More bad physics - turns

[photofly]

By definition, lift directly opposes weight.

Um... no it doesn’t.

Lift absolutely increases in a turn. I think you had a brain fart there.

[AuxBatOn]

In level flight, it does.

[photofly]

You of all people should know the definition of lift has nothing to do with weight! Level or banked flight, has nothing to do with it.

[AuxBatOn]

You of all people should know the definition of lift has nothing to do with weight! Level or banked flight, has nothing to do with it.

In level flight, it opposes weight, as in, positive lift will counteract weight in some form. Sure, 90 deg AoB and you have exactly 0 lift....

[photofly]

In a 90 degree banked turn, you have a shit tonne of lift. It’s what pulls you around the turn.

[Conflicting Traffic]

By definition, lift directly opposes weight. Weight doesn’t change and you are not climbing therefore lift remains the same.

You can certainly define lift this way if you want to and if you're consistent about it, but it's unconventional, and I suspect it would lead to lots of unnecessary complications. Lift is normally defined as the component of aerodynamic force perpendicular to the relative airflow and in the aircraft's plane of symmetry.

[AuxBatOn]

By definition, lift directly opposes weight. Weight doesn’t change and you are not climbing therefore lift remains the same.

You can certainly define lift this way if you want to and if you're consistent about it, but it's unconventional, and I suspect it would lead to lots of unnecessary complications. Lift is normally defined as the component of aerodynamic force perpendicular to the relative airflow and in the aircraft's plane of symmetry.

The point remains: lift, drag and all aerodynamic forces that we self-define stem from really one sum of forces: the sum of all aerodynamic forces, regardless of where they originate. The moment those forces generate will dictate where, on the airplane, the force is deemed to act upon. The fact that some force originate from the elevator is irrelevant on this analysis.

When you put an aircraft model in a wind tunnel and define coefficients, you artificially define upon which axis the coefficients will be applicable (and thus define your conventions).

[digits_]

By definition, lift directly opposes weight. Weight doesn’t change and you are not climbing therefore lift remains the same.

You can certainly define lift this way if you want to and if you're consistent about it, but it's unconventional, and I suspect it would lead to lots of unnecessary complications. Lift is normally defined as the component of aerodynamic force perpendicular to the relative airflow and in the aircraft's plane of symmetry.

The point remains: lift, drag and all aerodynamic forces that we self-define stem from really one sum of forces: the sum of all aerodynamic forces, regardless of where they originate. The moment those forces generate will dictate where, on the airplane, the force is deemed to act upon. The fact that some force originate from the elevator is irrelevant on this analysis.

When you put an aircraft model in a wind tunnel and define coefficients, you artificially define upon which axis the coefficients will be applicable (and thus define your conventions).

With your definition of lift, why would the lift change when you are climbing? Your weight doesn't change while you're climbing either.

[AuxBatOn]

You can certainly define lift this way if you want to and if you're consistent about it, but it's unconventional, and I suspect it would lead to lots of unnecessary complications. Lift is normally defined as the component of aerodynamic force perpendicular to the relative airflow and in the aircraft's plane of symmetry.

The point remains: lift, drag and all aerodynamic forces that we self-define stem from really one sum of forces: the sum of all aerodynamic forces, regardless of where they originate. The moment those forces generate will dictate where, on the airplane, the force is deemed to act upon. The fact that some force originate from the elevator is irrelevant on this analysis.

When you put an aircraft model in a wind tunnel and define coefficients, you artificially define upon which axis the coefficients will be applicable (and thus define your conventions).

With your definition of lift, why would the lift change when you are climbing? Your weight doesn't change while you're climbing either.

In level flight I said... But you can either nitpick an arbitrary definition (which is my point) or understand that in reality, there is one aggregate aerodynamic force acting upon the aircraft. Sure you can split it by surface but for the analysis of a coordinated turn, there is no point in doing so, unless we get into a stability and control discussion.

[RedAndWhiteBaron]

This is not what "stable" means in the context of flight dynamics. A stable aircraft will return to it's trimmed angle of attack and trimmed slip angle (which ideally is zero). That's it. Stability doesn't require anything wrt straight and level.

Sorry - this is what I meant by a stable aircraft. You are correct. However, in a turn, there are aerodynamic forces working to return the plane to its trimmed AoA and slip angle. Although rotation has been established, and no, does not require acceleration to maintain it, it does require an aerodynamic force counteracting the force of drag (if you can call it that) working to restore stable flight.

This isn't true when we talk about the transition into the turn, which requires angular acceleration.

This speaks to my previous point - although no further acceleration is required to maintain the established attitude and rate of turn in a steady turn, there are forces at work attempting to restore the plane to stable flight. The more forward position of the centre of lift is what causes the force to prevent this.

By definition, lift directly opposes weight. Weight doesn’t change and you are not climbing therefore lift remains the same.

Lift remains the same in a climb too, else you would be accelerating upwards. You are not - you are moving upwards at a steady rate. The transition to the climb requires a brief period of increased lift, but once the climb has been established, lift is still equal to weight, unless you account for the now downwards component of drag (let's not split hairs over that definition yet though...) - which would require additional lift to overcome, although I believe this effect can be safely ignored for the purposes of this argument.

But, for the purposes of argument, sure, let us simplify lift to a single vector in a turn. It is not only greater by a proportion equal to the load factor (assuming a level turn or steady climb/descent), it is now more forward of the CoG than it was in stable flight. This cannot be accurately represented in a head-on view of an airplane.

It seems to me that this effect is a crucial factor to consider in a turn. Perhaps I'm wrong on that point, but clearly I don't think I am, or I wouldn't be making this argument. By ignoring this effect, the original pictures, while not wrong per se, are incomplete.

[photofly]

Why are you happy to ignore vertical component of drag in a turn ("I believe this effect can be safely ignored") but not movement of the centre of pressure? ("By ignoring this effect, the original pictures, while not wrong per se, are incomplete.")

That seems rather arbitrary to me. What's your basis for this?

[digits_]

In level flight I said... But you can either nitpick an arbitrary definition (which is my point) or understand that in reality, there is one aggregate aerodynamic force acting upon the aircraft. Sure you can split it by surface but for the analysis of a coordinated turn, there is no point in doing so, unless we get into a stability and control discussion.

Yes, you did. You wrote (my emphasis):

By definition, lift directly opposes weight. Weight doesn’t change and you are not climbing therefore lift remains the same.

Why did you add the emphasised part?
While not technically incorrect, you do heavily imply that with your definition of lift, the lift would not remain the same during a climb. Why? I don't see how.

[RedAndWhiteBaron]

Why are you happy to ignore vertical component of drag in a turn ("I believe this effect can be safely ignored") but not movement of the centre of pressure? ("By ignoring this effect, the original pictures, while not wrong per se, are incomplete.")

That seems rather arbitrary to me. What's your basis for this?

In a level turn (and in all level flight), there is no vertical component of drag, and I'm attempting to limit my argument to level turns to simplify it. Correct me if I'm wrong. I already barely understand my own argument

In a climb or descent, there is indeed vertical drag. I said "I believe this effect can be safely ignored for the purposes of this argument". Now, were we to argue over the finer points of the magnitude of lift involved in a climb, I would not ignore the effect.