J-20 5th Gen Fighter Thread V

[Engineer]

it seems you are an engineer just in forums

and turn radius improve dramatically with increased wing area, increased thrust, ...

Nowhere does your quote equates "bank" to "turn-rate". You aren't fooling anyone.

And unlike you, I need not to prove my credential because my words are not dependent on it. To expose that you know nothing, it is sufficient for me to point out the utter bollocks in your posts, which is as easy as stealing candies from an infant.

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 math

As long as J-20 has enough thrust-to-drag ratio, that's all that matter. The Concorde is heavier than F-22, yet Concorde can supercruise faster. Take-off weight and turn-rate are irrelevant for supercruise, so nice try with the

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.

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

You guessed, which is why so many of your claims are wrong. Reality isn't a guessing game.

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,

You would know, because that's how Russian salesmen speak to the crowd. Which is why "thrust-vectoring makes aircraft turn faster", "stealth is useless" and "China is buying Su-35" are nothing but Russian bollocks.

 

[Engineer]

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.

You may be interested to read the justification of J-20's aerodynamic configuration, written by the designer:

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[Quickie]

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....

On the contrary, it's exactly just that notion. The TVC are less advantages and may be more of a hassle for canard delta-wing aircraft. It's not coincidental all the contemporary canard delta-wing fighter jets, including the latest edition of the Typhoon have not been incorporated with TVC.

 

[Richard Santos]

It is quite unlikely that the drag and lifting coefficients of j-20 and f-22 would differ by anything close to 10% if their respective designers had aimed for the same the designers of f-22 and j-20 had aimed for the same ovjective. This is not 1948.

But the complexity of the design trade off means their designers could well have had different objectives. J-20 seem to have slightly better area rule fuselage design and may well have lower transonic drag.

You may be interested to read the justification of J-20's aerodynamic configuration, written by the designer:

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The fundamental disadvantage of conventional layout with regard to turn Rate is a conventionally positioned tailplane generates negative lift to pitch the aircraft up. This worsens the aircraft's lift coefficient during a turn.

The Canard on the other hand, generates added positive lift to pitch the aircraft up. This Improves the aircraft's lift coefficient during a turn.

So all else being equal, a conventional aircraft can be expected to have slightly worse lift characteristic than a canard aircraft during maneuver, which can only be compensated for by aeoptimg an appropriately high nose high pitch, or AOA, which imparts more drag, and require higher thrust to match in any sustained turn.

However, this effect is actually quite small in most of the flight envelope. A few percent at most. It only becomes more pronounced at very high angles of attack. Say 30 degrees. Fighters do not conduct sustained turns at 30 degrees AOA. The drag at 30 degrees AOA at typical combat speeds is so extreme the aircraft would rapidly slow and loss energy even with maximum afterburner .So,for the purpose of sustained turn Rate, canard vs conventional tail makes only a small difference, if all else are equal. It certainly would make less difference than the alleged 20-30% specific thrust advantage f-22 might at the first estimate enjoy.

So the upshot is canard offer real, but slight, advantage in energy maneuver combat. It may offer more advantage if the pilot is willing to lose energy by adopting excessive AOA, but advantage in this condition is unlikely to save the plane from an adversary practicing careful energy maneuver principles.

The purpose of TVC is not to adjust lift coefficient. It is to improve pitch Rate. So the advantage of canard design in no way interfere with the advantages of canards.

 

[b787]

Nowhere does your quote equates "bank" to "turn-rate". You aren't fooling anyone.

you flunked the test, welcome to my ignore list.

 

[b787]

I have little doubt the J-20, as it is now, is probably underpowered compared to the F-22, but simply assuming there is little difference between all these other variables, or that the F-22 must indeed be superior on some of these variables (like weight) without evidence is nothing more than unfounded speculation. It doesn't seem very consistent to set out objective standards of evaluation and then walk right over them based on poorly supported intuitions...

you are simply denying facts, longer fuselage means more volume, the J-20 is not lighter than the F-22, a longer fuselage with more volume only justifies more fuel, more weapons, a Delta is only used for high speed, the F-35 did not even out turn a heavy loaded F-16B, you are thinking stealth creates a lot of lift, it does not, F-22 relies in stealth to fight at long range, TVC nozzles to improve its aerodynamics, and supercruise to minimize radar exposure and reduce the no scape zone of the enemy missile; F-35 uses avionics and missiles to stay on top.
J-20 uses stealth to have the same BVR effect F-22 has, but has no super maneuverability, you can see it in the flight display no poststall, so like F-35 relies on helmet mounted sight and avionics.

Have you ever seen F-22s flying near S-400 batteries lately?

If stealth is so good how come Russia created a no fly zone in Syria? consider the F-22 has flown overthere

 

[Engineer]

you flunked the test, welcome to my ignore list.

LMAO! You simple have no argument, but sure, blame me for your own incompetence.

 

[dingyibvs]

you are simply denying facts, longer fuselage means more volume, the J-20 is not lighter than the F-22, a longer fuselage with more volume only justifies more fuel, more weapons, a Delta is only used for high speed, the F-35 did not even out turn a heavy loaded F-16B, you are thinking stealth creates a lot of lift, it does not, F-22 relies in stealth to fight at long range, TVC nozzles to improve its aerodynamics, and supercruise to minimize radar exposure and reduce the no scape zone of the enemy missile; F-35 uses avionics and missiles to stay on top.
J-20 uses stealth to have the same BVR effect F-22 has, but has no super maneuverability, you can see it in the flight display no poststall, so like F-35 relies on helmet mounted sight and avionics.

Have you ever seen F-22s flying near S-400 batteries lately?

If stealth is so good how come Russia created a no fly zone in Syria? consider the F-22 has flown overthere

Did you just say TVC nozzles improve aerodynamics? Also, coulda sworn volume is dependent on more than just length, but my 3rd grade mathematics is a bit fuzzy.

 

[Engineer]

The fundamental disadvantage of conventional layout with regard to turn Rate is a conventionally positioned tailplane generates negative lift to pitch the aircraft up. This worsens the aircraft's lift coefficient during a turn... The purpose of TVC is not to adjust lift coefficient. It is to improve pitch Rate. So the advantage of canard design in no way interfere with the advantages of canards.

Not that I disagree with what you've said, but those were not the points addressed by the paper.

 

[Engineer]

For benefits of other members, it is time again to pick apart more nonsense!

you are simply denying facts, longer fuselage means more volume, the J-20 is not lighter than the F-22, a longer fuselage with more volume only justifies more fuel, more weapons, a Delta is only used for high speed, the F-35 did not even out turn a heavy loaded F-16B, you are thinking stealth creates a lot of lift, it does not

This is a fallacy known as

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. Note how this person completely made up arguments, then proceed to argue against his own arguments.

F-22 relies in stealth to fight at long range, TVC nozzles to improve its aerodynamics

This is blatantly false. The main capability offered by thrust-vectoring is not having to rely on aerodynamics. In fact, the whole point is to offer control without changing aerodynamics.

and supercruise to minimize radar exposure and reduce the no scape zone of the enemy missile; F-35 uses avionics and missiles to stay on top.
J-20 uses stealth to have the same BVR effect F-22 has, but has no super maneuverability, you can see it in the flight display no poststall, so like F-35 relies on helmet mounted sight and avionics.

Super manoeuvrability is more correctly known as post-stall manoeuvrability, which refers to the ability to control the aircraft that has stalled. There is no requirement that the aircraft has fly stunts that the Russians do. This guy is once again changing terminology.

We do know that J-20 has post-stall manoeuvrability, since it is stated as one of the design requirements. This is achieved by canard, which retains its ability to control pitch even when the rest of the aircraft has exceeded the maximum AoA.

Have you ever seen F-22s flying near S-400 batteries lately?

If stealth is so good how come Russia created a no fly zone in Syria? consider the F-22 has flown overthere

To those who do not know and to those are new, this guy would argue that everything found on PAKFA is "good" and everything else on F-22 and J-20 as "bad". Since PAKFA is not a true stealth fighter, one argument involves claiming that "stealth is useless", which is what his rant above is all about. It is just a manifestation of not-made-here syndrome.