The F-35 versus Irans S-300s

[milosh]

Serbian shot down was a combination of things which would be very difficult to replicate with reliability.

Just a reminder:
1. Flying the same route multiple times allows the SAM site to set a trap.
2. The F-117 flew directly towards the SAM after prosecuting the target.
3. The F-117 had no RWR to alert him that the was being tracked.
4. The F-117 was only 8nm away when the SAM took him down.

Item of note, even though the SAM was only 8nm away and the F-117 was flying straight & level, both of the missiles shot at him missed and only one of them detonated above him due to the SAM's proximity sensor detecting the F-117.

SAM crew never mentioned something like that but they talk how many time they changed position because of safety.

[hornetfinn]

I think milosh is correct here that there was no trap set up. From what've read about the incident from Serbian sources, I gather the following:

1. S-125 Pechora crew was operating with their regular tactics which meant staying in one place only for limited time and being as mobile as possible. This is commendable as Pechora is not the most mobile system in the world.

2. Pechora crew was always operating in disciplined way and only radiated for short interwals with their radars to counter Wild Weasels and jamming systems.

3. Pechora crew relied on VHF P-18 radar to give early warning about enemy aircraft. Very low frequency meant that it was impossible to kill with HARM missiles (no space for large enough antenna in missiles) and it was also difficult to pinpoint by other assets due to low frequency. This allowed it to operate for much longer periods of time than higher frequency radars. Downside is that it could only give rough information about target position, heading and speed and could not tell target altitude or type. Of course it could also be pretty easily jammed due to narrow bandwidth available at that low frequency.

4. Pechora crew had no prior knowledge about incoming F-117 and did not set up a trap specifically against it. They did set up a trap to catch any Coalition aircraft flying within their range. Looking at map the position was very normal firing position for SAM system protecting high value target (like Belgrade area in this case).

5. I said earlier Sebs detected the F-117 at 50-60 km, but it seems like P-18 radar could detect the F-117 only at 23 km away accoridng to Serbians.

6. They apparently had quite a bit of trouble getting a lock on to it with fire control radar and only managed to do it after couple of failed attempts to do it

7. Serbians had no idea it actually was an F-117 as they had no means if ID'ing it and just detected a target and engaged it.

8. F-117 was more like a manned cruise missile which follows a predetermined route for the most part. This means that a SAM system that was not known to be in the area happened to be in the right spot at the right time could shoot it down pretty easily as the F-117 could not do anything about it and could not have any warning about such a threat. The shoot down incident clearly shows that it happened in this case. F-117 would be very vulnerable to modern mobile systems if well employed. F-35, F-22 and B-2 are nothing like that.

[uclass]

The Serbian SA-3 locked and shot the F-117 down WVR. It accomplished nothing an A-10 (no radar) with sidewinders couldn't have accomplished if it had chanced upon the same opportunity.

http://thediplomat.com/2014/08/the-f-35 ... hf-threat/

Electromagnetic radiation is known to scatter from bodies smaller than its wavelength. This phenomenon, known as Rayleigh scattering, is often used by F-35 critics to point out that the aircraft could be detected by enemy radar operating in the VHF range, given that some of the aircraft’s geometrical features such as the wing and elevator edges are smaller than the 1-3 meter wavelength within which such radars typically operate. Reportedly, this is also how Colonel Zoltan Dani, then commander of the 3rd Battery of the Federal Republic of Yugoslavia’s 250th Air Missile Defense Brigade, managed to detect, and later down, Lt. Col. Zelko’s plane. According to The Aviationist, a series of in-field modifications carried out by the Yugoslavs further reduced the frequency of the 1960s vintage P-18 VHF acquisition radar under Dani’s command, which enabled his men to detect Zelko’s F-117 at a distance of 30 to 37 miles (50-60 km).

Because of their relatively long wavelength, VHF radars generally lack sufficient accuracy to guide a missile to a target on their own and are therefore used to cue higher frequency, shorter wavelength engagement radars to the approximate location of the target. Narrowband stealth aircraft such as the F-117, F-22 and F-35 were designed to be very low observable (VLO) in these higher frequencies in order to significantly limit the range at which they can be successfully detected by engagement radars. Consequently, despite inputs from the VHF acquisition radar, the X-band* engagement radar of Dani’s SA-3 battery was able to track the F-117 only at a distance of 8 miles (13 km), obtaining a lock and launching two missiles towards it only on the third attempt (the colonel would order his men to switch the engagement radar on for no more than 20 seconds for each attempt in order to avoid being targeted by NATO electronic warfare aircraft).

Nobody ever claimed stealth aircraft were stealthy inside visual range.

[uclass]

Interesting chart. Some ships are more stealthy then others. A DDG-51 has the RCS of a small trawler. When they talk about fighter sized targets being in 1-10 sq. M I guess they mean an SU-30, or F-15? I've read on this board that the F-18E/F is closer too the 0.1 range at least from the front. So Superman is just below 0.1? Now I'm surprised they rate the F-22, F-117, F-35 all far below insects. I thought the F-22 was rated as a metel Marbel, which would be bigger then an insect, though metal would be more reflective then tissue.

So if our stealth aircraft show up as such small objects what effect would weather have on radar? The old UHF/VHF of WWII were effected by rain, which caused clutter, or echoes. These are the kinds of radars that are supposed to be able to detect stealth. Could an F-35 be confussed with rain drops, or would a pulse dopler radar be able to filter it out? Would this mean that it's much harder to detect a stealth aircraft in rain, or snow, or do I have it wrong? Thank you in advance Radar experts.

In truth it's a very large insect. The vast majority of insects bar stuff like locusts have a lower RCS than 0.001m^2, however a desert locust measures in at a whopping 0.003m^2 or 32cm^2.

https://dspace.lib.cranfield.ac.uk/bits ... e_2006.pdf

A clean F-18E/F is 0.1m^2 from the front but a clean F-18E/F isn't particularly useful. The figure quoted is for a loaded one.

There is a theory that rain actually makes detection easier and it was raining when Dale Zelko's F-117 got shot down.

VHF/UHF radars can detect stealth better but they aren't much good for targeting, they tell you that something is roughly about there in the sky. Contrary to popular opinion this is more to do with reduced attenuation characteristics for longer wavelengths, since the Mie region effects that people often attribute may be either positive or negative and cause a variance in effective RCS by only about a factor of 4 from the optical region RCS, which only leads to a range detection alteration of about +41% (4^[0.25]) or -29% (0.25^[0.25]) depending on where you land. Accurate stealth aircraft RCSs are always kept secret for this reason, to prevent radar wavelength optimisation. And as you can see if you get too silly with long wavelengths, then the affect on range is very bad.

http://www.radartutorial.eu/01.basics/R ... ng.en.html



You can make some first order estimations about F-22 detection and engagement range for the S-400 MW class radars based on the stated performance of the Irbis-E and the F-117 shootdown incident, noting that the Irbis-E is 20kW and the SA-3 VHF detection and X-Band engagement radars are 380kW and 250kW respectively.

http://www.niip.ru/index.php?option=com ... 6&Itemid=8
https://en.wikipedia.org/wiki/S-125_Neva/Pechora#Radars

1. Detection range: [(1000/20)^(1/4)]x26.6km = 71km

2. http://thediplomat.com/2014/08/the-f-35-vs-the-vhf-threat/

Detection range: [(1000/380)^(1/4)]x50km = 64km, [(1000/380)^(1/4)]x60km = 76km

3. Engagement range: [(1000/250)^(1/4)]x13km = 18.4km. This is based on larger RCS F-117, with no EW, but we'll assume that is counteracted by having better radar processing for the S-400

So we see detection range falling out at 64-80km and engagement range coming out circa 20km, which is roughly what the aviationweek analysis showed.

However based on a claimed RCS of 0.0001m^2, using Pi*r^2, you get an r value of 0.0056m. So for a VHF 1m wave, this puts the r/wavelength value at 0.0056, which puts you deep in the Rayleigh region, which is very bad for detection range. However, using a 0.3m UHF wave, you would end up on the peak labelled 'A' in the graph.

However for an F-117, RCS 0.005,^2, you get an r value of 0.0126m, so a 1m VHF wave gives the r/wavelength value as 0.0126, which again places you near the peak at A. However the 0.3m UHF wave puts you at 0.042, which is roughly at the next trough after B in the graph.

So theoretically the UHF 0.3m wave triples effective F-22 RCS to 0.0003m^2 (still not very useful) yet reduces effective F-117 RCS to 0.000166m^2, whereas the 1m VHF wave has the effect of tripling F-117 RCS but effectively makes the F-22 completely disappear (~100 fold reduction in RCS)!

[uclass]

Serbian shot down was a combination of things which would be very difficult to replicate with reliability.

Just a reminder:
1. Flying the same route multiple times allows the SAM site to set a trap.
2. The F-117 flew directly towards the SAM after prosecuting the target.
3. The F-117 had no RWR to alert him that the was being tracked.
4. The F-117 was only 8nm away when the SAM took him down.

Item of note, even though the SAM was only 8nm away and the F-117 was flying straight & level, both of the missiles shot at him missed and only one of them detonated above him due to the SAM's proximity sensor detecting the F-117.

He was only 8 miles away, not nm. It was a WVR shot.

https://theaviationist.com/2014/03/27/v ... shot-down/

[castlebravo]

Interesting chart. Some ships are more stealthy then others. A DDG-51 has the RCS of a small trawler. When they talk about fighter sized targets being in 1-10 sq. M I guess they mean an SU-30, or F-15? I've read on this board that the F-18E/F is closer too the 0.1 range at least from the front. So Superman is just below 0.1? Now I'm surprised they rate the F-22, F-117, F-35 all far below insects. I thought the F-22 was rated as a metel Marbel, which would be bigger then an insect, though metal would be more reflective then tissue.

So if our stealth aircraft show up as such small objects what effect would weather have on radar? The old UHF/VHF of WWII were effected by rain, which caused clutter, or echoes. These are the kinds of radars that are supposed to be able to detect stealth. Could an F-35 be confussed with rain drops, or would a pulse dopler radar be able to filter it out? Would this mean that it's much harder to detect a stealth aircraft in rain, or snow, or do I have it wrong? Thank you in advance Radar experts.

In truth it's a very large insect. The vast majority of insects bar stuff like locusts have a lower RCS than 0.001m^2, however a desert locust measures in at a whopping 0.003m^2 or 32cm^2.

https://dspace.lib.cranfield.ac.uk/bits ... e_2006.pdf

A clean F-18E/F is 0.1m^2 from the front but a clean F-18E/F isn't particularly useful. The figure quoted is for a loaded one.

There is a theory that rain actually makes detection easier and it was raining when Dale Zelko's F-117 got shot down.

VHF/UHF radars can detect stealth better but they aren't much good for targeting, they tell you that something is roughly about there in the sky. Contrary to popular opinion this is more to do with reduced attenuation characteristics for longer wavelengths, since the Mie region effects that people often attribute may be either positive or negative and cause a variance in effective RCS by only about a factor of 4 from the optical region RCS, which only leads to a range detection alteration of about +41% (4^[0.25]) or -29% (0.25^[0.25]) depending on where you land. Accurate stealth aircraft RCSs are always kept secret for this reason, to prevent radar wavelength optimisation. And as you can see if you get too silly with long wavelengths, then the affect on range is very bad.

http://www.radartutorial.eu/01.basics/R ... ng.en.html



You can make some first order estimations about F-22 detection and engagement range for the S-400 MW class radars based on the stated performance of the Irbis-E and the F-117 shootdown incident, noting that the Irbis-E is 20kW and the SA-3 VHF detection and X-Band engagement radars are 380kW and 250kW respectively.

http://www.niip.ru/index.php?option=com ... 6&Itemid=8
https://en.wikipedia.org/wiki/S-125_Neva/Pechora#Radars

1. Detection range: [(1000/20)^(1/4)]x26.6km = 71km

2. http://thediplomat.com/2014/08/the-f-35-vs-the-vhf-threat/

Detection range: [(1000/380)^(1/4)]x50km = 64km, [(1000/380)^(1/4)]x60km = 76km

3. Engagement range: [(1000/250)^(1/4)]x13km = 18.4km. This is based on larger RCS F-117, with no EW, but we'll assume that is counteracted by having better radar processing for the S-400

So we see detection range falling out at 64-80km and engagement range coming out circa 20km, which is roughly what the aviationweek analysis showed.

However based on a claimed RCS of 0.0001m^2, using Pi*r^2, you get an r value of 0.0056m. So for a VHF 1m wave, this puts the r/wavelength value at 0.0056, which puts you deep in the Rayleigh region, which is very bad for detection range. However, using a 0.3m UHF wave, you would end up on the peak labelled 'A' in the graph.

However for an F-117, RCS 0.005,^2, you get an r value of 0.0126m, so a 1m VHF wave gives the r/wavelength value as 0.0126, which again places you near the peak at A. However the 0.3m UHF wave puts you at 0.042, which is roughly at the next trough after B in the graph.

So theoretically the UHF 0.3m wave triples effective F-22 RCS to 0.0003m^2 (still not very useful) yet reduces effective F-117 RCS to 0.000166m^2, whereas the 1m VHF wave has the effect of tripling F-117 RCS but effectively makes the F-22 completely disappear (~100 fold reduction in RCS)!

The thing about VHF radars is that they are claimed to defeat VLO shaping to some degree, so a 1m+ wavelength radar striking an F-22 should reflect energy closer to that of a Raptor sized sphere without VLO treatment rather than a 0.0015m^2 sphere. The detection range will of course vary depending on where the ratio of wavelength to target RCS at that wavelength falls on your chart (longer range at peak, less range at trough), but the increase in RCS for small VLO aircraft facing long-wave radars is a separate matter.

[uclass]

The thing about VHF radars is that they are claimed to defeat VLO shaping to some degree, so a 1m+ wavelength radar striking an F-22 should reflect energy closer to that of a Raptor sized sphere without VLO treatment rather than a 0.0015m^2 sphere. The detection range will of course vary depending on where the ratio of wavelength to target RCS at that wavelength falls on your chart (longer range at peak, less range at trough), but the increase in RCS for small VLO aircraft facing long-wave radars is a separate matter.

It's a falsehood. There is some resonance in the Mie region for certain frequency values depending on the effective r/wavelength value and longer wavelengths are attenuated less but they are still affected by geometry. Think about this. A standard P-18 radar could only detect an F-117 at 23km, the modified Serbian P-15 380kW radar only managed to detect one at 50km.

http://thediplomat.com/2014/08/the-f-35 ... hf-threat/

That's an aircraft supposedly 5 times bigger in RCS than an F-22. Now you're saying it appears as an aircraft sized sphere, implying that the 380kW VHF radar can only detect a several m^2 sphere at 50km. Now the stated figure is in fact 150km for the early 270kW version and 250km for the later 380kW for such a large object. So the F-117 achieved a 5 fold reduction in detection range, which requires a 625 fold reduction in RCS. Now 0.0005m2 is a 2000 fold claimed reduction, but by hitting the right point in the Mie region, they could triple or quadruple the effective RCS to 0.0015-0.002m^2.

Much higher frequency EM waves are able to detect miniscule objects but they have useless distance properties, e.g. optical region. IR is better but still struggles.

[arian]

Right, when they say "anti-stealth" radar they don't mean it can detect VLO targets at extreme ranges, as they would regular targets, but rather that they are not so useless against VLO targets as higher frequency radars. You're still going to get big degradation in detection range

[MD]

Just a reminder:
1. Flying the same route multiple times allows the SAM site to set a trap.
2. The F-117 flew directly towards the SAM after prosecuting the target.
3. The F-117 had no RWR to alert him that the was being tracked.
4. The F-117 was only 8nm away when the SAM took him down.

Item of note, even though the SAM was only 8nm away and the F-117 was flying straight & level, both of the missiles shot at him missed and only one of them detonated above him due to the SAM's proximity sensor detecting the F-117.

Just a note, that going towards or away from a SAM site and most especially its radars, isn't necessarily indicative of something bad. It all depends on how the mission was planned and what the RCS was believed to be based on the known threat, based on that planning. There are times you may do either, or both. That's about as general as I can explain that.

[MD]

Exactly. Compared to F-35, F-117 was a sitting duck if enemy managed to engage it. It had nothing to show it was being tracked by radar system or warn about radar systems in the area. It had nothing to tell it was being engaged. Even if it did, it had no performance and maneuverability to do anything about it.

The only warning about radar systems or threats in the area, would be if something was picked up on the internal UHF, which would be on threat warning freq. However the comm set had short range when on internal, versus when the normal comm antennae were extended.

Neither it had any countermeasures systems (ECM, chaff, decoys) to make it more difficult to hit.

The 117 isn't completely defenseless. I'll leave it at that.

[MD]

I think problem at the time it was designed was designing antennas that would not increase RCS significantly. Even if such antennas were available, installing them to F-117 might've been pretty problematic. How they'd work with RAM and radar absorbing paint for example?

Correct. But moreso due to the major RCS increase the antennae would cause in interrupting the fuselage shape , vice any problem with the RAM coating itself. RAM wouldn't be able to take care of the antenna protrusion problem for any RWR antennas at the time.

As Basher quoted me here in his post:

[MD]
The F-117 never had an RWR because it wasn't feasible to install one. There was no way to on the exterior to have the required sensor "nubs", without affecting the shape of the exterior and thus raising the RCS tremendously. So it was left off. That's why the F-117 has radar reflectors on the sides of the aircraft when flying stateside, so that there's an interruption of the shape allowing air traffic control to at least get a primary radar return. Otherwise if the IFF failed, they couldn't see us. For combat, these were removed, as were the rotating red beacon lights, with their attachment points faired over and covered in RAM.

Unofficially, the AF didn't want an RWR in the 117, because in theory, it should never show anything other than radars in search mode, it should never show a lock by a target tracking radar. Because if it did, well.....then the technology would be shite and garbage, so we the pilots would feel.

Additionally, it wasn't desired to have pilots reacting to RWR indications, as the mission planning in a 117 (without getting into too much detail) is precise enough that it's optimized for flying the planned black line routing, so to speak, and not wandering off course or being tempted to by reacting to an RWR.

[MD]

8. F-117 was more like a manned cruise missile which follows a predetermined route for the most part. This means that a SAM system that was not known to be in the area happened to be in the right spot at the right time could shoot it down pretty easily as the F-117 could not do anything about it and could not have any warning about such a threat. The shoot down incident clearly shows that it happened in this case. F-117 would be very vulnerable to modern mobile systems if well employed. F-35, F-22 and B-2 are nothing like that.

The threat laydown regarding fixed, and some mobile threats, was known; however we got careless. Ironic that the Serbs learned to not constantly transmit with their search/track radars, yet we failed to learn not to be lazy with mission planning; both of which were important Vietnam lessons.

Indeed a 117 would've had some vulnerability to mobile systems, as mobile systems weren't considered in mission planning. Namely because they're mobile and couldn't be planned around. So fixed systems were planned and flown against, based on the laydown. Since then, we've come a long way in mission planning with the new/newer stealth aircraft, which have far less vulnerabilities.

[hornetfinn]

From Serbian F-117 shoot down we can take couple of lessons learned:

A. Low frequecy radars are not any kind of magical device in detecting stealth aircraft. They can detect and track VLO aircraft at longer ranges than higher frequency radars, but are still degraded a lot (several times) compared to detecting non-stealthy aircraft.

B. Higher frequency engagement radars will still need to detect and track the target themselves and their performance is seriously degraded compared to how far away they can detect and track non-stealthy aircraft.

F-117 was totally reliant on stealth, reconnaissance of threat systems and mission planning. Enemy could easily catch it if their defensive systems were not detected beforehand and if they managed to be at the right place at the right time. If F-117 was detected and tracked by fire control radar, then it was totally out of luck. There was just nothing it could do to any threat that could engage it. F-35 is totally different animal as it has all the systems in the world to detect, identify and engage threat systems no matter what the situation. It also has the performance and wide variety of long ranged weapons to back these systems up if something unexpected happens.

S-300 would be a dangerous system against F-117 as it's highly mobile and has powerful sensors and missiles. Too bad F-117 is already retired and F-35 only shares stealth qualities with it. Of course S-300 might be able to shoot down some F-35 if they were used in highly mobile way and managed to be at the right place at the right time to detect and engage F-35. That however would be true to any SAM system in the world. However I doubt the S-300 system would live very long as the buddies of that F-35 would likely very quickly kill that S-300 system.

[hornetfinn]

8. F-117 was more like a manned cruise missile which follows a predetermined route for the most part. This means that a SAM system that was not known to be in the area happened to be in the right spot at the right time could shoot it down pretty easily as the F-117 could not do anything about it and could not have any warning about such a threat. The shoot down incident clearly shows that it happened in this case. F-117 would be very vulnerable to modern mobile systems if well employed. F-35, F-22 and B-2 are nothing like that.

The threat laydown regarding fixed, and some mobile threats, was known; however we got careless. Ironic that the Serbs learned to not constantly transmit with their search/track radars, yet we failed to learn not to be lazy with mission planning; both of which were important Vietnam lessons.

Indeed a 117 would've had some vulnerability to mobile systems, as mobile systems weren't considered in mission planning. Namely because they're mobile and couldn't be planned around. So fixed systems were planned and flown against, based on the laydown. Since then, we've come a long way in mission planning with the new/newer stealth aircraft, which have far less vulnerabilities.

Thank you a lot MD for your comments, really appreciated! It seems like theory and practice concur in the case of stealth and F-117 in particular.

I think it's really remarkable what F-117 managed to do with basically just stealth features ensuring survivability. Sure it might've had some extra tricks up in its sleeve, but nothing like what F-35 or even most 4th gen fighters have. It must've been hell of an experience flying first time to Badghdad in 1991 for example. I find it amazing that only one has ever been shot down.

[MD]

Thank you a lot MD for your comments, really appreciated! It seems like theory and practice concur in the case of stealth and F-117 in particular.

I think it's really remarkable what F-117 managed to do with basically just stealth features ensuring survivability. Sure it might've had some extra tricks up in its sleeve, but nothing like what F-35 or even most 4th gen fighters have. It must've been hell of an experience flying first time to Badghdad in 1991 for example. I find it amazing that only one has ever been shot down.

Happy to be able to add useful info.

It's indeed amazing what we've done, and where we've now come, when it comes to stealth. The 117 was revolutionary. But like with anything, has been surpassed by technology, both in stealth technology as well as in enemy defenses. However the groundwork laid down by that program, and what it has enabled us to have today in the F-35, is nothing short of amazing. And we still don't likely know the true extent of the capabilities of the F-35 and how effective it can truly be. Heck, when the B-2 and F-22 came out, they were remarkable in comparison to the 117. The 117 is maybe around 25% as capable as the F-35 is turning out to be, and may even turn out to be less as time goes on. But the 117 saw its day, and by the time of its retirement, it had served well, and it was time. Threats surpassing its capabilities to manage, as well as maintenance man hours per flight hour that were rivaling the F-111; coupled with the F-22 coming online, made for its final sundown.

For the guys that went downtown in '91, it was indeed a heck of a time, for no one truly knew if "this stealth crap" actually worked. Sure, there was testing and some numbers and even going against some older gen threat systems, but actual war and actual employment is something else altogether. Most of our ground instructors were guys from the black days of the program, early-mid 80s and who did the '91 war. Some of the stories were nothing short of amazing. Such as one guy headed into his target. In the 117, the pilot spends alot of time heads down in the IRADS when getting close to the target area, in order to acquire, ID, and track the target and eventually the DMPI. Cruising in, all lights are off, and the cockpit lighting is dimmed down to nearly nothing. In fact, much of the light you get at this time is terrestrial lighting off of stars, the moon, etc, depending on the illum level of that particular night. There was a little bit this night, and this particular pilot was heads down doing his his target search, with the jet on autopilot and flying it's preplanned routing. What little illumination there was in the surrounding space, all of a sudden seemed to turn to a shadow, and the pilot looks up. Just as he looks up, he sees two Iraqi MiG-29s about 100 ft above him, crossing right to left as he passes nearly underneath them by 100 or so feet. So close that he could see the Iraqi pilots in their cockpits illuminated by their cockpit lighting. Bouncing in their wake, he continued on his northerly heading, as they disappeared into the darkness on their westbound heading. Assuming the MiGs were searching air-air, they didn't detect the 117 and were unaware of the near midair; which in itself would be an unfortunate way to lose a 117. The 117 force made a very good showing, but after about a week or so, their job was done. Same with OIF in 2003. Once the door was kicked in and the IADS taken down, there wasn't any need for the 117s with their limited and specialized capabilities, and high maintenance requirements. Now with the F-35 and its wealth of capabilities, that will no longer be the case. It will be very interesting to see where this capability grows to.