Here we go again, FH and the A-VRS boogie man. Haven't you been sufficiently slapped down in this very thread over and over enough? As stated at least a dozen times, A-VRS is as much of a problem as say, mast bumping. You understand the envelope, you avoid the envelope, and it just so happens that in the V22 if you are vigilant when you depart envelope, you can get out of it.
from ospreydriver
It's not a weakness of the design though. The V-22 is LESS susceptible to VRS than normal rotorcraft. The rate of descent limitations given for the V-22 mirror those given for almost every other helo--no more than 800fpm at less than 40 knots. Those are the same limits that I was told in the TH-57(B206) and the same as the CH-46E. They are precautionary, and based more upon the limitations of pitot-static airspeed instruments than anything else. Stay above those, and you'll definitely stay out of VRS.
To enter VRS in the V-22, you have to be descending at more than 2000 fpm and nearly vertical. That's crazy fast, and easily avoided. Should you somehow blow through that, the V-22 has an out that no other rotorcraft does--tilting the nacelles.
Granted, the consequences of VRS are worse in a V-22 than a helo, but seeing as it's harder to enter VRS and easier to get out of it, I think that concern is largely mitigated.
I think the cost and reliability criticisms of the V-22 are valid, though both are improving over time. As far as performance, though, nothing else holds a candle to it.
and my personal favorite, picking your last dead horse A-VRS argument apart point by point:
What becomes abundantly clear reading FH1100s post is that he does not understand VRS(or A-VRS) nor has he taken the time to actually read and study the literature available about it. It's also obvious that FH1100 has absolutely zero comprehension of how military operations are flown, how pilots are trained and how crews are scheduled, how tactics are developed and how through training and tactics approach profiles etc. address issues such as VRS (yes A-VRS). Furthermore it's obvious that FH1100 has no concept of how tilt rotors are flown however he has come to his own conclusions based what he has read on blogs and pretty much nothing more. If only he would choose to pontificate about something he knew about, like being a raconteur.
FH, in your first post you asked
"Just HOW is the aircraft different from the one that Majors Brow and Gruber flew in April of 2000? Does it have a reliable VRS indicator now? You know, like the stall-warning horn in an airplane, that can physically sense when a wing is at a critical angle of attack?"
This implies that if it had such a device it would be safer, well it does but now that is not sufficient for you.* No it doesn't have an A-VRS sensor, but if one avoids VRS then one will avoid A-VRS. No it doesn’t sense how close a proprotor is to VRS but provides the pilot both visual and aural cues of approaching limits. Remember that no device can ultimately keep a pilot from exceeding limits. If that is your design criteria then I suggest that we ground every aircraft out there because everyone of them has limits that if exceeded will result in a fatal mishap.
*
In your second post you state:
'However I have never accidentally or inadvertently stalled an airplane. Why?'
So you triggered the stall warning then you inadvertently got too slow and if it weren't for the stall warning you would have stalled.
‘Because the stall-warning horn gave me sufficient warning that I was approaching a critical angle of attack.’
You admit that warnings work! If it worked for you why won't the VRS warning work for a V-22? They indeed have a warning device installed and there have been no further VRS(or A-VRS) mishaps since its installation. You should be happy. Apparently it works. Case closed. Oh wait, you always have a straw man argument to prove why it won't. Sorry, I can't counter those as they are pretty much devoid of reality. Will another V-22 crash at some point due to A-VRS? Probably. Will another fixed wing aircraft crash due to stall? Probably. Will another Biz jet run off a runway because the brakes failed? Probably. Should I continue?
But then you go and contradict yourself by implying that stall warnings don't work, stating the Airbus accident.* In fact you disrespectfully state:
'THREE pilots in that cockpit, stall-warning going off and not ONE of those geniuses suggested lowering the nose and, you know, flying out of the stall.'
Actually I believe if you were to read that report again you would find the facts to be slightly different. However are you suggesting the Airbus a dangerous aircraft with a fatal flaw and should be grounded because pilots failed to react properly?
‘The PFD and audible sink rate warnings are, in my opinion insufficient. I think that in practice, when the sh*t hits the fan, those warnings will be summarily ignored by V-22 pilots just like the stall-warning alert was ignored 75 times by the crew of AF447’
Yet you didn’t ignore the stall warning you received? I wonder why it worked for you but will fail for V-22 pilots? Maybe you’re just a better pilot then they are. No, apparently you think your 206 can do aerobatics (previous post) because your RFM doesn’t say it can’t, you’ve flown yourself into VRS and you apparently need the stall warning to keep you from stalling, I’d say you are about average like the rest of us.
So FH do you think stall warnings work or don't they? Your argument is a bit confusing since you take both sides.
‘Because they were confused. But that will never happen to pilots in combat, will it?’
Yes it will. They will get confused in the V-22 and make mistakes, sometimes fatal. Just as pilots have gotten confused in H-1s and made fatal mistakes. Just as they have CH-53s and made fatal mistakes. What’s your point? That they will only make mistakes in the V-22 or that only mistakes in the V-22 will be fatal?
“Uhh, didn't they actually do just that? Why do you think the military flies UH-60's now and not UH-1Ns? Why are they developing the UH-1Y? Seems to me that if the 2-blade system was so great we'd still be using them. But what do I know...'
That was completely ignorant. Payload, range, speed and other factors. Not safety. The two bladed rotor is perfectly safe but there are gains to be made with more blades. In fact don’t you fly a 206? Is it unsafe? Are you afraid to fly it because it only has two blades? What’s the safety record of the two bladed rotor system?
“I've never said the V-22 is more susceptible to VRS than a helicopter. I say the V-22 is more susceptible to A-VRS than a helicopter. ASYMMETRIC VRS: One proprotor goes into it while the other one does not. Why do some of you guys keep denying the importance of this?”
Thank you for the explanation but unlike you I’ve actually studied the issue. It would be nice if you did the same. Nobody denies the importance of it, we just understand it, unlike you.
'The article that 21st Century posted by Lt. Col. Gross tells us that the V-22 crew now gets a "SINK!" warning on their PFD and an audible warning if the a/s drops below 40 knots and the RoD gets to 800 fpm. Great. Those are pretty conservative parameters.'
The same exact parameters that apply to all rotary wing aircraft, not just tiltrotors. Sorry if you don’t like it, but it’s true.
“Wait a minute. If an equivalent helicopter got into VRS at the same altitude as Majors Brow and Gruber, the helicopter would've settled vertically. If it hit the ground it would have done so upright, on its landing gear...not inverted like the V-22 did. See, for those of you who don't know, it's pretty hard for a helicopter to get into A-VRS.”
2400 fpm is 40 ft/sec. If a 53 were at 285 agl at at 2400 fpm ROD and tried to recover from VRS, if the correct action was taken the pilot would lower the collective and push the nose over, both of which would increase the ROD so it would impact at at least 40ft/sec. I’m sure there is someone on here who can tell us what would happen to CH-53E if it settled vertically and upright onto the tarmac at 40 ft/sec. I’m going to guess that 40ft/sec is well beyond where the gear would yield and the OEM guarantees an chance of survivability. But I could be wrong. You are correct FH, the V-22 in A-VRS would roll over, the 53 wouldn’t. 21 century is right in that the end result would have been the same.
And hard test data, quoted over and over ad nauseum in this humble thread. I can only assume FH has chosen not to read it.
http://legacy.vtol.org/pdf/test-60.pdf
Honestly, have you ever actually spoken to Opsrey pilots? I have on many occasions at airshows, and every single last one of them enthusiastically loves the airplane. It's no show.