Purely in terms of firing sequence, the door probably doesn't need to close once it's opened. However, for the sake of maneuvering with the missile exposed, closing the door yields aerodynamic benefits.
J-20 5th Gen Fighter Thread IV (Closed to posting)
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plawolf
Lieutenant General
Opening the weapons bays doors creates a lot of drag, negatively affecting the performance of the fighter when agility is at its most important.
Even with the fastest motors, opening the weapons bay doors would require a slight delay before you can launch the missile. With the Raptor as it is now, the delay is even longer because it does not have HMS, so no LOAL, meaning the Raptor need to stick its Sidewinders out long enough for their seekers to give a tone lock before it can launch.
In a dogfight where fractions of seconds matter, that delay could make all the difference. But if/when the Raptors get HMS and AIM9X, it can fire the missiles in LOAL mode, so the only delay is the time it takes to open the weapons bays, which will be a big improvement.
Having the ability to temporarily mount the SRAAMs externally with minimal RCS and drag penalties means the J20 is not reliant on LOAL. Don't get me wrong, LOAL is a great feature, and I hope and expect the PL10 to have it, but it is not without its drawbacks.
Firstly, missiles need to manage their energy just like fighters. Off broadside engagement capability is great, but the same missile making an extreme turn immediately after launch is going to be wasting a lot of its precious fuel and energy compared to if it was making a relatively straight flying shot.
The flight time immediately after launch is very critical for a missile because that is when it is programmed to burn most of its fuel very quickly to reach its designed speed ASAP. If the missile is wasting much of that time making hard turns, its range is going to suffer as well as its speed. All of that combined to mean that the same missile will be easier to dodge or outrun if it just performaned an extreme turn wasting much of its fuel, speed and range.
Secondly, LOAL requires that the pilot keep the target in his sights after missile release until the missile itself has acquired the target. The number one rule of dogfighting is never stick with a target to verify a hit/kill, and the second rule is that its what you don't see that kills you so obs are key. Yet LOAL forces you to break both rules in order to get a lock. If you had your missiles mounted conventionally, you would have fired and been away scanning around your plane for threats and targets straight away instead of wasting a few precious seconds more having to keep the target in your sights to guide the missile till it has a lock.
Thirdly, LOAL is more risky and likely has a lower PK ratio since the pilot has to judge himself when is a good time to launch the missiles. So that's something else that could go wrong to spoil the shot. When you are only carrying two SRAAMs, messing up a shot can be extremely costly.
Thus, even if the PL10 has perfectly good LOAL functionality, in most cases, it would be preferable to get a conventional lock and fire the missile straight forwards at a target instead of making it pull extreme turns to get a lock in the first place.
The NEZ and the number of Gs a target can pull and still be successfully hit by a missile is calculated based on it being at its optimal speed and energy state. The missile would unlikely be at its optimal speed and energy state if it spent the first few precious seconds of flight, which it normally uses to get itself up to its optimal speed and energy state, making a sharp turn to get a lock.
In many ways, LOAL is kinda like a cobra or TVC induced extreme post stall turn - it can be useful, but in most cases, you are just wasting airspeed and energy and putting yourself in a worse position than if you didn't bother using it in the first place.
The key, which separates the great pilots from the average ones is that the great pilots would know to use TVC and LOAL sparingly and subtlety to work with, and enhance the plane and missile's own agility instead of treating them like a silver bullet and expect them to do all the work and magically make everything easy.
I keep saying you are a "bright lad" wolfie, very nice post, and very good point, and the F-22 and F-35 can launch at very high Mach numbers, so the simple, clean, short doors, are not quite as draggy as it might seem, nor is RCS as much of a concern once the furball begins. While G2A might spot the momentary blip, it is unlikely that airborne radar would be able to achieve a positive LOCK in the seconds before and after launch. You are right on the A2A missle launched at a high mach expends far less energy accelerating and has greater speed and range, and kill probability definetly goes UP.Now the J-20 mechanism may be genious, or it may be a solution for a problem that doesn't exist, we shall see soon enugh! Brat
airsuperiority
Captain
Nope, but it's enough to get your attention. I don't want to use my best and hurt your health further lol.
Relax Air, its ok, Kroko is just in one of his moods, I'm sure the WS-15 will be rolled out soon enough, with the secrecy we've seen with the military in the last six months, all of us are a little cranky and impatient. If in fact they roll out with 2003, I will expect some hi-fives. It could well explain the aft fuselage rework and the time lag we've been experiencing lately.....It is amazing that some jack-leg, is standing down our military, while trying to project power, so don't feel too bad. Guy's lets remember, we are all on the same team, socio-paths in leadership---hurt us all, and make us less ready, if in fact we should be confronted by evil, as has happened far to many times in history! Brat
As our Benjamen Franklin so aptly stated, "we must all hang together, or we most certainly will hang separately"!
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drunkmunky
Junior Member
but... my comment was about RCS....
It might be a little aerodynamically cleaner, and it looks kool, in a world where no real rcs data will ever likely escape, thats all that matters, -----perception-----as you have intimated, yes its a complex solution that looks complicated, but it might fool the laymen into believing its WAY better and it is different "LOOKING", this is more important if your designs look like you "borrow" others technology frequently....................
So yes, I agree, and it "could be better", but is likely a smoke and mirrors deal,,,,,, why I am still LMBO,,,,, with the Navy's new sixth gen,,,,, which is now my screen saver,,,,,, even though I deplore tailess aircraft, it will grow a tail, just like the J-20 did,,,,, so one of you PS gurus, please PS me a set of J-20 ruddervators onto the new Navy bird. Brat
Place them on the aft fuse, slightly ahead of the nozzles, so the junction is on the aft fuse, sheltered by the outer nacelles on either side if you please, and use the Jolly Rogers insignia on each one please???? Brat
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Theoretically, the advantage is that once the door is closed, the RCS is less than a constantly open one.
Practically, as others have said, if the situation requires those doors to be opened in the first place, it's long past the time to be hiding behind stealth.
airsuperiority
Captain
I was just trolling(playing around), but I just find it funny he actually took it so serious. Cultural share of the day: In Hong Kong, we have an expression in the contemporary culture that goes, "If you take it serious, you lose". In other words, if you get all worked up over what's not meant to be taken seriously(perhaps deliberate trolling, deliberate flamebaiting), then you fall for the other person's sinister plans and make yourself a fool. This can usually apply to practical jokes, pranks, unintentional irritating behavior of some people who simply will never change because they're stuck that way without realizing and don't mean to actually upset anyone, or sinister-wise, a deliberate provocation that attempt to invoke a certain reaction from the victim.
Well anyways as for the WS-15 news up there, I checked its source and found one from Baidu, so it brings the question of where this article came from.
And another question that I have is, if huitong states the 2003 is no longer a "technology demonstrator", does that mean 2003 will be what we anticipate the production J-20 will be like approximately? (I doubt the 2003 will be too different from 2001 and 2002 except the aft section and other things that are meant to be experimental that are used on the first 2 models)
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Right, they sure like to keep us guessing, and as I have suggested before, I kinda had things wired in my thinking, but sequestration, John Kerry--JOKER--s R wild, New guv in Bejing--ace's wild??????, Liaoning to new base, which really isn't a base?????? J-20 ?????s NK???????,,,,, and thats just the big things we know something about???? Brat
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