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  • #46
    Gents, I find the repeated references to "unprecedented" acceleration and g-loading interesting.

    Lyon said he is still working on the oxygen concentration issue. The problem , Lyon said, is that the Air Force provides the pilots with more oxygen than they need to help them retain consciousness should a worst-case scenario disaster result. But that is complicated by the fact that unlike any other aircraft , the F-22 flies at higher altitudes and higher levels of acceleration – or “High-G.” “We’re working the balance between catastrophic possibility and day-to-day flying,” Lyon said.
    It seems to me that on this issue, the Air Force and NASA are walking a fine line between providing a credible explanation and disclosing information that would suggest F-22's performance envelop is even more impressive than previously realized.

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    • #47
      AFAIK the F-22 is a 9G airplane. So is the F-16 and F-15. The F-22 might be able to sustain 9G at a higher altitude than the earlier jets, but the human body doesn't care... it's at 9G. 9G has been determined to be the highest practical G load the human body can tolerate. If there was a secret 12G max limit on the F-22, pilots wouldn't use it. It hurts too much.

      Onset rates are pretty much identical. Maybe I'm missing something, but physiologically, I'm not seeing anything new in the F-22.

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      • #48
        Originally posted by Chogy View Post
        AFAIK the F-22 is a 9G airplane. So is the F-16 and F-15. The F-22 might be able to sustain 9G at a higher altitude than the earlier jets, but the human body doesn't care... it's at 9G. 9G has been determined to be the highest practical G load the human body can tolerate. If there was a secret 12G max limit on the F-22, pilots wouldn't use it. It hurts too much.

        Onset rates are pretty much identical. Maybe I'm missing something, but physiologically, I'm not seeing anything new in the F-22.
        And yet both the AF and now NASA has been repeating the line about higher G-loading at higher altitudes. It doesn't jive with what seems to be forward. This makes me think that either the plane's performance parameters are different than stated in public, or that the life support systems and physiology works differently at altitude, or that they are being operated in a different way than previous generation fighters.

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        • #49
          Hmm... the latter is possible.

          or that the life support systems and physiology works differently at altitude
          The differences are not going to be huge, though. 9G at 35,000' is going to have the pilot at a slightly higher cabin altitude, and maybe a smidge more O2 in the mix.

          Unless things have changed, training continues to be far more violent and abusive to the body than recent air combat. In trining, it wasn't unusual to have sustained high-G turning fights that might last a few minutes, something that hasn't happened in combat since Vietnam, and the only reason they happened there was because of the limitations of the weapons, all being stern-aspect with the exception of the AIM-7E.

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          • #50
            Wow, hard to believe.

            AP IMPACT: Air Force experts foresaw problems with F-22 stealth fighter; solutions rejected - The Washington Post

            AP IMPACT: Air Force experts foresaw problems with F-22 stealth fighter; solutions rejected

            KADENA AIR BASE, Japan — Years before F-22 pilots began getting dizzy in the cockpit, before one struggled to breathe as he tried to pull out of a fatal crash, before two more went on television to say the plane was so unsafe they refused to fly it, a small circle of U.S. Air Force experts knew something was wrong with the prized stealth fighter jet.

            Coughing among pilots and fears that contaminants were leaking into their breathing apparatus led the experts to suspect flaws in the oxygen-supply system of the F-22 Raptor, especially in extreme high-altitude conditions in which the $190 million aircraft is without equal. They formed a working group a decade ago to deal with the problem, creating an informal but unique brain trust.
            Internal documents and emails obtained by The Associated Press show they proposed a range of solutions by 2005, including adjustments to the flow of oxygen into pilot’s masks. But that key recommendation was rejected by military officials reluctant to add costs to a program that was already well over budget.

            “This initiative has not been funded,” read the minutes of their final meeting in 2007.

            Minutes of the working group’s meetings, PowerPoint presentations and emails among its members reveal a missed opportunity for the Air Force to improve pilot safety in the 187-plane F-22 fleet before a series of high-profile problems damaged the image of an aircraft that was already being assailed in Congress as too costly. Its production was halted last spring and the aircraft has never been used in combat.

            Among the problems reported after the working group’s warnings:

            — In 2008, pilots began reporting a sharp increase in hypoxia-like problems, forcing the Air Force to finally acknowledge concerns about the F-22’s oxygen supply system.

            — Two years later, the oxygen system contributed to a fatal crash. Though pilot error ultimately was deemed to be the cause, the fleet was grounded for four months in 2011.

            — New restrictions were imposed in May, after two F-22 pilots went on the CBS program “60 Minutes” to express their continued misgivings.

            The Air Force says the F-22 is safe to fly — a dozen of the jets began a six-month deployment to Japan in July — but flight restrictions that remain in place will keep it out of the high-altitude situations where pilots’ breathing is under the most stress.

            One of the working group’s proposed fixes, a backup oxygen system, is expected to be in place by the end of the year. And the Air Force, which blamed the oxygen shortage on a faulty valve in the pilots’ vests, says a fix to that problem is also in the works. The working group also proposed changes in warning systems to alert pilots to system failures and urged enhanced tracking of potential health hazards to pilots and ground crew caused by the materials used to bolster the aircraft’s stealth — two more issues the Air Force investigations would later focus on.

            More broadly, the Air Force now concedes that while its own experts were tackling the F-22’s issues, it was too aggressive in cutting back on life-support programs intended to ensure pilots’ safety. It is now in the process of rebuilding them.

            The F-22’s gradual return to regular flight operations follows an exhaustive investigation over the past year by the Air Force, NASA, experts from Lockheed Martin, which produces the aircraft, and other industry officials.

            But the documents obtained by AP show many of the concerns raised in that investigation had already been outlined by the working group that was formed in 2002, when the fighter was still in its early production and delivery stage.

            It called itself RAW-G, for Raptor Aeromedical Working Group, and brought together dozens of experts in life support, avionics, physiology and systems safety, along with F-22 aircrew and maintainers.

            The group was founded by members of the F-22 community who were concerned about how the unique demands of the aircraft could affect pilots. The fighter can evade radar and fly faster than sound without using afterburners, capabilities unmatched by any other country. It also flies higher than its predecessors and has a self-contained oxygen generation system to protect pilots from chemical or biological attack.

            According to the Air Force, RAW-G was created at the suggestion of Daniel Wyman, then a flight surgeon at Florida’s Tyndall Air Force Base, where the first F-22 squadron was being deployed. Wyman is now a brigadier general and the Air Combat Command surgeon general.

            By the time RAW-G got going, some pilots were already experiencing a problem called “Raptor cough” — fits of chest pain and coughing dating back to 2000 that stem from the collapse of overworked air sacs in the lungs.

            The group concluded that the F-22’s On-Board Oxygen Generation System — or OBOGS — was giving pilots too much oxygen, causing the coughing. The more often and higher the pilots flew after being oxygen-saturated, group members believed, the more vulnerable pilots affected by the condition would be to other physiological incidents.

            RAW-G recommended more tests and that the F-22’s oxygen delivery system be adjusted through a digital controller and a software upgrade.

            “The schedule would provide less oxygen at lower altitudes than the current schedule, which has been known to cause problems with delayed ear blocks and acceleration atelectasis,” the technical term for the condition that leads to the coughing, according to the minutes from RAW-G’s final meeting.

            RAW-G members had spent two years pushing for the change in the oxygen schedule — the amount of oxygen pumped into pilots’ life-support systems — but the necessary software upgrade never came through.

            “The cost was considered prohibitive in light of other items that people wanted funded for the F-22,” said Kevin Divers, a former Air Force physiologist who spearheaded RAW-G until he left the service in 2007 and the group disbanded.

            Divers believes the cost would have been about $100,000 per aircraft.


            The link between oxygen saturation at lower altitudes and the recent spate of hypoxia-like incidents at high altitudes remains a matter of debate, and it is likely that there are other contributing factors. Both the Air Force and the NASA, however, now concur that the F-22’s oxygen schedule needs to be revised.

            At a House subcommittee hearing this month, Clinton Cragg, the chief engineer for NASA’s Engineering and Safety Center, said the current schedules provide too much oxygen at lower altitudes — as RAW-G warned — and also agreed with RAW-G that testing was insufficient “even back to the beginning of the program.”

            Lt. Col. Tadd Sholtis, a spokesman for the Air Combat Command at Virginia’s Langley-Eustis Air Force Base, the home base for the F-22s deployed in Japan, said the RAW-G group was not meant to last indefinitely. He said it was set up to help officials at Tyndall get up to speed on the medical aspects of flying the F-22, and disbanded “after several meetings and a safe transition to regular F-22 operations at Tyndall.”

            But even in the last days of the group, its members were identifying more work that needed to be done. In an email to Divers before RAW-G’s final meeting, Wyman said health hazards for F-22 pilots and ground crew needed more study.

            “I am interested in the potential physiologic/health issues related to flying and fixing the F-22s,” he wrote. He added that increased gravitational forces during accelerated turns, high speeds and high altitudes, noise and the “low observable” materials used to give the aircraft its stealth qualities “might lead to new health issues.”

            By then, the F-22 was just one of the aircraft RAW-G was concerned with. Minutes from the final meeting include “action items” identifying potential issues with the F-35 and the CV-22 Osprey, and a suggestion that RAW-G’s work be carried on with higher-level oversight so that it would have more clout. But after Divers left the service, no one took up the torch.

            The Air Force says it believes improvements now being put into place make the planes safe to fly under limited restrictions. It is now refitting all pilot life support gear, redesigning the vests so that modified versions can be introduced in the fall, and adding the automated backup oxygen system in the cockpit by the end of the year.

            In the meantime, the F-22s in Japan must fly under 44,000 feet so that the flawed vests will not be required, and are on a 30-minute “tether,” meaning they must be within 30 minutes of an emergency landing site.

            “While we cannot eliminate risk from flight operations, we are confident the F-22 is safe now and on a path to being as safe as any other fighter we fly,” Sholtis said.

            The Air Force says there have been no breathing-related incidents in the F-22 fleet since March 8, though the aircraft has marked more than 9,000 sorties, or 12,000 flight hours, since then.

            “We won’t ever bury anything if there are issues, but so far, none,” said Brig. Gen. Matthew Molloy, an F-22 pilot and commander of the 18th Wing on Japan’s Kadena Air Base. “This airplane is absolutely vital to our national security.”

            The F-22’s woes have been especially troubling for the Air Force because it is in many ways its showcase aircraft — and its most controversial. At $190 million apiece, not counting development costs, it was lambasted in Congress as an overpriced luxury item not suited to current conflicts.

            But the flurry of investigations into its safety problems have also revealed a more fundamental issue within the Air Force itself: decades of budget-cutting and outsourcing that severely compromised its expertise on what kinds of physiological problems pilots might face when flying in the extremely demanding conditions posed by its most advanced aircraft.

            “Over the past 20 years, the capabilities and expertise of the USAF to perform the critical function of Human Systems Integration have become insufficient,” Gregory Martin, who led the study into its oxygen problems for the Air Force Scientific Advisory Board investigation that began in 2011, told the House subcommittee.

            Martin said the program’s decline cost the Air Force expertise on life support systems, altitude physiology and pilot health and safety. He said that was compounded by “inadequate research, knowledge, and experience for the unique operating environment of the F-22.”

            Maj. Gen. Charles Lyon, the Air Combat Command’s director of operations, concurred with those conclusions at a news conference last month. “We probably overshot the mark on how much downsizing we did in this study of physiology,” he said.

            Divers considers the demise of RAW-G to be emblematic of that decline.

            “The RAW-G became a brain trust, for sure, and it pushed various things that otherwise would have been completely ignored or not even brought up as an issue,” Divers said. “All of that died in 2007.”
            Last edited by Gun Grape; 28 Sep 12,, 21:07.

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            • #51
              Oh that's going to cause some problems.

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              • #52
                F-22 crashed at Tyndall today. Happened on base near highway 98. Road closed for a while. Road is near the landing approach to the main runway. Plane went down just before the drone runway for those that have been stationed on the base.

                Pilot ejected and reported to be OK.

                Tyndall is where f-22 pilots go to learn how to fly. But according to the AF the pilot was not "Under training"

                On a side note, Back in Sept Tyndall set the record for most F-22 sorties in a day. 53. All pilots were instructors who needed to update their hours before the end of the FY.

                In May a training pilot skidded down the runway on takeoff. Forgot to bring the plane to full mil power and prematurely raised the landing gear.

                UPDATE: F-22 crashes at Tyndall - News - The News Herald
                Last edited by Gun Grape; 16 Nov 12,, 04:53.

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                • #53
                  Stuff happens.

                  Critics, I'm sure, will use this to (again) attack the airplane. However, statistically, the US Air Force is actually ahead of the curve on this one; I think the F-22 is averaging one lost airframe per year, which is WAY below the average for other cutting-edge aircraft. Don't have the statistics handy, but I'm sure other a/c have a worse operational history.
                  "There is never enough time to do or say all the things that we would wish. The thing is to try to do as much as you can in the time that you have. Remember Scrooge, time is short, and suddenly, you're not there any more." -Ghost of Christmas Present, Scrooge

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                  • #54
                    This article says there was another crash in May, is this a fact?
                    Thursday's crash occurred the same day the Air Force reportedly released the results of their investigation into another F-22 crash at Tyndall. The pilot in that crash, which occurred in May, was able to bail out and save himself as well. In its report, the Air Force blamed the May crash on pilot error, according to a report by the Air Force Times.Link

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                    • #55
                      Originally posted by Stitch View Post
                      Stuff happens.

                      Critics, I'm sure, will use this to (again) attack the airplane. However, statistically, the US Air Force is actually ahead of the curve on this one; I think the F-22 is averaging one lost airframe per year, which is WAY below the average for other cutting-edge aircraft. Don't have the statistics handy, but I'm sure other a/c have a worse operational history.
                      Most of those aircraft had enough orders to lose an airframe here and there. At least this was a Tyndall bird, not a combat-coded airframe.

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                      • #56
                        Originally posted by Jimmy View Post
                        Most of those aircraft had enough orders to lose an airframe here and there. At least this was a Tyndall bird, not a combat-coded airframe.
                        Interesting that it's the T&E birds that keep crashing . . . . .
                        "There is never enough time to do or say all the things that we would wish. The thing is to try to do as much as you can in the time that you have. Remember Scrooge, time is short, and suddenly, you're not there any more." -Ghost of Christmas Present, Scrooge

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                        • #57
                          And its being reported that the cause of this crash is the same as the one in May.

                          It was the students 2d flight in the plane. Doing touch and goes, failed to bring the plane up to full mil power and raised the landing gear to soon.

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                          • #58
                            Originally posted by Stitch View Post
                            statistically, the US Air Force is actually ahead of the curve on this one; I think the F-22 is averaging one lost airframe per year, which is WAY below the average for other cutting-edge aircraft. Don't have the statistics handy, but I'm sure other a/c have a worse operational history.
                            Yes but other aircraft were also produced with far larger production runs to fall back on. The US has maybe what 180 F-22 airframes? I don't know the exact figures but MD produced how many F-15's - something like 1300 or so? As for F-18's and F-16'S ???? My point being that the limited number available and the enormous investment each one represents means the loss of a single F-22 is that much more of a problem. As good as they are they each F-22 can only be in one place at a time.
                            If you are emotionally invested in 'believing' something is true you have lost the ability to tell if it is true.

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                            • #59
                              Originally posted by Stitch View Post
                              Interesting that it's the T&E birds that keep crashing . . . . .
                              And Alaska.

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                              • #60
                                Originally posted by Jimmy View Post
                                And Alaska.
                                Sorry Jimmy, are you saying the Alaska one was a T&E as well or was it coded?

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