What's the latest on tilt rotors?
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MV-22 Osprey Soon to Try it Again
Part 1/2
Crucial test
By BOB COX
Star-Telegram Staff Writer
May. 27, 2002
When the V-22 Osprey lifts off again Wednesday for a crucial round of flight tests, Bell Helicopter Textron and Boeing Co. officials hope to show that they have fixed myriad mechanical flaws that contributed to a December 2000 crash and the aircraft's grounding. But there is a bigger question that the manufacturers, the Marines and the Pentagon must answer in the coming months about the V-22.Can the revolutionary tilt-rotor, which takes off like a helicopter and flies like an airplane, perform hard combat maneuvers without going into a deadly roll? A series of reports presented to Pentagon officials last year suggests that the V-22, when flown like a helicopter, possesses unforeseen characteristics that can cause it to lose lift on one side and go into a roll. Close to the ground, that would probably cause a crash. Concerns about unusual aerodynamic problems have haunted the Osprey since April 2000, when a V-22 suddenly rolled out of control and crashed into the desert at Marana, Ariz., killing all 19 Marines aboard. The Marines blamed the accident on pilot errors that caused the aircraft to undergo a turbulent condition called vortex ring state. A top Marine general dismissed the accident as "nothing new ... that we haven't seen in helicopters." But tests performed for several months afterward showed that there appears to be something different about the V-22.
Seven times during 21 high-altitude test flights at the Navy's Patuxent River air base, a V-22 suddenly began to roll when it was flown like the craft involved in the Arizona crash. "There were some long faces on Marine officers at the Pentagon the first time that happened," says Philip Coyle, the former head of the Pentagon's weapons testing office who has frequently raised questions about the V-22. "It got everybody's attention." In one case, a V-22 reached an 84-degree bank, its wings nearly perpendicular to the ground, according to a Bell/Boeing presentation to the Pentagon's "Blue Ribbon Panel," which investigated the aircraft after the 2000 accidents. A Pentagon source familiar with the V-22 testing says the aircraft lost 2,000 feet of altitude before the pilots regained control - a margin for error that probably would not exist in a military operation. "There is a flight characteristic here that doesn't exist in a helicopter," says J. Gordon Leishman, an aerospace engineering professor and helicopter aerodynamics expert at the University of Maryland who has studied tilt-rotor aircraft. Officials with Bell dispute that conclusion. They say the V-22 is safe when flown within its prescribed limits. The V-22's chief test pilot, Boeing's Tom MacDonald, acknowledges that valid questions about the aircraft remain to be answered. But MacDonald, who will be at the controls often during the upcoming flight tests, says he's confident that the V-22 will be proved safe and effective.
"There's no doubt in my mind," McDonald says. "None whatsoever. We're going to go out and and fly that aircraft as aggressively as we can and as aggressively as we think other pilots will do it." Flight tests were expected to begin in April and were delayed a second time in early May. The Marines announced Friday the first flight in 18 months will take place Wednesday. The tests, which will be conducted at the Patuxent Naval Air Station in southern Maryland, could last two years. A lot is riding on the flight tests for Fort Worth-based Bell, which employs nearly 5,800 workers in the area and about 250 in Amarillo. Bell officials long ago bet the company's future on the tilt-rotor technology of the V-22. They had even laid plans for a civilian version, though development of that aircraft has been drastically scaled back until the verdict is in on the V-22.
Pentagon officials have indicated that the new testing amounts to a last chance for the V-22. They have said that if problems persist, the program will be killed. The two crashes, eight months apart, led to a flurry of investigations and reviews of the V-22 program. Two Pentagon-appointed panels endorsed the Osprey last year, saying it had no fundamental safety problems. But both called for much more extensive flight tests. The `Star-Telegram,' in consultation with outside experts, reviewed many of the technical reports made to both the Blue Ribbon Panel and a review panel headed by a top NASA official. Officials with Bell Helicopter declined to discuss the reports in detail.
Although final reports by the two review panels touched on some of the issues, none were highlighted as major concerns. Others were dismissed. The panel headed by Henry McDonald, administrator of the NASA space agency's Ames Research Center in California, concluded in its public report that "there are no known aeromechanics phenomena that would stop the safe and orderly development and deployment of the V-22." Some helicopter experts have been sharply critical of that conclusion. "The McDonald report looks to me like a whitewash," said Dave Jenney, the retired chief engineer for Bell competitor Sikorsky Aircraft Co. "It glosses over some things" that are crucial for a military airplane, he adds. McDonald declined to discuss the panel findings for this article. "He feels it's a thorough and complete report," NASA spokeswoman Ann Hutchinson says. The studies failed to convince some top Pentagon officials of the V-22's safety. As recently as May 2, Defense Undersecretary E.C. "Pete" Aldridge, the government's chief weapons buyer, said he remained skeptical about the tilt-rotor's safety and reliability. "We have not done a lot of the tests of the V-22 in combat maneuvering," Aldridge said in a meeting with reporters. "We don't have many friends up there in the Pentagon," admits MacDonald, the Boeing test pilot, who has acted as a spokesman for Bell and Boeing on the upcoming flight test program.
Crucial test
By BOB COX
Star-Telegram Staff Writer
May. 27, 2002
When the V-22 Osprey lifts off again Wednesday for a crucial round of flight tests, Bell Helicopter Textron and Boeing Co. officials hope to show that they have fixed myriad mechanical flaws that contributed to a December 2000 crash and the aircraft's grounding. But there is a bigger question that the manufacturers, the Marines and the Pentagon must answer in the coming months about the V-22.Can the revolutionary tilt-rotor, which takes off like a helicopter and flies like an airplane, perform hard combat maneuvers without going into a deadly roll? A series of reports presented to Pentagon officials last year suggests that the V-22, when flown like a helicopter, possesses unforeseen characteristics that can cause it to lose lift on one side and go into a roll. Close to the ground, that would probably cause a crash. Concerns about unusual aerodynamic problems have haunted the Osprey since April 2000, when a V-22 suddenly rolled out of control and crashed into the desert at Marana, Ariz., killing all 19 Marines aboard. The Marines blamed the accident on pilot errors that caused the aircraft to undergo a turbulent condition called vortex ring state. A top Marine general dismissed the accident as "nothing new ... that we haven't seen in helicopters." But tests performed for several months afterward showed that there appears to be something different about the V-22.
Seven times during 21 high-altitude test flights at the Navy's Patuxent River air base, a V-22 suddenly began to roll when it was flown like the craft involved in the Arizona crash. "There were some long faces on Marine officers at the Pentagon the first time that happened," says Philip Coyle, the former head of the Pentagon's weapons testing office who has frequently raised questions about the V-22. "It got everybody's attention." In one case, a V-22 reached an 84-degree bank, its wings nearly perpendicular to the ground, according to a Bell/Boeing presentation to the Pentagon's "Blue Ribbon Panel," which investigated the aircraft after the 2000 accidents. A Pentagon source familiar with the V-22 testing says the aircraft lost 2,000 feet of altitude before the pilots regained control - a margin for error that probably would not exist in a military operation. "There is a flight characteristic here that doesn't exist in a helicopter," says J. Gordon Leishman, an aerospace engineering professor and helicopter aerodynamics expert at the University of Maryland who has studied tilt-rotor aircraft. Officials with Bell dispute that conclusion. They say the V-22 is safe when flown within its prescribed limits. The V-22's chief test pilot, Boeing's Tom MacDonald, acknowledges that valid questions about the aircraft remain to be answered. But MacDonald, who will be at the controls often during the upcoming flight tests, says he's confident that the V-22 will be proved safe and effective.
"There's no doubt in my mind," McDonald says. "None whatsoever. We're going to go out and and fly that aircraft as aggressively as we can and as aggressively as we think other pilots will do it." Flight tests were expected to begin in April and were delayed a second time in early May. The Marines announced Friday the first flight in 18 months will take place Wednesday. The tests, which will be conducted at the Patuxent Naval Air Station in southern Maryland, could last two years. A lot is riding on the flight tests for Fort Worth-based Bell, which employs nearly 5,800 workers in the area and about 250 in Amarillo. Bell officials long ago bet the company's future on the tilt-rotor technology of the V-22. They had even laid plans for a civilian version, though development of that aircraft has been drastically scaled back until the verdict is in on the V-22.
Pentagon officials have indicated that the new testing amounts to a last chance for the V-22. They have said that if problems persist, the program will be killed. The two crashes, eight months apart, led to a flurry of investigations and reviews of the V-22 program. Two Pentagon-appointed panels endorsed the Osprey last year, saying it had no fundamental safety problems. But both called for much more extensive flight tests. The `Star-Telegram,' in consultation with outside experts, reviewed many of the technical reports made to both the Blue Ribbon Panel and a review panel headed by a top NASA official. Officials with Bell Helicopter declined to discuss the reports in detail.
Although final reports by the two review panels touched on some of the issues, none were highlighted as major concerns. Others were dismissed. The panel headed by Henry McDonald, administrator of the NASA space agency's Ames Research Center in California, concluded in its public report that "there are no known aeromechanics phenomena that would stop the safe and orderly development and deployment of the V-22." Some helicopter experts have been sharply critical of that conclusion. "The McDonald report looks to me like a whitewash," said Dave Jenney, the retired chief engineer for Bell competitor Sikorsky Aircraft Co. "It glosses over some things" that are crucial for a military airplane, he adds. McDonald declined to discuss the panel findings for this article. "He feels it's a thorough and complete report," NASA spokeswoman Ann Hutchinson says. The studies failed to convince some top Pentagon officials of the V-22's safety. As recently as May 2, Defense Undersecretary E.C. "Pete" Aldridge, the government's chief weapons buyer, said he remained skeptical about the tilt-rotor's safety and reliability. "We have not done a lot of the tests of the V-22 in combat maneuvering," Aldridge said in a meeting with reporters. "We don't have many friends up there in the Pentagon," admits MacDonald, the Boeing test pilot, who has acted as a spokesman for Bell and Boeing on the upcoming flight test program.
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Part 2 / 2
Much of the debate about the safety of the V-22 stems from the Arizona crash. What happened that April night shocked helicopter experts. The pilots were trying to land when the V-22, which was about 300 feet off the ground, rolled over on its back and plunged into the ground. The Marines' investigation of the crash quickly concluded that the pilots allowed the V-22 to descend too quickly with too little airspeed. As a result, the plane got caught in its own rotor wake, a condition called vortex ring state that causes a rotor to lose lift or to stall. The phenomenon has been blamed for helicopter accidents only rarely and previously received little scientific attention. The official crash report concluded that probably just one rotor underwent vortex ring state and stalled. Within a couple of seconds, that caused the plane to go into the roll, and the pilots had no chance to recover.
It had never occurred to anyone that just one rotor might stall and cause the V-22 to roll. "It's something was that was not on our radar screen at all," said MacDonald, the flight test pilot. (The Marines' handling of the crash investigation is the subject of an inquiry by the Pentagon's inspector general, after a Marine officer alleged improper actions by other officers. A Marine spokesman says the allegations do not affect the conclusion about the cause of the crash.)
In the months after the crash, Bell and Boeing began the special flight tests at Pax River to explore the vortex ring state. That testing was only partially complete when all V-22s were grounded after the December 2000 crash. Bell and Boeing, in their reports to the review panels, say the tests show that the V-22 can recover from a roll if the pilot simply rolls the engines forward to gain speed. But that can take seconds and hundreds of feet of altitude - time and space that even MacDonald concedes may not be available. "If you're close to the ground, it's a bad thing," the Boeing pilot says.
Based on the limited flight testing, the Marines and Bell/Boeing insist that the vortex ring state will not be a problem if the V-22 is flown within the prescribed limits. The V-22 flight manual says pilots should descend no faster than 800 feet per minute when flying at speeds of 40 knots or less - a slow, gradual descent not unlike that of a commercial airliner. MacDonald agrees with that guideline, although he says much more flight testing is needed.
"We're going to do a whole lot more of that when we get back to flying," he said. But the experts who've raised concerns about the V-22 say other test data presented in reports to the review panels strongly indicates that controlling the rate of descent does not eliminate the vortex ring state.
Flight simulator tests show that even with much slower descent, trying to maneuver a V-22 abruptly - making a hard turn or a sudden pull-up to abort a landing - could cause it to roll. Evidence of this was included in a special presentation that NASA's McDonald made to Aldridge in August. That presentation, which has not been made public but was obtained by the `Star-Telegram,' shows that in a simulator test the boundary between safe flight and vortex ring state all but disappears when a maneuver is attempted. Still other simulator tests show that when a pilot attempts an abrupt maneuver, the V-22 may spin out of control in as little as two or three seconds.
That's not much of a margin for error, says Coyle, whose office presented the data to the Blue Ribbon Panel. "A point we made ... was when a pilot is doing a quick stop maneuver, a pull-up, it's because something else is going on," Coyle says. "He's being shot at or he's trying to rescue someone. He's concentrating. If in the midst of that concentration something else occurs, he may not be able to react." In the Arizona accident, the pilot flying the V-22 did not lose control until he tried to turn the airplane to stay in formation.
Boeing's MacDonald concedes that, in theory at least, maneuvers could narrow the safety margin. "We're not sure," he says. "We don't believe it's significant. But we're going to test the hell out of that." When shown the charts that suggest that hard maneuvers could cause the V-22 to stall and roll, several retired Bell test pilots and engineers who worked on the V-22 said the aircraft was not designed for hard maneuvers and should not be flown that way. But Grady Wilson, a combat veteran of the Vietnam War and a former V-22 test pilot for Boeing, said that telling an Osprey pilot he can't maneuver in the heat of battle or even the chaos of military operations is unrealistic.
Wilson agrees that the V-22's maneuverability needs to be thoroughly tested. "As I flew it, we babied it. You had to be really gentle with it." Leishman, the Maryland professor, used a computer to simulate what happens with the rotors of helicopters and an aircraft like the V-22. His findings, in a paper recently published by the American Helicopter Society, show that a tilt-rotor aircraft has more complex aerodynamics than a helicopter. During rapid descent or maneuvers, he believes, it's typical for one rotor to get caught in the other's wake. When that happens the two rotors produce widely varying amounts of thrust.
"The thrust fluctuations lead to the roll response" long before the aircraft should reach vortex ring state, says Leishman, who briefed the NASA panel on his research. Leishman, Coyle and others say the V-22's problems may be related to something less exotic than vortex ring state: a propensity for the rotors to stall easily because they cannot generate enough extra thrust at critical moments to maneuver the airplane. Bell and Boeing engineers, in a written response provided to the `Star-Telegram,' denied that the V-22 is more prone to stall than helicopters. MacDonald says the V-22 will be capable of combat maneuvers. "We do expect people to be under duress in the operational world," he says, "and the aircraft has to be forgiving" of pilot mistakes. "The penalty for a good faith violation of a boundary can't be the loss of an aircraft and the crew," MacDonald says. A Marine spokesman, Capt. David Nevers, says the Marine generals still believe that the V-22 is safe and the right aircraft to replace old troop-carrying helicopters. "Our faith in this aircraft has not wavered," says Nevers, although he adds that the Marines "recognize there is more to learn." MacDonald says the upcoming flight tests, which could take 18 months to two years, will answer the questions and, he believes, show that the V-22 can perform all the duties of comparable helicopters "and then some." The tests to check out the vortex ring state and maneuver issues, are not scheduled to begin until late summer or fall, when a specially modified V-22, heavily instrumented for the purpose is ready to fly.
Bob Cox, (817) 390-7723 [email protected]
Briefings to the Blue Ribbon Panel are available at www.acq.osd.mil/sts/v22/archives.htm
Professor Leishman's paper on vortex ring state: www.enae.umd.edu/AGRC/aero.html.
From this link
It had never occurred to anyone that just one rotor might stall and cause the V-22 to roll. "It's something was that was not on our radar screen at all," said MacDonald, the flight test pilot. (The Marines' handling of the crash investigation is the subject of an inquiry by the Pentagon's inspector general, after a Marine officer alleged improper actions by other officers. A Marine spokesman says the allegations do not affect the conclusion about the cause of the crash.)
In the months after the crash, Bell and Boeing began the special flight tests at Pax River to explore the vortex ring state. That testing was only partially complete when all V-22s were grounded after the December 2000 crash. Bell and Boeing, in their reports to the review panels, say the tests show that the V-22 can recover from a roll if the pilot simply rolls the engines forward to gain speed. But that can take seconds and hundreds of feet of altitude - time and space that even MacDonald concedes may not be available. "If you're close to the ground, it's a bad thing," the Boeing pilot says.
Based on the limited flight testing, the Marines and Bell/Boeing insist that the vortex ring state will not be a problem if the V-22 is flown within the prescribed limits. The V-22 flight manual says pilots should descend no faster than 800 feet per minute when flying at speeds of 40 knots or less - a slow, gradual descent not unlike that of a commercial airliner. MacDonald agrees with that guideline, although he says much more flight testing is needed.
"We're going to do a whole lot more of that when we get back to flying," he said. But the experts who've raised concerns about the V-22 say other test data presented in reports to the review panels strongly indicates that controlling the rate of descent does not eliminate the vortex ring state.
Flight simulator tests show that even with much slower descent, trying to maneuver a V-22 abruptly - making a hard turn or a sudden pull-up to abort a landing - could cause it to roll. Evidence of this was included in a special presentation that NASA's McDonald made to Aldridge in August. That presentation, which has not been made public but was obtained by the `Star-Telegram,' shows that in a simulator test the boundary between safe flight and vortex ring state all but disappears when a maneuver is attempted. Still other simulator tests show that when a pilot attempts an abrupt maneuver, the V-22 may spin out of control in as little as two or three seconds.
That's not much of a margin for error, says Coyle, whose office presented the data to the Blue Ribbon Panel. "A point we made ... was when a pilot is doing a quick stop maneuver, a pull-up, it's because something else is going on," Coyle says. "He's being shot at or he's trying to rescue someone. He's concentrating. If in the midst of that concentration something else occurs, he may not be able to react." In the Arizona accident, the pilot flying the V-22 did not lose control until he tried to turn the airplane to stay in formation.
Boeing's MacDonald concedes that, in theory at least, maneuvers could narrow the safety margin. "We're not sure," he says. "We don't believe it's significant. But we're going to test the hell out of that." When shown the charts that suggest that hard maneuvers could cause the V-22 to stall and roll, several retired Bell test pilots and engineers who worked on the V-22 said the aircraft was not designed for hard maneuvers and should not be flown that way. But Grady Wilson, a combat veteran of the Vietnam War and a former V-22 test pilot for Boeing, said that telling an Osprey pilot he can't maneuver in the heat of battle or even the chaos of military operations is unrealistic.
Wilson agrees that the V-22's maneuverability needs to be thoroughly tested. "As I flew it, we babied it. You had to be really gentle with it." Leishman, the Maryland professor, used a computer to simulate what happens with the rotors of helicopters and an aircraft like the V-22. His findings, in a paper recently published by the American Helicopter Society, show that a tilt-rotor aircraft has more complex aerodynamics than a helicopter. During rapid descent or maneuvers, he believes, it's typical for one rotor to get caught in the other's wake. When that happens the two rotors produce widely varying amounts of thrust.
"The thrust fluctuations lead to the roll response" long before the aircraft should reach vortex ring state, says Leishman, who briefed the NASA panel on his research. Leishman, Coyle and others say the V-22's problems may be related to something less exotic than vortex ring state: a propensity for the rotors to stall easily because they cannot generate enough extra thrust at critical moments to maneuver the airplane. Bell and Boeing engineers, in a written response provided to the `Star-Telegram,' denied that the V-22 is more prone to stall than helicopters. MacDonald says the V-22 will be capable of combat maneuvers. "We do expect people to be under duress in the operational world," he says, "and the aircraft has to be forgiving" of pilot mistakes. "The penalty for a good faith violation of a boundary can't be the loss of an aircraft and the crew," MacDonald says. A Marine spokesman, Capt. David Nevers, says the Marine generals still believe that the V-22 is safe and the right aircraft to replace old troop-carrying helicopters. "Our faith in this aircraft has not wavered," says Nevers, although he adds that the Marines "recognize there is more to learn." MacDonald says the upcoming flight tests, which could take 18 months to two years, will answer the questions and, he believes, show that the V-22 can perform all the duties of comparable helicopters "and then some." The tests to check out the vortex ring state and maneuver issues, are not scheduled to begin until late summer or fall, when a specially modified V-22, heavily instrumented for the purpose is ready to fly.
Bob Cox, (817) 390-7723 [email protected]
Briefings to the Blue Ribbon Panel are available at www.acq.osd.mil/sts/v22/archives.htm
Professor Leishman's paper on vortex ring state: www.enae.umd.edu/AGRC/aero.html.
From this link
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The author does a disservice by stating that 7 of 22 attempts at reproducing the problem situation drew long faces on the marines or people overlooking the test.. in all cases the maneuvers were done outside of the prescribed limits, i.e. pilot error!
I also dont agree with the military analysis that in the heat of battle you can't expect the pilot not to push the envelope. If you are on a motorcycle with a lot of power available you can't just wind on as much power as you like to get away from someone chasing you, but have to ride within the prescribed limits of available grip. Similarly the osprey should be flown with full awareness and within its limits.
Link, The V-22 tiltrotor
http://www.helicopterpage.com/html/tiltrotor.html
I also dont agree with the military analysis that in the heat of battle you can't expect the pilot not to push the envelope. If you are on a motorcycle with a lot of power available you can't just wind on as much power as you like to get away from someone chasing you, but have to ride within the prescribed limits of available grip. Similarly the osprey should be flown with full awareness and within its limits.
Link, The V-22 tiltrotor
http://www.helicopterpage.com/html/tiltrotor.html
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bliptune,
Regarding that link in your post, I don't know where the author got his info, but it is really inaccurate!
The author really does not understand the issues, and seems to mash up a bunch of rumors and partial answers into a dim understanding of the issues surrounding V-22 as we know it today.
For example, see his explanation of the autorotation issue, where he resolves it by proving that there are freewheel units in the drive train so everything is ok! The site is way too nieve to be of much use, I think.
Nick
Regarding that link in your post, I don't know where the author got his info, but it is really inaccurate!
The author really does not understand the issues, and seems to mash up a bunch of rumors and partial answers into a dim understanding of the issues surrounding V-22 as we know it today.
For example, see his explanation of the autorotation issue, where he resolves it by proving that there are freewheel units in the drive train so everything is ok! The site is way too nieve to be of much use, I think.
Nick
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Autorotate? Like a helicopter? Not so.
For example, see his explanation of the autorotation issue, where he resolves it by proving that there are freewheel units in the drive train so everything is ok! The site is way too nieve to be of much use, I think.
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V-22 details
I was just wondering at what speeds the conversions from helicopter to plane are and how they go about that.
Also about pilots having to push their aircraft in battle, I would have to say that the people who I have talked to and thinking about it myself, if you are underfire you wanna make yourself as hard a target as possible, coming down on approach to your LZ at a nice 40kts and not being able to manuever sounds pretty restrictive to me, And scary. Sure the A/C shouldn't be flown outside their limits but if the limits are this restrictive it just doesnt seem to lend itself well to combat.
Just my 2 cents.
Also about pilots having to push their aircraft in battle, I would have to say that the people who I have talked to and thinking about it myself, if you are underfire you wanna make yourself as hard a target as possible, coming down on approach to your LZ at a nice 40kts and not being able to manuever sounds pretty restrictive to me, And scary. Sure the A/C shouldn't be flown outside their limits but if the limits are this restrictive it just doesnt seem to lend itself well to combat.
Just my 2 cents.
Push the aircraft to its limits or beyond in combat?
I was only a tandem rotor trash hauller and not a gunship pilot but I am absolutely positive that at some time in history....each one of us did just that and usually more than just once. When the bullets start hitting home or streaking by your precious parts....combat pilots are going to do whatever they have to to avoid becoming battlefield debris.
We owe it to the future generation of American combat pilots to provide them with the very best in hardware to do their jobs. If the Osprey is unable to perform in such an environment then we should scrap the program. I say test the hell out of it...and determine exactly where the limits are and make a decision at that time without any consideration for reputations, political gain, or economical considerations for the manufacturer. The only criteria is that we provide our war fighters with the very best tools we can....something that will take them to the fight and bring them home again.
I was only a tandem rotor trash hauller and not a gunship pilot but I am absolutely positive that at some time in history....each one of us did just that and usually more than just once. When the bullets start hitting home or streaking by your precious parts....combat pilots are going to do whatever they have to to avoid becoming battlefield debris.
We owe it to the future generation of American combat pilots to provide them with the very best in hardware to do their jobs. If the Osprey is unable to perform in such an environment then we should scrap the program. I say test the hell out of it...and determine exactly where the limits are and make a decision at that time without any consideration for reputations, political gain, or economical considerations for the manufacturer. The only criteria is that we provide our war fighters with the very best tools we can....something that will take them to the fight and bring them home again.
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Just for the RECORD
Professor Leishman's papers seem to bear out exactly my early misgivings about the inherent aerodynamic flaws - including the hazards of not testing specifically and just number-crunching prosaically toward an expectation. I don't envy Tom McDonald now because it rightly falls to him to try and prove that it can be operated within safe limits - but I honestly doubt that it can - certainly not as a battlefield vehicle and IMHO, not even to a safe civil standard. I just hope he (TM) doesn't find out the hard way. I had heard about some of the frights that the TP's were having at Pax River and I really wonder how the system can morally expect them to press on with these tests without a bang-seat mod. John Farley says that an ejection seat could be fitted and that there is a design extant (maybe Boscombe Down or Martin Baker). I certainly would not go fly these trials without being properly "seated" and I doubt JF would either. It's just not fair to task people to do that, no matter how gradually you temper the profile and approach the problem.
AsymmVR is quite a lethal evolution - without considering the other hardware and software ailments that can crop up unannounced in flight-test, whether testing the boundaries of the envelope or not. Having a seat would be more than just "nice".
AsymmVR is quite a lethal evolution - without considering the other hardware and software ailments that can crop up unannounced in flight-test, whether testing the boundaries of the envelope or not. Having a seat would be more than just "nice".
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MV-22 Osprey Resumes Flying
(US Naval Air Systems Command May 29, 2002)
The MV-22 Osprey took to the skies today here for the first time after being grounded for over 17 months following the tragic Dec. 11, 2000 mishap. The first MV-22 test aircraft to resume flying has improvements in its hydraulic and flight control software systems that make it practically a brand new aircraft and the safest Osprey yet, according to V-22 program officials.
"The long awaited return to flight was a success. The Osprey not only performed what today’s test plan called for but exceeded our wildest expectations," said Col Dan Schultz, V-22 program manager. Today’s flight plan called for the aircraft to take off, hover, and land.
After successfully completing several vertical takeoffs, landings, and hovering maneuvers over the runway, the pilots conducted rearward and sideward flights to check the aircraft’s maneuverability in helicopter mode. The pilots gradually built up maneuver speeds up and down the runway, went into landing pattern circuits and began conversion work. Later in the afternoon, the Osprey’s encore performance included a full conversion to airplane mode at level flight speeds of 250 knots. The Osprey logged nearly two and one half hours of flight time today and returned in full up flight status.
Tom MacDonald and Bill Leonard, senior Bell Boeing V-22 Integrated Test Team pilots, who have a combined total of 13,000 flight hours in both fixed and rotary wing aircraft and over 500 hours each in the MV-22, took the aircraft through a series of maneuvers to evaluate its handling and performance. Part of this series included converting out from helicopter to airplane mode to take standard vibration measurements to check out the tracking and balance of the individual blades of the two proprotors. This "test card" for the first flight series follows the Osprey’s methodical and event driven approach to safely return the aircraft to flight testing.
"Along with everyone else on the V-22 test team, we are excited about being back in the flight test business. We are proud of the extensive safety and reliability enhancements to the Osprey’s design, which was made possible by the concerted efforts of many people throughout the NAVAIR, Bell Boeing, Rolls Royce and supporting contractor teams," asserted MacDonald.
Leonard shares the excitement of being back in the air and moving forward with flight testing. "I'm dedicated to the concept and believe tilt rotor technology will be as important to aviation as the advent of the jet engine. This aircraft has potential that we in the aviation community have yet to understand let alone exploit. I've been actively engaged in military and civilian aviation for over 35 years, flown well over 100 different aircraft and truly believe that this technology, if exploited properly, will impact both civil and military aviation to an incredible degree."
Today’s flight marks the beginning of an 18-month developmental flight test plan here that will validate the engineering and design changes made to the aircraft and continue with developmental testing that will further test such areas as vortex ring state boundaries, dynamic shipboard compatibility, formation flying, and low speed hovering and landing conditions. Other areas to be tested include the aircraft’s icing, cargo handling and radar warning systems. A total of 1800 flight test hours are scheduled over this period of time using seven MV-22 aircraft.
Good job guys.
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Great news..I agree they should thrash them well above their limits,really beat them about and see what it can really handle.
I think it`ll be a success.fingers crossed.
I think it`ll be a success.fingers crossed.
Tilt Rotors
I was lucky enough to have the opportunity to fly a XV-15 Tilt-Rotor in a high fidelity research simulator yesterday and it got me thinking.....
I have never been a big fan (geddit BIG FAN) of the tilt rotor concept at all, its not a good aeroplane, and its a terrible helicopter. So is it worth the technical difficultly?
With the ERICA and EUROTILT programs and the V22 & BA609 supposidy on the way, sooner or later some of us will be asked/expected to fly these things so I though it might be a good time to have a general chat about them.
I'll start things of with my two-cents....
Starting from the ground and then lifting into the hover and doing a spot of hover-taxiing I found the XV-15 to be really easy to fly (admittly I was getting lots of help from the spurious black boxes on board) but even so no big deal....very stable. The thing was very docile in yaw....lot's of pedal required to get it turning on the spot thanks to the tonne of engine and prop at the end of each wing! Flying around was just as easy and VERY VERY fast 260kts!
I have often wondered how the controls are laid out in a Tilt rotor - it's actually really neat, the collective remains as a collective in all flight regimes - up and down in helicopter mode and fast or slow in plane mode. The cyclic is a cyclic in heli mode but converts to being a stick/yoke in plane mode - the electronics handle the blending of the controls in transient speed ranges. The nacelle tilt in this set-up was handled by a coolie hat switch on the cyclic - three positions.
While everything was easy enough with an instructor talking me through the systems as I flew, I can't help thinking that the failure modes for these things are so much more complex. So complex in fact that the pilot wouldn't be able to react quick enough (to a complecated situation) to be able to do anything useful.
Furthermore, the differential ring vortex problem will also no doubt be a real danger for these craft, bank in helicopter mode at low forward speed and all of a sudden one rotor is in ring vortex state - WOLLOP.....Ouch!
I've also heard lot's of mutterings that the range and payload of real incarnations of these aircraft are also marginal.
What do you think......are they worth the bother? Would you fly them? Would you tell your granny to fly in one? Any real tilt rotor pilots out there?
CRAN
I have never been a big fan (geddit BIG FAN) of the tilt rotor concept at all, its not a good aeroplane, and its a terrible helicopter. So is it worth the technical difficultly?
With the ERICA and EUROTILT programs and the V22 & BA609 supposidy on the way, sooner or later some of us will be asked/expected to fly these things so I though it might be a good time to have a general chat about them.
I'll start things of with my two-cents....
Starting from the ground and then lifting into the hover and doing a spot of hover-taxiing I found the XV-15 to be really easy to fly (admittly I was getting lots of help from the spurious black boxes on board) but even so no big deal....very stable. The thing was very docile in yaw....lot's of pedal required to get it turning on the spot thanks to the tonne of engine and prop at the end of each wing! Flying around was just as easy and VERY VERY fast 260kts!
I have often wondered how the controls are laid out in a Tilt rotor - it's actually really neat, the collective remains as a collective in all flight regimes - up and down in helicopter mode and fast or slow in plane mode. The cyclic is a cyclic in heli mode but converts to being a stick/yoke in plane mode - the electronics handle the blending of the controls in transient speed ranges. The nacelle tilt in this set-up was handled by a coolie hat switch on the cyclic - three positions.
While everything was easy enough with an instructor talking me through the systems as I flew, I can't help thinking that the failure modes for these things are so much more complex. So complex in fact that the pilot wouldn't be able to react quick enough (to a complecated situation) to be able to do anything useful.
Furthermore, the differential ring vortex problem will also no doubt be a real danger for these craft, bank in helicopter mode at low forward speed and all of a sudden one rotor is in ring vortex state - WOLLOP.....Ouch!
I've also heard lot's of mutterings that the range and payload of real incarnations of these aircraft are also marginal.
What do you think......are they worth the bother? Would you fly them? Would you tell your granny to fly in one? Any real tilt rotor pilots out there?
CRAN
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V-22 and VRS. A question
The USMC has stated that if the V-22 enters a VRS situation it can be easily corrected by tilting the rotors 15 degrees which they state takes about 2 seconds.
My question for the experts is, can the V-22 encounter VRS while in a hover and especially in a moderate headwind? My reason for asking is what happens if the V-22 enters VRS while making a hoist pick-up over water or land where it must maintain a fixed position.
My question for the experts is, can the V-22 encounter VRS while in a hover and especially in a moderate headwind? My reason for asking is what happens if the V-22 enters VRS while making a hoist pick-up over water or land where it must maintain a fixed position.
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No.
Entering VRS requires a descent, the rate of which depends on disk loading and power applied.
VRS is a risk in all rotorcraft, pilots must be able to identify the incipient stages, know the corrective actions, and fly in profiles which prevent it from happening. Problem with the V22 is that it has demonstrated rapid catastrophic results that weren't originally anticipated (to the best of my knowledge).
I expect that VRS will not be a player in the future of V22 flight if training and procedures are appropriate.
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Matthew.
[email protected]
PS. Welcome back, Lu.
Entering VRS requires a descent, the rate of which depends on disk loading and power applied.
VRS is a risk in all rotorcraft, pilots must be able to identify the incipient stages, know the corrective actions, and fly in profiles which prevent it from happening. Problem with the V22 is that it has demonstrated rapid catastrophic results that weren't originally anticipated (to the best of my knowledge).
I expect that VRS will not be a player in the future of V22 flight if training and procedures are appropriate.
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Matthew.
[email protected]
PS. Welcome back, Lu.
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From memory the BIG problem for the V-22 when VRS is encountered is that it can happen on one side and not on the other, and I remember that this was the complexity in one of the accidents causing an uncontrolable roll from which the normal recovery action, that of going for forward speed/reducing pitch was not going to work. I would have expected the design staff to have looked at this occurrance and put in a computer programme to either limit the pilots choices (thereby avoiding the situation developing) when selecting a near VRS situation or putting in warning bells to alert of the onset of VRS.
Like all new flying consepts there is a lot to learn and its is either resolved by special flying techniques or by engineering.
There must be handling characteristics inherent in the V-22 which havent yet showed themselves. Thus it will be a long tough learning curve over the next years.
Incidentally does the rotor system have flapping hinges of any sort?
Like all new flying consepts there is a lot to learn and its is either resolved by special flying techniques or by engineering.
There must be handling characteristics inherent in the V-22 which havent yet showed themselves. Thus it will be a long tough learning curve over the next years.
Incidentally does the rotor system have flapping hinges of any sort?
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Yes and a lot more.
To: Tail Bloater
The Prop Rotor has lead and lag capabilities as well as feathering and flapping. The entire Prop Rotor has this capability essentially because the hub is made of rubber much like the elastomeric feathering bearings on some helicopters. The hub acts as a constant velocity joint, which minimizes if not, eliminates lead and lag but still allows feathering and flapping. The hub, at least when I worked on the program, has flapping sensors which send a signal to the flight computer. The flight computer in turn signals the flight control servos to cancel out the flapping much like a pilot of a conventional helicopter would do when moving forward from a hover.
I personally believe the following. 1) The V-22 is in a hover condition for a low proportion of the flight envelope. 2) Most pilots fear the fly-by-wire system and instead of flying the helicopter forward they will tilt the pods forward several degrees. 3) The overall life cycle of the hydraulic system including the servos is predicated by the low use of the servos while in the helicopter mode. When in the airplane mode the servos are in a fixed position dictated by the pilot (Prop pitch) and are assumed to remain stationary in the selected position. 4) When the aircraft maneuvers the Prop Rotor will respond like a gyroscope rotor and precess. The flap sensors will sense this and will be in almost constant motion trying to correct this condition. 5) If the flap sensors do not respond quickly enough the rotors will precess and the thrust line will go off axis causing control problems.
Even if the control problem is not manifested the hydraulics will be working overtime reducing system reliability from what was guaranteed by the contractor.
IMHO
Incidentally does the rotor system have flapping hinges of any sort?
I personally believe the following. 1) The V-22 is in a hover condition for a low proportion of the flight envelope. 2) Most pilots fear the fly-by-wire system and instead of flying the helicopter forward they will tilt the pods forward several degrees. 3) The overall life cycle of the hydraulic system including the servos is predicated by the low use of the servos while in the helicopter mode. When in the airplane mode the servos are in a fixed position dictated by the pilot (Prop pitch) and are assumed to remain stationary in the selected position. 4) When the aircraft maneuvers the Prop Rotor will respond like a gyroscope rotor and precess. The flap sensors will sense this and will be in almost constant motion trying to correct this condition. 5) If the flap sensors do not respond quickly enough the rotors will precess and the thrust line will go off axis causing control problems.
Even if the control problem is not manifested the hydraulics will be working overtime reducing system reliability from what was guaranteed by the contractor.
IMHO
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The present situation is that everything is on hold. Bell has said the 609 program will be held up pending the outcome of the V22 program. Until the V22 is bought & delivered, don't expect any further development on the 609. It's years away from certification in the best case, completely dead in the worst.
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Osprey crew cautioned - but not grounded
U.S. Naval Air Systems Command (NAVAIR) officials confirmed that a test V-22 Osprey flew an unapproved route around Washington DC, but said the pilots have not been grounded. The aircraft - Osprey #21 - apparently strayed from its flight test route December 17. ‘The pilots made the diversion during a programmed test sortie from Pax River,’ says Ward Carroll, the test center’s spokesman.
Carroll says the pilots were cautioned ‘for extremely poor headwork’ by officials after the flight, but the flight itself was within NAVAIR guidelines. He said possible complications caused by the Osprey flying into Washington’s temporary flight restriction (TFR) area - imposed as the result of 9/11- had not been an issue. ‘The FAA has not been involved at all.’
But he could not explain how the aircraft was able to divert from an IFR flight plan to make a circular tour of the Pentagon. Such maneuvers are strictly banned under the terms of the TFR Carroll said no such flight route would be used again by an Osprey test crew.
The flight caused raised eyebrows. NAVAIR is currently processing a ‘Congressional inquiry’ from one Congressman who observed the aircraft. The Osprey is a ‘hot button’ issue in Washington DC following its recent record of accidents. It is currently under intense scrutiny- politically and operationally - during testing of alleged performance flaws.
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[b]In a separate incident over Washington >>>>>>
Two F-15s were dispatched to investigate a television station's helicopter as it flew into controlled airspace, the apparent result of a communications failure between the pilot and the federal agencies that patrol the skies.
The WRC-TV (Channel 4) helicopter departed an airfield near Baltimore at about 10:15 a.m. The helicopter, which the station has dubbed Chopper 4 was sent up with a photographer to shoot live video of a traffic backup on Interstate 270.
"The F-15s were sent up to eyeball it. They determined it represented no threat," said Army Maj. Barry Venable, spokesman for the North American Aerospace Defense Command, a joint United States-Canadian military agency that patrols the skies around Washington.
The WRC crew was able to continue its work, station spokeswoman Angela Owens said.
The Federal Aviation Administration will investigate the incident, spokesman Greg Martin said.
Ms. Owens said there was a communications failure, but she did not know if it was human or mechanical.
News and traffic helicopters have been restricted from flying within a 15-mile radius of the Washington Monument since the September 11 terrorist attacks. This month, the FAA extended the area an additional 30 miles when federal authorities issued a Code Orange terrorism alert.