4 ms·

This is taught in basic flight school. Power is lift, not pitching up.

p_l 6y ago
The things that are covered in first chapters of flight theory textbook for pilots, but which confound otherwise very knowledgeable laymen, can be summarised as close to all of them ;)
- TeMPOraL 6y ago
  Any recommendations on the books? Because I'm definitely confounded. I assume that AoA=0 and flat wing (not a teardrop-shaped one) would not lift off despite increasing the engine power (assuming no wind). Is that correct? I'm very much confused by what you're saying - given that "lifting force on the wings is for most important flight regimes a function of speed and angle of attack", isn't it easier to change the AoA, by operating the control surfaces and pitching the plane, instead of adding or reducing speed?
  - TylerE 6y ago
    In takeoff and landing, the most critical phases of fight, the range of useable pitch is fairly narrow... too much and you bang the tail into the ground. Too little and you strike the prop. The way you’re taught to land you use the controls is basically backwards - the elevators (pitch) control speed. The throttle controls rate of descent.
  - mannykannot 6y ago
    A wing moving at its zero-lift-coefficient angle of attack will produce no lift, regardless of its speed. If it is at an AofA giving a positive lift coefficient, the lift will increase with speed. Consider taking off in a taildragger. You start the takeoff roll with the tail on the ground, giving an angle of attack close to that of a stall, but at some point before lifting off, you typically raise the tail, because you do not want to stagger into the air on the point of stalling. If you are flying level at a constant speed, and then raise the nose without changing the power, you will initially rise, but you have tilted the lift vector backwards, increasing its backwards component, so your thrust is no longer sufficient to maintain speed (it is the same as a car going from flat to uphill.) If you are on the back of the drag curve (where drag increases as you slow down), raising the nose can result in going into a descent. An aircraft in a straight steady climb weighs no more than when it is flying straight and level, but there are two factors to consider. Firstly, the angle of attack is relative to your trajectory, which is now tilted. Secondly, on account of that, the lift is now tilted back, so the wing must create more lift in order that its vertical component is equal to the weight. Therefore, the angle of attack itself needs to be increased (and even more if your climbing airspeed is going to be lower that the speed you were cruising at.) Putting it together: to go into a climb, you must increase your thrust (or 'get some back' by allowing the aircraft to slow down to reduce the drag, but that's not an option when you are going slowly.) Secondly, you must increase the angle of attack, but that happens as a consequence of adjusting the pitch of the aicraft to maintain the desired/correct speed.
    - gabereiser 6y ago
      >Putting it together: to go into a climb, you must increase your thrust (or 'get some back' by allowing the aircraft to slow down to reduce the drag, but that's not an option when you are going slowly.) Secondly, you must increase the angle of attack, but that happens as a consequence of adjusting the pitch of the aicraft to maintain the desired/correct speed. You’re assuming a lot here. It basically comes down to lift coefficient of the wings when a certain power magnitude of air is forced under them. This comes from thrust. Power. You can climb with power being perfectly level. You should NOT increase your angle of attack (this will induce stall as it increases drag). It’s weird, it’s backwards, but it’s physics. Pitching up increases drag and increases the angle of attack increasing your power requirements to stay at altitude. This is a video I found on YouTube from my local college: https://youtu.be/_SJpXQh2KCE https://youtu.be/_SJpXQh2KCE In aeronautical terms, Power as P comes from lift and drag, you assume it’s from the wings, when it’s the thrust from the engine providing the compressed airflow (because we’re going fast) under and over those wings. I’ve been flying simulators and aircraft most my life as a hobby (due to slight red green colorblindness, I couldn’t be a fighter pilot so I went into computers). One thing I always have friends try is just keep the Cessna straight and level, increase power, she’ll lift on her own when she reaches that sweet spot.
      - mannykannot 6y ago
        > You’re assuming a lot here. Actually, I am not. I am assuming only that, for an unstalled wing and a fixed flap setting at a given air density, lift increases with airspeed and also with angle of attack, plus Newtonian mechanics. Nothing here is contradicted by the video you linked to. > It basically comes down to lift coefficient of the wings when a certain power magnitude of air is forced under them. This appears to be gibberish. > Power as P comes from lift and drag, you assume it’s from the wings, when it’s the thrust from the engine providing the compressed airflow (because we’re going fast) under and over those wings. Ditto. > I’ve been flying simulators and aircraft most my life as a hobby. Well, I fly airplanes too. This just goes to show that you don't need to understand the physics of flight in order to learn how to pilot an airplane.
        6y ago

p_l 6y ago

The things that are covered in first chapters of flight theory textbook for pilots, but which confound otherwise very knowledgeable laymen, can be summarised as close to all of them ;)

TeMPOraL 6y ago
Any recommendations on the books? Because I'm definitely confounded. I assume that AoA=0 and flat wing (not a teardrop-shaped one) would not lift off despite increasing the engine power (assuming no wind). Is that correct? I'm very much confused by what you're saying - given that "lifting force on the wings is for most important flight regimes a function of speed and angle of attack", isn't it easier to change the AoA, by operating the control surfaces and pitching the plane, instead of adding or reducing speed?
- TylerE 6y ago
  In takeoff and landing, the most critical phases of fight, the range of useable pitch is fairly narrow... too much and you bang the tail into the ground. Too little and you strike the prop. The way you’re taught to land you use the controls is basically backwards - the elevators (pitch) control speed. The throttle controls rate of descent.
- mannykannot 6y ago
  A wing moving at its zero-lift-coefficient angle of attack will produce no lift, regardless of its speed. If it is at an AofA giving a positive lift coefficient, the lift will increase with speed. Consider taking off in a taildragger. You start the takeoff roll with the tail on the ground, giving an angle of attack close to that of a stall, but at some point before lifting off, you typically raise the tail, because you do not want to stagger into the air on the point of stalling. If you are flying level at a constant speed, and then raise the nose without changing the power, you will initially rise, but you have tilted the lift vector backwards, increasing its backwards component, so your thrust is no longer sufficient to maintain speed (it is the same as a car going from flat to uphill.) If you are on the back of the drag curve (where drag increases as you slow down), raising the nose can result in going into a descent. An aircraft in a straight steady climb weighs no more than when it is flying straight and level, but there are two factors to consider. Firstly, the angle of attack is relative to your trajectory, which is now tilted. Secondly, on account of that, the lift is now tilted back, so the wing must create more lift in order that its vertical component is equal to the weight. Therefore, the angle of attack itself needs to be increased (and even more if your climbing airspeed is going to be lower that the speed you were cruising at.) Putting it together: to go into a climb, you must increase your thrust (or 'get some back' by allowing the aircraft to slow down to reduce the drag, but that's not an option when you are going slowly.) Secondly, you must increase the angle of attack, but that happens as a consequence of adjusting the pitch of the aicraft to maintain the desired/correct speed.
  - gabereiser 6y ago
    >Putting it together: to go into a climb, you must increase your thrust (or 'get some back' by allowing the aircraft to slow down to reduce the drag, but that's not an option when you are going slowly.) Secondly, you must increase the angle of attack, but that happens as a consequence of adjusting the pitch of the aicraft to maintain the desired/correct speed. You’re assuming a lot here. It basically comes down to lift coefficient of the wings when a certain power magnitude of air is forced under them. This comes from thrust. Power. You can climb with power being perfectly level. You should NOT increase your angle of attack (this will induce stall as it increases drag). It’s weird, it’s backwards, but it’s physics. Pitching up increases drag and increases the angle of attack increasing your power requirements to stay at altitude. This is a video I found on YouTube from my local college: https://youtu.be/_SJpXQh2KCE https://youtu.be/_SJpXQh2KCE In aeronautical terms, Power as P comes from lift and drag, you assume it’s from the wings, when it’s the thrust from the engine providing the compressed airflow (because we’re going fast) under and over those wings. I’ve been flying simulators and aircraft most my life as a hobby (due to slight red green colorblindness, I couldn’t be a fighter pilot so I went into computers). One thing I always have friends try is just keep the Cessna straight and level, increase power, she’ll lift on her own when she reaches that sweet spot.
    - mannykannot 6y ago
      > You’re assuming a lot here. Actually, I am not. I am assuming only that, for an unstalled wing and a fixed flap setting at a given air density, lift increases with airspeed and also with angle of attack, plus Newtonian mechanics. Nothing here is contradicted by the video you linked to. > It basically comes down to lift coefficient of the wings when a certain power magnitude of air is forced under them. This appears to be gibberish. > Power as P comes from lift and drag, you assume it’s from the wings, when it’s the thrust from the engine providing the compressed airflow (because we’re going fast) under and over those wings. Ditto. > I’ve been flying simulators and aircraft most my life as a hobby. Well, I fly airplanes too. This just goes to show that you don't need to understand the physics of flight in order to learn how to pilot an airplane.
      - 6y ago