Баги, проблемы Великолепной Восьмерки

[Wadim]

2 часа назад, sLYFa сказал:

Пожалуйста, читайте внимательнее мой пост. Я НЕ спрашивал, что такое ВК и как с ним бороться и обсуждать тоже ничего не собираюсь. Речь идёт о не соответствие модели с реальными данными по области режима ВК. Причём не в рамках какой то малой погрешности, а поведение модели противоположное тому, что пишется в практической аэродинамики по Ми-8. Для наглядности ещё диаграмма. Так ВОТ вопрос: Это баг или всё таки такое поведение правильно (вопреки реальной литературе)? 

 

Это, уважаемый, чушь какая то на вашей диаграмме. Чем больше поступательная скорость, тем больше вертикальная скорость?
Где такое видано?
Откуда вы "это" взяли.
Может быть я чего то не допонимаю...

[sLYFa]

8 minutes ago, Wadim said:

Чем больше поступательная скорость, тем больше вертикальная скорость?
 

Так как раз в этом и проблема, так быт не должно, а в ДКС именно такое наблюдается. А "это" результат испытании в ДКС. Смотрите треки, которые я выше выложил или пробуйте сами, на какой вертикальной скорости вы попадёте в ВК на скорости 30км/ч. 

Edited May 31, 2021 by sLYFa

[Frogen]

1 час назад, sLYFa сказал:

Так как раз в этом и проблема, так быт не должно, а в ДКС именно такое наблюдается. А "это" результат испытании в ДКС. Смотрите треки, которые я выше выложил или пробуйте сами, на какой вертикальной скорости вы попадёте в ВК на скорости 30км/ч. 

 

МДА... в том то и проблема, что местным диванным экспертам сложно объяснить простые вещи... 

Итак Есть ОПЫТ. Для того, что бы опыт в итоге дал ПРАВИЛЬНЫ результат, необходимо:

1. Теоретическое обоснование явления.

2. Использование правильных методик проведения опыта или эксперимента

3. Использование правильных измерительных приборов или инструментов.

4. Умение систематизировать и оценить полученные материалы.

5. Сделать вывод,

 

Начнем с теории , и на ней и остановимся, её будет достаточно.. 

По принятой в СССР и РФ теории, которая озвучена в книгах по аэродинамике вертолета , как правило под редакцией В.Ф.Ромасевич (в соавторстве с различными авторами) скорость полёта вертолёта,  для определения величины вертикальной скорости снижения,  в режиме вихревого кольца не учитывается.

Выдержка ниже. Краткий формат форума и этой темы , не позволяет более обширно довести данный материал. Настоятельно рекомендую начать изучение материала по ссылки на документы Сызранского ВВАУЛ, и далее самостоятельно. 

 

Т.о. то, что вы озвучили, интересно, но при этом, для понимания,  требует ознакомления с теоретическими трудами , положенными в основу исследования, которое Вы привели выше, и далее по пунктам, изложенным выше в этом топике .

С уважением..  

 

Edited May 31, 2021 by Frogen

[cw4ogden]

2 hours ago, Wadim said:

This, dear, is some kind of nonsense on your diagram. The higher the forward speed, the higher the vertical speed?
Where have you seen this?
Where did you get "it".
Maybe I don't understand something ...

He observed the data. It's from his own flight testing it, and he and I want others to test our findings. That is all.  
 

Why does everyone just jump to the conclusion: “He must not know what he's talking about”? And how can you arrive at any conclusion when it's clear from your questions, you don't even know what he is saying?

 

Sorry for the English, but this comes from my thread in the English forums.  

Edited May 31, 2021 by cw4ogden

[sLYFa]

50 minutes ago, Frogen said:

МДА... в том то и проблема, что местным диванным экспертам сложно объяснить простые вещи... 

Итак Есть ОПЫТ. Для того, что бы опыт в итоге дал ПРАВИЛЬНЫ результат, необходимо:

1. Теоретическое обоснование явления.

2. Использование правильных методик проведения опыта или эксперимента

3. Использование правильных измерительных приборов или инструментов.

4. Умение систематизировать и оценить полученные материалы.

5. Сделать вывод,

 

Начнем с теории , и на ней и остановимся, её будет достаточно.. 

По принятой в СССР и РФ теории, которая озвучена в книгах по аэродинамике вертолета , как правило под редакцией В.Ф.Ромасевич (в соавторстве с различными авторами) скорость полёта вертолёта,  для определения величины вертикальной скорости снижения,  в режиме вихревого кольца не учитывается.

Выдержка ниже. Краткий формат форума и этой темы , не позволяет более обширно довести данный материал. Настоятельно рекомендую начать изучение материала по ссылки на документы Сызранского ВВАУЛ, и далее самостоятельно. 

 

Т.о. то, что вы озвучили, интересно, но при этом, для понимания,  требует ознакомления с теоретическими трудами , положенными в основу исследования, которое Вы привели выше, и далее по пунктам, изложенным выше в этом топике .

С уважением..  

 

 

К чему это всё? Я вам представляю (довольно простые) сравнительные данные, а вы опят раскатываете теорию про ВР, причём не слово а том, чем обосновывается границы области режима ВК (что в этом случае было бы в помощь). Так вот дайте мне вам представить "диванную экспертизу": "[... ] область режимов полета с характерными явлениями «вихревого кольца» определяется сочетанием поступательной и вертикальной скоростей или, что то же, углом снижения вертолета" - это цитат из учебника по практической аэродинамики Ми-8МТ. Кривая "реал" в диаграмме представленой мною, тоже от туда. И именно такие же границы области режима ВК должен иметь вертолёт в ДКС, что, как проявили испытания, он не имеет. Не верите, смотрите треки. 

По методикие испытании:

-Штиль, 15°С, 760мм на аэродроме. 

-поступательная скорость отчитываться по ДИСС, вертикальная по вариометру. Оба прибора в ДКС практически не имеют погрешности из-за чего довольно точно можно мерит выше указанные параметры. 

Очень вас прошу, если вас эта тема интересует, прочитайте внимательно мой посты, просмотрите треки и если тогда будут КОНКРЕТНЫЕ претензии к выполнению испытании или источников, отпишитесь. А пускать флуд считая, что я не умею летать, не знаю аэродинамику и не умею/не хочу осваивать литературу, не стоит. 

[cw4ogden]

28 minutes ago, sLYFa said:

the flight speed of the helicopter is not taken into account in the vortex ring mode to determine the value of the vertical descent rate .

This does not seem to make sense. By this logic I can get into Vortex Ring State in cruise flight, if I descend at a fast enough rate.  
 

Vortex Ring state only happens below ETL. The definition of ETL is you have left your downwash   
 

No VRS possible above ETL.

 

Below ETL, the downwash can be reinvested by the rotors, yes.  
 

but the rate of descent required should scale progressively from taking a very high rate of descent near ETL to a lower rate of descent to produce the onset of VRS, at 0 airsieed.

DCS does not do this, The most dangerous area for VRS, appears to be right around ETL, and gets more forgiving as you slow down more.   At the ETL transition point, the phenomenon is acting mostly on the back side of the rotor, the induced flow from the front of the disk being ingested in the rear.  
 

if you get into VRS transitioning through ETL, as opposed to from an OGE hover, The onset is a very progressive phenomenon. It starts at the back of the rotor system and works its way forward as you slow down.
 

The front half of the rotor will still have clean air near ETL, as will most of the back half.

 

And according to every VRS diagram I've ever seen, an approach angle of less than thirty degrees keeps you clear of the VRS hazard area, regardless of your rate of descent. Also not modeled on DCS mi-8.
 

Feel free to test this out, But provided the Gentleman's DATA and mine checks out, The flight model is bugged.

 

 

 

Edited May 31, 2021 by cw4ogden

[cw4ogden]

 

 

It doesn't make sense. By this logic, I can get into a vortex ring state in cruise flight if I descend at a high enough speed. Vortex Ring state only occurs below ETL. The definition of ETL is that you have left your downwash. Impossible VRS above ETL. Below ETL, flushing down can be reinvested in rotors, yes. but the required descent rate must gradually increase from a very high descent rate near ETL to a lower descent rate to a cautious start at zero air ambush. The DCS does not. The most dangerous area for VRS seems to be right in the ETL. At this moment, in flight, the acts mainly on the rear side of the rotor, the induced flux from the front of the disc enters the rear.If you get into VRS by going through ETL and not from OGE hover, the beginning is a very progressive phenomenon. It starts at the rear of the rotor system and moves forward as it decelerates. The front half of the rotor will still have clean air around the ETL, as will most of the rear. And according to every VRS chart I've ever seen, an approach angle of less than thirty degrees keeps you out of the VRS danger zone, regardless of your rate of descent. Also not modeled on the DCS Mi-8.
 

Feel free to check it out, but provided the Gentleman's DATA and mine are confirmed, the flight model contains errors.

 

Edited May 31, 2021 by cw4ogden

[Wadim]

11 минут назад, cw4ogden сказал:

This does not seem to make sense... 

 

It makes no sense to translate.
Who needs it, they understand you.

Edited May 31, 2021 by Wadim

[Frion1]

Сейчас попробовал первую миссию кампании Экипаж - не включается автопилот по каналу крена/тангаж (холодный запуск)

[SL PAK]

27 минут назад, Frion1 сказал:

Сейчас попробовал первую миссию кампании Экипаж - не включается автопилот по каналу крена/тангаж (холодный запуск)

Сами запуск выполняли? Кнопка может не загораться если не обеспечено должное элктропитание. Или там виртуальный экипаж помогает с запуском? Тогда проверяйте генераторы и преобразователи.

[Frogen]

Начнем с того, что пилоты западной школы, не имеют классического высшего образования (по данному профилю) как в СССР и РФ (по поводу РФ, уровень конечно снизился, по известным причинам). У них, там уровень образования от ПТУ до ТЕХНИКУМА. Те, что имеют высшее образование (очень редко профильное, т.е. именно по профессии летчика) , получали его как дополнительное. 

Как базис. Имею высшее профильное образование (во времена СССР кто хотел, тот мог получить отличное образование, просто педантично изучая предметы по программе).

 

У вас системная ошибка в теории.. Границы опасной зоны действительно определяются поступательной и вертикальной скоростью. Но, вертикальные скорости в самом "вихревом кольце", это производные от величины общего шага (а значит от угла атаки элемента лопасти в данный момент времени и мощности двигателей (располагаемой и потребной).

На этом мои пояснения по теме "вихревого кольца" заканчиваются.  Читайте профильную литературу.

 

Что качается практики летной работы. 

 16 лет на летной работе, из низ 5 лет инструктор первоначального обучения на Ми2, и 9 лет инструктором на Ми8. 

Так что, МОИ личные теоретические знания и опыт практической работы летчика - инструктора позволяет мне иметь собственное мнение и бредовыми обсуждениями тут не заниматься. 

И к слову..

будучи курсантом 1 курса, имел ЛИЧНЫЙ, печальный опыт попадания (практически падения с высоты 1200 м до 300м )  на Ми2  в режим "вихревого кольца" . Вошел в историю, т.с. )). Причина - Грубая ошибка техники пилотирования в зоне, на манёвре. И 4 года обучения в ВВАУЛ, преподаватели имели "удовольствие помучить" меня по этому вопросу, в виде дополнительного вопроса на любом экзамене и зачёте по аэродинамике.

Edited May 31, 2021 by Frogen

[cw4ogden]

7 minutes ago, Frogen said:

To begin with, the pilots of the Western school do not have a classical higher education (in this profile) as in the USSR and the Russian Federation (regarding the Russian Federation, the level of course has decreased, for obvious reasons). They have a level of education from vocational school to technical college. Those who have higher education (very rarely specialized, that is, precisely by the profession of a pilot), received it as an additional one. 

As a basis. I have a higher profile education (in the days of the USSR, anyone who wanted to could get an excellent education simply by pedantically studying the subjects according to the program).

 

You have a system error in theory .. The boundaries of the danger zone are really determined by the forward and vertical speed. But, the vertical velocities in the "vortex ring" itself are derivatives of the total step size (which means from the angle of attack of the blade element at a given time and the power of the engines (available and required).

This concludes my explanations on the "vortex ring" topic. Read specialized literature.

 

That shakes the practice of flight work. 

 16 years in flight, from the bottom 5 years as an instructor of initial training on the Mi2, and 9 years as an instructor on the Mi8. 

So, MY personal theoretical knowledge and practical experience of a pilot-instructor allows me to have my own opinion and not engage in delusional discussions here. 

And by the way ..

being a 1st year cadet, he had a PERSONAL, sad experience of hitting (practically falling from a height of 1200 m to 300 m) on the Mi2 into the "vortex ring" mode. Went down in history, t.s. )). Reason - Gross error of piloting technique in the zone, on the maneuver. And 4 years of study at VVAUL, the teachers had the "pleasure to torment" me on this issue, in the form of an additional question on any exam and test in aerodynamics.

 

I submit your experience is sufficient to speak on the subject.  But I don’t understand your conclusion.

 

Are you dismissing the possibility the flight model could be in error, as not a possibility?  
 

it could be the translation, but I didn’t get your intent.  
 

All of That said. Thus far all it seems you are arguing only that you have very good credentials, which I do not deny.

 

So I’m asking maybe to summarize what you meant.  
 

I don’t see how you can dismiss data without evaluating it, based solely on the certificates hanging on your wall.

 

I do not mean to sound satirical, but I accept your qualifications, what do you make of his data?

[cw4ogden]

My qualifications are 20 years US Army helicopter carrier flying CH-47. Not the same, but similar in weight.

 

My source is feedback from a friend who flies both birds and tells me the hip mi-8 does not encounter VRS to any greater extent than the ch-47.

 

I also have first hand experience with VRS that I was not prepared for, so it became very personal to me as a pilot, instructor pilot, and standardization instructor (Instructors who teach and evaluate the junior instructor pilots).

 

but I submit, any actual mi-8 experience you have is a much better yardstick, a better measurement of accuracy.
 

I also submit, circumstantially, the aircraft cannot fly the way it does in real life, the way it does in DCS. 
 

The most dangerous part of the VRS envelope cannot be at the ETL transition airspeed, because you are only half in it at best.  
 

ETL by definition is no vortices.

 

My experience with VRS is it is confined to nearly vertical approaches, (one of the key four factors required for VRS).

 

if you don't have vertical or near vertical descent - No VRS.  
 

Tailwind complicates this, but you must be descending in your own rotorwash for VRS.

 

And I can't descend into what's behind me.

 

You need vertical or near vertical descent. Either as a result of going nearly straight down or coming into land with a tailwind. You must be descending into your own air.

 

But also VRS gets inattentive pilots flying Hover OGE not observing rates of descent,

and also happens on rapid decelerations where you essentially tilt your disk into your upflow. Which puts you in the windmill brake / autoratative region of the graph. This is fine until you try to stop using power and essentially come upwards through the VRS graph. From bottom up into VRS.

 

Usual result is a very hard landing. Sometimes damage to landing gear / airframe. 

Edited May 31, 2021 by cw4ogden

[cw4ogden]

As far as the education goes.  Yes, U.S. pilots are vocational technically trained.  The average U.S. line pilot in command is a very poor study of aerodynamics.  
 

The knowledge scales up as you go up the ladder of responsibility, and many also take it up (aerodynamic engineering) pursuing their bachelor degree.  
 

Ive also known a lot of very book smart people who couldn’t find their way out of a wet paper bag.  And I don’t just mean stupid in general, I mean profoundly stupid in the field they’re supposed to be the expert on.

[sLYFa]

3 hours ago, Frogen said:

 вертикальные скорости в самом "вихревом кольце", 

 

Об этом тут речь никогда не шла. Ладно, заканчиваю "борьбу с мельницой" 

[Wadim]

11 часов назад, cw4ogden сказал:

...

Are you dismissing the possibility the flight model could be in error, as not a possibility?  
...

Although the question is not for me, I will try to answer.

 

I took part in testing the Mi-8 model.
The testing was done very well.
All the facts that were available were taken into account.
We used descriptions of the helicopter's behavior in this mode, including scientific literature. This mode was simulated on a professional simulator on which I work as an instructor. I participate in two research projects on critical flight modes: on the L-39 aircraft (I also mastered this type of IRL) and on the Mi-8 helicopter. In addition, I personally interviewed several test pilots who performed this mode in real life.

 

Considering all of the above, I assure you, the behavior of our model, in this flight mode, has about 99% correspondence to a real helicopter.

[yakutmi8]

13 часов назад, Frion1 сказал:

Сейчас попробовал первую миссию кампании Экипаж - не включается автопилот по каналу крена/тангаж (холодный запуск)

Такое обычно бывает, если не включен ПРАВЫЙ авиагоризонт после запуска движков и выполнения всех положенных процедур перед выруливанием/взлётом.

[cw4ogden]

4 hours ago, Wadim said:

Considering all of the above, I assure you, the behavior of our model, in this flight mode, has about 99% correspondence to a real helicopter.

I don't doubt the sincerity of the effort put into the coding.  I do question the model itself.  Not because you or the team didn't do a good job doing research or gathering data, but because introducing a bug, unintentionally, just isn't as impossible as you want it to seem.  

#1. I understand you believe it is modelled correctly, and it may very well be.  I'm not here to badmouth the development team, but, you've yet to address or acknowledge the discrepancy we found.  It's a discrepancy, something to look into.  I'm not claiming it is hard and fast proof of a bug.  Just asking others to check a quirk that may or may not be responsible for what feels off in the flight model.    

#2. You'd be better served proving to me the Mi-8 flies like the model does in DCS.  In other words, I believe it is within realm of possibilities that the Mi-8 is somehow more susceptible the VRS than other helicopters, but I've seen no evidence of it.  

 

My hypothesis is if the Mi-8 were as deadly in regards to VRS as it is modeled in DCS, there would be much more information in the way of charts and performance planning information.  You'd need it just to survive.  If the real life Mi-8 rides a lot closer to the VRS envelope than my point of reference, in reality, that's acceptable.  I want "correct" behavior.  I don't want a dumbed down version.  I just want it to be accurate.  You believe it is; I am not totally convinced.  Mainly because I can get into VRS in DCS in situations I don't feel I would in real life.  

That may be differences in the aerodynamics of the different aircraft, or it is a bug.  To me it feels like a bug, because I can get VRS in DCS in conditions I assert you couldn't in real life.

I'll add that the modelling of VRS when induced from an OGE hover feels exactly right.  What feels off is being able to get into VRS in situations where the downwash would be well behind the aircraft. 

I can test the data all day long, but I am not an unbiased observer anymore.  I believe, maybe not with 99% certainty, but believe there is a decent possibility an error crept into the flight model.  So I'm asking others who are not vested in the outcome to test what we found.  That's all.  

I am fine with being proven wrong, I'm not an Mi-8 expert.  But if it was my code, my work, I'd want to look into any suggestions I got it wrong.  If it was my community to manage, I'd never let that community flop around like a dying fish for years without putting this to bed.  It's either based in reality, and I'll take the egg on my face, OR, something is slightly off, in which case a fix would be warranted.  I hope you get where I am coming from.  Maybe I am beating on a dead horse, but lets make sure the horse is really dead.

I don't think the modelling is off by much, I think it needs a tweak, not a complete rework.  

[cw4ogden]

@Wadim

Forgive my drawing technique, but this is what I feel is going on.  A VRS susceptibility range that is exaggerated.  

Track file shows aircraft entering VRS from above ETL (which is impossible) at 30 KIAS or about 55 kmph.  Aircraft should not be susceptible to VRS, regardless of rate of descent, or approach angle at that speed, as stated earlier.  Even the Mi8 flight manual says only below 40 kmph.  

 

ETL being defined as operating in clean air.  Above ETL, induced flow is behind the aircraft before it can be re-ingested into the rotor system.  Being above ETL and getting into VRS should be mutually exclusive.  You can't experience both simultaneously; being below ETL is a prerequisite, a requirement for VRS.  

Or, possibly the problem isn't with VRS at all, but the transition airspeed range for ETL, but something seems off if I can get into VRS at 55 kmph, above ETL in conditions the phenomenon can not exist, due to it's very nature.  VRS is re-ingested downwash, and by definition, ETL is when you are free of operating in your downwash.

2.trk

Edited June 1, 2021 by cw4ogden

[cw4ogden]

I've heard a lot of people say essentially, "You're case is purely circumstantial!"  

And I will concede this point, with the caveat: it's a special kind of circumstantial.  
It's a Prima Facie case - Prima Facie -  "sufficient to establish a fact or raise a presumption unless disproved or rebutted."

In my track file, the aircraft enters VRS at 30 KIAS or about 55 kmph.  This is above ETL and above ETL by the very definition of what ETL means, you physically cannot induce VRS, period.  It's an aerodynamic impossibility.

That is not circumstantial, that is prima facie.  

I don't need to prove the MI-8 VRS modelling is wrong, you need to prove to me that the MI-8 can in fact, encounter VRS at 55 kmph.  
On it's face, prima facie - everything we know about VRS says you must be below the effective transitional lift airspeed to encounter VRS.  VRS is a phenomenon of re-ingesting the air you have induced a downward momentum. 

 

"Effective translational lift (commonly referred to as ETL) is a term used to describe the airspeed at which the entire rotor system realizes the benefit of the horizontal air flow. This happens when the helicopter's rotor disc moves completely out of its own downwash and into undisturbed air."

"A vortex ring state is when the helicopter’s downwash recirculates into the induced flow and the helicopter descends while under power."

 

The two are mutually exclusive. I don't have to prove that.  It is correct on the face of it.  My case is prima facie, a very special kind of circumstantial.  I don't have to prove this point, it must be disproven, or the findings to be shown in error.

Edited June 1, 2021 by cw4ogden

[Wadim]

1 час назад, cw4ogden сказал:

@Wadim

Forgive my drawing technique, but this is what I feel is going on.  A VRS susceptibility range that is exaggerated.  

Track file shows aircraft entering VRS from above ETL (which is impossible) at 30 KIAS or about 55 kmph.  Aircraft should not be susceptible to VRS, regardless of rate of descent, or approach angle at that speed, as stated earlier.  Even the Mi8 flight manual says only below 40 kmph.  

 

ETL being defined as operating in clean air.  Above ETL, induced flow is behind the aircraft before it can be re-ingested into the rotor system.  Being above ETL and getting into VRS should be mutually exclusive.  You can't experience both simultaneously; being below ETL is a prerequisite, a requirement for VRS.  

Or, possibly the problem isn't with VRS at all, but the transition airspeed range for ETL, but something seems off if I can get into VRS at 55 kmph, above ETL in conditions the phenomenon can not exist, due to it's very nature.  VRS is re-ingested downwash, and by definition, ETL is when you are free of operating in your downwash.

2.trk 224 \u041a\u0431 · 0 скачиваний

 

 

21 минуту назад, cw4ogden сказал:

I've heard a lot of people say essentially, "You're case is purely circumstantial!"  

And I will concede this point, with the caveat: it's a special kind of circumstantial.  
It's a Prima Facie case - Prima Facie -  "sufficient to establish a fact or raise a presumption unless disproved or rebutted."

In my track file, the aircraft enters VRS at 30 KIAS or about 55 kmph.  This is above ETL and above ETL by the very definition of what ETL means, you physically cannot induce VRS above ETL.  Period.  

That is not circumstantial, that is prima facie.  

I don't need to prove the MI-8 VRS modelling is wrong, you need to prove to me that the MI-8 can in fact, encounter VRS at 55 kmph.  Not the other way around.  

On it's face, prima facie - everything we know about VRS says you must be below the effective transitional lift airspeed to encounter VRS.  VRS is a phenomenon of re-ingesting the air you have induced a downward momentum. 

 

"Effective translational lift (commonly referred to as ETL) is a term used to describe the airspeed at which the entire rotor system realizes the benefit of the horizontal air flow. This happens when the helicopter's rotor disc moves completely out of its own downwash and into undisturbed air."

"A vortex ring state is when the helicopter’s downwash recirculates into the induced flow and the helicopter descends while under power."

 

The two are mutually exclusive. I don't have to prove that.  It is correct on the face of it.  My case is prima facie, a very special kind of circumstantial.  I don't have to prove this point, it must be disproven, or the findings to be shown in error.

I don’t understand why you are saying all this?
Do you think the model will be changed?

What's the point of your messages?

[cw4ogden]

8 minutes ago, Wadim said:

 

I don’t understand why you are saying all this?
Do you think the model will be changed?

What's the point of your messages?

To identify if there is a bug.  
Yes!, Of course, I think the model should be changed, if it is found to be incorrect.  Who wouldn't?

I don't understand why you can't look at the data?  
Or explain how a helicopter encounters VRS above ETL?

You make an assertion everything is correct, but offer only reassurances and credentials without addressing the points made.

My point is to find out if the flight model is accurate.  You say yes.  And you should know, but also can't answer my very simple questions, like how does a helicopter get into VRS above ETL.  This should not be possible, do we agree on that?

Edited June 1, 2021 by cw4ogden

[Wadim]

26 минут назад, cw4ogden сказал:

To identify if there is a bug.  
Yes!, Of course, I think the model should be changed, if it is found to be incorrect.  Who wouldn't?

I don't understand why you can't look at the data?  
Or explain how a helicopter encounters VRS above ETL?

You make an assertion everything is correct, but offer only reassurances and credentials without addressing the points made.

My point is to find out if the flight model is accurate.  You say yes.  And you should know, but also can't answer my very simple questions, like how does a helicopter get into VRS above ETL.  This should not be possible, do we agree on that?

 

 

[cw4ogden]

10 minutes ago, Wadim said:

 

I've watched that video and the other VRS Mi-8 accident several times and I have two takeaways / observations:

 

Number one:  He has no forward momentum at all.  None.  That is to be expected when you descend straight down like he tried to.

Number two:  That pilot applied no corrective action.  He pulled more collective.  

That tells me he didn't know what was wrong with his aircraft.  He crashed from lack of training.  He failed to identify the emergency proceedure and was therefore unable to apply corrective action. 

Which also tells me VRS accidents in the MI-8 are rare.  Or there would be a strict training proceedures, proliferous amounts of literature, and way more accidents, none of which seems to exist.  The Mi-8 is one of the most fielded helicopters in history, and you can find exactly two videos of VRS accidents and they are both pilot's going straight the hell down.  Not moving, not above ETL.

Those pilots crashed in vertical descent profiles, and they by all appearance, where caught completely off guard by VRS.  That is not the same as the bird being overly dangerous.  They were overly careless.  Or they did not fully understand the flight profile they were operating in.

And you still can't answer a simple question of mine.  How does a helicopter encounter VRS above ETL.  Have you watched the track files.  Have you tested any of this yourself, or are you just trolling me at this point?

Let's just start there and see if we can agree on one simple thing as fact.  Can you get into VRS above ETL.  It is a simple place to start.  Yes or no?

Edited June 1, 2021 by cw4ogden

[cw4ogden]

What you are arguing is that because we have one video of a VRS accident, the aircraft is "dangerous" and therefore the flight model is correct.  That's some pretty specious reasoning.
That video, that accident is not representative of anything I've asserted.  I've have stated, induced from an OGE hover, the modeling is great.  It reacts just like the video and is everything I would expect from a VRS simulation.

But find me a video with an Mi-8 doing 55 kmph and crashing from VRS.  That would be useful evidence.  This is not.  The aircraft should do exactly what it did in that video and it does in DCS.  It just also does a whole lot more, like kill you from VRS above ETL which is a fugazi.  It's a phony.