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I assume they have avoided HV curve demonstrating then, because that is a much higher risk test regime. |
That's incredible - it doesn't look like it could auto-rotate - I'd just assumed the disc loading would be too high and it would be too heavy.
Seems they're already thinking of a SAR role: https://www.slideshare.net/webfinmec...rch-and-rescue It'd be ideal for long-range, over water winching off ships - the sort of thing done off the coasts of Australia and NZ. Great for medivac too. |
Spot on 212. But doing the H-V and the Cat A tests await, sooner or later. I wondered at the emphasis on “ simulation “. Could it be that they intend to do the autorotative descent, approach, flare, and then do a power recovery-their interpretation of a simulation: everything less the touchdown? There is precedent for that, although in military certification. |
Tilt Rotor Autorotation performance IS a risky business.
One source of information: https://fas.org/man/dod-101/sys/ac/v22-report.pdf A Quote from the USMC Osprey Fact Book found at DTIC. Myth: The V-22 is unsafe because it can’t autorotate Fact: The V-22 is a tiltrotor and does not rely on autorotation for a survivable power-out landing. The wide separation of the engines and the ability to drive both rotors with one engine make a power-out landing extremely unlikely. However, if required, the V-22 can glide for a predictable run-on landing in airplane mode, much like a turboprop. From a "Vertical" Article: If Things Go Bad Nearly every system in the Osprey is triple-redundant. There are three flight control computers, three lightweight inertial navigation systems, three hydraulic systems and four generators. The V-22 only requires one of these systems to safely continue flying; the others exist for safety purposes, yet have identical functionality. This doesnt mean that things cant go wrong as with any aircraft, there are obvious emergencies that require learned procedures to overcome. Stalling the Osprey is a definite possibility when youre flying in the low end of the airplane-mode flight envelope. Typical stall speeds occur around 105 to 110 KCAS, depending upon aircraft conditions; fortunately, its rare to be flying that slow without having converted. One situation that can be encountered, however, is an accelerated stall, because the stall speeds can increase upwards of 140 KCAS as the bank angle increases. Normal stall characteristics in the V-22 are very benign: about the only indication that the airplane is stalled is the increase in descent rate on the display. Because the Osprey exhibits blown wing characteristics, it is very difficult to develop a full stall, thereby making the effects less dramatic. Continuing into a full stall will result in a nose-down pitching moment, but the effect is not nearly as dramatic as with some airplanes. Recovery is the same as with any airplane: reduce the control stick backpressure and apply full power: the Osprey will break the stall almost immediately. On the primary flight display, a stall meter is displayed below a 35-degree nacelle setting, showing a dynamic percentage of the stall to assist the pilot. Probably the most discussed issue with the Osprey is the lack of autorotational ability. Of course, the Osprey spends the overwhelming majority of time flying as an airplane, so its easy to see that the need for autorotation is pretty minor but as Murphys Law states, when you least expect it, things can indeed go bad very quickly. Technically, the Osprey can actually enter autorotation, although the flight characteristics are extremely poor. Reduce the TCL to the full aft position with the nacelles full aft and the rotor system is being powered solely by the upward flow of air through the rotors. The greatest detriment to the autorotational capability of the Osprey is the very-low-inertia rotor system, which doesnt store as much energy as a traditional helicopter rotor system. Rotor r.p.m. will bleed off very quickly if the autorotation is not entered almost immediately, and it is very difficult to recover lost r.p.m. Stopping the nacelles at the full aft position is also critical, because any edgewise airflow over the rotor will rapidly decay r.p.m. This also corresponds to very poor qualities during the flare and touchdown portions of an autorotation. The autorotational descent rate is quite large about 5,000 feet a minute and an aggressive and rapid flare is necessary to arrest that rate. An increase in r.p.m. will be briefly noticed here; but, again, due to the low inertia of the rotor system, that gained r.p.m. will very quickly start to decay. Autorotations are taught and practiced in simulators with varying degrees of success. The simulators are designed to indicate a crash if any structural load limitations are exceeded; most autorotations end in a red screen. The truth of whether an autorotation is survivable, though, is hard to define. Chances are that an autorotation in an Osprey would be an extremely difficult maneuver, with survival owed more to luck than skill. The loss of both engines in airplane mode requires very similar emergency techniques as utilized in a twin-engine airplane. However, as mentioned earlier, unlike an airplane it is impossible to feather the proprotors. The glide ratio of the Osprey is about 4.5 to 1 and the rate of descent while windmilling is about 3,500 feet a minute at 170 KCAS. Landing speeds vary with aircraft weight, but a middle-of-the-envelope speed is 130 KCAS. Unfortunately, the proprotors will definitely impact the ground, and converting the nacelles is not recommended. A safety design feature of the proprotors, however, is for them to broomstraw and throw the resulting fibers away from the fuselage to minimize damage to the occupants. Unfortunately, this characteristic has been tested in accidents; fortunately, it works as advertised. |
I know that a lot of helicopter guys whine and moan about it, but this whole "Osprey can't autorotate" thing is just silly. First of all, do we take CH-53E's out, shut all three engines off and go to the ground? Do we take King Airs up and shut 'em both off and glide to a landing? Why would we ever do that?
Secondly, let's think about when an Osprey autorotation would be necessary? The thing would not be converted to helicopter mode way up high - they do that when they're descending and decelerating for landing. Meaning that the Osprey would be quite low...probably too low to successfully transition from powered flight to autorotation. We have to get off this thinking that a total power-off event could happen to multi-engine aircraft. We need to accept the fact that if it ever happens, it won't be pretty. So have the crews practice it in the sims. And then hope they never have to do it for real. |
The question relates to certification more than to operations.
Does the various authorities allow the aircraft to be certified by use of Sim. Demo's only or not....or does the aircraft have to be flown in the tests to prove what its performance is? Where does an authority draw the line between theory and reality when certifying a passenger carrying aircraft? |
https://www.rotorandwing.com/2018/10...wvY1FuSjRYYSJ9
"We also have PT6 engines, which never fail." |
Real World Plus Simulation for Certification
Over ten years ago Bell pilot Roy Hopkins flew 609 Ship 1 on an autorotation test flight that proved the aircraft rotors had sufficient energy to safely land the aircraft. In airplane mode the engines were brought to idle and an emergency reconversion to helicopter mode was conducted. Roy then executed an autorotation manuver that reduced aircraft vertical decent to zero and forward speed to near zero. The only thing missing from this test flight being acceptable for certification was it was conducted at altitude and the aircraft never touched the ground. So what Leonardo is requesting is only simulation of the aircrafts handling qualities as the aircraft touches down. Not if the rotors can arrest the aircrafts decent in autorotation. Added note. Roy actually pulled to much collective and Ship 1 not only stopped decent by increased altitude before it was reduced to achieve simulated touchdown. Proving the aircraft has rotor energy reserve. |
CTR,thanks for the note about an exceptional bit of airmanship/test flying by Mr. Hopkins, whom unfortunately I have not met but whose reputation had certainly reached our test pilot office.
Your last line provokes a question as to why, therefore, it is now seen by Bell as needful of being demonstrated by simulation only ( assuming simulation means a full flight simulator ) rather than a flare to a power recovery demonstration? Engine response time or other engine/airframe interface consideration? |
The PT 6 is pretty darn reliable....but as anything mechanical, designed, built, maintained, and operated by Humans....it is not infallible.
By November 2015, 51,000 had been produced logged 400 million flight hours from 1963 to 2016, it is known for its reliability with an in-flight shutdown rate of 1 per 651,126 hours in 2016. |
So what the license requirements? Can it be flown on a ATPL H (EASA).
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Good point :)
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Your last line provokes a question as to why, therefore, it is now seen by Bell as needful of being demonstrated by simulation only ( assuming simulation means a full flight simulator ) rather than a flare to a power recovery demonstration. Certification for safe autorotation landing allows for limited damage to the aircraft to occur. My guess is that Leonardo does not want to cause any damage to their expensive and limited flight assets. |
Understand your response and concur, up to the point that you correctly refer to as a Leonardo decision. My curiosity is why, given the past flight test experience, why they choose not to demonstrate a maneuver that "would not require exceptional pilot skill ". The last phrase isn't FAA language, but a military requirements document just to be sure. Makes the point clear, though.
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Originally Posted by Medevac999
(Post 10287943)
So what the license requirements? Can it be flown on a ATPL H (EASA).
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If one holds an ATPL for both Multi-Engine Airplane and Helicopter....what credit will the authorities give for that when concocting the requirements for the Powered Lift qualification you reckon?
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Originally Posted by SASless
(Post 10288519)
If one holds an ATPL for both Multi-Engine Airplane and Helicopter....what credit will the authorities give for that when concocting the requirements for the Powered Lift qualification you reckon?
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Originally Posted by FH1100 Pilot
(Post 10287409)
do we take CH-53E's out, shut all three engines off and go to the ground? .
CTR: Certification for safe autorotation landing allows for limited damage to the aircraft to occur. My guess is that Leonardo does not want to cause any damage to their expensive and limited flight assets. SASless: If one holds an ATPL for both Multi-Engine Airplane and Helicopter....what credit will the authorities give for that when concocting the requirements for the Powered Lift qualification you reckon? |
I am thinking the 53E did EOL to a power recovery. due to there only being two prototypes.....and only one that was fully instrumented for flight test data purposes. Also....the 53E was a military protocol not a civilian certification. one thing for sure.....if the Brits ran a commercial Lunar Landing Program the Operator would require the Astonauts to pay for their own Type Rating!:E |
Hello Wrench 1, from the fellow who did the two S-92 auto’s. You only have to do one, successful data point that meets the FAA criteria. FAA Part 29 doesn’t require a set of maneuvers etc. In our case, we did the first one and it was fine, EXCEPT that in getting the N2’s close, in case I called for power at the last moment, Bob Spaulding nudged the throttles a bit too much and one of the engines N2 actually joined the Nr trace just at touchdown. That engine torque was zero on the data traces, so we could have successfully argued the point, but the first one went well enough* so we had a short conversation with the telemetry crew and decided it was easier to do another and not have a tenuous discussion. That probably also answers your second comment. *Knowing that we were going to do a full on auto sooner or later, I ended a lot of flights with a power recovery auto just to get comfortable with the speeds and flare point, pitch rate and max attitude. And of course on the day in question, we did a couple of power recoveries as a warm up for everyone involved. |
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