Can onboard radar pick up air-to-air missiles?

[Cmptohocah]

Might be a stupid question, but I was wondering: would a typical fighter radar be able to pick up any trace of missiles being launched at it? Or would those "targets" be to small to be registered?

I know that in their interview, a crew of S-125 Neva/Pechora battery mentioned that they could actually see on their radar screen parts of the airplane they just hit, separating away so it got me thinking in this direction.


 

[Bricux]

I researched this topic for my Wing. From big Russian SAMs, "earliest" system that can successfully detect and fight with enemy missiles (smaller than cruise missiles, eg HARM) is SA-17 Buk-M1-2.

With materials witch I found we can tell that SA-11 Buk-M1 (we have it in DCS) can't successfully detect and fight with objects HARM size (so AIM-120 also). If  SA-11 can't, SA-6, SA-5, SA-3 and SA-2 can't either. 

About that parts of airplane compare size (RCS) of a wing witch fell of from a plane with eg size of AIM120 or AGM88.

Edited February 10, 2022 by Bricux

[Hiob]

Debris like wings and stabilizers departing from a hit aircraft have a much larger radar cross section than a slim missile pointing at you.

As always with radar it strongly depends on range. The amount of energy that hits the object and can potentially be reflected growth/shrinks to the power of 3 with range.

Possible in theory - yes, but with a lot of asterisks probably.

[LetMePickThat]

1 hour ago, Bricux said:

I researched this topic for my Wing. From big Russian SAMs, "earliest" system that can successfully detect and fight with enemy missiles (smaller than cruise missiles, eg HARM) is SA-17 Buk-M1-2.

This is not true. The SA-15 was designed specifically for counter-PGM operations, incuding weapons like the Maverick, the HARM and the Alarm, and was introduced in 1983. The M1-2 reached IOC in 1998. The SA-19, introduced in 1982, also had some limited capabilities against subsonic air-to-ground weapons like the Mav'.

 

1 hour ago, Hiob said:

Debris like wings and stabilizers departing from a hit aircraft have a much larger radar cross section than a slim missile pointing at you.

True, but RCS is only part of the equation. A doppler radar will likely work better on a small RCS object moving at really high speed than on a free-falling object of relatively large size and low speed. Discrimination would also play in the missile's favor, since it would not be part of a cloud of debris and would be the only object in the radar's field of vision.

 

1 hour ago, Hiob said:

As always with radar it strongly depends on range. The amount of energy that hits the object and can potentially be reflected growth/shrinks to the power of 3 with range.

Completely true, if a missile lock is possible, it can only be achieved at short range.

1 hour ago, Hiob said:

Possible in theory - yes, but with a lot of asterisks probably.

In DCS, both the F-14 and the Mirage 2000C can achieve radar locks on incoming missiles. This screwed me a few time since my radar would rather auto-lock on the missile coming at me rather than on the bogey behind it.

Edited February 10, 2022 by LetMePickThat

[Bricux]

@LetMePickThat that's why I wrote "From big Russian SAMs"

I do not count SA-15 as big SAM like SA-6, SA-11 or SA-10. It's different class. Fact that SA-15 was designed especially for intercepting small objects like AGM88 etc. is true.

And remember that first versions of SA-15 from '83 wasn't as effective as later M1, M2 versions.

Edited February 10, 2022 by Bricux

[LetMePickThat]

7 minutes ago, Bricux said:

@LetMePickThat that's why I wrote "From big Russian SAMs"

I do not count SA-15 as big SAM like SA-6, SA-11 or SA-10. It's different class. Fact that SA-15 was designed especially for intercepting small objects like AGM88 etc. is true.

 

The SA-3 you mentionned has a similar range vs. maneuverable targets, and the SA-6/11/17 are medium-range SAMs, not the same category as the SA-10/20 and SA-12/23. Now that I think about it, the SA-12/S-300V (1983) was also designed to intercept low-RCS PGWs, a byproduct of its intended triple role (conventional anti-air defense, counter-CM missions and SRBM defense). Anyway, the original topic was about fighter radar.

Edited February 10, 2022 by LetMePickThat

[okopanja]

If the SA-125 is able to detect the F-117 and guide rocket to it, likely it can detect objects with higher RCS...

I think most people forget that back in the time when these systems were designed, detection of small objects was not desired in favor of airplanes with larger RCS, so many of them will simply drop the target to remove the unwanted reflections.

Its all about the reception of reflected signal.

When it comes to ability to actually intercept such target it is something else. E.g. how much it takes to track and launch,  will the rocket maneuver enough, will it proxy fuse or not?

You know, practical things...

[LetMePickThat]

1 hour ago, okopanja said:

If the SA-125 is able to detect the F-117 and guide rocket to it, likely it can detect objects with higher RCS...

That's far from a given. The S-125 used was modified specifically to enhance  its capabilities versus the F-117, and the plane was a relatively slow mover compared to a missile. The fact that the flight path of the F-117 was known in advance also considerably helped, and the crew had quite some time (minutes, vs. seconds in the case of a missile) to initiate a track and manually fine-tune the radar on the fly.

1 hour ago, okopanja said:

I think most people forget that back in the time when these systems were designed, detection of small objects was not desired in favor of airplanes with larger RCS, so many of them will simply drop the target to remove the unwanted reflections.

On the SA-1/2/3, it is up to the operators to choose the level of de-noising and clutter suppression filters they want. You could perfectly display raw data with zero clutter suppression if you were trying to track/lock a low RCS target flying high above the ground clutter.

1 hour ago, okopanja said:

Its all about the reception of reflected signal.

Partially. You can get a very strong signal from an object yet discard it because it doesn't meet other requirements like relative speed (measured by doppler shift), range, or azimuth resolution. 

1 hour ago, okopanja said:

When it comes to ability to actually intercept such target it is something else. E.g. how much it takes to track and launch,  will the rocket maneuver enough, will it proxy fuse or not?

You know, practical things...

I agree. This is precisely why counter-PGM systems like the SA-15/19/22 rely heavily on automation, and why such systems became practical only when phased arrays and solid state electronics had matured enough.

[GGTharos]

On 2/10/2022 at 3:37 AM, Cmptohocah said:

Might be a stupid question, but I was wondering: would a typical fighter radar be able to pick up any trace of missiles being launched at it? Or would those "targets" be to small to be registered?

I know that in their interview, a crew of S-125 Neva/Pechora battery mentioned that they could actually see on their radar screen parts of the airplane they just hit, separating away so it got me thinking in this direction.

Watching payload (or pieces of an aircraft) separate on the video of the tracked target (radar video, not visual) is very different from picking up the weapon in free flight after it has separated.

[Hiob]

Mover talked in his show with a fellow pilot about attacking drones with fighter jets and they mentioned, that it would probably very hard to find them due to their small size (and radar cross section). That would indicate that a missile is probably close to impossible to pick up….

[GGTharos]

These drones aren't likely to be harder to pick up than a cruise missile.   They might be easier to hide in a notch due to their speed but overall, they're not indicative of anything at all with respect to detecting and tracking a missile.   Construction, orientation and speed all matter.