This is what the F-22 can do

[GGTharos]

80nm, vs. what? A fusion reactor?

 

 

Kinda like saying AMRAAM's range is 40nm ;)

 

Claims of IR systems picking up targets this far are -quite- exaggerated when it comes to the typical BVR scenario.

 

Maybe look-up against a MiG-25/31 or SR-71 with the pedal to the metal ...

[Weta43]

That anti missile system aboard a 747 in development by the US at the moment that Pilotasso mentioned has a laser scanning, tracking & ranging system to follow battle field ballistic missiles & allow targeting of the main laser weapon system.

Having been cued to the initial launch area by wide angle IR detectors (a job presumably done by EWR for a fighter system) they plan to be able to use LIDAR to track & range missile sized targets at up to 300km with enough accuracy to be able to target the missile with the laser weapon.

The system is bulky, but the bulk of the system is given over to the fuel cells & generators for the 5MW 'killer' laser.

It's still a long way off being put in fighters, but the US millitary presently believes LIDAR will work at ranges out to 300km (including lookdown).

 

EDIT - of course it will actually work to any distance - they range find the moon using LIDAR, but 300km through the atmosphere is considered do-able at the moment

[GGTharos]

And we are comparing the ability to detect a rocket motor to a head-on fighter because ... ?

A rocket motor radiates energy like -crazy- in all directions. It is -nothing- like a head-on fighter.

[GGTharos]

They'll likely be flying /above/ all that, and shooting up into space. ;)

[Weta43]

‘And we are comparing the ability to detect a rocket motor to a head-on fighter because ... ?

A rocket motor radiates energy like -crazy- in all directions. It is -nothing- like a head-on fighter.’

 

Actually we’re not.

Their plan is to rely on the booster bloom to provide the initial cue as to where to look, but then use LIDAR to range & track the missile actively. This will not depend on radiated energy at all. - & a missile front on must be about the same size as a small fighter…

 

‘They'll likely be flying /above/ all that, and shooting up into space.’

 

Their stated intention is to destroy the missile immediately after launch - well before it leaves the atmosphere.

 

‘Wouldn't the ability to look down/shoot down be important in case they were engaging multiple targets and one slipped by from high to low?’

 

Yes – their plan it to use it look down, shoot down (no pun intended :-) at up to 300km range.

[Weta43]

300km is the range they've quoted - & they plan to fly above the weather, but I guess 300km is still optimal range from above the weather then down through it at a steep angle. Still - if they got it to fighter sized units that meant you had to sit somewhere near your service ceiling & on a clear day could track out to 150km from there – that’s still pretty handy

[GGTharos]

'Well before it leaves the atmosphere' is ... um. Well, the Atmosphere is about 120km worth of altitude - you have some time to detect, track and shoot.

 

But you won't be shooting at it until it has climbled a good deal, specifically because you -have- to do the whole detect, track, aim and fire thing.

 

And they're not shooting missiles head on. They're shooting side-on, and yes, it depends on radiated energy for detection. That's your first clue that the missile has been launched, as you said, the cue for the LIDAR to acquire.

 

At 300km, that missile's going to have to climb before it's even detectable, unless I recall my earth horizon diagram wrong (entirely possible)

[Weta43]

Their method of destruction is to heat the missile skin till it loses structural integrity & let the resistance of the atmoshere crush the missile as it climbs - I guess you have to do this while there's still enough gas present in the atmoshere to do the job...

 

Regarding the use of booster bloom to cue the LIDAR. True - that option wouldn't be available against a fighter, but EWR would & could provide the same role. Also the timeframes against a plane aren't quite so tight.

 

I don't know what distance the horizon is when at the ceiling for a modern fighter either, but whatever limitations there are on line of sight for a missile are the same as they are on a plane. If a plane at 300km NOE is below the horizon at the hight you're flying, it's below the radar horizon as well. If when a missile is high enough to be above the horizon & be seen it is high enough for atmosphere to not be a big problem to the LIDAR, presumably the same is true of a plane.

[GGTharos]

Their method of destruction is to heat the missile skin till it loses structural integrity & let the resistance of the atmoshere crush the missile as it climbs - I guess you have to do this while there's still enough gas present in the atmoshere to do the job...

Thought missile's acceleration alone could do that ...

 

Regarding the use of booster bloom to cue the LIDAR. True - that option wouldn't be available against a fighter, but EWR would & could provide the same role. Also the timeframes against a plane aren't quite so tight.

Nope ... a stealth aircraft is still stealth - even EWR -will- have issues with it. Furthermore, most of the EWRs that really -can- pull this off, IIRC, don't even feature that level of datalink. They're more on the strategic side.

You've got an IR sensor looking for an aircraft which is also stealthed against IR.

Furthermore, the radiation from such an aircraft is rather conservative head-on, you've got a relatively small emitting surface, and a relatively cool temperature - and attenuation inbetween.

 

I don't know what distance the horizon is when at the ceiling for a modern fighter either, but whatever limitations there are on line of sight for a missile are the same as they are on a plane. If a plane at 300km NOE is below the horizon at the hight you're flying, it's below the radar horizon as well. If when a missile is high enough to be above the horizon & be seen it is high enough for atmosphere to not be a big problem to the LIDAR, presumably the same is true of a plane.

What is -not- true, however, is that you'll be able to pick it up ;)

I don't know what frequencies LIDAR operates on - it -may- be able to go through vapor depending on the frequency of light being used.

[Weta43]

Just had one of those Doh! Moments..

You could actually just throw all this gear in with an appropriate search radar on the AWACs well before it’s fighter sized (though each fighter having it’s own gear would be better).

The AWAC knows exactly where it is, can very accurately define where the target it’s tracking is with LIDAR (from say 200 – 300 km away) & feed that to the fighters over a datalink & they could fire without ever turning on their sensors on. Don’t the F-22 already have the ability to launch & provide mid course correction to slammers using target positions datalinked to them by another plane?

[GGTharos]

Yes, in fact, most modern fighters have that capability.

 

Now, can you think of any reason why your proposed IR system isn't even being -evaluated- for such use?

 

 

Even against land targets JSTARS uses radar. LIDAR is still far, -far- from being implemented on any combat aircraft. They've only got a few proofs of concept flying right now, if that.

[Weta43]

"The ABL is designed to detect and destroy theatre ballistic missiles in the powered boost phase of flight immediately after missile launch."

 

I was under the impression that longer wavelength EWR could detect 'stealthy' planes, just not provide accurate enough position data for weapon engagement. In this case all they would need to do is define a relatively small area for the LIDAR to actively search (perhaps within a kilometre or so). At this point whether the plane has been designed to reduce it’s IR emissions or not is irrelevant, you’re using LIDAR not passive IR sensors. (you could perhaps paint the plane in a coating that absorbs a wide band of the spectrum – make it very black – but have you ever noticed what happens to black cars on a sunny day – they get very hot – precisely because they absorb radiation.)

EWR have not traditionally been datalinked to this level – but there hasn’t traditionally been a need for it. Perhaps there is now…

 

‘What is -not- true, however, is that you'll be able to pick it up’ – Personally – I don’t see any objections you’ve raised that convince me.

"The ABL is designed to detect and destroy theatre ballistic missiles in the powered boost phase of flight immediately after missile launch."

 

I was under the impression that longer wavelength EWR could detect 'stealthy' planes, just not provide accurate enough position data for weapon engagement. In this case all they would need to do is define a relatively small area for the LIDAR to actively search (perhaps within a kilometre or so). At this point whether the plane has been designed to reduce it’s IR emissions or not is irrelevant, you’re using LIDAR not passive IR sensors. (you could perhaps paint the plane in a coating that absorbs a wide band of the spectrum – make it very black – but have you ever noticed what happens to black cars on a sunny day – they get very hot – precisely because they absorb radiation.)

EWR have not traditionally been datalinked to this level – but there hasn’t traditionally been a need for it. Perhaps there is now…

 

‘What is -not- true, however, is that you'll be able to pick it up’ – Personally – I don’t see any objections you’ve raised that convince me.

[Weta43]

'Now, can you think of any reason why your proposed IR system isn't even being -evaluated- for such use?'

 

Some -

 

Perhaps because it's still being developed by the US under funding tagged for the Star Wars projects, & perhaps because no-one else in the world is close to having something you'd need to use it against, while a number of countries have ballistic missiles, & perhaps because the two tasks are so similar that it's not necessary to run two separate R&D programmes?

[GGTharos]

Lidar has no military application at this point beyond making maps - and do keep in mind that 'LIDAR' applies to your average cop's laser gun ;)

 

As for EWR's: Yes. The longer wavelength DOES make them better able to pick up stealth aircraft, but steralth still -does- work. I should have been more clear. EWR's range is also reduced, but not to the same degree.

 

Now, to stealth against LIDAR: All you have to do is polish the surface up, actually, or at least create a suitable diffraction grating. May actually be easier than radar stealth and you might be able to build something that would phase the lidar pulse out actually, but I don't really think so ;)

[Weta43]

'Lidar has no military application at this point beyond making maps'

- making maps and the IRST sytems already in use in fighters ('Infra-red search and track systems often incorporate laser range-finders in order to provide full fire-control solutions for cannon fire or launching missiles.') Laser rangefinders are lidars.

 

'and do keep in mind that 'LIDAR' applies to your average cop's laser gun '

Yes - it's very versatile & easily adaptable technology.

 

'Now, to stealth against LIDAR: All you have to do is ...'

Make it invisible.

[GGTharos]

Nope. Mirror it up. Stealth against lidar may in fact be potentially easier than against radar (but then again, might be much harder)

 

Yes, you're right, laser rangefinders are lidars. What they're not is search and track devices - they need something else to cue them, and are currently not particularely long-ranged.

[Weta43]

‘Nope. Mirror it up. Stealth against lidar may in fact be potentially easier than against radar (but then again, might be much harder)’

 

You could mirror it up –though it would probably become a mirror at all frequencies including radar - & the thing is that if you do get a reflection from a mirror – even a little one – it’s very strong. You also have 2 other problems in that:

1/ that even if you don’t see the reflection it will be very evident to others. Imagine shining a spotlight on a mirror ball. Everybody in the room gets a good return. I guess that’s why present stealth relies on radar absorbing materials (black as far as radar is concerned) as well as proper shaping.

I suspect that the more of the Electro-Magnetic Radiation spectrum you try to make the object stealthy against, the more difficult it becomes to achieve. Effectively you’re trying to make it invisible right across the entire EMR spectrum from all directions, because if you’ve got 2 searchers looking for you separated by some hundreds of km horizontally & a few km vertically your mirrors are presenting quite different aspects to them (again with the mirror ball).

and 2/ Even if you completely remove its return in the direction of the search laser, you’re being cued from EWR where to look, & lookdown (& to a lesser extent lookup) the target becomes (because I can pick & design in a frequency from my laser to provide high contrast) a black object against a non black background to one searcher & a mirror ball with a light on it to others – easy to spot & range through triangulation. Either way, it’s technology further off than improved LIDAR.

 

 

’Yes, you're right, laser rangefinders are lidars. What they're not is search and track devices - they need something else to cue them, and are currently not particularely long-ranged.’

 

Both of which points I think we’ve gone over.

Remembering that of course they are search & track devices – the target moves about & they keep track of it so when it isn’t where it was a moment ago they search for it & keep tracking it. Given they don’t search as well as radar at the moment so yes you need something to cue them to the general area – AWAC or EWR would do – as we’ve discussed they can detect ‘stealthy’ aircraft – not to the range they can detect non-stealthy ones, but from a good distance BVR & not accurately enough to guide weapons to a hit, but well enough to tell something more accurate where to look. Then they're quite capable of search & track.

No - LIDAR don’t have very long range at the moment – but the ABL programme is specifically intended to increase that range (under proper conditions) to 300km.

[nscode]

Lidar has no military application at this point beyond making maps - and do keep in mind that 'LIDAR' applies to your average cop's laser gun ;)

Yup... and I'm about to make one this summer... if I get all the parts :)

 

 

And yes, there already are stealth devices against lidars for cars :)

[pho3nix]

So...what does X-band have to do with IR? They are separated by thousands of millimeters of wavelength.

 

I just put in X-band to try and get this topic back on to the F-22 interms of stealth preservation over detectors.

 

Think you can train the average aircraft maintainer to deal with fiber optics in only a few months? Think again.

 

This skill is more of an art than a science...well, actually its completely scientific, but not to the point where any average guy off the street can maintain it effectively.

I have had a think about it... for 3.5 years now and from a patch leed point of view, fibre optics is not much mode difficult to matain than wire. yes you have to keep it clean but that is a pocket-size kit away.

 

It takes YEARS of training and practice to get any good at it. One stray AAA round or piece of shrapnel from a SAM would render such a fiber-optics system useless for...well, probably the duration of most future wars. That is even ASSUMING you have qualified personnel to deal with it.

 

Iam sure that if an round or high velocity incident particle was to impinge on a wire with force enough to break a sheathed fibre, it would sever the wire also.

 

The reason I mentioned adaptive optics is that if the source subtends a very small angle & is distorted by the atmosphere it's image will be blurred across several pixels & may not fire any of them. If the image can be sharpened up then all the reflected or emitted energy from the target collected by the lens will land on a smaller number of pixels ( maybe 1 ) & the chances of the image being detected go up.

 

Good Point but there still may be simpler methods of correcting effective abberation rather than adaptive optics but it is definatey an avenue to reaserch

 

Darn :D Takes me too long to post if i'm learning physics at the same time... damn you Van der Waals :D

 

For two oscillating particals under coulombic interaction the attractive Van der Waals interaction varies as the inverse 6th power of the separation of the two oscillators;).

 

Its all in the hamiltonian:thumbup: and than on to the Madelung constant:P

 

True...but how are you going to get large enough numbers of those guys to take a pay cut by joining the military?

 

I will be getting a pay cut from $85000 au (first year out) in photonics to that value 10 years after joining the RAAF... or that may be because i love flying too much:pilotfly:

 

LIDAR is a very hot ticket right now in defence science and for thoise in the know... jump on it because technology is advancing rapidly:thumbup: even faster after my reaserch is finished:book::book::book::book::book::book::cry:

[tflash]

1/ that even if you don’t see the reflection it will be very evident to others. Imagine shining a spotlight on a mirror ball. Everybody in the room gets a good return. I guess that’s why present stealth relies on radar absorbing materials (black as far as radar is concerned) as well as proper shaping.

I suspect that the more of the Electro-Magnetic Radiation spectrum you try to make the object stealthy against, the more difficult it becomes to achieve. Effectively you’re trying to make it invisible right across the entire EMR spectrum from all directions, because if you’ve got 2 searchers looking for you separated by some hundreds of km horizontally & a few km vertically your mirrors are presenting quite different aspects to them (again with the mirror ball).

and 2/ Even if you completely remove its return in the direction of the search laser, you’re being cued from EWR where to look, & lookdown (& to a lesser extent lookup) the target becomes (because I can pick & design in a frequency from my laser to provide high contrast) a black object against a non black background to one searcher & a mirror ball with a light on it to others – easy to spot & range through triangulation. Either way, it’s technology further off than improved LIDAR.

 

It is not only diffraction, but also diffusion. It is not the case that everyone will get a good return. Due to the fact that you reflect in all directions, the reflection is much less intense. Even if you do not take into account absorption. You can not create energy out of nothing.

 

I agree, however, that the only true air defense against stealth is radar (or more generic, sensor) networks. dispersing receivers and transmitters and having central processing you could build a good EWR network that can detect stealth aircraft earlier I guess.

 

In weapons systems, you should always keep in mind good examples from nature.

 

Top notch predators like humans, sharks, orca's, feline and wolfen have:

 

- a good, focussed tracking sensor (humans use the Mk1 Eyeball so there is still some future in optics I guess :)

 

- intelligence: all build extreme SA

 

- communication: can be used to compensate for the rest. The big pro of the somewhat limited Mk1 equipped humans, but also orca's and wolfs exchange a lot of comms. Sharks might not be that talky but they sure have a mouthfull of arguments ready

 

- speed

 

Those at the other side, like deer, often rely on very good EWR sensors that do not enable tracking. When they hear a noise or spot a visual disturbance they just run. They are unable to track their assaillant and only rely on reaction and evasion speed. The only comms they need is very similar to classic EWR: they mostly issue warnings, but little or no usable coordinate info. Predators do communicate tracking info to each other to coordinate the attack.

 

I do not now how they reed it in fossiles, but Raptors BTW are considered to have razorsharp vision, remarkable intelligence, very evolved communication skills and of course blazing speed. Paleontoligist guess that communication abilities gave the raptor the edge over bigger competitors.

[Weta43]

'You can not create energy out of nothing.'

No – but you cannot destroy it either - which means if you have a fairly powerful laser shining on you, you either absorb it & turn it into heat or you change its direction & radiate it out again – which means somewhere you’re shining.

 

If the whole surface is covered in something that diffuses all the radiation falling on it out in all directions, then the whole surface shines dimly when lit - like satin finish chrome or matt white paint - & the total amount of energy returned will be relatively high.

My personal guess at the best finish would be something dead matt & mid grey (absorb some of the radiation falling on it, but not so much that it causes additional skin heating, disperse some more of it off the matt surface & rely on acute angle reflections to send some more on its way)- pretty much what the F-22 has now, (coincidence?) but the F-22 is pretty fair game to a search light (laser)

 

Much as I hate it when people use this line of argument – If all it takes to defeat a LIDAR system is a chrome job or a can of metalcote & a polishing cloth then 1/ The US government is going to look very silly when they deploy the ABL system & the members of the Axis of Evil defeat the system by chrome plating their missiles & 2/ why doesn’t the US (& for that matter all other air forces) paint all the backwards facing parts of their planes in laser defeating material to stop laser ranging weapon control systems (IRST) getting a lock ? Admittedly the back ends of most planes have some pretty LIDAR friendly facets, but a missile is inherently a fairly stealthy shape from anywhere but behind…

[nscode]

It was sayed that what you get from EWR (or any other long wavelenght radar) isn't precise enough to guide a missile to it. What about one with a nuclear head in it?

[Guest IguanaKing]

 

 

 

Iam sure that if an round or high velocity incident particle was to impinge on a wire with force enough to break a sheathed fibre, it would sever the wire also.

 

 

Absolutely correct, but that severed wire can be repaired quite quickly. Even an ARINC429 databus wire can get by with being buttspliced for a short run...and you can train a monkey to use a set of PIDG crimpers effectively and quickly. ;)

[GGTharos]

It was sayed that what you get from EWR (or any other long wavelenght radar) isn't precise enough to guide a missile to it. What about one with a nuclear head in it?

 

You -might- be able to do that, even with the largest of EWRs ... but then, that's an entirely different style warfare, and once you go there ...

[Guest IguanaKing]

Hmmm...which would be more dangerous to the population that SAM was protecting? [scratches chin] ;)