SUKHOI PLANS to complete development tests in 1997 of the Su-25TM all-weather version of its Frogfoot attack aircraft, says Vladimir Babak, chief designer for the programme. A new designation, Su-39, has been adopted for the modernised aircraft by the design bureau, although it is not yet approved by the air force.
The Su-39 will be equipped with Phazotron Kopyo-25 multi-function radar pod-mounted on the centreline station under the fuselage. The Kopyo-25 is a derivative of the radar offered for modernisation of the Mikoyan MiG-21, with full air-to-air and air-to-ground capability, including ground mapping in Doppler-beam sharpening and synthetic-aperture modes. According to Babak, the first container pod is being outfitted with radar components at Phazotron and will be ready for the flight tests in May. The radar has a flat-slotted antenna, 500mm in diameter, scanning ±40¡s in azimuth and +20/-40¡ in elevation. A detection range is claimed for the radar of 25km (14nm) for a group of tanks and 22km for a small naval vessel.
In the air-to-air mode, detection of a fighter-class target is provided at 16km in head-on situations, or 7km in tail-on situations.
Babak says that the contract for the modernisation programme was issued by the air force, and sufficient funding is being provided for the Su-25 upgrade development effort. So far, one Su-39 has been completed by the Ulan-Ude production plant. Two Su-25Ts of a pre-production series of eight aircraft manufactured at Tbilisi, in Georgia, have also been converted.
The major weapon of the Su-39 is the Vikhr anti-tank guided missile, 16 of which can be carried under the wing.
Air-to-air weapons options will include the Vympel R-27, R-27ER (AA-10 Alamo), Molniya (AA-8 Aphid), R-60 and Vympel R-73 (AA-8 Aphid), Vympel R-77 (AA-12 Adder) missiles. The Su-39 may carry four Zvezda Kh-31A (AS-17 Krypton) or Zvezda Kh-35U (AS-X-20) anti-ship missiles, as well as four Raduga Kh-58U (AS-11 Kilter) radar-suppression missiles.
The infra-red (IR) signature of the Su-39 has been lowered by a factor of three to four, Sukhoi says, and an IR Sukhogruz jammer has been placed in the bottom of the vertical fin.
Extra air intakes on the upper surface of the engine nacelles convey cooling air into the jet exhaust, while hot turbine blades are hidden from the view of approaching infra-red seekers by a specially shaped centre-body installed in the gas flow after the turbine. The UV-26 dispenser houses 19mm infra-red flares or chaff cartridges.
Source: Flight International