How to deal with severe yaw coming out of ETL?

Blah blah

Congratulations, you've written a page of text demonstrating you don't understand this topic. It also appears you lack the ability to listen, so I'm out.

Congratulations, you've written a page of text demonstrating you don't understand this topic. It also appears you lack the ability to listen, so I'm out.

Sorry, could not resist.

If the speed reduces the nose will not gradually turn on its own. If you want to maintain the ground track you have to constantly adjust the heading to compensate for the increasing drift due to the decreasing speed.

Hmmm...

Except...

There is another way to provide that force needed to counter the drift of the aircraft. Rather than - as you're suggesting happens - deliberately turn the nose into the apparent wind, the pilot could bank the plane and push in opposite rudder to keep the nose pointing in the direction wanted while maintaining the desired track. The lift from the wings would then counter the drift rather than a vector of the aircraft's thrust.

However, the reason you would have to push in opposite rudder while banked to maintain the desired track (more than is necessary to simply maintain altitude) is that if the aircraft is being held on track by the lift of the wings, the aircraft is not aligned with the apparent wind & the force of that unaligned airflow on the tail surfaces will cause it to yaw into the wind, and the rudder is needed to counter that yaw.

If the only way to maintain the track and not yaw is to bank into the wind and add opposite rudder, is it incorrect to say the nose wants to turn into the wind ?

"A goldfish doesn't care if or how fast (at a constant speed) his goldfish bowl is moving, same applies to planes. "

Because a goldfish not only doesn't know where it's going, it doesn't care where it's going - Which takes us all the way back to the beginning.

If you're not interested in where you are going on the surface of the earth, that's true.

If you are interested in where you're going (which is every single flight any human ever makes in an aircraft), you have to calculate the vector sum of your movement in the airmass, and the movement of the airmass relative to the ground to work out where you're going.

You are then explicitly interested in the motion of the air relative to the ground, or as it's often called, the wind.

"You (should) always turn by banking, not yawing."

I know, it's less efficient / more draggy to do otherwise.

The point is that it's possible to fly uncoordinated in a crosswind and not turn, and in doing so maintain a heading aligned with the ground track while flying in a crosswind, but you have to fight the yaw induced by the crosswind to do so.

Again - you have to fight the yaw induced by the crosswind to do so...

When slowing and 'making' those heading adjustments you mention - you bank - to counter the drift - then the asymmetric forces on the aircraft cause it to weathervane into the wind, and at the point where you believe you've been turned enough to fly coordinated with the desired TVV you stop banking.

It may be that to 'do the right thing' you push some rudder to stay coordinated, but if you didn't the end result would be the same - in banking to maintain track you would cause an asymmetric airflow and this ( the wind ) would cause you to weathervane to your new heading.

You are talking about two different things here.

 

1. If you want the plane to maintain the present ground track you need to adjust the heading to apply the necessary wind correction angle. You (should) always turn by banking, not yawing.

 

2. If you want to keep the track and the nose aligned with the track you need to perform a slip with aileron and opposite rudder.

 

If the plane is moving in a constant steady moving air mass it doesn't have any effect on the plane except its movement in relationship to the ground.

In testing for me flying the Mi8 with 100Kmh IAS wind feels like actually flying in a "column" of air that is moving relative to the ground also points 1 and 2 appear to hold true in the sim?

Thanks that reinforced the concept. :thumbup:

A goldfish doesn't care if or how fast (at a constant speed) his goldfish bowl is moving, same applies to planes.

Does DCS have gusty wind? :D

1. Yes. Btw, a perfect description. It's the same IRL and in every sim.

The kicker for me is to pick up with 150Kmh IAS* and find myself flying whilst not moving laterally relative to the ground from that point you can move relative to the ground but to do so you are manoeuvring in flight as opposed to hovering low speed manoeuvring with no wind.

2. Yes.

Will explore more, stuff the Gold Fish. :)

* not sure why IAS and wind speed are different in DCS

Talking about wind - this thread is drifting.

I didnt read all posts, some are talking about the same thing but with different views.

YAW = Angular movement around the vertical axis.

I have > 5K h on different helos, and quite some time on full flight sims(FFS).

I have not felt any beaviour on the DCS UH-1 that is very of, taking in count that the Full flight sims may cost 20.000.000+ Usd/ Euro. Ive flown FFS that behaves not as good as the DCS UH-1...

There are some parts you could make better but no biggies.

Taking of with a normal take off, performing a traffic pattern and then land again is very close to IRL. The spinal behaviour from real flying works directly on the this module.

I would guess that if someone has big problems with the yaw, he either has a bad joystick/yaw pedal setup or lacks understanding of real helicopter flying, or have made some changes to the “pedal trim” or yaw trim or what it is called.

Didn't observe any difference. However it seems that there's something else unusual going on with e.g. the F-5 when flying with a tail and a head wind.

 

Have to do more testing....

Resolved the wind speed issue here and discovered "Dynamic Wind" awesome. :pilotfly:

i think its a bug in the scripted nature of the event.

sometimes it happens sometimes it does not. and it seems to ignore pedal input.

it can feel even stranger on really windy days when it does it.

 

try hover taxing about at speeds near translational lift and you will notice it in the pedals. sometimes.

 

anyway it feels totally scripted. almost like you have dragged a skid on the ground and its dragging you round. (to high for that)

or its ignoring your right pedal as you increase collective to stop, then loads it on all at once and you yaw right. as you cross ETL. it seems to be in the swap from left to right pedal as you slow the helicopter and then increase collective. i think its yawing left so we press right pedal, get no response and put in more right pedal and then it loads on all at once.

 

anyway luckily it does not happen all that often and its easy to fix when it does it but its hard to diagnose.

 

you need to use the pedals a lot less in the huey than the mi-8

because you have to work the collective less. because the single engine is more responsive so finding the balance is easier.

 

but you have to work the cyclic more (no autopilot)

 

why the huey pilots going the other way find the mi-8 easier and harder to fly :)

so try working the collective and pedals less. don't let your mi-8 muscle memory take over :)

this is another way to avoid it happening so often.

As there is no scripted EFM (all Helicopters have to use EFM/PFM) it most certainly isn't related to the "scripted nature".

What may happen is a dynamic calculation result from specific environment variables (Air pressure/temperature, humidity) and/or the flight modeling (hydraulic modeling, lift, power available/transmission) gives a wrong or unexpected result...

I had the same usually when coming out off ETL on landing approach close to the ground, but also when passing very close and slow over a ridge or sharp bump in the ground model.

Feels like someone jerks the tail for a moment. I cannot pinpoint this behaviour. Sometimes it happens sometimes it doesn't.

If anyone can reproduce it predictably, we could file a bug.

As there is no scripted EFM (all Helicopters have to use EFM/PFM) it most certainly isn't related to the "scripted nature".

 

What may happen is a dynamic calculation result from specific environment variables (Air pressure/temperature, humidity) and/or the flight modeling (hydraulic modeling, lift, power available/transmission) gives a wrong or unexpected result...

 

I had the same usually when coming out off ETL on landing approach close to the ground, but also when passing very close and slow over a ridge or sharp bump in the ground model.

Feels like someone jerks the tail for a moment. I cannot pinpoint this behaviour. Sometimes it happens sometimes it doesn't.

 

If anyone can reproduce it predictably, we could file a bug.

I know this one and it seems to feel like the Inertial Dampers don't always work on the 60's technology that's fitted in the Huey. :P :music_whistling:

But yes it feels as if it's some delayed inertia that acts to yaw the Huey perhaps maybe from the loading on the rotor and ground effect I just don't know.

At about 38 second the turn seems almost complete then at about 40 seconds the nose moves right, I normally just step on it and carry on.

Thanks for the video Frag,

That's sort of the challenge, but it's easier to see when you are on a poker straight approach to a designated LZ.

Inevitably you are going to have to pull power in, and that is what pushes the nose right.

My solutions to this have been these:

1 - make the application of power earlier and more gradual.

2 - offset it with left pedal.

Doing these I'm able to hold a mostly straight line now coming in on a dead straight approach.

Shags, the Huey sits tail low in a hover, are you sure you aren't tail striking? :-)

Shags, the Huey sits tail low in a hover, are you sure you aren't tail striking? :-)

And you can easily check if a tailstrike happened by looking at the tailskid.

It was even visible in Multiplayer for squadron mates.

My guess is a miscalculation from the ground effect modeling and transition out of translational lift, as it also happened over ridges or elevated roads if you pass low and slow...

Edit ..and a tailstrike usually happens when you flare too hard while being low. I was already at a steady approach and past the initial decelaration.

Thanks for the video Frag,

 

That's sort of the challenge, but it's easier to see when you are on a poker straight approach to a designated LZ.

 

Inevitably you are going to have to pull power in, and that is what pushes the nose right.

 

My solutions to this have been these:

 

1 - make the application of power earlier and more gradual.

 

2 - offset it with left pedal.

 

Doing these I'm able to hold a mostly straight line now coming in on a dead straight approach.

Ah you mean this sort of yaw when landing?

In the other video I pretty much expect to be at hover at 38 seconds perhapes with a slight amount of drift (and 8 out of 10 times I would be) but sometimes you get whats best described as a delayed yaw as at about 40 seconds. this delayed yaw doesn't seem to be consistent although your more likely to get it after some hard manoeuvring and hard turns. I can also confirm it happens out of ground effect well at least for me. This "delayed yaw" also happened in 1.5.x as well but again I don't know enough and can't fly that well to say it should or should not be there.

I don't get it in the Gazelle I might have experienced it in the Mi8 but sometimes I'm just going nuts so it might well be something I'm doing with the Mi8. :D

I don't really see any there. That's pretty straight.

I mean the yaw that takes place when you are coming out of ETL and have to pull in power.

I don't really see any there. That's pretty straight.

 

I mean the yaw that takes place when you are coming out of ETL and have to pull in power.

:D

Okay I don't fixate on the ball it's a second or such behind so just use it for indication, what I attempt to do is keep the image of the cockpit and the world aligned and try to detect any yaw (roll and pitch also) of the aircraft that yaw is real time so as I see any movement I add correction I'm also pre-correcting (aka best guess based on experience) some of the input.

After a while you should find that most (pretty much most) of the correction you put in is an autonomous action and muscle memory kinda kicks in with out much high level thought about it.

How are you at with hovering? Do you pick a point and fixate on it??

<edit>

The other indicator I use is the sound of the rotor and turbine you can hear how the rotor load is changing by the sound of the blades and the load on the turbine by the whine it makes. Sometimes I just enjoy flying just by sight and sound and ignore the instruments kinda seat of the pants flying.

I'm good to go at this point. Very good at hovering.

The issue was I was waiting until too late to start pulling power and doing it very suddenly.

Planning it beforehand and going gradually is the medicine I needed. I'm still not as smooth as I am in the Mi-8 (like butta) , but pretty close.

 

That's one of the reasons why aircraft ( including helicopters - makes no difference from a lift point of view for them ) land and takeoff into the wind not with it.

 

If I may jump in here, that is not even on the list of reasons.

We land into the wind due to lift equation (L = .5 * Cl * r * V^2 * A). The wind adds up to our lift for safety and efficiency purposes.

Otherwise you'd need to go faster and use more runway. :)

Thanks.

I'm good to go at this point. Very good at hovering.

 

The issue was I was waiting until too late to start pulling power and doing it very suddenly.

Ah yes I find the less I correct the less there is to correct, usually.

Planning it beforehand and going gradually is the medicine I needed. I'm still not as smooth as I am in the Mi-8 (like butta) , but pretty close.

The Mi8 can be a hand full with AP off however it's interesting to feel the difference. :)

I might have experienced it in the Mi8 but sometimes I'm just going nuts so it might well be something I'm doing with the Mi8. :D

Per definition the yaw should be the other way on Mi-8 because the rotor turns the opposite way.

:D

 

Okay I don't fixate on the ball it's a second or such behind so just use it for indication,

Thats right: in final part of landing you shall not fly the ball centered. Instead you shall align the helo with the landing direction. This is important( IRL) if you loose your engine, so your land with the skids parallell to the ground and can glide on them. Failure to tho this can cause the helo to flip over instead of gliding.

Also, any wind from either side will cause the helo to lean L/R meaning in hover you cant center the ball. Also, actual center of gravity causes the helo to lean right or left, specially noticed on a teetering rotor like UH-1 has.

<edit>

The other indicator I use is the sound of the rotor and turbine you can hear how the rotor load is changing by the sound of the blades and the load on the turbine by the whine it makes. Sometimes I just enjoy flying just by sight and sound and ignore the instruments kinda seat of the pants flying.

That is actually one of the most important things, unless you fly IMC, which you actually shouldn't in the Huey.

Keep your eyes out the cockpit. Listen and "feel" the helicopter, while keeping your regular monitoring pattern off the instruments and indicators.

When you get used to it is one quick glance at the attitude/HSI/speed/height block and a regular quick glance at the performance indicators... After a while your brain simply acquires the whole "picture" and recognizes if there is "something off".

Unless that happens keep your eyes out of the cockpit.

Easier said than done. I am still struggling not to focus too much on the instruments on course changes, keeping altitude etc., but on approach, I have quick and rare peeks at speed and VVI and the rest is listening to the blades and turbine and watching the outside world.

If you have your muscle memory trained, it is nearly by instinct when and how much and how fast to pull collective and where to keep the nose pointing in anticipation of the movements.

One thing that is pretty reassuring, is to watch movies of Huey landings IRL. You soon notice, that most pilots in real life, also need to anticipate and correct the yaw, thus they more often than not need to correct pedal input, as well... And they have the benefit of feeling momentum and having peripheral vision!

After all the Huey is pretty much seats of the pants flying, with no stabilizing computers, control-dampers and what not. :)

 

Thats right: in final part of landing you shall not fly the ball centered. Instead you shall align the helo with the landing direction. This is important( IRL) if you loose your engine, so your land with the skids parallell to the ground and can glide on them. Failure to tho this can cause the helo to flip over instead of gliding.

Also, any wind from either side will cause the helo to lean L/R meaning in hover you cant center the ball. Also, actual center of gravity causes the helo to lean right or left, specially noticed on a teetering rotor like UH-1 has.

Finally my bird brain is taking some of it in. ;)

After all the Huey is pretty much seats of the pants flying, with no stabilizing computers, control-dampers and what not. :)

Works for me. :smilewink:

So what about this weird delayed yaw thing?

Or do we simply forget that it occurs in the FM?