V-22 can't autorotate. Say what?
Avoid imitations
Join Date: Nov 2000
Location: Wandering the FIR and cyberspace often at highly unsociable times
Posts: 14,591
Received 448 Likes
on
237 Posts
Yes, unless I have been flying under a total misaprehension these last thirty years, I think someone is confusing the control names.
Join Date: Apr 2004
Location: A galaxy far far away
Posts: 109
Likes: 0
Received 0 Likes
on
0 Posts
A more complete explanation, also covering V22 survivability in general:
http://www.globalsecurity.org/milita...22-survive.htm
An excellent site.
http://www.globalsecurity.org/milita...22-survive.htm
An excellent site.
Avoid imitations
Join Date: Nov 2000
Location: Wandering the FIR and cyberspace often at highly unsociable times
Posts: 14,591
Received 448 Likes
on
237 Posts
Yes, but it over-hypes the advantages of the tilt rotor over the helicopter. Most of the the so-called advantages also apply to helicopters.
Helicopters can also be flown at altitudes where small arms fire is a tiny threat. The SA threat becomes almost negligable at surprisingly low altitudes.
Helicopters can also be given full anti-ice / de-icing protection. The Norwegian Super Pumas flying the North sea have been so equipped for over twenty years.
The tilt rotor will NEVER truly replace the helicopter, except in some specialised (or heavily politically sensitive) roles. It is a specialised aircraft, trading lifting power and low speed handling ability for the "Holy Grail" of a higher cruise speed.
Helicopters can also be flown at altitudes where small arms fire is a tiny threat. The SA threat becomes almost negligable at surprisingly low altitudes.
Helicopters can also be given full anti-ice / de-icing protection. The Norwegian Super Pumas flying the North sea have been so equipped for over twenty years.
The tilt rotor will NEVER truly replace the helicopter, except in some specialised (or heavily politically sensitive) roles. It is a specialised aircraft, trading lifting power and low speed handling ability for the "Holy Grail" of a higher cruise speed.
Thread Starter
Join Date: Dec 2004
Location: USA
Age: 55
Posts: 305
Likes: 0
Received 0 Likes
on
0 Posts
ShyTorque, Spruit's attempt at 'educating' you was downright hilarious! Do they have any idea who you are?
I agree with your point; the tiltrotor concept is in some ways like the autogyro: a courageous attempt at combining the best of a helicopter with the best of an airplane. Sadly, it ends up a compilation of the worst traits of the two modes of flight. Makes you wonder how Bell/Agusta is going to do with their 609. At least it will be able to autorotate. The FAA would never be as cavalier as the Pentagon has been in waiving that requirement. Or would they?
What does the V-22 exactly give the Marines? Speed? Range? Over a short range the Osprey's speed advantage over a helicopter is negligible. And why would they need long range? We're not fighting the USSR anymore. There's got to be a secure airfield within a hundred miles or so of any battlefied, where Marines can get out of a plane and into a helicopter for the last leg of the journey. Nobody likes airport layovers but c'mon...
I agree with your point; the tiltrotor concept is in some ways like the autogyro: a courageous attempt at combining the best of a helicopter with the best of an airplane. Sadly, it ends up a compilation of the worst traits of the two modes of flight. Makes you wonder how Bell/Agusta is going to do with their 609. At least it will be able to autorotate. The FAA would never be as cavalier as the Pentagon has been in waiving that requirement. Or would they?
What does the V-22 exactly give the Marines? Speed? Range? Over a short range the Osprey's speed advantage over a helicopter is negligible. And why would they need long range? We're not fighting the USSR anymore. There's got to be a secure airfield within a hundred miles or so of any battlefied, where Marines can get out of a plane and into a helicopter for the last leg of the journey. Nobody likes airport layovers but c'mon...
Avoid imitations
Join Date: Nov 2000
Location: Wandering the FIR and cyberspace often at highly unsociable times
Posts: 14,591
Received 448 Likes
on
237 Posts
Revolutionary, No matter, I'm only a mere pilot but I've been around for a while; as a pre-flight I do have a look at what folks have on their profile.
I'm still intrigued by the theory that pushing a collective forward gets a helicopter out of VRS. If there's enough adrenaline around, this might result in something interesting - like the grip end of the collective being pushed off.
I'm still intrigued by the theory that pushing a collective forward gets a helicopter out of VRS. If there's enough adrenaline around, this might result in something interesting - like the grip end of the collective being pushed off.
Subscribe to OTH warfare and you will understand the importance of the tiltrotor to my brother Marines. The aircraft is going to have further teething problems no doubt, but the concept (if not the aircraft) is a strategic leap in warfare.
Another area is NEO operations. Study even just a bit about the embassy evacuation in Somalia in 1991. The mission was accomplished, despite the equipment available, not because of it.
Even in short range operations there is a large advantage to faster, more capable aircraft. A few minutes may not seem much to an armchair quarterback, but could be the difference between life and death to a grunt in a firefight.
Another area is NEO operations. Study even just a bit about the embassy evacuation in Somalia in 1991. The mission was accomplished, despite the equipment available, not because of it.
Even in short range operations there is a large advantage to faster, more capable aircraft. A few minutes may not seem much to an armchair quarterback, but could be the difference between life and death to a grunt in a firefight.
Gents,
The reason why the USMC is so wedded to the concept of the tiltrotor is indeed range. Not in the traditional sense of invading the USSR, but due to the new "Visions" of Sea Basing and Ship-To-Objective-Manoeuvre (STOM). This argues that, rather than conventional amphib doctrine where you assault a coast, build up combat pwr then strike inland to the enemy centres of gravity you simply fly, direct, to the CoG - thus, the arguement goes, providing shock, dislocation and denial of manoeuvre to the enemy (now removing doctrine bulls**t book from ars*). To go 200 miles plus inland from over the horizon offshore requires a fast(ish), survivable (yet to be proved in the V-22's case) aircraft with good range, hence V-22. But, to deliver the same combat effect in one wave as a Sqn of Ch-53s you're going to need an awful lot of them, or launch the -53s a long time before the V-22s and RV at the IP..
Shytorque, you clearly need to be less subtle in your banter.....
The reason why the USMC is so wedded to the concept of the tiltrotor is indeed range. Not in the traditional sense of invading the USSR, but due to the new "Visions" of Sea Basing and Ship-To-Objective-Manoeuvre (STOM). This argues that, rather than conventional amphib doctrine where you assault a coast, build up combat pwr then strike inland to the enemy centres of gravity you simply fly, direct, to the CoG - thus, the arguement goes, providing shock, dislocation and denial of manoeuvre to the enemy (now removing doctrine bulls**t book from ars*). To go 200 miles plus inland from over the horizon offshore requires a fast(ish), survivable (yet to be proved in the V-22's case) aircraft with good range, hence V-22. But, to deliver the same combat effect in one wave as a Sqn of Ch-53s you're going to need an awful lot of them, or launch the -53s a long time before the V-22s and RV at the IP..
Shytorque, you clearly need to be less subtle in your banter.....
Join Date: Oct 2002
Location: 1 Dunghill Mansions, Putney
Posts: 1,797
Likes: 0
Received 1 Like
on
1 Post
According to a recent whitespace Bell/Boeing presentation, the current recommended solution for 'busting out' of VRS is to apply 2° nacelle tilt using the maximum (=normal) rate of conversion. IIRC, this results in 400–500ft altitude loss. The V-22 is susceptible to entering VRS at descent speeds between 2000-5000fpm and airspeeds up to 40kt.
Not all the way forward to 0°, since this would result in proprotor ground strike. The civil BA609 shares the same drawback.
I/C
Originally Posted by WEBF
Can't the V22 put the rotors forward (as in forward flight) and land like a STOL aircraft in an emergency?
I/C
Join Date: Jan 2002
Location: The front end and about 50ft up
Posts: 510
Likes: 0
Received 0 Likes
on
0 Posts
Low Observable:
Well I gave a recent example of an autorotation and engine off landing in a twin engine rotary. Your 757 does have a 2 engine out mode - it's called gliding - and it has been useed in anger on large commercial twin jets in recent times. Two examples off the top of my head would be the Airbus the glided about 200 miles into the Azores and the hijacked Ethiopian 767 that ditched off the Comores after running out of fuel.
The point is that double engine failures do occur, often for unpredictable reasons. To design an aircraft that, to use a media term, falls out of the sky following a double engine failure seems unwise to me. Many people owe their lives to the fact that most fixed wing and rotary aircraft can be placed on the ground with a good chance of success following the failure of all engines.
Can someone explain why you'd need to autorotate in a twin-engine aircraft? After all, the 757 that I took from LGW to EWR the other day doesn't have an official two-engine-out mode.
The point is that double engine failures do occur, often for unpredictable reasons. To design an aircraft that, to use a media term, falls out of the sky following a double engine failure seems unwise to me. Many people owe their lives to the fact that most fixed wing and rotary aircraft can be placed on the ground with a good chance of success following the failure of all engines.
Below the Glidepath - not correcting
The V-22 has been evaluated by people who know how helicopters work and hence measure its performance against that. A bit like the British Army's initial evaluation of the Tank by Cavalry officers in 1916. The V-22's eventual operational performance will either save it or kill it.
Join Date: Aug 2003
Location: Sale, Australia
Age: 80
Posts: 3,832
Likes: 0
Received 0 Likes
on
0 Posts
Anyone with an interest in the civil requirements for the tilt rotor (Bell 609) will find details here http://www.faa.gov/aircraft/draft_do...rt%20basis.doc
Thread Starter
Join Date: Dec 2004
Location: USA
Age: 55
Posts: 305
Likes: 0
Received 0 Likes
on
0 Posts
ShyTorque, if pushing the collective forward doesn't get you out of VRS I suppose you could always get out and push the helicopter forward, no?
Evalu8ter, you clearly have a very sophisticated understanding of the modern battlefield (I myself have none) and I can see now where the V-22 would come in handy. Having said that, as Fg Off Max Stout points out, double engine failures do occur. I just cannot understand how the Pentagon could go forward with an aircraft (one meant to carry a whole complement of troops no less) that is unable to deal with this particular emergency. Is it just a waiting game now to see when the first V-22 malfunctions spectacularly?
Evalu8ter, you clearly have a very sophisticated understanding of the modern battlefield (I myself have none) and I can see now where the V-22 would come in handy. Having said that, as Fg Off Max Stout points out, double engine failures do occur. I just cannot understand how the Pentagon could go forward with an aircraft (one meant to carry a whole complement of troops no less) that is unable to deal with this particular emergency. Is it just a waiting game now to see when the first V-22 malfunctions spectacularly?
Join Date: Feb 2005
Location: NW FL
Posts: 230
Likes: 0
Received 0 Likes
on
0 Posts
You need sinkrates in excess of 1600-1800fpm to enter VRS in V-22. Most aproaches end up with no more than 400fpm sink/flare. At roughly 1000fpm, bitching betty comes on & yells, "sink rate" - should you choose to ignore it, & find yourself entering VRS, a 3-second application of Forward Nacelle & add power to fly out of it results in virtually no altitude loss.
One of the early V-22 crashes resulted because the test pilot kept resetting his master reset & eventually bled all his hydraulics away. The computer analyzes & contains hydraulic leaks through a protocal, but when master reset is iniated, it assumes all is well & must run through the protocal again.
Many of the small problems that are supposed to crop up during DT&E and OT&E have done - the overwhelming majority of them have been fixed.
My understanding of the autorotate deal was compromise. Original design for rotors was actually much larger diameter & sufficient energy was stored in them. In order to accomodate shipborne ops & folding blades, the size was reduced to the point autorotation was ineffective.
Current single engine safe speed is roughly 40-50kts, so you're going to "roll on" (shattering your rotors when you do) with 25-30+ knots of forward airspeed. That's emminently survivable on a hard surface - not so much on an unprepared surface - particularly with a top-heavy beast like the Osprey (probably a lot of tumbling).
Single engine failure in most helos results in arriving at the scene of landing - it merely cushions the autorotation. The same is true of the Osprey. Dual engine failure requires that forward airspeed mentioned in paragraph above.
The Osprey is not, nor was it ever, a helo replacement. It is a different animal entirely. Many USAF brass view it as a Pave Low replacement - it isn't. But those are political problems, not aircraft problems...
One of the early V-22 crashes resulted because the test pilot kept resetting his master reset & eventually bled all his hydraulics away. The computer analyzes & contains hydraulic leaks through a protocal, but when master reset is iniated, it assumes all is well & must run through the protocal again.
Many of the small problems that are supposed to crop up during DT&E and OT&E have done - the overwhelming majority of them have been fixed.
My understanding of the autorotate deal was compromise. Original design for rotors was actually much larger diameter & sufficient energy was stored in them. In order to accomodate shipborne ops & folding blades, the size was reduced to the point autorotation was ineffective.
Current single engine safe speed is roughly 40-50kts, so you're going to "roll on" (shattering your rotors when you do) with 25-30+ knots of forward airspeed. That's emminently survivable on a hard surface - not so much on an unprepared surface - particularly with a top-heavy beast like the Osprey (probably a lot of tumbling).
Single engine failure in most helos results in arriving at the scene of landing - it merely cushions the autorotation. The same is true of the Osprey. Dual engine failure requires that forward airspeed mentioned in paragraph above.
The Osprey is not, nor was it ever, a helo replacement. It is a different animal entirely. Many USAF brass view it as a Pave Low replacement - it isn't. But those are political problems, not aircraft problems...
"The Osprey is not, nor was it ever, a helo replacement"
Herk
For the USAF or the USMC? If the later, I might have to disagree. The -46 is long in the tooth. Been a number of years since I've been on one, but the Vietnam bullet hole patches were plentiful. If you're talking about a leap in capabilities far beyond a simple one for one replacement with a newer generation helo, then yes.
One thing you didn't mention in the debate over the lead service was the number of times the program was almost killed by the DoD. Then SecDef Cheney tried on many occasions to end it all. Finally after some open warfare within congress quietly led by Marines operatives Cheney relented. To paraphrase him, "OK, just don't shove them down my throat" The Marines enjoy a tremendous reputation within the beltway, I don't know if the USAF would have the political clout to pull off the mission given the tenuous situation it was having with procurement.
One could also argue, the Marines have as much experience as any of the services in introducing vertical lift in to the inventory.
Herk
For the USAF or the USMC? If the later, I might have to disagree. The -46 is long in the tooth. Been a number of years since I've been on one, but the Vietnam bullet hole patches were plentiful. If you're talking about a leap in capabilities far beyond a simple one for one replacement with a newer generation helo, then yes.
One thing you didn't mention in the debate over the lead service was the number of times the program was almost killed by the DoD. Then SecDef Cheney tried on many occasions to end it all. Finally after some open warfare within congress quietly led by Marines operatives Cheney relented. To paraphrase him, "OK, just don't shove them down my throat" The Marines enjoy a tremendous reputation within the beltway, I don't know if the USAF would have the political clout to pull off the mission given the tenuous situation it was having with procurement.
One could also argue, the Marines have as much experience as any of the services in introducing vertical lift in to the inventory.
Thread Starter
Join Date: Dec 2004
Location: USA
Age: 55
Posts: 305
Likes: 0
Received 0 Likes
on
0 Posts
US Herk, "Dual engine failure requires that forward airspeed mentioned in paragraph above". Do you mean the 40-50 knots? So the h/v curve isn't so big after all? To be sure I understand: let's say you're at 1,500 feet and 100 kts with nacelles up in helicopter mode and at that moment both engines decide to quit. What happens next?
Cyclic, collective, schmollective... Jeebus, can't a guy make a mistake? I had been out picking beets on the Agricultural Cooperative No. 541 "V.I. Lenin" and the word was on my mind.
Join Date: Feb 2005
Location: NW FL
Posts: 230
Likes: 0
Received 0 Likes
on
0 Posts
For the USAF or the USMC? If the later, I might have to disagree. The -46 is long in the tooth.
It's not a helicopter. Period. End of discussion.
People want to put things in nice neat boxes. Well, there's a new box to put stuff in - tiltrotor.
Yes, the USMC wants to replace the CH-46 because they're old. They bought the Osprey. It will do the -46 mission, but that doesn't mean it's a -46 replacement.
Too much semantics? Perhaps.
Same with AFSOC.
If someone wants heavy rotary lift, buy Chinook.
let's say you're at 1,500 feet and 100 kts with nacelles up in helicopter mode and at that moment both engines decide to quit. What happens next?
Most of the approaches occur low & fast with a near immediate stop. There is no long straight down hover. It will terrain-follow in at 100' & 220+ kts, enter approach mode & take a 4* glidepath down to 50'/0kts. If it all goes pearshaped at 50', well, that's how far you fall. A lot of pure helos will hurt themselves from 50' w/no forward velocity as well - simply not a lot of energy stored in the rotors.
Once again, I'm not an Osprey pilot. But we do have a program here where I can fly it - I'm trying to get my stuff in one sock so I can do so.
