Aerodynamics thread

[F-15]

The question is, does LEVCON provide superior performance in comparison to canard? You do not have experimental data to give an affirmative answer, it is that simple.

They provide pitch control, the best fighter is not because it has canards or LEVCONS but the one that has the best combination and the best tactics, any way in the PAKFA video the Sukhoi engineers say LEVCONS have their advantages over canards

 

[F-15]

The paper says that LEVCON increases sustained turn rate, which the paper explicitly links to lift enhancement. The rest of your statement about how LEVCON can cause change in pitch moment like canard can is entirely your own creation.


.

look better understand what is lift enhancement and turn rate

 

[Engineer]

Yeah you have data it is called LCA and PAKFA

PAKFA needs thrust-vectoring on top of tailplane for pitch control, which is not a sign of LEVCON providing good pitch-authority. The LCA is just too small for anything. Neither helps your arguments.

 

[Engineer]

look better understand what is lift enhancement and turn rate

Turn rate is not the same as pitch moment! No one is disputing that LEVCON does enhance lift, but LEVCON clearly does not contribute to pitch authority like canard can.

 

[F-15]

PAKFA needs thrust-vectoring on top of tailplane for pitch control, which is not a sign of LEVCON providing good pitch-authority. The LCA is just too small for anything. Neither helps your arguments.

Look i do not have time to waste, i will put it simple no aerodynamic single feature makes a fighter better, it is a combination of elements, tactics and pilot training what makes the wining pilot, Sukhoi said the PAKFA uses LEVCONS because they provide several advantages, among them, roll, pitch and vortex control, lower drag and Sukhoi has made S-47 and Su-37, Su-34 with canards, they know more than you. i do not need to waste time to convince you, so long see you.

 

[F-15]

Turn rate is not the same as pitch moment! No one is disputing that LEVCON does enhance lift, but LEVCON clearly does not contribute to pitch authority like canard can.

You are right, continue digging in Physics i do need to waste time, there is a relation between pitch moment and longitudinal stability ask F-16, see you

 

[Engineer]

Look i do not have time to waste, i will put it simple no aerodynamic single feature makes a fighter better, it is a combination of elements, tactics and pilot training what makes the wining pilot, Sukhoi said the PAKFA uses LEVCONS because they provide several advantages, among them, roll, pitch and vortex control, lower drag and Sukhoi has made S-47 and Su-37, Su-34 with canards, they know more than you. i do not need to waste time to convince you, so long see you.

Pilot training and tactics are not aerodynamics. They cannot alter parameters such as turn rates and lift-to-drag ratio, thus are of no concern in this thread.

Now back to LEVCON. Of course there are reasons why Sukhoi chose it, but that doesn't mean LEVCON is equivalent to or better than canard. Moreover, it is risky to design an aircraft with canard due to the requirement of very sophisticated FCS, which in turn requires a lot of devotion in money and time. Just because Sukhoi had developed canard designs in Soviet time, that doesn't mean they can repeat the same today. Given Russia needs an answer to F-22 quickly but with less money, LEVCON could just be a poor man's canard for Sukhoi, and does no prove LEVCON can do what canard can. I rest my case.

 

[F-15]

Pilot training and tactics are not aerodynamics. They cannot alter parameters such as turn rates and lift-to-drag ratio, thus are of no concern in this thread.

Now back to LEVCON. Of course there are reasons why Sukhoi chose it, but that doesn't mean LEVCON is equivalent to or better than canard. Moreover, it is risky to design an aircraft with canard due to the requirement of very sophisticated FCS, which in turn requires a lot of devotion in money and time. Just because Sukhoi had developed canard designs in Soviet time, that doesn't mean they can repeat the same today. Given Russia needs an answer to F-22 quickly but with less money, LEVCON could just be a poor man's canard for Sukhoi, and does no prove LEVCON can do what canard can. I rest my case.

Good, very good but you know you do not convince me

Please, Log in or Register to view URLs content!

give it a read and later we talk

 

[Engineer]

You are right, continue digging in Physics i do need to waste time, there is a relation between pitch moment and longitudinal stability ask F-16, see you

The existence of an relationship between two things do not make the two equivalent. It is the degree of that relationship that is important. For that reason, turn rate, pitch moment, and longitudinal stability exist as separated terminologies. While LEVCON contributes to the vertical component of lift, that is not the same as providing pitch authority in a significant way like canard does. So, by doing less, LEVCON cannot be said to be equivalent or better than canard.

 

[Engineer]

Good, very good but you know you do not convince me

Please, Log in or Register to view URLs content!

give it a read and later we talk

If you actually have studied those lecture slides carefully, you would have realized that pitch moment generated by a surface is a function of moment arm length. On page 18, they gave an example for moments generated by wing and tailplane:
m = m[sub]0[/sub] + L[sub]w[/sub] l[sub]w[/sub] + L[sub]t[/sub] l[sub]t[/sub]

In short, the longer the moment arm, the larger the pitch moment. Hence, LEVCON being much closer to the aircraft's center-of-gravity than long-coupled canard cannot generated as much pitch moment. This is exactly what I have told you in the beginning. I rest my case.