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And Frank Robinson is kicking the pants off of Eurocopter. |
....Torrance has claimed for years that Robinson is the world's leading producer of helicopters, but Eurocopter and Sikorsky are the big dogs in terms of revenues; Robinson is in a different league.... As another famous Frank once crooned, "Yes, there were times I'm sure you knew When I bit off more than I could chew But through it all, when there was doubt I ate it up and spit it out I faced it all and I stood tall and did it my way" :cool: |
Poor ol Sasless is getting beat up now, first he goofs on LTE being a Bell specific problem then he blows on about Bells specifc lack of inventiveness
Yeah compared to Eurocopters Alouette 2,3,Astar,EC130 line that are so similar ( Eurocopter even tells people the cabin on the EC130 is practically the same dimensions as the Alouette 3) and Sikorskys S76A,A+,C,C++,D. What about Robinsons R22,44,66. Etc Etc Aviation design is about minimising the risk (unless youre Burt Rutan). Example..after years of Rolls Royce saying they werent going to design any new engines they produce the RR300. Lets get back to the point of this thread which is talking about what a magnificent aircraft the V-22 is. Magnificent.. |
Tuk....please don't speak for me as you have difficulty enough on your own.
I said the LTE terminology was invented by Bell to explain the shortcomings in their tail rotor performance....and that language was grabbed by the FAA and others and then applied to all single rotor helicopters. I did say other types do not have the problems that Bell does in the 204/205/206 series of helicopters re tail rotor performance. So...back under the bridge with you. From a post made by Brian Abraham here in Rotorheads a while back that pertains to the discussion of LTE. The Bold print was my doing.... kflexer - The following is what Nick Lappos has to say on LTE. (Nick was test pilot for Sikorsky and did the work on the 76 - among other things). The real skinny on LTE is simple and quite easily stated: All rotors lose thrust when operating in disturbed air, including tail rotors, main rotors and fantails. LTE sets in when there is so little thrust margin that the loss of the maybe 5 or 10% of the thrust is enough to kill you. With a really marginal design, that slight loss of thrust unleashes the massive main rotor torque, and the aircraft bites its pilot big time. I cut my teeth on the old AH-1G snake, with its way too small tail rotor, and had at least my share of 360 turns while trying to get over someplace to cut the throttle. LTE only affects those helicopters that have too little tail rotor thrust margin. Period. It is really not LTE it is "Not Enough Tail Rotor". LTE happens when the tail thrust is consumed by several possible upsetting factors, and when the remaining thrust, by marginal design, is simply inadequate. Yes, inadequate. These possible tail thrust reducers are: 1) main wash into the tail rotor, as illustrated in the LTE handouts that we've all seen. 2) using somewhat too much main rotor thrust (collective pitch) at the bottom of an approach, especially in critical tail thrust conditions. I can touch the left pedal stops on any helo by simply raising the collective pitch until main torque washes out all tail margin. One inch more collective and WATCH out! You get LTE, surprise, surprise. 3) terminating an approach with a critical wind condition, where the wind is a few knots more than your helo can stand. I did a study on "LTE" accidents to support a regulatory change meeting I was attending, and , wow, it was some surprise to find that about 95% of all LTE accidents were restricted to one brand name, and all LTE accidents were experienced by helicopters with very little cross wind capability. The cure for LTE is quite simple - get a helicopter with a bigger tail rotor, as proven by the certified crosswind capability. Don't get in one that has an LTE history, and don't buy the bull that LTE is a pilot error problem. Don't buy into the new certification rules that allow you to operate with a helo that has no crosswind capability. If you do, get a good helmet, and a good insurance agent. BTW, the LTE study that I did was opposed by an engineering manager from that particular manufacturer because "LTE is a pilot error problem, plain and simple" I asked how so many bad pilots were flying his helos, and expressed our luck that so few of these dumbos were flying all the other brands. In the fantail, sometimes I can feel the main rotor wash flow into the tail, the pedal moves a few percent the noise increases, and that is that. The big tail surfaces on the fenestrons and fantails are because the fan doesn't respond to small yaws, so the aircraft will snake a bit, unless the vertical tail is big enouigh to keep the nose ahead of the tail. On regular tail rotors, the tail rotor responds strongly to change thrust when some sideslip develops, and the yaw stability to small disturbances is strong. In fact the tail rotor area is as powerful as a vertical fin that is about 4 to 8 times bigger than the tail rotor. This is one of the reasons why the Fantail is able to snap turn, because the fan doesn't care where the wind is from, it keeps its thrust and bending closer to normal. Under big sideslips, a tail rotor is positively screaming from the big stresses it develops. With the same maneuvers, the Fantail is calm as can be. I put my money on the Accident Statistics, Research, and expertise of Mr. Lappos and definitely not on Bell and the FAA. BELL and the FAA are entitled to their opinions but not their own "facts"....as we all know true "Facts" are obstinate things. You will notice the FAA mentions mechanical malfunction but ignores design failure when describing the cause of LTE as they stake their position on their standards being adequate. How do they now admit they are not after all these Bell 206's have been built? LTE is a critical; low-speed aerodynamic flight characteristic which can result in an uncommanded rapid yaw rate which does not subside of its own accord and, if not corrected, can result in the lossof aircraft control. 6. LTE is not related to a maintenance malfunction and may occur in varying degrees in a single main rotor helicopters at airspeeds less than 30 knots. L T E is not necessarily the result of a control margin deficiency. The anti-torque control margin estab- lished during Federal Aviation Administration (FAA) testing is accurate and has been determined to adequately provide for the approved sideward/rearward flight velocities plus counteraction of gusts of reasonable magnitudes.This testing is predicated on the assumption that the pilot is knowledgeable of the critical wind azimuth for the helicopter operated and maintains control of the helicopter by not allowing excessive yaw rates to develop. |
Much of the concern over LTE comes from an early design flaw built into Bell 204 and 205 tail rotors and later carried over to the AH-1G Cobras. These early Bell tail rotors were situated on the left side of the tail boom and turned in an anti clockwise direction. This combination resulted in the tail rotor blade traveling down through the main rotor flow rather than up through it. Certain low speed and cross winds situations dramatically degraded tail rotor performance resulting situations identified as LTE. Bell rectified this by retaining the same tail rotor but relocating it on the right side of the tail boom. In this configuration the tail rotor blades travel up through the main rotor flow and were less susceptible to LTE.
There have been many instances where modern helicopters have experienced some form of LTE. The Blackhawk rolling down the hill and Erickson Aircrane rotating out of control during a water pickup are two recognizable examples. In these examples main rotor torque required exceeded tail rotor anti torque available. The tail rotors were operating as designed but in excess of there capabilities resulting in a loss of directional control. |
Is LTE caused by a mechanical defect? No. LTE is caused by an aerodynamic interaction between the main rotor and tail rotor. Some helicopter types (Jetranger) are more likely to encounter LTE due to the insufficient thrust produced by having a tail rotor which meets certification standards, but which is not always able to produce the thrust demanded by the pilot. Quote taken from a UK Safety organization report on LTE. |
I see theres been another CH-53 accident in Afghanistan, reported as a D model which seems surprising as theyd be long in the tooth now. Also mentioned the Hawaii based unit will be transitioning to the V22.
The article talks about a possible technical fault but who knows with newspapers these days. Either way a new V-22 has to be alot safer than an old CH-53D. |
It was a D model. There are still two Hawaii 53D squadrons. They're both in line to be replaced by the V-22.
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Anticipated V-22 Acquisition Slow Down
Exclusive: Pentagon budget eyes $178.8 bln for R&D, procurement By Andrea Shalal-Esa WASHINGTON | Sat Feb 11, 2012 3:33pm EST WASHINGTON (Reuters) - The Pentagon's $525 billion budget plan for fiscal 2013 calls for spending of $178.8 billion to develop and buy new warships, fighter jets and other major weapons, a 7.5 percent drop from the level initially projected for the coming year, according to a detailed budget document obtained by Reuters. The total acquisition spending amount is about 12.2 percent down from the level the Pentagon requested in last year's budget, the document shows. The fiscal 2013 plan foresees spending of $109.1 billion for procurement and $69.7 billion for research and development, compared with earlier projections of $117.6 billion for procurement and $75.7 billion for R&D. The document shows that the U.S. military is maintaining high levels of spending on most aircraft and ships as it shifts its focus to the Asia Pacific region, a new military strategy announced last month by President Barack Obama and Defense Secretary Leon Panetta. At the same time, funding for ground vehicle programs will be far lower as the U.S. military reduces the size of the Army and Marine Corps after 10 years of war in Afghanistan and Iraq. Panetta last month gave highlights of the 2013 budget, his first as defense secretary and the first that takes into account a deficit-reducing measure passed by Congress that requires cuts of $487 billion from projected spending over the next decade. It is also the first Pentagon budget since the September 11, 2001, attacks that requests less funding than the year before. Weapons makers like Lockheed Martin Corp, Boeing Co, Northrop Grumman Corp, General Dynamics Corp, Huntington Ingalls Corp and Raytheon Co have been anxiously awaiting details about their programs. The Pentagon is due to formally release the details on Monday when Obama sends his 2013 budget request to Congress, which must approve the spending plan. AIRCRAFT FUNDING DOWN The plan for the 2013 fiscal year, which begins on October 1, requests $9.17 billion for the Pentagon's biggest weapons program, the F-35 Joint Strike Fighter, down slightly from $9.25 billion requested in fiscal 2012. That includes $2.7 billion for ongoing development of the radar-evading supersonic jet, and $6.15 billion to pay for 29 jets, down from $6.33 billion for 31 jets in 2012. Panetta announced last month that the Pentagon would slow the ramp-up in production of the new fighter to allow more time for testing and avert costly retrofits. Overall spending on aircraft programs will drop 12 percent to $47.6 billion in fiscal 2013 from $54.2 billion in the fiscal 2012 budget request, mainly due to a 41 percent drop in funding for the Lockheed-built C-130J transport plane, and a 32 percent cut in funding for the V-22 Osprey. The Pentagon proposed spending $835 million on seven more C-130J airlifters in fiscal 2013, down from $1.43 billion for 12 planes in fiscal 2012. Funding for the V-22, a tilt-rotor aircraft built by Boeing and Bell Helicopter, a unit of Textron Inc, would drop to $1.91 billion for 21 aircraft, from $2.8 billion for 35 planes in fiscal 2012. The plan foresees spending of $1.25 billion for six high-altitude unmanned Global Hawk spy planes built by Northrop Grumman - three for NATO and three for the Navy. Panetta announced last month that the Pentagon was cancelling work on the Air Force's Block 30 variant. The plan would increase funding for the AH-64 Apache helicopter built by Boeing by 55 percent, funding 40 remanufactured helicopters and 10 new aircraft. Northrop Grumman and Lockheed also have a big role in the program. Funding for the UH-60 Black Hawk helicopter built by Sikorsky Aircraft, a unit of United Technologies Corp, would continue a five-year procurement agreement with $1.3 billion for 59 of the twin-engine helicopters. GROUND VEHICLE BUDGET DROPS 32 PERCENT The Pentagon's spending plan includes $10.9 billion for ground vehicles, 32 percent less than the $16 billion requested in fiscal 2012. The new request includes $117 million for continued development of a new light tactical vehicle for the Army and Marine Corps and a heavier new Ground Combat Vehicle. Funding for the Family of Heavy Tactical Vehicles built by Oshkosh Corp would drop to $58.1 million for 1,534 vehicles from $650 million for 9,336 vehicles funded in fiscal 2012. Missile defense spending would remain fairly stable at $9.7 billion under the fiscal 2013 request, maintaining work on several air and missile defense capabilities such as the Patriot PAC-3 missile built by Lockheed. It would fund the MEADS joint program with Italy and Germany at $400.9 million, completing development testing. Shipbuilding programs would get $22.6 billion in the fiscal 2013 request, down from $24 billion in the fiscal 2012 request. That will fund 2 Virginia-class nuclear attack submarines, 2 DDG-51 destroyers, 4 Littoral Combat Ships and the first year of construction of a second new aircraft carrier. Space programs would get $8 billion, a drop of 22 percent from the $10 billion requested in fiscal 2012, due to fewer satellites and launches, and the cancellation of Northrop's Defense Weather Satellite System. |
Venanzi said autorotation tests have been conducted at altitude, and that “it doesn’t take much altitude” to achieve a power-off full flair to a sink rate of zero fpm. What about the Osprey.....isn't 1,600 feet the number given for the ability to achieve forward airspeed for a fixed wing type emergency landing and no ability to "auto-rotate"? Certification requirements? Safety standard criteria difference? Design difference? |
Don't know who is giving out 1600' as a key altitude for a fixed wing emergency landing.
The V-22 does have the ability to autorotate. |
Section 2.5 starting on page 27 discusses "Autorotation" in detail, the procedures, probability, shortcomings, and training. It is an older document (circa 2001) but I would assume it is still valid as to describing the situation....and that suggested improvements in training, simulators, and NATOPs procedures have been made.
http://www.fas.org/man/dod-101/sys/ac/v22-report.pdf I may be getting old and worry about my mortality more than I used to do...but even at spending 30% of my flight time in a phase of flight where the lack of a viable auto rotational capability might prove deadly....it would give one pause for thought. If it isn't 1600 feet....what does the H/V diagram look like? |
Autorotation Vs Airplane Mode Glide
I have no doubt that the V-22 has the ability to establish an autorotative descent. The report provided by SASless clearly states that, “that the probability of a successful autorotational landing from a stable autorotative descent is very low.” As a result the manufacturer implies that the recommend method of landing with both engines inoperative would be an airplane type glide to a touchdown to a hard surface. SASless, it sounds as it 30% is the best one might see. From my perspective nearly 100% of the time a viable autorotation is not a choice. An airplane mode glide to a touchdown gets my vote as the procedure of choice, if for no other reason than that it will provide a little additional time to sort out the situation while inroute to the mishap site.
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If I had the time and interest I would go back through the thread and find the information John Dixson posted that detailed the Emergency Procedures and a discussion of the H/V diagram which showed a fair old height being required for the transition from Hover Mode into a No-Engines Operating Airplane Glide. It was startling to see how high one needed to be in order to achieve a proper Glide Speed and descent rate.
As the Marines say...it is not a helicopter....it is a tilt rotor and thus cannot be expected to autorotate like a helicopter.:E Also...the odds of having a dual engine failure is quite remote....but possible as we all know about "Sod's Law".:{ The trick will be operating in the Hover Mode at heights lower than required to make that transition....where one cannot autorotate or go gliding....not that will ever happen mind you!:oh: The difficulty of a transition from Hover Mode to an authoritative descent and landing must rather sporty as it is only done in the Simulator....and unless I misunderstand....it was not done in much detail during testing. The other quote I found interesting is the Civil version has a different system for controlling the prop rotors angles and uses "Detents". I wonder why the difference and which system is the better? Could it be the Military froze the design in order to get into production and decided not to use the "Detent" method as Agusta has for the 609. |
Ospreydriver: curious.
Do you guys do practice autos in the Sims? That Rate of Descent I saw in a NATOPS manual (not sure how current it is) looked pretty sporting! Looks like a tough maneuver from the description. |
Venanzi said autorotation tests have been conducted at altitude, and that “it doesn’t take much altitude” to achieve a power-off full flair (sic) to a sink rate of zero fpm. Presumably, a run-on landing in helicopter mode would be less risky than a forced-landing in King Air mode. Either way, the landing is going to be breathtaking! With regard to the former, imagine timing that flare? Hoo! But even King Air pilots don't practice dual engine failure landings in real life - probably not even in the sim. Then again, King Airs aren't often asked to hover. However, one has to chuckle a little at Venanzi's clever use of that vague, "doesn't take much" phrase. Sooooo...how much is "not much?" And how much more "not much" would it take for the heavier V-22 to flare to zero fpm in an auto? Ah, semantics, gotta love them. When it comes to engine failures, we know that the transition from hover-to-stabilized-auto or hover-to-airplane-mode is going to take up quite a bit of altitude. But let's dismiss the idea of having a dual engine failure while hovering and then transitioning to airplane mode. When would that ever happen? When would a V-22 be hovering high enough to even consider such a procedure? On the other hand, if both of an Osprey's engines quit when it's cruising along up high, it becomes a bank safe with little stubby wings. Look for something soft to land on (hopefully near a hospital), not Interstate-10. If you have a dual engine failure at the end of a flight when you're on approach and transitioned back to helicopter mode, you're pretty much screwed; we understand this. But you would have to be having a REALLY bad day. (Hopefully nobody would experience a dual engine failure on take-off.) It's a compromise aircraft. Those who fly it (and fly in it) accept those compromises that come with the increased capability. They look at the instances of dual engine failures in existing multi-engine aircraft and they consider the risk of that particular emergency to be low enough to not worry about. |
Osprey Driver.....found a reference to the 1600 Feet AGL number.
The proper wording should be "....following sudden dual engine failure or failure of the operating engine in OEI Flight....". Indeed, the 2005 OT-IIG report itself says in reference to “emergency landing profiles following sudden dual-engine failure” that: “dependent on altitude, the aircraft flight manual directs conversions to airplane mode or autorotation.”167 Yet this report’s own executive summary states: “Emergency landing after the sudden failure of both engines in the Conversion/Vertical Take-Off and Landing modes below 1,600 feet altitude are not likely to be survivable. ... The V-22 cannot [author emphasis] autorotate to a safe landing.”168 A subsequent comment in the summary states: “Additional flight tests should be conducted to provide validated procedures for dual-engine failure.”169 Any volunteers? Clearly, safe engine-out landing is a major unresolved issue for the V-22. |
The 1600' remark can actually be attributed to (OT-IIG)
http://pogoarchives.org/m/dp/dp-V22-dote-092005.pdf Page 35 under dual engine failure To convert the nacelles from 60 to 0 degrees requires about 8 seconds and the aircraft must be above ground level by 1600' in order to complete the conversion prior to impact Emergency landing after the sudden failure of both engines in the Conversion/Vertical Take-Off and Landing modes below 1,600 feet altitude are not likely to be survivable SAS, where is your quoted text from? |
Page 298.....Operational Suitability
Original quote came from the Gailliard article.... http://www.dote.osd.mil/pub/reports/...2005v-22xs.pdf http://www.cdi.org/pdfs/gailliard%20on%20v-22.pdf Mr. Gaillard seems a bit unimpressed with the Osprey....and reading his paper does raise some interesting questions. One example that I just read.... the countermeasures dispensing system was found to have insufficient capacity for longer missions, and radar reflection from the V-22’s total propeller disc area of more than 2,267 square feet rivals that of two Boeing 707s in formation.146 (Given that situation, one can only wonder at the logic behind the development of top-secret “stealth paint” for the fuselage at a cost of $7,500 per gallon; the one aircraft they painted required 10 gallons for a paint job costing $75,000—but those huge, whirling discs were still there, bouncing back radar signals with gusto.) |
Sure enough, its there, i missed it in scanned version I linked to.
My question as to how that conclusion was arrived at remains. Mr. Gaillard seems a bit unimpressed with the Osprey |
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