela ne faisait pas assez bien pour le Raptor d'avoir un systemes plus agée........

le raptor a plusieurs particularités que n'ont pas les autres avions. Premièrement son plafond opérationnel est au moins 30% plus élevé que tous les autres chasseurs. De plus, à cause de la recherche d'une furtivité maximum, tout ce qui est prélèvement ou rejet d'air doit se faire de manière la plus discrète possible. Donc doit y avoir des répercutions sur ce qu'on peu ou pas faire.

les système de génération d'oxygènes sont relativement récents. Chez les US, les F15 ou F16 par exemple n'en ont pas. Faut que je vérifie pour le super hornet, mais le F22 est un des tout premier chasseur à en avoir un. Après, te dire pourquoi chez les US ça déconne et pas chez nous... Je n'irais pas jusqu'à dire qu'on est meilleur

bubzy a écrit:

Chez les US, les F15 ou F16 par exemple n'en ont pas

si les F16 ont l´OBOGS

Effectivement, mais pas d'origine.

C'est la société Cobham qui les fabrique et leurs systèmes sont installés sur les Harrier T-45, F-14D,
F/A-18, F-15E, A-10, A-4AR, AL-X, GR5, T-4,
T-6A, T-50, F-5, F-2, C-130 and PC-9

Une des hypotheses pour les prblemes que rencontre les pilotes du f22, serait un probleme de polution provenant du revetement unique de l avion.

http://translate.googleusercontent.com/translate_c?rurl=translate.google.com&sl=auto&tl=fr&u=http://www.defesabr.com/blog/index.php/28/05/2012/furtividade-e-falta-de-ar-dos-pilotos-do-f-22-raptor/&usg=ALkJrhjZqAzc8iJVCaIbRrkbMcLflYGn9wmm

charly a écrit:

Une des hypotheses pour les prblemes que rencontre les pilotes du f22, serait un probleme de polution provenant du revetement unique de l avion.

http://translate.googleusercontent.com/translate_c?rurl=translate.google.com&sl=auto&tl=fr&u=http://www.defesabr.com/blog/index.php/28/05/2012/furtividade-e-falta-de-ar-dos-pilotos-do-f-22-raptor/&usg=ALkJrhjZqAzc8iJVCaIbRrkbMcLflYGn9wmm

wow puis-je m'aventurer a dire que le revetement serait base sur des nanotechnologies? sachant qu'il s'agit de structure tres toxiques et mal etudies

http://www.ynetnews.com/articles/0,7340,L-3919257,00.html

Citation :

Israel's secret new weapon?
Israeli company uses nanotechnology to develop paint that makes planes disappear off radar

Ofer Petersburg
Published: 07.13.10

Citation :

Combat Edge anti-g ensemble might be causing Raptor’s oxygen woes

The Combat Edge upper pressure-garment worn by US Air Force pilots flying the Lockheed Martin F-22 Raptor might be the cause of the fifth-generation fighter's oxygen maladies, sources say.

While pilots need counter-pressure from the vest-like pressure garment to exhale at low cabin pressures found in the Raptor's cockpit, the Combat Edge and associated breathing systems might be providing too much pressure especially under g-loading.

"It just seems a little weird to breathe of off this thing," one source says. "Because you can't expand your lungs as easily because you have something restricting you."

©Lockheed Martin

The extra load imposed on the pilots by the added pressure under g-forces could be causing them to "over-breathe the system".

A compounding factor may be a condition known as acceleration atelectasis. The condition causes the pilot's lungs to have trouble bringing oxygen to the blood system because pure oxygen--93% oxygen in the Raptor's case-- and high gravity loads set up the pilots for a condition where the air sacs in the lungs suffer partial collapse.

The result of acceleration atelectasis is the so called "Raptor cough"-where F-22 pilots have a pronounced cough as the pilot's body attempts to re-inflate the sacs under normal atmospheric pressure on the ground.

Earlier tests would not have caught the problem because the breather device used to test the Combat Edge system does not compensate for pilot's lungs being unable to expand as readily. The breather device always draws the same volume of air.

A lack of ability to test for restricted expansion kept the condition from being seen as a problem. The restricted breathing could lead to hyperventilation symptoms or even bigger issues if the pilot is suffering from acceleration atelectasis.

However, the source says, the pressure-garment problem has been a known concern since at least 2000 when a similar garment provided by Boeing was being flown. But at that time, the USAF did not believe that the extra pressure was a serious concern. Now however, the USAF is starting to believe that the Combat Edge is behind the Raptor's woes. But while current USAF research is pointing to the Combat Edge as the primary culprit behind the F-22's maladies, the source says that it is probably only part of the problem.

Unlike U-2 pilots, who fly only after a several-day rest period after each flight, F-22 pilots will sometimes fly more than once a day. This means that the pilots are flying before they fully recover from the effects of acceleration atelectasis. Thus when they are g-loading in flight, they are further exposed to the pressure from the Combat Edge and their breathing device. The exposure to maximum oxygen while already suffering from acceleration atelectasis means even less oxygen saturation for the pilot. The sum total can result in the "hypoxia-like" physiological symptoms that have been vexing F-22 pilots for the past year.

"It was an annoyance issue, but an annoyance issue after you were on the ground," the source says. "But there is no exposure limit on these guys and early on a double turn was a rarity."

Ironically, some of the safety measures that the USAF added after the service lifted the grounding such as flying with a negative-pressure carbon-filter--which is having oxygen pushed through it under pressure-- and with the oxygen system set on maximum at all times probably exacerbated the problem, the source says.

One possible solution might be the new pressure-garment designed for the Lockheed Martin F-35, which could potentially solve the some of the pressure issues. But F-22 crews may need to take a 24h break between flights, the source says. That would cause a sortie generation problem, however.

Officially, the USAF maintains that it has yet to find the root cause of the oxygen-system problem. "Our risk mitigation and data collection are evolving based on our experience and [Secretary of Defense] guidance. Analysis of the data is getting us closer to identifying a root cause or causes, although we don't have preliminary results or a projected completion date to share at this time," the USAF says.

Meanwhile, pilots flying the F-22 have not suffered any new unexplained hypoxia-like physiological incidents in nearly three months, the service says.

"We haven't had an unexplained physiological incident since 8 March," the USAF says.

flightglobal