Loss of tail-rotor effectiveness (LTE)

[ghost84]

Hi,

 

I am missing fundamentals effect in the huey and in all other helicopter flight models regarding the tail rotor. In DCS you can mistreat the pedals and the helicopter all the time without worrying about LTE which takes away a huge part of the fun of mastering a helicopter.

Some information on wiki: https://en.wikipedia.org/wiki/Loss_of_tail-rotor_effectiveness

 

Here is a very good video showing LTE in a huey, with ground collision and damaging a skid

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[Jester986]

Link isn't working. And agreed it would be nice to have.

[razo+r]

...

 

fixed it for you

[msalama]

And agreed it would be nice to have.

 

LTE was certainly modelled when the bird was first released. I'm sure I experienced it myself a couple of times back then.

[ghost84]

I'm sure I experienced it myself a couple of times back then.

In which situations did you experience it?

[msalama]

Can't remember exactly, but I think there was a strongish tailwind going and I had my collective raised way up. Sorry to be so hazy, but it was literally years ago.

Edited May 30, 2019 by msalama

[iFoxRomeo]

Negative, LTE was never simulated in any DCS Helicopter. The Huey has a very weak Tailrotor. Together with strong tailwind you get problems.

 

Fox

[msalama]

No, you don't necessarily, you only seem to get them in certain specific circumstances. So how do you know it's not modelled?

[ghost84]

This quote comes from the FAA helicopter flying handbook https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/media/hfh_ch11.pdf page 11-19:

Unfortunately, the aerodynamic conditions that a helicopter is susceptible to are not explainable in black and white terms. LTE is no exception. There are a number of contributing factors but what is more important to understanding LTE are taking the contributing factors and couple them with situations that should be avoided. Whenever possible, pilots should learn to avoid the following combinations:

 

1. Low and slow flight outside of ground effect.
   
2. Winds from ±15º of the 10 o’clock position and probably on around to 5 o’clock position [Figure 11-11]
   
3. Tailwinds that may alter the onset of translational lift and translational thrust hence induce high power demands and demand more anti-torque (left pedal) than the tail rotor can produce.
   
4. Low speed downwind turns.
   
5. Large changes of power at low airspeeds.
   
6. Low speed flight in the proximity of physical obstructions that may alter a smooth airflow to both the main rotor and tail rotor.
   

Pilots who put themselves in situations where the combinations above occur should know that they are likely to encounter LTE. The key is to not put the helicopter in a compromising condition but if it does happen being educated enough to recognize the onset of LTE and be prepared to quickly react to it before the helicopter cannot be controlled.

Try flying the above combinations and share what you experience in DCS. I for myself was not been able to get into any trouble. The tail is rock solid stable at any time. The only thing you can encounter in DCS is running out of pedal when you are really heavy.

[msalama]

Right, not saying it is or isn't, just sharing my experiences as it comes to the early bird. Haven't actually flown the Huey in ages so cannot say how the current bird behaves.

[iFoxRomeo]

No, you don't necessarily, you only seem to get them in certain specific circumstances. So how do you know it's not modelled?

 

The old Bell Helicopters, even some more modern ones, don't have a strong Tailrotor. That makes them more prone to LTE. How can you see, that the Huey's Tailrotor is weak.... I don't want to break Forumrule 1.16.

 

I'm sure (though not 100%) one of the developers once wrote that the DCS Huey doesn't have LTE modeled.

I'll try to find it, but don't hold your breath.

 

Fox

[iFoxRomeo]

Here´s the post I meant:

 

 

1. How accurate is the flight model?

DCS: UH-1H Huey is based on the same flight dynamics modeling principles as other DCS aircraft, which we have termed “Advanced Flight Model” or AFM. Using this technology, the FM is created using physics-based real-time calculations of the forces and moments experienced by the aircraft as a summation of its major individual elements, such as the fuselage, rotor blades, skids, stabilizers, etc. The model does not rely on “canned” scripted behavior to recreate desired performance characteristics, but instead naturally produces them based on carefully tuned input data of the aircraft elements’ characteristics and the equations governing the dynamic effects they impart on the aircraft. This means the model produces almost every dynamic effect associated with conventional helicopter flight naturally and in real-time (with some limited exceptions in cases where real-time calculations are extremely difficult, such as complex LTE (loss of tail rotor effectiveness) conditions). However given that the product is currently still in Beta stage, fine-tuning of the FM continues to ensure it is as accurate as possible specifically to the aircraft being modeled, i.e. the UH-1H. We have been and continue to work with a number of actual or former Huey pilots that have been of great value is testing and tuning of the model.

__________________

- EB

https://forums.eagle.ru/showpost.php?p=1744396&postcount=3

 

 

from the DCS Huey FAQ

 

 

 

 

Fox

[Jester986]

So its a little misleading to say the Huey's tailrotor is weak. They did make upgrades like the strakes and fast fin to improve it so there was an issue but it's not that bad. A 206 has about the weakest tailrotor of any helicopter and you only get into trouble there if you're sloppy flying it. Here's a link to some pilots arguing about LTE. Feel free to make a profile and ask if the Huey is a problem...

 

http://helicopterforum.verticalreference.com/topic/21718-the-hudson-river-lte-accident/

 

That being said LTE is a thing and it would be nice to see it modeled. I just don't want to see it exagerated like VRS is in the Huey and Mi-8.

Edited June 3, 2019 by Jester986

[iFoxRomeo]

So its a little misleading to say the Huey's tailrotor is weak. They did make upgrades like the strakes and fast fin to improve it so there was an issue but it's not that bad. A 206 has about the weakest tailrotor of any helicopter and you only get into trouble there if you're sloppy flying it. Here's a link to some pilots arguing about LTE. Feel free to make a profile and ask if the Huey is a problem...

 

http://helicopterforum.verticalreference.com/topic/21718-the-hudson-river-lte-accident/

 

That being said LTE is a thing and it would be nice to see it modeled. I just don't want to see it exagerated like VRS is in the Huey and Mi-8.

Thank you, but in this case I don´t need to ask. I have my own experience with the Huey and have Friends who had LTE with a Huey.

 

 

How many Helicopters do have a "safe pedal margin" described in their Flight Manual?

Edited June 3, 2019 by iFoxRomeo

[Jester986]

Well we have different experiences in them then. Fair enough.

[Implicit]

As I'm approaching the end of my CPL(H), the total lack of wind effect on the tail rotor is also starting to bug me. Wind is a huge factor when flying helicopters, yet it's mostly a non-factor here.

- No weather cocking

- No mainrotor wash disturbance

- No Tail rotor VRS

 

In addition, it also feels like tail rotor drift is just a fixed value when IGE. You get the same amount of drift even in an auto with low low RPM.