It's only taken it's first flight and look at what Winnie the Xi's propaganda machine is already producing.
It doesn't even make sense. Hypersonic missiles are good at being hard to take down themselves. But you don't need that to take down an aircraft. You need super sensitive radar systems, since the claim is that these aircraft reflect about as much energy as a bumblebee would.
Do note that the this claim comes from the same people who don't hand out any actual specs and always fly with an additional reflector. The latter makes it easy for radars to see them again. This is helpful in allied airspace, but it also makes it impossible to verify the claim.
Also note that modern radars are sensitive to how fast an object approaches (or leaves) the radar. Bumblebees don't break the soundbarrier usually, so it is possible to see these planes, but you do have to tweak your radar for it. (Hence why the US doesn't give specs.)
Also note that modern radars are sensitive to how fast an object approaches (or leaves) the radar. Bumblebees don’t break the soundbarrier usually, so it is possible to see these planes, but you do have to tweak your radar for it. (Hence why the US doesn’t give specs.)
You are talking about Doppler processing. Basically you can filter out all the things that are not moving fast based on how much the frequency is compressed and lower your noise floor. You will still have other noise sources but minimizing clutter will help, if the return is below other noise sources you still will not be able to detect it.
Correct. But integrating over multiple pulses, and using the latest Tx and Rx modules, sensitivity is not the problem anymore. Radars can easily see every damn bumblebee in a 100km radius. The problem is filtering data, so that processing and/or the user is not overloaded. For example, if you track every single bird with a radar that has a 100km radius, you will not be able to see anything on the operator screen other than birds.
Doppler is easy to filter on early in the processing stage. Meaning that if you can detect the aircraft, you can still separate it from all other bumblee like objects. Clutter tends not to move that fast.
Doppler processing eliminates clutter it doesn't eliminate EMI, thermal noise, or atmospheric issues.
China's 366 radar can detect 0.1 sq meter targets at 20km. It's China's most modern radar and it's not close to 100km detection range for LO aircraft.
Play around with the radar range equation.
For a 100km detection range.
1 MW of output power, 30 dB antenna gain, 1Ghz Tx frequency, radar cross sectional area 0.1 m sq, minimum detection signal 0.005 nano watts.
On low power systems where you can have much lower internal emi, -100 dB (0.1 nano watts) is as low as you can get outdoors.
So they just need to build an aircraft that moves at the same speed and height as a bumblebee. Bam ! Undetectable killing machine.
You'd be surprised the velocity you get from the return on a bird's flapping wing. Also the Doppler ambiguity smears with SNR, so you'll see a bird as something moving between 30 and 300mph at the edge of sensitivity.
Radar is echolocation with EM waves (low frequency light) instead of sound waves. And there are already plenty of radar guided missiles.
That is called passive sonar. I suspect that it is kinda hard to hear from the missile. Anything behind you is certainly not hearable, since the missile goes faster than sound. I have no idea if you could measure the sound coming from the front. You also have to take into account that you are chasing an after image, since the plane is also faster than sound. But torpedoes use this, so the idea is valid.
Those are likely quite valid points. This being noncredible defense they have no place here.
It’s not that impressive… a bumblebee can emit the same small radar signature as well.
Hypersonically it goes door-to-door knocking
"Any B-21's here? No, right then. On to the neighbors."
The article I read indicates China used a sim which means they have to guess at what the RCS of the b21 is. Further they shot down the simulated b21 with a hypersonic missile after they pretended to target something else then veered towards the b21, claiming the pilot wouldn't take evasive action based on it's initial trajectory.
So if China knows the RCS of the b21, the performance, and the pilot doesn't react to a missile targeting the b21, they can shoot it down.
This is the equivalent of someone telling you exactly which Bullshido moves they would use if they were attacked by a professional MMA fighter.
In a simulation where the only radar reflector is one simulated jet, and there is no real hardware, it's pretty easy to hit since the Pfa is effectively zero. In the real world, there's a thousand different things which will give some similar energy return and there's no simple way to filter that out without actually seeing the thing in real life.
Stealth isn't about zeroing the energy, it's about pushing it into an ambiguous state space where it cannot be distinguished from birds and shit.
Doppler filtering will do alot to eliminate slow moving clutter sources but I have my doubts they can detect a 0.1 sq meter return much further than 20km.
Stealth uses many techniques to lower the return, shaping to stop direct returns to the source, mag ram (magnetic radar absorbing material) to absorb some of the energy and stop traveling waves at high frequency, and resistive cards or similar methods for low frequency which has sections of different resistivity that cause mini defractions instead of one large one.
I worked on the b-2 (has the same tech nearly). If you take a panel off to inspect anything or fix an issue the jet has to go to the paint shop to have the paint re-applied because its most of what makes it stealth. The paint absorbs radar.
The most bat shit insane part of this is the missile absolutely cannot maneuver to intercept at hyper sonic speeds unless it's a nuclear warhead. In which case, yes we know you can down a plane with a nuke.