J-20 5th Generation Fighter VII

My rule of thumb is that comparing platforms one on one is not useful. Any comparison must be with systems and logistics.

banjex said:

My rule of thumb is that comparing platforms one on one is not useful. Any comparison must be with systems and logistics.

Click to expand...

Well, at a tactical level it *is* useful. Your kinematics are part of your system after all. You can arrive at some decent rule of thumb for which planes become sitting ducks to which other planes at the merge (which is not a scenario you can dismiss because there inevitably will be situations where you need to complete the mission with a merge), like how wide the effective flight envelope is or how good your energy maneuverability is (the ability to conserve and recover potential energy while executing maneuvers). That said it’s also true that past a point of capability in a dogfight a lot more rests on tactical details of how you use your plane’s kinematics advantages without exposing its disadvantages, and that part is all tactical discretion and the pilot. It’s not imo a wasteful exercise to look at kinetic comparisons, and there are in general better and worse designs. The actual problem is people want a neatly packaged one size fits all answer for these comparisons when aerial combat itself is not a one size fits all domain.

manqiangrexue said:

The thing is to realize when there's no way to do something rather than try in crazy and irrelvant ways. This is the official stance of the forum and the mods who are experienced with military aviation all agree. It's better to leave an impossible and contentious task unattempted rather than to have several versions of disinformation out there which actually go against forum rules as it can cause members with opposite views to clash with their own versions of disinformation essentially turning the forum into a dumpster for such useless things. That would severely degrade the professionalism here so the rule is to never undertake A vs B (vs C vs D) comparisons between aircraft. I think the most constructive advice here is to not attempt to do it.

Click to expand...

My method of setting up a table and assigning numbers might seem oversimplified but still,
it's valid doing A/B comparisons on certain aspects of performance or sub-system.
It could be contentious but we can have some sort of consensus after the debate.
That's what the forum is for. I don't see how it is against forum rules unless people start cursing or derailing the topic.

I would never dream of insert these numbers and decide who wins or loses in an actual fight because the outcome depends on so many variables.
Rather it gives a general idea of what level of performance each aircraft is at.

minime said:

My method of setting up a table and assigning numbers might seem oversimplified but still,
it's valid doing A/B comparisons on certain aspects of performance or sub-system.
It could be contentious but we can have some sort of consensus after the debate.
That's what the forum is for. I don't see how it is against forum rules unless people start cursing or derailing the topic.

I would never dream of insert these numbers and decide who wins or loses in an actual fight because the outcome depends on so many variables.
Rather it gives a general idea of what level of performance each aircraft is at.

Click to expand...

But your numbers don't do that. They're not just oversimplified; they're wrong (or based on nothing substantial) very often. F-22's main strength is frontal RCS reduction but you gave it a 4. Others such as supercruise, you basically randonly assigned a 2 to the J-20. We don't even know if it does this or not. Those are just 2 glaringly odd things I saw but there are so many more; basically it's harder to find something that looks like it makes sense than finding errors. Your numbers unfortunately do not give any general idea; they look like you're making up video game profiles for the next Ace Combat.

To assign overall value numbers and comparing them to each other is A vs B, which would have been against the rules even if they make sense but your table doesn't make sense in any regard as you assign integers by personal feel for unknown values and then weigh them through an arbitrarily created percentage system.

This forum encourages civil debate only under the condition that it does not erode the professionalism and value of the thread. A table like that I would expect to see on Reddit done by a fanboy with too much time. It's not for here.

taxiya said:

I was aware of this thought when I read the article. The ultimate question is what is the lift coefficients of J-20 and F-22 through the whole range of their AOA. Which we don't have for either J-20 or F-22. So the notion of "F-22 is better in sustained turn than J-20" is unfounded at least.

Here is the wind tunnel test outcome from CAC. Vertical axis is lift coefficient. Horizontal axis is AOA. Note, this is an early model of CAC 4th gen design with underside intake, otherwise same as J-20. The real figure of J-20 may differ. The model's wing AR=3, swept 45 degrees.

I will not use it as an argument but I remember reading another paper saying that J-20's lift coefficient is higher than XXXX or being the highest. I will post it if I find the paper again.

View attachment 96545

Click to expand...

Just the lift coefficient is not enough, you need drag coefficient versus AoA as well to tell the whole picture. It is possible that J-20 has higher max lift coefficient at a certain AoA but also has higher drag as well.

Self-explanatory.

manqiangrexue said:

But your numbers don't do that. They're not just oversimplified; they're wrong (or based on nothing substantial) very often.
This forum encourages civil debate only under the condition that it does not erode the professionalism and value of the thread. A table like that I would expect to see on Reddit done by a fanboy with too much time. It's not for here.

Click to expand...

Well, isn't caret inlet on F-22 a liability on frontal RCS?
And the statment saying F-35 is more stealth than F-22 seems to keep popping up in recent years.
On the supercruise side, I figure if Typhoon/Rafale can claim to be supercruise, why not J-20?
It's just not on the same level as F-22 though, that's why I put a 2.

Talk about too much free time and unprofessionalism, I wonder how many people on this forum are making a living on writing military content or aero engineer as a day job?
Let the Mod be the judge of that.
Other than that, I'm happy if you can break down more into how wrong I am on the numbers.

minime said:

Well, isn't caret inlet on F-22 a liability on frontal RCS?
And the statment saying F-35 is more stealth than F-22 seems to keep popping up in recent years.
On the supercruise side, I figure if Typhoon/Rafale can claim to be supercruise, why not J-20?
It's just not on the same level as F-22 though, that's why I put a 2.

Talk about too much free time and unprofessionalism, I wonder how many people on this forum are making a living on writing military content or aero engineer as a day job?
Let the Mod be the judge of that.
Other than that, I'm happy if you can break down more into how wrong I am on the numbers.

Click to expand...

Ok ... all this guesswork based on randomly given numbers like in a quartett's game have no relation to the J-20 ... as such, this must end and therefore can be continued in a separate thread maybe here: Aerodynamics thread ... or a new one!

minime said:

Other than that, I'm happy if you can break down more into how wrong I am on the numbers.

Click to expand...

Real life is not ace combat. The very notion of giving "percentage weightings" of the value of a fighter aircraft's performance in various domains is idiotic, and trying to compare it between two different aircraft is egregious.

My advice for you right now is just to stop. Just stop.

Deino said:

Impressive ... does he has a FB, Twitter or Weibo account? I would like to contact him.

Click to expand...

His Weibo account:

weibo.com/u/5470346735