reported On Vortex Ring State from active Mi-8 instructor

[Hiob]

What? Why.

That wasn't meant for trolling.

 

Tell me, how exact does the haptic feedback of a real aircraft translates into DCS? It doesn't - like at all...

How does the muscle memory for the controls of a real aircraft transfer to DCS? near to not at all....

 

who's the troll here?

 

not to mention:

- perception of depth

- peripheral vision

...

Edited April 14, 2021 by Hiob

[cw4ogden]

@Hiobwhat exactly have you brought to the discussion other then summary rejection of my points, many you obviously didn’t read?

 

what’s your role here other than quoting your extensive YouTube viewing history?

 

[Hiob]

That's the point.

You throw in a thesis and I reject it. Therefore I dare to oppose to some of your arguments.

 

If you can't handle that - you shouldn't throw out your theory in a forum...

[cw4ogden]

3 hours ago, Hiob said:

What? Why.

That wasn't meant for trolling.

 

Tell me, how exact does the haptic feedback of a real aircraft translates into DCS? It doesn't - like at all...

How does the muscle memory for the controls of a real aircraft transfer to DCS? near to not at all....

 

who's the troll here?

 

not to mention:

- perception of depth

- peripheral vision

...

 

The @Hiobwhat exactly have you brought to the discussion other then summary rejection of my points, many you obviously didn’t read?

 

what’s your role here other than quoting your extensive YouTube viewing history?

3 hours ago, Hiob said:

What? Why.

That wasn't meant for trolling.

 

Tell me, how exact does the haptic feedback of a real aircraft translates into DCS? It doesn't - like at all...

How does the muscle memory for the controls of a real aircraft transfer to DCS? near to not at all....

 

who's the troll here?

 

not to mention:

- perception of depth

- peripheral vision

...

 

Haptic feedback is copout argument for not fixing a bug.

 

to address your newest points.  I have no depth of vision wearing nvg I have no peripheral wearing nvgs.

 

pilots learn to adapt to their circumstances.  
 

And guess what else we spend a lot of time doing as actual pilots: flying simulators.

 

And your assertion there is no correlation between sims and real life skills is hogwash you read somewhere.  It’s not factual.  The very reason flight simulation exists is that correlation.

In my case, the qualifications I speak to as relevant are IN addition to the actual pilot stuff, is lead test and development and certification of an actual heavy lift cargo simulator.  Located in Daleville, Alabama run by a company called L3.  
 

Stop being a naysayer and get on board fixing the thing you’re a fan of.  

 

 

Edited April 14, 2021 by cw4ogden

[Fri13]

6 hours ago, Hiob said:

Those are exactly my two concerns.

First, pilots opinions are biased because they heavily rely on memories and „feels“. And the latter can‘t be reproduced by a sim as I mentioned.

 

If someone would ask that what person needs to do to drive a simple car from home to work, it is very difficult task to actually explain in detail that how much they need to turn the wheel or how much they need to push pedals or what gears they needed to switch in what order and at what speeds. 

Even if the person has drove that same route weekly for last 20-30 years.

 

Human mind is very fragile and forgets many things, and it is very easily filled with false memories, information and doubts with simple suggestions. 

That is why these days ED should use a simple custom made "blackbox" to register all the aircraft movements if not just from cockpit, then from outside having them mounted there. They literally are gopro size devices that measure all accelerations and so on all G forces, roll rates etc. They can be used to measure with camera recording from cockpit instruments to check some values. Record the control devices positions and all movements etc.  

[cw4ogden]

3 hours ago, Hiob said:

That's the point.

You throw in a thesis and I reject it. Therefore I dare to oppose to some of your arguments.

 

If you can't handle that - you shouldn't throw out your theory in a forum...

I didn’t throw out a thesis, I made an observation based on many many factors all of which you, as you say reject summarily, without offer anything substantive to the conversation.  
 

You can not get into VRS in the conditions you can in DCS, that is my observation.  It’s manifestly impossible in probably any helicopter because the aerodynamics don’t work the way the DCS hip teaches you that you have to fly.

 

Congratulations, and welcome the world of bad habit transfer if you ever get the chance to be an Mi-8 pilot.  

 

You have lots of hypothesis and theories on why my observation is wrong.  I merely have an observation.  I have hypothesis for why the observation might be happening, but you're not acknowledging my observation as even valid much less getting to my hypotheses.

 

 

 

 

Edited April 14, 2021 by cw4ogden

[cw4ogden]

@HiobIn no world does it make sense to pit your extensive YouTube viewing history against my credentials and call it a draw because you just won’t come around to reason.  
 

And asserting pilots are a poor resource for determining a simulation’s authenticity is one of the stupidest things on its face I’ve ever seen asserted. 
 

Who then do you put the task to?

 

if you’d devoted 1/3 of your energies wasting my time to looking into my assertions and observations you’d have likely learned something.  
 

but here we are, you steadfast in your life experience endowed sense of authority and my absolute inability to crack your severe case of Dunning Kruger syndrome.

 

I’m out.  I don’t need the aggravation arguing with you brings me.  

Edited April 14, 2021 by cw4ogden

[cw4ogden]

A more naive version of me might have thought I’d be welcomed as someone with authority finally  throwing the bullshit flag on a known issue, and prepared to make a case on your behalf, with evidence both tangible and circumstantial to make your sim more accurate.

 

silly me.  

[cw4ogden]

1 hour ago, Fri13 said:

 

If someone would ask that what person needs to do to drive a simple car from home to work, it is very difficult task to actually explain in detail that how much they need to turn the wheel or how much they need to push pedals or what gears they needed to switch in what order and at what speeds. 

Even if the person has drove that same route weekly for last 20-30 years.

 

Human mind is very fragile and forgets many things, and it is very easily filled with false memories, information and doubts with simple suggestions. 

That is why these days ED should use a simple custom made "blackbox" to register all the aircraft movements if not just from cockpit, then from outside having them mounted there. They literally are gopro size devices that measure all accelerations and so on all G forces, roll rates etc. They can be used to measure with camera recording from cockpit instruments to check some values. Record the control devices positions and all movements etc.  

I’d counter your first argument with training.  When a line pilot arrives at the instructor pilot course (us army) they can fly like champs.  But you ask them to demonstrate a VMC takeoff pattern and approach, like they are the instructor telling me the “student” what to do, they fall apart.  
 

Until you are trained to do it, you can’t fly and give instruction on a task at the same time.  
 

As a matter of personal insight learned as an instructor training new instructor pilots, what you’d call situational awareness, is nothing more than division of attention and prioritization of tasks.

 

No one can do two things at a time with the one fabulous caveat - if you can do one, or the other, or better yet both without thinking about it.  The way you drive without thinking about it.
 

A new instructor pilot cannot talk and fly at the same time usually.  both go to varying degrees of shit depending on personal aptitude and preparation, ie how long did you rehearse you’re “MOI” or method of instruction.  Prescripted sentences like “to begin the VMC takeoff, apply smooth collective input while simultaneously achieving a positive rate of climb and and accelerative attitude” while they are demonstrating the maneuver. 

 

With time, they can speak, but their flying looks like crap until they can either fly or talk without thinking about it. 
 

that’s all situation awareness is, diverting your attention amongst many things and keeping track of which will kill you first.  Any task you can do without thinking is gravy on the potatoes.
 

Nor everyone can do this job.  A significant portion bordering on half are born straight out of training to be lifelong co-pilots. 
 

Not everyone makes pilot in command, fewer still become instructors, and fewer still the instructor for the instructor pilots.   

 

The sentiment I’m getting is it’s like flying is some sort of cowboy shit, and pilots are stupid stick wigglers, and that’s just not the case.  
 

I don’t claim to be an expert lightly and for much beyond the scope of what’s being discussed here.  But for VRS in a medium lift cargo helicopter, I am an expert. 
 

 

Edited April 14, 2021 by cw4ogden

[cw4ogden]

I'll also claim expertise on flying without haptic feedback and evaluating accuracy of flight modeling because I have done that, professionally.  There are plenty of good arguments like why tempt fate potentially breaking a great module, but haptic feedback is a lousy one, as is saying pilot's are unreliable reporters of accuracy.  There's truth to that argument, but not to the degree expressed in this discussion.  And not for something so flagrantly obvious to any pilot with an ounce of time; it's why this topic is the dead horse we are beating.  

Dead horse arguments only happen when one side is intractable in their belief the horse is even a horse. 

[cow_art]

Disclaimer: I am a gamer and have never piloted a real helicopter. I have absolutely no opinion on the realism of VRS in DCS.

 

I just wanted to say that I find this discussion and your opinion as an expert extremely interesting. I started playing whirlybird games with Gunship back in the 1990s, and it never ceases to amaze me what a long way simulator games have come. I mean, back in the day I was happy to control an aircraft that "somehow" behaved like a helicopter (although in retrospect it absolutely didn't ). And now we are at a stage where real pilots discuss if some subtlety of flight dynamics are slightly over- or under-modeled compared to the real thing. For me as a gamer and aviation-nerd that's just amazing

 

I have to admit the argument "if it was this easy to kill yourself with the Mi-8 there probably would be more cautionary tales" does have a lot of merit. Hell, there is an audio warning if one of the (redundant) generators fails for a second. Wouldn't there also be some sort of warning if we are close to the part of the flight envelope that spells "certain death"?

 

Edited April 14, 2021 by cow_art

[cw4ogden]

21 minutes ago, cow_art said:

Disclaimer: I am a gamer and have never piloted a real helicopter. I have absolutely no opinion on the realism of VRS in DCS.

 

I just wanted to say that I find this discussion and your opinion as an expert extremely interesting. I started playing whirlybird games with Gunship! back in the 1990s, and it never ceases to amaze me what a long way simulator games have come. I mean, back in the day I was happy to control an aircraft that "somehow" behaved like a helicopter (although in retrospect it absolutely didn't ). And now we are at a stage where real pilots discuss if some subtlety of flight dynamics are slightly over- or under-modeled compared to the real thing. For me as a gamer and aviation-nerd that's just amazing

 

I have to admit the argument "if it was this easy to kill yourself with the Mi-8 there probably would be more cautionary tales" does have a lot of merit. Hell, there is an audio warning if one of the (redundant) generators fails for a second. Wouldn't there also be some sort of warning if we are close to the part of the flight envelope that spells "certain death"?

 

Hey thanks for the post.  I'm in need or moral support.

Additionally, there would absolutely be VRS pilot charts specific to weigh configurations and density altitudes that anyone arguing against should be able to find quite easily.  

All this back and forth aside.  The VRS modelling is close.  It's not too far off.  But where it is off, it is off in a big way if I can encounter it under normal flight maneuvers.

Dynamic rollover, settling with insufficient power, Loss of tail rotor effectiveness (not implemented I believe), ground resonance, retreating blade stall, blade compressibility, and vortex ring state: None of these are unknown quantities. 

We pour over charts before every takeoff, mostly nowadays by computer which is sad a bit in and of itself, because you really lose the context of the numbers you generate.  

There is no conceivable way, in my self proclaimed expert opinion, they can have VRS right as it currently is modeled.

Now invariably someone will counter with the charts exist.  And they do.  At the test-pilot and engineering level.  And the fact they are not generated for the pilot in any Mi-8 specific form yet discovered by the forum army, we can assume, and have confirmation from my source, it doesn't fly significantly different than any other helicopter with regards to VRS.  

And I'm saying as a a guy with extensive time in a similar bird, extensive time in simulation community both professional and as a hobbiest, training the exact flight condition to instructor pilot candidates, because you don't get the demonstration as part of any curriculum I just wouldn't sign you off to be an Instructor without having felt it personally.  Because this is my bailiwick and a pet peeve of mine personally within that bailiwick I can say without hesitation, something is very off with VRS.

I want to check approach angles and run some more tests, but it is wrong, close, but wrong enough to be considered a serious bug in my opinion.  There's no way in hell I'd certify this flight model as is, and it's only because of the valiant, yet unfinished attempt at modeling a complex aerodynamic phenomenon that is VRS.  VRS is by and large not part of any pilot's thought process, except for when operating under very specific flight parameters.

It is deadly, it is not common.  

Edited April 14, 2021 by cw4ogden

[Fri13]

48 minutes ago, cw4ogden said:

Until you are trained to do it, you can’t fly and give instruction on a task at the same time.  

As a matter of personal insight learned as an instructor training new instructor pilots, what you’d call situational awareness, is nothing more than division of attention and prioritization of tasks.

 

Exactly. You can train and become expert in things, but it doesn't mean that everyone can do it, even with training.

 

48 minutes ago, cw4ogden said:

No one can do two things at a time with the one fabulous caveat - if you can do one, or the other, or better yet both without thinking about it.  The way you drive without thinking about it.

 

Actually there are people who can do it. About 2% of the population can do two simultaneous tasks excellent manner. But that is it, very minor amount of population.

Like driving a car at begin is that you concentrate for everything and you need to alternate concentration from one task to another. But in time it becomes natural thing to do, until you hit to point where you are in situation that is not experienced. Like a emergency situation. In a high attention demanding jobs you can improve the performance by training, but only up to a point when your limitations are the end.

 

48 minutes ago, cw4ogden said:

A new instructor pilot cannot talk and fly at the same time usually.  both go to varying degrees of shit depending on personal aptitude and preparation, ie how long did you rehearse you’re “MOI” or method of instruction.  Prescripted sentences like “to begin the VMC takeoff, apply smooth collective input while simultaneously achieving a positive rate of climb and and accelerative attitude” while they are demonstrating the maneuver. 

 

That has been demonstrated to be just a way of thinking that one can learn very quickly, once they itself know what is going to happen. You can get average person to describe properly the process of X even when they do it at first time while they are doing it, but it is as well question that how accurately they need to describe things. It can be trained in daily life in normal tasks to get to that state of mind. 

 

48 minutes ago, cw4ogden said:

With time, they can speak, but their flying looks like crap until they can either fly or talk without thinking about it. 

 

That is the interesting part in the experience that how people's skills get better via training. You see them do something first time and then they get better with just few repeats. Doesn't work so easily for everyone, but most get to it. But when it comes to very complex phases, let's say to perform a over 100 proper functions in correct order and timing, it becomes very complex. And there are really just handful of people who can do that, who can example listen a song first time in their life and repeat it. 

 

48 minutes ago, cw4ogden said:

that’s all situation awareness is, diverting your attention amongst many things and keeping track of which will kill you first.  Any task you can do without thinking is gravy on the potatoes.

 

Actually tasks that you do without thinking are likely those that will kill you. That is the most dangerous part of the in daily live. The mind being somewhere else because body goes by automation for something that has been trained and trained to level. The requirement to concentrate for the doing is challenging. 

 

48 minutes ago, cw4ogden said:

Nor everyone can do this job.  A significant portion bordering on half are born straight out of training to be lifelong co-pilots. 

 

Yes, it is surprising percentage that how many drops from being in the specific position. That is as well reason why it is wrong to say "Everyone has a change to get where they want to be in their lives" as it is totally wrong. 

 

48 minutes ago, cw4ogden said:

Not everyone makes pilot in command, fewer still become instructors, and fewer still the instructor for the instructor pilots.   

 

And interesting part is, that even those will not train or experience everything even at the basic level as they don't need to. 

 

48 minutes ago, cw4ogden said:

The sentiment I’m getting is it’s like flying is some sort of cowboy shit, and pilots are stupid stick wigglers, and that’s just not the case.  

 

Well, let me put it this way.... When you are at the war and you have pilots dying all around you. You lower your standards. There is no any other way. The idea that you can just have a handful of extremely highly trained pilots to win the war is just wrong. Unless of course you can have thousands and thousands of such people.

That is why even today militaries fund a lot of research projects that sounds like a Sci-Fi, where one could transfer one's experiences to a another person. Almost instant training. From years you could cut to days or even hours. As there is a genetic memory, and if it could be found how to copy and implement memories... 

 

48 minutes ago, cw4ogden said:

I don’t claim to be an expert lightly and for much beyond the scope of what’s being discussed here.  But for VRS in a medium lift cargo helicopter, I am an expert. 

 

I just wanted to point out that regardless what level pilots there are, there are majority still that can not transfer their knowledge to a simulator without doing proper questioning and proper context and environment to give the pilot a better understanding that what is the goal of the simulator to be.

Like you can't have a helicopter pilot have same experience of flying with a just joypad and display. They can read the instruments and if some remembers things correctly then know if some things are going wrong like RPM is too high or aircraft doesn't stop at proper time based to instrument. But that is again more about why giving different testing environment gives different results. 

 

Pilots are humans. They forget things and they remember things wrong etc just like anyone else.

Military has done a lot of studies and research for this as well among civilians for decades, and only in the decade or two has them started to be taken seriously and applied to the practice. The problem is as well that more you recall the memory, more you rewrite it. And when you learn even how to do it, you can wipe your own memory of events.

These are not simple topics, but for comparing it analyzing and understanding VRS that is simple topic, it is still required to be more scientific and tested than memory based feeling.

 

[cw4ogden]

25 minutes ago, Fri13 said:

Pilots are humans. They forget things and they remember things wrong etc just like anyone else.

Military has done a lot of studies and research for this as well among civilians for decades, and only in the decade or two has them started to be taken seriously and applied to the practice. The problem is as well that more you recall the memory, more you rewrite it. And when you learn even how to do it, you can wipe your own memory of events.

These are not simple topics, but for comparing it analyzing and understanding VRS that is simple topic, it is still required to be more scientific and tested than memory based feeling.

 

Sure, but that only takes a swing at me the observer.  It doesn't account for the multitude of other anecdotal evidence.  

You can not minimize the importance the pilot plays in simulation development, or you do it at least at your peril.  And here we are.  With a glaring flaw in the flight model, and you want me to chock it up to my memory is fuzzy.  Maybe so.  But all other evidence brought forth indicates my observation is correct.  

No specific MI-8 charts for VRS 
No long list of lessons written in the blood by dead mi-8 crews

No credible people arguing "hey, actually it is that bad."

No hint of it being vested in reality from a guy who flew a similiar aircraft and took it on himself to say, that's not enough, ask a real real expert.  Who confirmed VRS doesn't plague the Mi-8 community the way it plagues the DCS community. 

It should be manifestly impossbile to get into VRS with any approach angle less than about 30 degrees, which is a very steep approach.  Yet we have a forum with post after post of "why do I die when I try to do a simple landing"?

Say you like it, say it's part of the DCS experience, just don't say it's representative of reality because it isn't for the many many reasons I've cited.

[Fri13]

45 minutes ago, cw4ogden said:

Sure, but that only takes a swing at me the observer.  It doesn't account for the multitude of other anecdotal evidence.  

 

No matter count of anecdotal evidences there are, they might not be true. That is the problem with them. 

 

Quote

You can not minimize the importance the pilot plays in simulation development, or you do it at least at your peril.  And here we are.  With a glaring flaw in the flight model, and you want me to chock it up to my memory is fuzzy.  Maybe so.  But all other evidence brought forth indicates my observation is correct.  

 

Pilots feedback is important, and it can be utilized where the measurements or lack of information creates a oddity. But it can't be used as primary source over technical evidence and material. Like people can experience a feeling that a control device shakes, while there is no measurable shaking happening.

And I am not choking anything that memory is fuzzy, just pointing out that human memory is fragile, and it requires other technical evidence and such to be presented.

This is not against you, this is against the idea that pilots are critical or important parts of the evidence, as the fact just is that human memory can not be trusted.

 

Quote

No specific MI-8 charts for VRS 
No long list of lessons written in the blood by dead mi-8 crews

No credible people arguing "hey, actually it is that bad."

No hint of it being vested in reality from a guy who flew a similiar aircraft and took it on himself to say, that's not enough, ask a real real expert.  Who confirmed VRS doesn't plague the Mi-8 community the way it plagues the DCS community. 

 

There I lost Your points, but it is OK. I don't deny them.

 

Quote

It should be manifestly impossbile to get into VRS with any approach angle less than about 30 degrees, which is a very steep approach.  Yet we have a forum with post after post of "why do I die when I try to do a simple landing"?

 

Okay, that is the point. Sorry, didn't connect the dots in the earlier discussion as didn't read to the end.

I read that part about the diagram of the VRS zone and first I was little stunned that how I don't understand it as I was constantly reading the X axis as "vertical speed" and 0, 1, 2, 3 meters made me scratch head that how can a helicopter sink to VRS at 0-1 m/s vertical speed at higher angle than 30 degree...

Until after a minute I read it correctly that it was a horizontal air speed... 

 

And the discussion about 30 degree being very deep angle, it is.

In a Mi-8MTv2 in a DCS, I might have dropped to VRS maybe few times at the first flights. After that I have might gotten to VRS when I have made ridiculous and extreme landing scenarios that would never in reality happen, like having full bomb load on the one side of the helicopter and other side being empty, landing in a crazy 16 m/s wind and testing the flight modeling for various approach angles and speeds. 

But maybe it is as well about my first flight methods, where usually I put the new modules airframes to extreme tests to just brake them and challenge them. Find the limits and character by the feeling/touch. As then I know better what to avoid before even starting to look a proper values. 

 

For a normal flight I don't end to VRS as it feels easy to avoid.

But if that 30 degree part etc is proper, then sure, it should be impossible to get into VRS in such approach angles. 

 

I have seen only few videos of the Mi-8/Mi-17 ending to VRS, and they have been fairly dangerous looking ones. Again difficulty to say much without more accurate technical data.

 

Edit: I played Mi-8MTv2 last time on the 2D years ago. Since getting the Rift CV1 and going to full VR and building the proper helicopter controls and all, the Mi-8MTv2 flight experience has been totally different. All the helicopters are completely different to fly in VR with proper controls than it is on throttle/short joystick/no pedals or controllers on table and looking game via display. I believe I would be terrible with any helicopter in DCS if I would need to play it from table and display. 

 

Quote

Say you like it, say it's part of the DCS experience, just don't say it's representative of reality because it isn't for the many many reasons I've cited.

 

That I didn't say that it would not be representive or it would be about reality.

 

Edited April 14, 2021 by Fri13

[cw4ogden]

@Fri13 I want to run a couple tests once DCS finishes updating.  I'm going to try to find the actual source of what feels wrong and see if I can provide an example of it.  

I take your points, and I'd reiterate I'm not saying it's off by a lot.  It needs a tweak.  Not an entire rework.  The coding is good for VRS, I like how they modeled it.  I just question it's accuracy based the fact everyone has to learn how to fly the DCS mi-8.  Everyone qualifies their statement with, I had trouble with VRS at first, but I learned to live deal with it.  

The actual reality is the vast majority of people never experience VRS.  Not intentionally, nor inadvertently.  VRS accidents are rare.  They happen, but they are rare.

And DCS doesn't feel wrong, necessarily.  Just wrong for the conditions, lightly loaded aircraft operating near sea level, it's far too aggressive.  The current flight model is what I would expect to feel operating at high altitude near max gross weight.  Conditions where you are on the edge of the phenomenon.  Not sea level, not lightly loaded and not doing a simple approach to landing.

[AlphaOneSix]

4 hours ago, cw4ogden said:

A more naive version of me might have thought I’d be welcomed as someone with authority finally  throwing the bullshit flag on a known issue, and prepared to make a case on your behalf, with evidence both tangible and circumstantial to make your sim more accurate.

 

silly me.  

Yeah I hit that point long ago. I still post every now and then, but I gave up trying to make the sim better, I just talk about the real thing and let the virtual pilots figure out the rest on their own. Sometimes my knowledge is helpful to some, and for that, I'm happy enough.

 

I just spent today, for example, making a refueling chart that shows, based on how much fuel you actually put into the aircraft, what the cockpit gauge will read on the ground when the aircraft is parked. (Result: The only time fuel added equals fuel on the gauge, on the ground, is when the tank is nearly full...the emptier it is, the more inaccurate the cockpit gauge is. I don't remember if that's modeled in the game or not.)

 

At any rate, your insight is always welcome here, even if it is from a 47 guy. (I kid, I kid!)

[cw4ogden]

@AlphaOneSixI’d welcome a better qualified expert if you know one.  I don’t write off the possibility it’s correct, but you really could

Certify the DCS hip model for flight in real life without serious control measures that would be reflected in real world literature and real world history / real world training procedure etc. I can’t find.   
 

I’m having a hard time putting my finger on what’s off or feels off, other than to say it feels far too susceptible to it.  Maybe it’s a simism, but I’ve flown dozens of helo sims and had aircraft in crazy flight profiles that ride the edge of the flight envelope for good reason and I’ve never had a problem with VRS the way here, it can render you a smoking hole in seconds.  

 

Nor do I know of anyone who has.  

 

I welcome evidence to the contrary.  My intent isn’t to die holding a hill, but also to not have people see helicopter flying as an inherently unsafe.  
 

I don’t think the mi-8, if it flew like it did here could be certified.  Yes it’s Russian, and they are different than us but we’d see a string of these fatalities if it was accurate.  

[AlphaOneSix]

The various Mi-8/17 flight manuals I have all say that in order to avoid VRS, do not exceed a descent rate of 4 m/s below 40 km/hr, and do not exceed a descent rate of 3 m/s in a vertical descent.

 

vrs.png (994×155) (halo5.net)

 

Oddly, I also have one blurb in an oddball emergency procedure that correlates engine rpm with VRS:

 

Quote

Reduction of the gas generator rotor speed below 85 to 88 % at a flight speed close to zero even at main rotor speed hold within the acceptable limits, results in helicopter transition to vertical descent at a rate up to 20 m/s (vortex ring condition).

 

Edited April 14, 2021 by AlphaOneSix

[Fri13]

2 hours ago, cw4ogden said:

@Fri13 I want to run a couple tests once DCS finishes updating.  I'm going to try to find the actual source of what feels wrong and see if I can provide an example of it.  

 

Don't take a stress about it, as I trust you that you have good starting point to go for the problem source.

 

Quote

I take your points, and I'd reiterate I'm not saying it's off by a lot.  It needs a tweak.  Not an entire rework.  The coding is good for VRS, I like how they modeled it.  I just question it's accuracy based the fact everyone has to learn how to fly the DCS mi-8.  Everyone qualifies their statement with, I had trouble with VRS at first, but I learned to live deal with it.  

 

I have my own opinions what is missing in the Mi-8MTv2, like some kind a "weight" or "grip" that is difficulty to really point out. It can be about the feeling as well how the VRS feels to behave as well, as for some reason it is as well enjoyable as that there could be something off. 

 

Quote

The actual reality is the vast majority of people never experience VRS.  Not intentionally, nor inadvertently.  VRS accidents are rare.  They happen, but they are rare.

 

Doesn't Mi-8 pilots train for a VRS in a controlled and safe fashion at higher altitudes how it happens and how to recover from it?

At least I think some would have some experience for it, while no one really want to experience it at all at any altitude.

 

Quote

And DCS doesn't feel wrong, necessarily.  Just wrong for the conditions, lightly loaded aircraft operating near sea level, it's far too aggressive.

 

That might be it. I have just the feeling that the mass/inertia is somewhat missing and it can be about that light Mi-8 feels little too easily "going in" without loading it to maximum, and even then it has some odd thing.

 

Quote

  The current flight model is what I would expect to feel operating at high altitude near max gross weight.  Conditions where you are on the edge of the phenomenon.  Not sea level, not lightly loaded and not doing a simple approach to landing.

 

I believe you might have something there. As if I compare Mi-8 to something else like KA-50 that is heavier than a Mi-8, it has this interesting inertia. It has the feeling that air grabs you. That is missing from the Mi-8.

Based to testimonies about KA-50 vs Mi-8 and Mi-24, the KA-50 should be superior at the high altitudes and high cross winds like on mountains. But I don't get that feeling. 

That is why I am interested to see how Mi-24 behaves as it should be more stable and more "direct". 

 

But nothing of that can be trusted than as a opinion and requires more evidence. 

 

Edit: Need to point out that I have been flying SA342 for the last couple weeks as primary helicopter, and its Flight Modeling is destructive. It totally is terrible for your capabilities fly any other helicopter. It takes time to get use to when transitioning from others, but you get to use for its game style flying by how wrong it is. And when you come back to Mi-8, as I have now done to prepare for Mi-24, it makes all senses to say "THIS IS WRONG!" as you just got to completely different experience. 

 

I don't recall such major problems when going between KA-50 and Mi-8 alone. Or Mi-8 and UH-1 as all those behaves more as expected.

Edited April 14, 2021 by Fri13

[Looney]

I'm not going to touch upon the current VRS conditions in the Mi-8 but from a wider point of view, the MI8 is a module integrated into an existing simulation engine. Up to how far this engine is able to recreate atmospheric conditions that will allow a module to fly "right" is something we do not know.

 

We know from certain bits of information that the whole rotor system is calculated by the module itself, there are different approaches to that in each RW module. What we don't know is how this interacts with the simulation engine that's under the hood. 

 

Having seen how far the other modules will go over published flight models and survive as well as the other way around, crash well within the envelope, it may mean the sim engine itself is not up to par to allow a module to fully simulate its rotor system in any atmospheric condition like pressure, temperature, humidity and wind.

 

It may improve, it may not, currently the dev-time is, as always, limited and most likely going into the AH-64 but maybe someday will come that they'll take a look at the MI8's behaviour as well as their own engine and make tweaks/repairs.

[cw4ogden]

I did some testing and am leaning towards a theory:

 

The VRS issue I have may be the autorotative brake state not being implemented, or implemented correctly.  Also called windmill brake state.  

Test number one I repeated a few times, but want to try more iterations was as follows:

 

1000' AGL near zero forward airspeed, rate of descent around 400 m's on the VSI.  

 

Results: modeled well.  Feels right for an out of ground effect, high OGE, "I got distracted" type of VRS.  
Pitch / roll controllability remains good, if not a little too good in a developed Ring state.  
What I was unable to do, and leading back to the first point, was break a developed ring state by dumping collective and entering the windmill brake state.

methodology: High OGE hover, induce VRS, confirm by adding collective, verify increased vertical descent rate - corrective action, bottom collective pitch and break the vortex via upflow through the rotors - does not seem to work as it should.



Test number two:

 

Tactical approach to LZ style landing / traditional dust landing style approach.  (Fast approach, with an aggressive decel - understanding we are talking cargo helicopter standards)

This style approach should also be riding the autorotative brake state, and yet, what it feels like is I still have to avoid VRS criteria during transition through ETL, even though my rotor is mostly unloaded, due to the upflow resulting from the decelerative attitude.  You can't simultaneously have a vortex ring building while the rotor is being driven, or is unloaded by autorotative upflow. 

You can get into a VRS type state by botching the approach and arriving too high, but flown to the ground in the manner of what would be a dust landing, but flown properly, the airflow never comes up through the rotor disk.  

Additionally and possibly related, dumping the collective to the floor in cruise flight, again in the autorotative brake state regime, the aircraft falls out of the sky.  It shouldn't. It feels like upflow and autorotative brake state is not working, or not strong enough.  If I dump the collective with, say 100 knots forward airspeed, I should be able to remain in level flight for quite a while, in a decelerative attitude, exchanging speed for level flight.  The hip just seems to drop like a rock regardless of how much rotor disk you tilt into the wind.

Edited April 15, 2021 by cw4ogden

[cw4ogden]

6 hours ago, Looney said:

I'm not going to touch upon the current VRS conditions in the Mi-8 but from a wider point of view, the MI8 is a module integrated into an existing simulation engine. Up to how far this engine is able to recreate atmospheric conditions that will allow a module to fly "right" is something we do not know.

 

We know from certain bits of information that the whole rotor system is calculated by the module itself, there are different approaches to that in each RW module. What we don't know is how this interacts with the simulation engine that's under the hood. 

 

Having seen how far the other modules will go over published flight models and survive as well as the other way around, crash well within the envelope, it may mean the sim engine itself is not up to par to allow a module to fully simulate its rotor system in any atmospheric condition like pressure, temperature, humidity and wind.

 

It may improve, it may not, currently the dev-time is, as always, limited and most likely going into the AH-64 but maybe someday will come that they'll take a look at the MI8's behaviour as well as their own engine and make tweaks/repairs.

I know it's a long shot getting any re-look.  I'm trying get to the bottom of whether or not it's even a problem, which by community standards, is an un-setttled question.

 

[AlphaOneSix]

27 minutes ago, cw4ogden said:

Additionally and possibly related, dumping the collective to the floor in cruise flight, again in the autorotative brake state regime, the aircraft falls out of the sky.  It shouldn't. It feels like upflow and autorotative brake state is not working, or not strong enough.  If I dump the collective with, say 100 knots forward airspeed, I should be able to remain in level flight for quite a while, in a decelerative attitude, exchanging speed for level flight.  The hip just seems to drop like a rock regardless of how much rotor disk you tilt into the wind.

 

Yeah that seems kind of crazy, since dumping the collective is a sure fire way to immediately over speed the rotor. The flight manual restricts collective movement to no more than 1 degree of blade pitch change per second. Even when practicing autorotations with the engines reduced to idle, you have to be careful how quickly you drop the collective as it will still overspeed the rotor. This aircraft has a very high inertia rotor system, the blades alone weigh 1500 pounds. You should definitely be able to trade airspeed for altitude weigh the collective lowered. I will double check some of these things as I’m flying with a DPE tomorrow. He is used to me asking him oddball questions like this, though. 

[Oubaas]

On 4/14/2021 at 2:17 PM, cw4ogden said:

The actual reality is the vast majority of people never experience VRS.  Not intentionally, nor inadvertently.  VRS accidents are rare.  They happen, but they are rare.

And DCS doesn't feel wrong, necessarily.  Just wrong for the conditions, lightly loaded aircraft operating near sea level, it's far too aggressive.

 

Attempting to communicate the real world reality of VRS around here is an exercise in futility. They've read books and seen YouTube videos. Thousands of hours of real world flight time and experience are no match for books and YouTube videos around here.

 

I invite your attention to any of the DCS helicopter forums. I gaze in wonder at the pages, as people who have never flown a helicopter, and who don't even possess actual helicopter-style controls with which to fly the helicopters in the sim, pontificate on the fine points of rotary aviation and helicopter flight dynamics.

 

As an old retired military fellow myself, with many years of real world aviation experience, I've learned to just laugh and ignore the drivel. And I strictly avoid offering advice or information. If others choose to do so, that's fine. I know when to pay attention and when to roll my eyes and walk away in these discussions.

 

Unfortunately, there are notable cases where the incessantly bellowed, rude, truculent BS offered by the armchair experts has been magically transmogrified by constant repetition into "ultimate truth". When that happens, we all suffer. I can only hope that the developers know when to listen and when to ignore.