Aerodynamics thread

[Engineer]

Re: J-20 The New Generation Fighter Thread IV

The resultant of a vector in Thrust vectoring is
Vertical: L - W + T sin(c) = Fv

One equation gives the the net vertical force Fv, and the other gives the net horizontal force Fh. If we denote the thrust by the symbol T, the lift by L, the drag by D, and the weight by W.

If you notice that is a sum of vectors, or momenta sum of vectors of the aircraft momentum.

As described by the same NASA paper that you used, thrust vectoring is a moment-producing effector. At the same time, using thrust vectoring to pitch up decreases lift. That is because the nozzle is not positioned at the aircraft's center-of-gravity. Given an aircraft is not a point, the equations above doesn't describe an aircraft. From

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:

Vectoring was intended primarily as a moment-producing effector, so vectoring the plume up would cause a noseup pitching moment. But the exhaust plume vectored up would decrease the lift coefficient in the adverse direction while increasing the pitching moment coefficient in the proverse direction.

can it? yes it can but for that aircraft have flight control system that swivel the nozzles accordingly along the aerodynamic surfaces.

Thrust vectoring increases turn rate simply becasue
Therefore to change momentum one must change the mass or velocity or both

Nope. Thrust vectoring doesn't increase turn rate, simply because thrust vectoring is a moment effector and doesn't change the aircraft's momentum.

 

[Engineer]

Re: J-20 The New Generation Fighter Thread IV

you do not understand it because you do not see it as vectors, you see lift as wing lift, not as vector, as long as you do not see it as a vector system you won`t understand.

The formula says

Vertical: L - W + T sin(c) = Fv

lift minus weight plus the product thrust sin of angle C.

that is the vertical force, and forces are vectors, plus i am just quoting what nasa says.

If you can not understand it, do not take me wrong but read a bit of Linear Algebra, otherwise you will not understand what the nasa pages says.

Actually, duncanidaho is spot on by saying your assumption that thrust vectoring produces lift is wrong. It is you who cannot understand basic physics and algebra. A

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. In other words, moment is not a force and thrust vectoring doesn't create vertical force. A scientific paper written by scientists and engineers is always going to trump what a web admin says.

Vectoring was intended primarily as a moment-producing effector, so vectoring the plume up would cause a noseup pitching moment. But the exhaust plume vectored up would decrease the lift coefficient in the adverse direction while increasing the pitching moment coefficient in the proverse direction.

 

[duncanidaho]

Re: J-20 The New Generation Fighter Thread IV

you do not understand it because you do not see it as vectors, you see lift as wing lift, not as vector, as long as you do not see it as a vector system you won`t understand.

The formula says

Vertical: L - W + T sin(c) = Fv

lift minus weight plus the product thrust sin of angle C.

that is the vertical force, and forces are vectors, plus i am just quoting what nasa says.

If you can not understand it, do not take me wrong but read a bit of Linear Algebra, otherwise you will not understand what the nasa pages says.

No, no, no.

As any physical body, the aircraft also has a center of mass. Now draw a line from the center of mass through the center point of the noozle.

If the noozle points in the same direction of line, you will have thrust in the direction of the line.

If the noozle points in your case of F-22 upward or downward, the thrust has two components:

one component in the direction of line, and you have thrust in the direction of the line. The center of mass will move forward in the direction of the line.

and

one component orthogonal to the line, and you have thrust orthogonal to the line. This orthogonal thrust creates a moment (torque) in the center of mass, but the center of mass doesn't move upward or downward.


If the vector of lift is greater than the vector of weight, then the center of mass will move in the direction of lift and vica versa.

Now can you see the difference? on the one side center of mass rotate, on the other side center of mass move.

 

[MiG-29]

Re: J-20 The New Generation Fighter Thread IV

No, no, no.

As any physical body, the aircraft also has a center of mass. Now draw a line from the center of mass through the center point of the noozle.

If the noozle points in the same direction of line, you will have thrust in the direction of the line.

If the noozle points in your case of F-22 upward or downward, the thrust has two components:

one component in the direction of line, and you have thrust in the direction of the line. The center of mass will move forward in the direction of the line.

and

one component orthogonal to the line, and you have thrust orthogonal to the line. This orthogonal thrust creates a moment (torque) in the center of mass, but the center of mass doesn't move upward or downward.


If the vector of lift is greater than the vector of weight, then the center of mass will move in the direction of lift and vica versa.

Now can you see the difference? on the one side center of mass rotate, on the other side center of mass move.

Look, i will not argue any more, the equation is not my invention, the definition of momentum is not my invention, the only thing i will suggest you, go read about linear algebra, understand how you add momentums as a vectors sum after that, understand what is vector and what is a vector sum, i am not going to spend 8 pages arguing with you, why? simple, i did not write the equation that is a posted in the vectored thrust of NASA, i did not made the links and you can go and check by your self.


Otherwise i will not get involved in an argument where people want to discredit me simply because just for the sake of discredit me.


The equation says vertical force on a thrust vectoring aircraft and they are multiplying by sin of angle c thrust and adding the product.
Read the relation of trigonometry has with vectors

 

[MiG-29]

Re: J-20 The New Generation Fighter Thread IV

Look at you. You so desperately need to put down J-20 that you invented myths to claim thrust vectoring helps an aircraft turn.

Look arguing with you is a moot point, you live in fantasy, Thrust vectoring does improve the turn radius and turn rate and momentum is a vector as physics definition, incresing momentum means increasing speed and that means increasing pitch rate, if you can not get it and by pride you will argue with me, well man i can not help it, you are not to communicate with me, you are just to argue just for the sake of argue.

So man live in your fantasy i won`t answer to a person who even having NASA pages and the F-18 page and many sources proving thrust vectoring increases turn rate.

SO since i know arguing with you is a moot point case closed with me live in your opinions.

 

[Engineer]

Re: J-20 The New Generation Fighter Thread IV

Look, i will not argue any more, the equation is not my invention, the definition of momentum is not my invention, the only thing i will suggest you, go read about linear algebra, understand how you add momentums as a vectors sum after that, understand what is vector and what is a vector sum, i am not going to spend 8 pages arguing with you, why? simple, i did not write the equation that is a posted in the vectored thrust of NASA, i did not made the links and you can go and check by your self.


Otherwise i will not get involved in an argument where people want to dsicredit me simply because just for the sake of discredit me.


The equation says vertical force on a thrust vectoring aircraft

Yet, here you are arguing with me, because you so desperately need to keep your fantasy afloat; a fantasy in which thrust vectoring some how defies physics and make an aircraft invincible. The simple reality is that the nozzle does not locate at the aircraft's center-of-gravity, hence side components of thrust generate moment and don't contribute to vertical acceleration. It is simple physics. No matter how many times you repeat the word "vectors", you aren't going to be able to replace real word physics with your non-sense pseudoscience.

 

[MiG-29]

Re: J-20 The New Generation Fighter Thread IV

Yet, here you are arguing with me, because you so desperately need to keep your fantasy afloat; a fantasy in which thrust vectoring some how defies physics and make an aircraft invincible. The simple reality is that the nozzle does not locate at the aircraft's center-of-gravity, hence side components of thrust generate moment and don't contribute to vertical acceleration. It is simple physics. No matter how many times you repeat the word "vectors", you aren't going to be able to replace real word physics with your non-sense pseudoscience.

Vertical: L - W + T sin(c) = Fv

lift minus weight plus the product thrust sin of angle C.

Force Vertical=Fv


Sin of angle of C


Better go and read why you are multiplying sin of angle C with Thrust


When you realize the relation of a vectors sum has with hypotenuse and the resultant and why the equation says vertical force then we argue.

The equation is adding lift to thrust to get a vertical component

Go and read trigonometry do not waste time.

 

[Engineer]

Re: J-20 The New Generation Fighter Thread IV

Look arguing with you is a moot point, you live in fantasy, Thrust vectoring does improve the turn radius and turn rate and momentum is a vector as physics definition, incresing momentum means increasing speed and that means increasing pitch rate, if you can not get it and by pride you will argue with me, well man i can not help it, you are not to communicate with me, you are just to argue just for the sake of argue.

Wrong, and your pseudoscience explanation is complete garbage. Here is why: momentum is related to straight line motion, whereas pitch-rate is a rotational motion. Change to momentum does nothing to improve pitch rate, and change in pitch rate does nothing to momentum. As far as thrust vectoring is concerned, it is a moment-producing effector and doesn't generate vertical acceleration to aid an aircraft during a turn.

Your psychoanalysis is also complete garbage. I am not here to argue with you. Rather, what I am doing is point out your bullshit for other forum members, because I know I am right and you are wrong. If you actually think I am trying to convince you of something, then you are obviously over estimating your importance.

So man live in your fantasy i won`t answer to a person who even having NASA pages and the F-18 page and many sources proving thrust vectoring increases turn rate.

SO since i know arguing with you is a moot point case closed with me live in your opinions.

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that says thrust vectoring produces moment, and that lift coefficient decreases during pitch up. I am simply saying what NASA is saying, and what NASA says is contrary to your claim.

Vectoring was intended primarily as a moment-producing effector, so vectoring the plume up would cause a noseup pitching moment. But the exhaust plume vectored up would decrease the lift coefficient in the adverse direction while increasing the pitching moment coefficient in the proverse direction.

Then we have

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. Your imagination, in which an aircraft employs TVC to out turn its opponent and become king of the sky, doesn't happen in real life. What happened in real word exercises are contrary to your claim, and that tells us those TVC did not help the aircraft in turning.

There are also sources

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, explicitly stating TVC doesn't decrease turn radius:

At these speeds, TVC-equipped aircraft (lower one in animation) actually turns at same rate as non-TVC aircraft; however, TVC increases angle between aircraft and air flow around it (Angle of Attack, abbreviated AoA), resulting in increase in drag for no decrease in diameter of turn (that is, maneuverability), resulting in increased energy loss during maneuvers, leaving aircraft more and more vulnerable to missiles and gunfire as fight drags on. In short, aircraft does not fly in direction its nose is pointing at.

The only consented advantage to TVC is post-stall capability, which is actually useless in a dogfight.

Another danger happens at turn onset - when TVC engages, aircraft using it rotates in air, rear end of aircraft drops, and aircraft itself sinks in air, resulting in huge energy loss, which can be exploited by skillfull pilot. Post-stall maneuvers - one of main "benefits" of thrust vectoring - are useless for exactly that reason.

 

[Engineer]

Re: J-20 The New Generation Fighter Thread IV

Vertical: L - W + T sin(c) = Fv

lift minus weight plus the product thrust sin of angle C.

Force Vertical=Fv


Sin of angle of C


Better go and read why you are multiplying sin of angle C with Thrust


When you realize the relation of a vectors sum has with hypotenuse and the resultant and why the equation says vertical force then we argue.

The equation is adding lift to thrust to get a vertical component

Go and read trigonometry do not waste time.

Since the equations assume the aircraft as a point, they do not capture the real dynamics found on an aircraft. So, your above arguments based on the above equations are irrelevant.

The fact that the nozzle does not locate at the center-of-gravity of the aircraft means any side component of thrust will create moment. No vertical force is created as a result because the aircraft is free to rotate. It is because of this that thrust vectoring is called a moment-producing effector. From

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:

Vectoring was intended primarily as a moment-producing effector, so vectoring the plume up would cause a noseup pitching moment. But the exhaust plume vectored up would decrease the lift coefficient in the adverse direction while increasing the pitching moment coefficient in the proverse direction.

 

[Air Force Brat]

Re: J-20 The New Generation Fighter Thread IV

Wrong, and your pseudoscience explanation is complete garbage. Here is why: momentum is related to straight line motion, whereas pitch-rate is a rotational motion. Change to momentum does nothing to improve pitch rate, and change in pitch rate does nothing to momentum. As far as thrust vectoring is concerned, it is a moment-producing effector and doesn't generate vertical acceleration to aid an aircraft during a turn.

Your psychoanalysis is also complete garbage. I am not here to argue with you. Rather, what I am doing is point out your bullshit for other forum members, because I know I am right and you are wrong. If you actually think I am trying to convince you of something, then you are obviously over estimating your importance.

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that says thrust vectoring produces moment, and that lift coefficient decreases during pitch up. I am simply saying what NASA is saying, and what NASA says is contrary to your claim.


Then we have

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. Your imagination, in which an aircraft employs TVC to out turn its opponent and become king of the sky, doesn't happen in real life. What happened in real word exercises are contrary to your claim, and that tells us those TVC did not help the aircraft in turning.

There are also sources

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, explicitly stating TVC doesn't decrease turn radius:

The only consented advantage to TVC is post-stall capability, which is actually useless in a dogfight.

1Come on eng, that vid is bogus and you know it, a Flanker with OVT, has a higher turn RATE, than a Flanker without OVT, and the Eagle driver is illustrating their one kill on a Raptor, and the unfortunate IAFs inability to fight their aircraft, but they did learn and were a lot tougher on the second go around, which is why Red Flag works.
2 You're little automation actually proves that OVT does work as your two little aircraft near the edge of the page, the OVT aircraft has a perfect lead on the non-OVT bird and is positioned perfectly for a gun shot or missle shot, nice work ace! Brat