How to gain altitude fast flaps full or not ?

[Piper_EEWL]

I can only echo Oliver here. Great explanation Esa!

Thanks

[Styggron]

errrrrr ok this I don't understand. If I am climbing I don't need more lift ? Is it because the throttle pulls me through faster if I increase it ? So I need less lift in a steady climb than straight and level ?Ok now I am utterly lost

I broke the issue down into two statements in the earlier post: the first one is the principle you need to realize, the second one is just to make it more accurate in all circumstances.

It comes from the elementary properties of nature and motion that you don't need more lift during climb. Airplanes are not different to any other body in this respect.

Consider an elevator (a lifting device, not control surface). Let it be stationary for a moment. That elevator hangs from its cable, which must support its weight by an equivalent, upwards pull force to balance out. Obviously.

If the elevator was going upwards at steady velocity ("rate of climb"), how would the force on the cable be? It must still be the same! Because the elevator's velocity is steady, the only thing the force of the cable must overcome is still the weight of the elevator, and that is unchanged. So the lifting force is also unchanged.

Vertical motion is not different to any other kind of motion: the body keeps on going at constant velocity (be it zero or not - it makes no difference) when the net force acting on it is zero - that happens if the forces acting on it are balanced. In our elevator, regardless of whether it was at rest or in steady motion, the cable pull must balance out the weight of the elevator, so the cable pull must be the same regardless of whether it was moving or not. Only to accelerate the elevator upwards must the force on the cable increase. That happens when the elevator starts moving, the force on the cable must momentarily be greater than the opposing weight to accelerate the elevator upwards but when it moves at constant rate, the force reduces to be equivalent to the elevator's weight. That's why you feel the pull when the elevator starts to go up, but nothing when it goes up at steady speed.

The airplane is no different to the elevator in this respect. When it climbs at steady rate, the vertical, upwards acting force must balance - and only just balance - the weight of the airplane. Only if we accelerate it upwards, "pull up", the force must be greater. Therefore one can say that the g-meter directly indicates the lift produced when the airplane is in the air. This is true in any attitude and in any kind of flight when the angle of attack is relatively small[*], not just when climbing or something.



The second statement in the earlier post is easy to understand if you realize the first. Only additional thing we need to account for is the definition of lift: in this case we could define that the lift is the component of aerodynamic force perpendicular to our direction of movement through the air. So, looking the airplane flying straight & level from its side, the lift would point towards "up", exactly balancing the weight that points "down", while the thrust points ahead horizontally - the drag, obviously, pointing into the opposite direction. Now, if you pitch the airplane up like in climb, the forces rotate with it: the lift tilts backwards and the thrust tilts upwards. Only the weight remains pointing down towards the centre of the Earth. Now, the thrust actually has some vertical component too, offsetting a bit of the weight - that's why the lift is actually reduced in the climb for the vertical forces together to remain in balance at a constant rate of climb! And that's why you need to add thrust in climb to keep the speed constant: now it doesn't only offset the drag, but it also needs to offset some of the weight too.

In an extreme example, imagine a fighter that steadily goes straight up vertically: now the lift in climb is actually zero! All the weight is supported by the thrust - which of course must also offset the drag, so quite high-performance airplane is required indeed.

I added the second statement earlier to account for this issue. And it is actually important to understand that the lift doesn't need to point up. Lift is not defined by any specific vertical, but by being perpendicular to the flow direction.



[*]Why only at small angles of attack? This comes from the definition of the lift, being perpendicular to the flight path through the air, whereas drag is opposite to the flight path vector. Let us just consider an airplane falling down in flat attitude, at its terminal velocity. The g-meter would indicate one g for the rate of descend is constant, but the force is by definition actually drag - not lift - in this case, even if it was "upwards": this is because it is acting opposite to our direction of movement through the air, we going directly downwards and the drag pointing upwards. Just like with a parachute!

Also, technically any sideways aerodynamic forces, when present, are lift too while not being indicated by the g meter.

But don't worry about these last notes, it has more to do with our definitions than actual understanding!

-Esa

Thank you for that. Read it over and over. Am starting to understand it thank you

I guess it is things like this (and cost) why I could never be a real pilot.

[DHenriques_]

errrrrr ok this I don't understand. If I am climbing I don't need more lift ? Is it because the throttle pulls me through faster if I increase it ? So I need less lift in a steady climb than straight and level ?Ok now I am utterly lost

I broke the issue down into two statements in the earlier post: the first one is the principle you need to realize, the second one is just to make it more accurate in all circumstances.

It comes from the elementary properties of nature and motion that you don't need more lift during climb. Airplanes are not different to any other body in this respect.

Consider an elevator (a lifting device, not control surface). Let it be stationary for a moment. That elevator hangs from its cable, which must support its weight by an equivalent, upwards pull force to balance out. Obviously.

If the elevator was going upwards at steady velocity ("rate of climb"), how would the force on the cable be? It must still be the same! Because the elevator's velocity is steady, the only thing the force of the cable must overcome is still the weight of the elevator, and that is unchanged. So the lifting force is also unchanged.

Vertical motion is not different to any other kind of motion: the body keeps on going at constant velocity (be it zero or not - it makes no difference) when the net force acting on it is zero - that happens if the forces acting on it are balanced. In our elevator, regardless of whether it was at rest or in steady motion, the cable pull must balance out the weight of the elevator, so the cable pull must be the same regardless of whether it was moving or not. Only to accelerate the elevator upwards must the force on the cable increase. That happens when the elevator starts moving, the force on the cable must momentarily be greater than the opposing weight to accelerate the elevator upwards but when it moves at constant rate, the force reduces to be equivalent to the elevator's weight. That's why you feel the pull when the elevator starts to go up, but nothing when it goes up at steady speed.

The airplane is no different to the elevator in this respect. When it climbs at steady rate, the vertical, upwards acting force must balance - and only just balance - the weight of the airplane. Only if we accelerate it upwards, "pull up", the force must be greater. Therefore one can say that the g-meter directly indicates the lift produced when the airplane is in the air. This is true in any attitude and in any kind of flight when the angle of attack is relatively small[*], not just when climbing or something.



The second statement in the earlier post is easy to understand if you realize the first. Only additional thing we need to account for is the definition of lift: in this case we could define that the lift is the component of aerodynamic force perpendicular to our direction of movement through the air. So, looking the airplane flying straight & level from its side, the lift would point towards "up", exactly balancing the weight that points "down", while the thrust points ahead horizontally - the drag, obviously, pointing into the opposite direction. Now, if you pitch the airplane up like in climb, the forces rotate with it: the lift tilts backwards and the thrust tilts upwards. Only the weight remains pointing down towards the centre of the Earth. Now, the thrust actually has some vertical component too, offsetting a bit of the weight - that's why the lift is actually reduced in the climb for the vertical forces together to remain in balance at a constant rate of climb! And that's why you need to add thrust in climb to keep the speed constant: now it doesn't only offset the drag, but it also needs to offset some of the weight too.

In an extreme example, imagine a fighter that steadily goes straight up vertically: now the lift in climb is actually zero! All the weight is supported by the thrust - which of course must also offset the drag, so quite high-performance airplane is required indeed.

I added the second statement earlier to account for this issue. And it is actually important to understand that the lift doesn't need to point up. Lift is not defined by any specific vertical, but by being perpendicular to the flow direction.



[*]Why only at small angles of attack? This comes from the definition of the lift, being perpendicular to the flight path through the air, whereas drag is opposite to the flight path vector. Let us just consider an airplane falling down in flat attitude, at its terminal velocity. The g-meter would indicate one g for the rate of descend is constant, but the force is by definition actually drag - not lift - in this case, even if it was "upwards": this is because it is acting opposite to our direction of movement through the air, we going directly downwards and the drag pointing upwards. Just like with a parachute!

Also, technically any sideways aerodynamic forces, when present, are lift too while not being indicated by the g meter.

But don't worry about these last notes, it has more to do with our definitions than actual understanding!

-Esa

Thank you for that. Read it over and over. Am starting to understand it thank you

I guess it is things like this (and cost) why I could never be a real pilot.

You're doing fine. The whole idea behind A2A and what we do here is to provide a product that's both educational and fun to use. From what I can see you're learning quite a lot and seem to be having a whale of a good time doing it.
Dudley Henriques

[Styggron]

You're doing fine. The whole idea behind A2A and what we do here is to provide a product that's both educational and fun to use. From what I can see you're learning quite a lot and seem to be having a whale of a good time doing it.
Dudley Henriques

I am indeed. Totally. It is loads of fun.

[AKar]

Not the best write-up, and a few illustrations could do much. I hope you could get something out of it.

I guess it is things like this (and cost) why I could never be a real pilot.

Many things are quite hard to gasp if there is no familiar framework for these things, so to speak, and it is quite rough road if taking many big topics at once. And not everyone who's new to aeronautics got the head-start of having studied physics or technology for instance, allowing some topics to feel immediately familiar. First steps are always difficult, to everyone! It is that one keeps on going that matters. Like with just about any topic, when the first pieces of understanding find their places, the picture in the puzzle starts to form and it gets easier thereon - and one can start digesting next challenges!

Also, I might add that many (or most even) of the topics I put emphasis on are not exactly along the path you'd go through if becoming a pilot (or so I understand), so don't allow them to be too intimidating from that point of view! Instead, I've devoted my time and interest to a journey that is, if anything, parallel to that one, studying how and why the aircraft are created and function like they do - or how and why they don't; and how the nature behaves when allowing us to take skies with our humble creations. That's one great personal journey also, benefiting much of great simulations likewise, and on to which I would invite anyone interested to join if I could. In particular, it is a journey about creativity of man, and his understanding of the world around us and of the limitations of himself and his creations when conquering the problems of flight ...but maybe even more about imagination of the nature herself, never running out of it when allowing us to stretch ours in this place provided for our lives and our flight!

-Esa

[Styggron]

Not the best write-up, and a few illustrations could do much. I hope you could get something out of it.

I guess it is things like this (and cost) why I could never be a real pilot.

Many things are quite hard to gasp if there is no familiar framework for these things, so to speak, and it is quite rough road if taking many big topics at once. And not everyone who's new to aeronautics got the head-start of having studied physics or technology for instance, allowing some topics to feel immediately familiar. First steps are always difficult, to everyone! It is that one keeps on going that matters. Like with just about any topic, when the first pieces of understanding find their places, the picture in the puzzle starts to form and it gets easier thereon - and one can start digesting next challenges!

Also, I might add that many (or most even) of the topics I put emphasis on are not exactly along the path you'd go through if becoming a pilot (or so I understand), so don't allow them to be too intimidating from that point of view! Instead, I've devoted my time and interest to a journey that is, if anything, parallel to that one, studying how and why the aircraft are created and function like they do - or how and why they don't; and how the nature behaves when allowing us to take skies with our humble creations. That's one great personal journey also, benefiting much of great simulations likewise, and on to which I would invite anyone interested to join if I could. In particular, it is a journey about creativity of man, and his understanding of the world around us and of the limitations of himself and his creations when conquering the problems of flight ...but maybe even more about imagination of the nature herself, never running out of it when allowing us to stretch ours in this place provided for our lives and our flight!

-Esa

Thank you Esa. I still learned a great deal from so many wonderful people such as your good self.