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One thing to keep in mind is that these were not only new technology, they were new concepts in aviation.

Even though there had been prototypes many years before that had achieved some form of vertical takeoff and landing, they were strictly prototypes and never taken to production.

So this was an entirely new form of aviation. They were not helicopters, whose flight characteristics were well understood. This was something new, and it had unusual characteristics all its own.

Specifically, they found out the hard way that this particular form of aircraft was far more susceptible to an unusual state called Vortex Ring State. It was known in helicopters, but was far easier to identify and get out of. What happens is, when a helicopter descends vertically too quickly, it causes the rotors to lose lift, and the aircraft rate of descent increases alarmingly.

Traditional helicopter pilots know where in the flight envelope they would encounter this, and they are all trained on how to get out of it. Generally, they know how to avoid it, and stay ahead of the eight ball to do so. If they DO get into it, they know how to get out of it. It is standard training, if I understand it correctly.

In the Osprey, an entirely new form of aircraft, there were two problems they were generally unaware of: where in the flight envelope they would encounter it, and how they could get out of it.

It turned out, they were FAR more vulnerable to it than a traditional rotorcraft, they didn’t have a handle on where they would encounter it, and they had no idea how to get out of it. (IIRC, they just assumed that their training on vortex ring state as helicopter pilots was adequate, that they would see it the same way in the same place, and the technique to get out of it was the same as well.

It took multiple Class A mishaps (loss of life/platform) before they got a handle on it...they had at least one major mishap involving vortex ring state (dropping to the ground too fast and losing lift) that killed an entire compliment of men aboard (I think three crew and 24 Marines) and additional accidents that destroyed the aircraft without that loss of life, all due to ring vortex state.

(IIRC, they did have another Osprey fully loaded with men that crashed killing all aboard, but it was due to an engine fire not ring vortex state...an accident caused by the complexity of the machine, flawed construction, and poor maintenance procedures.

Anyway, with vortex ring state, they adjusted the software, changed the instrumentation, and trained the pilots. The aircraft is still susceptible to it, but they know how to avoid it and recover from it.

It is still a complicated machine require higher maintenance, but it is also far more capable too.