Civil tilt rotors
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Civil tilt rotors
Ok call me a fat, unadventurous, unimaginative snob....
But I think that if I was the kind of high net worth individual they're aiming the 609 at, I'd really rather fly from heliport to airfield on a nice, spacious S76, AW139 or Bell 222 and then be decanted to my waiting Gulfstream than to duck and wriggle into the cramped confines of the 609, unless I was going to be sitting behind the stick.
And if the whole Vortex Ring issue has come quite so close to scuppering military tilt rotor ops, can we really believe that a civil tilt rotor will be accepted (even if it somehow gets certificated) by enough people to make it a goer?
Feel free to point out where I'm going wrong, please!
But I think that if I was the kind of high net worth individual they're aiming the 609 at, I'd really rather fly from heliport to airfield on a nice, spacious S76, AW139 or Bell 222 and then be decanted to my waiting Gulfstream than to duck and wriggle into the cramped confines of the 609, unless I was going to be sitting behind the stick.
And if the whole Vortex Ring issue has come quite so close to scuppering military tilt rotor ops, can we really believe that a civil tilt rotor will be accepted (even if it somehow gets certificated) by enough people to make it a goer?
Feel free to point out where I'm going wrong, please!
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Maybe it'll be like the Starship. A fantastic, underappreciated machine. I'll buy up the entire production run of 22 or so for cheap, and have an unlimited supply of parts for when I need. 
Does the 609 have the same autorotative capability as the Osprey......as in "none"?
1. LACK OF AUTOROTATION CAPABILITY
Although it was initially believed that V-22 would have a full autorotation capability, it is now generally agreed that the V-22 cannot autorotate in any practical sense. Although the V-22 has performed an autorotation in a technical sense, the test procedure was carefully structured to allow for a safe entry (the engine power was slowly removed to allow the aircraft to establish a stable autorotation.) In a practical autorotation, the aircraft must be able to enter a stable autorotative state following an abrupt power interruption. Although an abrupt removal of engine power in V-22 has never been done, such an event would probably result in loss of control because of the inability to maintain rotor RPM. This is especially true if the failure occurs in transition mode (60 deg nacelles)[1], the common configuration used for “slinging” external loads.
The single autorotation test in V-22 also demonstrated that the attempt to recover from autorotation to a safe landing by using stored rotor energy to arrest the rate of descent failed markedly. The test data indicate that the aircraft would have impacted the ground at a rate of descent of about 3700 ft/min (61.7 ft/sec) ¾ a fatal rate-of-descent. Authoritative proponents, e.g., the NASA Review Team, have argued that autorotation is not a needed capability for the V-22 due to the low probability of a two-engine failure. My analysis of Navy safety data shows that the Navy/USMC experiences a dual engine failure in a helicopter about once every 3 to 4 years due to fuel contamination onboard a ship. Historically, such accidents have usually been survivable because the helicopter autorotates into the water and the crew and passengers quickly scramble out. If such an event were to occur in V-22, it will probably be fatal to crew and passengers because the aircraft will not smoothly enter autorotation, but most probably depart from controlled flight, and because the cabin is too cramped for a rapid egress.
We know from the combat record in Vietnam[2] that many ground fire hits on a helicopter result in a need for an immediate autorotation. Of the 3,000 or so helicopters lost during the Vietnamese conflict, fully 80 to 90 percent were lost on approach to landing (i.e., where V-22 would be operating in helicopter mode), approximately half safely autorotated to the ground, thereby saving the crews. Even though the V-22 rotors are interconnected, some combat fire hits can be expected to result in loss of both an engine and the rotor interconnection. Such combat events in V-22 would be fatal.
Autorotation is to a helicopter pilot (and his passengers) what an ejection seat is to a fighter pilot. When everything goes wrong, as it often does in a combat environment, autorotation is all a helicopter pilot has to save his and his passenger’s lives. As good as the V-22’s survivability features may be (and they are very good), there will still be times when everything does go wrong; at those times autorotation could be the difference between a chance for survival and a fatal outcome. The lack of autorotation capability in V-22 is inherent in this tilt-rotor design given current technology options. The mission advantages provided by the tilt-rotor design, such as long range and high speed, afford survivability advantages during the ingress portion of a mission, but for landings into a hot zone, the lack of autorotation capability is an important factor whose consequences should be clearly understood.
In my view, V-22 fails to meet the ORD threshold requirement to be able conduct a “survivable emergency landing with all engines inoperative” over a large portion of its operational envelope – helicopter mode flight below about 2000 above ground level. From higher altitudes, or when operating in airplane it is generally believed that V-22 is capable of conducting a survivable, all engines-inoperative emergency landing, although considerable risk is incurred in such a maneuver because of the very high sink rate of V-22 and the high airspeed needed for the maneuver.
Although it was initially believed that V-22 would have a full autorotation capability, it is now generally agreed that the V-22 cannot autorotate in any practical sense. Although the V-22 has performed an autorotation in a technical sense, the test procedure was carefully structured to allow for a safe entry (the engine power was slowly removed to allow the aircraft to establish a stable autorotation.) In a practical autorotation, the aircraft must be able to enter a stable autorotative state following an abrupt power interruption. Although an abrupt removal of engine power in V-22 has never been done, such an event would probably result in loss of control because of the inability to maintain rotor RPM. This is especially true if the failure occurs in transition mode (60 deg nacelles)[1], the common configuration used for “slinging” external loads.
The single autorotation test in V-22 also demonstrated that the attempt to recover from autorotation to a safe landing by using stored rotor energy to arrest the rate of descent failed markedly. The test data indicate that the aircraft would have impacted the ground at a rate of descent of about 3700 ft/min (61.7 ft/sec) ¾ a fatal rate-of-descent. Authoritative proponents, e.g., the NASA Review Team, have argued that autorotation is not a needed capability for the V-22 due to the low probability of a two-engine failure. My analysis of Navy safety data shows that the Navy/USMC experiences a dual engine failure in a helicopter about once every 3 to 4 years due to fuel contamination onboard a ship. Historically, such accidents have usually been survivable because the helicopter autorotates into the water and the crew and passengers quickly scramble out. If such an event were to occur in V-22, it will probably be fatal to crew and passengers because the aircraft will not smoothly enter autorotation, but most probably depart from controlled flight, and because the cabin is too cramped for a rapid egress.
We know from the combat record in Vietnam[2] that many ground fire hits on a helicopter result in a need for an immediate autorotation. Of the 3,000 or so helicopters lost during the Vietnamese conflict, fully 80 to 90 percent were lost on approach to landing (i.e., where V-22 would be operating in helicopter mode), approximately half safely autorotated to the ground, thereby saving the crews. Even though the V-22 rotors are interconnected, some combat fire hits can be expected to result in loss of both an engine and the rotor interconnection. Such combat events in V-22 would be fatal.
Autorotation is to a helicopter pilot (and his passengers) what an ejection seat is to a fighter pilot. When everything goes wrong, as it often does in a combat environment, autorotation is all a helicopter pilot has to save his and his passenger’s lives. As good as the V-22’s survivability features may be (and they are very good), there will still be times when everything does go wrong; at those times autorotation could be the difference between a chance for survival and a fatal outcome. The lack of autorotation capability in V-22 is inherent in this tilt-rotor design given current technology options. The mission advantages provided by the tilt-rotor design, such as long range and high speed, afford survivability advantages during the ingress portion of a mission, but for landings into a hot zone, the lack of autorotation capability is an important factor whose consequences should be clearly understood.
In my view, V-22 fails to meet the ORD threshold requirement to be able conduct a “survivable emergency landing with all engines inoperative” over a large portion of its operational envelope – helicopter mode flight below about 2000 above ground level. From higher altitudes, or when operating in airplane it is generally believed that V-22 is capable of conducting a survivable, all engines-inoperative emergency landing, although considerable risk is incurred in such a maneuver because of the very high sink rate of V-22 and the high airspeed needed for the maneuver.
Avoid imitations
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I've followed this project since the concept was first publicised, about thirty years ago. It seemed a great idea back then but the practical disadvantages (low payload, tricky handling at low speed, huge cost) unfortunately seem to outweigh the benefits of the higher cruise speed. It was meant to be a thoroughbred but somehow it now seems to have turned out to be more of a mongrel.
I forsee that it will be unable to use many UK helipads, often confining it to airfields - in which case a simple turbo-prop could be used.
Will it ever gain certification in UK? I now have grave doubts about this.
To be quite honest, as the holder of both rotary and fixed wing professional licences, I'm not sure I'd want to operate it.
I'd far rather put my stake money on the long overdue re-emergence of the Autogyro, utilising tip jet drive for low speed work, which is inherently safer, has a far better payload and can be made far cheaper yet still use small helipads (bring back the Fairey Rotodyne http://www.helis.com/50s/h_rotdyn.php ).
I forsee that it will be unable to use many UK helipads, often confining it to airfields - in which case a simple turbo-prop could be used.
Will it ever gain certification in UK? I now have grave doubts about this.
To be quite honest, as the holder of both rotary and fixed wing professional licences, I'm not sure I'd want to operate it.
I'd far rather put my stake money on the long overdue re-emergence of the Autogyro, utilising tip jet drive for low speed work, which is inherently safer, has a far better payload and can be made far cheaper yet still use small helipads (bring back the Fairey Rotodyne http://www.helis.com/50s/h_rotdyn.php ).
This link will take you to the article from which I quoted previously.
http://www.g2mil.com/V-22safety.htm
Within the article are links to additional articles that pertain to the discussion of tilt rotors.....each reader is left to their own to determine the validity of the arguments set forth.
I have been hanging around MCAS Cherry Point lately and have talked to a few Marine aviators who, shall we say, sing not of the prowess of the Osprey.
http://www.g2mil.com/V-22safety.htm
Within the article are links to additional articles that pertain to the discussion of tilt rotors.....each reader is left to their own to determine the validity of the arguments set forth.
I have been hanging around MCAS Cherry Point lately and have talked to a few Marine aviators who, shall we say, sing not of the prowess of the Osprey.
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Tilt-rotor
Interleaving Now who has half a billion dollars available for the development of the Interleaving?
Dave, the problem is that the money has already been spent on the tilt-rotor and there's no changing horses now. Remember, funding for Bell's tiltrotor goes all the way back to their first military development contract in 1953 (see XV-3). So waaaay too much money has been spent on this concept to abandon it now. By God, we're GOING to make it work!
In the 1950's, helicopters were maybe 100 knot machines. Someone, somewhere once upon a time got convinced that vectored-thrust was the "wave of the future...it just has to be!" And the funding fun began!
And since vectored-jet-thrust (e.g. Harrier) is impractical for civilian use, it leaves us with the only alternative: vectored helicopter thrust. Okay, but what to do about those big o'l dang proprotors hanging down below the fuselage? Well they started off big (like real helicopter rotors) but that didn't work that well, so they got smaller and smaller. And finally they got so small that autorotation capability went out the window. And they still stick down below the fuselage! Oh well...
Yeah, but. Proponents will say, "Yeah...but...is the ability to autorotate really a big deal? How many dual engine-failures do we hear about in King Airs?" Okay, so autorotative capability may or may not be an issue depending on how successfully the marketing guys can overcome the slight perception that the 609 is a helicopter. "Hey, it's a King Air that only spends 0.00000001% of its time hovering! Whaddya worried about?"
Along with the small-diameter proprotors comes high downwash velocities (and not insignificantly, high noise from all the horsepower needed to lift the thing to a hover). So let's cut the crap - you won't be seeing too many 609's operating out of smallish "heliports," even the existing ones in industrial parks if they are surrounded by residential areas. The tiltrotor, when not operating form an airport is going to need room...LOTS of room. No steep, slow approaches for this baby! Why not?
A-VRS. A-VRS? Yeah, "asymmetric" vortex ring: one in/one out. Well, that's either an issue or not depending on who you want to believe. The manufacturer and the military say that it's not an issue when the tiltrotor is operated within certain parameters. The infamous A-VRS crash in Marana, Arizona was a "fluke" they'll say. Never happen again! Well, they won't come out and actually say that, but they'll imply it. The trouble is, one bad A-VRS accident has already happened on what should have been a relatively routine formation landing that somehow got screwed up. Heh- we know that such "screw-ups" never happen in aviation, right? Never happen again! Umm yeah, maybe.
Let's be honest - getting into A-VRS at low altitude is pretty much unrecoverable. It'll hit the ground inverted or nearly so. It's fatal. Problem for you? The comparably-sized S-76 has gotten itself into some pretty strange accidents in its history while operating off-airport. Okay, so operating off-airport involves a certain amount of risk. And maybe, as that U.S. Marine guy recently alluded to, accidents are inevitable. ("Alluded to???" He came right out and flat said it!)
So "buying in" to a tiltrotor requires overcoming some strong helicopter philosophies and assumptions. Can this happen? It will be interesting to see.
I do know one thing: The first A-VRS accident of a civil Fortune 500 tiltrotor will kill it. If there is an accident in which A-VRS is even hinted at being a causal factor, it's dead. Especially if the accident occurs early in the operational history.
On the other hand! The lure of the tiltrotor concept may be strong enough to make it succeed where the aforementioned Beech Starship did not. The question is: Will it be enough for Bell to offset the development cost? On this, my personal jury is still out. I'm no fan of the tiltrotor concept - never have been. It's a bastard design that does nothing really well. It's just different.
People like to draw comparisons between the tiltrotor and the first helicopters and the skepticism that they are/were viewed. But I think that's not correct. The peculiar and unique capabilities of the helicopter were obvious and attractive from the start - if you consider the "start" Leonardo da Vinci's first designs.
The uses for and applications of the tiltrotor are not so readily apparent. Unless I'm missing something (and I'll admit that I'm no visionary). Not only that, it has some huge obstacles to overcome. Try as Bell might, I'm not sure the tiltrotor will ever be "ready for prime time" as they used to say. I mean, over 50 years of development hasn't even given us anything but a couple of prototype "proof-of-concept" models that - at least the ones that haven't crashed - are relegated to museums.
Maybe we should give 'em another fifty years?
In the 1950's, helicopters were maybe 100 knot machines. Someone, somewhere once upon a time got convinced that vectored-thrust was the "wave of the future...it just has to be!" And the funding fun began!
And since vectored-jet-thrust (e.g. Harrier) is impractical for civilian use, it leaves us with the only alternative: vectored helicopter thrust. Okay, but what to do about those big o'l dang proprotors hanging down below the fuselage? Well they started off big (like real helicopter rotors) but that didn't work that well, so they got smaller and smaller. And finally they got so small that autorotation capability went out the window. And they still stick down below the fuselage! Oh well...
Yeah, but. Proponents will say, "Yeah...but...is the ability to autorotate really a big deal? How many dual engine-failures do we hear about in King Airs?" Okay, so autorotative capability may or may not be an issue depending on how successfully the marketing guys can overcome the slight perception that the 609 is a helicopter. "Hey, it's a King Air that only spends 0.00000001% of its time hovering! Whaddya worried about?"
Along with the small-diameter proprotors comes high downwash velocities (and not insignificantly, high noise from all the horsepower needed to lift the thing to a hover). So let's cut the crap - you won't be seeing too many 609's operating out of smallish "heliports," even the existing ones in industrial parks if they are surrounded by residential areas. The tiltrotor, when not operating form an airport is going to need room...LOTS of room. No steep, slow approaches for this baby! Why not?
A-VRS. A-VRS? Yeah, "asymmetric" vortex ring: one in/one out. Well, that's either an issue or not depending on who you want to believe. The manufacturer and the military say that it's not an issue when the tiltrotor is operated within certain parameters. The infamous A-VRS crash in Marana, Arizona was a "fluke" they'll say. Never happen again! Well, they won't come out and actually say that, but they'll imply it. The trouble is, one bad A-VRS accident has already happened on what should have been a relatively routine formation landing that somehow got screwed up. Heh- we know that such "screw-ups" never happen in aviation, right? Never happen again! Umm yeah, maybe.
Let's be honest - getting into A-VRS at low altitude is pretty much unrecoverable. It'll hit the ground inverted or nearly so. It's fatal. Problem for you? The comparably-sized S-76 has gotten itself into some pretty strange accidents in its history while operating off-airport. Okay, so operating off-airport involves a certain amount of risk. And maybe, as that U.S. Marine guy recently alluded to, accidents are inevitable. ("Alluded to???" He came right out and flat said it!)
So "buying in" to a tiltrotor requires overcoming some strong helicopter philosophies and assumptions. Can this happen? It will be interesting to see.
I do know one thing: The first A-VRS accident of a civil Fortune 500 tiltrotor will kill it. If there is an accident in which A-VRS is even hinted at being a causal factor, it's dead. Especially if the accident occurs early in the operational history.
On the other hand! The lure of the tiltrotor concept may be strong enough to make it succeed where the aforementioned Beech Starship did not. The question is: Will it be enough for Bell to offset the development cost? On this, my personal jury is still out. I'm no fan of the tiltrotor concept - never have been. It's a bastard design that does nothing really well. It's just different.
People like to draw comparisons between the tiltrotor and the first helicopters and the skepticism that they are/were viewed. But I think that's not correct. The peculiar and unique capabilities of the helicopter were obvious and attractive from the start - if you consider the "start" Leonardo da Vinci's first designs.
The uses for and applications of the tiltrotor are not so readily apparent. Unless I'm missing something (and I'll admit that I'm no visionary). Not only that, it has some huge obstacles to overcome. Try as Bell might, I'm not sure the tiltrotor will ever be "ready for prime time" as they used to say. I mean, over 50 years of development hasn't even given us anything but a couple of prototype "proof-of-concept" models that - at least the ones that haven't crashed - are relegated to museums.
Maybe we should give 'em another fifty years?
The Marana crash was a situation where number two in the formation got into a "fast and steep" situation after over-arc'ing on a night formation approach.
Now how many of us have experienced that really rare situation?
Throw in the lack of cabin space and the huge cost difference between Chinooks/Sikorsky's and the Osprey and one can only shake their heads in disgurst.
Last time we had a Texan in the office during a war, Bell helicopters flourished....funny how that happens!
Perhaps we should ask Nick about politics in aircraft procurement programs.
Now how many of us have experienced that really rare situation?
Throw in the lack of cabin space and the huge cost difference between Chinooks/Sikorsky's and the Osprey and one can only shake their heads in disgurst.
Last time we had a Texan in the office during a war, Bell helicopters flourished....funny how that happens!
Perhaps we should ask Nick about politics in aircraft procurement programs.
Civil Tilt Rotors
For FH1100 and SASless,
Sometime ago Nick Lappos offered some thoughts about whether the Marana crash was VRS or in reality quite a different aerodynamic situation. Maybe he will respond with that discussion here. In any case, postulating a vortex ring state boundary at 40 KIAS and -800 FPM and stating that boundary exists essentially for all helicopters flies in the face of all of the undersigned's experience in attempting to force helicopters into this state.
Sometime ago Nick Lappos offered some thoughts about whether the Marana crash was VRS or in reality quite a different aerodynamic situation. Maybe he will respond with that discussion here. In any case, postulating a vortex ring state boundary at 40 KIAS and -800 FPM and stating that boundary exists essentially for all helicopters flies in the face of all of the undersigned's experience in attempting to force helicopters into this state.
I'm sure Tom McDonald would beg to differ...
http://www.boeing.com/rotorcraft/mil...imes/nov03.pdf
http://www.boeing.com/rotorcraft/mil...imes/nov03.pdf
Originally Posted by ShyTorque
I'd far rather put my stake money on the long overdue re-emergence of the Autogyro, utilising tip jet drive for low speed work, which is inherently safer, has a far better payload and can be made far cheaper yet still use small helipads (bring back the Fairey Rotodyne http://www.helis.com/50s/h_rotdyn.php ).
The Groen brothers are attempting a resurgance of this concept:
http://www.groenbros.com/gyrodyne_tech.php
They seem to be actively recruiting people to join their effort.
-- IFMU
I have sat back and read the attacks on the V-22 and tiltrotor technology in general for many years now but the time has come to place my position here. I will qualify my comments by saying that I'm very intimate with the V-22 and whether or not it can perform the mission. Is it the greatest thing since sliced bread...NO but it is indeed a very impressive aircraft. I'll address SASless' comments first. Frankly, you don't have a clue with your comments and constant quoting of critics. Have you ever flown the aircraft or even the simulator? Have you ever actually spent time around the aircraft, the crews that fly it, or the people who maintain it? The critics will never accept the words of those involved with the program because they are dead set against it, regardless of how the answers are presented.
I'll state this plain and simple, VRS is no greater an issue in the V-22 than any helicopter!! You can argue the assymetrical issue all you want but the fact remains that the descent rates required to encounter VRS are quite large and you're already in a very bad situation if this occurs. Marana was a tragedy, a good friend of mine was killed there, but they simply put themselves into an extremely bad situation. The mandated tests after this mishap actually expanded the envelope.
Time and time again the critics argue the same issues over and over despite rejections from those more familiar with the machine. I'd be happy to back these critics if they would bring up some of the true drawbacks but they won't because they'll find that they are quite trivial compared to the "showstoppers" they like to harp about.
Another argument continues to revolve around comparable helicopters. Again, look at the facts. This aircraft was designed to replace one helicopter, the H-46. Cabin dimensions and number of troops is nearly identical. And despite what you want to say, the V-22 can take the H-46 load twice as far in the same amount of flight time, no doubt, it's been proven. Here's an example, the V-22 has been flown nearly the width of the US in less than 6 hours with one fuel stop and landed to a helipad. Name a helicopter that can equal those flight times. The critics will immediately think this was some rigged test but it wasn't, it was an actual training mission.
My last comments concern the men and women involved in the program. We are not liars or idiots. We do not have death wishes. We believe in the aircraft and are working are collective butts off to make it as capable as possible. Unfortunately we've been handcuffed by constant criticism and oversight and frankly have to walk on eggshells all the time. The critics will continue to whine and moan but the important thing to remember is this, very few of them have actually ever flown in or even seen a V-22 in person, you can justify their comments by that.
I'll state this plain and simple, VRS is no greater an issue in the V-22 than any helicopter!! You can argue the assymetrical issue all you want but the fact remains that the descent rates required to encounter VRS are quite large and you're already in a very bad situation if this occurs. Marana was a tragedy, a good friend of mine was killed there, but they simply put themselves into an extremely bad situation. The mandated tests after this mishap actually expanded the envelope.
Time and time again the critics argue the same issues over and over despite rejections from those more familiar with the machine. I'd be happy to back these critics if they would bring up some of the true drawbacks but they won't because they'll find that they are quite trivial compared to the "showstoppers" they like to harp about.
Another argument continues to revolve around comparable helicopters. Again, look at the facts. This aircraft was designed to replace one helicopter, the H-46. Cabin dimensions and number of troops is nearly identical. And despite what you want to say, the V-22 can take the H-46 load twice as far in the same amount of flight time, no doubt, it's been proven. Here's an example, the V-22 has been flown nearly the width of the US in less than 6 hours with one fuel stop and landed to a helipad. Name a helicopter that can equal those flight times. The critics will immediately think this was some rigged test but it wasn't, it was an actual training mission.
My last comments concern the men and women involved in the program. We are not liars or idiots. We do not have death wishes. We believe in the aircraft and are working are collective butts off to make it as capable as possible. Unfortunately we've been handcuffed by constant criticism and oversight and frankly have to walk on eggshells all the time. The critics will continue to whine and moan but the important thing to remember is this, very few of them have actually ever flown in or even seen a V-22 in person, you can justify their comments by that.
Civil Tilt Rotors
For 212 Man,
Actually I don't recollect that Tom made the statement that the 40 KIAS/-800FPM boundary existed for all helicopters as well. I believe it was the program folks. Tom MacDonald was a USN pilot attached to the NAVPRO at Sikorsky and is well remembered by the undersigned as a very fine aviator and an upstanding gentleman. He has a lot of experience in the 53E as I recall, and I'd bet that if you asked him if he could enter VRS at 40kt/-800 fpm in the E........
And if the 40kt/-800 fpm boundary existed for all the rest of the helicopter fleets, you'd think that all of those flight manuals would be in revision.
Not an anti tilt rotor person, as I believe that the market place will see the reality of its advantages and costs ( not $ ) soon enough, as Nick's notes imply.
Actually I don't recollect that Tom made the statement that the 40 KIAS/-800FPM boundary existed for all helicopters as well. I believe it was the program folks. Tom MacDonald was a USN pilot attached to the NAVPRO at Sikorsky and is well remembered by the undersigned as a very fine aviator and an upstanding gentleman. He has a lot of experience in the 53E as I recall, and I'd bet that if you asked him if he could enter VRS at 40kt/-800 fpm in the E........
And if the 40kt/-800 fpm boundary existed for all the rest of the helicopter fleets, you'd think that all of those flight manuals would be in revision.
Not an anti tilt rotor person, as I believe that the market place will see the reality of its advantages and costs ( not $ ) soon enough, as Nick's notes imply.
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The Incredable "Flying Pork Rind"!
Yes, the AF sees the V-22 as just another Cessna Citation that will OCCASIONALY need to hover, but that's not what the MC needs or wanted but was sold on. The AF does a lot of flying from one protected place to a far-off hostile place, hover then head back. The MC needs the V-22 to act like a pogo stick and that is where the V-22 fails. I read elsewhere the AF V-22 could live with one set of tires a year whereas the MC would need to change them out monthly. Yes, it has accumulated a lot of straight and level flights and impressed all with it's great acceleration but it was supposed to be a replacement for perhaps the MC's best combat proven A/C ever, the H-46. The frog jumps from the boat to shore and back 3 or 4 times an hour ALL day and night. It lands in the dirt and mud and always comes back aboard filthy but flyable. It does hop after hop, sometimes taking off and landing a dozen times an hour. Medivacs in hot LZs, gunners pouring out lead in defense from both sides, wounded on the cable and internals wider than a pallet. Pogo stick versus a flying broom stick. Yep, the AF has something they can get by with but the MC is screwed!. BTW, I'm a H-53 guy.
mckpave says: "I'll state this plain and simple, VRS is no greater an issue in the V-22 than any helicopter!!"
Nice sound bite, but wrong. Plainly and simply, wrong.
When we think of VRS in helicopters, it is an event triggered by the vertical movement of the fuselage and rotor system together. The reason that tiltrotors are more susceptible to VRS (and its killer relative, A-VRS) is that you can tilt the nacelles rearward while the fuselage is still in forward flight. Thus, the inflow that the proprotors are seeing can be more "vertical" that might be apparent to the pilot. This is why the tiltrotor can get into VRS with forward airspeed while a helicopter needs to be below ETL.
While practicing VRS entries in a helicopter, it is impossible to know when the rotor will "break." It will do it when conditions are exactly right for itself, and it may not happen at exactly the same parameters every time. That is the chaotic nature of a rotor system. We pilots understand this.
If a tiltrotor aircraft enters VRS, there is no guarantee that both proprotors will go into it at the same time...or even that both of them will. The prospect of only one proprotor entering VRS at low altitude is horrifying. If the pilot does not immediately recognize that one proprotor is on the edge of VRS (as happened to Majors Brow and Gruber that night in Marana), his instinctive, natural reaction will be to counter any roll excursions with opposite stick, increasing the pitch of the down-going proprotor - just the exact wrong it needs.
Now maybe I'm totally wrong and it wasn't A-VRS at all. Whatever was the true cause of the Marana crash, it is clear that the V-22's roll rate exceeded the ability of the pilots to control it that fateful night. They were decellerating and decending...had the nose up and the nacelles tilted aft. Suddenly it rolled over and dove for the ground. Inexplicable, "one in a million" type of accident? Maybe. Let us hope so. But the fact that it happened once should tell us that it will happen again. Pilots sometimes do dumb things, no matter how many rules, guidelines, limitations and/or procedures are put in place to guard against them. Or maybe they're just inexperienced, or have low make/model time. Whatever. Don't believe me? Check out YouTube. Type in "Aircraft Crashes" to the search field.
I'm sure that all of the people working on the V-22 program have a lot of themselves invested in it. I'm sure they feel very emotionally involved, and take criticism of the aircraft personally. I'm also sure it's an exciting, fun aircraft to fly. Its capabilities are awesome.
But critics need not be expert V-22 pilots to comment on the design. And the critics have to ask, "As fantastic a flying machine as it is, do we really need this thing as a combat aircraft?"
Now me, I won't comment on the fact that after all this time the V-22 still doesn't have a gun. Maybe the Marines will be clairvoyant enough to know that every LZ they send the aircraft to will be enemy-free with no possibility of hostile fire. Let's hope so!
And me, I won't comment on the NAVAIR website figure that the HOGE altitude limit is a mere 5,000 feet. I guess the Marines and Air Force only plan to use the V-22 in relatively low altitude, desert-type scenarios. Let's hope all future wars are held at sea level.
And come to think of it, what altitude is considered "HOGE" for the V-22? How high can it hover and still be IGE? I would imagine/guess that every landing will involve at least some OGE time. Or maybe not, who knows what techniques they'll use when push comes to shove?
I really hadn't planned on commenting on the V-22. But some of its performance characteristics are relevant to the 609. Plus, I just don't think that people should be barred from saying anything about it simply because they haven't flown it. It's not a magic machine. It's an aircraft, plain and simple. Sure, it's an aircraft with some unique capabilities. How it will be used, and how well it will do in those uses are still in question, if not in doubt.
Nice sound bite, but wrong. Plainly and simply, wrong.
When we think of VRS in helicopters, it is an event triggered by the vertical movement of the fuselage and rotor system together. The reason that tiltrotors are more susceptible to VRS (and its killer relative, A-VRS) is that you can tilt the nacelles rearward while the fuselage is still in forward flight. Thus, the inflow that the proprotors are seeing can be more "vertical" that might be apparent to the pilot. This is why the tiltrotor can get into VRS with forward airspeed while a helicopter needs to be below ETL.
While practicing VRS entries in a helicopter, it is impossible to know when the rotor will "break." It will do it when conditions are exactly right for itself, and it may not happen at exactly the same parameters every time. That is the chaotic nature of a rotor system. We pilots understand this.
If a tiltrotor aircraft enters VRS, there is no guarantee that both proprotors will go into it at the same time...or even that both of them will. The prospect of only one proprotor entering VRS at low altitude is horrifying. If the pilot does not immediately recognize that one proprotor is on the edge of VRS (as happened to Majors Brow and Gruber that night in Marana), his instinctive, natural reaction will be to counter any roll excursions with opposite stick, increasing the pitch of the down-going proprotor - just the exact wrong it needs.
Now maybe I'm totally wrong and it wasn't A-VRS at all. Whatever was the true cause of the Marana crash, it is clear that the V-22's roll rate exceeded the ability of the pilots to control it that fateful night. They were decellerating and decending...had the nose up and the nacelles tilted aft. Suddenly it rolled over and dove for the ground. Inexplicable, "one in a million" type of accident? Maybe. Let us hope so. But the fact that it happened once should tell us that it will happen again. Pilots sometimes do dumb things, no matter how many rules, guidelines, limitations and/or procedures are put in place to guard against them. Or maybe they're just inexperienced, or have low make/model time. Whatever. Don't believe me? Check out YouTube. Type in "Aircraft Crashes" to the search field.
I'm sure that all of the people working on the V-22 program have a lot of themselves invested in it. I'm sure they feel very emotionally involved, and take criticism of the aircraft personally. I'm also sure it's an exciting, fun aircraft to fly. Its capabilities are awesome.
But critics need not be expert V-22 pilots to comment on the design. And the critics have to ask, "As fantastic a flying machine as it is, do we really need this thing as a combat aircraft?"
Now me, I won't comment on the fact that after all this time the V-22 still doesn't have a gun. Maybe the Marines will be clairvoyant enough to know that every LZ they send the aircraft to will be enemy-free with no possibility of hostile fire. Let's hope so!
And me, I won't comment on the NAVAIR website figure that the HOGE altitude limit is a mere 5,000 feet. I guess the Marines and Air Force only plan to use the V-22 in relatively low altitude, desert-type scenarios. Let's hope all future wars are held at sea level.
And come to think of it, what altitude is considered "HOGE" for the V-22? How high can it hover and still be IGE? I would imagine/guess that every landing will involve at least some OGE time. Or maybe not, who knows what techniques they'll use when push comes to shove?
I really hadn't planned on commenting on the V-22. But some of its performance characteristics are relevant to the 609. Plus, I just don't think that people should be barred from saying anything about it simply because they haven't flown it. It's not a magic machine. It's an aircraft, plain and simple. Sure, it's an aircraft with some unique capabilities. How it will be used, and how well it will do in those uses are still in question, if not in doubt.
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It's beginning to look like the next-generation JHL will also be a tilt. The 'One-JHL' reference design selected by the JIPT to represent the platform in wargames bears a strong resemblance to Abe Karem's OSTR offering, and listening to the staffers it's clear that the DoD is heavily focused on speed, which may well favor the OSTR and QTR over the ATRH and X2.
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John,
it was this quote I was referring to: "Sometime ago Nick Lappos offered some thoughts about whether the Marana crash was VRS or in reality quite a different aerodynamic situation".
I entirely agree with you that the parameters you refer to are not going to cause VRS in a modern machine, and in general I think it is used to 'blame' all manner of mishandling.
it was this quote I was referring to: "Sometime ago Nick Lappos offered some thoughts about whether the Marana crash was VRS or in reality quite a different aerodynamic situation".
I entirely agree with you that the parameters you refer to are not going to cause VRS in a modern machine, and in general I think it is used to 'blame' all manner of mishandling.
Macrave,
Back in post six of this thread where I listed the link to the articles....I said this.....
Are you so sensitive to any criticism of the V-22 that you can not take the time to read and consider "all" that was said?
Being a tax payer...I certainly have the right to question how my Tax dollars get spent.
The fact I consider the V-22 to be a complete waste of our hard earned dollars due to the cost alone.....just as the waste of money on the Harrier year after year....is my opinon and as such is just as valid as any other opinion.
I would suggest the lives of our Marines hold way too much value to be lost in training missions that could wait until the machine is fully tested and cleared for operational testing. It is no mean feat for the Mudders to run off and run onto an aircraft in the dark.....sandbags would be much cheaper than Marines if one was merely trying to achieve a certain weight for those tests.
It sounds to me that someone way up the food chain has bought into this concept and by God it is gonna fly....no matter what we have to do and no matter how we have to ignore the obivious.
Simple question....how does a Huey Cobra provide escort to a flight of V-22's?
Does the Marine Corps think that mission will now justify the Harrier?
I would suggest the Marines would be much better served to buy more 53's and even Blackhawks than waste all this money on V-22's that cost way more than the helicopters that would replace it.
Prove to me wrong and I will eat my Go Army-Beat Navy ball cap in front of an Evening Parade at Eighth and I.
Back in post six of this thread where I listed the link to the articles....I said this.....
Within the article are links to additional articles that pertain to the discussion of tilt rotors.....each reader is left to their own to determine the validity of the arguments set forth.
Are you so sensitive to any criticism of the V-22 that you can not take the time to read and consider "all" that was said?
Being a tax payer...I certainly have the right to question how my Tax dollars get spent.
The fact I consider the V-22 to be a complete waste of our hard earned dollars due to the cost alone.....just as the waste of money on the Harrier year after year....is my opinon and as such is just as valid as any other opinion.
I would suggest the lives of our Marines hold way too much value to be lost in training missions that could wait until the machine is fully tested and cleared for operational testing. It is no mean feat for the Mudders to run off and run onto an aircraft in the dark.....sandbags would be much cheaper than Marines if one was merely trying to achieve a certain weight for those tests.
It sounds to me that someone way up the food chain has bought into this concept and by God it is gonna fly....no matter what we have to do and no matter how we have to ignore the obivious.
Simple question....how does a Huey Cobra provide escort to a flight of V-22's?
Does the Marine Corps think that mission will now justify the Harrier?
I would suggest the Marines would be much better served to buy more 53's and even Blackhawks than waste all this money on V-22's that cost way more than the helicopters that would replace it.
Prove to me wrong and I will eat my Go Army-Beat Navy ball cap in front of an Evening Parade at Eighth and I.
Thread Starter
Far be it for me to try to drag us back to the thread, but the V-22 is one thing - a civil tilt rotor is another.
Is a civil tilt rotor's role like Dan Reno's characterisation of the USAF mission - and therefore likely to succeed, or are the potential handling/safety issues so intractable that it will fail?
Is a civil tilt rotor's role like Dan Reno's characterisation of the USAF mission - and therefore likely to succeed, or are the potential handling/safety issues so intractable that it will fail?
I think the civil tiltrotor's success/failure will ultimately come down to $$$$--purchase price and operating/mx costs. There will be issues, and probably some bent metal, but the basic tiltrotor design has been flying since the 1950s. Any word on what Bell-Agusta is currently asking for the BA609?