DCS Huey and VRS

i just got into VRS at 2000 ft

entered at about -1000 fpm

increased collective to max egt and torque of about 46

and it increased to -3400fpm.

i kept on the collective till ground effect. went straight through it and exploded.

so it works on mine.

i

Taking Gunnars_Driver's risk formula and say applying it to an R22, agrees with the VRS chart for that helicopter (note I don't recall the chart's original source).

 

Vih = Theoreticall downwash = Square root of ( T / ( 2 x p x A) )

Aircraft       = R22						
Weight (w)     = 1370lbs       = 623 kg
Thrust (T=wg)  = 6109 N
Rotor Diameter = 25.2 ft       = 7.7 m
Rotor Area A   = 46.332 m^2
Downwash Vih   = 7.336 m/s     = 1445 ft/min	
0.5 * Vih      = 3.7 m/s       = 723 ft/min

Yes, and if you look at the safe levels in my other post(as per your link earlier), the safe level is set to 0.3 x Vih. 0.4 is amber meaning that you are closing in to the downwash and safety is slightly reduced. 0.3 x Vih for that R22 = 500fpm.

The VSI (vertical speed indicator) has some lag due to how it need to be built, and to be sure not getting above 500fpm due to the lag, the common sense tought at flying schools to students flying smaller lighter helos is 300fpm. Thats the reason you can read 300fpm in a lot of places.

However, this doesnt mean that you will get into VRS at 301fpm.

High risk of entering VRS will be reaching 0.6Vih or above, thats 900fpm, for that R22.

i just got into VRS at 2000 ft

entered at about -1000 fpm

increased collective to max egt and torque of about 46

and it increased to -3400fpm.

 

i kept on the collective till ground effect. went straight through it and exploded.

 

so it works on mine.

If you add on that much power yes. What I'm pointing to is that VRS begins slowly and increases if you don't get out the down wash IRL; in DCS Huey you can stay in the down wash and it won't increase unless you add on a lot of power.

IRL you wouldn't have to add on more power, because as the helicopter falls into it's own down wash it picks up speed so the down wash increases to, which will make the helicopter fall faster and the down wash increases so on and so forth. Adding on more power will accelerate the descent rate, but it's not necessary to increase the descent rate.

VRS is easy to get out of if you have enough altitude and you know how, the reason pilots crash from VRS is they're too low or they in a confined area, or they simply panic and try to increase power to get back lift.

Yeah, VRS is simulated in DCS Huey, it's just not completely realistic.

Next topic LTE.

Yes, and if you look at the safe levels in my other post(as per your link earlier), the safe level is set to 0.3 x Vih.

Are you telling me I can set the safe level in DCS Huey? That was my original question "I'm wondering if this is a bug that's came with the latest update, also wonder if there's a setting in a config file somewhere that I can tweak to make the physics more realistic"?

Are you telling me I can set the safe level in DCS Huey? That was my original question "I'm wondering if this is a bug that's came with the latest update, also wonder if there's a setting in a config file somewhere that I can tweak to make the physics more realistic"?

I’m telling you the real life facts of VRS.

Vih is a way of describing the speed of the downwash with a calulation based on weight, rotor diameter and the density of the air.

If you are descending with the value of Vih and also a lot of power, you’re in high risk of getting into VRS.

If you look at the post Ramsay linked to you have a table with colored values of different descent rates, also described on terms of shares of Vih( 0.X times Vih).

Green is safe, red is dangerous and the progressive colors between is increasing risk of getting VRS. Stay in green and houre safe.

There is three parts needed to getting into VRS in a descent:

- Descent rate high enough(as per the formula)

- Power high enough( 20% is not enough)

- Descent angle is more or less exactly vertical in still air and if not still air, angled so you fly with thame directionnand speed of the wind.

Take away one of the facts and you won’t enter VRS.

IRL last point is the hardest: if trying to get into VRS it can be hard to follow the wind absolutely perfect and thereby not developing VRS.

The reason it is so dangerous is that it wont come each time because it hard to actually stay with the exakt speed of air. Pilot can do ”dangerous landings” a lot of times feeling safe and the next time develop VRS.

I’m telling you the real life facts of VRS.

Pilot can do ”dangerous landings” a lot of times feeling safe and the next time develop VRS.

That's why we taxi, take off, land and taxi into the wind, always.

So, what you're saying is I can't adjust the configuration files to change the variables that control VRS? :smartass:

Anyway,

I'll take a look at the link Ramsay posted and see what I can learn. :pilotfly:

Thanks

That's why we taxi, take off, land and taxi into the wind, always.

 

So, what you're saying is I can't adjust the configuration files to change the variables that control VRS? :smartass:

 

Anyway,

 

I'll take a look at the link Ramsay posted and see what I can learn. :pilotfly:

 

Thanks

I dont really taxi against the wind that much, the fact that most takeoffs are against the wind makes the percentage of downwind taxi and airtaxiing higher than against the wind.

This video most probably shows a VRS coming from quickstopping hard with at least no headwind or a downwind composant:

I dont really taxi against the wind that much, the fact that most takeoffs are against the wind makes the percentage of downwind taxi and airtaxiing higher than against the wind.

 

This video most probably shows a VRS coming from quickstopping hard with at least no headwind or a downwind composant:

If you can't get there without making a down wind taxi, take off and come at it from a direction that puts you into the wind.

That video was settling with power. You don't have to be descending perfectly vertical to be in your own rotor wash, you only have to be moving perpendicular to the rotor disk, which is the same thing you'd be doing in a vertical descent.

Watch the video and make note of where the rotor wash is going and which way the helicopter is going in relation to it. The pilot had good forward speed, but he changed the game when he pitched the nose up and turned forward into the equivalent of down.

that one is also a fine example of the dead mans curve as well as VRS.

if he had entered VRS outside the dead mans curve then he could have recovered.

plus doing the quick stop within the curve made this outcome more likely.

that one is also a fine example of the dead mans curve as well as VRS.

 

if he had entered VRS outside the dead mans curve then he could have recovered.

plus doing the quick stop within the curve made this outcome more likely.

The video name is Settling with Power, and in US it has been deemed the same thing as VRS for ever. I think FAA recently aknowledged settling with power as another issue, finally.

I wont go into discussion about the definition, as a long time pilot I know these discissions never end( just google in any forum).

Anyway, thrust me, its was VRS.

Settling with power ( the new interpretation) is simply trying to hover with less power than needed which isnt the case here. If it was, the helo woudnt start to sink that fast and the ground effect would at least helped a bit on the way down.

The VRS Entry and exits I did the other week for my civil ATPL was exactly as in the video except for having lot more altitude and no need to walk from the excercise :-)

http://www.copters.com/aero/settling.html

https://www.skybrary.aero/index.php/Vortex_Ring

From FAA Handbook:

Vortex ring state (formerly referenced as settling-with- power) describes an aerodynamic condition in which a helicopt

https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/media/hfh_ch11.pdf

that one is also a fine example of the dead mans curve as well as VRS.

 

if he had entered VRS outside the dead mans curve then he could have recovered.

plus doing the quick stop within the curve made this outcome more likely.

No, not really. Dead mans curve is a height -airspeed diagram connected to loss of engine power.

To be perfectly safe from VRS you might need more than the height velociry diagram. For twin engined helos as this one, not all helos even have one, and if they have, the heights given is not safe for VRS recovery.

[Edit]Adding some info here instead of making a new post:

For the Bell412:

For this method, an altitude of 500 ft or greater is considered to be necessary for recovery from minor VRS, and an altitude of 4,000 ft or more for more severe conditions.

Source: accident investigation https://www.mlit.go.jp/jtsb/eng-air_report/JA6817.pdf

We lost an 412 in an similar accident years ago.

500’ GND for an minor VRS, and the height velocity diagram sat 375’ GND:

No, not really. Dead mans curve is a height -airspeed diagram connected to loss of engine power.

To be perfectly safe from VRS you might need more than the height velociry diagram. For twin engined helos as this one, not all helos even have one, and if they have, the heights given is not safe for VRS recovery.

hah another chart to remember :) man i love helicopters :)

fixed wing guys twiddling with their mfd's have it so easy.

that one is also a fine example of the dead mans curve as well as VRS.

 

if he had entered VRS outside the dead mans curve then he could have recovered.

plus doing the quick stop within the curve made this outcome more likely.

If he had been cross checking his gauges he wouldn't have gotten into VRS to begin with.

If the camera hadn't been there he probably wouldn't have gotten into VRS. :music_whistling:

If you can't get there without making a down wind taxi, take off and come at it from a direction that puts you into the wind.

Doesnt really work that way. If you are at a bigger airport, like any of the four airforce bases I have been based on(or the other maybe 200-400 airports I’ve been to you land where you are supposed to land and then you taxi. In my case taxi on wheels for the two last helos I did fly and do fly.

If on skids you Hovertaxi, and there is absolutely no danger in hovertaxing downwind, unless the wind is above the limit for tail- or crosswind hover. You wont get into VRS when hovertaxi at the recommended height for your helo. The statement to only hover into wind is not valid.

Doesnt really work that way. If you are at a bigger airport, like any of the four airforce bases I have been based on(or the other maybe 200-400 airports I’ve been to you land where you are supposed to land and then you taxi. In my case taxi on wheels for the two last helos I did fly and do fly.

 

If on skids you Hovertaxi, and there is absolutely no danger in hovertaxing downwind, unless the wind is above the limit for tail- or crosswind hover. You wont get into VRS when hovertaxi at the recommended height for your helo. The statement to only hover into wind is not valid.

You do what you want there ace. :shocking:

*gets coat. TAXI :music_whistling:

Why the haste? The next round is on the house. :music_whistling:

Yes, and if you look at the safe levels in my other post(as per your link earlier), the safe level is set to 0.3 x Vih. 0.4 is amber meaning that you are closing in to the downwash and safety is slightly reduced. 0.3 x Vih for that R22 = 500fpm.

 

The VSI (vertical speed indicator) has some lag due to how it need to be built, and to be sure not getting above 500fpm due to the lag, the common sense tought at flying schools to students flying smaller lighter helos is 300fpm. Thats the reason you can read 300fpm in a lot of places.

However, this doesnt mean that you will get into VRS at 301fpm.

 

High risk of entering VRS will be reaching 0.6Vih or above, thats 900fpm, for that R22.

As a former R22 Flight Instructor I have something to say about this VRS myth.

In my times we are required to "show" the student a VRS situation, to demonstrate how it feels and how to recover from it. Of cause at a safe altitude :smilewink:.

But even close to max gross-weight with a tailwind, it wasn't that easy to get into that VRS situation. In fact, it requires a lot of intentional efforts to get into it.

I am pretty sure that it is really unlikely for a small to medium size helicopter to get into VRS under normal circumstances.

Of cause, there are some exceptions. If you do some kind of air work as a commercial pilot or a military pilot with less outside reference, or you need most of your concentration for your task and not being aware that other things getting out of control it may be possible but in my view still unlikely. But these are also no normal circumstances.

Settling with power is the most likely reason for all these crashes, while VRS is a common excuse and diverts from the actual pilot error.

Vibration at low-speed is a natural thing and coms from the transverse flow in the rotor system and is not automatically a sign of beginning VRS.

Also, during hover and slow speeds, there is always VRS at the rotor tips to some small degree.

So it is not a question of his existence, it is a questuíon how big the VRS gets and how much of the rotor disc is affected by the reduction of the angle of attack and the resulting loss of lift.

I am sure any RL Pilot has his experiences with something similar to settling with power in different situations. I remember my transition from the Bell 206 to the Hughes 500. It was nearly impossible for me to assume the actual approach speed without the instruments. I was always much faster than I thought, but luckily, in the end, there was enough power and rotor efficiency available to stop in a hover.

Especially in a PC simulator like DCS, where you have no feeling (body response) when it comes to acceleration or more important deceleration, VRS is nothing else as an excuse for the harder truth - Pilot error. And of cause VRS is this invisible suddenly hitting danger the hero pilot has to face on. :lol:

If you a Mi-8 pilot? That is a different story :music_whistling: Heavy transport helicopters with huge rotors and a hell of a downwash are more often subject to VRS. But in the end, when it comes to a crash you can't blame VRS. Its still a pilot error. :doh:

As a former R22 Flight Instructor I have something to say about this VRS myth.

 

In my times we are required to "show" the student a VRS situation, to demonstrate how it feels and how to recover from it. Of cause at a safe altitude :smilewink:.

 

But even close to max gross-weight with a tailwind, it wasn't that easy to get into that VRS situation. In fact, it requires a lot of intentional efforts to get into it.

 

I am pretty sure that it is really unlikely for a small to medium size helicopter to get into VRS under normal circumstances.

 

Of cause, there are some exceptions. If you do some kind of air work as a commercial pilot or a military pilot with less outside reference, or you need most of your concentration for your task and not being aware that other things getting out of control it may be possible but in my view still unlikely. But these are also no normal circumstances.

 

Settling with power is the most likely reason for all these crashes, while VRS is a common excuse and diverts from the actual pilot error.

 

Vibration at low-speed is a natural thing and coms from the transverse flow in the rotor system and is not automatically a sign of beginning VRS.

Also, during hover and slow speeds, there is always VRS at the rotor tips to some small degree.

So it is not a question of his existence, it is a questuíon how big the VRS gets and how much of the rotor disc is affected by the reduction of the angle of attack and the resulting loss of lift.

 

I am sure any RL Pilot has his experiences with something similar to settling with power in different situations. I remember my transition from the Bell 206 to the Hughes 500. It was nearly impossible for me to assume the actual approach speed without the instruments. I was always much faster than I thought, but luckily, in the end, there was enough power and rotor efficiency available to stop in a hover.

 

Especially in a PC simulator like DCS, where you have no feeling (body response) when it comes to acceleration or more important deceleration, VRS is nothing else as an excuse for the harder truth - Pilot error. And of cause VRS is this invisible suddenly hitting danger the hero pilot has to face on. :lol:

 

If you a Mi-8 pilot? That is a different story :music_whistling: Heavy transport helicopters with huge rotors and a hell of a downwash are more often subject to VRS. But in the end, when it comes to a crash you can't blame VRS. Its still a pilot error. :doh:

I'll comment the parts of your post in sequence:

1) Yes, its hard to hit the sweet spot. I know this from own experience, just as you do. Easiest way to enter for training is keeping the altitude and fly downwind and reduce speed and keeping the power on when going on the low side of the power curve so you dont loose altitude. Its a hit almost everytime. For the gross weight, you are safer the heavier you are(se my other posts, also in that link to a post in Another thread.

Its hard to hit the sweet spot for training, but if you fly reckless you might sooner or later hit it, if low level you in a really bad situation.

The risk level isnt set by me, its set by the numerous researchers in the subject.

2) DCS tends to exaggerate a lot of fenomens or risks. The gamers that doesnt know that much think they know and sets demands for the module builders to incorporate things...and than it gets unreallistic. Like the Engine failure of the Huey. Or the mast bumbing that could occur way yo easy in some manouvers. (maybe fixed now, I dont know.)

3) I am a military pilot, currently flying NH90. (earlier: AS332 Superpuma, BO105, Jet- and Longranger, Hughes 300. Started fixedwing 1990 and helos from 1995)

4) The heavier you are (higher downwash) the higher is the descent rate to enter VRS.

A R22 has a lower safe descent rate than a CH53. Thats facts, and is easy to prove.

[Edit]Had to go away in the middle of writing. You and I are saying the same thing, it isnt easy to hit the VRS sweet spot.

The "high risk" is set in the theoretical models, and one of the conditions that is included in the formula is that the lateral airspeed is within the limits in the model , thats means basically a maximum of the same as Vih(the theoretical downwash speed). This means for a lighter helo, not much speed. R22 Vih is 7.4m/s so lets say maximum 15knots airspeed probably less and around 10knots to really increase the chance of hitting VRS. When training this high up in the air, its hard to really hit the sweet spot. If doing it into the wind you might have to have a backwards ground speed. Having better instruments, as we have with grounsspeed information and a hover indicator makes it less hard but still not easy.

This is cut from a NASA report about VRS:

They molded the result from a few research results in the same diagram, all say about the same.

The VRS formula explained in this post: https://forums.eagle.ru/showpost.php?p=4180185&postcount=15

To make an add on to what I and CHPL is saying, there seem to be not that uncommon in this forum that people Think they know. Next part is convincing the module makers that their statement is right.

This is the Dunning-Kruger-effect:

The picture above, having some knowledge but quite high confidence.

The module makers, would like to please the gamers, of course.

Theres a risk that when one, or a few guys, says "you get VRS from 300fpm+20%torque", that we actuellay get that behaviour in DCS. Also, we dont get it "sometimes" as IRL, but we get it every time. When thats "true" in DCS, we have VRS each time we descend at 300fpm+ with low Power setting which is very far away from the real world.

But but, he’s a “Lead Farmer”. Sounds like an expert to me.

But but, he’s a “Lead Farmer”. Sounds like an expert to me.

Ohh! My last post was’nt supposed to be a slap on OP.

More a point to module makers to be aware of risks of getting wrong information and falling into the problem of myth’s. Also to any forum member to critically judge the own knowledge level: ”How much do I really know about this subject, and what parts do I think I know?”

(We also have some people floating around stating they are helo pilots not really being but in most cases, probably all I guess, “real” helo pilots can see through and disregard these, mostly providing corrupt info. I know the module makers also see.)

The above about critical review of information should be applied to all information, including what I state. ( I mostly use credible sources for each statement so it should be quite easy to validate).

Good lord; what a bunch of keyboard jockeys :argue: and chartologists. :vertag:

Good lord; what a bunch of keyboard jockeys :argue: and chartologists. :vertag:

I've got around 1200 hours in the real UH-1H, did plenty of crazy/stupid things, never been close to VRS.

How about you "keyboard jockey"?

If you read them carefully the "charts" can explain to you why you haven't said a single thing worth discussing.

- Bear

what a bunch of

One is a mil chopper pilot, the other an ex-chopper instructor. And your quals were?

Take it easy guys :smilewink:

It's all about passion :bash:, which makes it not easier at all.

And there is always a big difference between theory and practice.

I remember Frank Robinson (Founder of Robinson Helicopter) saying: " My biggest fault was to encourage my engineers to get their private helicopter license. After getting a helicopter pilot they would like to increase safety margins over the top."

But in the end, we all like to have the most realistic simulation that is possible. :thumbup: :thumbup: