Gazelle and VRS

[kintaro]

Well if you mean the sudden rate of descent increase that solves itself then yes, i see VRS.

But unfortunately that is not how it works for VRS. A lot more helicopters would be in one piece around the world if that was true.

I dont want to offend anyone, im just waiting for a good explanation, maybe the gazelle is an exception aerodinamically. Im sorry but this video doesnt give me the explanation. But thanks.

[Holbeach]

You don't see VRS in this video ?

 

Nice video, but, if you can recover from VRS simply with a slight pull on the collective, then you are not in VRS.

 

..

[kintaro]

Im not this mad actually, but agreed with Holbeach.

[Deezle]

Before the VRS was pretty violent, now it doesn't seem to exist at all. Hopefully we can find a good middle ground.

[Fredo_69]

Thank You - Kintaro!

Thank You - Holebeach!

I'm am with You both and hopefully the Gazelle FM will get fixed some day?!

[charlesnett]

i have been considering a gazelle purchase but after reading all of these FM issues and seeing the above vid now i think i will wait. in that vid the gazelle should have gone into VRS and crashed. this is a fundamental characteristic of a helicopters FM and with out this feature the gazelle to me is not a sim of the aircraft yet. i will wait until it is. i have seen poly do some cool things with their module like multi-crew so i am hoping they can fix the FM

[Frusheen]

I'd much prefer to see active testing from the Polychop team on this and other flight model issues rather than videos of fitting hellfires etc...

 

The priority in a full fidelity flight simulator has to be the flight model first.

[Fredo_69]

I'd much prefer to see active testing from the Polychop team on this and other flight model issues rather than videos of fitting hellfires etc...

 

The priority in a full fidelity flight simulator has to be the flight model first.

+1

[Scarecrow84]

I agree that the FM should be the top priority.

 

I have full confidence you guys can get it to the same level as the Huey.

 

For the record, I actually liked some aspects of the original, highly sensitive FM better than the current iteration. I actually use -10% curves on cyclic to make it feel tighter now.

 

I always found it strange how the cyclic re-centers after each input with the gazelle. I barely use trim at all, unlike the Huey. I'm not sure if this is reflective of IRL Gazelle behavior or not, but it's very different than the Huey.

 

I have to agree with the "floaty" and "railly" descriptions. Not that those are actual words, but they get the idea across...

[Mt5_Roie]

I'd much prefer to see active testing from the Polychop team on this and other flight model issues rather than videos of fitting hellfires etc... .

 

Your probably watching the wrong channel yet. My work with the Mod is on my own free time and the videos are on my youtube channel, not polychops. Plenty of official testing goes on during the week, how I spend my weekends is up to me.

[kintaro]

i have been considering a gazelle purchase but after reading all of these FM issues and seeing the above vid now i think i will wait. in that vid the gazelle should have gone into VRS and crashed. this is a fundamental characteristic of a helicopters FM and with out this feature the gazelle to me is not a sim of the aircraft yet. i will wait until it is. i have seen poly do some cool things with their module like multi-crew so i am hoping they can fix the FM

 

That is a very good call. I wish i did more reading before purchase. I think this is the first "advanced" module in DCS that is not up to the level that it should be after release. I know some say its in beta but i would say it's even early to call it that. It ignores most of the physics or aerodynamics involved in helicopter flight. It doesn't have an advanced flight model, and its not even close. So I suggest waiting if you are looking for helicopter simulation. If you are ok with a game like flight model, its should work for you. The 3d model looks nice, the systems work nice its only the AFM thats missing.

I really hope this will not happen again in future modules, i feel like i should have bought something else with that money :(

[The M]

The big problem is the flight model when you turn off the assistance systems. A lot of people think the flight model is wrong and game like because it's diferent than the Huey.

There are Problems, but they are not as big as people say.

[kintaro]

A lot of people think the flight model is wrong and game like because it's diferent than the Huey.

.

 

I am not comparing it to the Huey, im comparing it to flying actual helicopters, and important things are missing, its not just a little bit off.

[The M]

The biggest problem i have with the flight model is the feeling that everything is too "clean" and smooth with the SAS running. And without, it appears the flight model is missing the physikal effects people mentioned.

I get that you are supposed to fly it with the SAS engaged but the SAS feels too perfect.

 

When it comes to VRS i noticed that the Gazelle is fighting the VRS. As soon as i enter it, i start to move and it´s over

[borchi_2b]

Please consider that the SA342M has completely different blades then any other -gazelle ever had. I myself had to learn a few things abut that 342M and thought things are not ok, but in the end, what we received from so many channels of intel, all seems to be close to the SA342M as it should be. Little things here and there need a tweaking yes, but the FM is very close to the real helicopter. By the way, if anybody says it should fly like x or y, it is interesting that nobody ever mentioned tht there is no elicopter in the world that flys like the other of the same kind. They all have thier unique flightbehaviors.

We can only bring it close to what it should be but it will never be the THING of 100% cause it can not be, ever.

[Ramsay]

Please consider that the SA342M has completely different blades then any other -gazelle ever had. I myself had to learn a few things abut that 342M and thought things are not ok, but in the end, what we received from so many channels of intel, all seems to be close to the SA342M as it should be. Little things here and there need a tweaking yes, but the FM is very close to the real helicopter.

Ok, if that's the feedback from RL Gazelle pilots but it does seem strange.

 

I'm used to thinking of a helicopter rotor system having 3 flow states.

 

where does the Gazelle fit in a 'standard' VRS model like that of 'Model for Vortex Ring State Influence on Rotorcraft Flight Dynamics by Wayne Johnson, 2004 (ADA526709.pdf).

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA526709

 

and why does the SA342M self recover from a VRS with no attitude or translation changes, while a AS350 does not?

 

Edit

Note: I'm looking for what breaks 1 of the 3 conditions for 'Settling with Power'

• Descent rate more than 150 m/min (490 ft/min)
  
• Air speed less than ETL < 30 km/h (16 knots)
  
• Power (torque ?) 20 - 100%
  

or why the SA342M is different.

 

R22 VRS ref. image

http://i118.photobucket.com/albums/o95/ichris7/R22%20VRS%20Chart_zpsxdocagiu.jpg

Edited November 28, 2016 by Ramsay

[borchi_2b]

Have you ever encounterred the VRS in the Gazelle ? I have many times and also in high hover conditions in DCS 2.0 and I dropped like a stone and could not recover as usual like at low altitudes in the kaukasus region just pulling the collectiv to a max position, overtroque and keep flying

 

The video looks impressing but rather scry, cause I have no clue why the pilot did pull the collective, he should have nosed down and recovered from the VRS that way. the extrem yaw to the left is an indiction for the collective pull.

I hate to look at videos of accidents and take them into account for a discussion, cause in the end we have zero intel on the conditions.

 

for example, the stealthy black hawk on the operation jeronimo, the pilot who ended in a crash was one o the 2 best army helicopter pilots. What happened, the heat build up in the compound made the engine lose power and the hover was not possible anymore and he ended in a state similar to VRS in combination with a loss of power. today we do know, but back then we only saw the tail and speculations blew the net.

As long there are no hard facts it is a speculation and we do not like them on our end, to be honest.

 

Lately I flew many many hours with a Kiowa pilot and i asked him, what do you think of the gazelle after you have flown her for many hours now. He likes it a lot, cause it reminds him of his real life workhorse.

 

Anyways, we try to keep track on the things that are discovered. some things that are mentioned by users sometimes are bugs, but sometimes they are not. Plus some of the guys of the french army are members in the forum too and read careful what people write about thier helicopter in the sim.

Thanks to these guys, although I will not reveal thier names

Edited November 29, 2016 by borchi_2b

[Fredo_69]

That is a very good call. I wish i did more reading before purchase. I think this is the first "advanced" module in DCS that is not up to the level that it should be after release. I know some say its in beta but i would say it's even early to call it that. It ignores most of the physics or aerodynamics involved in helicopter flight. It doesn't have an advanced flight model, and its not even close. So I suggest waiting if you are looking for helicopter simulation. If you are ok with a game like flight model, its should work for you. The 3d model looks nice, the systems work nice its only the AFM thats missing.

I really hope this will not happen again in future modules, i feel like i should have bought something else with that money :(

+1

[fjacobsen]

I know this is the Gazelle forum, but still...

 

For some years ago I got the chance to try a UH-1D simulator at the German army's simulator center at Bückeburg - cool experience.

 

I aksed the instructor about VRS in a UH-1D and he told me that it was almost impossible to get into VRS in a normally loaded UH-1D by accident.

You can force into it if You really want, but otherwise it would not enter it easily.

 

I think many heli-sims exaggerate VRS making it too easy to enter, thats also what I experience with the Belsim Huey and thats why some want to see the Gazelle go into VRS easier too.

 

Personally I have entered into VRS in the Gazelle quite a few times, so it is modelled.

[zaelu]

I don't think people want it to get easier.

 

Simply to recover by proper procedures, aka exit the vortex laterally or longitudinally and not simply apply collective (which should work exactly in the wrong way).

Maybe BST UH1H enters too quickly although rarely I flew it "soft loaded"... mostly heavy... but the way the helicopter acts when enters VRS is scary. It twists and shakes like a beast in a snake grip. I get the same experience with Gazelle only when I take off if I touch the cyclic... which is...

[Johnny Dioxin]

I wouldn't worry too much, regardless of what you do, someone will be complaining and telling you how it should be. :thumbup:

[Ramsay]

I aksed the instructor about VRS in a UH-1D and he told me that it was almost impossible to get into VRS in a normally loaded UH-1D by accident.

You can force into it if You really want, but otherwise it would not enter it easily.

My understanding is that VRS is usually in an unstable region of flight dynamics and a helicopter will naturally pitch or roll inducing a translation that increases it's air speed above ETL and effectively fly out of VRS, having lost some height.

 

However if a pilot or SAS holds a stable attitude while the air speed decreases and decent rate increases beyond safe limits, a VRS can be induced either intentionally during training/tests or unintentionally when landing, etc.

 

Although some air frames have predictable VRS characteristics, as VRS are an unstable region, others do not.

 

Taghizad (2002) - SA 365N Dauphin 6075, tested at the French Flight Test Center (CEV).

Taghizad, et al. concluded that flight in vortex ring state was unpredictable. Two VRS flights starting from close conditions could imply very different helicopter reactions.

This chaotic behaviour is probably explained by the turbulent flow producing VRS. For the majority of tests, a collective increase alone did not permit the helicopter to leave the VRS

regime.

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA526709

 

I think many heli-sims exaggerate VRS making it too easy to enter, thats also what I experience with the Belsim Huey and thats why some want to see the Gazelle go into VRS easier too.

When the Belsimtek Huey enters VRS, I find it will naturally pitch down, inducing forward translational motion (above ETL) and fly out of a VRS. Only by deliberately (or instinctively) holding a level attitude, while allowing forward air speed to fall and the decent rate to increase, could I hold and maintain a VRS.

 

While I can't know if a Huey's VRS is modelled correctly, I do feel I understand why Belsimtek's Huey does, what it does.

 

Personally I have entered into VRS in the Gazelle quite a few times, so it is modelled.

And how did you get out of it? Did you try just increasing collective or use techniques learn't flying the Huey?

 

I got lots of practice in the Huey while waiting for the Gazelle to come to 'Steam'. When it did, I didn't really notice the issue with VRS as I was flying with habits learn't from the Huey. It was only after I saw reports from posters who I consider 'reliable', that went out of my way to check VRS because I 'knew' it was there, it wasn't, a fistful of collective can save me from VRS every time.

 

This isn't a thread to bash the dev's or ask the Gazelle to enter VRS easier (490 ft/min, 16 knot fits well on the R22 plot). It's to report a possible bug and/or seek an explanation for it's behaviour.

[Aginor]

I also have entered VRS a few times in the Gazelle (The DCS Gazelle that is). I usually managed to leave it by moving out of the vertex laterally.

Edited November 30, 2016 by Aginor

[Fredo_69]

I wouldn't worry too much, regardless of what you do, someone will be complaining and telling you how it should be. :thumbup:

I've stopped flying the Gazelle because it's FM is so unfinished and I just get annoyed... I won't touch it again before I read in this forums that it's received some major FM update!

[Frusheen]

I wouldn't worry too much, regardless of what you do, someone will be complaining and telling you how it should be. :thumbup:

 

People are trying to offer constructive feedback not complain. They have even gone as far as posting links on a very technical issue to illustrate the problem. VRS is modeled just not correctly. I'm another one who has stopped using the gazelle until it's flight model is improved to obey the laws of physics. See my other thread regarding lateral tail rotor thrust and cyclic stability for example. I'm currently filled with hope and dread for the bo105. I want the Polychop helicopters to be the best in DCS. In spite of the fantastic rendering and good systems modeling in my opinion the Gazelle is currently the worst helicopter in DCS due to the poor flight model. If I want to just look at well rendered helicopters that don't fly right I'd install P3d or FSX.