Behind the China Missile Hype

s002wjh said:

the missile head is not gonna made with glass type material. i don't think any ballistic missile has a glass type nose in front for good reason, i could be wrong. also vibration, g-force is not an ideal environment for puting LN2 in a enclosed cone. the LN2 will evaporate into a gas form upon contact with heat. IR will have the same issue as RF, which is how to ID the carrier vs other ships, the algorithms gotta be pretty advanced to do that.

either way its better to use RF active seeker than IR, RF usually has further range/better resolution compare to IR, active emitter with frequency hopping, pulse modulation, pulse on pulse technique are diffcult to jam.

Click to expand...

Come one guys.

You don't have to put the sensor in the NOSE tip

i.e. said:

Come one guys.

You don't have to put the sensor in the NOSE tip

Click to expand...

where do you suggest to put it, at the rear you need direct line of sight for sensor to work properly. hence the sensor or radar is put in front of jets, same with missiles. missile/fighter jet is not an awac, aerodynamic is a critical factor.

s002wjh said:

where do you suggest to put it, at the rear you need direct line of sight for sensor to work properly. hence the sensor or radar is put in front of jets, same with missiles. missile/fighter jet is not an awac, aerodynamic is a critical factor.

Click to expand...

may be on the side with a pop-out extension.

you can also have a aerospike extension in front of the nose to tailor your shock wave to achieve certain desirous flow fields on the local flow on your nose cone...

for example: lower drag.

for another example: keep shock away.

for another example: keep nose cool.

There is all kinds of aerodynamics tricks one can play. nothing says the vehicle has to be an abllative blunt body.


===

because i am in such a good mood today.

here



you will find the particulars of how to design an aerodynamic doom for optical window. include the "spike option".

,

here is a paper that talks about spike. notice the nose is optical doom.




patent

i.e. said:

may be on the side with a pop-out extension.

you can also have a aerospike extension in front of the nose to tailor your shock wave to achieve certain desirous flow fields on the local flow on your nose cone...

for example: lower drag.

for another example: keep shock away.

for another example: keep nose cool.

There is all kinds of aerodynamics tricks one can play. nothing says the vehicle has to be an abllative blunt body.


===

because i am in such a good mood today.

here

Please, Log in or Register to view URLs content!

you will find the particulars of how to design an aerodynamic doom for optical window. include the "spike option".

,

here is a paper that talks about spike. notice the nose is optical doom.

Please, Log in or Register to view URLs content!

patent

Please, Log in or Register to view URLs content!

Click to expand...

base on chinas military stuff, they tend to put proven design on their stuff.
china certainlly don't want add something that hasn't proven as another unknown factor into a the design. so what happen when they add an IR but find out the spike oesn't work as they expected. active RF is best route for them.

also the spike is meant for reduce SOME pressure/temperture at the nose, not for IR purpose but to increase maneuverability and less damage to the nose, whether is enough for IR is another issues, which require more R&D. the heat radiation from carrier deck is only few degree above ambient temperture, is the spike enough to reduce teh pressure/tempture lower than or same as ambient, probably not.

so far i haven't seen a hypersonic ballistic missile with IR sesnors yet, i could be wrong. if you find one let me know.
if IR is superior than RF, and the spike can eliminate the pressure/temperture of the nose, we at least should see some development or existing ballistic/hypersonic missile with IR sensor.

s002wjh said:

well for IR to work properly the radiation has to be lower than its target/ambient temperture, which when the missile is travelling much higher than the speed of sound which make it impossible. due to fraction of air, and enclosure compartment. its not only the IR sensor generate heat, but also other system in the missile. and those heat has to dissipate/aborb somehow.

i'm assuming AsBM gonna hit high value targets, carrier, in that case it needs ID the ship and track it, the ID part require more sophiscate algorithm in the real time processor, thus the performance processor has to be top notch to do real time.

Click to expand...

Yes there were issues, but engineers are not stupid, if there is a problem there is a solution.

But IR does not need to track infrared radiation sources, you can track the shadows. For all intent and purposes we know that a large ship have a very different thermal signature than the surrounding water. The main issue is the IR receiver lens heating up; but this is controlled by 1) coolant bottles (liquid nitrogen or equivalent) and 2) physical filtering and 3)electronic filtering.

You only need a enough coolant to cool the sensor when the missile have broken into the atmosphere for final target aquirsition - so you do not need alot of coolant.

So physical filtering is not that hard or complicated, heat mirrors are commercially available in photography and lab equipment.

Signal processing is not hard as well - FFT and RMS have been developed into real time digitial filters; which could effectively filter out a specific spectrum of IR temperature which lets say the cone is at.

All the technology required are here to make it happen

Lezt said:

Yes there were issues, but engineers are not stupid, if there is a problem there is a solution.

But IR does not need to track infrared radiation sources, you can track the shadows. For all intent and purposes we know that a large ship have a very different thermal signature than the surrounding water. The main issue is the IR receiver lens heating up; but this is controlled by 1) coolant bottles (liquid nitrogen or equivalent) and 2) physical filtering and 3)electronic filtering.

You only need a enough coolant to cool the sensor when the missile have broken into the atmosphere for final target aquirsition - so you do not need alot of coolant.

So physical filtering is not that hard or complicated, heat mirrors are commercially available in photography and lab equipment.

Signal processing is not hard as well - FFT and RMS have been developed into real time digitial filters; which could effectively filter out a specific spectrum of IR temperature which lets say the cone is at.

All the technology required are here to make it happen

Click to expand...

and as i mention before LN2 is not an ideal to put it in a ballistic missile for multiple reason, see my previous post. also its not just the heat from lens, the outside temperture infront/surround the missile is also increasing, and you can't cool that.

and its not about DSP its about sensor. the dsp can filter out certain frequency if sensor can detect multiple source, but when missile fly at hypersonic speed, the only thing sensor will see is the heat radiation from fraction, other source. basicaly your Noise is larger than you Signal.

it doesn't matter how many IR filter or DSP fiter you put into the system, the noise > the signal you try to detect. for IR to work the background radiation/noise HAS to be lesser than the carrier IR signal.

the glass type lens can't withstand the temperture during re-entry either is another reason you can't use IR.

the engineer will use alternative method to solve some issue if the problem is too diffcult. "if there is a problem then there is a solution" depend how diffcult the problem is, sometime its not worth it to pursue or impossible to solve with current technology.

there are too many issues need to be solve in order to use IR. its better/efficent to use RF, and put more resource on devloping algorithm and other stuff rather than try to figure out how to reduce IR noise, and develope a glass dome lens that can withstand re-entry temperture.

You might well use water to cool the skin of your warhead, then exhaust the steam near the front and so keep air that is too hot away from your warhead skin. Use sapphire rather than glass for your window. Cool what must be cooled deep with LN2 and exhaust your gaseous nitrogen over your window.

delft said:

You might well use water to cool the skin of your warhead, then exhaust the steam near the front and so keep air that is too hot away from your warhead skin. Use sapphire rather than glass for your window. Cool what must be cooled deep with LN2 and exhaust your gaseous nitrogen over your window.

Click to expand...

like i said for all those trouble, might as well just put a RF sensor in there, and be done with it. no LN2, or water, no glass dome etc etc. to solve the IR issues, require quite a bit research & test, at the end it might not be possible or no significant benefit compare to RF.

It makes sense to use sensors for different wavelengths to improve discrimination between different possible targets. Not spending money for this purpose doesn't make sense.

delft said:

It makes sense to use sensors for different wavelengths to improve discrimination between different possible targets. Not spending money for this purpose doesn't make sense.

Click to expand...

yes it make sense for redundancy, but at some point the price, time, diffculty become issues. most missile only need one sensor, put more than one increase the cost, time, integration etc. espeically for ballistic missle and IR, would pla favor use both RF and IR, spend alot time/cash try to fix the issue associate with IR on ballistic missile or is it better to use that resource for better algorithm development, better rf sensor, and testing etc etc. why spend so much time/cash to put another detection sensor that basically has the same purpose as teh RF sensor. in any project, the PM has to consider the cost, time, resource management etc, RF is the better choice.