Aerodynamics thread

[MiG-29]

Re: J-20 The New Generation Fighter Thread IV

Once again, your lies are exposed.



The simple fact is that thrust vectoring does not increase lift, thus does not increase turn rate.

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:


Ignoring it isn't going to make it go away.

Let me do like you do No no no hahahaha another paper that proves how much you deny reality.


For instance, consider an aircraft that has an excellent
turn rate at a given speed. Another aircraft, on account of,
say, an inferior T/W, may not be able to achieve such high
rates. However, it may have excellent abilities to point
quickly, perhaps through Post Stall Maneuverability
(PSM) and Thrust Vectoring (TV). In combat, where
aircraft turn into each other and seek firing positions by
pointing at the adversary, the second aircraft may actuallyhave a greater chance of winning, although it may not turn
as quickly as the first aircraft. This suggests that a superior
performance rating in terms of traditional metrics does not
immediately translate into combat superiority, which has
to be evaluated using agility...................
Thrust VectoringHerbst [3] has pointed out the importance of PSM for
enhanced combat capability. Costes [17], Gal-or [18],
Anderson [19], and Tamrat [4, 20] have shown that TV
and PSM improve the chances of victory in a head-to-head
combat by improving the agility of the aircraft. It is of
interest to know how PSM and TV, together or separately,
help to do so.
Three F-18 configurations were tested by them using
the above metric: standard (no TV, AOA for ITR of 20
deg, and maximum AOA of 30 deg), advanced (TV, AOA
for maximum ITR of 20 deg, and maximum AOA of 70
deg), and super-advanced (TV, AOA for maximum ITRof 35 deg,
maximum AOA of 70 deg). It may be noted that
stall AOA for F-18 is around 35 deg. The metric was
evaluated for a variety of initial Mach number and altitude
combinations. As expected, the advanced aircraft showed
better agility as compared to the standard configuration.
The time to complete the maneuver was lesser for the
advanced aircraft, especially at higher initial altitudes,
which constitutes a significant advantage. The turn diameter
was smaller and the turn rate was higher as well


ITR = Instantaneous Turn Rate

source

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another source

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Under the same conditions, but in a sustained turn, where the pitch element of the control surface deflection was 6° up, this could be reduced to 2° combined with a 4° nozzle-up component. In this configuration lift coefficient would be increased by 14%, translating into a 9% improvement in turn rate. Take-off distance could be cut by at least 25%.

source

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Of course you will deny it

 

[Engineer]

Re: J-20 The New Generation Fighter Thread IV

Let me do like you do No no no hahahaha another paper that proves how much you deny reality.

LMAO! That is indeed how you act when you are presented with the reality, where TVC-equipped aircraft turns at same rate as non-TVC aircraft:

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.

 

[Engineer]

Re: J-20 The New Generation Fighter Thread IV

For instance, consider an aircraft that has an excellent turn rate at a given speed. Another aircraft, on account of, say, an inferior T/W, may not be able to achieve such high rates. However, it may have excellent abilities to point quickly, perhaps through Post Stall Maneuverability (PSM) and Thrust Vectoring (TV). In combat, where aircraft turn into each other and seek firing positions by pointing at the adversary, the second aircraft may actuallyhave a greater chance of winning, although it may not turn as quickly as the first aircraft. This suggests that a superior performance rating in terms of traditional metrics does not immediately translate into combat superiority, which has to be evaluated using agility...................
Thrust VectoringHerbst [3] has pointed out the importance of PSM for enhanced combat capability. Costes [17], Gal-or [18], Anderson [19], and Tamrat [4, 20] have shown that TV and PSM improve the chances of victory in a head-to-head combat by improving the agility of the aircraft. It is of interest to know how PSM and TV, together or separately, help to do so.

Post-stall maneuverability is related to nose-pointing ability, not to performance in a level turn. While post-stall maneuver is a widely acknowledge capability of thrust-vectoring, the capability is also practically useless in a dog fight since the aircraft would lose speed quickly thus become an easy kill. This has already been demonstrated in

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. From that very same paper you quoted from:

Longer periods of PSM may lead to greater energy losses, which is detrimental to the performance of the aircraft.

Three F-18 configurations were tested by them using the above metric: standard (no TV, AOA for ITR of 20 deg, and maximum AOA of 30 deg), advanced (TV, AOA for maximum ITR of 20 deg, and maximum AOA of 70 deg), and super-advanced (TV, AOA for maximum ITRof 35 deg, maximum AOA of 70 deg). It may be noted that stall AOA for F-18 is around 35 deg. The metric was evaluated for a variety of initial Mach number and altitude combinations. As expected, the advanced aircraft showed better agility as compared to the standard configuration. The time to complete the maneuver was lesser for the advanced aircraft, especially at higher initial altitudes, which constitutes a significant advantage. The turn diameter was smaller and the turn rate was higher as well


ITR = Instantaneous Turn Rate

source

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another source

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Due to your lack of understanding, you left out an important piece of detail from those articles. That detail is the origin of the equation of motions. In the opening sentence of the paragraph which you have quoted is this:

Kutschera and Render[12] developed a new metric which is primarily a maneuverability metric, as per the definition given in Section 2.

Kutschera's entire PhD thesis is about his new agility metric, in which he used an F-18 to illustrate his arguments. However, that F-18 model has a great flaw as it assumed the F-18 as a point mass as

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illustrates:

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The same point mass assumption is employed whenever there is an analysis on TVC. In turn, all of these equations are derived from

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. The equations glanced over the concept of thrust deflection angle, but then set the angle to zero. The assumption of an aircraft being a point mass works when deflection angle is zero, but doesn't work when there is a non-zero deflection angle.

Now, an aircraft is not a point. An aircraft nozzle is not situated at the aircraft's center-of-gravity, but at the tail-end of the aircraft. As such, side component of thrust from vectoring generates a moment. Moment is not a force, thus thrust vectoring does not generate a vertical force know as aerodynamics lift. You are still unable to disprove this. Using equations of motion for a point mass isn't going to disprove what I have said either.

Under the same conditions, but in a sustained turn, where the pitch element of the control surface deflection was 6° up, this could be reduced to 2° combined with a 4° nozzle-up component. In this configuration lift coefficient would be increased by 14%, translating into a 9% improvement in turn rate. Take-off distance could be cut by at least 25%.

source

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Of course you will deny it

We have already went over this particular source. The article from Flightglobal is an extract from that

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which you have posted earlier. There is sign of lack of confidence in the validity of those claims, given there is no Eurofighter operator who would purchase the TVN. Mean while,

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with a counter claim:

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.

 

[AlienCraft]

Re: J-20 The New Generation Fighter Thread IV

LMAO! That is indeed how you act when you are presented with the reality, where TVC-equipped aircraft turns at same rate as non-TVC aircraft:

if the tvc thrust direction right cross througth the roll axis with no offset distane from the roll axis. there is no trun rate contribution. but the turn rate can be affected by TVC if the TVC distributes the thrust around the roll axis with some radius.
For instance, two engines each has its own tvc that generates thrust around the roll axis both in counter clock wise direction.
it will increase the turn rate when the airplane rolls in ccw direction.

 

[Engineer]

Re: J-20 The New Generation Fighter Thread IV

if the tvc thrust direction right cross througth the roll axis with no offset distane from the roll axis. there is no trun rate contribution. but the turn rate can be affected by TVC if the TVC distributes the thrust around the roll axis with some radius.
For instance, two engines each has its own tvc that generates thrust around the roll axis both in counter clock wise direction.
it will increase the turn rate when the airplane rolls in ccw direction.

Hi!

Indeed, with one thrust vector deflected up and another deflected down, the aircraft will roll about its axis. However, this is known as a roll, not a turn, because the aircraft continues on its original flight path. Here is a video to illustrate:
[video=youtube;_HX8qAcKiBA]http://www.youtube.com/watch?v=_HX8qAcKiBA[/video]

Here is an illustration which includes roll. The rotation about the roll axis is known as a roll rate, which is what you are referring to:

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This is a turn. It is achieved through lift, not a roll.

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[ahadicow]

Re: J-20 The New Generation Fighter Thread IV

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.
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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.

SO arrogent, perfectly befitting a person engaged in imaginary physics.

increases the picth momentum and this is translated into higher sustained turn rate.

where did you get this at all.

Good advice my buddy, go attend junior high school physics class.

 

[Air Force Brat]

Re: J-20 The New Generation Fighter Thread IV

Hi!

Indeed, with one thrust vector deflected up and another deflected down, the aircraft will roll about its axis. However, this is known as a roll, not a turn, because the aircraft continues on its original flight path. Here is a video to illustrate:
[video=youtube;_HX8qAcKiBA]http://www.youtube.com/watch?v=_HX8qAcKiBA[/video]

Here is an illustration which includes roll. The rotation about the roll axis is known as a roll rate, which is what you are referring to:

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This is a turn. It is achieved through lift, not a roll.

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However Eng, if you were a pilot, you would know you always "roll into a turn" and that you "climb around the turn", this would be a much more fruitfull thread if instead of arguing, and I enjoy a good on point "meetin of the minds", you would put aside your anti OVT prejudice.

This continual denial of the real world benefits of OVT, is the greatest threat to your overall reputation as the "engineer", its China centric, which I have no problem with as I am US centric, but it also is intellectually dishonest. I am proud to be one of your adherants, your ability to explain the canard of the J-20 and its difference from that of the J-10 mad me a fan, and no I don't need to have you say the F-22s OVT sets it in another class, I already know that. Your little fighter turning diagram shows right well how OVT sets the stage for a gun shot or missle shot, it also shows the "overrotation of the aircraft which will cause a huge increase in drag, but once he makes the shot, he applies depitches the aircraft and "leaves". Thats why they call it "launch and leave", OVT must be used judiciously, but it does enhance the oveall manueverabilty and agility of the host aircraft, and as your little illustration so aptly demonstrates, it will give you an edge, once you have launched, you disengage and "vacate the area", its ability to "depitch" the aircraft, and exit the engagement is an equally valuable asset.

Now, would I take Russian engines and OVT on my aircraft, knowing that OVT will reduce thrust, increase maintenance/reduce engine life/ increase fuel consumption, then I would have to scratch my head and say Huummh? Brat

 

[Engineer]

Re: J-20 The New Generation Fighter Thread IV

However Eng, if you were a pilot, you would know you always "roll into a turn" and that you "climb around the turn", this would be a much more fruitfull thread if instead of arguing, and I enjoy a good on point "meetin of the minds", you would put aside your anti OVT prejudice.

This continual denial of the real world benefits of OVT, is the greatest threat to your overall reputation as the "engineer", its China centric, which I have no problem with as I am US centric, but it also is intellectually dishonest. I am proud to be one of your adherants, your ability to explain the canard of the J-20 and its difference from that of the J-10 mad me a fan, and no I don't need to have you say the F-22s OVT sets it in another class, I already know that. Your little fighter turning diagram shows right well how OVT sets the stage for a gun shot or missle shot, it also shows the "overrotation of the aircraft which will cause a huge increase in drag, but once he makes the shot, he applies depitches the aircraft and "leaves". Thats why they call it "launch and leave", OVT must be used judiciously, but it does enhance the oveall manueverabilty and agility of the host aircraft, and as your little illustration so aptly demonstrates, it will give you an edge, once you have launched, you disengage and "vacate the area", its ability to "depitch" the aircraft, and exit the engagement is an equally valuable asset.

Now, would I take Russian engines and OVT on my aircraft, knowing that OVT will reduce thrust, increase maintenance/reduce engine life/ increase fuel consumption, then I would have to scratch my head and say Huummh? Brat

I have no prejudice against thrust vectoring, just as I have no prejudice against an aileron, an elevator or a rudder. All I have been saying is that thrust vectoring does not produce lift that turns an aircraft. Certain someone has problem accepting that, as the fact I have presented contradict his imagination of how thrust vectoring should work. So far, that statement of mine has stood up to scrutiny and yet to be dis-proven.

 

[MiG-29]

Re: J-20 The New Generation Fighter Thread IV

I have no prejudice against thrust vectoring, just as I have no prejudice against an aileron, an elevator or a rudder. All I have been saying is that thrust vectoring does not produce lift that turns an aircraft. Certain someone has problem accepting that, as the fact I have presented contradict his imagination of how thrust vectoring should work. So far, that statement of mine has stood up to scrutiny and yet to be dis-proven.

hahah pure fantasies and pride i will show you where you have no idea of how an aircraft turns

Maneuverability
Thrust vectoring can greatly improve the maneuverability of an aircraft such as
turning, useful in combat to out maneuver non thrust vector controlled enemy
aircraft.
later let us go to the math

For turning with vectored thrust, the equation from figure 8 is:
n*W = L + T*sin(a + fT) (11)
Where the load factor n = (T*sin(a + fT) / W) / (L/D) (12)
(Raymer, 2006)
By maximizing the load factor, the turning rate is maximized, so by differentiating
equation 12 with respect to thrust angle, and maximizing this equation provides
the thrust angle for maximum turn rate, which turns out to be 90º. In other words,
when the thrust angle is perpendicular to flight direction, maximum turn rate is
achieved

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but let me imagine your reaction No no no wrong hahahahah, moment is not a vector, no vectors have no direction and magnitude, pitch is a sewsaw hahahaha Typical reation No no no, thrust vectoring does not improve turn rate, its the canards of the Eurofighter ITP is just a brochure no no no they are not engineers like me, ITP is not owned 50% by Rolls Royce no no wrong, irrelevant wrong


hahaha no i do not know what is cross product of vectors but torque is no a vector no no no wrong and later it is mine quoting verbosity hahaha pure excuses to hide you can not admit a mistake

 

[MiG-29]

Re: J-20 The New Generation Fighter Thread IV

However Eng, if you were a pilot, you would know you always "roll into a turn" and that you "climb around the turn", this would be a much more fruitfull thread if instead of arguing, and I enjoy a good on point "meetin of the minds", you would put aside your anti OVT prejudice.

This continual denial of the real world benefits of OVT, is the greatest threat to your overall reputation as the "engineer", its China centric, which I have no problem with as I am US centric, but it also is intellectually dishonest. I am proud to be one of your adherants, your ability to explain the canard of the J-20 and its difference from that of the J-10 mad me a fan, and no I don't need to have you say the F-22s OVT sets it in another class, I already know that. Your little fighter turning diagram shows right well how OVT sets the stage for a gun shot or missle shot, it also shows the "overrotation of the aircraft which will cause a huge increase in drag, but once he makes the shot, he applies depitches the aircraft and "leaves". Thats why they call it "launch and leave", OVT must be used judiciously, but it does enhance the oveall manueverabilty and agility of the host aircraft, and as your little illustration so aptly demonstrates, it will give you an edge, once you have launched, you disengage and "vacate the area", its ability to "depitch" the aircraft, and exit the engagement is an equally valuable asset.

Now, would I take Russian engines and OVT on my aircraft, knowing that OVT will reduce thrust, increase maintenance/reduce engine life/ increase fuel consumption, then I would have to scratch my head and say Huummh? Brat

The problem of Post stall is a multi aircraft combat, if you apply the cobra you can kill one enemy, but a second wingman can kill the fighter doing post stall due to the speed it has lost, however since F-22 increases turn rate, the F-22 can apply stealth compromises in an easier way and still combat turning without using post stall.

F-22 pilost know the F-22 needs TVC nozzles to increase turning and rolling ability and increasing stealth.
But with HMS and highly offbored missiles and a wingman a Eurofighter can complicate things for a F-22 armed with AIM-9M and no HMS.

So F-22 pilots are asking for AIM-9Xs and HMS, but Su-35 has HMS and T-50 has HMS