"Obscene" is the right word for it. The worst part is the Marines Knew about it since June of 1999 and did nothing!!! (and it was found in all the other V-22s)Certainly sounds like a no brainer to me. I wonder if this problem is throughout ALL Marine aviation and not just this program.

Hopefully with the spotlight shining on them these days there will be a shake up from top to bottom. Looks like they'll have no choice!

hpdunn

Understand from your profile that you are (or were?) Congressional Liaison (aka briefer?).
Thank you for the kind words. If you have taken the time to read all the way through this thread, perhaps you should also look at these URLS - which are also pertinent.

http://www.pprune.org/ubb/NonCGI/For...ML/000405.html Marine Corps grounds ....

http://www.pprune.org/ubb/NonCGI/For...ML/000557.html (Another MV-22 lost)

http://www.pprune.org/ubb/NonCGI/For...ML/000658.html Marine V-22 Maint Fraud

http://www.pprune.org/ubb/NonCGI/For...ML/000328.html

http://www.pprune.org/ubb/NonCGI/For...ML/000000.html BA609

http://www.pprune.org/ubb/NonCGI/For...ML/000389.html Tiltrotor

My interest in the Osprey stems from a visit to the sim at New River some time ago now and contacts with those in the program (past and present), as well as a helo background. If you read through from the beginning, despite all the gay banter to the contrary, it must be obvious to you that I had an inside straight and that pretty much all of what I said has come to pass. I would even lay claim (see much earlier) to email conversation with John Farley (well-known Brit Harrier XTP) well before the Marana accident - that I couldn't figure out how they'd resolved the problem of vortex ring. The "revelation" on the page about the hyd chafing having been known about - that is not news. The derisory comments about the vibration-damping Quincke technology also now looks a bit silly. It takes quite a "rub" in so few flight hours for a titanium hyd line to be penetrated by some soft wiring insulation (i.e. assuming it wasn't eventually arcing).

If you'd like to send your contribution to [email protected] I can refer it to my mentors and give you a useful opinion. You are quite right that this program was hijacked by the vested interests who had so much to lose .... that they've even now got so much more to lose. Those who objected to the way the program was going were never in a position to influence its direction - but they certainly saw it coming and gave me the benefits of their insights.

Pinochy-Unc:
Hey… saw you on the street the other day and I really like that neat head gear. The tin foil hat is excellent- but I really like the antenna fashioned out of a hangar- nice touch. :)

Your right- we all knew you had the "inside straight" http://www.pprune.org/ubb/NonCGI/redface.gif
and boy... now that you mention it you've really done it again- I'm sure there's nothing better for stopping those chaffy wire bundles than a couple of good :)Quinke Valves!!! :)
Really makes a lot of sense :rolleyes:

And now that you have a fan, I notice your resume has done a 180. For your year of postings you never denied your lack of experience with tilt rotors. Now all of a sudden your the ultimate insider with full access to Pax River facilities. You must have re-tuned your antenna direction to beam in some new experience http://www.pprune.org/ubb/NonCGI/eek.gif

That Pinochy-nose is jumping out of our computer screens at us now. :)(remember PaPa Jepetto!!!) :)

[This message has been edited by HeliFlight (edited 13 April 2001).]

Scatterchat
Find a new occupation. By time a tiltrotor - other than the old demo that is used to show folks how well it works (about 1/3 size of V-22) you (and I ) will be to old to qualify.

When a member of the Blue Ribbon Panel reaches the conclusion that we will just have to ignore autorotation (because the rotor can't be made large enough-- because it is too large to operate on carrier decks)
acknowledging he was not aware the helicopters have been operating off carrier decks - with helos as large as H-53 --then the whole country of Blue Ribbon Panels is turning into a roll over.Try realestate??

Here is my wrapup after 6 mths of study/reveiew
=============================================
The V-22 Iron Triangle - stll alive.
hpd

The story moves on - and is a classical case of the Iron Triangle revisited.

Whenever the basic procedures are set aside or over-ridden by Congress, Industry and a selected Military element to be the front line Champions --right or wrong -- the system has a way of letting profits obscure realities.

The use of PAC funds - spread widely - creates Congressional pressures within the Administration which can force funding of a quickly thrown together funding program, and ignores the basic requiremnents for a cycle of design, development and testing to be done BEFORE everyone jumps on biard and claims success. \

10-15 years ago there were voices, steeped in history and experience who could not make their voices heard.

Forty to 50 years experience with aerodynamics and design had established basic ground rules for aircraft. For aircraft flying normally -- all propulsion systems were kept on centerline or as close as possible -- to avoid assymetric trust problems. For many years the need for larger rudders was used to off-set problems associated with the need for extra lateral control after an engine failure. It was fundamental, period.

At the same time, helicopter design was growing rapidly, reaching the current multiple applications and uses throughout the world. One of the fundamental design requirements was to design the rotors in such a way as to permit them to provide a capability following engine failures, to generate rotating kinetic energy by having the upward wind forces to drive the rotor as if it were 'gliding' similar to a wing on an aircraft.

This was called "autorotation" and was THE most important item in all training and testing for pilots when learning to operate a helicopter.

The design of helicopter rotors thus resulted in a relatively "low disk loading" design, which both allowed the rotors to operate in autorotation, and to build up lost energy by increasing the rotors speed in descent, which could then provide the required vertical thrust to make a safe landing after engine failure.

In the case of the V-22 design, several of the known design requirements were set aside in an attempt to design an aircraft which could be flown as a normal aircraft and as a helicopter. Past experience suggests that up to a certain size, e.g. the
XV-15, some compromises can be accomplished.

At some point, the increases in size, forces, thrust/propulsion and other design requirements get out of hand. The compromises to force designing (thru the use of multiple redundant computers, hydraulics, fly-by-wire) to reach a certain goal begins to produce results which were either not thought thru or were ignored.

First, in the case of normal flight, we have the V-22 with two 38 foot diameter "propellers" located at the two extreme wingtips. If you had never talked to a pilot or engineer familiar with multi engine aircraft, perhaps it would not have occurred to someone to expect that in windy, turbulent, gusty air -- or when encountering the turbulent airflow wake of another aircraft --- to expect the V-22 to react like any airplane -except much more so (the surface area of the V-22 propellers are perhaps ten times more than that of 'normal' propeller aircraft)-- and to try to roll itself over (without the pilots ability to react properly).

This is not only very scary, it is absolutely dangerous - and far outside normal design parameters for controlling gust loadings.

Next, we look at the propellers -- which in the case of the V-22 have cleverly been renamed 'rotors' -- and their use in the 'helicopter' mode. There are in fact significant differences.

A helicopter rotor blade is essentially a long fairly flexible wing. An aircraft propeller is on the other hand a fairly stiff or hard blade, with little or no flexibility.

For aerodynamic purposes, the rotor blade has a small amount of 'twist' - perhaps several (8-12) degrees.

The V-22 Propeller -as do most all normal aircraft - has a much higher 'twist' (perhaps 45-50 degrees) built into the propeller design, which permit them to operate more efficiently in staight and level flight and is related to the higher speeds of aircraft.

The compromise required for reaching the higher speeds fot the V-22 has come at an unbelievable cost. The propellers themselves are extrememly inefficient when acting like rotors in hovering.

The disk loading (the amount of lifting forces) required to hover the aircraft is on the order of Twice that of any comparable weight helicopter!!

This in turn, significantly REDUCES payload. In fact the V-22 is the only aircraft flying today whose empty weight is about 3/4 of its total gross weight. Most aircraft - including helicopters such as the H-53 - can carry their own weight!! The V-22 only about 1/3-1/4th!

The next result in this compromise of design, is that because of the high disk loading, the aircraft is NOT capable of safe autorotation - and in fact it is 'prohibited' in the USMC flight manual.

If you tell this to a thousand helicopter pilots - some with thousands of hours of experience - they will undoubtedly suggest you are either incorrect - or crazy (and will have little desire to try it out).

The designer response to this is that it is very unlikely to be needed. And -- they will tell you that the multi piece connecting tubes between the two engines will take care of the problem. Perhaps in may cases this may be true.

The reason it is not safe for autorotation is that the propeller design - with a very high twist angle (needed for forward flight) -- is not designed to and does NOT generate sufficient kinetic energy - thru propeller 'spin up' ,when descending in an unpowered condition.

Its basically has very little inertia when it stalls out and very little kinetic energy buildup capability. The patented contractor 'solution' is to start a descent or gliding descent if one engine fails, and to prepare to rotate the engine nacelles rearward when near a landing site (so that the two 38 ft diam propellers do not smash into the ground). Please note that the FAA and military require that an aircraftwith two engines should be allowed to continue safe flight upon single engine failure.

Finally we find that the high twist and high loading of the V-22 propellers, produce a phenomenon similar to - but far far more reaching than that of its sister helicopters.

Whereas helicopters can reach a point where they can "settle with power" if they try to lift to much - or fly too high. In the case of helicopters, the pilot can readily and easily 'fly out' of the settling condition using simple intuitive procedures which he is taught in initial training.

In the case of the V-22 Propellers in hover or approach/conversion modes, the initial airflow changes near the blade tips are essentially the same as for helicopters. As the 'settling' proceeds, the tip vortices on the propeller (twist and high loading) move rapidly inward and form what is now called a Vortex Ring State. At this point -usually on one propeller before the other, the aircraft losooses its controlability very rapidly - and can in a matter of a second or two invert and crash.

If a pilot does recognize and attempt to stop the rollover/tuck down - and tries to offset the uncommanded rollover -- he instinctively - and unfortunately - will do exactly the wrong thing!. It is fatal.

If one studies the costs of the tradeoffs made in force designing a system --(I call it forced designing because it requires the use special software and hardware to force a given goal -- even if the compromizes reduce the efficiencies and increase the risks of life -- at a higher cost) -- there are always several flaws to be found.

We have reached the point in engineering that we can literally do anything we want - even if it makes no sense and costs are out of sight.

Designing a control system which can get out of physical control faster than the computers trying (redundantly) to resolve and initiate changes - is in the end - a folly.

The Combat Military Perspective of the V-22.

Given the foregoing problems and tradeoffs required in the design of the V-22, we
should look at the results of this marvellous - but costly, inefficient and high risk aircraft as it applies to the Defense Department. A review of the DOTE, DOD/IG, GAO and other reports can be used to see the whole picture. The effort here will be to narrow down a few of the dozens of citations.

The V-22 has been touted by the Contractors, Congress and the USMC (in that order) as the most signifcant development in aviation history. Perhaps if more studies and reviews of similar attempts to compromise aerodynamics had been done, an entirely different approach might have been used - instead of the 'forced design' concept. As a military combat aircraft it is simply not, period.

A quick review - after 12+ years of flying and testing:

1. Combat maneuverability has not been tested and is PROHIBITED.
2. Combat Rescue is not possible because the V-22 is not and never was
intended to have a combat rescue hoist installed.
3. Autorotations are Prohibited.
4. The compromize design and resulting aerodynamics have resulted in:
a. higher Downwash
b. no autorotation capability
c. inclination to enter VRS undetected

Conclusions:

The V-22 is an extremely expensive experimental aircraft without any justifiable Combat capabilities for use in actual Combat situations.

The V-22 is NOT a COMBAT capable/suitable AIRCRAFT

Recommendation
If the never satiated desire for Congressional power and PAC monies -- are to be taken care of ---it is Recommended that the V-22 Program, its aircraft, material, and remaining funds be distributed to NASA and the FAA, to determine if their is any potential safe use of the assets
:)

[This message has been edited by hpdunn (edited 04 May 2001).]

To VLift and Lu

VLift you said:
"If the aircraft is in an autorotational situation and has no appreciable forward speed component the rotor RPM will slow, as the resultant realitive wind is at too great an angle to provide for the forward rotation of the blades.
As the rotor slows the air being pushed down in the center of the system is even less and more of the center area is occupied by air going up through the rotor system. So, more of the rotor system is not contributing lift, aircraft descends faster."

Sorry old chap but this is not wholly correct.

You can quite safely carry out a vertical autorotation, with no forward airspeed and no power applied the NR will settle at a higher level than forward auto, but you can remain in this situation as long as you wish. All of the flow through the disk is moving up (lift is produced by the reduction in pressure above the rotor disk, it does not require downward flow - we are talking is Benoulli not Newton).

The problem comes when the pilot decides that a high speed vertical landing may cause an unforseen claim on his life insurance.

Power available: If he applies collective and therefore power he can then induce a VR state quite quickly(!), thus he must transition into forward autorotation before applying power to recover.

Engine Off: To recover kinetic energy from the system to effect a safe landing he needs forward speed, and must therefore transition to forward auto before landing either by collective and flare or collective only.

My most exciting engine off happened in a PFL which began with a vertical auto,followed by a late transition (after my loud "I HAVE CONTROL!) to 35 kt forward auto then a last minute collective check (no flare) to run on as NR decayed rapidly. No sign of VR though.

Conversely my one VR incident occured in a high hover (1000') downwind, recovery by entering auto and stuffing the nose down took 800', close but still 200' in hand!

GA

My name is continually referenced in some of the posts on this thread. I will repeat that any comments made by me are dated, as it was almost six years ago that I worked on the V-22 program.

Two of the comments I made regarding the V-22 are:

1) The rate of descent on the V-22 if the pilot elected to perform an autorotation is somewhere between 4-6000 feet per minute and at that rate of descent the pilot can’t arrest his speed to an acceptable level. I brought this to the attention of Boeing and I was ignored.

2) The “Proprotors” as they are officially known are mounted in rubber. When the pilot performs a maneuver while in the aircraft mode the gyroscopic turning moment on the Proprotors will cause them to precess. This misaligns the thrust line of the Proprotor and can cause control problems. Built into the Proprotor is a series of flapping sensors. These sensors “sense” the blade movement and send a signal through the autopilot and the control servos bring the Proprotor back to the neutral thrust line. This causes a very high demand on the hydraulic system and reduces the overall reliability of the hydraulic system. I brought this to the attention of Boeing and they stated that it was a Bell problem. Boeing designed the servo control system. Bell designed the Proprotor. I brought this to the attention of Boeing on four more occasions. The answer was always the same. On the fifth occasion I was fired.


[This message has been edited by Lu Zuckerman (edited 01 May 2001).]

V-22 Blade Loading Under FAA Part 29
 

Lu and Unctuous and all takers--
Would it bother any of you if you found the Load Factor (leading edge blade stall)for V-22 in hover, as being below FAA Part 29 at a g-load of about 1.3 to 1.4? Can anyone confirm or recalculate?
Does as C sub t over sigma (aerodynamic blade loading) of 0.18 seem a little high??

[This message has been edited by hpdunn (edited 13 May 2001).]

Obviously the characteristics of a prop-rotor are quite different to those of a helo rotor. The critical area is in the size and strength of the vortices generated and the rate of spread of the vortex sheet.

On the subject of the December crash it has now been admitted that it was not a software flaw, but a control law design flaw:
see Professor Ladkin's lead-in article below and my much earlier comments on this page:
http://www.pprune.org/ubb/NonCGI/For...ML/000658.html

From Ladkin
My two notes on the December accident to the Osprey, the V-22 tilt-rotor vehicle, subsequent to the JAG briefing and to the appearance of the Blue Ribbon Panel report, appeared in Risks 21.33 and 21.38 respectively, and I also forwarded them to the list.

Readers will recall that I concluded from the JAG briefing material in my note in Risks 21.33 that a failure caused by a software error, which was subsequent to the hydraulic system failure, was indicated by the JAG briefers. The briefers called it a "software anomaly", and indicated that the Primary Flight Control System did something it should not have done, because of software commands. This indicated to me either an implementation failure to meet the design specification, or a failure of the software design to meet PFCS requirements. This is my definition of "software error".

Two circumstances caused me to query that a software error had in fact occurred. First, conversations with New Scientist reporter Duncan Graham-Rowe, and second, the appearance of the Blue Ribbon Panel report with its brief consideration of software reliability (less than one page out of nearly two hundred), along with its recommendations of integrated testing (with pilot-in-the-loop) but no software inspections (which I would have expected, had there been reason to believe that a software error in the PFCS had caused an accident). I produced a ponderous analysis of the JAG briefing and the Blue Ribbon Panel report section on software reliability. The analysis appeared in Risks 21.38.

I concluded that there had been no software error in the strict sense above, that the PFCS indeed had done what it was designed to do, but that the actual physical consequences of that design in that situation had not been sufficiently appreciated at least by the flight crew, and maybe by some or other part of the operations team or engineering teams involved. I enumerated three specific ways in which that might have occurred.

Yesterday I spoke with Professor Gene Covert, one of the Blue Ribbon Panel members, and a colleague of Nancy. I put my conclusions to him. Although a significant amount of his information is privileged, he was able to confirm that there had been no software error in the strict sense above, and that my conclusion (as above) broadly represented likely scenarios for the genesis of the control behavior exhibited in the December accident.

PBL

MV-22 Osprey reprieved..
 

Weapons Buyer To Keep Osprey Program
By ROBERT BURNS, AP Military Writer

WASHINGTON (AP) - The Pentagon (news - web sites)'s new chief weapons buyer has decided not to cancel the troubled V-22 Osprey (news - web sites) aircraft program but has taken acquisition authority for the program away from the Navy.

The Osprey, a hybrid aircraft that takes off and lands like a helicopter but flies like an airplane, is designed mainly for use by the Marine Corps, which is part of the Navy Department. After a fatal crash last December - the second for the Osprey in less than a year - the Navy grounded the fleet and put off a decision on whether to begin full-scale production.

The decision to go ahead with the Osprey program was made last week by Pete Aldridge Jr., who was sworn in as undersecretary of defense for acquisition on May 11. The decision, which was not publicly announced, was first reported in Monday's edition of Inside the Navy, a trade publication.

Aldridge told the Navy to go ahead with buying additional Ospreys, but at the lowest possible rate that ensures the manufacturer can continue to work on improvements to the aircraft. He did not specify what that production rate will be.

The decision fits with the recommendation of a Pentagon-appointed panel of experts, which said May 2 that because of serious concerns about the Osprey's safety and design the aircraft should continue in production at a "minimum sustaining level'' until changes can be made.

The Osprey is manufactured by Boeing Co. and Textron's Bell Helicopters unit.

In Philadelphia on Monday, the widow of a Marine pilot killed in a V-22 crash last April urged Congress to ask tough questions before putting the tilt-rotor planes back in operation.

Trisha Brow told a House Armed Services subcommittee hearing that it would be a "horrible disservice'' to the families of 23 Marines killed in the two Osprey accidents last year to fail to solve the aircraft's problems.

"We have paid more of a price for the Osprey than any other taxpayer will ever be asked to pay,'' said Brow, whose husband Lt. Col. John Brow and 18 other Marines were killed in a crash near Tucson, Ariz., on April 8, 2000. A crash last December in North Carolina killed four Marines.

Aldridge took acquisition authority for the V-22 program away from the Navy "because this program is at a critical stage,'' Pentagon spokesman Lt. Col. Dave Lapan said. That means all future production decisions will be made by Aldridge's office rather than the Navy's senior acquisition executive.

It is not clear when the Ospreys will be cleared to resume flying, Lapan said.

He said the Pentagon is forming a new V-22 executive committee to focus in detail on key issues such as testing, technical risk and cost. The committee will have senior representatives from the Navy, Marine Corps, Air Force, Special Operations Command as well as the major V-22 contractors.

Also, Aldridge's office will begin a series of detailed reviews starting in August, Lapan said.

tHIS MAY JUST BE THE BEGINNING--

The v22 Panel is still working away.
The Air Force and others may start looking at aerodynamic blade loading and stall margins (near lack thereof)

The game ain't over til the fat lady sings --several months from now.

hpdunn,

The fat lady has sung. The song was the death knell of the transport helicopter. The tiltrotor is here to stay.

The Sultan

I have to agree with the Sultan. The fat lady has been building to a sonata since last month when the Blue Ribbon Panel appointed by the Secretary of Defense to do an independent investigation came back with the UNANIMOUS recommendation to go ahead with the program. The best part is that they pointed the finger at those responsible for taking shortcuts in the program that led to the problems they’ve had, and they said to put whatever money into the program is needed to fix those problems that the independent panel said can easily be done if corners are not cut. The other investigations that are in progress all look at the same data and no doubt the FACTS will speak louder than the press!!!

The endless discussions over the V-22 program are now pushing around “MUTE” points- the program WILL move ahead.

Anyone who wants to spend their time making up theories, posting nonstop redundant articles, and attacking the V-22 can have at it- but the proof is in the pudding. The V-22 will move ahead and those standing in the corner with the red faces will be the ones who couldn’t quite figure it out.

I've no wish to enter into a dispute...but I never could keep me gob shut!
Long live the V-22 & roll on the 609. The future is coming & it looks good.
The speed of a fixed wing coupled with the versatility of a wokka! Superb!

Sorry...how fast does a honda fireblade go?? Is that all! Sheesh....run little man!

Are their any rotor aero engineers out there who understand that the big secret of the Osprey (i.e Albatross)is that it has a PROPELLER blade on it that stalls out at 1.3 to 1.4 g's in GW hover/conversion modes, and does not even marginally meet even FAA certification standards for Aerodynamic Blade Loads?? Would you jump in this machine for Combat Manuevers, or Combat Rescue (no hoist position found beacause of downewash velocities?? OR -- can you imagine the pleaseure a radar directed missle gunner will have when he sees a bird with two 38ft diam propellers heading his way? Initial estimaets are that of 1-2 747's headed his way.

It IS time to go back to realities of engineering and design parameters and get off the gee whiz admiration approach :)




[This message has been edited by hpdunn (edited 24 May 2001).]

The Proof is in the Pudding............

I'm curious, what G-load is a helicopter rotor supposed to stall at?? same conditions: GW hover.

The issue is how much thrust the rotor has above that for its basic lift. Most helicopters have about 1.9 to 2.2 G's of thrust available at low speed, mostly due to the excess thrust built into the rotor for use at high speed. This is expressed as the "aerodynamic blade loading" where each square foot of blade is tasked with providing a given amount of lift. Like wing loading, this is a measure of how much extra thrust there is for maneuvering. At the aerodynamic blade loading limit, the rotor stalls, and the aircraft can fall through, or lose control.

Tilt rotors have much more highly loaded rotor blades, mostly because this increases hover payload, and alsobecause when the tilt rotor gets to high speed, the rotor becomes a propeller, and doesn't have to provide lift. The typical tilt rotor has at least 50% more aerodynamic blade loading than the typical helicopter, reducing the rotor thrust in helicopter mode. A typical helicopter has about twice as much low speed maneuver capability as a typical tilt rotor.

Most tilt rotor designs are limited to about 1.4 to 1.5 g's at helicopter mode at mission weight at sea level. For all rotors, this goes down with reduced density at altitude.

(for the techno types, aerodynamic blade loading numbers follow:
Helo about .08, tilt rotor about .125 to .15, typical max blade loading at stall .17 to .21)

A few good questions from a few good men...

I thought I might share these concerns with you lot--they seem like valid concerns to me:

Best put by a friend in the USMC:

"When are the engineers going to tackle the problem of adding armor? If it's to be internally mounted, the skin of the airframe(along with stringers and other structural support) will have to be modified which will present a number of changes to the flight characteristics of the bird: airfoil will be different which will affect drag-lift-fuel consumption-handling-et al; which in turn will impact range and load, weight and balance, and any attendant maintenance peculiarities which is also going to impact mission capability. If internally mounted, how easily accessible are the mounts going to be - for corrosion treatment/inspection and subsequent hardware or component replacement? And if externally mounted, granted accessibility will not be much of a problem for maintenance - how big a headache is it going to be @ 250 knots? What a drag! This is not a flashback to the 60's . . . or is it? When we put armor on the 46 (pilot, flight control closet, engine) it was not exactly a transition that could be described as smooth as a baby's behind. The impact it had on the airworthiness was significant. I suspect the same will hold true for the Osprey. I wonder if any of the wonder boys in engineering have mentioned any of this to the Commandant. Not yet, at any rate; what are they waiting for? A contract to build 360 of them? Hmmm. What else have they neglected to mention? Hydraulic lines? Oh, no. They have mentioned them. Particularly after the crash on 11Dec. Something about the metallic lines rubbing on wire bundles - what the hell are wire bundles being made out of on that airframe? They ought to use THAT material for the armor that's got to added if the V22 expects to have any longevity in a hot zone offloading or onloading our fellow Marines. Semper fi."

What are your thoughts on these concerns? Mr. Lappos, if you're haunting these rooms, what's the good word?

------------------
"You did WHAT"?!

Back to the top.

Any help on this would be greatly appreciated.