J-20 5th Gen Fighter Thread V

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Quickie

Quickie

Colonel
Air Force Brat said:
Now Mr. Siegecrossbow,,,, those Russian RD-93s are NOT pushing AVICs little "proof of concept bird" past supersonic in dry thrust, maybe with burner,,,of course, and maybe once you're at MACH 1.8 or whatever, you can pull it out of burner and coast for some little distance before you drop under MACH 1???

Heck the F-35 will do that, and probably the J-20 as well, but not ONE of the three of these birds are exceeding MACH 1 in dry thrust,,,, unless they are pointing straight down??? LOL

In level flight, trimmed up nicely,, neither of these three ladies will pop Mach 1 with their current powerplants?? just not gonna happen, maybe if they drop the F-117s in the J-20 it will?? maybe will I would say?, supposedly the T-50 will??

I rather doubt we disagree on much, but the laws of physics, God's law, natural law?? whatever you want to call it, doesn't really care what you say, or who you are, and even with the incredible thrust of the F-135 engine, in the F-35, it still is NOT ENOUGH to pop Mach 1...

Supercruise is the ability to exceed Mach 1 in level flight, in "dry thrust", the F-22 will do it, up to Mach 1.6 + which is outstanding, several other 4 gens, and supposedly the T-50 will allegedly supercruise as well...

I have no doubt that once the J-20 receives her WS-15s that she will likely be in the same neighborhood as the F-22,,, but I sincerely question that those AL-31FNs will push her past Mach 1?

apologies for being so forthright here, but I'd have to "see it?? to believe it"? drag goes up exponentially as airspeed increases, the faster you go, the more drag you induce by virtue of that same beautiful speed!
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latenlazy said:
So, how does a bird like the F-16xl supercruise then?
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Drag is directly proportional to speed square. A 14% reduction of speed from Mach 1.8(1.6) to Mach 1.55(1.37) would reduce the drag by about 26%.

How much bigger is the dry thrust of the F-22 engine than the AL-31FN? AT 26% difference, the J-20 could possibly super cruise at Mach 1.55(1.37), assuming both aircraft have similar drag coefficient.
 
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Deino

Deino

Lieutenant General
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Guys ... You are again in aerodynamics, semantics, politics and other off-topic discussions !

STOP: I just deleted nearly four pages of BS ! :mad:

It's really annoying. We have a dedicated aerodynamics thread ... so if You can't hold Your water, then there but please do not derail each and every thread with OT-post.

Deino
 
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J

jobjed

Captain
Deino said:
Guys ... You are again in aerodynamics, semantics, politics and other off-topic discussions !

STOP: I just deleted nearly four pages of BS ! :mad:

It's really annoying. We have a dedicated aerodynamics thread ... so if You can't hold Your water, then there but please do not derail each and every thread with OT-post.

Deino
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Could you ban b787? He's "mig29" who was previously banned and it's against the rules to make a second account. Also, a few years ago, a user called "cottageLV" or something got banned for consistently posting trash so it's actually a ban-able offence to not contribute anything useful.
 
Deino

Deino

Lieutenant General
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Guys ... please !!!!

Take this as a warning and either You stay on topic or get a ban.

I really have enough of these constant OT-post that are only going back and forth without content. :mad:.
 
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manqiangrexue

manqiangrexue

Brigadier
I don't think that the question here should be whether or not it's possible for an aircraft of J-20's size to attain mach 1 on engines with the dry thrust of AL-31. It's clearly possible; J-8 is over 70 feet long, uses 2 engines that produce max 69kN on afterburner, and can exceed mach 2. This was an aircraft designed in China several decades ago so China easily has the technology and know-how. J-20 is 68 feet, and although exact engine power unknown, the value should be thought of as 2 x between 75kN (for AL-31FN) and 86kN (for AL-41, since we do not know the value for the best AL-31variant). There is nothing impossible about a jet of this size with that much thrust flying at supersonic speeds, as shown by the J-8. However, whether or not J-20 actually does supercruise on AL-31 will have to depend whether it was designed to do it or if the engineers decided to sacrifice it to prioritize other areas.
 
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kurutoga

Junior Member
Registered Member
manqiangrexue said:
I don't think that the question here should be whether or not it's possible for an aircraft of J-20's size to attain mach 1 on engines with the dry thrust of AL-31. It's clearly possible; J-8 is over 70 feet long, uses 2 engines that produce max 69kN on afterburner, and can exceed mach 2. This was an aircraft designed in China several decades ago so China easily has the technology and know-how. J-20 is 68 feet, and although exact engine power unknown, the value should be thought of as 2 x between 75kN (for AL-31FN) and 86kN (for AL-41, since we do not know the value for the best AL-31variant). There is nothing impossible about a jet of this size with that much thrust flying at supersonic speeds, as shown by the J-8. However, whether or not J-20 actually does supercruise on AL-31 will have to depend whether it was designed to do it or if the engineers decided to sacrifice it to prioritize other areas.
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super-cruise is not vertical climb, the shape/drag is more important. Rafale has a weak engine but it can comfortably supercruise at M1.4. I certainly believe J-20 can super cruise especially after the pilots describe how J-20 functions at supersonic speed. Looks like J-20 is designed not for low speed airshow stunts, but for supersonic maneuvers.
 
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