Su-27UB

Su-27UB
Name	Su-27UB
Type	Twin-seat combat trainer and combat-capable derivative
Manufacturer	Sukhoi

Su-27UB The Su-27UB is a two-seat combat-capable trainer derivative of the Sukhoi Su-27 family developed by Soviet Air Forces and produced by Sukhoi Design Bureau and Irkut Corporation for conversion, testing, and training roles. Conceived during the late Cold War to provide dual-control instruction for pilots transitioning to fourth-generation fighters, the type combines the airframe of the Su-27 with a side-by-side cockpit layout adapted from prototype modifications and reserve development programs. The Su-27UB has been used by air arms including the Russian Air Force, the Ukrainian Air Force, and several export customers, seeing service in training, weapons trials, and limited combat-support tasks.

Development and Design

The Su-27UB project originated as part of a Soviet requirement in the 1970s and 1980s for a twin-seat conversion of the single-seat Sukhoi Su-27 to provide in-flight instruction and operational conversion. Design work at the Sukhoi Design Bureau integrated features developed on prototypes such as the T-10 test series and experimental two-seat demonstrators derived from OKB-51 research. The UB (Uchebno-Boyevoy) retained the twin-engine layout using Saturn AL-31F turbofans produced under NPO Lyulka licensing, while adding a second cockpit with dual controls, ejection seats from Zvezda (aircraft manufacturer), and avionics suites adapted from the single-seat fleet and testbed systems from MiG-29 development programs. Airframe changes included a lengthened forward fuselage and revised canopy glazing, while maintaining hardpoints compatible with ordnance from the Soviet Air Defence Forces and export munitions lists.

Variants and Modifications

Several subtypes and conversions emerged from the Su-27UB line, reflecting diverse roles and modernization efforts. Industrially produced trainers and combat-capable UB airframes were modified by Irkut Corporation and later by KnAAPO for updated avionics, radar cross-section reduction trials, and integration of Western navigation aids following post-Soviet export demands. Upgrades often employed systems from the Su-27SM and Su-30 families, as well as test instrumentation for powerplant trials originating from UMPO. Some UB airframes underwent conversion to demonstrate two-seat versions of advanced multirole fighters in export demonstrations for delegations from People's Republic of China, India, and Vietnam.

Operational History

The Su-27UB entered service with the Soviet Air Forces and, after 1991, with successor forces including the Russian Air Force and the Ukrainian Air Force. It was used for pilot conversion, tactical evaluation, and developmental weapons trials supporting programs such as integration of air-to-air missiles from the Vympel NPO lineage and guided munitions from Tactical Missiles Corporation. UB trainers participated in large-scale exercises like Zapad and Vostok series maneuvers and were deployed in peacetime patrols and aerial displays at events such as the MAKS Air Show and national flypasts. During regional conflicts in the post-Soviet space, some UB airframes performed secondary roles including forward air control, reconnaissance with podded sensors, and—on occasion—combat sorties under dual-crew operation. Exported UB variants served in air arms such as the People's Liberation Army Air Force and air forces of several African Union and Association of Southeast Asian Nations member states, underpinning bilateral training programs and joint exercises.

Technical Specifications

The Su-27UB shares baseline structural and propulsion characteristics with the single-seat Su-27 family. Typical technical data include twin AL-31F turbofan engines with afterburning capability, a substantial fuel fraction supporting extended ferry ranges, and a multi-station hardpoint arrangement for air-to-air missiles such as the R-27 and R-73, unguided rockets, and external fuel tanks. Avionics suites vary by modification, with some UB aircraft fitted with upgraded pulse-Doppler radars adapted from the NPK Saturn product line and inertial navigation systems co-developed with Konsortium Oborony specialists. Flight-control harmonization preserves high angles-of-attack handling characteristic of the Su-27 lineage, aided by leading-edge root extensions and twin-tail empennage geometry derived from the original T-10 aerodynamic concept.

Operators and Service Use

State operators historically include the Soviet Air Forces, Russian Air Force, Ukrainian Air Force, and export customers across Asia, Africa, and Eastern Europe. In Russian service UB variants have been assigned to operational conversion units within training centers such as the Kacha Military Aviation School and frontline regiments subordinated to commands like the Long-Range Aviation Command and regional air armies. Ukrainian UB airframes were part of regiments based at bases formerly belonging to the Soviet Air Defense Forces network and later inherited by newly formed air arms. Export deliveries often accompanied bilateral military-technical cooperation agreements and were supported by on-site instructor detachments from Sukhoi.

Survivors and Museums

Several Su-27UB airframes are preserved in static display at aviation museums and exhibition centers. Notable preserved examples appear at institutions such as the Central Air Force Museum in Monino, the Ukrainian State Aviation Museum in Kyiv, and aviation parks in Beijing and Orenburg. Demonstration airframes and prototypes have been exhibited at the MAKS Air Show and in aviation heritage collections maintained by former test centers such as Gromov Flight Research Institute.

Category:Sukhoi aircraft Category:1980s Soviet aircraft