Retreating Blade stall

[ame]

Is it really this aggressive?

I'm also not noticing any tendency for the aircraft to nose up during the stall. It should according to countless number of articles on the subject. (FAA helicopter handbook as one example.) Or does the Gazelle's rotor have some sort of counter to that?

I understand that the module is not finished yet, but i'm not sure this is a bug or not.

Is it really this aggressive?

Never seen real life footage, seeing as pilots probably aren't too eager to provide actual examples. :D

But I guess it actually is quite aggressive.

I'm also not noticing any tendency for the aircraft to nose up during the stall.

Good point, I'd have expected that as well. I thought I saw that in your other video, but here it's practically non-existent.

In the first example in your current video, you write "Trying to correct, probably too much input". How would you correct? Since about half of the rotor disc is currently stalled, you only have the other half to work with. Which means that it doesn't matter a whole lot what kind of input you provide after entering the condition.

In example #2, I guess you made the correct input while enough of the retreating blades were still not stalled, so the input was applied in time to avert certain death.

A real life Apache pilot in training wrote about it, I'll just quote it because it's very much to the point, even though the Apache is obviously not a Gazelle:

The problem is that the helicopter pitches and rolls left almost instantaneously. So yes it will slow down technically but you will also likely be in an extreme left dive if not inverted. The lift produced by the right side is so great that without the left side being able to compensate it has the force to flip the aircraft over.

 

We are taught to slow down the second you even think you are encountering retreating blade stall. Usually by the time it actually happens it is too late to do anything about it. I don't personally know of anyone who has recovered the aircraft from it once it has pitched up and rolled left. I have heard plenty of stories of people who have unfortunately died from it. Since the only real way to get into it is to be in a pretty steep dive you must think of the flight profile at the time. The aircraft is already in a steep dive now imagine being in a steep dive then getting flipped upside down then trying to flip right side up and pull up at those high airspeeds without destroying the aircraft. Helos aren't nearly as maneuverable as jets in that aspect.

 

I think you may be thinking that the pitch up and roll happens slowly, however, it does not. It happens almost as fast as a fighter jet doing a barrel roll.

I wouldn't call it a bug. The FM works as it should. But both of you are right. It should also nose-up a bit. But the greater effect is the flip-over to right or left, depending on a clockwise, or counter-clockwise rotorsystem. Maybe due to the hard dive (nose down attitude) the nose-up effect isn't encountered that much.

I think you may be thinking that the pitch up and roll happens slowly, however, it does not. It happens almost as fast as a fighter jet doing a barrel roll.

Oh my god, that's terrifying.

this was an Australian BK 117 Lost 4000 Ft alt before recovery.

http://aerossurance.com/helicopters/retreating-blade-stall/