Henra:
Could you maybe enlighten me, what makes this so much more dangerous than two helicopters behind each other connected by a stick (Aka the Chinook)?
Henra, the side-by-side configuration of the tiltrotor is MUCH worse than the fore/aft/overlapping/intermeshing configuration of other types such as the Kaman 43 and Boeing 46/47 series. Here's why:
Very simply it has to do with the aerodynamics of two separate helicopter rotors. Unlike the rotors of the CH-46/47, the proprotors of a V-22 act completely individually.
Primarily, let's look at VRS. Let's say that one proprotor of a V-22 starts to go into VRS. It will roll to that side. What does the pilot do? Naturally he will apply a control input to counter the roll. In the tiltrotor this will increase the pitch of the proprotor on the side that is descending. As even the dumbest helicopter pilot knows, increasing collective pitch when beginning to encounter VRS is the exact
wrong thing to do.
Meanwhile, the proprotor on the side which is stil in "clean" air (or has not yet decided to go into VRS owing to the chaotic vagaries of Mother Nature) is still producing full lift. As the proprotor that's nibbling on VRS gets worse, the aircraft rolls over and attempts to go inverted. This can occur so quickly that the pilot might not even have time to recognize what's happening. (Chinooks and Sea Knights and Kaman Huskies do not exhibit this same tendency to flip over upside down. The fore/aft rotors do not have the moment-arm that the side-by-side proprotors of a V-22 do.)
Has this rolling-inverted-and-diving-for-the-ground thing ever happened? Yes. Google "Marana V-22 accident." Will this happen again? Yes. Currently there is no "VRS detector." I sure would love one in the helicopters I fly, but nobody has invented one yet. All the military and the manufacturer have done is put arbitrary and conservative limits on descent rates and airspeeds of the V-22...limits that will surely be violated in the heat of battle as the V-22 attempts to land in a "hot" or defended LZ. (I think the 2008 Afghanistan accident proved this; the crew was making a damn STRAIGHT-IN approach/landing and crashed.)
Tests were done that showed that the V-22 is "hard to get" into VRS. Sure, we understand. Even conventional helicopters are hard to deliberately put into VRS, because of the aforementioned chaotic vagaries of Mother Nature.
1) VRS does not always happen at exactly the same place and time. What can be a perfectly non-eventful steep, slow approach in a helicopter on one day can turn into a crash on another day with exactly the same conditions. You cannot predict with certainty when a rotor will go into VRS. If the conditions are right and all the holes in the Swiss Cheese line up- bam!
2) It's nice to do VRS testing up high, where there's plenty of altitude between you the pilot and earth. But where will VRS (or, in the case of the tiltrotor, A-VRS or "Asymmetrical VRS") happen? Correct...down low where there very likely will be little time and/or altitude to recognize and recover.
V-22 proponents swear to us on a stack of Bibles that A-VRS will never happen again because...well...because we know about it now! Ohhhhh, so simple! Why didn't I think of that! All it takes is being aware of a problem and...
voila!...the problem goes away!
Oh wait. Helicopter still crash from VRS (or the related excuse, "settling with power") even though we know about it in helicopters too. VRS/SWP happens down low, and it usually happens so fast as to catch even a good pilot by surprise. What hope does a task-saturated V-22 pilot have who's trying to land his machine in a nasty place and maybe downwind? The Marana crash was during a downwind approach, and the hapless Major Luce's first, controversial Afghanistan crash was also at the bottom of a downwind landing. So don't tell me that V-22 crews always, religiously, without fail land into the wind IN THE REAL WORLD. Obviously they don't.
So the side-by-side...the two-helicopters-connected-by-a-stick configuration of the tiltrotor is why I feel that it is a defective, deficient design.
That is why I feel that they are unsafe...that there will be more crashes that are just assigned to "Pilot Error." And that is what will ultimately kill the tiltrotor: Sooner or later people will have to admit that I'm right.