Methods of making an aircraft stealth

[Oqaab]

As far as I know there are two methods of making an aircraft stealth. And they are as follows,

1. When the radar rays strike the aircraft, they return back to the radar and give the information about the aircraft. To avoid the rays going back to radar, the surface of an aircraft is made irregular so that the rays get scattered and cant go back. The F-117 nighthawk uses this method.

2. Carbon (mostly) or ferrite composite materials are used over the surface of aircraft to absorb radar rays. The radar absorbing paint also helps (to some extent) in absorbing rays. This give a low RCS. Current fighters like Eurofighter and F/A-22 Raptor uses this method.

If anybody knows some more, then plzzz share. And correct me if I m wrong.

Need sencible replies.
Thanx. :)

[suleman]

Its all the game of electro magnetic signals.All signaling and radrs are working with electromagnetic signals and waves.
Now basically radars are of two types
1)Active radars (they work in ommiting radioactive rays and then catch the reflected waves and then find cordinates and exact positioning of aircraft)

2)Pasive radars (they basically dont ommit radioactive signals but are very sensitive and capable to catching any radiactive signals from very low to very high frequencies).

Now its upto u to make such technology or metal which is invisible for these electromagnetic waves.
For this first is that we find such material which absorbs these electromagnetic waves.Actually they do not absorb electromagnetic waves what they do is that they dont reflect back these rays.As magnet gets attached to metal but if u bring it close to plastic then it wont work.Similar is the case with electromagnetic waves.They can not pass through metals,and reflected back and from their angle of reflection we can find the position of aircraft w.r.t X and Y axis.

Now we can make such metal or material or paint which does not reflect such rays,but radar makers are also clevaer and find alternatives.Certainly a fighter is in contact with its base or settelite etc and its self use signals for its own radars and communication so we can trace those signals and find the position of source which is ommiting such radiation.This cud we find on the principle that more u go nearer to the source more strong signals to recieve.The point where this signal frequency is MAX is position of that aircraft or missile.Passive radars plays an important role in this.
I hope this will clear some of ur points i tried to tell it in as simple words as i can to help oters understand.
Thanks.

[gf0012-aust]

Stealth design issues:

This depends on tasking requirements, but if we assume that the aircraft is going to go in harms way and is designed to shoot and scoot priority targets as opposed to targets of opportunity, then we can consider the following:

Electronic emission issues:
Eliminate active radar and use Low Probability Intercept (LPI) in onboard signal and sensor use. YThis generally entails the use of spread-spectrum, burst-mode or highly modulated signals with a substantially reduced peak power level. Transmission times involve detection characteristics that resemble electronic background noise in transit to the target. Any radar system would employ reduced sidelobe emissions to reduce the chances of detection during active stages.

Thermal signature issues:

Elements such as the leading edges of the wings, which become heated by air friction in flight, can be internally cooled by pumping fuel or hydraulic fluid around and through them.

Engines intakes and exhausts to be mounted above the wings, out of "sight" of heat-seeking SAM's, MANPADS, etc.

Optical illusion:
Blend lights into the lower surfaces of the aircraft in an attempt to blend the visual silhouette into the sky background.
This has been done in the past through projects such as the Compass Ghost programme.
Counter shading

Overall aircraft colour:
Scattered light from dust and clouds reflects onto an aircraft's underside. Even black aircraft below 50,000 ft will be visible due to this phenomenon. Most aircraft for that reason are painted a low visibility grey to take advantage of low light levels. Black aircraft are useful at night (hence why their missions are usually nocturnal). Another example is the pink coloured landrovers used by the British SAS. Pink is the best colour for desert conditions and is harder to identify than the typical beige or cammo coloured vehicles.

Aerodynamic effects, contrail suppression:

Some aircraft have contrail detectors built in which monitor contrail side effects, these can be countered by chemicals injected into the exhaust plumes using chlorosulphonic acids, various alcohol mixtures, etc) for suppression

Radar cross section:

depends on three main factors:

- geometric cross section

- directivity

- reflectivity

all three need to be dealt with and are complicated within themselves

Absorbent structure and design:

eg, laminated rubber
GRP composite layer
honeycombing
lossy impregnation of foam
conformal shaping
plastic laminates
frequency-selective surfaces
reflector films

Combining these structures with thermal infrared and visual camouflage properties results in an increased low observability.

The airframe, shape of the plane has a considerable impact on the design, but the issue of noise and vibration also has to be attended to to end up with a complete solution

Stealth design has to be a complete solution, dealing with just the RCS will work against ground based sweepers, missile systems, and interceptor radars, but the RCS is frontal only.

That means that Stealth can be tracked by a sophisticated AWAC's (especially if it knows the relative flight corridor). Systems such as Australias JORN OTH radar system can spot stealth platforms.

I actually believe that stealth aircraft are at the other end of the life cycle now. The US was using stealth aircraft for approx 8 years before they were released into the public. That would indicate to me that although stealth is an obvious force multiplier in the majority of theatre, the US has come up with other solutions in its place.

One of the things that the US has done consistently well is to build leading edge aircraft, and be a generation ahead of the nearest competitor (eg A12, SR71, U2, TRS2, F117, B2 etc...)

If they have started to develop technologies elsewhere and not around a stealth focussed solution, then that would indicate to me that they already know how to counter stealth and are devloping new platforms.

Stealth in UCAVs/TUAVs in a network centric environment, stealthy ordinance, and C41 managed from space is going to render a lot of air forces uncompetitive.

I think stealth emphasised manned aircraft probably have another 10 years left.

Stealth on other platforms is just as complex and involves other issues to be considered at the design stage.

[suleman]

One of these systems is the "electrochromic polymer" that is being developed at the University of Florida. These thin sheets cover the aircraft’s skin and sense the hue, color and brightness of the surrounding sky and ground. The image received is then projected onto the aircraft’s opposite side. When charged to a certain voltage, these panels undergo color change. Another similar "skin" is being tested at the top-secret Groom Lake facility at Area 51 in Nevada. It is reputed to be composed of an "electro-magnetically conductive polyaniline-based radar-absorbent composite material." The system also utilizes photo-sensitive receptors all over the plane that scan the surrounding area, subsequently the data is interpreted by an onboard computer which outputs it much like a computer screen making the aircraft virtually invisible to site.

[gf0012-aust]

One of these systems is the "electrochromic polymer" that is being developed at the University of Florida. These thin sheets cover the aircraft’s skin and sense the hue, color and brightness of the surrounding sky and ground. The image received is then projected onto the aircraft’s opposite side. When charged to a certain voltage, these panels undergo color change. Another similar "skin" is being tested at the top-secret Groom Lake facility at Area 51 in Nevada. It is reputed to be composed of an "electro-magnetically conductive polyaniline-based radar-absorbent composite material." The system also utilizes photo-sensitive receptors all over the plane that scan the surrounding area, subsequently the data is interpreted by an onboard computer which outputs it much like a computer screen making the aircraft virtually invisible to site.

The problem with this technology (as it currently stands) is that it cannot cover sufficint areas to be of tactical benefit. It also is also only going to useful in a benign environment. The power to drive it, the restrictions in where it can be used make it of limited value at present.

certainly in a war theatre where there is no EW capability it can be used, but against an OTH system it will stand out even though it may not be "visible" to someone standing 200m away. The power to drive these technologies creates an ECM signature in itself, and that tends to neutralise practical use. as each system to some extent can impact on another. thats why stealth is also a series of compromises.

Technically you could turn the hull of a ship into one big peltier surface thus rendering it signature free in an IR environment. BUT, it would be radiating enough power to power up a small city. ;)

[elkaboingo]

well this isnt exactly radar stealth but there is a way to prevent infrared signature that does not use electricity or anything. its more like a camoflauge net. you usually put it over sams or arty guns. pakistan makes it so im sure most western countries have it. anyone know what im talking about.

[gf0012-aust]

well this isnt exactly radar strenght but there is a way to prevent infrared signature that does not use electricity or anything. its more like a camoflauge net. you usually put it over sams or arty guns. pakistan makes it so im sure most western countries have it. anyone know what im talking about.

its a bit hard to fly a fighter with a camo net on it - or for that manner drive a frigate around the ocean... ;)

[elkaboingo]

no its for ground installations like SAMs and arty guns

[gf0012-aust]

no its for ground installations like SAMs and arty guns

I know, that's why I had the smiley at the end of my post.... :D

[elkaboingo]

i see :P

[suleman]

One of these systems is the "electrochromic polymer" that is being developed at the University of Florida. These thin sheets cover the aircraft’s skin and sense the hue, color and brightness of the surrounding sky and ground. The image received is then projected onto the aircraft’s opposite side. When charged to a certain voltage, these panels undergo color change. Another similar "skin" is being tested at the top-secret Groom Lake facility at Area 51 in Nevada. It is reputed to be composed of an "electro-magnetically conductive polyaniline-based radar-absorbent composite material." The system also utilizes photo-sensitive receptors all over the plane that scan the surrounding area, subsequently the data is interpreted by an onboard computer which outputs it much like a computer screen making the aircraft virtually invisible to site.

The problem with this technology (as it currently stands) is that it cannot cover sufficint areas to be of tactical benefit. It also is also only going to useful in a benign environment. The power to drive it, the restrictions in where it can be used make it of limited value at present.

certainly in a war theatre where there is no EW capability it can be used, but against an OTH system it will stand out even though it may not be "visible" to someone standing 200m away. The power to drive these technologies creates an ECM signature in itself, and that tends to neutralise practical use. as each system to some extent can impact on another. thats why stealth is also a series of compromises.

Technically you could turn the hull of a ship into one big peltier surface thus rendering it signature free in an IR environment. BUT, it would be radiating enough power to power up a small city. ;)

Dear no human system has ultimate perfection.What we doing is dodging a sysytem and then they will catch u from someother way.Secondly one have to sacrifice few things to achieve something.Soo all these stealth technologies also have flaws.They make tech to beat radars and radar tech improves to catch them again. :)

[gf0012-aust]

yes, it is a process of continual improvement, the other thing that you should be cautious of is that some things are released on the internet deliberately - it doesn't mean that the project has any susbstance. The surface reactive skin layer (as described above) is a favourite for Area 51 advocates as it fits into some pet theories about "shape shifting" aircraft etc.....

the USNONR has spent lots of money looking at things like squid and chameleon to try and identify why and how they can change colour. There are already paint schemes that at certain wavelengths and altitudes render the aircraft "invisible" to a human eye (at a proscribed distance)

[Awang se]

About the spread spectrum, we build an experimental machine. tell u what, once they try to ranging a test object with it, it detect a target and several ghost targets. there is many dots and only one is real. Do you know why this happen?

[gf0012-aust]

you're using a doppler or phased array radar system?

[Awang se]

I think it's doppler,

[Awang se]

Phased array and doppler? i don't understand the question. The system using phased array antena with doppler shift detection for low flying target.

[Awang se]

Oh my god! i figure it out already, i guess the problems lies in the doppler shift differential section.

[gf0012-aust]

and you are getting ghosted returns on any sized aircraft or just one particular type?

[gf0012-aust]

Oh my god! i figure it out already, i guess the problems lies in the doppler shift differential section.

only if you are getting universal ghosting

[Awang se]

Let's go on with the topics. U notice, when we two talk, others slunk away to the sidelines.

[gf0012-aust]

sorry fellas for hijacking the thread!

[Awang se]

That make us thread terrorist.

[gf0012-aust]

Back to detecting stealth aircraft....

Australia's Jindalee system spotted F117s flying over Baghdad during Desert Storm. At that stage, the Jindalee portion was the only part of the JORN OTH system in operation. The publicly disclosed range of JORN is about nine million square kilometres. The system is now fully operational.

Our agreement with the Americans under which we give them all our intelligence from JORN is called Project Dundee. ;)

[Aussie Digger]

Gf, I've read comments about the future of Australia's FA -18A/B fleet that future phases of the HUG program will include modifications to reduce the radar signature of the Hornets. What do you think this will involve? Structural modifications along with avionics changes (to LPI equipment) and perhaps a radar absorbent type "paint job"? Or are these comments just hubris to impress uninformed types like myself?

[gf0012-aust]

Gf, I've read comments about the future of Australia's FA -18A/B fleet that future phases of the HUG program will include modifications to reduce the radar signature of the Hornets. What do you think this will involve? Structural modifications along with avionics changes (to LPI equipment) and perhaps a radar absorbent type "paint job"? Or are these comments just hubris to impress uninformed types like myself?

There are certainly ways to bring the RCS down, but I would question whether its worth the effort. As soon as the aircraft flies "dirty" ie, with external weapons mounted, you have just advertised your presence.

The F117 is consistently stated to have the RCS of a steel ball bearing, the B2 is supposed to have the RCS of a golf ball, the B1 an RCS of a tennis ball. All of those aircraft have clean bodies and internal weapons bays.

The Hornet, SU27, Mig 29, SU32 etc are not designs that can be reconfigured to be "stealthy". You can do it, BUT, once the racks are full, your ID is up for every radar system to see.

[Aussie Digger]

Yeah I've heard that but maybe it will allow our rather short legged Hornets to get close enough to fire our new (promised, not yet delivered) standoff missile before they're shot down?

[gf0012-aust]

a couple of my more informed colleagues have not expressed any concern about this. They are of the firm belief that the future force mix will be the most long range capable in the region. I can only assume that other goodies are in the shopping trolley yet to go through "checkout".

They've done sims on all the existing and projected russian and french aircraft with the future capability profile (and I'm assuming that there are some undeclared items in the list) and haven't blinked.

"dunno" again

[Aussie Digger]

Well, if we are going to remain "long range capable" than some things will have to happen. 1. Fitting Hornets with conformal tanks. I don't know if this is possible but it would certainly help and go a long way to resolving the problems with the lack of hard points on the FA-18 for weapons. 2. Additional air to air refuellers, although this creates additional problems with the requirement for escorts etc, not to mention cost... 3. Additional use of AP -3C and/or transport aircraft as "missile shooters" again this has the problem of requiring escorts, and survivability issues from the large slow unprotected aircraft being used in a role it wasn't designed for. Except for the conformal fuel tanks, I don't see that either of the other options will provide greater capability than what we have now. I think the only way to improve this and rid ourselves of the F-111 would be to acquire the F15E or maybe the Super Hornet. The Government and the RAAF seem deadset against that though.

[gf0012-aust]

True on the interim, but the US wants to redefine the JSF deliverables again, which will blow out our acceptance by another year. If the pigs are pulled within 2-6 years, then I think we will end up with F15E's.

My personal preference is for an F15 rather than an '18e/F.
Better plane, longer legs, better missile truck, better bomb truck, and a better anti-shipping platform.

The AP-3C's will end up with stand-offs in the end. and yep, we do need more AAR. Minimum of 7, preference for 9. 3@ fleet west, 3@ fleet east and as a backup for micronesia and NZ, 3@ the top end.

[Aussie Digger]

Yes, a purchase or lease of 50 or so F 15E's would mean that we could retire our pigs and a goodly number of our oldest (n airframe terms) FA-18's and still keep our air defence and strike levels at the standard it's at now both in numbers and quality and perhaps even improve our capability. We might even save some money doing it as well, with money saved from upgrades and maintenance of the F111's and FA-18's. It would at least provide us with unsurpassed capability within our own region and provide a valuable capability for Coalition operations.

[gf0012-aust]

Its more likely that we will end up with some of Canadas airframes, unless they do a very rapid 180, they will end up like NZ.

[Aussie Digger]

Yeah I've read that they've already retired 19 non upgraded Hornets which would benefit our fleet in the event of an early withdrawal of our F-111's. They would have to be upgraded unless you want to experience the F-111G problems all over again...

[Aussie Digger]

Not that it really matters, it'll happen or it won't but I'm not convinced that equipping AP -3C's with standoff weapons is the right way to go. If they are used in a high intensity conflict, the missile better have an unbelievable range or the firing platform will be in trouble. A PC-9 armed with a 0.50 calibre gunpod could shoot one down. If it's to be used in low intensity warfare, why are mega-expensive standoff weapons being used in such a scenario anyway?

[gf0012-aust]

Not that it really matters, it'll happen or it won't but I'm not convinced that equipping AP -3C's with standoff weapons is the right way to go. If they are used in a high intensity conflict, the missile better have an unbelievable range or the firing platform will be in trouble. A PC-9 armed with a 0.50 calibre gunpod could shoot one down. If it's to be used in low intensity warfare, why are mega-expensive standoff weapons being used in such a scenario anyway?

Well, they are long range, capable of loitering, ideal for LR anti-shipping and if push comes to shove can throw things at ground targets. Didn't the Kiwis have mavericks on theirs? Plus they can look after themselves. If they went into somewhere hot they can be railed with Sidewinders. Plus I imagine in a hot theatre they would be part of a box of tricks including AWACs, AAR and CAP.

/back to thread topic.

they aren't very stealthy though... ;)

[elkaboingo]

Back to detecting stealth aircraft....

Australia's Jindalee system spotted F117s flying over Baghdad during Desert Storm. At that stage, the Jindalee portion was the only part of the JORN OTH system in operation. The publicly disclosed range of JORN is about nine million square kilometres. The system is now fully operational.

Our agreement with the Americans under which we give them all our intelligence from JORN is called Project Dundee. ;)

jeez, thats all i've been hearing, russians deteced f-117, old british destroyer detected f-117, austrailians detected f-117, so and so detected f-117, commercial airliner weather radar detects f-117 200km out, whats wrong with this plane? or are radars just getting that good? will f-22 not be stealth when it comes out? :?

[gf0012-aust]

Back to detecting stealth aircraft....

Australia's Jindalee system spotted F117s flying over Baghdad during Desert Storm. At that stage, the Jindalee portion was the only part of the JORN OTH system in operation. The publicly disclosed range of JORN is about nine million square kilometres. The system is now fully operational.

Our agreement with the Americans under which we give them all our intelligence from JORN is called Project Dundee. ;)

jeez, thats all i've been hearing, russians deteced f-117, old british destroyer detected f-117, austrailians detected f-117, so and so detected f-117, commercial airliner weather radar detects f-117 200km out, whats wrong with this plane? or are radars just getting that good? will f-22 not be stealth when it comes out? :?

To be fair the F117 is 15-17 years old, so detection opportunities should have improved, and they improved only because there was a requirement to find them.

I take a different view than some of my associates, I think that stealth manned aircraft have a limited future. The F117 has an RCS the size of a steel ballbearing, so that means that it will still be usefull in the majority of the worlds nations. Otherwise, all it means is that the tasking for it is different than what it was say 4-5 years ago. Now it has an F15e that might provide partial CAP.

I firmly believe that once the US declares a technology, it is because it already has moved on to something more efficient or useful.

after all, they flew the F117 on missions for 9 years before it was announced.

as for the F22, its role is different from the f117, it will all get down to an issue of tasking that determines whether it is compromised in a theatre.

its not the F22 I'd worry about, its the aircraft that has replaced the f117 that I would be concerned about.