What's the latest news of the V22 Osprey?
Join Date: Apr 2003
Location: Vancouver, BC, Canada
Posts: 1,635
Likes: 0
Received 0 Likes
on
0 Posts
Look, we must face the fact that the technology that allows the V-22 to exist simply has not been developed yet.
The obvious problem is that the V-22 is a compromise between the helicopter and the airplane. It can never have the efficiency of a helicopter in hover (vertical thrust) because its disk areas are too small for low disk loading, and, it can never have the efficiency of an airplane (horizontal thrust) because its disk areas are too large for working with high velocity free-air.
Sikorsky has approximately a dozen patents covering 'Variable Diameter Tiltrotor'. However, it appears that the complexity of physically changing the length of the blades has been its handicap.
There have been a few other ideas over the years but every one is subjected to a common limitation. That being; all of mankind's successful developments are extensions of nature and nature has only provided examples of rotating airfoils that move axially in their environment.
Perhaps the AeroVantage with its aerodynamic 2:1 change in disk area might be the answer. And, it is openly and freely available for any company, institution, university, or RC hobbyist to build and develop.
Dave
So let me get this straight, the tiltrotor concept is "fundamentally flawed" because it does not simultaneously outperform a helicopter in hover and a fixed wing in cruise?
Has anyone ever argued that a tiltrotor is NOT a compromise between the performance of the two? This is pretty tired old strawman. Its not as if it CAN'T hover, or that it ISN'T absolutely faster than any helicopter.
And with the newest bloomberg report, where is this "53%" data coming from???
March 2011
While the availability rate of the Osprey in the field has remained constant at just under 72 percent, the Marine Corps would like to see 75 percent across the board.
Feb 2011
Readiness rates for the Marine version are around 70 percent, which is quite respectable for a new and novel airframe.
Has anyone ever argued that a tiltrotor is NOT a compromise between the performance of the two? This is pretty tired old strawman. Its not as if it CAN'T hover, or that it ISN'T absolutely faster than any helicopter.
And with the newest bloomberg report, where is this "53%" data coming from???
March 2011
While the availability rate of the Osprey in the field has remained constant at just under 72 percent, the Marine Corps would like to see 75 percent across the board.
Feb 2011
Readiness rates for the Marine version are around 70 percent, which is quite respectable for a new and novel airframe.
Join Date: Aug 2010
Location: here
Posts: 93
Likes: 0
Received 0 Likes
on
0 Posts
Might I point out that the quote has two parts to it:
considers fleet wide data which is probably similar to the numbers from the early 2011 articles.
considers data from a few, maybe even one aircraft. Was the non availability from mechanical issues, instrumentation, weather (did it have test instrumentation that made it a dry aircraft?), issuse with the new software, etc. There are many reasons why a test aircraft may not be available when a fleet aircraft would be. There is not enough information in the article to draw a conclusion either way. To do so is pure speculation.
Across the fleet, the V-22 generally meets reliability and maintainability requirements"
Still, the V-22 in its most recent testing was available only 53 percent of the time it was required
SansAnhedral:
No, that's not the reason the tiltrotor/tiltengine concept and design is fundamentally flawed. If you do not understand why, then you do not understand much about helicopters. Sorry.
So let me get this straight, the tiltrotor concept is "fundamentally flawed" because it does not simultaneously outperform a helicopter in hover and a fixed wing in cruise?
No, that's not the reason the tiltrotor/tiltengine concept and design is fundamentally flawed. If you do not understand why, then you do not understand much about helicopters. Sorry.
Perhaps you also think the single rotor helicopter is "fatally flawed" as well due to LTE?
Or maybe the under slung teetering rotor is "fatally flawed" due to mast bumping?
I'm seeing a constant thread here.
I think its you, sir, who may be lacking in helicopter understanding.
Sans,
Hopefully, you will recall the "LTE" you reference is a Bell Helicopter alibi they use to explain putting too small a tail rotor on their helicopters. Other Single Rotor designs do not have that problem thus applying that to all Single Rotor helicopters is not really valid.
Anyone who has flown several different models of Bell's understands this....especially when also having the benefit of flying things built by Sikorsky.
Sikorsky understands tail rotors.....Bell surely doesn't.
Oh....hang on a mo'....Bell Engineering....a common trait between the LTE and other aerodynamic issues extant. Surprise...surprise!
Perhaps you also think the single rotor helicopter is "fatally flawed" as well due to LTE?
Anyone who has flown several different models of Bell's understands this....especially when also having the benefit of flying things built by Sikorsky.
Sikorsky understands tail rotors.....Bell surely doesn't.
Oh....hang on a mo'....Bell Engineering....a common trait between the LTE and other aerodynamic issues extant. Surprise...surprise!
Join Date: Oct 2002
Location: 1 Dunghill Mansions, Putney
Posts: 1,797
Likes: 0
Received 1 Like
on
1 Post
Originally Posted by jeffg
There are many reasons why a test aircraft may not be available when a fleet aircraft would be. There is not enough information in the article to draw a conclusion either way.
I/C
SAS your prejudice is showing through, as if it wasn't enough you hammer on Bell in roughly every-other thread.
To claim LTE is a Bell-specific phenomenon is frankly laughable. One could argue all day it is apparent in MOST small gross weight helicopters, and with the sheer numbers of 206s flying around, your judgement is a bit skewed from anecdotes.
Ah here is an old post/thread talking about B206, Enstroms, Hughes etc
http://www.pprune.org/rotorheads/756...tml#post720544
Other Single Rotor designs do not have that problem thus applying that to all Single Rotor helicopters is not really valid
Ah here is an old post/thread talking about B206, Enstroms, Hughes etc
http://www.pprune.org/rotorheads/756...tml#post720544
India sizes up V-22 Osprey
India sizes up V-22 Osprey
Print
By: GREG WALDRON SINGAPORE 6 hours ago Source:
India has shown interest in the Bell Boeing V-22 Osprey, although it has not stated a formal requirement for the tiltrotor aircraft.
Boeing confirmed that it was "invited in-country to provide more information" on the V-22, but that it has not received "an official, written [request for information] from India".
In addition, Indian officials visited the V-22 aircraft during the Dubai air show in November 2011, where they asked questions about the aircraft.
The V-22 would be well suited to operations along India's vast Himalayan frontier, where high altitudes and long distances hinder helicopter operations.
At last year's Paris and Dubai air shows, Osprey representatives made much of a mountain rescue mission in June 2010 conducted by two US Air Force CV-22s. The aircraft flew a 1,290km (700nm) round-trip at 15,000ft (4,570m), landed amid mountainous terrain in dust storm conditions, collected 32 personnel and returned to base.
In response to a query about whether the V-22 could be fitted with a radar array for use on Indian aircraft carriers, Boeing said: "While AEW&C [airborne early warning and control] has been identified as a future mission well suited to the Osprey's performance profile and specifications, it is not a mission performed by current customers and it would be premature to speculate on what specific equipment would be utilised for that mission."
In 2010, the Indian navy requested information from Northrop Grumman on the E-2D Hawkeye AEW&C aircraft, which is capable of operating from aircraft carriers using steam catapults. This aircraft may not be suitable for current and planned Indian carriers, which rely on "ski-ramps" to launch aircraft. This restricts them to using airborne early warning helicopters, which are far less capable than their fixed-wing counterparts.
By: GREG WALDRON SINGAPORE 6 hours ago Source:
India has shown interest in the Bell Boeing V-22 Osprey, although it has not stated a formal requirement for the tiltrotor aircraft.
Boeing confirmed that it was "invited in-country to provide more information" on the V-22, but that it has not received "an official, written [request for information] from India".
In addition, Indian officials visited the V-22 aircraft during the Dubai air show in November 2011, where they asked questions about the aircraft.
The V-22 would be well suited to operations along India's vast Himalayan frontier, where high altitudes and long distances hinder helicopter operations.
At last year's Paris and Dubai air shows, Osprey representatives made much of a mountain rescue mission in June 2010 conducted by two US Air Force CV-22s. The aircraft flew a 1,290km (700nm) round-trip at 15,000ft (4,570m), landed amid mountainous terrain in dust storm conditions, collected 32 personnel and returned to base.
In response to a query about whether the V-22 could be fitted with a radar array for use on Indian aircraft carriers, Boeing said: "While AEW&C [airborne early warning and control] has been identified as a future mission well suited to the Osprey's performance profile and specifications, it is not a mission performed by current customers and it would be premature to speculate on what specific equipment would be utilised for that mission."
In 2010, the Indian navy requested information from Northrop Grumman on the E-2D Hawkeye AEW&C aircraft, which is capable of operating from aircraft carriers using steam catapults. This aircraft may not be suitable for current and planned Indian carriers, which rely on "ski-ramps" to launch aircraft. This restricts them to using airborne early warning helicopters, which are far less capable than their fixed-wing counterparts.
SASless, LTE was experienced in the SH-2F in certain shipboard landing configurations, and IIRC, SH-60B was susceptible to it at high GW and hot/heavy/cross wind conditions. (Been a few years since that nut roll in the safety meetings ...)
I can't recall at the moment whether or not the SH-2F problem came from wind to left or right, but I seem to recall the SH-60 risk as coming from significant left cross wind ... but I may be confusing the two in my memory. Seahawk was far less likely to encounter that problem.
You could lose TR effectiveness boost off, but that's a different story ...
Sans to FH1100:
Ya think? 
I can't recall at the moment whether or not the SH-2F problem came from wind to left or right, but I seem to recall the SH-60 risk as coming from significant left cross wind ... but I may be confusing the two in my memory. Seahawk was far less likely to encounter that problem.
You could lose TR effectiveness boost off, but that's a different story ...
Sans to FH1100:
I think its you, sir, who may be lacking in helicopter understanding.
H-60 LTE
Glad of the post of the UH-60 snow roll, as it provides an excellent point of departure, one which applies to both S-70 models.
There have been a few cases where pilots have reported running out of left pedal. The above video is one. In each of the cases of which we are aware, however, the ship has been in a situation where the pilot has increased collective to the point, and beyond the point, at which the engine TGT limiter has been reached. The Nr has drooped, and the tail rotor thrust has decreased as the square of the Nr droop ( lift is a velocity squared function ), but with the engine on the limiter, the torque will still rise with that increased collective which caused the Nr droop. Thus the pilot, attempting to hover in a situation where there is insufficient power to do so in the first place, can droop the Nr enough to create a shortage of tail rotor thrust. The relative wind can be an influence, for good or for bad, on this situation, as it influences the magnitude of tail rotor thrust required.
Hope this clarifies the subject a bit. Bottom line: the ship is outside the flight envelope.
Thanks,
John Dixson
There have been a few cases where pilots have reported running out of left pedal. The above video is one. In each of the cases of which we are aware, however, the ship has been in a situation where the pilot has increased collective to the point, and beyond the point, at which the engine TGT limiter has been reached. The Nr has drooped, and the tail rotor thrust has decreased as the square of the Nr droop ( lift is a velocity squared function ), but with the engine on the limiter, the torque will still rise with that increased collective which caused the Nr droop. Thus the pilot, attempting to hover in a situation where there is insufficient power to do so in the first place, can droop the Nr enough to create a shortage of tail rotor thrust. The relative wind can be an influence, for good or for bad, on this situation, as it influences the magnitude of tail rotor thrust required.
Hope this clarifies the subject a bit. Bottom line: the ship is outside the flight envelope.
Thanks,
John Dixson
Yes there are lots of 206's flying around...and everyone of them has the same potential of LTE....the fact Bell mod'ed the L series with the more powerful TR proves the point.
Anyone that flew the Huey in Vietnam understands planning for a takeoff path that curves to the right...and remembers the number 5800....as being the point you can droop the Engine RPM to...and still fly away....with a turn to the right.
The Sikorsky S-58T had a "Tail Rotor Buzz" warning...but that was about airflow and vibration....not loss of effectiveness unless the tail rotor shucked bits.
I have flown the 500C, D, E....and never ran out of Tail Rotor....also the 58T and 76....again plenty of TR, the Alouette III....yards of TR.....the BO/BK...never a hint of lack of TR. But...in the 204,205, and 206 series of helicopters....have encountered LTE.
I beat up on Bell whenever it is appropriate....as their engineering department has never been known for its inventiveness. They copied the Bell 47 into many different versions....but the same concept. It works....works fine....but it does have its limitations.
I love the Huey....anyone that has flown the old thing usually does as it is a good and reliable helicopter. The 206 is reliable.
But....LTE in Bell's is real....and not just when you droop the Nr!
Anyone that flew the Huey in Vietnam understands planning for a takeoff path that curves to the right...and remembers the number 5800....as being the point you can droop the Engine RPM to...and still fly away....with a turn to the right.
The Sikorsky S-58T had a "Tail Rotor Buzz" warning...but that was about airflow and vibration....not loss of effectiveness unless the tail rotor shucked bits.
I have flown the 500C, D, E....and never ran out of Tail Rotor....also the 58T and 76....again plenty of TR, the Alouette III....yards of TR.....the BO/BK...never a hint of lack of TR. But...in the 204,205, and 206 series of helicopters....have encountered LTE.
I beat up on Bell whenever it is appropriate....as their engineering department has never been known for its inventiveness. They copied the Bell 47 into many different versions....but the same concept. It works....works fine....but it does have its limitations.
I love the Huey....anyone that has flown the old thing usually does as it is a good and reliable helicopter. The 206 is reliable.
But....LTE in Bell's is real....and not just when you droop the Nr!
I beat up on Bell whenever it is appropriate....as their engineering department has never been known for its inventiveness
Not quite sure what you expect? Whats so revolutionary about Agusta, Eurocopter, Sikorsky etc? Unlike Bell, the past few decades they have all dumped all their R&D money into conventional aircraft (as opposed to tiltrotors, as something like 15 yeas ago one of Bell's former CEOs claimed they were no longer and helicopter company and were instead a "tiltrotor company"), and they best things we have seen are basically iterations of 20-30 year old systems as well (including the X2, er I mean XH59C).
Sans,
Check out the sales performance of Bell versus Eurocopter....then tell me about how successful they are.
EC has been cleaning Bell's Clock!
They are not able to sell to the US Army for crying out loud!
Check out the sales performance of Bell versus Eurocopter....then tell me about how successful they are.
EC has been cleaning Bell's Clock!
They are not able to sell to the US Army for crying out loud!
And Frank Robinson is kicking the pants off of Eurocopter.
I dont see the connection.
You claim Bell engineering is lacking, and cite sales number to substantiate the claim. Did it occur to you that Bell may have been focusing their "substandard" technical expertise on tiltrotors and military programs (H-1) for the past 20 years? The army wants Hawks, which stems from decisions made 25 years ago when the procurement strategy went something like "its Sikorsky".
(Though the army does seem to like their Kiowas)
Theres argualby nothing more technically advanced in any current market civil Eurocopter that cannot also be found in a machine from a competing manufacturer. Its about making something profitable for an operator, and how often does that contain anything even remotely leading edge?
I dont see the connection.
You claim Bell engineering is lacking, and cite sales number to substantiate the claim. Did it occur to you that Bell may have been focusing their "substandard" technical expertise on tiltrotors and military programs (H-1) for the past 20 years? The army wants Hawks, which stems from decisions made 25 years ago when the procurement strategy went something like "its Sikorsky".
(Though the army does seem to like their Kiowas)
Theres argualby nothing more technically advanced in any current market civil Eurocopter that cannot also be found in a machine from a competing manufacturer. Its about making something profitable for an operator, and how often does that contain anything even remotely leading edge?
Join Date: Aug 2010
Location: here
Posts: 93
Likes: 0
Received 0 Likes
on
0 Posts
I beat up on Bell whenever it is appropriate....as their engineering department has never been known for its inventiveness. They copied the Bell 47 into many different versions....but the same concept. It works....works fine....but it does have its limitations.
If you take a close look at ECs biggest selling aircraft today, the Astar, it's essentially the same design as the 47 with some updates.
Please do explain the similarities you think they have in common?
Shall we start with the Rotor Head....blades....for a start.
This I want to hear!