OVERVIEW:The Sukhoi Su-25 Grach (NATO reporting name: Frogfoot) is a single-seat, twin-engine jet aircraft developed in the Soviet Union by Sukhoi. It was designed to provide close air support for the Soviet Ground Forces.

DETAILS:The Su-25SM (Stroyevoy Modernizirovannyi) is an "affordable" upgrade programme for the Su-25, conceived by the Russian Air Force in 2000. The programme stems from the attempted Su-25T and Su-25TM upgrades, which were evaluated and labeled as over-sophisticated and expensive. The SM upgrade incorporates avionics enhancements and airframe refurbishment to extend the Frogfoot's service life by up to 500 flight hours or 5 years.

The Su-25SM's all-new PRnK-25SM "Bars" navigation/attack suite is built around the BTsVM-90 digital computer system, originally planned for the Su-25TM upgrade programme. Navigation and attack precision provided by the new suite is three times better of the baseline Su-25 and is reported to be within 15 m (49 ft) using satellite correction and 200 m (660 ft) without it.

A new KA1-1-01 Head-Up Display (HUD) was added providing, among other things, double the field of view of the original ASP-17BTs-8 electro-optical sight. Other systems and components incorporated during the upgrade include a Multi-Function Display (MFD), RSBN-85 Short Range Aid to Navigation (SHORAN), ARK-35-1 Automatic Direction Finder (ADF), A-737-01 GPS/GLONASS Receiver, Karat-B-25 Flight Data Recorder (FDR), Berkut-1 Video Recording System (VRS), Banker-2 UHF/VHF communication radio, SO-96 Transponder and a L150 "Pastel" Radar Warning Receiver (RWR).

The R-95Sh engines have been overhauled and modified with an anti-surge system installed. The system is designed to improve the resistance of the engine to ingested powders and gases during gun and rocket salvo firing.

The combination of reconditioned and new equipment, with increased automation and self-test capability has allowed for a reduction of pre- and post-flight maintenance by some 25 to 30%. Overall weight savings are around 300 kg (660 lb).

Su-25SM weapon suite has been expanded with the addition of the Vympel R-73 highly agile air-to-air missile (albeit without helmet mounted cuing and only the traditional longitudinal seeker mode) and the S-13T 130 mm rockets (carried in five-round B-13 pods) with blast-fragmentation and armour-piercing warheads. Further, the Kh-25ML and Kh-29L Weapon Employment Profiles have been significantly improved, permitting some complex missile launch scenarios to be executed, such as: firing two consecutive missiles on two different targets in a single attack pass. The GSh-30-2 cannon (250-round magazine) has received three new reduced rate-of-fire modes: 750, 375 and 188 Rounds per Minute. The Su-25SM was also given new BD3-25 under-wing pylons.

SOURCE: [SCO] Wikipedia http://en.wikipedia.org
