highsea

Dima, I grow weary of explaining the simplest concepts to you. Just when I think the lights might be coming on inside your head, you prove me wrong again.

Let me point something out for you. Why do you think radars are rated based on target size? In other words, the same radar may have a reception range of 50km for a 1m^2 target, and 100km for a 10m^2 target. Do you understand that this range is directly related to the RCS of the target? Do you understand that 10m^2 is LARGER than 1m^2?

This means, that no matter what the target, the RCS, and thus the detectable range, is related directly to it's size. I don't care if you are talking about a stealth aircraft or a 747. You can take a B2 Bomber, which has a very low RCS for it's size. But if you were to build it twice the size, using the same materials, etc, the result would be a plane with a proportionately larger RCS. The same applies if you were to shrink it to the size of an X-47. It would be more difficult to detect, because it's a smaller target.

A RADAR'S ABILITY TO DETECT A TARGET IS DEPENDENT ON THE STRENGTH OF THE RETURN.

This is why I asked you which has a larger RCS, a 747 or a C152. You apparently didn't get the point. But I am not surprised, because you rarely do if you don't want to.

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Dima

wow, you're dumber than i thought, do you actually think that i made this idea, i'm just taking someone else's information and absorbing it, once i think that you've turned into a civil and forgiving person, you prove me wrong, every time, you're so full of it and think you're so high, pathetic, hate people like you

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highsea

Lol, take a pill, Dima.

This was your statement: "an aircraft's size does not affect it's RCS". Now, I don't care if it was your idea or someone else's, it's not true, no matter where it comes from. If you have a problem with that, there's nothing I can do about it.

Dima

oh yes, i forgot about that, ("10m^2 target" etc.) well, then what could they have meant, i mean, these are respectable people, who have great knowledge in their field, could i have misinterpreted something? did you even read the article? you really need to cool down buddy, not everyone is so geeky enough that they spend all their time researching planes etc. i try to have a life too

highsea

Dima, I'm cool, and I have a life- you don't need to worry about me. I didn't read the article, so I don't know if you misinterpreted it or if it was just inaccurate. I suspect you misinterpreted it if the source is reputable. Let me explain a couple things.

Size is not the only factor, nor is it necessarily the most important one in a target's RCS. But to say it is not a factor is just plain wrong. Leaving stealth technologies out of the picture for a moment, imagine a real SU-30 vs. a radio controlled model, perfect in every detail and made of the same materials. Obviously the larger one is going to give a stronger return. I'm sure you can understand that, so you can understand that size is a factor.

So, what other factors are there? The two other main factors are shape and materials. Let's look at materials first- some materials such as metals (aluminum, steel, titanium) give stronger returns than other materials like fiberglass or other composites like carbon fiber. In other words, they are more reflective. So take two objects the same size, one made out of aluminum will give a stronger return than one made of fiberglass. The radar signal will penetrate the fiberglass, and bounce off the aluminum. If there is metal behind the fiberglass, the signal will reflect off that metal, and you will still get a return, but it will be weaker because some of the energy is absorbed by the fiberglass. This is why putting radar absorbent paint or composite skin on an AC can only give you so much- you need a sympathetic airframe also.

Next you have shape- signals will reflect in a predictable way. A 90 degree angle will reflect straight back to the transmitter. A 45 degree angle will reflect 90 degrees to the signal, or straight up, down, or to the side, depending on orientation. You can use shape to prevent the receiver from getting a return. No return, no target.

With the exception of active signal cancellation, all stealth designs take these three main factors into consideration.

About radars:

A transmitter's power output has an effect on the range, but that is only the output side of the picture. You don't get a target until you get a return. Remember that! So a 50KW transmitter will see a 10m^2 target farther away than a transmitter with only 5KW of output power. They are both looking at the same target, and one has more transmitting power, so it has a greater detection range (assuming equal sensitivity on the receivers). But if you reduce the RCS of the target that the 50KW radar is looking at to 1m^2, they will both detect at about the same range. The smaller RCS of the target negates the higher power of the larger radar. This is an oversimplification- it's not a direct linear ratio, the inverse square rule applies. And remember all radar is line of sight! You can't see over the horizon with standard radars. The range is always limited by the radar horizon. Elevate the target or the antenna, and you increase the range. Put them both on the ground, and you have a max range of about 8 miles, because the curvature of the earth makes the target invisible. Pilots use this to "fly under the radar".

Doppler shifts:

Radar waves obey certain laws. That's why you can use doppler shifts to measure the speed of an object. The wavelength is compressed for an object moving toward the receiver, and is is stretched for an object moving away. By measuring this stretching or compression of the wavelength, you can determine the speed and relative motion of the target. Targeting radars usually filter out objects that do not have doppler shifts- they do this to eliminate background returns, so they can distinguish a moving target against a static background. This is why a pilot can "notch" a radar- if he can stop all forward motion relative to the receiver, the filters will reject the signal as background noise. Pilots use this technique to confuse a missile or a targeting radar. When you beam a command guided SAM, you beam the radar, not the missile.

There are other considerations, depending on what you are trying to do. Certain frequencies work better for certain things than others. Atmospheric conditions always have an influence. But the basic rules always apply.

Edit to add: Dima, After writing this, I decided to read your article. It confirmed exactly what I said wrt size and shape. They did not discuss materials in depth, but if you note the formula for RCS, material is factored in. The parenthesis is mine, so you see the correlation. RCS=Projected cross section (size) x Reflectivity (material) x Directivity (shape)

Anon

LOL, poor Dima.

Maximus

Nice informative article there Highsea.

I feel enlightened.

AchtungSpitFire

This thread is pretty redundant to begin with. The LCA is another Indian DRDO/HAL pipe dream (arjun,ADS,MiG-21'upgrades') and the F-16 is proven evolved multi role fighter.

I genuinely feel sorry for all the Russian apoligists within the Indian security establishment who out of sheer disregard for facts or by being naive believe that under any circumstance that Russian hardware post 1970 have any kind of parity with their western counterparts. Time and again this has been proven true in the skies and on the battle field.

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ajaybhutani

Then this thread is a good cheance for u to prove this point of urs with facts .

Cybertraker

Ajay do you think these MiGs will survive till 2015 at the rate they are crashing day by day. At current rate they will be finished in next few years. Otherwise they wouldn't have been named as "Flying Coffins". Killing more Indian pilots.

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Live life King size :cool:

Dima

i know that it's not the only factor, i may be "dumb" by your accounts, but not that dumb, how long have you been studying this sutff for? i've only been studying for about 1.5 years, so i got a lot of time to learn this kind of stuff

yes,RAS is important, RAM, and radar-dissipating paint, any other ways to reduce the RCS?

please, don't treat me like i'm an utter baffoon, come on, i know most of this stuff

stealth i understand, just radars and how they work i need to learn some more on

what does 10m^2 mean?is 10m the target size, and ^2 the amount of targets it can track at that size?

oh yes, my teacher taught me a bit about doppler radars

so, when you notch a radar, how fast, i mean what's the max speed that you can go at to notch it?

yes, thank you, sorry for my, "emotional" blow-up, lol, poor Dima
what can you do, only 15, damn puberty and these mood swings

highsea

A few years, Dima. I retired from aerospace when you were about five.
Yes, but the important considerations are the ones I mentioned. If you don't do those first, whatever else you do won't help much. There are ways to target specific areas of an AC with additional techniques, such as selective screens on emitters and active cancellation, but ultimately you must make the target as small as you can, scatter what you can, and absorb the rest. If you were to look under the skin of a B2 or F-22, you would be amazed. The signals penetrate the skin, and what doesn't pass through or get absorbed gets trapped by the airframe- it "eats" the radar waves.
It means ten square meters- it's a measure of area. The ^ symbol means the 2 is the exponent. 10m^3 would mean ten cubic meters.
The speed you are going is irrelevent- what matters is that the speed relative to the emitter is zero.
Lol, don't worry kid, we've all been there.

ajaybhutani

not really. the ones that face the most of the crashes are older mig versions. only 120 of the mig21 will be kept till 2015 which have been upgraded considerably for the same. the others will be out of service in the near future. There are reasons for high attrition rates for india.
1. a lot of old aicrafts. ( but we have no intentions for dragging these for more than 3-4 years.
2. no AJT's. pilots directly fly the fighters after the IJTs.
3. the high flight hours of the indian pilots.
I'll try to search for the attirition figures and post them soon.

ajaybhutani

CyberTracker,
this is the latest info on attrition rates of IAF.
http://www.bharat-rakshak.com/NEWS/n...hp?newsid=2024.

Dima

wow, when i was five, dang, i think i was still wearing a diaper when i was five, lol, thanks for being patient with me

it "eats" the radar waves, that's cool, so who's working on the radar cancellation devices?

" The speed you are going is irrelevent- what matters is that the speed relative to the emitter is zero." ohhhhhhh, that makes sense ,lol, sorry

10m to the exponent 3 equals 10m? wouldn't it equal 1,000 meters

oh, i think i got something that mentions Russia developing AESA, but you know me, probably misinterpreted it again, lol, so i'd like you to check it and give me your thoughts, very short, a link is provided as well

The corporation "Phazotron -NIIR" started the production of the basic elements of radar AESA.
Corporation "Phazotron -NIIR" completes the construction of airborne radar (BRLS) with the active impulse phased antenna cascade (AESA), reported general director - design project leader of corporation Anatoliy kanashchenkov. "The construction of radar with the impulse phased antenna cascade of the next generation will be completed in the first quarter. The antenna with a diameter of 700 mm already went into the production ", it reported A.Kanashchenkov. "Phazotron -NIIR" actively works at creation by promising BRLS AESA for the new light export- oriented strike aircraft, created on RSK "MiG", said the head of corporation. According to him, in the production of the radiating elements AESA "were outlined very positive changes". "The quadrupled module is prepared now. Naturally, as with any experimental design work, there are complexities - some elements thus far have run-away characteristics. But this problem is decided ", it said A.Kanashchenkov. According to him, the corporation proceeds with additional financial expenditures on this theme. A.Kanashchenkov it reported that the elements of radar AESA are created in the cooperation with several enterprises. "Now the technology is mastered - three firms, which participate in the project, organized the joint production, which is modernized, in order on its base to form the rule of the creation of modules", said A.Kanashchenkov. According to him, the production is created on the base of Tomsk institute "MIKRAN", with which there is a sufficiently large production, which makes the advanced means of communication. According to the data Of a.Kanashchenkov, one firm, begun to operate in the cooperation, specializes in the region of semiconductor technology, and another has a technology of the production of monolithic elements in the composition of the receiving-transmitting module. "" Phazotron -NIIR Corporation "determines the ideology of the leading and promising works", it said A.Kanashchenkov

here's the link

http://mfit.ru/defensive/obzor/ob18-02-05-2.html