R-40 (missile)

R-40 (missile). The R-40 (NATO reporting name: AA-6 "Acrid") is a long-range, Cold War-era air-to-air missile developed by the Soviet Union for its premier high-altitude interceptor aircraft. Primarily deployed on the Mikoyan-Gurevich MiG-25 "Foxbat" and later the Mikoyan MiG-31 "Foxhound", it was designed to engage large, high-flying targets like the Boeing B-52 Stratofortress and Lockheed SR-71 Blackbird. As one of the largest and heaviest air-to-air missiles ever fielded, the R-40 represented a significant capability for the Soviet Air Defence Forces (PVO) during a period of intense arms race competition with the United States.

Development and design

The development of the R-40 was initiated by the design bureau MKB Vympel in the early 1960s, specifically to arm the new Mikoyan-Gurevich MiG-25 being created to counter perceived Western strategic threats. The missile's substantial size was dictated by the need for a large warhead and a powerful rocket motor to achieve the necessary range and speed to intercept targets like the XB-70 Valkyrie. The design incorporated two primary seeker variants to ensure engagement flexibility: the radar-guided R-40R (R for "radiolokatsionnaya") and the heat-seeking R-40T (T for "teplovaya"). This dual-seeker approach, a hallmark of Soviet missile design, allowed pilots to engage targets using either the aircraft's powerful RP-25 Smerch radar or passive infrared detection, complicating enemy electronic countermeasures and evasion tactics. The missile's aerodynamics and control surfaces were optimized for stable flight at the extreme altitudes and speeds characteristic of the Mikoyan-Gurevich MiG-25's mission profile.

Operational history

Entering service with the Soviet Air Defence Forces around 1970, the R-40 became a key component of the Mikoyan-Gurevich MiG-25's armament, symbolizing the reach of Soviet air defense networks. The missile was exported to several allied nations, including Syria, Libya, Algeria, and India, where it saw limited operational use. During the Iran–Iraq War, Iraqi Air Force Mikoyan-Gurevich MiG-25s reportedly fired R-40 missiles against Islamic Republic of Iran Air Force aircraft, though with disputed success. The missile's limitations, including its size, weight, and relatively primitive guidance compared to contemporary Western missiles like the AIM-54 Phoenix, became apparent over time. It remained in limited service on upgraded Mikoyan MiG-31 interceptors in Russia and other former Soviet states into the early 21st century, before being superseded by more advanced missiles like the R-33 (missile).

Variants

* R-40R (AA-6A "Acrid"): The baseline model featuring semi-active radar homing (SARH) guidance, dependent on illumination from the launching aircraft's radar such as the RP-25 Smerch radar. * R-40T (AA-6B "Acrid"): An infrared homing variant designed for passive engagements, particularly against targets with strong heat signatures like the Pratt & Whitney J58 engines of the Lockheed SR-71 Blackbird. * R-40RD / R-40TD: Improved late-Cold War models with enhanced seekers, improved propellant, and better resistance to countermeasures. The "D" suffix denoted "Dalnovoboynaya" (long-range). These versions offered increased range and more reliable performance.

Specifications

* **Length:** 6.22 m (R-40TD); 5.98 m (R-40RD) * **Diameter:** 0.31 m * **Wingspan:** 1.45 m * **Launch Weight:** 470 kg (R-40TD); 461 kg (R-40RD) * **Warhead:** Large high-explosive fragmentation * **Propulsion:** Single-stage solid-fuel rocket motor * **Speed:** Mach 4.5 * **Range:** Up to 30 km (R-40R/RD); Up to 50 km (R-40T/TD) * **Guidance:** Semi-active radar homing (R-40R/RD) / Infrared homing (R-40T/TD) * **Launch Platform:** Primarily the Mikoyan-Gurevich MiG-25 and Mikoyan MiG-31.

Operators

* Current: ** Algeria – With remaining Mikoyan-Gurevich MiG-25 fleet. ** Syria – With Syrian Air Force Mikoyan-Gurevich MiG-25s. * Former: ** Soviet Union – Passed to successor states. ** Russia – Retired from service. ** India – Used on Indian Air Force Mikoyan-Gurevich MiG-25s. ** Libya – Used by the Libyan Air Force under Muammar Gaddafi. ** Iraq – Used by the Iraqi Air Force during the Iran–Iraq War and Gulf War. ** Bulgaria ** Kazakhstan

Category:Air-to-air missiles of the Soviet Union Category:Cold War air-to-air missiles of the Soviet Union