Wondering if they would still fire the 25x115 rounds as opposed to the much more powerful 30x165. J-10C's cannons still fire the "underpowered" 23x115 shells.
J-20 5th Generation Fighter VII
- Thread starter siegecrossbow
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I personally would like China to adopt a caliber smaller than 30mm because the ammunition capacity is notoriously low. Aircraft are not tanks; In a dogfight, a good burst from a 20mm is enough to cripple and down an enemy fighter. However, 20mm would not be good enough for destroying bombers. But I think its unnecessary for fighter jets to get close and engage bombers using cannons.
@Deino
This is relative to the flight combat characteristics of the J-20; i.e, Latenlazy's proposition is that the high supersonic agility is very useful for dodging missiles. My proposition is that it's more useful for strategic mobility and hit and run attacks.
@latenlazy
Ever seen an EM chart? At Mach 1.2, 9 G of acceleration is half the angular change of Mach 0.6 9 G. You're arguing that twice the speed and a quarter of the agility (in angular terms, and I'd rather see half the agility with TVC) provides the same difficulty in interception as half the speed but twice the agility. You can work this out in your head; use two circles with radius 2 being 1/2 that of radius 1. Then cut two circular segments; the first circular segment has an angle half that of the second circular segment. The chord length between radii should be the same.
Using agility to dodge missiles (i.e, a last ditch effort) is best done at low speeds, because drag is lower and loss of energy can be quickly recovered.
@siegecrossbow
A future laser defense pod could be paired; and a good laser system with 4km or so of range would completely outmode a gun except in ground attack missions. So if one of the locations is being used for a gun port, the gun could be replaced by lasers at a later point in time.
This is relative to the flight combat characteristics of the J-20; i.e, Latenlazy's proposition is that the high supersonic agility is very useful for dodging missiles. My proposition is that it's more useful for strategic mobility and hit and run attacks.
@latenlazy
Ever seen an EM chart? At Mach 1.2, 9 G of acceleration is half the angular change of Mach 0.6 9 G. You're arguing that twice the speed and a quarter of the agility (in angular terms, and I'd rather see half the agility with TVC) provides the same difficulty in interception as half the speed but twice the agility. You can work this out in your head; use two circles with radius 2 being 1/2 that of radius 1. Then cut two circular segments; the first circular segment has an angle half that of the second circular segment. The chord length between radii should be the same.
Using agility to dodge missiles (i.e, a last ditch effort) is best done at low speeds, because drag is lower and loss of energy can be quickly recovered.
@siegecrossbow
A future laser defense pod could be paired; and a good laser system with 4km or so of range would completely outmode a gun except in ground attack missions. So if one of the locations is being used for a gun port, the gun could be replaced by lasers at a later point in time.
why can't they just use missiles?
You're basically saying that you're more likely to dodge a missile traveling between mach 2 or 3 starting your maneuver at 400 knots than at 800 knots. This is nonsensical. If you're trying to dodge an SRAAM it's much better to start at mach 1.2, spend that energy budget in a tight turn that slows you down into mach 0.6, than it is to start at mach 0.6 and then try to maximize your corner radius, or accelerate into mach 1.2.
Similarly, though offensive maneuvers to acquire a lock involve more complex considerations, it's far better to start your maneuvers at mach 1.2 when you have much more energy that you can then spend in order to get into a firing position than to start at mach 0.6 to maximize your turn rate. You're only thinking in terms of transient performance as a static parameter, not in terms of the fighter's overall energy budget. It's always better to start with a higher energy budget.
This also applies to acceleration. If you're at mach 1.2, acceleration into a higher speed is of course more costly, but you're overlooking that at mach 1.2 you're already at the energy state that you're trying to reach when you're trying to accelerate from mach 0.6, and at the end of the day the whole point of accelerating is to reach that higher energy state. The missile doesn't care if you're accelerating faster or turning tighter if it's got higher relative speed than you. If your relative speed to the missile is higher your odds are always going to be better than if it's lower. That's what "bleeding energy" and "being a sitting duck" refers to. If you start your evasive maneuver traveling faster and thus being further from the missile when its launched your odds of surviving are going to be better if you start evasive maneuvering slower and closer. Higher altitude and higher speed is by definition higher energy. At those higher energy states you may bleed energy faster, but you also have more energy to bleed, and you get more out of the energy you spend.
Furthermore, an airframe that is capable of supercruise is by physical definition going to have a lower drag profile compared to a non-supercruising airframe accelerating from the same starting velocity, and may even maintain a comparable or superior drag profile accelerating from a much higher starting velocity. There is no part of this comparison where a supercruise capable airframe does not maintain a significant energy advantage over a non-supercruise airframe when it comes to kinematic characteristics.
Energy maneuverability is not just a static turn radius game. Angular and linear vectors, transient kinematics, and relative energy states all matter.
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This reminds me of the following photo, except it is on the other side. The smoke is above the edge of the fuselage suggesting that the gun port is on the shoulder close to the center and behind the canopy which matches the location (on the other side) in your photo. Maybe they decided to relocate the gun for some reason.
Edit: I must say that the newly found hatch seems unnecessarily too big for a gun though.
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I think maybe we're making a big deal out of what amounts to some basic changes in RAM surface treatment...
I doubt this hatch is for the gun because it is right above the air duct (even it curves inwards) and just behind the canard axis, there is no room to bury a gun. The hatch is also unnecessarily too large to a gun.
Could be. But unless the photo that I found (I can not trace it back now unfortunately) is a fake, J-20 should have its gun at the place of that hatch in 2022.
I agree about the gun position fwiw. Think we've both highlighted that same panel on the port shoulder before.
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