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Monday, November 14, 2016

Threat Analysis: Su-35S Part II - Armament R-27 & R-73

Threat Analysis: Su-35S Part I

Image 1: The Su-35 can accommodate a maximum of 17,637 pounds (8,000 kg) of ordinance mounted on 12 external hardpoints. The Su-35 will be armed with three principal air-to-air missiles (AAMs): the R-27, R-73, and R-77. Note: various Russian sources claim the long-range R-37 will be integrated with the Su-35, but no live fire tests of the R-37 from the Su-35 have been documented at this time. Image Credit: Sukhoi.

R-27/AA-10 Alamo

Image 2: R-27 variants. Image Credit: Artem Company.

The R-27 is a highly modular beyond visual range (BVR) missile family designed by Vympel–now the Tactical Missiles Corporation–during the late 1970s for use on the Mig-29 and Su-27 fighters; the missile is currently produced by the Artem Company, a subsidiary to the state-owned Ukrainian export firm Ukroboronprom.[1] The R-27 series of missiles can generally be categorized by their diameter, 230 mm for the baseline variant and 260 mm for the “energeticheskaya” or energetic variants which feature a larger warhead, rocket motor, and extended range.[2] All variants have an 8g maneuverability limit and utilize an active radar proximity fuse to activate the missile’s 73/86 pound (33 kg/39 kg) continuous rod warhead. The R-27 is comparatively larger than most medium range BVR AAMs; the “energetic variants” of the R-27 have launch weights between 343 kg to 350 kg which is more than twice the weight of the 161 kg AIM-120D. The weight, wingspan of the “butterfly” control surfaces, and 4.5+ meter length of the extended range series of R-27 limit external carriage to a maximum of six missiles for the baseline Su-27 Flanker and eight missiles for the Su-35.[3][4] Across both the 230 mm and 260 mm variants, there are four principal guidance types: semi-active radar homing (SARH), infrared (IR), passive radio frequency homing (PRFH), and active radar homing (ARH). Detailed descriptions of each method of guidance are described in the notes section at the end of the article.

The R-27R/RE is the most numerous BVR missile in the VKS inventory and is roughly equivalent to the U.S. AIM-7 Sparrow.[5] The R-27R/RE utilizes an inertial midcourse guidance with radio command updates and a terminal SARH seeker to locate targets. The N135 Irbis is able to illuminate up to two separate targets simultaneously to guide SARH missiles.[6]
The baseline R-27R variant has a range of 38 nautical miles (70 km) against approaching non-maneuvering targets compared to the R-27RE’s 70 nautical miles (130 km) range.[7] The only confirmed instance in which the R-27R was used in combat was the Ethiopian-Eritrean War in 1998-2000 which will be discussed after the R-73.

The R-27T/ET series is visually distinct from all other R-27 variants as a result of its IR seeker in the nose section of the missile. While the R-27T/ET is technically a BVR missile from a maximum kinematic range perspective, in practical terms it is limited to within visual range (WVR) engagements. The missile’s 36T seeker must be locked-on to a target before launch as the R-27T/ET does not feature inertial guidance and cannot receive radio command midcourse updates.[8] The R-27ET features an upgraded seeker which provides greater IR countermeasure discrimination performance and has a maximum acquisition range of approximately eight nautical miles or 15 km.[9]

The R-27P/EP is among the few PRFH AAMs in service. The missile utilizes a passive X-band PRGS-27 (9B-1032) seeker to detect emitting targets from distances up to 108 nm (200 km) away. However, the missile is still constrained by its limited power supply and propellant. Thus, the effective maximum kinematic range against approaching targets is 60 nautical miles or 110 km.[10] Vympel has marketed the R-27P/EP as capable of engaging airborne early warning and control (AWACS) aircraft, stand-off jammers, and fighter aircraft. The R-27P/EP is theoretically able to provide BVR capabilities without alerting adversary radar waring receivers (RWR). However, the missile is constrained in that it requires a cooperative constantly emitting target. The first live fire tests of the R-27P occurred in 1984 and the R-27P entered Soviet Air Force service in 1987. A limited number of missiles were produced prior to the collapse of the Soviet Union by the Artem plant in Ukraine.

R-27A/AE is an ARH variant of the R-27 family which did not enter production as a result of the development of the more advanced R-77.

R-73/AA-11 Archer

Image 3: R-60 (left most) and R-73 missiles on display at the National Air and Space Intelligence Center, Wright-Patterson Air Force Base, Ohio. Through the “Foreign Materiel Acquisition and Exploitation Program”, the U.S. Government has acquired everything from Russian MANPADS to complete S-300V and S-300PMU systems. Image Credit: USAF.

The primary IR guided missile of the VKS is the R-73 which is fulfills a similar role to the American AIM-9 Sidewinder. The R-73 is slightly larger than the AIM-9X, the R-73M2 has a diameter of 170 mm, a launch weight of 110 kg, a 8 kg warhead, and a length of 2.9 meters. Like the Sidewinder, the R-73 family of missiles contains more than half a dozen variants which vary in terms of seeker type, fuse, off-boresight capability, and rocket motor. The Molniya OKB (design bureau) began work on the R-73 during the 1970s in Ukraine with the intent of developing a more maneuverable successor to the R-60/AA-8 Aphid. Responsibility for designing the new missile was transferred to Vympel in 1979 and the R-73 was first operationally deployed in 1984.[11] The R-73’s capabilities were greatly enhanced as a result of the Shchel-3UM helmet mounted sight which enabled off-boresight shots. U.S. pilots were able to thoroughly examine the capabilities of the R-73 and Shchel-3UM through a series of exchanges with the German Air Force in the 1990s. Lt. Col. Fred "Spanky" Clifton (Ret.), an F-16 pilot who was able to fly the Mig-29 in Germany, explains the Archer and HMS was much more effective than expected:

The Archer and the helmet-mounted sight (HMS) brought a real big stick to the playground. First, the HMS was really easy to use. Every pilot was issued his own HMS…Being on the shooting end of the equation, I saw shot opportunities I would've never dreamed of with the AIM-9L/M...In the WVR (within visual range) arena, a skilled MiG-29 pilot can give and Eagle or Viper driver all he/she wants.[12]

Despite the effectiveness of the R-73 and HMS, U.S. pilots generally judged the R-27 was significantly inferior to the AIM-7 and AIM-120. This conclusion was largely made evident a few years later in the Eritrean-Ethiopian War between 1998 and 2000 described later in the article.

The next major evolution in the R-73’s design is the R-74M which features an improved range of 21.5 nm or 40 km, 60°+ off-boresight capability as well as improved dual-band Impuls IR seeker with extended detection range and countermeasure discrimination capabilities. There are two variants of the R-74M, the R-74ML laser proximity fuse variant and the R-74MK with an active radar fuse.[13] The R-74M entered service in 2012, but the Impuls seeker is manufactured by the Arsenal company in Ukraine meaning Russia’s continued access to new R-74M seekers remains in doubt post-Crimea. Russia has had to launch numerous domestic industry programs to mitigate the loss of Ukrainian defense imports.

Image 4: Russia recently undertook a domestic development program to replace the Ukrainian produced Sura-M helmet mounted display for the Mig-29SMT, Su-30SM, and Su-35S.[14]

The latest variant of the R-73 is the R-74M2 which is analogous to the AIM-9X Block II. The R-74M2 features a Karfagen-760 IR seeker, more accurate internal guidance, datalink, and an improved rocket motor.[15]

Combat Record R-27 & R-73

In 1998, the Eritrean Air Force (ERAF) was supplied with an initial batch of six Mig-29s and at least 36 R-27 and 72 R-73 missiles; Eritrean pilots were trained by Ukrainian mercenaries.[16] The Ethiopian Air Force (EtAF) received at least eight Su-27S aircraft, including two Su-27UBK trainers, as well as 80 R-27 and 96 R-73 missiles from Russia between 1998 and 1999. In contrast with the ERAF, the EtAF Su-27s were often flown by Russian pilots.[17][18] Detailed accounts of aerial engagements during the Eritrean-Ethiopian War are sparse. Tom Cooper and Jonathan Kyzer’s article, “Ethiopian Eritrean War, 1998 – 2000”, originally printed in AFM Magazine’s August 2000 edition, is one of the few works to provide detained information regarding the combat performance of the R-27; an expanded version of the article is available courtesy of the Air Combat Information Group. Cooper and Kyzer describe two major engagements during the Eritrean-Ethiopian War in February 1999 and in May 2000 which feature the use of the R-27 and R-73.

February 1999 Engagement:

…on the morning of 25 February four MiG-29s were sent to intercept two Su-27s which were patrolling along the front-lines at Badme. Both Sukhois, flown by Ethiopian pilots, detected the appearance of their opponents in time and attempted to disengage, when - all of a sudden - they came under an attack by several R-27/AA-10 missiles. None of the weapons fired by the Eritreans – which were meanwhile inside the Ethiopian airspace – hit, but after evading them, the Ethiopians decided to turn back and fight. The lead, Maj. Workneh, acquired the enemy and fired what was reported as a "salvo" of R-27s, targeting one MiG-29 after the other. However, all the missiles missed and the only result was that the Eritreans were forced to break their attack - only to be pounced by the faster Su-27s. The result of following dog-fight was one Eritrean MiG-29 shot down, probably by an R-73/AA-11 IR-homing, short range air-to-air missile (fired again by Maj. Workneh).[19] [emphasis added]

Image 5: Russian Su-27 intercepted by the RAAF, this aircraft is armed with a typical mix of R-73, R-27T, and R-73ER missiles. Image credit: RAF. 

May 2000 Engagement:

On 16 May 2000 Eritrean Air Force flew couple of counterattacks against the Ethiopian “left hook”, advancing against the western flank of Eritrean least one MiG-29 was damaged sufficiently to crash-landed at Asmara, obviously after being damaged by R-27. The ERAF remained stubborn: only two days later, two MiG-29s were scrambled to intercept an incoming formation of EtAF MiG-21s. The leading Eritrean pilot missed with his R-27s, but then shot down at least one of Ethiopian fighters, using the 30mm gun during a short dogfight. Nevertheless, only minutes later, the same MiG-29 was in turn intercepted by a pair of EtAF Su-27s. As the Sukhois engaged, one of them collided with an Africa Buzzard (a very large bird), and had to return to base after sustaining heavy damage. The other Sukhoi – flown by one of former Derg-pilots – continued, engaging the MiG and shooting it down by a single R-73.[20] [emphasis added]

Cooper and Kyzer conclude the R-27 likely had a probability kill (PK) less than that of the AIM-7E and AIM-7F Sparrow variants utilized in Vietnam which had a PK of between 8-10%.[21] A maximum of 24 R-27 missiles were fired throughout the war–which were likely the R-27R variant, but only one R-27 managed to maneuver close enough to its intended target such that its radar proximity fuse to activated. In contrast, the R-73 proved itself as a lethal WVR missile; a total of nine missiles were launched resulting in five aerial victories or a PK of 55%.[22] As Cooper and Kyzer explain, the majority of engagements between EtAF Su-27s and ERAF Mig-29s occurred within visual range. Curiously, the Mig-29 – which is often regarded as having superb maneuverability characteristics – performed poorly against the larger Su-27. It’s possible the disparity in aerial victories between the ERAF and EtAF is attributable more towards training and personnel quality issues rather than hardware. It is unclear to the extent, if at all, the engagements between the ERAF and EtAF influenced Russian defense developments in the late 1990s to early 2000s.  

After the poor performance of the AIM-7 in Vietnam, the U.S. made significant investments in upgrading the AIM-7 between 1970 into the 1980s such as greater jam resistance, look-down shoot-down capability, improved rocket motor, etc.[23] However, it is generally understood that the Russian defense industry received little in terms of research and development funding during the 1990s and early 2000s as a result of Russia’s financial difficulties; many new projects had to be sustained by export orders. Therefore, it is unclear to the extent in which Vympel tried to rectify the R-27’s shortcomings through upgrades or design changes to new missile orders. It is also unclear if the engagements during the Eritrean-Ethiopian War had impact on Russian conceptions of ideal fighter characteristics, e.g. such as emphasis on WVR maneuvering. The combination of continued investments in the R-73 while the development of the R-27’s successor, the R-77, lagged suggests the Russian Air Force weighed WVR capabilities as a higher priority.  


AAM Guidance Notes

  • SARH guidance is the process in which the launch platform illuminates a target with its radar and the missile’s onboard receiver detects the reflected radar energy. By comparing the reflected beam’s characteristics to its source, the missile is able to determine the targets position and speed.[24] In order to properly function, SARH guidance requires the launch platform’s radar to continuously track and illuminate the target–which imposes limitations on the launch platform’s freedom to maneuver–and missile’s receiver must continuously detect the reflected radar energy. Furthermore, SARH requires the launch platform’s radar to continuously emit signals thereby exposing the launch platform to radar warning receivers (RWR) and other emission location systems.[25] However, SARH provides substantial BVR capabilities when compared to IR guided missiles.
  • IR guided missiles do not emit signals, rather they home in on heat sources (infrared radiation) such as jet engines. In order to successfully intercept the target, IR seekers must discriminate against background IR radiation sources and IR countermeasures. The first IR guided missiles could only be fired against tail-aspect targets as a result of seeker limitations. Subsequent generations of IR guided missiles such as the AIM-9L are all-aspect capable. The principal limitation of IR guided missiles is the limited detection range of their seekers. The latest generation of IR guided missiles such as the AIM-9X Block II feature lock-on after launch (LOAL) capability. 
  • PRFH missiles similarly do not emit signals, but home in on RF emitting targets.
  • ARH missiles have their own radar seekers which activate during the terminal stage of flight. ARH guided missiles enable “fire and forget” capability i.e. the pilot has freedom to maneuver after initially designated the target with the plane’s radar. By having its own seeker (often a monopulse X-band seeker), ARH missiles are inherently less susceptible to certain forms of jamming.

Author’s Note: I’m still planning on writing that article with 12 Raptors vs 48 Su-35s. There are far more variables than I had anticipated so I’m still researching a couple of topics like Russian air defense doctrines, electronic warfare, “jointness” between the various armed services, battle management networks, datalinks (which are very hard to research) as well as basic fighter maneuvering tactics. As such I’ll probably write an article or two on the topics above for my own edification. Below is a teaser to show some of the assets which will show up in the backstory and simulation:

Note that the 790th fighter regiments do not operate the Su-35S at this time. Only the 22nd and 23rd fighter regiments operate the Su-35S in large numbers (the 159th just received there first four aircraft in November 2016), but more deliveries will take place between 2016 and 2020. A typical squadron of fighter aircraft in the VKS consists of at least 12 aircraft.

Works Consulted

George M. Siouris, Missile Guidance and Control Systems, Springer-Verlag New York, 2004. 

Jeffrey T Richelson, The U.S. Intelligence Community, Westview Press, Jul 14, 2015.

Piotr Butowski, “Russian Air Power Almanac 2015”, Air Force Magazine, 2015.

Sebastien Roblin, "Russia's MiG-29 Fulcrum: A Super Fighter or Super Failure?", July 2016. 

Tactical Missile Corporation, “Products”, last accessed November 2016.

[1] Artem Company, “R-27 missiles”, last accessed November 2016.
[2] Vympel offers R-27EP anti-radar air-to-air missile Piotr Butowski
[3] Artem Company, “R-27 missiles”, last accessed November 2016.
[4] Piotr Butowski, “The Flanker Family Part Two: Upgrades, Su-33 and Su-35”, Combat Aircraft September 2016 Issue, pgs. 61-66.
[5] Sukhoi Products: Su-35 multi-role fighter, last access October 2016.
[6] Piotr Butowski, “The Flanker Family Part Two: Upgrades, Su-33 and Su-35”, Combat Aircraft September 2016 Issue, pgs. 61-66.
[7] Global Security, “AA-10 ALAMO R-27”, last updated November 2011.
[8] Jane’s, “Russian Air-Launched Weapons 38”, 2001.
[10] Piotr Butowski, “Vympel offers R-27EP anti-radar air-to-air missile”, 2007.
[12] Tyler Rogoway, “How To Win In A Dogfight: Stories From A Pilot Who Flew F-16s And MiGs”, 2015.
[13] Piotr Butowski, Jane's International Defense Review, August 2014.
[14] BMPD/ CAST, “Helmet-mounted target designation system NSTS-T for Russian fighter jets”, November 2016.
[15] Piotr Butowski, Jane's International Defense Review, August 2014.
[16] Pieter D. Wezeman “United Nations Arms Embargoes Their Impact on Arms Flows and Target Behavior Case study: Eritrea and Ethiopia, 2000–2001.”
[17] Ibid.
[18] Jonathan Kyzer, et al., Air Combat Information Group, “Air War between Ethiopia and Eritrea, 1998-2000”, 2003.
[19] Ibid.  
[20] Ibid.
[21] Ibid.
[23], “AIM-7 Sparrow”, last accessed November 2016.
[24] Robert L. Shaw, Fight Combat Tactics and Maneuvering, pp. 38
[25] Robert L. Shaw, Fight Combat Tactics and Maneuvering, pp. 38