J-20 5th Gen Fighter Thread VI

[taxiya]

The odd thing is F-16 and F-15's are hidden while the F-22 is bulging. Why's the US, Russian and Chinese stealth air-superiority platforms having bulging ones? Flanker and JF-17 are hidden too.

Sorry for dragging on this item but the more I look at pictures the more intriguing it is.

My first thought is, if we compare the wing shapes of F-22, J-20, Su-57 and F-15, F-16, F-18, Su-27, I can see that the stealthy ones have bigger wings than the second group. I mean their wings are longer in the axis direction. That makes their wings to be thinner at the end, less room to house the actuator.

Second thought is, I have read somewhere that, the stealthy ones or more accurately the new fighters are using electrical actuators rather than hydraulic ones. Hydraulic actuators are more powerful than electrical ones given the same size, or more compact given the same force needed. The earlier aircrafts use hydraulic ones, smaller to be concealed. The electrical ones are better integrated to the FBW system and more responsive, able to be digitalized. The drawback is bulkier, but seems to be worth it.

 

[plawolf]

My first thought is, if we compare the wing shapes of F-22, J-20, Su-57 and F-15, F-16, F-18, Su-27, I can see that the stealthy ones have bigger wings than the second group. I mean their wings are longer in the axis direction. That makes their wings to be thinner at the end, less room to house the actuator.

Second thought is, I have read somewhere that, the stealthy ones or more accurately the new fighters are using electrical actuators rather than hydraulic ones. Hydraulic actuators are more powerful than electrical ones given the same size, or more compact given the same force needed. The earlier aircrafts use hydraulic ones, smaller to be concealed. The electrical ones are better integrated to the FBW system and more responsive, able to be digitalized. The drawback is bulkier, but seems to be worth it.

In my view, it’s to do with stealth.

The wings are the biggest part of a fighter aircraft.

If you want your plane LO, the wings must only give minimal radar returns or everything else you do to reduce RCS is going to be meaningless.

There are three main ways to limit LO; shaping, using RAM material, and using radar transparent materials.

Obviously shaping is important, but that only works for a narraw band in terms of incoming emission source. You cannot reply purely on shaping, because when the enemy radar moves out of that small shaping sweet spot, your RCS is going to ballon. OTOH, if you stealth shape-optimise your wings too much, they are going to become really bad at their main job of generating lift.

So, on top of shaping, you also need to use either RAM to cover the whole wing, or just make the wing out of radar transparent materials.

Applying RAM would create a huge weight penalty given the large area involved, so the best option is to make the wing out of radar transparent materials so radar waves pass right through and/or get absorbed by the fuel stored in the wings.

The problem with making the wing out of radar transparent materials is that if there are any internal structures that might reflect radar waves, (like an array of small actuators as used in those other 3rd and 4th gen fighters without ‘bulges’), well those will be largely exposed to incoming radar and will cause your RCS to spike massively.

The solution to that problem is to use one big actuator instead of an array of small ones, and house that single acuator in a stealth housing that is shape optimised for a wide range of incoming angles.

 

[taxiya]

In my view, it’s to do with stealth.

The wings are the biggest part of a fighter aircraft.

If you want your plane LO, the wings must only give minimal radar returns or everything else you do to reduce RCS is going to be meaningless.

There are three main ways to limit LO; shaping, using RAM material, and using radar transparent materials.

Obviously shaping is important, but that only works for a narraw band in terms of incoming emission source. You cannot reply purely on shaping, because when the enemy radar moves out of that small shaping sweet spot, your RCS is going to ballon. OTOH, if you stealth shape-optimise your wings too much, they are going to become really bad at their main job of generating lift.

So, on top of shaping, you also need to use either RAM to cover the whole wing, or just make the wing out of radar transparent materials.

Applying RAM would create a huge weight penalty given the large area involved, so the best option is to make the wing out of radar transparent materials so radar waves pass right through and/or get absorbed by the fuel stored in the wings.

The problem with making the wing out of radar transparent materials is that if there are any internal structures that might reflect radar waves, (like an array of small actuators as used in those other 3rd and 4th gen fighters without ‘bulges’), well those will be largely exposed to incoming radar and will cause your RCS to spike massively.

The solution to that problem is to use one big actuator instead of an array of small ones, and house that single acuator in a stealth housing that is shape optimised for a wide range of incoming angles.

I agree.

 

[kwaigonegin]

Exactly, this is just an attempt by the Indian Air Chief to assure the gullible masses under this capabilities gap. It is his job to give the impression of security for his nation. The nature of Indian media is very sensational, one day China is an aggressive superpower capable of anything, the next China is a paper tiger no threat to India. The statement really holds little meaning but the audience are not people who have an interest in this field.

Its not just that but he was also asked a relatively specific question in the public domain by likely very non technical folks. Whatever he says will also be broadcasted into the public domain. Again seen by mostly non technical and non military savvy folks.

I do not blame him for what he said. If I was in his position I would've likely said something very similar. He didn't give an outright lie, he just worded it in such a way where the masses 'think' they are kept informed and happily satisfied with his answers w/o knowing the nitty gritty of any actual capability gap.

I would honestly be SHOCKED to see a person like him says something to the effect of , ... No, unfortunately we do not have the ability to track, detect and destroy the J20 at standoff distances based on India's current air defense capabilities. Also since we do not have nor know the actual RCS of the J20 and it's defensive capabilities, it is not possible for us to determine an effective missile lock at a predetermined distance and to accurately and consistently maintain a lock-on at xxx distance.

No, no good air marshall, general or admiral will ever say something like that in the public domain for public consumption. LOL He will likely lose his job and nothing would've changed.

 

[Air Force Brat]

This way also combining the FC-31 + J-15 enables the PLANAF to get the kick the door down function of the J-20. FC-31 flies in front and cues the J-15 at the back. I remember Yang Wei in a recent video specifically saying the function of the J-20 as a kick the door down plane.

actually what he said was that the J-20 had far more potential than to just be classified as a "kick down the door" fighter aircraft, they same could be said of most 5th generation aircraft, they are multi-talented,, the real unknown here is who will come out on top in a mano-a-mano 5 Gen on 5 Gen melee!

 

[Air Force Brat]

Its not just that but he was also asked a relatively specific question in the public domain by likely very non technical folks. Whatever he says will also be broadcasted into the public domain. Again seen by mostly non technical and non military savvy folks.

I do not blame him for what he said. If I was in his position I would've likely said something very similar. He didn't give an outright lie, he just worded it in such a way where the masses 'think' they are kept informed and happily satisfied with his answers w/o knowing the nitty gritty of any actual capability gap.

I would honestly be SHOCKED to see a person like him says something to the effect of , ... No, unfortunately we do not have the ability to track, detect and destroy the J20 at standoff distances based on India's current air defense capabilities. Also since we do not have nor know the actual RCS of the J20 and it's defensive capabilities, it is not possible for us to determine an effective missile lock at a predetermined distance and to accurately and consistently maintain a lock-on at xxx distance.

No, no good air marshall, general or admiral will ever say something like that in the public domain for public consumption. LOL He will likely lose his job and nothing would've changed.

Exactly, the US military has "shut down" the extremely "yackety yack chatter", too much information out in public is used by the bad guys to build their own offensive or defensive capabilities,, President Trump and Secretary Mattis have shut down the "leakers",, all the military is under a gag order at present, and been told to "shut up" until we learn to keep information secure,,, about time!

 

[vincent]

actually what he said was that the J-20 had far more potential than to just be classified as a "kick down the door" fighter aircraft, they same could be said of most 5th generation aircraft, they are multi-talented,, the real unknown here is who will come out on top in a mano-a-mano 5 Gen on 5 Gen melee!

Hopefully we'll never have to find out

 

[Air Force Brat]

Hopefully we'll never have to find out

Exactly Vincent, and I appreciate your stating the obvious, the main reason in the nuclear age to maintain parity, is so that neither side has any doubt the other can defend themselves, the idea being that conflict will be more costly than the bad guy is willing to pay...

Now on an academic level, I would really like to know how these girls would "stack up" aerodynamically,, while the SU-57 is likely the most agile, it is also the least L/O, and honestly likely the first casualty??

The J-20 has taken many L/O cues from LockMart, and taken the aft mounted delta and distant coupled forward canard from others, and with the genius of Dr. Song and Yang Wei brought those apparently divergent concepts together in a new and uniquely Chinese front runner in the J-20... and that's the beauty of this airplane..

The Wright's used the first canard, on the first airplane, for pitch control! My point is no aircraft is ever going to be a straight clean sheet design,, aircraft design is like shopping and chopping,, you put everything in the basket, and then put back what you don't need or can't afford?? LOL

when LockMart brought the F-22 to fruition,, they Gathered their top engineers with Boeing and the other contractors gathered together and submitted designs one after the other until the twin tail, twin stabilator platform cam out on top, they tried "everything", until they come up with the optimum combination of capabilities...

one of the myths, even here on SDF, is that the best bird (YF-23) got pushed out because of cost, bias, bribery, conspiracy?? whatever, and that's simply NOT true, the YF-22 was, and IS the better airplane for at least a hundred different reasons... we built the right airplane! Now if someone came out tomorrow and said you can't build the F-22B, but we will let you build the YF-23B,, my checkbook would be on the counter so fast it would make your head spin!

So the J-20 and FC-31 are two very distinct and very outstanding platforms,,, they are complimentary, and that has always been the Genesis of the Hi/Lo pairing,, it does work!

 

[Air Force Brat]

In my view, it’s to do with stealth.

The wings are the biggest part of a fighter aircraft.

If you want your plane LO, the wings must only give minimal radar returns or everything else you do to reduce RCS is going to be meaningless.

There are three main ways to limit LO; shaping, using RAM material, and using radar transparent materials.

Obviously shaping is important, but that only works for a narraw band in terms of incoming emission source. You cannot reply purely on shaping, because when the enemy radar moves out of that small shaping sweet spot, your RCS is going to ballon. OTOH, if you stealth shape-optimise your wings too much, they are going to become really bad at their main job of generating lift.

So, on top of shaping, you also need to use either RAM to cover the whole wing, or just make the wing out of radar transparent materials.

Applying RAM would create a huge weight penalty given the large area involved, so the best option is to make the wing out of radar transparent materials so radar waves pass right through and/or get absorbed by the fuel stored in the wings.

The problem with making the wing out of radar transparent materials is that if there are any internal structures that might reflect radar waves, (like an array of small actuators as used in those other 3rd and 4th gen fighters without ‘bulges’), well those will be largely exposed to incoming radar and will cause your RCS to spike massively.

The solution to that problem is to use one big actuator instead of an array of small ones, and house that single acuator in a stealth housing that is shape optimised for a wide range of incoming angles.

I think you're on the right track here Wolfie, but I would probably state that there are three main tools to limit RCS, shaping, Radar absorbent structural meta materials, (radomes, leading and trailing edges) (all the leading fifth gens have meta material in strategic places), and finally coatings...on the MC-130E there was 400 pounds of "rubberized coatings" or paint applied to those 14 "Rivet Yards",,, that was considered insanely heavy, but that was a huge airplane..

All of those technologies together give you a very L/O bird that does NOT suffer aerodynamically,,, all you have to do is watch the flying demonstrations of the J-20, F-22, and F-35 to note that they fly very, very well, and each of these aircraft make a tremendous amount of lift, and have tremendous maneuverability,, but the "alien bird" in each of these girls are their very low RCS, and that my friend is the "magic mixture"!

 

[KlRc80]

actually what he said was that the J-20 had far more potential than to just be classified as a "kick down the door" fighter aircraft, they same could be said of most 5th generation aircraft, they are multi-talented,, the real unknown here is who will come out on top in a mano-a-mano 5 Gen on 5 Gen melee!

Agree but my point was that since Yang Wei said it could be more than a door kicker, it means that it is currently a door kicker which I presume that it's weapons bay is currently large enough to hold door kicker bombs.
And I assume that the FC-31's weapons bay are smaller than the J-20 so it probably can't carry as effective door kicker bombs.

But putting the FC-31 + J-15 gives stealth door kicking ability to a carrier air wing, something that a J-20 can do all by itself, which is sort of a compromise in return for lower cost and having more LO planes in the carrier air wing.