J-20... The New Generation Fighter III

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no_name

Colonel
Quickie said:
I did try to estimate the G in the half turn but it turns out to be quite a bit over what a pilot can stand, so I figure it must the error in my trying to judge the distance by eye alone. :p (I didn't use a ruler.)
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It is probably not as much as you think, as the g force in this case is centripetal force and is not only dependent on the turn radius but also the tangential speed (to the square, in fact), which is not that large in the latter half turn.

If the pilot banked into a tight turn immediately at the start then he would have experienced bigger g force, but actually the looser half turn at the start already slowed the aircraft somewhat, so the plane is playing tricks on you on how agile it seems to turn.

I think that particular maneuver probably reveals more about the plane's low speed handling rather than its maneuverability, which would depends quite a lot on what engines it gets eventually.
 
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Quickie

Quickie

Colonel
no_name said:
It is probably not as much as you think, as the g force in this case is centripetal force and is not only dependent on the turn radius but also the tangential speed (to the square, in fact), which is not that large in the latter half turn.

If the pilot banked into a tight turn immediately at the start then he would have experienced bigger g force, but actually the looser half turn at the start already slowed the aircraft somewhat, so the plane is playing tricks on you on how agile it seems to turn.

I think that particular maneuver probably reveals more about the plane's low speed handling rather than its maneuverability, which would depends quite a lot on what engines it gets eventually.
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Lol, of course I know the g force is the centrifugal force w.r.t the pilot in the turn. I was trying to estimate the g at only the tight half turn in the 6 seconds or thereabout. From the banking to the start of the tight half turn, the distance is too small to have a significant slowdown in the speed. The change in the speed or more correctly the velocity of the aircraft takes place almost entirely in the time of the tighter part of the turn itself .i.e. the tight half turn when the aircraft was turning back.
 
L

latenlazy

Brigadier
Inst said:
As far as I can tell, the turn is 270 degrees, not 360, so if you extrapolate from that it's 27 degrees per second instantaneous turn.

In any case, the plane is too close to its minimum speed for the turn rate to mean anything; if you look at how closely the aircraft turns, one is surprised it doesn't simply drop out of the sky. The J-20, unfortunately, doesn't seem to be particularly remarkable aerodynamically under the present circumstances. It still wants more powerful engines and engines with TVC for us to see its true performance.
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The plane is still in testing, so I'd be somewhat surprised if it's being pushed to its limits right now.
 
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Player99

Junior Member
latenlazy said:
The plane is still in testing, so I'd be somewhat surprised if it's being pushed to its limits right now.
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Limit-pushing won't happen in Chengdu anyway. That's what Yanliang is for. And as Inst suggests, this is but a prototype in development, still evolving incrementally. What's more important, the engines installed are not WS-15 yet.

So any manuveoring we see happening in Chengdu's skies, would only be a reflection of what the aircraft will be capable of.
 
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Player99

Junior Member
Quickie said:
Lol, of course I know the g force is the centrifugal force w.r.t the pilot in the turn. I was trying to estimate the g at only the tight half turn in the 6 seconds or thereabout. From the banking to the start of the tight half turn, the distance is too small to have a significant slowdown in the speed. The change in the speed or more correctly the velocity of the aircraft takes place almost entirely in the time of the tighter part of the turn itself .i.e. the tight half turn when the aircraft was turning back.
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We are quite in sync! We both just want to know what G force the pilot or the aircraft was experiencing during that part of the turn, Not what G the aircraft can ultimately sustain.
 
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Player99

Junior Member
Inst said:
AFB:

I think the way I'd prefer to think of the J-20 is as a developmental aircraft. It's designed to be upgraded and for its capabilities to transform dramatically when upgraded with the latest technology.

With the current level of technology, it's a pure interceptor. It doesn't have enough T/W / maneuverability to be extremely capable as a dogfighter.

With improved engines, it's an air superiority aircraft. Without T/W being the limiter on the aircraft, it should be an extremely competent interceptor, with strong radar and BVR capabilities mixed with high degrees of agility in trans-sonic.

With improved engines and mature TVC, then, you could potentially rework the aircraft to drop the tailfins altogether and end up with a 6th-generation-like tailfinless aircraft with enhanced stealth and agility.
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Well, it's a prototype now. When it gets mass inducted, say by 2017, it will have the WS-15 installed, hence "extremely capable" of being a dogfighter as it was designed to be. That's what I gathered from all that's floating on the Internet, anyway.

If it gets mature TVC, it probably not only can get rid of the taifins but even the canards, as I recall someone saying Dr. Song saying that the canards are there more or less as a failsafe in case the TVC fails.
 
siegecrossbow

siegecrossbow

General
Staff member
Super Moderator
When the Su-27 first entered PLAAF it was considered too "precious" to be used as a dog-fighter. Its primary job during the Taiwan Strait crisis was intercepting enemy AWACs instead of directly engaging enemy fighters. The same could be said of the J-20 in the introduction phase. Utilizing the advantage of stealth to take out enemy force multipliers should be a priority.
 
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Inst

Captain
Player_99:

There are no guarantees that any part of the R&D process will go as expected. The J-10 was designed to fly with the WS-10, back in the 80s, but here we are in 2010 and the J-10B with WS-10A/B engine hasn't been inducted into the PLAAF yet.

I think that's the assumption made with the J-20 and J-31 systems; if something goes wrong with the R&D, the aircraft won't be crippled; you can still roll it out of the factory, but certain non-essential capabilities will be lost.

The J-31 is a basic twin-engine stealth strike fighter that's dependent on its stealth to win air combat engagements, not maneuverability. Compared to the F-35, it lacks the EODAS bells and whistles and all sorts of aggressive maneuverability requirements; the difficulty of R&D is orders of magnitude lower.

The same applies to the J-20. If the engines don't go through, you still have a capable stealth interceptor / strike fighter.

As is, we haven't heard anything on the WS-15 lately, we don't have pictures, and there's no indication that the WS-15 will launch on schedule and with full expected capabilities.
 
J

jobjed

Captain
¦^��: Re: J-20... The New Generation Fighter III

Inst said:
Player_99:

There are no guarantees that any part of the R&D process will go as expected. The J-10 was designed to fly with the WS-10, back in the 80s, but here we are in 2010 and the J-10B with WS-10A/B engine hasn't been inducted into the PLAAF yet.

I think that's the assumption made with the J-20 and J-31 systems; if something goes wrong with the R&D, the aircraft won't be crippled; you can still roll it out of the factory, but certain non-essential capabilities will be lost.

The J-31 is a basic twin-engine stealth strike fighter that's dependent on its stealth to win air combat engagements, not maneuverability. Compared to the F-35, it lacks the EODAS bells and whistles and all sorts of aggressive maneuverability requirements; the difficulty of R&D is orders of magnitude lower.

The same applies to the J-20. If the engines don't go through, you still have a capable stealth interceptor / strike fighter.

As is, we haven't heard anything on the WS-15 lately, we don't have pictures, and there's no indication that the WS-15 will launch on schedule and with full expected capabilities.
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Actually, at the very beginning, the J-10 was supposed to use a turbojet, or so I have read from an article posted a long time ago in the J-10 thread.
 
plawolf

plawolf

Lieutenant General
Inst said:
I think that's the assumption made with the J-20 and J-31 systems; if something goes wrong with the R&D, the aircraft won't be crippled; you can still roll it out of the factory, but certain non-essential capabilities will be lost.
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Exactly!

The J-31 is a basic twin-engine stealth strike fighter that's dependent on its stealth to win air combat engagements, not maneuverability. Compared to the F-35, it lacks the EODAS bells and whistles
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Did the X35 have EODAS and all the bells and whistles? The J31 we are seeing is only just the first prototype, and it would be silly to assume that the production version will not have something just because this first prototype does not have it.

and all sorts of aggressive maneuverability requirements; the difficulty of R&D is orders of magnitude lower.
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And you know this how exactly?

The same applies to the J-20. If the engines don't go through, you still have a capable stealth interceptor / strike fighter.

As is, we haven't heard anything on the WS-15 lately, we don't have pictures, and there's no indication that the WS-15 will launch on schedule and with full expected capabilities.
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And we have no indication that the project has been delayed or encountered any sort of technical difficulty that might cause a missed deadline or reduced capabilities.

Lack of knowledge/info is simply that and nothing more, especially when it comes to the PLA. There is no reasonable way to read any more into that absence of facts, and any attempt to do so will merely be a representation of your own hopes and fears.
 
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