LTE In the Hind

[Denwagg]

Turbulent downwash from main rotor also contributes to lte causing rotor blade stall especially wind blowing at 2oclock blowing that turbulent air

 Into the tail. I'm pretty sure this isn't modeled, no weathervaning either exam. landing downwind

 

This video pretty well says is all. Everything is opp for the hind because of clockwise main rotor blade direction

 

 

 

Edited August 28, 2021 by Denwagg

[Whisper]

It's pretty simple to see in-game : get near 14 main rotor pitch and watch your tail rotor not having enough power anymore to counteract main rotor, as much of the power is diverted to maintaining main rotor pitch. It happens consistently, at all altitude, and actually all weight.

It's not the result of interaction between main rotor airflow and tail rotor, nor interaction with wind, which are all listed as the causes of LTE in all documents listed above, it's more systematic than that. It's simply a lack of remaining power for the tail-rotor.

ED said they were looking into LTE but it was higly complex to model and would require quite some dev power. I'd guess if they had it done, they would have said it.

In the meantime, personally, I lighten my Hind so that I never need to go beyond 13 pitch for normal operations, and I only ever pass that limit when in forward speed enough to have forward airflow that keeps my Hind in check (usually when a high dose of lead and/or missile is flying toward me)

[gabuzomeu]

Actually, the naming is a bit confusing: Loss of Tailrotor Effectiveness describes a symptom, which can be resulting from different causes:

LTE aerodynamic effect or not having enough power to drive tail rotor ( and possibly other!)

Thus the difficult discussion.

 

[admiki]

6 hours ago, Whisper said:

It's pretty simple to see in-game : get near 14 main rotor pitch and watch your tail rotor not having enough power anymore to counteract main rotor, as much of the power is diverted to maintaining main rotor pitch. It happens consistently, at all altitude, and actually all weight.

It's not the result of interaction between main rotor airflow and tail rotor, nor interaction with wind, which are all listed as the causes of LTE in all documents listed above, it's more systematic than that. It's simply a lack of remaining power for the tail-rotor.

ED said they were looking into LTE but it was higly complex to model and would require quite some dev power. I'd guess if they had it done, they would have said it.

In the meantime, personally, I lighten my Hind so that I never need to go beyond 13 pitch for normal operations, and I only ever pass that limit when in forward speed enough to have forward airflow that keeps my Hind in check (usually when a high dose of lead and/or missile is flying toward me)

 

1 hour ago, gabuzomeu said:

Actually, the naming is a bit confusing: Loss of Tailrotor Effectiveness describes a symptom, which can be resulting from different causes:

LTE aerodynamic effect or not having enough power to drive tail rotor ( and possibly other!)

Thus the difficult discussion.

 

I don't know where this confusion about power comes from. Main and tailrotor are geared together, so there is no power separation between the two. IF main rotor RPM is maintained so is tail rotor RPM. Some tail rotors simply can not provide thrust needed to counter torque (thrust is not the same as power to drive rotor). That is Lack of Tailrotor Authority, not LTE.

[Hammer1-1]

7 hours ago, admiki said:

 

I don't know where this confusion about power comes from. Main and tailrotor are geared together, so there is no power separation between the two. IF main rotor RPM is maintained so is tail rotor RPM. Some tail rotors simply can not provide thrust needed to counter torque (thrust is not the same as power to drive rotor). That is Lack of Tailrotor Authority, not LTE.

Yeah when I google Lack of Tail Rotor Authority, take a guess what comes up....

[randomTOTEN]

Quote

c. Power Droop. A rapid power application may
cause a transient power droop to occur. Any decrease in main rotor rpm will cause a corresponding
decrease in tail rotor thrust. The pilot must anticipate this and apply additional left pedal to counter the main rotor torque. All power demands should be
made as smoothly as possible to minimize the effect of the power droop

page 8 of: https://www.faa.gov/documentLibrary/media/Advisory_Circular/ac90-95.pdf

 

I also suspect a large number of you are exceeding engine temp/torque limits because the simulation doesn't punish you for that just yet. It may be the case that the engines are more limiting than the tail rotor performance.

[admiki]

1 hour ago, Hammer1-1 said:

Yeah when I google Lack of Tail Rotor Authority, take a guess what comes up....

https://www.rotorandwing.com/2011/11/29/loss-of-tail-rotor-effectiveness-bell-206/

[Hammer1-1]

11 minutes ago, admiki said:

https://www.rotorandwing.com/2011/11/29/loss-of-tail-rotor-effectiveness-bell-206/

Ok so by his own definition, he describes it as LTE but states it should be called NETR. His opinion is 100% correct, but again it ties in to LTE.

[Hammer1-1]

1 hour ago, randomTOTEN said:

page 8 of: https://www.faa.gov/documentLibrary/media/Advisory_Circular/ac90-95.pdf

 

I also suspect a large number of you are exceeding engine temp/torque limits because the simulation doesn't punish you for that just yet. It may be the case that the engines are more limiting than the tail rotor performance.

Ok so what would be the most appropriate way to test and see if its LTE and not a combination of the aforementioned? From what Ive learned LTE is the root effect of ALL of the included forces that overpower the tail rotor INCLUDING mechanical limitations and environmental conditions. 

Edited August 29, 2021 by Hammer1-1

[fargo007]

58 minutes ago, Hammer1-1 said:

Ok so by his own definition, he describes it as LTE but states it should be called NETR. His opinion is 100% correct, but again it ties in to LTE.

 

That's not at all what it says. He is expressly stating that this is NOT LTE. 

 

Quote

 Any (single-rotor) helicopter can run out of pedal if torque is driven high enough and the RPM is dropped low enough. 

 

He calls it "NETR" also described by a USN pilot to us as "LTA" - Loss of tailrotor AUTHORITY.

 

In order for this to be proven as LTE and not a power issue as many are stating, you would have to show that it occurs with the helicopter under MGTOW, and is only reproducible with the specific wind circumstances that cause LTE.

 

To be clear - are you stating that you can reproduce the phenomenon under MGTOW and only with known LTE onset wind criteria?

 

Because neither I nor the pilots I fly with are able to do so.

[Hammer1-1]

Then let me ask you this: hot and humid day at altitude; your aircraft is around 70% max gross weight. Your collective is set at a higher than normal range due to atmospheric weather conditions and the wind is rear flanking 5m/s. What would be the main cause of LTE here? I left out aircraft speed and wind direction open for interpretation on purpose.

Edited August 29, 2021 by Hammer1-1

[admiki]

I am really confused why are you so adamant that it is LTE you are dealing with? 

You said hot, humid and high. And 70% MGTOW. Is that supposed to show us something? How hot? How humid? How high? You do realize that MGTW is not writen in stone. It changes with enviromental conditions. Are you sure that under your test conditions 70% is not over the MGTW for given conditions?

[fargo007]

22 hours ago, Hammer1-1 said:

Then let me ask you this: hot and humid day at altitude; your aircraft is around 70% max gross weight. Your collective is set at a higher than normal range due to atmospheric weather conditions and the wind is rear flanking 5m/s. What would be the main cause of LTE here? I left out aircraft speed and wind direction open for interpretation on purpose.

 

 

The question doesn't make sense on its face.

 

LTE is entirely dependent on wind direction, and it does not occur at speed.  

 

I still have an open question for you.

 

Quote

To be clear - are you stating that you can reproduce the phenomenon under MGTOW and only with known LTE onset wind criteria?

 

Because at its simplest, if you can make your circumstance happen in a zero wind mission, you are not experiencing LTE.  

[Rogue Trooper]

I have 2 weeks of holiday to set up my system, get voice attack going and fly the Hind.

Finally after such shameful negligence on my part (due to work of course)  I have time to give this big old girl some attention.

I am looking forward to experimenting with the Hind and seeing what is what, the hind feels like a great module but it would be interesting to see what is modelled and what I think is modelled.

Wind direction I know, however, Is there a specific wind speed that increases the risk of LTE on a chopper or is it just the faster the better!

Edited August 30, 2021 by Rogue Trooper

[fargo007]

46 minutes ago, Rogue Trooper said:

I have 2 weeks of holiday to set up my system, get voice attack going and fly the Hind.

Finally after such shameful negligence on my part (due to work of course)  I have time to give this big old girl some attention.

I am looking forward to experimenting with the Hind and seeing what is what, the hind feels like a great module but it would be interesting to see what is modelled and what I think is modelled.

Wind direction I know, however, Is there a specific wind speed that increases the risk of LTE on a chopper or is it just the faster the better!

 

 

There are a few circumstances that can cause it, and each for different reasons.

 

Each of them involve wind.

 

[Rogue Trooper]

I am well versed in the effects and what directions they affect the airframe, but do not remember any kind of wind speed values.

 

Without doubt the Hind runs out of pedal authority very quickly, it is very obvious at 4000 metres and this is with the Hind's automated system allowing full pedal deflection or should I say full yaw blade angle at these heights (no yaw AP).

 

Seriously wish I had the manual right now.

Edited August 30, 2021 by Rogue Trooper

[admiki]

48 minutes ago, Rogue Trooper said:

I am well versed in the effects and what directions they affect the airframe, but do not remember any kind of wind speed values.

 

Without doubt the Hind runs out of pedal authority very quickly, it is very obvious at 4000 metres and this is with the Hind's automated system allowing full pedal deflection or should I say full yaw blade angle at these heights (no yaw AP).

 

Seriously wish I had the manual right now.

 

Be sure to switch off SPUU52 if you want full pedal travel (that is not yaw AP channel).

[Rogue Trooper]

For sure.

I will let the automated systems dictate first then try without. (not yaw AP, no yaw AP in my test schedule... at all , only pitch and roll AP on, same as MI-8).

No hover hold junk or anything else..... Why would a pilot need such crap in the Hind?

Edited August 30, 2021 by Rogue Trooper

[Hammer1-1]

On 8/29/2021 at 4:17 PM, admiki said:

I am really confused why are you so adamant that it is LTE you are dealing with? 

You said hot, humid and high. And 70% MGTOW. Is that supposed to show us something? How hot? How humid? How high? You do realize that MGTW is not writen in stone. It changes with enviromental conditions. Are you sure that under your test conditions 70% is not over the MGTW for given conditions?

I left everything open to interpretation for a reason. At what point DOES it become LTE when you factor EVERYTHING in I just mentioned?

[Whisper]

Purely from a semantic point of view, it's LTA when you cannot order enough power to your tail rotor for it to do its job properly (you can't have Authority over your tail rotor anymore), and LTE when you can push enough power to the tail rotor, but conditions make its work useless (Tail rotor lost its Effectiveness).

Most if not all of what we witness with DCS Hind is LTA

Edited September 1, 2021 by Whisper

[fargo007]

On 8/31/2021 at 9:49 PM, Hammer1-1 said:

I left everything open to interpretation for a reason. At what point DOES it become LTE when you factor EVERYTHING in I just mentioned?

 

When it occurs with the specific wind conditions that induce LTE, and it doesn't occur without them. 

[Schlomo1933]

For me the spin starts only if iam in a hover to the right side. If I hover to the left all is okay. 
i don’t believe, that this behavior has something to do with LTA.

for me it feels like a bug 

Edited September 5, 2021 by Schlomo1933

[Rongor]

Probably we would need some performance diagrams to determine the specific MTOM for each current situation and all will be fine.

[Rogue Trooper]

unsure whether LTE is modelled.

Sometimes loss of tail rotor occurs and wind is involved, but I am unsure if I was aggressive when coming to a hover. It generally happens to me when slowing down but even less so recently.... possibly due to sim pilot experience or updates to the flight model.

On take off, I never experience it with wind... and I have tried many times to rotate my nose or tail into the wind.

 

I hope LTE is there.

 

[Slim_Kermie]

I have only seen this happen under three conditions:

1. Overweight at high altitude
2. Trim not reset before slowing to a hover
3. Turning in a very tight circle at speed and OGE

 

1 seems like LTA, 2 seems like the autopilot & flight control curves trying to murder me, and 3 definitely seems like some form of LTE.  LTE from wind direction might not be modeled, but you sure as heck can lose tail rotor effectiveness if you turn too quickly in the Hind.