winglets - do they work...
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Fair enough, but mere mortals such as myself it's probably the easiest way aircraft designers can explain it to us.
As far as aero engineers are concerned, for pilots, forward force = thrust or gravity.
As far as aero engineers are concerned, for pilots, forward force = thrust or gravity.
Arm out the window & Zap Brannigan
So when an aircraft is in a gliding decent what is producing the forward force keeping the aircraft moving through the air? It aint thrust gentlemen. It is the horizontal component of weight which is equal to drag. The same principle applies to the lift produced by some winglets.
So when an aircraft is in a gliding decent what is producing the forward force keeping the aircraft moving through the air? It aint thrust gentlemen. It is the horizontal component of weight which is equal to drag. The same principle applies to the lift produced by some winglets.
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Winglets, Do they work ??
judging by this image, i would say a resounding YES. note the vapour in the vorticies! there are NO vorticies from the wing at all, only from the tips of the winglets themselves. even the tips of the horizontal stabiliser has large vorticies, as do the outboard edge of the flaps.
judging by this image, i would say a resounding YES. note the vapour in the vorticies! there are NO vorticies from the wing at all, only from the tips of the winglets themselves. even the tips of the horizontal stabiliser has large vorticies, as do the outboard edge of the flaps.
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There is no horizontal component of weight. Weight does not vary in a vector diagram.
Maybe you mean the horizontal component of lift?
Or have I forgotten more about aerodynamics than I ever knew...
Maybe you mean the horizontal component of lift?
Or have I forgotten more about aerodynamics than I ever knew...
Fair enough Titan, I see where you're coming from; I guess it's really a drag reduction in any case. So are we saying that thrust is force produced by the powerplants?
As DeBurcs says though, it's not the horizontal plane you're talking about, it's the longitudinal axis of the aircraft in which the resolved component of weight does its sterling job of keeping us gliding.
As DeBurcs says though, it's not the horizontal plane you're talking about, it's the longitudinal axis of the aircraft in which the resolved component of weight does its sterling job of keeping us gliding.
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any object that is either rising or descending but not in the vertical plane, be it an aircraft, or bushbike rider up or down a hill, will have a forward or rearward component of gravity! (weight) which is unchanging.
if the aircraft is level, then weight will be perpendicular, with no forward or rearward component, and have No effect on its forward speed. if the aircraft is at 10 deg nose down, then the weight will have a 10 deg forward component, its this percentage of it weight that will cause it to accelerate. the reverse is true if its is nose up. (assuming nose up or down is identical to the direction of travel)
if the aircraft is level, then weight will be perpendicular, with no forward or rearward component, and have No effect on its forward speed. if the aircraft is at 10 deg nose down, then the weight will have a 10 deg forward component, its this percentage of it weight that will cause it to accelerate. the reverse is true if its is nose up. (assuming nose up or down is identical to the direction of travel)
DeBurcs
When I said Horizontal component of weight I was referring to the component of weight acting along the longitudinal axis of the aircraft. Bad choice of words on my part, sorry. All in all though it makes no difference to the point I was trying to make. Winglets don’t produce thrust. They produce lift.
When I said Horizontal component of weight I was referring to the component of weight acting along the longitudinal axis of the aircraft. Bad choice of words on my part, sorry. All in all though it makes no difference to the point I was trying to make. Winglets don’t produce thrust. They produce lift.
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404
Winglets reduce drag, so less thrust is required for the same IAS which equals $$ in the pocket for the operator..I doubt they provide much lift, especially since they are not postioned in a way that they could create much of it..
I think you will also find that Kinetic energy is the force which keeps the a/c in forward motion conducting a glide and as a result lift results accordingly. Interestingly enough if you go too fast in a glide, you create more drag, creating less distance, and if you go to slow, the weight takes advantage of you along with the drag.
Winglets reduce drag, so less thrust is required for the same IAS which equals $$ in the pocket for the operator..I doubt they provide much lift, especially since they are not postioned in a way that they could create much of it..
I think you will also find that Kinetic energy is the force which keeps the a/c in forward motion conducting a glide and as a result lift results accordingly. Interestingly enough if you go too fast in a glide, you create more drag, creating less distance, and if you go to slow, the weight takes advantage of you along with the drag.
At risk of putting on the thick glasses and lab coat, kinetic energy isn't a force, it's 1/2 mass by the square of velocity - a measure of the energy of motion of an object.
Weight is the force that keeps us gliding; the component of it resolved in the direction of flight does that, counterbalanced by drag and the component of lift in that plane. These forces reach an equilibrium and a steady glide ensues.
As the aircraft glides, potential energy (mass x gravitational constant x height) is converted into kinetic energy.
Drag varies as the square of the velocity, so gliding faster than the best glide speed quickly increases the drag and wastes a lot of potential energy.
Take it away Professor Julius Sumner Miller!
Weight is the force that keeps us gliding; the component of it resolved in the direction of flight does that, counterbalanced by drag and the component of lift in that plane. These forces reach an equilibrium and a steady glide ensues.
As the aircraft glides, potential energy (mass x gravitational constant x height) is converted into kinetic energy.
Drag varies as the square of the velocity, so gliding faster than the best glide speed quickly increases the drag and wastes a lot of potential energy.
Take it away Professor Julius Sumner Miller!
4SPOOLED
I am very well aware that winglets reduce induced drag and the theory behind it. Please have a read of all my posts again. I was responding to a post that was saying that winglets produce thrust. I simply responded that they don’t, they produce a small component of lift in the direction of flight.
Please tell me you are kidding with this statement??
Arm out the window
You are correct. Weight is the force. KE is not a force and doesn’t belong in a forces diagram.
I am very well aware that winglets reduce induced drag and the theory behind it. Please have a read of all my posts again. I was responding to a post that was saying that winglets produce thrust. I simply responded that they don’t, they produce a small component of lift in the direction of flight.
I think you will also find that Kinetic energy is the force which keeps the a/c in forward motion conducting a glide and as a result lift results accordingly.
Arm out the window
You are correct. Weight is the force. KE is not a force and doesn’t belong in a forces diagram.
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Kinetic energy is the force describing an object in motion. Weight and lift may be componants of this, but the total energy is desribed as kinetic energy.
You are also correct in your interpretation AOOW......
You are also correct in your interpretation AOOW......
It all depends on how we commonly think about lift, I guess.
If you define it (correctly I think) as the component of an aerofoil's total reaction vector that is perpendicular to the relative airflow (and drag as the parallel component), then 404Titan's description of lift being produced by winglets is right.
Depending on where the relative airflow is coming from (could be anywhere depending on what you're doing) then lift can point anywhere too.
The tip vortices combined with the aircraft's velocity would cause the relative airflow striking the winglets to be from a forward, outboard direction, so the total reaction vector produced by the winglets should be able to be resolved with a forward-facing component.
4 Spooled, kinetic energy is definitely NOT a force, it's a property of a moving body that is a measure of how much work that body could do at a particular time.
A force is something that pushes or pulls something else; energy is, as I say, a measure of how much work something could do.
If you define it (correctly I think) as the component of an aerofoil's total reaction vector that is perpendicular to the relative airflow (and drag as the parallel component), then 404Titan's description of lift being produced by winglets is right.
Depending on where the relative airflow is coming from (could be anywhere depending on what you're doing) then lift can point anywhere too.
The tip vortices combined with the aircraft's velocity would cause the relative airflow striking the winglets to be from a forward, outboard direction, so the total reaction vector produced by the winglets should be able to be resolved with a forward-facing component.
4 Spooled, kinetic energy is definitely NOT a force, it's a property of a moving body that is a measure of how much work that body could do at a particular time.
A force is something that pushes or pulls something else; energy is, as I say, a measure of how much work something could do.
4SPOOLED
I guess I will have to through away all my aviation text books like Aerodynamics for Naval Aviators (NAVWEPS), The Advanced pilots Flight Manual, Handling the Big Jets, all my ATPL notes, CPL and PPL text books from Trevor Tom and my high school physics text books because they all must be wrong. What I don’t understand is how could all these people be so wrong?
PHYSICS LESSON 101.
For the record Kinetic energy is the energy of motion. An object which has motion - whether it be vertical or horizontal motion - has kinetic energy.
KE = ½ * m *v²
Where m = mass of object
v = speed of object
Potential Energy
An object can store energy as the result of its position. For example, the heavy heavy ball of a demolition machine is storing energy when it is held at an elevated position. This stored energy of position is referred to as potential energy. Similarly, a drawn bow is able to store energy as the result of its position.
PEgrav = mass * g * height
PEgrav = m * g * h
In the above equation, m represents the mass of the object, h represents the height of the object and g represents the acceleration of gravity (approximately 10 m/s/s on Earth).
Force and acceleration
F=ma
When an object changes speed (accelerates or decelerates),its shape or direction of motion, a force is acting on it. The formula for force is given below.
F=mass(kg) X acceleration(m/s/s)
The unit of force is called the newton.
A 100 kg person standing on wooden floor boards exerts a force of 1000 newtons on the floor.
In flight when the object stops accelerating the forces are in equilibrium.
I guess I will have to through away all my aviation text books like Aerodynamics for Naval Aviators (NAVWEPS), The Advanced pilots Flight Manual, Handling the Big Jets, all my ATPL notes, CPL and PPL text books from Trevor Tom and my high school physics text books because they all must be wrong. What I don’t understand is how could all these people be so wrong?
PHYSICS LESSON 101.
For the record Kinetic energy is the energy of motion. An object which has motion - whether it be vertical or horizontal motion - has kinetic energy.
KE = ½ * m *v²
Where m = mass of object
v = speed of object
Potential Energy
An object can store energy as the result of its position. For example, the heavy heavy ball of a demolition machine is storing energy when it is held at an elevated position. This stored energy of position is referred to as potential energy. Similarly, a drawn bow is able to store energy as the result of its position.
PEgrav = mass * g * height
PEgrav = m * g * h
In the above equation, m represents the mass of the object, h represents the height of the object and g represents the acceleration of gravity (approximately 10 m/s/s on Earth).
Force and acceleration
F=ma
When an object changes speed (accelerates or decelerates),its shape or direction of motion, a force is acting on it. The formula for force is given below.
F=mass(kg) X acceleration(m/s/s)
The unit of force is called the newton.
A 100 kg person standing on wooden floor boards exerts a force of 1000 newtons on the floor.
In flight when the object stops accelerating the forces are in equilibrium.
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Correct.
Kinetic energy, as the name suggests, is an energy.
Weight is a force despite the fact it is usually measured in Kgs (a unit of mass) these days.
Since weight does not act perpendicular to the aircraft longitudinal and lateral axes in a descent, its sum is not reduced as it is for lift. But it does have a resolved component (as the guys said previously) in the same direction as the longitudinal axis which when added to the (reduced) thrust value, equals the drag value.
Thus the aircraft is descending and in equilibrium.
This is basic physics and the understanding of which is something airlines expect from pilots. It is surprising how many pilots have not learnt this at school.
As for winglets, they do not produce thrust. Some winglets produce lift with a forward vector, the orientation of which depends on the amount of toe (the angle of attack of the winglet in relation to the relative airflow) given to the winglet. This vector value adds to the thrust produced by the engines allowing a performance saving to be made, usually realised in a reduced fuel burn for the same speed.
I now see 404titan has also mentioned the force/mass comparison. I'll leave mine in as I don't want the fingertip and brain strain to have been for nothing.
Kinetic energy, as the name suggests, is an energy.
Weight is a force despite the fact it is usually measured in Kgs (a unit of mass) these days.
Since weight does not act perpendicular to the aircraft longitudinal and lateral axes in a descent, its sum is not reduced as it is for lift. But it does have a resolved component (as the guys said previously) in the same direction as the longitudinal axis which when added to the (reduced) thrust value, equals the drag value.
Thus the aircraft is descending and in equilibrium.
This is basic physics and the understanding of which is something airlines expect from pilots. It is surprising how many pilots have not learnt this at school.
As for winglets, they do not produce thrust. Some winglets produce lift with a forward vector, the orientation of which depends on the amount of toe (the angle of attack of the winglet in relation to the relative airflow) given to the winglet. This vector value adds to the thrust produced by the engines allowing a performance saving to be made, usually realised in a reduced fuel burn for the same speed.
I now see 404titan has also mentioned the force/mass comparison. I'll leave mine in as I don't want the fingertip and brain strain to have been for nothing.
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Its easy to google these and get a result, but you still dont understand how they are applied.
Potential energy is in any object that is sationary, ie an aircraft on the crest of a hill about to roll down. The energy then becomes kinetic energy once the a/c begins to roll down the hill.
The same thing applies when an a/c is in a glide, it is basically gliding down a hill until it reaches the ground. Once it reaches the ground in in one peice, or in several, it then has potential energy once more.
There are other factors in the glide, lift weight drag and gravity, .... but these can all be desribed as kinetic energy and from the formula 1/2 M x v2 describes the amount of energy that is propelling the a/c forward. However drag will dissapate the energy as there is no thrust to maintain it. ie Thrust = Drag in straight and level, Thrust is greater then drag in climb or acceleration, thrust is less than drag in decent and while slowing down....
If im wrong ill admit it, but this is what i have read in my Bob Tait CPL aerodynamics text
Potential energy is in any object that is sationary, ie an aircraft on the crest of a hill about to roll down. The energy then becomes kinetic energy once the a/c begins to roll down the hill.
The same thing applies when an a/c is in a glide, it is basically gliding down a hill until it reaches the ground. Once it reaches the ground in in one peice, or in several, it then has potential energy once more.
There are other factors in the glide, lift weight drag and gravity, .... but these can all be desribed as kinetic energy and from the formula 1/2 M x v2 describes the amount of energy that is propelling the a/c forward. However drag will dissapate the energy as there is no thrust to maintain it. ie Thrust = Drag in straight and level, Thrust is greater then drag in climb or acceleration, thrust is less than drag in decent and while slowing down....
If im wrong ill admit it, but this is what i have read in my Bob Tait CPL aerodynamics text
4SPOOLED
WRONG. I have a very good grasp of KE and PE and how it applies in the real world. If you knew me and what I currently do you would be embarrassed by that statement.
Yep, these are all forces.
Bulls**t. They are all forces.
Please tell me where in Bob Tait’s books it says that KE is a force because this is what you have previously said. I strongly doubt it does because Bob is much smarter than to say such things in his very fine books. I will say it again, KE and PE is energy, not a force. The energy is the resultant of the force.
From Wikipedia, the free encyclopedia.
Lift, an aerodynamic force.
Weight is the interaction of matter with a gravitational field. It is equal to the mass of the object multiplied by the magnitude of the gravitational field. "Weight" is often used as a synonym for mass. The weight of a kilogram of material on Earth is called a kilogram-force. The weight force that we sense is actually the normal force exerted by the surface we stand on, which prevents us from being pulled to the centre of the Earth
Drag is the sum of all the aerodynamic or hydrodynamic forces in the direction of the external fluid/gas flow.
Thrust is a reaction force described quantitatively by Newton's Second and Third Law of physics.
Its easy to google these and get a result, but you still dont understand how they are applied.
There are other factors in the glide, lift weight drag and gravity,
.... but these can all be described as kinetic energy
If im wrong ill admit it, but this is what i have read in my Bob Tait CPL aerodynamics text
From Wikipedia, the free encyclopedia.
Lift, an aerodynamic force.
Weight is the interaction of matter with a gravitational field. It is equal to the mass of the object multiplied by the magnitude of the gravitational field. "Weight" is often used as a synonym for mass. The weight of a kilogram of material on Earth is called a kilogram-force. The weight force that we sense is actually the normal force exerted by the surface we stand on, which prevents us from being pulled to the centre of the Earth
Drag is the sum of all the aerodynamic or hydrodynamic forces in the direction of the external fluid/gas flow.
Thrust is a reaction force described quantitatively by Newton's Second and Third Law of physics.
4Spooled, maybe you're winding us up here...an object that has been sitting on top of a hill certainly does have an amount of potential energy; when it starts rolling down that potential is converted to kinetic energy, but when it comes to rest at the bottom it doesn't magically get that potential energy back again!
Imagine a frictionless rollercoaster; sitting still at the top of the track, it has no kinetic energy but a heap of potential. Given a tiny push to get going, it will accelerate down the track, converting that potential into kinetic energy.
As it goes up the next hill, it will convert kinetic back into potential, slowing down as it goes up.
In an ideal world, it would be able to just get up a hill of equal height to the start point as it came to a halt, but in the real case it won't ever make it back to the same height because of frictional losses of energy from the wheels rubbing on the track, bearings rubbing, air resistance and so on.
To clear things up, borrow a high school physics text from the library and start working through it; it'll certainly help with these concepts, particularly if you are thinking of instructing at any stage - at the moment, you're shooting from the hip, by the looks.
Imagine a frictionless rollercoaster; sitting still at the top of the track, it has no kinetic energy but a heap of potential. Given a tiny push to get going, it will accelerate down the track, converting that potential into kinetic energy.
As it goes up the next hill, it will convert kinetic back into potential, slowing down as it goes up.
In an ideal world, it would be able to just get up a hill of equal height to the start point as it came to a halt, but in the real case it won't ever make it back to the same height because of frictional losses of energy from the wheels rubbing on the track, bearings rubbing, air resistance and so on.
To clear things up, borrow a high school physics text from the library and start working through it; it'll certainly help with these concepts, particularly if you are thinking of instructing at any stage - at the moment, you're shooting from the hip, by the looks.
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if im wrong im wrong, obviously i have no place to argue with an ATPL, however i think a few of the points i made were valid.
Just a quickie though, why is it then that we need to dissapate kinetic energy in the landing roll to reduce our landing distance?
Also why is kinetic energy defined as the ability to do work, and then defined as work is done when a force moves through a certain distance, and energy is the ability to produce motion.
Wouldnt then a A/C in flight under power/glide e.t.c have energy, and wouldnt this energy be called kinetic energy?
Sorry if i have hijacked this thread from "winglets" anyway
Just a quickie though, why is it then that we need to dissapate kinetic energy in the landing roll to reduce our landing distance?
Also why is kinetic energy defined as the ability to do work, and then defined as work is done when a force moves through a certain distance, and energy is the ability to produce motion.
Wouldnt then a A/C in flight under power/glide e.t.c have energy, and wouldnt this energy be called kinetic energy?
Sorry if i have hijacked this thread from "winglets" anyway