Tuesday, July 17, 2007

The S-75 SAM System: A Site Analysis


The S-75 (SA-2 GUIDLEINE) SAM system was developed in the USSR to provide a semi-mobile, widely deployable SAM system to complement the S-25 system in place around Moscow. Deploying the S-25 nationwide would have proved to be cost-prohibitive, so a smaller, more compact, and therefore cheaper SAM system was needed for air defense across the USSR and the Warsaw Pact member states. The S-75 remains in widespread use to this day, a testament to the robust design and capability of this Cold-War era SAM system. Chinese-produced derivatives share the same deployment layouts, a testament to their S-75 heritage, and are designated HQ-2.


The S-75 SAM system is a two-stage strategic SAM system. The command-guided V-750 missiles have a 195 kg HE fragmentation warhead. Ranges vary from variant to variant, with a maximum of between 30 and 67 kilometers. Minimum ranges are as little as 6 kilometers. Altitudes range from a minimum of as little as 100 meters to a maximum of 30,000 meters, depending on the variant. Target engagement functions are handled by the RSN-75 (FAN SONG) radar set, an E or G band system with a range of up to 145 kilometers, depending on the specific model, and a cpaability to engage a single target at a time.

In an interesting footnote, the initial designator for the RSN-75 radar in the West was FRUIT SET, as evidenced by declassified CIA documentation from 1961 (NIE 11-5-6, available online at the CIA's FOIA website). No reason has yet been discerned for the change to FAN SONG.


S-75 SAM sites are relatively easy to identify on high-resolution imagery. S-75 components are typically arranged in a circular pattern. The RSN-75 engagement radar is positioned in the center of the site, typically atop a large service and command bunker, and there are six launch rails for the V-750 missiles positioned in a circular pattern facing outward around the radar position. The V-750 missiles are between 10.6 and 11.2 meters in length, depending on the variant. The launch rails measure between 10 and 10.5 meters in length in overhead imagery, depending on the resolution. S-75 sites tend to have a diameter of approximately 0.2 kilometers, although diameters of 0.16 and 0.23 kilometers have also been noted. Deployment in crowded urban areas or in some terrain can necessitate a closer or wider spacing of the site components. The V-750 launch rails are housed in circular revetments between 20 and 25 meters across, with HQ-2 sites having revetments up to 30 meters across.

The following image depicts a typical S-75 site in Yemen. Major components are labeled, including a TET used to transport missile reloads from the storage area to the launch rails.

The common practice of placing the launch rails in sturdy revetments enables inactive S-75 sites to still be identifiable, even though they may have been unused for quite some time.

The following image depicts an inactive, overgrown S-75 site in Germany:


The following images depict the most common S-75/HQ-2 site layouts.

The S-75 site depicted below is a Bulgarian site displaying the classic circular layout:

Some S-75 sites use a compressed layout, positioning the launch revetments far closer to the RSN-75 radar position than is normal. This is commonly seen in Egyptian S-75 sites, such as the one seen below:

Some S-75 or HQ-2 sites use a semi-circle layout, as depicted by the HQ-2 site near Shanghai seen below:

Not all S-75 or HQ-2 sites feature a radar bunker or even revetments. In this case the site must be identified by the number of launchers, the size of the missiles, and any identifiable support equipment. The site depicted below is such an example, found in Libya. Note that sand berms have been constructed around some of the components, but these are a far cry from the sturdy revetments found at prepared site locations.


S-75 and HQ-2 users have developed some unorthodox site layouts for a variety of reasons. Regardless of the layout, two elements will always be present at an S-75 or HQ-2 launch site: the engagement radar, and the missile launch rails themselves. The most common unorthodox site layouts will be discussed here.

Vietnam has created an unorthodox site layout for its S-75 batteries. The revised layout consists of a single RSN-75 engagement radar surrounded by four, rather than six, launch rails, arranged in various patterns. The reasoning behind the revised layout is unclear, but there are a few logical reasons which may be behind the unusual deployment. First, Vietnam may simply be taking launchers and missiles out of service to save maintenance and upkeep costs. Given that the RSN-75 can only prosecute one engagement at a time, reducing the number of launchers at a given site may be strategically acceptable. Secondly, Vietnam may be limiting the number of in-service missiles to reduce the wear and tear on important defensive assets, enabling more missiles to be kept in reserve storage for wartime use. Thirdly, as the revised sites do not maintain the 360-degree layout with respect to the launch rails, reducing the number of rails at certain sites may be indicative of Vietnam's strategic thinking insofar as potential threat ingress routes are concerned. All of Vietnam's S-75 sites feature this layout save one, but even that site is only configured with four launch rails.

The following image depicts a Vietnamese S-75 site near Nha Trang AB using the aforementioned unorthodox equipment configuration:

The Chinese military has been forced to employ an unorthodox HQ-2 site layout due to force modernization issues. A number of HQ-2 sites are apparently being converted to S-300P or HQ-9 sites. In order to mitigate the potential loss of capability while a site is being modernized, the HQ-2 battery is simply relocated off-site to a nearby area.

The following image depicts a Chinese HQ-2 site being modernized to field the S-300P or HQ-9 strategic SAM system. Note the HQ-2 battery which has been repositioned to the northwest of the site being refurbished. In this case, the battery is kept at half-strength.

Once site modernization is complete, some Chinese S-300P or HQ-9 sites appear to retain the HQ-2 battery, which has been relocated back onto the "new" site. This ensures that local air defenses will not be degraded while S-300P or HQ-9 components are procured or produced in sufficient numbers to take up residence at the relevant site or sites.

The following image depicts a recently modernized SAM site configured for the S-300P or HQ-9 system, clearly illustrating the presence of an HQ-2 battery:


While the S-75 does not possess the sheer range of more modern strategic SAM systems such as the S-200 or the S-300P series, it is still capable of fulfilling a prominent role in the air defense network of a given nation.

The following image depicts the coverage provided by identified active S-75 sites in Syria:


The nations listed below have been identified through analysis of Google Earth imagery as being current users of the S-75 or HQ-2 SAM system. The number in parentheses following the nation's name is the number of occupied sites currently visible in Google Earth, followed by the number of currently unoccupied sites in that nation.

Albania (2/0), Angola (2/1), Azerbaijan (1/1), Bulgaria (3/0), China (35/7, HQ-2), Cuba (2/0), Egypt (37/100), Ethiopia (6/1), Iran (3/9, HQ-2), Kazakhstan (3/6), Kyrgyzstan (3/0), Libya (8/4), North Korea (15/5), Pakistan (1/0, HQ-2), Syria (24/18), Turkmenistan (2/15), Uzbekistan (1/0), Vietnam (9/1), Yemen (11/1)


The nations listed below have been identified through analysis of Google Earth imagery as having been former users of the S-75 or HQ-2 SAM system. The number in parentheses following the nation's name is the number of unoccupied sites currently visible in Google Earth, not including those currently occupied by other SAM systems.

Belarus (1), Czech Republic (1), Estonia (1), Germany (6), Hungary (4), India (2), Iraq (17), Latvia (1), Lithuania (2), Mozambique (1), Poland (9), Romania (3), Russia (9), Slovakia (2), Somalia (2), Ukraine (6)


-Jane's Land Based Air Defense 2002-03
-All satellite imagery provided courtesy of Google Earth

-Site measurements were acquired using Google Earth and as such may not be 100% accurate
-For more information on Pakistan's air defense situation, reference the following article at this site: Modernizing Pakistani Air Defenses


Anonymous said...

The first image in the "EXAMPLES OF COMMON SITE CONFIGURATIONS" section is showing a Bulgarian site near Varna, not a Romanian one as written in the text

Sean O'Connor said...

Error corrected, thanks for the catch.

87th_Striker said...

How long does it take to reload a SA-2 launcher ?

Sean O'Connor said...

Roughly 12 minutes, but that can be shortened or extended to a degree depending on the skill level of the crew.