Rotor failure when hover or lower speed

[Shawnbo]

Recently, I'm assuming since last patch because this has never happened before. When I'm trying to hover or slow speed usually at maybe 400ft or so all of a sudden the rotors make weird sound and I loose altitude that has been mostly not recoverable. I wasn't doing any weird maneuvers or anything. Just out of nowhere the rotor system goes nuts on me.

[Floyd1212]

They added VRS to the flight model in the past couple months. (Maybe 2 patches ago now?)  You can read up about it here.

https://en.wikipedia.org/wiki/Vortex_ring_state

[admiki]

Like Floyd said, that might be VRS, but short track from you would help us to help you

[104th_Money]

@Shawnbo

It definitely sounds like Vortex Ring State. I'm sure you are in a descent over about 400 fpm and less than 20-25 knots when this is happening. You are basically stalling the rotor blades by descending more or less straight down and it disrupts the airflow over the blades causing you to descend quite rapidly.

Best bet is as soon as you recognize the condition, lower collective slightly and push cyclic into the wind and reapply collective. You should recover quite rapidly. You can push cyclic any direction you want to really as long as its into the wind. The goal is to get the rotor disk in fresh air. I normally just push forward a bit and fly out of it although if there is a tail wind it could take a second or two longer. The key is to react quickly to the condition, especially at low altitudes. If you just try to pull more collective, you will only increase the condition.

 

Money

[Dallas88B]

On 8/16/2022 at 12:58 PM, Shawnbo said:

hover or slow speed usually at maybe 400ft or so all of a sudden the rotors make weird sound

I came across this video "AH 64D Vortex Ring State (VRS) & recovery techniques" https://www.youtube.com/watch?v=2I7PZAAiMhM from @Volk. 
He suggests method to recover (Vuichard Recovery) when you have very little altitude to work with. 

 

Edited August 17, 2022 by Dallas88B

[104th_Money]

@Dallas88B

I watched the video, the Vuichard Recovery method is really no different than the method I described except for the fact that he doesnt lower the collective. Not lowering the collective makes the rotor disk work harder to get into fresh air. The ultimate goal is to get the rotor disk into fresh air, any direction not into the wind will work and into the wind just takes a second or to longer. Fortunately the Apache shake gives you quite a bit of warning as its starting. As long as you act immediately with the correct inputs you will be able to fly it out just as you get into VRS. 

[Dallas88B]

@104th_Money

As I understand it the classic recovery is to lower the collective, cyclic in a direction usually pitching forward, gain air speed, this sheds the rotor tip vortices but at a loss of altitude.

The Vuichard Recovery differs from the classic technique, and somewhat from the technique you describe.

Claude Vichard says "you immediately pull up the collective to provide maximum available power, apply counter torque with the pedal (left pedal in Apache) to maintain your heading, and push the cyclic in the opposite direction (right for Apache) for a 15- to 20-degree bank."

(For a counter-clockwise main rotor system, you should bank to the right; while a clockwise-turning main rotor system requires a left bank to exit)

 

The average height loss during the recovery procedure is 20 to 50 feet, depending on the duration of the maneuver. Cool eh?

This is a really excellent article in which Vuichard and former Robinson chief flight instructor Tim Tucker tell how they brought the Vuichard Recovery technique to the world : Claude Vuichard & Tim Tucker tell the story behind the Vuichard Technique   https://verticalmag.com/features/claude-vuichard-tim-tucker-tell-the-story-behind-the-vuichard-technique/

Tim Tucker has a video from a presentation at RotorTech Australia 2018, held on the Sunshine Coast (that @Volk. linked in his YT video) that explains it too https://www.youtube.com/watch?v=euHFD

Edited August 25, 2022 by Dallas88B
added address for 104th

[JG11Preusse]

Strange .... i was a BO-105 PAH Pilat at German Army Aviation for many years and hovered 3 feet, 10 feet, 30 feet many different hights without any problems, sometimes for many minutes, what you f.e. also have to do, to send a HOT towards a tank.

Also low or very low speed made no problems.

You will engage huge problems, when you are hovering or flying with very low speed and engage a to high sinkrate.

Only way ro recover is to push your stick forward and fast gain speed, if altidude allwos that, otherwise crash

I also engaged this 2 times yesterday with DCS AH-64D, when trying to land on the neaby Aircraftcarrier and in my opinion that is not equal to the real behavior

[Poptart]

2 hours ago, JG11Preusse said:

You will engage huge problems, when you are hovering or flying with very low speed and engage a to high sinkrate.

I only get VRS with a high sink rate. Most of the time I see people forgetting the fact that as you decrease speed you get less translational lift. Thus when they slow down they also start sinking. You just need to be more careful about adding collective when you slow down.

Edited August 25, 2022 by Poptart

[JG11Preusse]

vor 57 Minuten schrieb Poptart:

I only get VRS with a high sink rate. Most of the time I see people forgetting the fact that as you decrease speed you get less translational lift. Thus when they slow down they also start sinking. You just need to be more careful about adding collective when you slow down.

 

that is also correct, more pitch then and you will get more problems. .. lower pitch gain speed, that is what we had to do, if this will happen, but it never happens. ... but i engaded that problem 2 time with the AH-64 after the patch without loosing altitude.

I was hovering at a constant altitude and tried to get smooth over the landing strip of this carrier.

In real i also could fly fast, pitch down, nose up, reaching the altidute i want to ,  then pitch up to stay there and land where ever 1 like to , its a little bit tricky at dcs, because its not real

 

Edited August 25, 2022 by JG11Preusse

[MAXsenna]

@JG11Preusse

Sorry for off topic, but I REALLY hope to see you in the BO-105 forums when it's released!  

[JG11Preusse]

vor 26 Minuten schrieb MAXsenna:

@JG11Preusse

Sorry for off topic, but I REALLY hope to see you in the BO-105 forums when it's released!  

I am there

[Poptart]

1 hour ago, JG11Preusse said:

, its a little bit tricky at dcs, because its not real

I agree. In a real helicopter you can feel the movement and react naturally.

[JG11Preusse]

Tried it now several times .. the problem comes alltime when hovering or flying slow for  a short time.

Everything ok .. then flying towards the carrier slow. sometimes i tried 25 kts, sometimes 35 kts, sometimes at a different speed ......... problem will not care what you are doing, it comes after a few minutres,, whatever you also do while this shot time.

Looks like a timer will bring up the problem.

This has to get fixed, otherwise a Heli is useless.

All in all, with yesterday tries ....... 7 times in a row the.

One time i landed on the carrier (maybe more fall down on its runway), because i was flying more fast towards it and was loosing height above it slowly.

So because i was faster at the target, i had more time to almost land normal.

AH-64 has at this issue a big problem

 

 

[Floyd1212]

Can you post a track file that others might be able to hop into and experience this the way you are?

Have you tried disabling the COLL channel of the SCAS altogether to see if you have better control of the collective on your own?

[Nealius]

11 hours ago, 104th_Money said:

any direction not into the wind

Any direction not into the wind and not into dirty air from the rotor. Someone more knowledgeable on the details can fill in what I'm missing, but direction of rotor matters--something about dirty air on one side of the disc from what I understand. In Vuichard with the Huey or Apache you slide right (or you could slide forwards or backwards but will lose altitude, particularly going forward). Try that in the Mi-8 or Hind, with a rotor that rotates opposite the Huey/Apache, and it won't work. You have to slide out left.

A lot of people write off Vuichard because "any direction will do" when they overlook the entire point of Vuichard: losing as little altitude as possible during recovery. If you've got plenty of altitude, dropping collective and nosing forward is fine. If you don't have that altitude, Vuichard.

Personally, I just find it easier to stick to one technique when on brain-stem power.

Edited August 26, 2022 by Nealius

[bradmick]

The point of vuichard, so far as I understand it, is to increase tail rotor thrust to help "pull" you out of the column of air in the direction of thrust, hence the application of left (or power pedal). The main rotor may be stalling, but the tail rotor definitely isn't. Left pedal will increase thrust and assist with directional control and the right cyclic will also serve to assist with this as well. Translating tendency is ever present, and you're using that to your advantage to effect a rapid recovery. 

[Nealius]

That's the mechanism, with the point being the rapid recovery. But that's just semantics, really 

[pii]

On 8/25/2022 at 4:37 PM, JG11Preusse said:

Tried it now several times .. the problem comes alltime when hovering or flying slow for  a short time.

Everything ok .. then flying towards the carrier slow. sometimes i tried 25 kts, sometimes 35 kts, sometimes at a different speed ......... problem will not care what you are doing, it comes after a few minutres,, whatever you also do while this shot time.

Looks like a timer will bring up the problem.

This has to get fixed, otherwise a Heli is useless.

All in all, with yesterday tries ....... 7 times in a row the.

One time i landed on the carrier (maybe more fall down on its runway), because i was flying more fast towards it and was loosing height above it slowly.

So because i was faster at the target, i had more time to almost land normal.

AH-64 has at this issue a big problem

 

 

Whatever you do don't try to land on a helo pad.  

It looks like you are new to this landing" thing. I also get what is happening to you but not as much once I learned more about landing and flying the apache. Also it is hard to tell when you are about to get into that state since we as virtual pilots can't feel the aircraft, like if you were in it. So you have to watch the numbers to stay out of VRS or react the second it starts to shake. 

Also make sure you have good controller, I had to invest in a virpil base to get the control I needed to land. What do you use for a stick?

I had a warthog and TM pedels and I had to remove the springs from Both and it made a WORLD of difference, and made me decide to get a newer base for the warthog stick

So practice paractice practice and make sure you have good controls. I'm not just saying it , I have litterally done nothing but landings since day one. Getting pretting good at them if I say so myself even with the VRS thing.

PS and don't forget its BETA and a work in progress. Happy flying!

Now I want to know what is all the new beeping from the ATT hold?

[JG11Preusse]

vor 21 Stunden schrieb pii:

Whatever you do don't try to land on a helo pad (no problem, alsp not at apron or runway, only carrier brings up this problem).  

It looks like you are new to this landing" thing ( no.. absolutely not). I also get what is happening to you but not as much once I learned more about landing and flying the apache. Also it is hard to tell when you are about to get into that state since we as virtual pilots (i am not only a virtual pilot, more than 2000 flighthours BO-105 PAH) can't feel the aircraft, like if you were in it. So you have to watch the numbers to stay out of VRS (Gauges/Indicators are my friend) or react the second it starts to shake (10 to 30 feet above a carrier, there is no room to react, as you should know). 

Also make sure you have good controller, I had to invest in a virpil base to get the control I needed to land. What do you use for a stick? (TM Warthog Hotas with green Spring + TM Pedals)

I had a warthog and TM pedels and I had to remove the springs from Both and it made a WORLD of difference, and made me decide to get a newer base for the warthog stick

So practice paractice practice and make sure you have good controls. I'm not just saying it , I have litterally done nothing but landings since day one. Getting pretting good at them if I say so myself even with the VRS thing.

PS and don't forget its BETA and a work in progress. Happy flying!

Now I want to know what is all the new beeping from the ATT hold?

IHi pii,

looks like you didnt read all my posts, because all your questions i allready answered,.

[pii]

42 minutes ago, JG11Preusse said:

IHi pii,

looks like you didnt read all my posts, because all your questions i allready answered,.

Well maybe not but your first part sure sounded like a newbie having control problems during a landing. 

guess not.

 

[Talvid]

On 8/15/2022 at 10:12 PM, Floyd1212 said:

They added VRS to the flight model in the past couple months. (Maybe 2 patches ago now?)  You can read up about it here.

https://en.wikipedia.org/wiki/Vortex_ring_state

I'm thinking this is why I keep crashing in mission2 of the MAD campaign after the first landing at the FARP.  I even jettisoned both fuel bubbles but still drifted down into the drink.