Stealth fighter vs stealth ship

[kirtap]

The amibition (in terms of RCS) of most 'stealth' ships are far far far lower than what is deemed stealthy on an aircraft. Most of them only do the bare-minimum, reducing the specular return from the superstructure, but little else.

[Sanem]

As pointed out by Belethor:
http://www.is.northropgrumman.com/pr...NI_datasht.pdf

IFF and all that won't help much when you're in a dogfight where allied aircraft without IFF's are present, or that IFF fails, that's why only F-15s with the most advanced sensors where allowed to fire beyond visual range over Iraq, which becomes a whole lot more difficult in a complex dogfight
not to mention the problems a dedicated enemy ECM will do to IFFs. or the Russian idea of using IFFs as targetting beacons.
electronic sensors also help little against enemy targets, who certainly won't give you their electronic signature codes in advance
so with both blue and red forces, (IR) visual detection is something the F-35 relies on heavily

here are images from the optical seeker on the Python 5, you'll see that the aircraft are easily recognisable even to human eyes:

...but with what field of view. As stated the Ikonos image was an 11km strip...this allowing for some semblance of area search...even then its not great. The point I'm making is that the stealth aircraft needs to search for the ship and it wont do so with the field of view even in the, relatively low res, ATFLIR image posted by moonlight.

the ability I mentioned is over 10 years old

here's an example from ARGUS-IS:


also we're talking here about something like an F-35 flying in at maximum range
but what is to keep something like an RQ-170 to close in guided by long range radar scans, sitting almost on top of the ship to get the best images, and uploading the high quality images via undetectable satellite link to a Pentagon supercomputer who'll have very little trouble identifying the images correctly. that gives you excellent undetectable, on site targetting information, at a fraction of the cost of an F-35, like your personal miniature satellite

We are presumably talking about today though.

yet most of this discussion centers on technology that is over a decade old (like LITENING) or won't be fielded until for at least 5 years (F-35, and no one's holding their breath on that one, except maybe the Marines with their 2014 IOC )

3 words. False. Alarm. Rate.

well maybe they should use those images as CAPTCHA tests?
"before you can access this top secret data, please link the image on the left to one of the ship blueprints on the right"

[seahawk]

IRST stand for infrared search and track so i think it can automatic serching as well , btw i haven't hear about optic sensor on fighter that use UV , can u show me some caused it sound quite strange

Not on a fighter yet afaik. There are other applications for UV sensors in the work, which I would rather not talk about. But the combination of normal imaging and IR for example is quite common already.

And surely an IRST can search but any optical sensor is limited by resolution, so you always have a trade-off between Field of view and range at which a target can be detected. Look up this commercial system: http://www.infraredcamerasinc.com/im...eries_2008.pdf

See the difference in FoV between the different lens options. So the longer your range (at which you get a useful picture from the sensor) the smaller your FoV is. So at maximum range, searching with an IRST is like watching the world through a straw.

The interesting point for this debate however is that using optical sensors in general giving an advantage to the ship, as it is able to carry more of those and heavier and larger and also has way more processing power (or should I say "should have") to process the images. Giving the qualities of current sensors I dare say that the advantage of looking up into the sky instead of down on to the ground (sea) is not that much of an advantage any more, but still it makes processing easier.

[moon_light]

Not on a fighter yet afaik. There are other applications for UV sensors in the work, which I would rather not talk about. But the combination of normal imaging and IR for example is quite common already.

And surely an IRST can search but any optical sensor is limited by resolution, so you always have a trade-off between Field of view and range at which a target can be detected. Look up this commercial system: http://www.infraredcamerasinc.com/im...eries_2008.pdf

See the difference in FoV between the different lens options. So the longer your range (at which you get a useful picture from the sensor) the smaller your FoV is. So at maximum range, searching with an IRST is like watching the world through a straw.

The interesting point for this debate however is that using optical sensors in general giving an advantage to the ship, as it is able to carry more of those and heavier and larger and also has way more processing power (or should I say "should have") to process the images. Giving the qualities of current sensors I dare say that the advantage of looking up into the sky instead of down on to the ground (sea) is not that much of an advantage any more, but still it makes processing easier.

how about the DAS , it have FoV of 360 degree so even at longest range the FOV may still be enough

[moon_light]

btw what the different between DAS and EOTS , and why dont they use long wave IRST on F-35 ? , isn't the technology already available in AAS-42

[SpudmanWP]

EODAS is a 360 MLD/MAWS that provides additional functionality. It is only meant to function in the WVR arena. There are 6 EODAS sensors on each F-35. EODAS cannot zoom except for digital.

EOTS is a combination FLIR/IRST and can function at much greater ranges due to larger sensors and optical zoom. Mid-wave was chosen for better resolution at the IR frequencies of it's intended targets and meteorological conditions.

[Speedy]

My late uncle used to be an RAF pilot. I was at sea, and he once told me, "There are two kinds of ships; submarines.... and targets."

I think I would prefer to be in the stealthy aircraft rather than the stealthy ship. I know some camouflage is astoundingly good, but a surface ship has to visually conceal itself and its wake.

[djcross]

btw what the different between DAS and EOTS , and why dont they use long wave IRST on F-35 ? , isn't the technology already available in AAS-42

The crispness of an image in the 3-5 micron wavelength makes automated target recognition easier to accomplish. 8-12 micron wavelengths provide longer range for the imager, but do not provide a crisp image unless it is close. If it is close, then there is no advantage over a 3-5 micron imager.

[SpudmanWP]

I found this comparison chart:

http://www.electrophysics.com/e/lwir...ir-imaging.asp

[ff1987]

See the difference in FoV between the different lens options. So the longer your range (at which you get a useful picture from the sensor) the smaller your FoV is. So at maximum range, searching with an IRST is like watching the world through a straw.

Not exactly, current IRST like EOTS, PIRATE, OLS-35 can scan a large volume of the sky like mechanically scan radar by repositioning itself.

See 6:45 video: http://www.youtube.com/watch?v=oKlQyPOiRuE

"IRST provides similar functionality to a radar without giving out electromagnetic radiation and can therefore provide full operational search and track functionality with a stealth capability."
http://www.defaiya.com/defaiyaonline...mid=50&lang=en

"The OLS-35 provides a coverage of +/-90 in azimuth and +60/-15 in elevation with a target acquisition range for non-afterburning aerial targets of 50 km facing up to target's front hemisphere and 90 km facing up to rear hemisphere."
http://www.deagel.com/Navigation-and...001926001.aspx

"A combined IRST/LR device for the Su-27, similar to the MiG-29's KOLS but more sophisticated, using a cooled, broader waveband, sensor. Tracking rate is over 25deg/sec. 50km range in pursuit engagement, 15km head-on. The laser rangefinder operates between 300-3000m for air targets, 300-5000m for ground targets.
Search limits are ±60deg azimuth, +60/-15° in elevation. Three different FOVs are used, 60° by 10°, 20° by 5°, and 3° by 3°. Detection range is up to 50km, whilst the laser ranger is effective from 300-3000m. Azimuth tracking is accurate to 5 secs, whilst range data is accurate to 3-10m. Targets are displayed on the same CRT display as the radar. Weighs 174kg."
http://aerospace.boopidoo.com/philez...20Avionics.htm

It was a discussion about IRST :
http://forum.keypublishing.co.uk/sho...t=38215&page=6

[seahawk]

Read the last tech specs. I bet that the longest range is achieved with the smallest FOV.

[ff1987]

Read the last tech specs. I bet that the longest range is achieved with the smallest FOV.

So prove me that you're right. Please give me a reliable sources. Sorry but I don't buy your opinion. Even if the FOV is small the sensor can scan a large volume of the sky quickly, just see above video about Gripen NG IRS&T. Also SAAB said that it work just like a radar ( see above link ).
But radar is still primary sensor as it isn't so vulnerable to atmospheric condition, and it has got much better range against non VLO target than IRS&T (today radar can detect 1 sq m fighter target 200km away, while IRS&T only 50km head on ).
But with sensor fusion IRS&T can give you some advantageous in EW environment, and still can detect VLO target much further than just radar.

[aditya]

Excellent thread and good points. One question, a lot of the discussion is on passive detection and ID technology using EO sensors. The ship will have a powerful radar - and current generation AShMs have long ranges ... doesnt the fighter have a upper hand thanks to Anti Radiation homing?

And haven't fighters had the upper hand since WW2 anyways? What does stealth technology on warships so drastically change to alter the equation?

[seahawk]

So prove me that you're right. Please give me a reliable sources. Sorry but I don't buy your opinion. Even if the FOV is small the sensor can scan a large volume of the sky quickly, just see above video about Gripen NG IRS&T. Also SAAB said that it work just like a radar ( see above link ).
But radar is still primary sensor as it isn't so vulnerable to atmospheric condition, and it has got much better range against non VLO target than IRS&T (today radar can detect 1 sq m fighter target 200km away, while IRS&T only 50km head on ).
But with sensor fusion IRS&T can give you some advantageous in EW environment, and still can detect VLO target much further than just radar.

Sure the Saab presentation is actually quite correct. The IRST sweeps the sky, as most IRST sensors are gimbal mounted and can be turned, so that they do not rely on their FOV alone to search the sky. The scan interval (time that passes between two "scans" of the same part of the sky) becomes longer, the smaller the FOV becomes. Add to the fact that the scan range are way more influenced by atmospheric conditions, the IRST is not providing the same situational awareness as a radar against non VLO targets. Against VLO targets it is more difficult to say, as this would depend on atmospheric conditions, the IR signature of the VLO target (reduction of iR signature is part of VLO design), the radar signature of the VLO target and the output power of your radar as well as the processing power of the radar.

Against planes the two sensor complement each other, giving the plane an improved SA. Against ground targets, the required processing power to auto detect and classify targets with an IRST increases in the same way as the needed processing power for the radar increases in such cases. I dare say that there are few planes flying that could auto detect a warship using the IRST alone, especially if there is lots of other ship traffic. So even in this case it is easier to combine both sensors, with the radar finding the contacts and the IRST identifying them.

[ff1987]

Sure the Saab presentation is actually quite correct. The IRST sweeps the sky, as most IRST sensors are gimbal mounted and can be turned, so that they do not rely on their FOV alone to search the sky. The scan interval (time that passes between two "scans" of the same part of the sky) becomes longer, the smaller the FOV becomes. Add to the fact that the scan range are way more influenced by atmospheric conditions, the IRST is not providing the same situational awareness as a radar against non VLO targets. Against VLO targets it is more difficult to say, as this would depend on atmospheric conditions, the IR signature of the VLO target (reduction of iR signature is part of VLO design), the radar signature of the VLO target and the output power of your radar as well as the processing power of the radar.

Against planes the two sensor complement each other, giving the plane an improved SA. Against ground targets, the required processing power to auto detect and classify targets with an IRST increases in the same way as the needed processing power for the radar increases in such cases. I dare say that there are few planes flying that could auto detect a warship using the IRST alone, especially if there is lots of other ship traffic. So even in this case it is easier to combine both sensors, with the radar finding the contacts and the IRST identifying them.

Agree

[moon_light]

Excellent thread and good points. One question, a lot of the discussion is on passive detection and ID technology using EO sensors. The ship will have a powerful radar - and current generation AShMs have long ranges ... doesnt the fighter have a upper hand thanks to Anti Radiation homing?

And haven't fighters had the upper hand since WW2 anyways? What does stealth technology on warships so drastically change to alter the equation?

not really because of LPI radar like AESA radar then anti radiation missiles and RWR will have a hard time , not to mention that to be able to measure range to launch missiles it require formation of at least 2 aircraft
in WW2 ship mostly use gun , missiles also not very agile , accurate so not very effective against aircraft by contrast ship can't out manuever a boom or missiles
but now the ship defense is much much better able to shot down missiles and boom very easy , not to mention jamming , and now with stealth ship the aircrafts may not even know where the ship is , before they are shot down

[moon_light]

Not exactly, current IRST like EOTS, PIRATE, OLS-35 can scan a large volume of the sky like mechanically scan radar by repositioning itself.

See 6:45 video: http://www.youtube.com/watch?v=oKlQyPOiRuE

"IRST provides similar functionality to a radar without giving out electromagnetic radiation and can therefore provide full operational search and track functionality with a stealth capability."
http://www.defaiya.com/defaiyaonline...mid=50&lang=en

"The OLS-35 provides a coverage of +/-90 in azimuth and +60/-15 in elevation with a target acquisition range for non-afterburning aerial targets of 50 km facing up to target's front hemisphere and 90 km facing up to rear hemisphere."
http://www.deagel.com/Navigation-and...001926001.aspx

"A combined IRST/LR device for the Su-27, similar to the MiG-29's KOLS but more sophisticated, using a cooled, broader waveband, sensor. Tracking rate is over 25deg/sec. 50km range in pursuit engagement, 15km head-on. The laser rangefinder operates between 300-3000m for air targets, 300-5000m for ground targets.
Search limits are ±60deg azimuth, +60/-15° in elevation. Three different FOVs are used, 60° by 10°, 20° by 5°, and 3° by 3°. Detection range is up to 50km, whilst the laser ranger is effective from 300-3000m. Azimuth tracking is accurate to 5 secs, whilst range data is accurate to 3-10m. Targets are displayed on the same CRT display as the radar. Weighs 174kg."
http://aerospace.boopidoo.com/philez...20Avionics.htm

It was a discussion about IRST :
http://forum.keypublishing.co.uk/sho...t=38215&page=6

At maximum range then the FOV of IRST may be only 3° so with mechanically scan it may take about 20 seconds for the IRST to scan a sector of 60°

[djcross]

There is an activation energy threshold for elements within the FPA. If the lens does not focus enough light onto the pixel/element, then an object goes undetected. The way to put more light on the element is to increase the magnification of the lens. As magnification increases, field of view decreases.

If you have ever used a telescope or binoculars, you have experienced this first hand. The telescope lens/retina acts in the same manner as IRST lens/FPA.

[ff1987]

At maximum range then the FOV of IRST may be only 3° so with mechanically scan it may take about 20 seconds for the IRST to scan a sector of 60°

Speculation. please sources.

[thinkplum]

so now the problem is whether DDG-1000s, LCSs or other stealth ships have comparable passive sensors that can pickup a stealth fighter and achieve a lock on at the same distance as the EOTS in a one-on-one scenario?

We know that whoever open the radar first gives away its position. Things will go awfully wrong especially for the F35 pilot, cause his radar is surely advanced but size does matters under these circumstances. But when it comes to opticals, stealth ships are in disadvantages since the discover distance will be effected by the curve of the earth, the humid air conditions, and etc. And if there is one piece of cloud between the 2, the F35 may also not able to pinpoint the ship from far away, if F35 flies at low altitude, the EOTS also can't fuction from afar.

So, i dont think there is a correct answer to this question.

If a stealthy ship is sent on a single special mission, F35 pilot need to be informed the approximate position of the ship to go search for it. and getting that information is already hard enough. If the Stealthy ships comes in packs and hold a defensive air recognition zone, F35s also has slight chances to go near enough to use EOST.



So, like the old man said, go with the subs.

[thinkplum]

The amibition (in terms of RCS) of most 'stealth' ships are far far far lower than what is deemed stealthy on an aircraft. Most of them only do the bare-minimum, reducing the specular return from the superstructure, but little else.

making you think a destroyer is a frigate is enough to tip over the balance.

[moon_light]

just finish watching this
part 1 http://www.youtube.com/watch?v=-bOktdtk62k
part 2 http://www.youtube.com/watch?v=6uvBVIsksR4
part 3 http://www.youtube.com/watch?v=jbYUelX9voA
quite useful info
it seem that some of you guy are right unlike stealth aircraft , stealth ship only try to look like fishing boat rather than be invisible , still have no idea how far a fighter can detected a fishing boat by radar 50 km ? , 100 km or 200 Km ?
BTW it seem that ship try to make slope to evade radar from other ship , but doesn't it look like the more slope they are , the more their surface reflect radar from the air ?
i mean look at this


the first ship have surface more perpendicular to radar from other ship than the second ship , but if an aircraft radar fly at altitude look at the ship doesnt the situation reverse ?

[SpudmanWP]

The TICO is not only perpendicular to the ocean (thereby presenting a very large return for inbound AShMs or other surface assets), it is full of 90 degree intersecting planes. This allows for a strong signal no matter what the angle the radar is coming from.

However, the LCS on the bottom not only lacks a strong return for surface assets, it has no 90 degree intersecting planes. It also aligns most of it's surfaces, even the mast. This ensures (just like the F-117, F-22, F-35, etc) that radar waves are all reflected in a uniform pattern. Just like other faceted designs, a radar that is exactly 90 degrees to the facet face will get a very brief & string return. The point is that this happens only once as the aspect of the radar to the ship is ever changing.

[Sanem]

a video on ARGUS, spotting a bird from 17,000 feet up, WTH?
http://www.youtube.com/watch?v=13BahrdkMU8

[moon_light]

a video on ARGUS, spotting a bird from 17,000 feet up, WTH?
http://www.youtube.com/watch?v=13BahrdkMU8

OMG , this **** is incredible , seem quite small as well may be fit on f-35 external pod

[SpudmanWP]

17k feet is only 3 miles. Update the EODAS sensor chips and add recording equipment and you would not need a pod in the F-35.

[moon_light]

17k feet is only 3 miles. Update the EODAS sensor chips and add recording equipment and you would not need a pod in the F-35.

the advantage of this sensor is that it have high resolution but also have very big field of view

[Tu22m]

17k feet is only 3 miles. Update the EODAS sensor chips and add recording equipment and you would not need a pod in the F-35.

Sounds like an affordable plan on one already cheap jet.

[Sanem]

my point was that if you can detect a bird at 3 km with optics, just imagine at what distance can you detect a war ship? even with a single camera, you can just scan area after area in a smooth movement, covering a huge area very fast

it also demonstrates very well the ability for automated tracking, anything from cars to even humans. I imagine a sea in motion will greatly complicate this process, but as I've said earlier ships with their straight lines should be easy for a computer to recognise, even at large distances, and thus track

I'm sure the F-35 can do this as well, but my beef is at what cost, $300 million for an aircraft with limited range and endurance? and the F-35 won't see IOC until 2018 at the very best (if ever), by then ARGUS will be a bolt on plug in option for any legacy aircraft at a cheap cost. and a few years later you just replace it with the next generation system, with the latest off the shelf sensors and processors, where the F-35 is supposed to last decades with 2010 technology. good luck with that, but by my count it'll be outdated by 2020

which is why I'm all for plug in technology, like the archetecture NG is using on its Firebird UAV, that way you can design a working platform that'll last for decades and just add the right sensors as the technology becomes available and the mission requires. kind of like putting the latest optics on a gun, no matter how old it is it'll greatly increase the potential if it just has a rail installed. better than a built in sighting system that allows for no other (AR-15, Steyr AUG) and quickly becomes outdated (especially in todays age where optics get better every year)

[swerve]

F-35 $300 million? Come off it! One doesn't have to fall for the $65 million nonsense to know that $300 mn is hugely overstated.

Agree with the bolt-on plug-in stuff, though.