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When an aircraft is descending, does any lift act on it? If yes, how?
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When descending , an aircraft never goes in free fall, even if negative angle of attack is large. Does that mean the net downward force is not gravity, but less than gravity, due to certain lift acting at all negative angle of attacks?
general-aviation
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Sachin Chaudhary
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When descending , an aircraft never goes in free fall, even if negative angle of attack is large. Does that mean the net downward force is not gravity, but less than gravity, due to certain lift acting at all negative angle of attacks?
general-aviation
asked 2 hours ago
Sachin Chaudhary
61
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Sachin Chaudhary is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
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up vote
1
down vote
favorite
up vote
1
down vote
favorite
When descending , an aircraft never goes in free fall, even if negative angle of attack is large. Does that mean the net downward force is not gravity, but less than gravity, due to certain lift acting at all negative angle of attacks?
general-aviation
asked 2 hours ago
Sachin Chaudhary
61
New contributor
Sachin Chaudhary is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
When descending , an aircraft never goes in free fall, even if negative angle of attack is large. Does that mean the net downward force is not gravity, but less than gravity, due to certain lift acting at all negative angle of attacks?
general-aviation
general-aviation
asked 2 hours ago
Sachin Chaudhary
61
New contributor
Sachin Chaudhary is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 hours ago
Sachin Chaudhary
61
New contributor
Sachin Chaudhary is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 hours ago
Sachin Chaudhary
61
New contributor
Sachin Chaudhary is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 hours ago
Sachin Chaudhary
61
asked 2 hours ago
Sachin Chaudhary
61
61
New contributor
Sachin Chaudhary is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Sachin Chaudhary is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Sachin Chaudhary is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
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5 Answers
5
active
oldest
votes
up vote
3
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You seem to be confusing angle of attack and pitch angle. The pitch refers the orientation of the aircraft: where is the nose pointing? The angle of attack is the angle of the wings relative to the incoming air stream. Both can take on any value independent of each other. For example, one could imagine an aircraft falling straight down, but wings level. The pitch angle is then zero, but the angle of attack is 90 degrees!
Similarly, the pitch angle can be negative for a continuous steady state descent (and often is for a steep descent). However, the aircraft will be descending even steeper than where the nose is pointing. The angle of attack (the angle between the pitch vector and the even steeper velocity vector) is still positive, because indeed some positive angle of attack is required to generate lift.
answered 2 hours ago
Sanchises
5,25811850
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up vote
2
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The short answer is Yes. In a "normal" descent, (i.e. wings level positive G) there will still be a positive AoA. All that needs to be done to initiate a descent from a state of equilibrium is to reduce a little power and adjust pitch nose down enough to maintain airspeed. The wings are still producing lift, just a little less lift than the weight of the aircraft that they are opposing.
If there is a large negative AoA as the question stated, (assuming wings level) the aircrew would experience negative G forces and the aircraft would accelerate downwards at 32 ft/sec squared, PLUS any additional downwards force produced by the wings as a result of the negative AoA. Suffice it to say that this would be a rather brief transitory state.
answered 1 hour ago
Michael Hall
16416
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Unless you’re flying some sort of unlimited aerobatic airplane capable of such rapid pitch changes that you can achieve a negative angle of attack, your angle of attack will always remain positive as the relative wind changes in direction when transitioning from straight and level to a descent. A descending airplane is subject to the same forces and loads as any other airplane is. However in descent, gravity does provide a component of its total which acts in the direction of other thrust forces, propelling the aircraft forward (this is also how a gilder works) as the potential energy of the airplane is siphoned off and converted into work to counteract aerodynamic drag forces.
answered 1 hour ago
Carlo Felicione
38.3k270143
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The Newton's second law of motion tells us that acceleration of object equals sum of forces acting on it divided by its mass. In a steady descent, an aircraft is not accelerating, it is just flying with a constant velocity pointing obliquely downward. Therefore the sum of forces acting on it must be zero.
Now there are four main forces acting on an airplane:
(Image from How It Flies, chapter 4 Lift, Thrust, Weight, and Drag)
While drag is slanted slightly upward in descent, and thrust might be depending on the resulting pitch attitude, in normal descent the only force with large upward component is still lift, and therefore it must still be almost equal to weight to get the forces in balance.
The lift is only decreased when initiating descent, so the plane needs to accelerate downward in order to change direction. However usually it only decreases by maybe 10–20%. If it decreased more, you'd surely notice: if it decreases to zero, you'll feel weightless (e.g. in the Vomit Comet) and if it went negative, you'd raise from your seat as the aircraft would be accelerating downward faster than free fall, but you only have gravity pulling you down, so you'd lag behind it.
Besides the above linked, you may also want to look at the chapter 2 Angle of Attack Awareness and Angle of Attack Management of the abovementioned How It Flies book, for detailed treatment of the relationship between Angle of Attack and pitch, and any other section too; it does quite a good job explaining the physics related to flying.
answered 37 mins ago
Jan Hudec
37.2k395180
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up vote
-2
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When you start a descent by reducing thrust, the angle of attack is still positive, and in the graph of lift It shows that for a positively cambered wing, it will still generate lift.
So in the end, the force driving the pland downwards is smaller that net Gravity.
answered 2 hours ago
Eros Zanchi
13
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Eros Zanchi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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1
Unless you really want to descend in a hurry, AOA will still be positive in a descent.
– Michael Hall
2 hours ago
Interesting graph, where did it come from? I agree with @MichaelHall. Normal descent in an airplane there will always be a positive angle of attack.
– 757toga
1 hour ago
It comes from my Principles of Flight theory book.
– Eros Zanchi
1 hour ago
That is a (typical) graph of coefficient of lift vs. angle of attack. It is, however, completely irrelevant to the question, because angle of attack is the dependent variable here. The aircraft is controlled to produce desired lift (specifically to balance the weight) and flies at whatever angle of attack produces that lift.
– Jan Hudec
59 mins ago
I think this graph demonstrates a wing with a positive camber will have a small coefficient of lift even at negative angles of attack. Although in normal flight profiles (such as a routine descent profile) you would not be operating with a negative angle of attack. Values for the graph construction are likely the product of engineering calculations.
– 757toga
34 mins ago
add a comment |Â
5 Answers
5
active
oldest
votes
5 Answers
5
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
3
down vote
You seem to be confusing angle of attack and pitch angle. The pitch refers the orientation of the aircraft: where is the nose pointing? The angle of attack is the angle of the wings relative to the incoming air stream. Both can take on any value independent of each other. For example, one could imagine an aircraft falling straight down, but wings level. The pitch angle is then zero, but the angle of attack is 90 degrees!
Similarly, the pitch angle can be negative for a continuous steady state descent (and often is for a steep descent). However, the aircraft will be descending even steeper than where the nose is pointing. The angle of attack (the angle between the pitch vector and the even steeper velocity vector) is still positive, because indeed some positive angle of attack is required to generate lift.
answered 2 hours ago
Sanchises
5,25811850
add a comment |Â
up vote
3
down vote
You seem to be confusing angle of attack and pitch angle. The pitch refers the orientation of the aircraft: where is the nose pointing? The angle of attack is the angle of the wings relative to the incoming air stream. Both can take on any value independent of each other. For example, one could imagine an aircraft falling straight down, but wings level. The pitch angle is then zero, but the angle of attack is 90 degrees!
Similarly, the pitch angle can be negative for a continuous steady state descent (and often is for a steep descent). However, the aircraft will be descending even steeper than where the nose is pointing. The angle of attack (the angle between the pitch vector and the even steeper velocity vector) is still positive, because indeed some positive angle of attack is required to generate lift.
answered 2 hours ago
Sanchises
5,25811850
add a comment |Â
up vote
3
down vote
up vote
3
down vote
You seem to be confusing angle of attack and pitch angle. The pitch refers the orientation of the aircraft: where is the nose pointing? The angle of attack is the angle of the wings relative to the incoming air stream. Both can take on any value independent of each other. For example, one could imagine an aircraft falling straight down, but wings level. The pitch angle is then zero, but the angle of attack is 90 degrees!
Similarly, the pitch angle can be negative for a continuous steady state descent (and often is for a steep descent). However, the aircraft will be descending even steeper than where the nose is pointing. The angle of attack (the angle between the pitch vector and the even steeper velocity vector) is still positive, because indeed some positive angle of attack is required to generate lift.
answered 2 hours ago
Sanchises
5,25811850
You seem to be confusing angle of attack and pitch angle. The pitch refers the orientation of the aircraft: where is the nose pointing? The angle of attack is the angle of the wings relative to the incoming air stream. Both can take on any value independent of each other. For example, one could imagine an aircraft falling straight down, but wings level. The pitch angle is then zero, but the angle of attack is 90 degrees!
Similarly, the pitch angle can be negative for a continuous steady state descent (and often is for a steep descent). However, the aircraft will be descending even steeper than where the nose is pointing. The angle of attack (the angle between the pitch vector and the even steeper velocity vector) is still positive, because indeed some positive angle of attack is required to generate lift.
answered 2 hours ago
Sanchises
5,25811850
edited 1 hour ago
answered 2 hours ago
Sanchises
5,25811850
answered 2 hours ago
Sanchises
5,25811850
answered 2 hours ago
Sanchises
5,25811850
5,25811850
add a comment |Â
add a comment |Â
up vote
2
down vote
The short answer is Yes. In a "normal" descent, (i.e. wings level positive G) there will still be a positive AoA. All that needs to be done to initiate a descent from a state of equilibrium is to reduce a little power and adjust pitch nose down enough to maintain airspeed. The wings are still producing lift, just a little less lift than the weight of the aircraft that they are opposing.
If there is a large negative AoA as the question stated, (assuming wings level) the aircrew would experience negative G forces and the aircraft would accelerate downwards at 32 ft/sec squared, PLUS any additional downwards force produced by the wings as a result of the negative AoA. Suffice it to say that this would be a rather brief transitory state.
answered 1 hour ago
Michael Hall
16416
add a comment |Â
up vote
2
down vote
The short answer is Yes. In a "normal" descent, (i.e. wings level positive G) there will still be a positive AoA. All that needs to be done to initiate a descent from a state of equilibrium is to reduce a little power and adjust pitch nose down enough to maintain airspeed. The wings are still producing lift, just a little less lift than the weight of the aircraft that they are opposing.
If there is a large negative AoA as the question stated, (assuming wings level) the aircrew would experience negative G forces and the aircraft would accelerate downwards at 32 ft/sec squared, PLUS any additional downwards force produced by the wings as a result of the negative AoA. Suffice it to say that this would be a rather brief transitory state.
answered 1 hour ago
Michael Hall
16416
add a comment |Â
up vote
2
down vote
up vote
2
down vote
The short answer is Yes. In a "normal" descent, (i.e. wings level positive G) there will still be a positive AoA. All that needs to be done to initiate a descent from a state of equilibrium is to reduce a little power and adjust pitch nose down enough to maintain airspeed. The wings are still producing lift, just a little less lift than the weight of the aircraft that they are opposing.
If there is a large negative AoA as the question stated, (assuming wings level) the aircrew would experience negative G forces and the aircraft would accelerate downwards at 32 ft/sec squared, PLUS any additional downwards force produced by the wings as a result of the negative AoA. Suffice it to say that this would be a rather brief transitory state.
answered 1 hour ago
Michael Hall
16416
The short answer is Yes. In a "normal" descent, (i.e. wings level positive G) there will still be a positive AoA. All that needs to be done to initiate a descent from a state of equilibrium is to reduce a little power and adjust pitch nose down enough to maintain airspeed. The wings are still producing lift, just a little less lift than the weight of the aircraft that they are opposing.
If there is a large negative AoA as the question stated, (assuming wings level) the aircrew would experience negative G forces and the aircraft would accelerate downwards at 32 ft/sec squared, PLUS any additional downwards force produced by the wings as a result of the negative AoA. Suffice it to say that this would be a rather brief transitory state.
answered 1 hour ago
Michael Hall
16416
edited 1 hour ago
answered 1 hour ago
Michael Hall
16416
answered 1 hour ago
Michael Hall
16416
answered 1 hour ago
Michael Hall
16416
16416
add a comment |Â
add a comment |Â
up vote
0
down vote
Unless you’re flying some sort of unlimited aerobatic airplane capable of such rapid pitch changes that you can achieve a negative angle of attack, your angle of attack will always remain positive as the relative wind changes in direction when transitioning from straight and level to a descent. A descending airplane is subject to the same forces and loads as any other airplane is. However in descent, gravity does provide a component of its total which acts in the direction of other thrust forces, propelling the aircraft forward (this is also how a gilder works) as the potential energy of the airplane is siphoned off and converted into work to counteract aerodynamic drag forces.
answered 1 hour ago
Carlo Felicione
38.3k270143
add a comment |Â
up vote
0
down vote
Unless you’re flying some sort of unlimited aerobatic airplane capable of such rapid pitch changes that you can achieve a negative angle of attack, your angle of attack will always remain positive as the relative wind changes in direction when transitioning from straight and level to a descent. A descending airplane is subject to the same forces and loads as any other airplane is. However in descent, gravity does provide a component of its total which acts in the direction of other thrust forces, propelling the aircraft forward (this is also how a gilder works) as the potential energy of the airplane is siphoned off and converted into work to counteract aerodynamic drag forces.
answered 1 hour ago
Carlo Felicione
38.3k270143
add a comment |Â
up vote
0
down vote
up vote
0
down vote
Unless you’re flying some sort of unlimited aerobatic airplane capable of such rapid pitch changes that you can achieve a negative angle of attack, your angle of attack will always remain positive as the relative wind changes in direction when transitioning from straight and level to a descent. A descending airplane is subject to the same forces and loads as any other airplane is. However in descent, gravity does provide a component of its total which acts in the direction of other thrust forces, propelling the aircraft forward (this is also how a gilder works) as the potential energy of the airplane is siphoned off and converted into work to counteract aerodynamic drag forces.
answered 1 hour ago
Carlo Felicione
38.3k270143
Unless you’re flying some sort of unlimited aerobatic airplane capable of such rapid pitch changes that you can achieve a negative angle of attack, your angle of attack will always remain positive as the relative wind changes in direction when transitioning from straight and level to a descent. A descending airplane is subject to the same forces and loads as any other airplane is. However in descent, gravity does provide a component of its total which acts in the direction of other thrust forces, propelling the aircraft forward (this is also how a gilder works) as the potential energy of the airplane is siphoned off and converted into work to counteract aerodynamic drag forces.
answered 1 hour ago
Carlo Felicione
38.3k270143
answered 1 hour ago
Carlo Felicione
38.3k270143
answered 1 hour ago
Carlo Felicione
38.3k270143
answered 1 hour ago
Carlo Felicione
38.3k270143
38.3k270143
add a comment |Â
add a comment |Â
up vote
0
down vote
The Newton's second law of motion tells us that acceleration of object equals sum of forces acting on it divided by its mass. In a steady descent, an aircraft is not accelerating, it is just flying with a constant velocity pointing obliquely downward. Therefore the sum of forces acting on it must be zero.
Now there are four main forces acting on an airplane:
(Image from How It Flies, chapter 4 Lift, Thrust, Weight, and Drag)
While drag is slanted slightly upward in descent, and thrust might be depending on the resulting pitch attitude, in normal descent the only force with large upward component is still lift, and therefore it must still be almost equal to weight to get the forces in balance.
The lift is only decreased when initiating descent, so the plane needs to accelerate downward in order to change direction. However usually it only decreases by maybe 10–20%. If it decreased more, you'd surely notice: if it decreases to zero, you'll feel weightless (e.g. in the Vomit Comet) and if it went negative, you'd raise from your seat as the aircraft would be accelerating downward faster than free fall, but you only have gravity pulling you down, so you'd lag behind it.
Besides the above linked, you may also want to look at the chapter 2 Angle of Attack Awareness and Angle of Attack Management of the abovementioned How It Flies book, for detailed treatment of the relationship between Angle of Attack and pitch, and any other section too; it does quite a good job explaining the physics related to flying.
answered 37 mins ago
Jan Hudec
37.2k395180
add a comment |Â
up vote
0
down vote
The Newton's second law of motion tells us that acceleration of object equals sum of forces acting on it divided by its mass. In a steady descent, an aircraft is not accelerating, it is just flying with a constant velocity pointing obliquely downward. Therefore the sum of forces acting on it must be zero.
Now there are four main forces acting on an airplane:
(Image from How It Flies, chapter 4 Lift, Thrust, Weight, and Drag)
While drag is slanted slightly upward in descent, and thrust might be depending on the resulting pitch attitude, in normal descent the only force with large upward component is still lift, and therefore it must still be almost equal to weight to get the forces in balance.
The lift is only decreased when initiating descent, so the plane needs to accelerate downward in order to change direction. However usually it only decreases by maybe 10–20%. If it decreased more, you'd surely notice: if it decreases to zero, you'll feel weightless (e.g. in the Vomit Comet) and if it went negative, you'd raise from your seat as the aircraft would be accelerating downward faster than free fall, but you only have gravity pulling you down, so you'd lag behind it.
Besides the above linked, you may also want to look at the chapter 2 Angle of Attack Awareness and Angle of Attack Management of the abovementioned How It Flies book, for detailed treatment of the relationship between Angle of Attack and pitch, and any other section too; it does quite a good job explaining the physics related to flying.
answered 37 mins ago
Jan Hudec
37.2k395180
add a comment |Â
up vote
0
down vote
up vote
0
down vote
The Newton's second law of motion tells us that acceleration of object equals sum of forces acting on it divided by its mass. In a steady descent, an aircraft is not accelerating, it is just flying with a constant velocity pointing obliquely downward. Therefore the sum of forces acting on it must be zero.
Now there are four main forces acting on an airplane:
(Image from How It Flies, chapter 4 Lift, Thrust, Weight, and Drag)
While drag is slanted slightly upward in descent, and thrust might be depending on the resulting pitch attitude, in normal descent the only force with large upward component is still lift, and therefore it must still be almost equal to weight to get the forces in balance.
The lift is only decreased when initiating descent, so the plane needs to accelerate downward in order to change direction. However usually it only decreases by maybe 10–20%. If it decreased more, you'd surely notice: if it decreases to zero, you'll feel weightless (e.g. in the Vomit Comet) and if it went negative, you'd raise from your seat as the aircraft would be accelerating downward faster than free fall, but you only have gravity pulling you down, so you'd lag behind it.
Besides the above linked, you may also want to look at the chapter 2 Angle of Attack Awareness and Angle of Attack Management of the abovementioned How It Flies book, for detailed treatment of the relationship between Angle of Attack and pitch, and any other section too; it does quite a good job explaining the physics related to flying.
answered 37 mins ago
Jan Hudec
37.2k395180
The Newton's second law of motion tells us that acceleration of object equals sum of forces acting on it divided by its mass. In a steady descent, an aircraft is not accelerating, it is just flying with a constant velocity pointing obliquely downward. Therefore the sum of forces acting on it must be zero.
Now there are four main forces acting on an airplane:
(Image from How It Flies, chapter 4 Lift, Thrust, Weight, and Drag)
While drag is slanted slightly upward in descent, and thrust might be depending on the resulting pitch attitude, in normal descent the only force with large upward component is still lift, and therefore it must still be almost equal to weight to get the forces in balance.
The lift is only decreased when initiating descent, so the plane needs to accelerate downward in order to change direction. However usually it only decreases by maybe 10–20%. If it decreased more, you'd surely notice: if it decreases to zero, you'll feel weightless (e.g. in the Vomit Comet) and if it went negative, you'd raise from your seat as the aircraft would be accelerating downward faster than free fall, but you only have gravity pulling you down, so you'd lag behind it.
Besides the above linked, you may also want to look at the chapter 2 Angle of Attack Awareness and Angle of Attack Management of the abovementioned How It Flies book, for detailed treatment of the relationship between Angle of Attack and pitch, and any other section too; it does quite a good job explaining the physics related to flying.
answered 37 mins ago
Jan Hudec
37.2k395180
answered 37 mins ago
Jan Hudec
37.2k395180
answered 37 mins ago
Jan Hudec
37.2k395180
answered 37 mins ago
Jan Hudec
37.2k395180
37.2k395180
add a comment |Â
add a comment |Â
up vote
-2
down vote
When you start a descent by reducing thrust, the angle of attack is still positive, and in the graph of lift It shows that for a positively cambered wing, it will still generate lift.
So in the end, the force driving the pland downwards is smaller that net Gravity.
answered 2 hours ago
Eros Zanchi
13
New contributor
Eros Zanchi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
1
Unless you really want to descend in a hurry, AOA will still be positive in a descent.
– Michael Hall
2 hours ago
Interesting graph, where did it come from? I agree with @MichaelHall. Normal descent in an airplane there will always be a positive angle of attack.
– 757toga
1 hour ago
It comes from my Principles of Flight theory book.
– Eros Zanchi
1 hour ago
That is a (typical) graph of coefficient of lift vs. angle of attack. It is, however, completely irrelevant to the question, because angle of attack is the dependent variable here. The aircraft is controlled to produce desired lift (specifically to balance the weight) and flies at whatever angle of attack produces that lift.
– Jan Hudec
59 mins ago
I think this graph demonstrates a wing with a positive camber will have a small coefficient of lift even at negative angles of attack. Although in normal flight profiles (such as a routine descent profile) you would not be operating with a negative angle of attack. Values for the graph construction are likely the product of engineering calculations.
– 757toga
34 mins ago
add a comment |Â
up vote
-2
down vote
When you start a descent by reducing thrust, the angle of attack is still positive, and in the graph of lift It shows that for a positively cambered wing, it will still generate lift.
So in the end, the force driving the pland downwards is smaller that net Gravity.
answered 2 hours ago
Eros Zanchi
13
New contributor
Eros Zanchi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
1
Unless you really want to descend in a hurry, AOA will still be positive in a descent.
– Michael Hall
2 hours ago
Interesting graph, where did it come from? I agree with @MichaelHall. Normal descent in an airplane there will always be a positive angle of attack.
– 757toga
1 hour ago
It comes from my Principles of Flight theory book.
– Eros Zanchi
1 hour ago
That is a (typical) graph of coefficient of lift vs. angle of attack. It is, however, completely irrelevant to the question, because angle of attack is the dependent variable here. The aircraft is controlled to produce desired lift (specifically to balance the weight) and flies at whatever angle of attack produces that lift.
– Jan Hudec
59 mins ago
I think this graph demonstrates a wing with a positive camber will have a small coefficient of lift even at negative angles of attack. Although in normal flight profiles (such as a routine descent profile) you would not be operating with a negative angle of attack. Values for the graph construction are likely the product of engineering calculations.
– 757toga
34 mins ago
add a comment |Â
up vote
-2
down vote
up vote
-2
down vote
When you start a descent by reducing thrust, the angle of attack is still positive, and in the graph of lift It shows that for a positively cambered wing, it will still generate lift.
So in the end, the force driving the pland downwards is smaller that net Gravity.
answered 2 hours ago
Eros Zanchi
13
New contributor
Eros Zanchi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
When you start a descent by reducing thrust, the angle of attack is still positive, and in the graph of lift It shows that for a positively cambered wing, it will still generate lift.
So in the end, the force driving the pland downwards is smaller that net Gravity.
answered 2 hours ago
Eros Zanchi
13
New contributor
Eros Zanchi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 1 hour ago
answered 2 hours ago
Eros Zanchi
13
New contributor
Eros Zanchi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 2 hours ago
Eros Zanchi
13
answered 2 hours ago
Eros Zanchi
13
13
New contributor
Eros Zanchi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Eros Zanchi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Eros Zanchi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
1
Unless you really want to descend in a hurry, AOA will still be positive in a descent.
– Michael Hall
2 hours ago
Interesting graph, where did it come from? I agree with @MichaelHall. Normal descent in an airplane there will always be a positive angle of attack.
– 757toga
1 hour ago
It comes from my Principles of Flight theory book.
– Eros Zanchi
1 hour ago
That is a (typical) graph of coefficient of lift vs. angle of attack. It is, however, completely irrelevant to the question, because angle of attack is the dependent variable here. The aircraft is controlled to produce desired lift (specifically to balance the weight) and flies at whatever angle of attack produces that lift.
– Jan Hudec
59 mins ago
I think this graph demonstrates a wing with a positive camber will have a small coefficient of lift even at negative angles of attack. Although in normal flight profiles (such as a routine descent profile) you would not be operating with a negative angle of attack. Values for the graph construction are likely the product of engineering calculations.
– 757toga
34 mins ago
add a comment |Â
1
Unless you really want to descend in a hurry, AOA will still be positive in a descent.
– Michael Hall
2 hours ago
Interesting graph, where did it come from? I agree with @MichaelHall. Normal descent in an airplane there will always be a positive angle of attack.
– 757toga
1 hour ago
It comes from my Principles of Flight theory book.
– Eros Zanchi
1 hour ago
That is a (typical) graph of coefficient of lift vs. angle of attack. It is, however, completely irrelevant to the question, because angle of attack is the dependent variable here. The aircraft is controlled to produce desired lift (specifically to balance the weight) and flies at whatever angle of attack produces that lift.
– Jan Hudec
59 mins ago
I think this graph demonstrates a wing with a positive camber will have a small coefficient of lift even at negative angles of attack. Although in normal flight profiles (such as a routine descent profile) you would not be operating with a negative angle of attack. Values for the graph construction are likely the product of engineering calculations.
– 757toga
34 mins ago
1
1
Unless you really want to descend in a hurry, AOA will still be positive in a descent.
– Michael Hall
2 hours ago
Unless you really want to descend in a hurry, AOA will still be positive in a descent.
– Michael Hall
2 hours ago
Interesting graph, where did it come from? I agree with @MichaelHall. Normal descent in an airplane there will always be a positive angle of attack.
– 757toga
1 hour ago
Interesting graph, where did it come from? I agree with @MichaelHall. Normal descent in an airplane there will always be a positive angle of attack.
– 757toga
1 hour ago
It comes from my Principles of Flight theory book.
– Eros Zanchi
1 hour ago
It comes from my Principles of Flight theory book.
– Eros Zanchi
1 hour ago
That is a (typical) graph of coefficient of lift vs. angle of attack. It is, however, completely irrelevant to the question, because angle of attack is the dependent variable here. The aircraft is controlled to produce desired lift (specifically to balance the weight) and flies at whatever angle of attack produces that lift.
– Jan Hudec
59 mins ago
That is a (typical) graph of coefficient of lift vs. angle of attack. It is, however, completely irrelevant to the question, because angle of attack is the dependent variable here. The aircraft is controlled to produce desired lift (specifically to balance the weight) and flies at whatever angle of attack produces that lift.
– Jan Hudec
59 mins ago
I think this graph demonstrates a wing with a positive camber will have a small coefficient of lift even at negative angles of attack. Although in normal flight profiles (such as a routine descent profile) you would not be operating with a negative angle of attack. Values for the graph construction are likely the product of engineering calculations.
– 757toga
34 mins ago
I think this graph demonstrates a wing with a positive camber will have a small coefficient of lift even at negative angles of attack. Although in normal flight profiles (such as a routine descent profile) you would not be operating with a negative angle of attack. Values for the graph construction are likely the product of engineering calculations.
– 757toga
34 mins ago
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