J-20 5th Generation Fighter VII

Status
Not open for further replies.
I

Inst

Captain
Here's another fun fact. The F-15E Strike Eagle? Apparently when you tack on only 60% internal fuel + 1000 kg of missiles, and go with F100-PW-229 engines, the aircraft has a 1.39 T/W ratio, compared to the 1.26 T/W of the F-15C. How's that for a strike aircraft? The Wikipedia listed T/W is only accurate for a full strike load, not an interception mission. The wing loading, definitely, is going to increase, but here's the thing. Low wing loading is good for sustained turn rates, but STR is also a function of T/W (energy bleed-off is compensated for by greater energy insertion by larger engines). High wing loading, on the other hand, is good for instantaneous turn rates. In other words, the F-15E Strike Eagle might be a more competent dogfighter than the F-15C.

In other words, when you make a strike aircraft out of an air superiority aircraft, capability in air superiority doesn't need to diminish, but can actually increase. A "strike" J-20 can simply be considered as a better J-20, period.
 
Last edited:
O

ougoah

Brigadier
Registered Member
Inst said:
Here's another fun fact. The F-15E Strike Eagle? Apparently when you tack on only 60% internal fuel + 1000 kg of missiles, and go with F100-PW-229 engines, the aircraft has a 1.39 T/W ratio, compared to the 1.26 T/W of the F-15C. How's that for a strike aircraft? The Wikipedia listed T/W is only accurate for a full strike load, not an interception mission. The wing loading, definitely, is going to increase, but here's the thing. Low wing loading is good for sustained turn rates, but STR is also a function of T/W (energy bleed-off is compensated for by greater energy insertion by larger engines). High wing loading, on the other hand, is good for instantaneous turn rates. In other words, the F-15E Strike Eagle might be a more competent dogfighter than the F-15C.
Click to expand...

You forgot to state whether the SE has high or low wing loading and you forgot to make clear whether STR or ITR is better for dogfighting and why. Do you mean both are good? Or if a compromise is necessary due to favouring one wing loading, then which one is it? Full of empty facts and making conclusions from thin air.

Strike aircraft doesn't mean it can't be a competent air superiority too that's true. But strike aircraft typically will ideally want all the following; high payload (J-20 fails here if stealth is to be preserved), a huge range of air to ground weaponry (can't fit internally with J-20), low speed and low attitude handling for navigating tricky terrain while keeping altitude as low as possible (we know J-20 is designed to excel in supersonic speeds which usually means poor low speed handling).

J-20 can use stealth to compensate for needing to fly low and there is definitely usefulness with J-20 as a limited strike fighter, delivering small but important hits on well protected targets deeper into territory without convincing air dominance. That's it though. It is definitely not a replacement for JH-7A or J-16 when it comes to performing strikes for PLAAF.
 
Last edited:
I

Inst

Captain
ougoah said:
You forgot to state whether the SE has high or low wing loading and you forgot to make clear whether STR or ITR is better for dogfighting and why. Do you mean both are good? Or if a compromise is necessary due to favouring one wing loading, then which one is it? Full of empty facts and making conclusions from thin air.

Strike aircraft doesn't mean it can't be a competent air superiority too that's true. But strike aircraft typically will ideally want all the following; high payload (J-20 fails here if stealth is to be preserved), a huge range of air to ground weaponry (can't fit internally with J-20), low speed and low attitude handling for navigating tricky terrain while keeping altitude as low as possible (we know J-20 is designed to excel in supersonic speeds which usually means poor low speed handling).

J-20 can use stealth to compensate for needing to fly low and there is definitely usefulness with J-20 as a limited strike fighter, delivering small but important hits on well protected targets deeper into territory without convincing air dominance. That's it though. It is definitely not a replacement for JH-7A or J-16 when it comes to performing strikes for PLAAF.
Click to expand...

Point is that it's possible to get a J-20 derivative provided that WS-15 are mature that's both strike-worthy and a strong air superiority fighter. That's why I think arguments against a strike J-20, outside the fact that the most evidence we have is "Chengdu wants to do a strike J-20", are not sound. A strike J-20 with 90% or higher of the J-20's aerodynamic performance (i.e ,tailfins go, slightly greater weight, greater payload) is arguably a better air superiority fighter than the current J-20, not least because the current J-20 lacks WS-15, simply because the air-to-air missile payload is larger and more flexible.
 
R

Richard Santos

Captain
Registered Member
A strike variant of j-20 will need WS-15 less than the air superiority variant. So I think whether WS-15 overcomes it’s hurdles will have little bearing on whether the strike variant of J-20 is developed and deployed.

f-15E retained f-15’s air to air capability only as an accident. F-15E’s airframe was minimally changed from F-15C’s. most of the concessions to the strike role is incorporated into the avionics, a WSO taking the place of the instructor in the equally air combat capable F-15D conversion trainer, and detachable FAST packs. Remove the fast packs the F-15E is practically the same aircraft as the F-15C/D with upgraded avionics. that‘s why F-15E retained very good air-to-air capability, in theory.

in theory because the removable FAST packs needed to support its strike missions are in practice never removed. With FAST pack installed it’s air combat Kinematic performance is significantly reduced.

can J-20 adopt the same solution? Perhaps. But there are fewer obvious places on the J-20 where a large external conformal pack can be stuck, still fewer if stealth performance were not to be compromised. I suspect significantly enlarging the belly weapon bay will be a major manufacturing change, and will permanent affect the aircraft’s performance and stealthiness. So my hunch is a j-20 with significant upgrades required to enable it to maintain or even extend current mission radius while carrying a substantial ATG Weapon load without compromising stealth will have to compromise its kinematic performance. So it’s stealthiness and internal weapon carriage means the J-20 can not be so readily adopted for serious strike role without substantial compromises to some element of its air to air potential.
 
A

AndrewS

Brigadier
Registered Member
Inst said:
Here's another fun fact. The F-15E Strike Eagle? Apparently when you tack on only 60% internal fuel + 1000 kg of missiles, and go with F100-PW-229 engines, the aircraft has a 1.39 T/W ratio, compared to the 1.26 T/W of the F-15C. How's that for a strike aircraft? The Wikipedia listed T/W is only accurate for a full strike load, not an interception mission. The wing loading, definitely, is going to increase, but here's the thing. Low wing loading is good for sustained turn rates, but STR is also a function of T/W (energy bleed-off is compensated for by greater energy insertion by larger engines). High wing loading, on the other hand, is good for instantaneous turn rates. In other words, the F-15E Strike Eagle might be a more competent dogfighter than the F-15C.

In other words, when you make a strike aircraft out of an air superiority aircraft, capability in air superiority doesn't need to diminish, but can actually increase. A "strike" J-20 can simply be considered as a better J-20, period.
Click to expand...

Thrust/Weight Ratio and dogfighting is no longer a relevant metric for Air Superiority.

That is based on the high lethality we see on all-aspect infrared missiles having the capability to lock-on after-launch.
 
broadsword

broadsword

Brigadier
AndrewS said:
Thrust/Weight Ratio and dogfighting is no longer a relevant metric for Air Superiority.

That is based on the high lethality we see on all-aspect infrared missiles having the capability to lock-on after-launch.
Click to expand...

It sure helps and is good to have, so it is still relevant.
 
I

Inst

Captain
Richard Santos said:
A strike variant of j-20 will need WS-15 less than the air superiority variant. So I think whether WS-15 overcomes it’s hurdles will have little bearing on whether the strike variant of J-20 is developed and deployed.

f-15E retained f-15’s air to air capability only as an accident. F-15E’s airframe was minimally changed from F-15C’s. most of the concessions to the strike role is incorporated into the avionics, a WSO taking the place of the instructor in the equally air combat capable F-15D conversion trainer, and detachable FAST packs. Remove the fast packs the F-15E is practically the same aircraft as the F-15C/D with upgraded avionics. that‘s why F-15E retained very good air-to-air capability, in theory.

in theory because the removable FAST packs needed to support its strike missions are in practice never removed. With FAST pack installed it’s air combat Kinematic performance is significantly reduced.

can J-20 adopt the same solution? Perhaps. But there are fewer obvious places on the J-20 where a large external conformal pack can be stuck, still fewer if stealth performance were not to be compromised. I suspect significantly enlarging the belly weapon bay will be a major manufacturing change, and will permanent affect the aircraft’s performance and stealthiness. So my hunch is a j-20 with significant upgrades required to enable it to maintain or even extend current mission radius while carrying a substantial ATG Weapon load without compromising stealth will have to compromise its kinematic performance. So it’s stealthiness and internal weapon carriage means the J-20 can not be so readily adopted for serious strike role without substantial compromises to some element of its air to air potential.
Click to expand...

If you look at what happened with the F-15E, newer and more powerful engines gave the F-15 approximately the same kinematic performance as the F-15C. Likewise, a WS-15 is going to add around 20-33% more power to the J-20, allowing it to compensate for additional weight in a strike modification.

FAST packs, likewise, are better off actually fitted on the inside of the J-20; i.e, they can take up weapons bay room to provide stealthy range enhancement. But that's assuming the weapons bay is large enough for such a thing to work, or in other words, you'd have to be able to pack a J-20A/B missile payload while including internal weapons bay fuel pods.
 
Status
Not open for further replies.
Top