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Does the attitude change with a tail wind vs a head wind during an autorotation?


Guest Maximinious
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Only in the hover.

 

With a strong tailwind, you will have a lower nose attitude and rear cyclic, because the wind is trying to tip the tail up by getting under the synch elevator.

 

In forward flight, the nose attitude is consistent - it varies only with indicated airspeed, and doesn't care whether the package of air it is travelling in is moving over the ground in the same direction or the opposite.

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Max, you "sense"a different attitude, do you? And you have already been told you are wrong. It's true, you are wrong.

 

In the hover, you are maintaining a position over the ground, and the wind can be coming from any direction, so you will need to use differing cyclic positions and attitudes to prevent drift.

 

In forward flight, the only relative wind is from the front. and that is all that the aircraft reacts to. Attitude (and cyclic position) will vary with the Indicated Air Speed. The fact that the air mass is moving east, north, south-by-southwest or whatever doesn't have any effect on the aircraft attitude, it can only see the airflow coming straight at it.

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can anyone offer a better explanation?

Suppose you are flying above solid cloud and had no way to determine wind direction or speed. No matter what direction you fly, the cyclic force and aircraft attitude will be the same to maintain the same speed. The helicopter doesn't know which way the wind is blowing.

 

Do not confuse this situation with maneuvering with reference to the ground, where you use perceived ground speed to adjust your flight path. The helicopter still doesn't know which way the wind is blowing, but you are varying your airspeed to maintain a desired ground profile, such as a normal approach.

 

This is very confusing to those who are learning the basics of flying. For a really good presentation of wind drift considerations, try to find the book "Stick and Rudder" by Langweische. It deals with airplanes, but the principles are applicable to helos.

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The helicopter has no idea whether the wind is blowing or not, when in translational lift. Airspeed is airspeed, velocity through the air. Groundspeed is a different story, and it does take different power settings and attitudes to maintain the same groundspeed with different winds, but we're not talking about groundspeed, just airspeed. It's not uncommon for pilots to get into trouble while making close circles around a point when the wind is blowing, because they try to maintain the same groundspeed, because that's all they can see. You can't see airspeed without an airspeed indicator, and you can't maintain an airspeed without one. If you're looking outside, you sense groundspeed, but not airspeed.

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Why do I have to pull in more power to maintain the same altitude?

You don't.

 

You only need to pull more power while you are turning to offset the tilting of the lift force when you bank the helicopter. Once you roll out and are established in straight and level flight again, the power required is the same as when you were flying in the opposite direction.

 

After you roll out of the turn, let the airspeed and altitude stabilize for awhile, then look at your power. It should be the same. Headwind/tailwind makes no difference.

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I find it strange that you don't know this stuff and you say you are instructing? If the instructor does not understand these basics then what is being taught to the students?

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Turning always requires more power than straight and level flight, no matter which way you turn. The wind has nothing to do with it, it just requires more power to bank. The tighter the bank, the more power, and it's not linear, it's much higher. If you haven't learned this, how did you pass the written test?

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Guest Maximinious

I find it strange that you don't know this stuff and you say you are instructing? If the instructor does not understand these basics then what is being taught to the students?

 

.

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Guest Maximinious

I find it strange that you don't know this stuff and you say you are instructing? If the instructor does not understand these basics then what is being taught to the students?

 

Hey guys, principles of helicopters gave a great example. Quote: "When the helicopter is part of that block of air, the pilot does not "feel" the wind. This is shown clearly in a manned balloon. Once the balloon takes off it becomes part of the migrating mass of air. If one lights a candle while in the basket beneath the ballon, the flame stands more or less straight up, regardless of the velocity of wind. But if the balloon is tethered to the ground, the effect of wind becomes instantly apparent and the candle flame tilts downwind.

 

I think I was just being fooled by the ground reference aspect which in fact would cause what I experienced. I think I understood that but didn't really have anything to relate it to.

 

Trans... you should be giving me props instead of bashing me like you always try to do. A good instructor researches things he/she doesn't know so they can teach the correct concepts to their students. Thats why I am asking here on vertical reference.

 

I am really stressed out from thinking right now Tranny so maybe you can ask your mom if she can give me another auto-blow-tation so I can get on with my day. :D

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Trans... you should be giving me props instead of bashing me like you always try to do. A good instructor researches things he/she doesn't know so they can teach the correct concepts to their students. Thats why I am asking here on vertical reference.

 

Not bashing you and I certainly don't want to turn this thread into one of the last ones you started but I just find it strange that you don't have a grasp of this stuff as an instructor.

I'm not going to stoop to your usual level of trash talk either, if you need some tutoring on aerodynamics let me know, I'll do you a good deal! ;)

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