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DoctorQuest

Aircraft Radar Cross Section

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I have found one parameter that specifically speaks to this: BaseRCSModifier.

 

I have been experimenting with it but is is rather inconclusive at this point.

 

Does anyone one know how to determine the actual RCS of an aircraft. (Yes, I know it varies depending on LOS from the radar, etc.)

 

I am assuming that BaseRCSModifier is used in a calculation along with the structure of the airframe to determine the final RCS.

 

Anyway, any hints or help would be appreciated.

 

Thanks.

 

KK

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Most such methods are classified. However, the rough numbers have been released for certain planes. I know the B-52 has one of the largest RCS recorded, 100 sq m or so. The B-1B's is roughly the same size as the F-16 I think, about an order of magnitude less (10 sq m?). Then you have "stealthy" (not stealth) planes like the Typhoon, F/A-18E/F, Rafale, etc that are another order of magnitude less than that (1 sq m?). Then you have the F-117 an order below those, than the F-22 and B-2 an order below THAT (the old "golf ball size"). The F-35 will likely be in the F-117 range.

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Also, the RCS varies depending on the angle from which the plane is "seen" by the radar (ie. some aircrafts are optimized to reduce RCS when seen from the front and above, while some are optimized to reduce the RCS from all angles).

 

Another interesting point is the fact that depending on the method used to obtain stealth, the RCS is not the same depending on the frequency of the radar.

 

Then you have to understand the various methods used to reduce the RCS of an aircraft, and their limits.

 

1) Using material with a low reflection

The material used in building the plane have an impact on the RCS, the classical exemple being the wooden Mosquito being naturally stealthier than its counterparts of metallic construction.

Using composite material, especially some specifically designed to enhance stealth is a simple way to partly reduce the RCS.

 

2) Hiding echo chambers and avoiding scatter points

With this method, you try to hide, reduce or remove anything that could amplify the radar signal, or redirect it indiscriminately (hiding reactors, removing a maximum of sharp angles, protrusions, draining holes).

The goal is not to eliminate or scatter the radar echo, but to avoid amplifying it.

 

3) Specifically shaping the plane to redirect the echo away from the emitting radar

Here the whole point is to avoid being seen, by adopting a shape that when hit by a radar wave, will be returned away from the emitter, making the plane "invisible".

Yet it's not that easy, with the first generation of shaping, the stealth was directionnally optimised, meant to reduce RCS only when seen from a particular angle.

The latest generation of shaped planes are more efficient and able to reduce RCS from wider angles.

But it's not perfect, as it is also optimised for some radar frequencies, and it has been demonstrated that low frequency radars coupled to large arrays of passive receiving stations (ie. one radar emits, the plane scatters the echo, but a multitude of these echoes are received bye the passive receiving stations and using triangulation, the position of the plane is determined, it has even been demonstrated using reflection of TV signal) negate most shaping.

 

4) Using Radar-Absorbent Material

Adding material to the plane designed to "trap" the radar waves is a way to reduce RCS, unfortunately, these materials are optimised for specific range of frequencies and are mostly useless against other frequencies, with some older materials, they even acted as echo chambers, amplifying and scattering the radar signal).

 

5) Actively cancelling the radar signal

Active echo cancellation, consisting of detecting the radar wave and reemitting a counter-wave to reduce or remove the echo is still not very well documented, and is a very difficult task as it needs to identify a large variety of signals and determine which signal to add to diminish or suppress the echo.

 

All these factors and the fact that real numbers on the efficiency of these methods and the way to calculate their impact makes it impossible to model in a game.

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Fubar512 has figured it out and when he gets back from his trip he can enlighten us.....him and I have some extremely detailed books on stealth.

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RCS of Su-27 15 m²

RCS of MiG-29A 15 m²

RCS of MiG-29M 1.5 m²

RCS of F-16A 3.0 m²

RCS of F-16C 1.0 m²

RCS of MiG-21 1.5 m²

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I've made a chart with the appropriate correction factors for the series. I'm presently taveling, I will post it when I return. Please be aware, however, that the current patch has damaged that feature, and the only way to acheivestealth (now), is by declaring a negative value :rolleyes:

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I've made a chart with the appropriate correction factors for the series. I'm presently taveling, I will post it when I return. Please be aware, however, that the current patch has damaged that feature, and the only way to acheivestealth (now), is by declaring a negative value :rolleyes:

 

That's what I appear to have stumbled upon. Specifying a negative BaseRCSModifier SEEMS to affect AI radar detection but when I fly against the "steathly" aircraft I can still see it on radar.

 

Is there any way to dump or display an aircraft's calculated RCS?

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If you can see it on radar, something's not right. Even a value of -0.001 renders the aircraft completely invisible to radar in-game, with all settigs on "hard".

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If you can see it on radar, something's not right. Even a value of -0.001 renders the aircraft completely invisible to radar in-game, with all settigs on "hard".

 

Crap.

 

That was it. Wrong radar setting. You learn something new every day.....

 

Thanks, Fubar.

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BaseRCSModifier editing does good for sam, enemy a-a, enemy aircraft, etc, but why could i still lock on to my wingman(with edited rcs)?

hmm.

 

Because you probably don't know what you're doing? :rolleyes:

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RCS of Su-27 15 m²

RCS of MiG-29A 15 m²

RCS of MiG-29M 1.5 m²

RCS of F-16A 3.0 m²

RCS of F-16C 1.0 m²

RCS of MiG-21 1.5 m²

 

Any idea why the F16C has only 1/3 the RCS of the 99% identical A modell ????

 

Aju,

 

Derk :dntknw:

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Probably :

 

1) Greater use of composite materials

2) Changes in the position and size of maintenance traps, draining holes, etc...

3) Changes in the canopy better isolating the cockpit, avoiding to have it acting as an echo chamber

4) Propaganda

 

Since most of these modifications were already included in Block 15/20, propaganda might account for a large part of the difference, unless the C include some RAM, which would be surprising given the maintenance needed for the generation of RAM available at the time.

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Probably :

 

1) Greater use of composite materials

2) Changes in the position and size of maintenance traps, draining holes, etc...

3) Changes in the canopy better isolating the cockpit, avoiding to have it acting as an echo chamber

4) Propaganda

 

Since most of these modifications were already included in Block 15/20, propaganda might account for a large part of the difference, unless the C include some RAM, which would be surprising given the maintenance needed for the generation of RAM available at the time.

 

The goldplated canopy (in order to eliminate the cockpit radar trap) certainly was incorporated in Block 15 cq retrofitted to earlier Blocks . RAM materials were retrofitted (AFAIK) into the engine intake and for the rest I cannot imagine any significant difference between the A and C models, apart from the bigger C intake and tailbase (apart from the extended taibase for the brake chute), that might actually increase the RCS of the C from certain aspects.....

In connection with the use of night vision goggles the clear canopies are being "reretrofitted" by the way, but that goes for both models.......

 

Aju,

 

Derk :wink:

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I think it was the gold plated canopy that made the big difference.

 

However, just look at the differences in the 2 Fulcrum models. A factor of 10!

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BaseRCSModifier editing does good for sam, enemy a-a, enemy aircraft, etc, but why could i still lock on to my wingman(with edited rcs)?

hmm.

 

Check your radar difficulty setting. It appears to affect how easy it is to "see" stealthy targets.

 

Also keep in mind (from previous posts) that patches have affected the way BaseRCSModifier is used. You may need to use a negative number to achieve stealth.

Edited by kirbykern

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Any idea why the F16C has only 1/3 the RCS of the 99% identical A model ????

 

Aju,

 

Derk :dntknw:

 

OK,

 

Let's use another case to explain this, the B-1A versus the B-1B.

 

The B-1A has an RCS equivalent* to 10 square meters. whereas the B-1B's RCS is equivalent to less than 1 square meter. Two of the obvious differences between the two, are the removal of the A's dorsal spine, and the redesign of the inlets on the B. And that was a redesign that took place during the early 1980s. Obviously, the science of "stealth" has advanced quite a bit since then.

 

*It is somewhat incorrect to say "The FXYZ-100 has an RCS of .8 square meters..." The proper terminology is " The FXYZ-100 has an RCS equivalent to XX.X square meters", as the standard unit of measure is based on a flat surface oriented towards the x-mitter. Also, most of these figures are based on frontal aspect RCS, not whole-body RCS. An F-105, for example, may appear to be as big as a house when seen on a radar from a side-aspect, yet head on, it presents a smaller RCS than does a MiG-21!

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Because you probably don't know what you're doing? :rolleyes:

 

i was cheking it ou on my wingie, on an rcs=-0.0012

 

i still detect him.

 

is there a technology out there in RL that makes friendly stealth units visible to other friendlies?

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i was cheking it ou on my wingie, on an rcs=-0.0012

 

i still detect him.

 

is there a technology out there in RL that makes friendly stealth units visible to other friendlies?

 

Did you declare it as "BaseRCSModifier=-0.0012", under the detect system section in the data.ini? If so, there is no way that you should see his return on a radar screen, with the options set to hard.

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In peacetime they will put transponders on the outside of the plane to boost their RCS as well as preserve the info of what they look like on radar WITHOUT them.

The only other way is the use of datalinks.

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In peacetime they will put transponders on the outside of the plane to boost their RCS as well as preserve the info of what they look like on radar WITHOUT them.

The only other way is the use of datalinks.

 

Stealth is nothing more than a method of controlling the scattering of radar waves away from the aircraft so as to minimize its return....a powerful enough radar will still see it at some point. The trick is to minimize that by flying a profile that further reduces the chances of detection (ie, low level in the ground clutter).

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Did you declare it as "BaseRCSModifier=-0.0012", under the detect system section in the data.ini? If so, there is no way that you should see his return on a radar screen, with the options set to hard.

 

 

hmm..

 

weird.....

 

well, it works against those pesky shilka and everything else.

 

its always nice to sneak up on the enemy's 6'0clock low, lol when you see their faces when they realize it is too damn late for evasive ACM.

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hmm..

 

weird.....

 

well, it works against those pesky shilka and everything else.

 

its always nice to sneak up on the enemy's 6'0clock low, lol when you see their faces when they realize it is too damn late for evasive ACM.

 

Ahhhh, you do realize that stealth does nothing for you if your opponent's radar is "pointing" the other way, right? And that without the aforementioned parameters declared exactly as I mentioned, you're flying with nothing more than "placebo" stealth? :rolleyes:

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