Issues on Intercepting Hypersonic Missile.

"RAM calculated by itself within milliseconds? ----now that's a bit carried away. You are assuming a full set of computer on the small SeaRAM to do the mathmatical calculation. and then able readjust your fly pattern. Didn't man overbored says SeaRAm cannot adjust speed and direction. For CIWS 's its reaction is 6 seconds, S-300 20 seconds. from getting data to calculation prediction to launching missile.
where on earth you getting SeaRAM calculated for a firing solution within miliseconds? definitely give me some references and link pls."

RAM flies to it's target using proportional navigation. Ring lazer gyros provide the attitude reference necessary for the seeker since the missle body is rolling in flight, just like Stinger and it's predecessor Redeye. You can find lots of good explanations of proportional navigation on line, just look around. RAM and all the other similar IR missiles using proportional navigation are analog systems. Their guidance systems make continuous rather than discrete course corrections. It does this by maintaining a constant angularity between the gyro mounted optics that hold the seeker element and the target. If as the open source literature maintains that RAM shares the more complex seeker from Stinger, which makes sense since it has to pick it's target out of surface clutter. Imaging IR missiles, those with a staring planar array such as AIM-9X and Python 5 among others have on board computers that are unbelievably powerful. They actually memorize the pixel shape of the object the pilot locks on and ignor countermeasures.
One point I agree with, making hard turns with these fast missiles is difficult. The materials used on the steerable surfaces, whether a canard or rear wing, are very special. Aluminum and most steels would just fold flat on the first turn! Companies have literally gone bankrupt trying to make missile canards to US Navy specs.
Solid fuel rockets are more than sufficient to accelerate to and sustain a missile at overt Mach 5. Phoenix exceeded mach 5. It was a very big missile too.
Something I have to remind all of you, these intercepts are over in two or three seconds. Most anti-aircraft missiles have a flight time measured in less than ten seconds, and things like IR missiles that can only "see" out to maybe ten miles have at most a two to three second flight time. There isn't anything resembling a dog fight between the missile and RAM, it is over in a blink.

Read down in this link to the paragraph labeled "Description" which talks about the seeker.



It's amazing the stuff you sign papers not to discuss, only to see the exact material in open sources! Now, dig this....



Amazing what one finds on the internet today. That is a modern IR guidance section.

crobato said:

It can but can it identify them as bullets?

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By process of elimination, build a IR profile of the missile, bullets and put in the system. and the bullet profile should look different.
so when it encounter a stream of bullets coming toward it at least knows they are not missile, got to be one of the two.

but the thing is whether missile or bullets, the evasive action is the same;acceleration at nonconstant rate.

man overbored said:

"Something I have to remind all of you, these intercepts are over in two or three seconds. Most anti-aircraft missiles have a flight time measured in less than ten seconds, and things like IR missiles that can only "see" out to maybe ten miles have at most a two to three second flight time. There isn't anything resembling a dog fight between the missile and RAM, it is over in a blink.

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what over in 2 or 3 seconds? let's say your missile traveling at 1km/s. so your engage distance is only 2 to 3km. that's CIWS range. So which one you like to use? RAM or CIWS? or both.

If the target missile seeing this RAM is coming in, it will accelerate at non-constant rate , then the RAM will have to make all kind of hard airo-dynamic adjustment in midair. who knows, maybe will break its back by doing so.

anyway, the RAM is as good as what it predicts, but non-constant acceleration by target makes it very tough to predict. who knows? maybe the RAM will predict wrong.

Here's a quote from your reading.

They process the IR energy received from the target in the 4.1 to 4.4 µm wavelength region to determine its relative angle and then, by using a proportional navigation guidance technique, continually predict an intercept point.

anyway, maybe we have to find out if there's good algorithm to predict a object's next position when its varying the rate of speed increase. that's 2nd order derivative and its nonconstant.

I also read some of the russiam antiship missile preprogrammed so the missile would follow a very eratic path, zigzag , roll up and down during its terminal phase. make it very hard to predict. what's US's solution to that.

lilzz said:

what over in 2 or 3 seconds? let's say your missile traveling at 1km/s. so your engage distance is only 2 to 3km. that's CIWS range. So which one you like to use? RAM or CIWS? or both.

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If have to take into account the speed of the incoming AShM also, let's say travaling at M2.5, it will close with the RAM at around 1,5km/s, that means a 5km distance is covered in 3,2... seconds.

If the target missile seeing this RAM is coming in, it will accelerate at non-constant rate , then the RAM will have to make all kind of hard airo-dynamic adjustment in midair. who knows, maybe will break its back by doing so.

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I don't understand why you keep mentioning the acceleration. If a car is straight in front of you and comes directly at you at 50 km/h, you'd have to shoot straight ahead to hit it. If it accelerates to 100km/h, you'd have to shoot in exactly the same direction. No need to calculate anything. (Exacpt for the distance, wich is a non issue in the RAM case, since the missile is not completely ballistic compared to gun bullets.)
And since the AShM is much heavier it's also more likely to breake due to the G-forces in evasive maneouvers.

anyway, the RAM is as good as what it predicts, but non-constant acceleration by target makes it very tough to predict. who knows? maybe the RAM will predict wrong.

Here's a quote from your reading.

They process the IR energy received from the target in the 4.1 to 4.4 µm wavelength region to determine its relative angle and then, by using a proportional navigation guidance technique, continually predict an intercept point.

I also read some of the russiam antiship missile preprogrammed so the missile would follow a very eratic path, zigzag , roll up and down during its terminal phase. make it very hard to predict. what's US's solution to that.

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AAMs can hit maneouvering targerts for decades now. In a missile to missile engagement, the priciple is the same. It has only become faster. But processors have also improved a lot over time you know.
It's not as if those CIWS / RAM are death proof. But they are far from helpless either.

I like to expand alittle more on the reaction time . Yeah, if you have onboard processor which is operating at Mhz range therefore you able to calculate thousands of instructions per second. No doubt it should able compute numerous new interceptiond points in one second.


However, how many times can it move its canard mechanically adjust to the new solution in one second. Probably only once in one second.

Therefore the bottleneck is how fast the canard can move. not the processor and sensor.
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Also, some folks doubt target missile can accelerate in 1 second,
well, consider this, I consider the engine stage is like a multistage pipeline.
missile already activate this series pipeline a few seconds ahead, so everything got filled up except the final output stage.

So, what you see "accelerate in 1 second" is actually the visual output of the final stage. but in reality what you don't see is the internal stages being filled up and primed. in actually it "start accelerate in 4 second" but seeing "start accelerate in 1 second".

Scratch said:

I don't understand why you keep mentioning the acceleration. If a car is straight in front of you and comes directly at you at 50 km/h, you'd have to shoot straight ahead to hit it. If it accelerates to 100km/h, you'd have to shoot in exactly the same direction. No need to calculate anything.

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It's more like sideway, not straight in front of. Space is three dimensional[x,y,z]

That's unrealistic to ask the interceptor to be dead in sync with interceptor
same y, same z, but only need to worry about the varying x.

Do you think that's possible?? [varying x, same y, same z]

A more realistic scenario is I am driving down in the freeway 100mile per hour.
and you hiding on the side and then drive your car and try ram and ambush me on the side. Not only 100mile at current speed, but I see you coming from side then accelerate on top of that.

you probably wishing you are coming from the same freeway but from opposite way.

Your ship is sitting in the ocean, and target missile can come from any angle, attiude and direction.

lilzz said:

A more realistic scenario is I am driving down in the freeway 100mile per hour.
and you hiding on the side and then drive your car and try ram and ambush me on the side.

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That's exactly the point where I disagree. If you in your car are the AShM, and I on the side am the RAM in the launcher, that means that I also mark the position of the ship, since the launcher is obviously placed on the ship.
Now, if you bypass me, that also means you bypass the ship and don't threaten it at all. Because if you want to hit the ship, you must fly towards it, and since the launcher is on the ship, it means the missiles must also fly towards the CIWS launcher .
That's what was already stated earlier in the thread when it was said there's hardly any latteral movement.
And it doesn't make any difference from wich direction the missiles comes, it must always head for the ship, and therefore also to the launching CIWS.

man overbored said:

These are high fidelity simulations of major threat systems. In actual practive RAM nails over 95% of these fast movers on the first engagement.

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This is pure exaggeration. It's only true when the anti-ship missile does not maneuver in terminal flight.

An incoming anti-ship missile is not flying in a predictable pattern. It will corkscrew and weave while still heading toward the ship. At mach 3, these maneuvers create a huge window of possible vectors it can take.

A missile with very poor maneuverability like the SeaRAM would find that a slight "jitter" in the anti-ship missile's vector suddenly takes it out of the SeaRAM's engagement envelope since the missile is 100 meters away from where it was expected!

A CIWS has about 1 second to engage a mach 3 anti-ship missile, there is simply no time to "move" your targeting to hit the missile. It's not like the missile is just going to wait suspended in the sky! If your first burst of bullets fail to accurately lead the missile, it will make a big hole in the side of the ship.

And even if a bullet hits the missile at the last minute, it's still far too late since the momentum of the missile will still definitely still tear a big hole in the side of the ship.

Scratch said:

That's exactly the point where I disagree. If you in your car are the AShM, and I on the side am the RAM in the launcher, that means that I also mark the position of the ship, since the launcher is obviously placed on the ship..

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Isn't your launcher is fix location ? If my missile coming from behind , do you mean moving your launcher and launch in the behind.

how you guarantee your missile in direct staring of of the target missile?

consider this I am running toward a house in arbitary direction, and you come out from a house to intercept me. how you guarantee you get to spot and see me dead on eye and eye and run opposite of me, and we butt heads. Isn't it more logically you come from side try to ram me down sideway.

If your coming towards a house where I'm coming out, we naturally close in "head on". Running at M2, you can't just make a 90° turn putting the target on your three or nine o'clock position, run a quarter circle around it and turn back after you eveded a missile, when you're only few seconds out.
And it doesn't really make a difference if the launcher is 50 in one or the other diretion on the ship, it's still rather head on.