J-20 5th Gen Fighter Thread V
- Thread starter Deino
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What a year for China:
LM-5 first flight
J-20 LRIP
Y-20 enter service
Fastest super computer
First quantum satellite
First cold atom clock in space
500m telescope
ARJ enter service
TG-2 & Shenzhou-11
Not to mention 001A & 055 appearing.
China still has a long way to go and some people will continue to try to talk China down at every chance. But looking back 2016 might be the turning point where more and more people start looking at China in a different or more and more objective way. Deino certainly has been a positive in this process. For that I say, thank you!
LM-5 first flight
J-20 LRIP
Y-20 enter service
Fastest super computer
First quantum satellite
First cold atom clock in space
500m telescope
ARJ enter service
TG-2 & Shenzhou-11
Not to mention 001A & 055 appearing.
China still has a long way to go and some people will continue to try to talk China down at every chance. But looking back 2016 might be the turning point where more and more people start looking at China in a different or more and more objective way. Deino certainly has been a positive in this process. For that I say, thank you!
They're shielded on the ones that flew by Zhuhai, and the gun looks like it's on the right shoulder.
b787
Captain
it seems you are an engineer just in forums
For the benefits of other forum members here, let me point out the why the above statements are wrong.
First, banking does not equate to turning. Banking is not even a "rate" but a static measurement. Even roll-rate (the rate-of-change of banking) is not the same as rate-of-turn. The difference between the two is that rolling does not affect pointing direction of aircraft's nose, whereas turning does.
This is also the same guy who once argued intersecting lines/planes are parallel!
If the J-20 has Al-31s and has a take off weight equal to the F-22, something very unlikely, (sorry i forget you think it is lighter and smaller than F-22
), its turn rate is bigger just by mathi guess you flunked the test given to you by your proffesor Ovid, all the people who gave you likes have shown they never cared to read the last equation by this book
So get it, the J-20 to be superior needs higher lift than F-22 and higher thrust, your chinese General speaks to the crowds, in the same way the american general did,
Taxiya you thought i did not know Physics but i am an engineer by trade, not aeronautical but engineer
manqiangrexue
Brigadier
Oh, the fundamentals of physics LOL You must think that everyone who read physics 101 for dummies can be a fighter jet designer. Did it ever occur to you that the actual design of the aircraft, including materials, can have an impact? The J-20 was made from materials designed much later than the F-22 using newer production methods. Guessing J-20's weight based on size comparison F-22 is like guessing the mass of an unknown object based on it having the same volume as a known object (I know this one might be hard for you so think about it a couple times). And then, there are differences in aircraft design. Heavier jet must have higher lift and thrust than lighter jet in order to achieve the same results only applies if they're the same jets on different size scale. J-20 and F-22 are 2 different things completely. For example, a brick and a kite can weigh the same but they won't behave the same in the air even with similar thrust. Professor Ovid wouldn't make any stupid assumptions on "fundamental physics" because they are different mass, volume, density, shape, design, different things; he'd fail you for even trying.it seems you are an engineer just in forums
If the J-20 has Al-31s and has a take off weight equal to the F-22, something very unlikely, (sorry i forget you think it is lighter and smaller than F-22
i guess you flunked the test given to you by your proffesor Ovid, all the people who gave you likes have shown they never cared to read the last equation by this book
So get it, the J-20 to be superior needs higher lift than F-22 and higher thrust, your chinese General speaks to the crowds, in the same way the american general did,
Taxiya you thought i did not know Physics but i am an engineer by trade, not aeronautical but engineer
Turning in a fighter can be thought of as mainly a pitching movement. The fighter bank to align its plane of pitch movement with the plane of the desired turn. Once accomplished the fighter pitches up to increase the angle of attack, and the lift. It is the lifting force that accomplishes the turn.
However, pitching up greatly increases the drag. Without a compensating increase in thrust, a fighter pitching up would lose speed. If a fighter is losing speed as it turns, it could not sustain the turn Rate.
Therefore, somewhat simplifying, the maximum sustained turn Rate of a fighter at any given initial speed is the turn Rate where the drag of the pitched up fighter equals the maximum thrust delivered by its engines.
So in this B787 is regrettably, and extremely unusually and surprisingly, correct. When other factors are broadly similar, a fighter with a big advantage in available thrust to drag ratio can be expected to exhibit superior sustained turn Rate.
Sustained turn Rate is a measure of maneuverability. Therefore by this measure, f-22 is likely superior to the j-20 in maneuverability.
However, pitching up greatly increases the drag. Without a compensating increase in thrust, a fighter pitching up would lose speed. If a fighter is losing speed as it turns, it could not sustain the turn Rate.
Therefore, somewhat simplifying, the maximum sustained turn Rate of a fighter at any given initial speed is the turn Rate where the drag of the pitched up fighter equals the maximum thrust delivered by its engines.
So in this B787 is regrettably, and extremely unusually and surprisingly, correct. When other factors are broadly similar, a fighter with a big advantage in available thrust to drag ratio can be expected to exhibit superior sustained turn Rate.
Sustained turn Rate is a measure of maneuverability. Therefore by this measure, f-22 is likely superior to the j-20 in maneuverability.
I think TVC is more useful in aircraft layouts in which the pitching moment arm is towards the rear. i.e. via horizontal stabilizers, since TVC itself cannot be placed anywhere but at the rear near the exhaust.
Maybe that is why you see no forward canard-pitched (not just small trim canards like the Su-35) aircraft using TVC, and why J-20 final form is unlikely to utilize it. Instead it adopts aerodynamic solutions like close coupling between Canards and LERXs to achieve required lift at high AoA and lower stall speed.
Also lets not think that TVC is this end all be all thing. Lets not forget that variable swept wings were all the hype in the past, or how people think AAM would make gun mount unnecessary. Maybe more time is required to see if this is also a fad. Not discounting TVC, but current form of TVC, and also the fact that it may not be the only solution available to solve a problem.
Maybe that is why you see no forward canard-pitched (not just small trim canards like the Su-35) aircraft using TVC, and why J-20 final form is unlikely to utilize it. Instead it adopts aerodynamic solutions like close coupling between Canards and LERXs to achieve required lift at high AoA and lower stall speed.
Also lets not think that TVC is this end all be all thing. Lets not forget that variable swept wings were all the hype in the past, or how people think AAM would make gun mount unnecessary. Maybe more time is required to see if this is also a fad. Not discounting TVC, but current form of TVC, and also the fact that it may not be the only solution available to solve a problem.
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That's not right. If you look at the center of lift or center of mass in a typical canard fighter, it is at approximately the same place relative to the location engine exhaust or the length fuselage at those on a conventional tailed design. So the added pitch authority that can be gained through TVC would be about the same between a canard fighter and a conventionally tailed fighter.
It is essential to look past canards or tails, and see the entire airframe as a single complex integrated lifting body. What matters is where the center of mass or center of lift of the Entire lifting body is, not where the wing or tail is.
It is essential to look past canards or tails, and see the entire airframe as a single complex integrated lifting body. What matters is where the center of mass or center of lift of the Entire lifting body is, not where the wing or tail is.
If you look at where the main landing gear is on any fighter. That's approximately where the center of mass as well as center of lift of the entire aircraft is on the longitudinal axis. Compare where the main landing gear is on the f-22 vs those on the j-20. You see both are at roughly the same place. Now compare where the engine exhaust nozzles are. The distance between the engine exhaust nozzles and the main gear is approximately the moment arm available to any TVC nozzle on either fighter. You can see as an first order estimate TVC can give j-20's pitching moment at least as big a boost as they do on the f-22.
The fact that j-20 doesn't have TVC is unlikely to be attributable to the notion that TVC would be less useful or effective on the j-20 than on the f-22.
A different consideration must of animated the design decision. These might be;
1. Lack of a good TVC nozzle design
2. A view on weight vs performance tradeoff that did not accept the weight penalties of a TVC nozzle.
The fact that j-20 doesn't have TVC is unlikely to be attributable to the notion that TVC would be less useful or effective on the j-20 than on the f-22.
A different consideration must of animated the design decision. These might be;
1. Lack of a good TVC nozzle design
2. A view on weight vs performance tradeoff that did not accept the weight penalties of a TVC nozzle.
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Hyperwarp
Captain
For 1st time, Hui Tong is also gravitating towards AL-31F-M2
This is just his opinion, but he has got many things right in the past. For the record, for me, from day 1, I never believed the J-20 was equipped with a WS-variant. The only question for me was what variant of the AL-31F is it equipped with. If it is only equipped with the basic AL-31F (122kN) the J-20 maneuverability will be like a fat whale. Since the AL-31F-M2 lost out to the 117, it makes sense since the Russians won't be giving away their best engine. It is only the losing candidate. If PRC poured enough money into Salut, they could have produced a 140+ kN class engine for the J-20 as an interim solution. Salut gets investment and the Russians still keep the edge with 117. Salut is after all the company CAC has been working with for such a long time. We will see for real in a few years.
This is just his opinion, but he has got many things right in the past. For the record, for me, from day 1, I never believed the J-20 was equipped with a WS-variant. The only question for me was what variant of the AL-31F is it equipped with. If it is only equipped with the basic AL-31F (122kN) the J-20 maneuverability will be like a fat whale. Since the AL-31F-M2 lost out to the 117, it makes sense since the Russians won't be giving away their best engine. It is only the losing candidate. If PRC poured enough money into Salut, they could have produced a 140+ kN class engine for the J-20 as an interim solution. Salut gets investment and the Russians still keep the edge with 117. Salut is after all the company CAC has been working with for such a long time. We will see for real in a few years.
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