Weathervane into the wind (landing)
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Weathervane into the wind (landing)
Hy,
I have the following question:
let's say you're coming in to land with a slight crosswind from the right. Does an airplane like to weathervane into the wind? If yes, does that also happen on a crosscountry flight with a crosswind?
Thanks for any inputs,
W.K.
I have the following question:
let's say you're coming in to land with a slight crosswind from the right. Does an airplane like to weathervane into the wind? If yes, does that also happen on a crosscountry flight with a crosswind?
Thanks for any inputs,
W.K.
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When you are airborne, and assuming in balance, the aeroplane is already aligned with the wind. That is the definition of flying in balance.
In a crosswind approach, if you attempt to line the aircraft up with the runway early (i.e. making a wing-down approach), and then release the controls, then the aircraft will tend to turn back into the wind, i.e. back to where it was before you straightened up the nose.
Likewise, on a cross country flight with a crosswind (or without a crosswind for that matter), if you are in balance then the aircraft is lined up with the wind. If you fly out of balance, i.e. in a side-slip, the aeroplane will again return back to its original state of being lined up with the wind.
We tend not to use the word "weathercock" for this effect. Weathercocking is what happens on the ground - the difference being that on the ground it is the relationship between the fin and the undercarriage which causes weathercocking, in the air it is the relationship between the fin and the centre of gravity which causes the aeroplane to fly in balance. We call this directional stability.
FFF
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In a crosswind approach, if you attempt to line the aircraft up with the runway early (i.e. making a wing-down approach), and then release the controls, then the aircraft will tend to turn back into the wind, i.e. back to where it was before you straightened up the nose.
Likewise, on a cross country flight with a crosswind (or without a crosswind for that matter), if you are in balance then the aircraft is lined up with the wind. If you fly out of balance, i.e. in a side-slip, the aeroplane will again return back to its original state of being lined up with the wind.
We tend not to use the word "weathercock" for this effect. Weathercocking is what happens on the ground - the difference being that on the ground it is the relationship between the fin and the undercarriage which causes weathercocking, in the air it is the relationship between the fin and the centre of gravity which causes the aeroplane to fly in balance. We call this directional stability.
FFF
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in the air the aircraft will stay the way you point it, it will however drift sideways over the ground unlessyou do something about it.On landing you normally either point the aircraft of into the wind so it tracks down the runway, or you sideslip it to compensate (see the numerous threads on crosswind landings). On a cross country flight it does exactly the same thing and again you fly a heading slightly into wind to track the direction you want to.
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Likewise, on a cross country flight with a crosswind (or without a crosswind for that matter), if you are in balance then the aircraft is lined up with the wind
I know what you are saying HOWEVER if the above is taken literally then it would appear to imply that if you are flying in balance then you are facing the wind direction.....so if on a northerly track with a southerly wind would your aircraft really be facing the wind direction .....propably not !
Can't believe I am actually getting into this question .....arrrggh!!!
I know what you are saying HOWEVER if the above is taken literally then it would appear to imply that if you are flying in balance then you are facing the wind direction.....so if on a northerly track with a southerly wind would your aircraft really be facing the wind direction .....propably not !
Can't believe I am actually getting into this question .....arrrggh!!!
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This is why instructors must choose words carefully...
FFF said the aircraft was ALIGNED with the wind, which doesn't always mean the nose points at it! In your example unfazed, the wind would be blowing along a line tail to nose, so the aircraft is aligned with the wind, even if the nose is pointing exactly away from it.
Might help you if you imagine a small boat crossing a fast-flowing river. In order to track straight across from bank to bank, the boat must point upstream, to avoid being swept downstream by the current.
For the aircraft, the wind is like the river current as you fly from A to B (bank to bank)
FFF said the aircraft was ALIGNED with the wind, which doesn't always mean the nose points at it! In your example unfazed, the wind would be blowing along a line tail to nose, so the aircraft is aligned with the wind, even if the nose is pointing exactly away from it.
Might help you if you imagine a small boat crossing a fast-flowing river. In order to track straight across from bank to bank, the boat must point upstream, to avoid being swept downstream by the current.
For the aircraft, the wind is like the river current as you fly from A to B (bank to bank)
Weathervanes??
All this weathervane stuff is a load of weathercock and bull. Once you're airborne, there's no such thing as weathervaning or weathercocking! Once you're airborne, the wind cannot create any moment (roll, pitch, yaw) on the aircraft (excepting turbulence and wind-shear complications)
The aircraft will point wherever you choose it, relative to the airmass.
The only reason a weathervane/cock works is because it's fixed to the ground (which the aircraft isn't, except for the takeoff and landing roll - don't forget your ailerons
).
A
edited to say that if you think the aircraft has weathervaned into the wind on final approach or climb out, it's because you have done it with the controls
The aircraft will point wherever you choose it, relative to the airmass.
The only reason a weathervane/cock works is because it's fixed to the ground (which the aircraft isn't, except for the takeoff and landing roll - don't forget your ailerons
).A
edited to say that if you think the aircraft has weathervaned into the wind on final approach or climb out, it's because you have done it with the controls
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Sorry FFF don't agree with the way you have put this, the aircraft is always lined up with the airflow (as you say, as long as you are in balance), this is the air flowing past it. Wind is the air flowing over the ground and it has no direct influence on the aircraft in flight and the aircraft will not weathercock, the only effect on the aircraft that wind has is the aircrafts track over the ground. The time that you will weathercock into wind is when it is in contact with the ground, Take off, landing or taxi.
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To be fair Foxmoth, FFF did mention that 'weathercocking' only happens in contact with the ground and the airborne bit should really be called something else...
See my previous comments about choosing words carefully - leads to all sorts of arguments and misunderstandings . Question is, has Whiteknight understood the explanation and how technical did he want/ need to get to find the answer...
See my previous comments about choosing words carefully - leads to all sorts of arguments and misunderstandings
. Question is, has Whiteknight understood the explanation and how technical did he want/ need to get to find the answer...
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See my previous comments about choosing words carefully
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WhiteKnight,
When you are tracking down on a final approach with a crosswind then if you don't use the sideslip approach then what is happening?? You are crabbing into the wind right.
Same thing occurs during takeoff - as soon as the aircraft becomes airborne then it will want to crab into the wind and then some extra drift is layed off by steering a few degrees left or right to prevent drifting over the ground.
Now if you take off in a C152 then you will experience a lot of weathercocking because the aircraft is slow but less weathercocking will be experienced if your take off is in a 747 because there a lot faster and the wind will have less influence on a faster craft because most if not all of the wind it experiences is from itself......only a small amount of drift has to be laid of in faster aircraft.
When you are tracking down on a final approach with a crosswind then if you don't use the sideslip approach then what is happening?? You are crabbing into the wind right.
Same thing occurs during takeoff - as soon as the aircraft becomes airborne then it will want to crab into the wind and then some extra drift is layed off by steering a few degrees left or right to prevent drifting over the ground.
Now if you take off in a C152 then you will experience a lot of weathercocking because the aircraft is slow but less weathercocking will be experienced if your take off is in a 747 because there a lot faster and the wind will have less influence on a faster craft because most if not all of the wind it experiences is from itself......only a small amount of drift has to be laid of in faster aircraft.
