"Sukhoi is to offer South Korea an enhanced version of the Su-35 fighter, equipped with the NIIP NO-11M phased-array radar 1553 digital databus and a cockpit featuring multifunction colour displays and a sidestick control column, following recent test flights of a new Su-37 multirole demonstrator - the T10M-12.
Sukhoi has offered South Korea a licence for partial assembly of the Su-35 from Russian components, 100% local servicing and technology transfer, according to Russian media sources. The Sukhoi proposal also includes offsetting the cost of the aircraft against Russia's large debt to South Korea.
The economic downturn in Asia has caused a slowdown in South Korea's F-X fighter programme. A request for proposals was expected in July, but the programme is unlikely to get under way before 2000 (Flight International, 26 August-1 September).
The test aircraft, number 712, will soon be fitted with Lyulka Saturn AL-31FP thrust vectoring engines, which are now under test on two Su-30MK fighters.
The Tl0M-12 has so far not been shown publicly and is under- going trials alongside the two Su-30MKs with AL-31FP engines. Increased thrust AL-3 1FMs are reported to be under development.
Flight tests of the AL-31FPs began on the second prototype Su- 30MK on 23 March, according to Su-27M programme manager Vladimir Konokhov. The nozzles are vectorable as in previous AL-31 derivatives, but move in the horizontal, not vertical, plane. The engines are mounted at a 32deg off-vertical angle, so that the nozzles can move in intersecting planes, giving an X-shaped vectoring path when viewed from astern. The nozzles are driven by the aircraft's flight control system, giving enhanced manoeuvrability in combat.
Increased use of titanium has reduced the weight of the nozzle significantly, as well as doubling the service life from 2 50h to 500h.
The Ufa Motor Building plant has begun producing 88 AL-31FP engines for India's 40 Su-30MKI multirole fighter. The Su-30MKs already delivered to India are equipped with earlier non-thrust vectoring engines, which will be replaced by the Al-31EP The final prototype Su-37, with a complete fire-control system and avionics of all-Russian manufacture, together with AL-31EP engines, is to be shown at the Paris airshow in 1999, according to Konokhov."
(from Flight International, 9-15 Sept., 1998, p. 32)
To clarify the information above, the nozzles of Su-37 are capable of 19deg movement in two opposite directions. Originally, the nozzles were installed for vertical movement and both nozzles operated in the same plane. This is called 2D thrust vectoring. Providing the aircraft with 3D vectoring (when the nozzles can direct thrust in different planes) was the goal of the new AL-31FP engine configuration. First, the nozzles were rotated by 90deg to operate in the horizontal plane. But the tail sting (which houses the rearward-facing radar, brake parachute, flare and chaff dispensers, aft oblique RHAW antennas, spine integral fuel tank, tail radome) was obviously in the way of the nozzles and the jet stream (see photos to the left - the tail sting is considerably longer than the nozzles). So, the entire engine assemblies were rotated further 32deg in opposite directions (possibly towards each other) to give room to the nozzles. This resulted in two separate TV planes intersecting at 84deg (possibly below the aircraft). This in fact is a differential 3D thrust-vectoring achieved with nozzles each capable of movement in 2D only. And, most importantly, the tail sting remained. Quite ingenious.
Venik
