Gripen - Red Flag

[Dr Freud]

Cost needs to be judged on complete package and through life support issues. Its not a simple equation. Having been involved with a few projects I can tell you that it's damn complex

Yes, and not least offset purchase and industrial share.


I'm having a question here btw: A radar, send out photons that bounce on something, and some of the photons will bounce right back to the radar, but what if that radar is covered with radar absorbing materials, is shaped to bounce away photons in an angle, : isnt this going to make this radar less effective ?

 

[kato]

isnt this going to make this radar less effective ?

You mean if the carrier of the radar is stealthed in those ways?

Well, for the radar-absorbing cover material, you could simply mount the radar system itself e.g. in a radar-transparent radome, or give it a "window"... and then absorb incoming radar that goes by the receiver by tunneling them through a trap mounted inside.

About the only aircraft fully shaped to reflect radar at non-compromising angles is the F-117 - and that has no radar itself, only FLIR.

 

[Ozzy Blizzard]

Yes, and not least offset purchase and industrial share.


I'm having a question here btw: A radar, send out photons that bounce on something, and some of the photons will bounce right back to the radar, but what if that radar is covered with radar absorbing materials, is shaped to bounce away photons in an angle, : isnt this going to make this radar less effective ?

As far as shapeing goes it would only have an effect on incoming emmitions, due to the way its shaped.

AFAIK the RADOME on the front of the platform doesnt give much of a return anyway becasue its partially transparant to radiowaves in the right wavelengths, i.e. it needs to be so the radar can work. So it may even be the case that the radome itself has very little or no RAM, which is probably why they are painted a different colour on the F-22A & F-35A. The problem with frontal aspect RCS reduction is the return from the radar & antenna assemly itself. AFAIU in addition to the engine face the radar antenna is the single largest contributor to frontal RCS, and manageing this was one of the major ways the F/A-18E/F reduced its fronal RCS.

Anyway you have to remember the huge difference in power at the radome between outgoing and incomeing emmitions. The platforms radar would probably be putting out energy in the kilowatt range (1~7kw, Ibris is stated to have a peak power output of 21kw[!]) compared to the incomeing which should be in the hundred to tens of watts range. RAM would have a relatively negligable effect on the outgoing considering the concentration of the beam, but a much greater effect on the diffused, and much less powerfull incomeing beam.

Note the radome's color difference:

 

[Dr Freud]

I just read this :

Stealth works in various ways, and stealth aircraft use a combination of techniques. The basic concept, however, is to make the stealth RAM coating one-fourth of a radar wavelength thick. In this way, some of the enemy radar beam is reflected by the surface of the RAM and more by the metal under the RAM later. Because this second element travels a half of a wavelength farther than the first element, it exactly cancels out the radar wave.

and got another question: is B2, f117, f22, f35 the only planes being painted with RAM ?

 

[Ozzy Blizzard]

I just read this :

and got another question: is B2, f117, f22, f35 the only planes being painted with RAM ?

AFAIK the F/A-18E/F has RAM coatings on some critical area's like intake edges.

 

[Dr Freud]

That makes sense, i think they reduced the RCS to 1/5 compared to C/D.
If RAM maintenance is that costly, why not just spray it on on the planes that are going to have use of it during exersizes, and leave the others as they are until there is an actual need for it ?

Can you tell me what stumble it/tag this thread/clesto/digg/reddit/furl/del.icio.us/spurl means ? how and why should i use it ?

 

[gf0012-aust]

I just read this :

and got another question: is B2, f117, f22, f35 the only planes being painted with RAM ?

RAM is not a "painted on" solution per se.

Its platform specific - area specific and geared as such to deal with the likely threat.

It can account for far less than 20% of a platforms signature management. In some cases it's also a thickness issue.

You also cannot just "paint it on" . on early platforms it was literally applied as a blanket (and it was actually called a RAM Blanket).

 

[Salty Dog]

Thanks slydog.

"As speed decreases, therefore, angle of attack must increase to maintain the same lift and the same cruising altitude."
This means the aircraft can fly slower, wich is good if you want to land on a short airstrip. It also helps you loiter more efficiently.
It has nothing to do with fighting ability, as has been touted like a mantra.

While in general terms you are correct about increasing AoA to compensate for reduction in airspeed, you can also change the shape of the wing via flaps/slats to increase lift which normally takes place during take off and landing.

For loitering you would not be using flaps/slats.

 

[Salty Dog]

As far as shapeing goes it would only have an effect on incoming emmitions, due to the way its shaped.

AFAIK the RADOME on the front of the platform doesnt give much of a return anyway becasue its partially transparant to radiowaves in the right wavelengths, i.e. it needs to be so the radar can work. So it may even be the case that the radome itself has very little or no RAM, which is probably why they are painted a different colour on the F-22A & F-35A. The problem with frontal aspect RCS reduction is the return from the radar & antenna assemly itself. AFAIU in addition to the engine face the radar antenna is the single largest contributor to frontal RCS, and manageing this was one of the major ways the F/A-18E/F reduced its fronal RCS.

Anyway you have to remember the huge difference in power at the radome between outgoing and incomeing emmitions. The platforms radar would probably be putting out energy in the kilowatt range (1~7kw, Ibris is stated to have a peak power output of 21kw[!]) compared to the incomeing which should be in the hundred to tens of watts range. RAM would have a relatively negligable effect on the outgoing considering the concentration of the beam, but a much greater effect on the diffused, and much less powerfull incomeing beam.

Note the radome's color difference:

Wait a second mate! By your comment, you would be able to radiate your radar, but you would be unable to receive.

The radome can not be RAM coated or it would block any incoming RF energy, especially any reflected RF from your own radar. So you would still need a radar (RF) transparent radome.

If you've looked closely at radar or communications domes (which are RF transparent) they are labeled "do not paint" which is why they are a different color.

 

[Ozzy Blizzard]

Wait a second mate! By your comment, you would be able to radiate your radar, but you would be unable to receive.

Which is why i said most probably dont have any.....

The radome can not be RAM coated or it would block any incoming RF energy, especially any reflected RF from your own radar. So you would still need a radar (RF) transparent radome.

If you've looked closely at radar or communications domes (which are RF transparent) they are labeled "do not paint" which is why they are a different color.

This is exsactly what i said.

 

[Dr Freud]

I just realized something: if the RAM coating is exactly 1/4 of a wavelength thick, in order to cancel out the radar wave.
Well, if that radar wave is shorter or longer, it wont cancel out! perhaps this is the reason why all the talk about older soviet radars can pick em up, they have longer radar wave then what is present on todays fighters, and what the RAM coating is designed to cancel out.

A fighter radar today, can it use different wavelengths ?

If shaping is the primary mean to not bounce right back, this would be partly neglected by using radar recievers spread out to catch the deflected photons, and using datalink to gather info from them all, via triangulation.
Of course, if the stealth fighter goes active, it is no more stealthy then an AWAC.
I wonder how much space it would require to fit in an homing on radar in an A2A(ir) missile, and what it would cost extra.

 

[gf0012-aust]

I just realized something: if the RAM coating is exactly 1/4 of a wavelength thick, in order to cancel out the radar wave.
Well, if that radar wave is shorter or longer, it wont cancel out! perhaps this is the reason why all the talk about older soviet radars can pick em up, they have longer radar wave then what is present on todays fighters.

A fighter radar today, can it use different wavelength ?

I was going to stay out of this, but the debate is becoming ridiculous. I tried to allude to this earlier.

RAM coatings aren't wavelength tuned by application thickness.

 

[barra]

I was going to stay out of this, but the debate is becoming ridiculous. I tried to allude to this earlier.

RAM coatings aren't wavelength tuned by application thickness.

Yes you should stay out of it gf, some of these theorys being put forward are quite entertaining.

 

[gf0012-aust]

Yes you should stay out of it gf, some of these theorys being put forward are quite entertaining.

I'm torn between issues of responsibility, frustration and whether people are really just mucking around in here and that none of this is actually informed and serious debate.....

 

[Dr Freud]

No, not mucking around, i admit i dont know "stealth", i'm trying to get info about it here with the topic tho. and i just recieved the info that: RAM coatings aren't wavelength tuned by application thickness.
If its not classified, i would like you to explain what it is.

 

[Salty Dog]

No, not mucking around, i admit i dont know "stealth", i'm trying to get info about it here with the topic tho. and i just recieved the info that: RAM coatings aren't wavelength tuned by application thickness.
If its not classified, i would like you to explain what it is.

Try these mate:

Airborne Stealth in a Nutshell - Part I
http://www.harpoonhq.com/waypoint/articles/Article_021.pdf

Airborne Stealth in a Nutshell - Part II
http://www.harpoonhq.com/waypoint/articles/Article_022.pdf

 

[gf0012-aust]

No, not mucking around, i admit i dont know "stealth", i'm trying to get info about it here with the topic tho. and i just recieved the info that: RAM coatings aren't wavelength tuned by application thickness.
If its not classified, i would like you to explain what it is.

I'm not going to expand upon my previous. What I was trying to do was to stop the discussion from entering nonsensical theories. I won't go into more detail.

However, open source material, try: Airborne Radar Book by George W Stimson. $100 for AOC Members, unsure what it is for public access

 

[Dr Freud]

Thanks salty:cheers thats more info then i was even hoping for.
Now i also know that guy was referring to RAS when he mentioned self-canceling.
On top of it all, i also got some insight in jamming

 

[gf0012-aust]

Now i also know that guy was referring to RAS when he mentioned self-canceling.

There's no such thing as self cancelling.

It's a degree of active management - and that will be a wavelength opportunity at a point in time.

No disrespect intended, but if it's someone touting the alleged capabilities of plasma stealth and/or spectra - then on a fighter sized aircraft, thats just plain unmitigated voodoo science rubbish IMO.

The onboard power and assoc technology aren't convergent at this point in time. esp with current onboard power systems.

my 2c anyway. :rel

 

[Dr Freud]

It's a degree of active management - and that will be a wavelength opportunity at a point in time.

If you with this mean a moment of luck, yes, i agree.
I also agree plasma at this time seem premature, and it will also increase IR signature, i dont really believe in the whole active thing.

Another thing, someone (cant remember who or where) said an infrared seeker can only search a narrow field.
While that was true on older IR, its not a problem on IIR. page 9 article 22