Aerodynamics thread

[MiG-29]

Re: J-20 The New Generation Fighter Thread IV

so you still pretend jet fighter is a point, and all forces are exerted to this point. that is what i call a simple lack of understanding. .

Look a good advice, study trigonometry, otherwise your opinions are just a waste of time to me to answer to a person who makes mental explanations without a shred of what is a vector resultant and why the formula uses trigonometry, otherwise you can live in your fantasy and come up to me like i am wrong to defend you lack of knowledge of basic principles of trogonometry and vectorial Algebra.

Live in your fantasy if you wish, but the formula says vertical force component of Thrust vectoring, otherwise go to the NASA webpage and complaign

 

[MiG-29]

Re: J-20 The New Generation Fighter Thread IV

If you aim the thrust of an aircraft in the direction shown in the image, it will head into a nosedive. How that helps your "TVC produces lift" argument escapes me.

do you understand the values sine can get?

well study trigonometry and you will understand the formula otherwise this type of explanation you give is of kinder garden

But i know most important for you is pride and not even admit the thrust is multiplied by sine of the thrust vector angle and added up to lift

 

[Air Force Brat]

Re: J-20 The New Generation Fighter Thread IV

If you aim the thrust of an aircraft in the direction shown in the image, it will head into a nosedive. How that helps your "TVC produces lift" argument escapes me.

Now Jed, that is absurd, and guys all this picking on Mig 29, sounds like Jr. High School girls, OVT is a Fantastic asset to the F-22 and the T-50, its my very honest and humble opinion that Dr. Song would like to have incorporated it on the J-20, and Jed that observation is only accurate in the sense that yes deflecting the thrust down, will pitch the nose down, as does moving the stick forward with canards or horizontal stabs and elevators, and to be perfectly frank an F-22 doesn't care if its pointed straight up or straight down, I would imagine that the J-20 hopes to achieve that same tractability. Mig has made it clear that he also likes the J-20 as do I, its a gorgeous smart aeroplane. For any of you bright gentlemen to contend that OVT is not an agility enhancer is simply dishonest. All this talk of moments and vectors and thrust and drag is talk until you observe the actual aircraft and its real performance, and yes real engineers are surprised by test aircraft for more often than they care to admit, and every test flight in a new aircraft might be your last? So how about we lighten up this conversation and stick to aerodynamics and leave the personal attacks, they are demeaning to you, and you are all better than that, it would be a shame if bd or siege, or tp has to babysit on the aerodynamics thread. This kind of junk in this thread may be keeping some of our members from joining what should be the most interesting thread on Sino Defense? BRAT

 

[Engineer]

Re: J-20 The New Generation Fighter Thread IV

Look a good advice, study trigonometry, otherwise your opinions are just a waste of time to me to answer to a person who makes mental explanations without a shred of what is a vector resultant and why the formula uses trigonometry, otherwise you can live in your fantasy and come up to me like i am wrong to defend you lack of knowledge of basic principles of trogonometry and vectorial Algebra.

It is not "like" you are wrong. You are wrong. It is simple as that. The true reason you are going off tangent with vectors and trigonometry is that you are unable to prove your claims. Those of us who understand physics and linear algebra do not need to rely on technical jargon as you do. All we need is one single statement, and that is "moment does not equate to force". Indeed, you are still unable to prove how we are wrong.

Live in your fantasy if you wish, but the formula says vertical force component of Thrust vectoring, otherwise go to the NASA webpage and complaign

The formulas describe forces on a point, not forces on an actual aircraft. The nozzle being at a different location to the aircraft's center-of-gravity means thrust vectoring produces moment. Moment is not force, so generation of pitching moment by thrust vectoring does not equate to generation of lift. That's just simple Laws of Physics.

 

[Engineer]

Re: J-20 The New Generation Fighter Thread IV

do you understand the values sine can get?

well study trigonometry and you will understand the formula otherwise this type of explanation you give is of kinder garden

But i know most important for your is pride and not even admit the thrust is multiplied by sine of the thrust vector angle and added up to lift

Position of the nozzle and the aircraft's center-of-gravity do not coincide. Hence with thrust multiplied by sine of thrust vector angle, you get side components of thrust that produce moment. Moment causes the aircraft to spin and does not create the vertical force component called lift.

 

[MiG-29]

Re: J-20 The New Generation Fighter Thread IV

Now Jed, that is absurd, and guys all this picking on Mig 29, sounds like Jr. High School girls, OVT is a Fantastic asset to the F-22 and the T-50, its my very honest and humble opinion that Dr. Song would like to have incorporated it on the J-20, and Jed that observation is only accurate in the sense that yes deflecting the thrust down, will pitch the nose down, as does moving the stick forward with canards or horizontal stabs and elevators, and to be perfectly frank an F-22 doesn't care if its pointed straight up or straight down,

Air force brat

If you have read what the NASA webpage says

Forces are vector quantities having a magnitude and a direction. The resulting acceleration, velocity and displacement of the aircraft are also vector quantities which can be determined by Newton's second law of motion and the rules of vector algebra. There are two component equations for the force on an aircraft. 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, the usual force equations for an aircraft in level flight are


Source

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You will see they give you a net vertical force, regardless of the math which is very simple, is basicly trigonometry applied to a Vector.


Here you will have people say that is not true.

Why simple most people here did not visualize is thrust vectoring as the word imply Vectoring=vector as a resultant.
So most people do not consider angles and thrust projections based upon trigonometry.
I understand some might not see it simply because of lack of knowledge about vectors or they forgot the basic trigonometry they studied at high school.

I understand no one knows everything, and all we have to learn from others.
However most of what they say is based upon bias, and pure pride to do not admit they are wrong

The fact is Thrust vectoring improves agility, turn rates, roll rates, post stall, stealth ect ect..

If you watch this video, this video sumarizes all what we have spoken here.

Thrust vectoring allowed to X-31 beat an F-18, 129 times out of 130, it means it only lost once.
They mention stealth is improved by thrust vectoring and also mention Cobra might not be very useful in combat where you have a several fighters in combat, they also mention is debatable the utility of Cobra.
Thrust vectoring is useful, however i admit with HMS and highly offbored missiles the advantage of Thrust vectoring reduces and the useage of Cobra in some situations might be counterproductive.
However consider post stall is more than just Cobra, F-22 can figh as well as a Eurofighter without HMS and highly offbored missiles and Russia`s Su-35`s and T-50 do have HMS and highly offbored missiles.

F-22 also will include soon the AIM-9X and in the future HMS.


[video=youtube;nF-aBeuTphc]https://www.youtube.com/watch?v=nF-aBeuTphc[/video]

 

[Engineer]

Re: J-20 The New Generation Fighter Thread IV

Now Jed, that is absurd, and guys all this picking on Mig 29, sounds like Jr. High School girls, OVT is a Fantastic asset to the F-22 and the T-50, its my very honest and humble opinion that Dr. Song would like to have incorporated it on the J-20, and Jed that observation is only accurate in the sense that yes deflecting the thrust down, will pitch the nose down, as does moving the stick forward with canards or horizontal stabs and elevators, and to be perfectly frank an F-22 doesn't care if its pointed straight up or straight down, I would imagine that the J-20 hopes to achieve that same tractability. Mig has made it clear that he also likes the J-20 as do I, its a gorgeous smart aeroplane. For any of you bright gentlemen to contend that OVT is not an agility enhancer is simply dishonest. All this talk of moments and vectors and thrust and drag is talk until you observe the actual aircraft and its real performance, and yes real engineers are surprised by test aircraft for more often than they care to admit, and every test flight in a new aircraft might be your last? So how about we lighten up this conversation and stick to aerodynamics and leave the personal attacks, they are demeaning to you, and you are all better than that, it would be a shame if bd or siege, or tp has to babysit on the aerodynamics thread. This kind of junk in this thread may be keeping some of our members from joining what should be the most interesting thread on Sino Defense? BRAT

Yes, when thrust deflects down, the nose will go down. You are also right that it is the same result as stick forward with canard or a tailplane. Those are simply the result of

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. Indeed, thrust vectoring only produces moment and that's all there is to it.

MiG-29 will you tell you that thrust vectoring produces vertical component. However, it is merely a myth he wants to believe in and wants the rest of us to believe in. He has absolutely no concern about real world physics, and that's why he is taking so much flak from the rest of us.

Imagine holding up an aircraft model with a finger. By placing your finger underneath the model's center-of-gravity, the aircraft stays on your finger and is perfectly balanced. In essence, your finger is providing lift for the model. If you place your finger at the nozzle instead, the model would simply fall off and shatter on the ground. That is because the finger acts on the end of a lever, providing moment but not lift. That is exactly what a thrust vectoring does and here are some diagrams to illustrate.

MiG-29 thinks his formulas prove that thrust vectoring provides lift. However, the reality is that the formulas simply assume your finger is conveniently located underneath the model's center-of-gravity. So, while the formulas are applicable on the

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, they are completely irrelevant when it comes to a fighter aircraft. At the end of the day, TVN still doesn't generate lift to help the aircraft turns. MiG-29's myth remains a myth.

As for being agility enhancer, thrust vectoring does allow an aircraft to maneuver regardless of airspeed. This allows the aircraft to be in a controllable tumble while aircraft without thrust vectoring cannot. That is called post-stall maneuverability, and is unrelated to an aircraft in a level turn.

 

[Engineer]

Re: J-20 The New Generation Fighter Thread IV

Air force brat

If you have read what the NASA webpage says

Forces are vector quantities having a magnitude and a direction. The resulting acceleration, velocity and displacement of the aircraft are also vector quantities which can be determined by Newton's second law of motion and the rules of vector algebra. There are two component equations for the force on an aircraft. 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, the usual force equations for an aircraft in level flight are


Source

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You will see they give you a net vertical force, regardless of the math which is very simple, is basicly trigonometry applied to a Vector.


Here you will have people say that is not true.

Why simple most people here did not visualize is thrust vectoring as the word imply Vectoring=vector as a resultant.
So most people do not consider angles and thrust projections based upon trigonometry.
I understand some might not see it simply because of lack of knowledge about vectors or they forgot the basic trigonometry they studied at high school.

I understand no one knows everything, and all we have to learn from others.
However most of what they say is based upon bias, and pure pride to do not admit they are wrong

An aircraft's nozzle does not locate at the aircraft's center-of-gravity. Hence, thrust vectoring generates moment and not lift. Your arguments are irrelevant.

The fact is Thrust vectoring improves agility, turn rates, roll rates, post stall, stealth ect ect..

If you watch this video, this video sumarizes all what we have spoken here.

Thrust vectoring allowed to X-31 beat an F-18, 129 times out of 130, it means it only lost once.
They mention stealth is improved by thrust vectoring and also mention Cobra might not be very useful in combat where you have a several fighters in combat, they also mention is debatable the utility of Cobra.
Thrust vectoring is useful, however i admit with HMS and highly offbored missiles the advantage of Thrust vectoring reduces and the useage of Cobra in some situations might be counterproductive.
However consider post stall is more than just Cobra, F-22 can figh as well as a Eurofighter without HMS and highly offbored missiles and Russia`s Su-35`s and T-50 do have HMS and highly offbored missiles.

F-22 also will include soon the AIM-9X and in the future HMS.

Here is a video showing thrust vectoring does not help an aircraft turn.

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. The video explains how pilots on Su-30MKI thought they could get faster turn with TVC. However, the Su-30MKI stalled, quickly lost energy and lost the engagement. Same situation happened with the F-22.
[video=youtube;M-CRINeb9_A]http://www.youtube.com/watch?v=M-CRINeb9_A&feature=player_detailpage#t=458s[/video]

Here is a transcript of the part of interest:

The F22 can sustain a turn rate of 28 deg per second at 20,000 feet while the F-15 can get an instantaneous rate of 21 and a sustained rate of 15-16 degrees. So you are pulling and hoping. Post stall, maneuver, the ass end drops and instead of going up, it just drops in mid air and the airplane will rotate with its nose up. This is where the Eagle or Viper pilot would pull up vertical, switch to guns, then come down and take a shot at the F-22. Of course you have to first get in close to do this, most probably the F-22 will kill you before that.

The Su-30? No problem. Big airplane. Big cross section. Jamming to get to the merge, so you have to fight close... he has 22 - 23 degrees per second sustained turn rate. We've been fighting the Raptor, so we've been going oh dude, this is easy. So as we're fighting him, all of a sudden you'd see the ass end kick down, going post stall - but now he starts falling from the sky. The F-15 wouldn't even have to pull up. slight pull up on the stick, engage guns, come down and drill his brains out.

Real word exercises that contradict your myths.

 

[ahadicow]

Re: J-20 The New Generation Fighter Thread IV

Now Jed, that is absurd, and guys all this picking on Mig 29, sounds like Jr. High School girls, OVT is a Fantastic asset to the F-22 and the T-50, its my very honest and humble opinion that Dr. Song would like to have incorporated it on the J-20, and Jed that observation is only accurate in the sense that yes deflecting the thrust down, will pitch the nose down, as does moving the stick forward with canards or horizontal stabs and elevators, and to be perfectly frank an F-22 doesn't care if its pointed straight up or straight down, I would imagine that the J-20 hopes to achieve that same tractability. Mig has made it clear that he also likes the J-20 as do I, its a gorgeous smart aeroplane. For any of you bright gentlemen to contend that OVT is not an agility enhancer is simply dishonest. All this talk of moments and vectors and thrust and drag is talk until you observe the actual aircraft and its real performance, and yes real engineers are surprised by test aircraft for more often than they care to admit, and every test flight in a new aircraft might be your last? So how about we lighten up this conversation and stick to aerodynamics and leave the personal attacks, they are demeaning to you, and you are all better than that, it would be a shame if bd or siege, or tp has to babysit on the aerodynamics thread. This kind of junk in this thread may be keeping some of our members from joining what should be the most interesting thread on Sino Defense? BRAT

No, we're not picking on Mig 29, nor are we disputing the flight proformance of F-22 and the T-50. We're stating a simple physical fact: the TVC do not affect a jet plane maximum sustained turn rate or its sustained turing radius. we have laiden out our evidence and reason. If you do not agree with us, that's fine, but don't point an accusing finger at people just because they want to tell the truth.

 

[MiG-29]

Re: J-20 The New Generation Fighter Thread IV

No, we're not picking on Mig 29, nor are we disputing the flight proformance of F-22 and the T-50. We're stating a simple physical fact: the TVC do not affect a jet plane maximum sustained turn rate or its sustained turing radius. we have laiden out our evidence and reason. If you do not agree with us, that's fine, but don't point an accusing finger at people just because they want to tell the truth.

Look you do not pick on me, you simply show how much you want to scape from reality

Fig. 3.- Increased Sustained Turn Rate with TVNs
the source proves how much you deny things even having evidence by studies by NATO and ITP

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However you do not even understand why the formula uses W-L+T sin(c)=Fv to get the vertical force.

I will simplify it for you

Torque is a vector, in fact is called cross product, if you know that you will understand the whole thrust vectoring issue as a vector system.

The cross product, also called the vector product, is an operation on two vectors.
source

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Torque is defined as

= r x F = r F sin().

In other words, torque is the cross product between the distance vector (the distance from the pivot point to the point where force is applied) and the force vector, 'a' being the angle between r and F.

source

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The aircraft is pitching up as the product of the thrust projection on the aircraft and the cross product of the center of gravity.

The resultant can be expressed as the vertical element affecting lift


What does it mean? simple the resultant increases the picth momentum and this is translated into higher sustained turn rate.

Good advice my friend read linear algebra.