Su-33 Navy Flanker Su-33 - naval version of Su-27 (formerly designated as Su-27K "Korabelnij" or "Shipborn")- derivative of the Su-27, with canards added, folding outer wing panels, strengthened undercarriage with twin nosewheels, arrester hook. The use of thrust-vectoring nozzles on the production aircraft is considered. Basically a navalised su-27 with limited multi-role capability, the Su-33, originally evolved as the Su-27K, is the first production version of the Sukhoi fighter to adopt the so-called "unstable integrated three-plane" configuration. Having the movable foreplane first evaluated by prototype T-10-24, the initial prototype of the Su-33 shipboard fighter was flown as the Su-27K-1 (T-10-37) on 17 August 1987. This had a strengthened undercarriage embodying a twin-wheel nose member and an arrester hook. The second prototype Su-27K-2 (T-10-39), added to these new features folding outer wings and tailplane panels. The two aircraft initiated deck trials aboard the carrier Kuznetsov on 1 November 1989. Subsequent prototypes standardised on the features of the Su-27K-2 and introduced a flight refuelling probe, reduced-length tailcone and provision on the centreline for 330 Imp gal (1,500 l) drop tank or a 9,920 lb (4,500 kg) H-41 Moskito long-range anti-shipping missile. It was originally proposed that the series Su-33 would be equipped with thrust vectoring nozzles for the AL-31F engines. There is now some doubt, however, that these will be adopted by the shipboard fighter owing to economy measures and strictly limited production foreseen since abandonment of the former Soviet Union's plan to field four 60,000 ton conventional carriers, only one, the Kuznetsov, now being expected to serve with the Russian Navy. The Su-33 is to carry the moskito AShM in concert with under wing H-31 missiles for the attach mission and similar armament to that of the Su-27 in the air-to-air role. Apart from modest increases in weights, the specification of the Su-33 is essentially similar to that of the Su-27. The visual differences from basic Su-27: IR sight moved to right side of canopy(1) Refueling system is installed(2) Canard foreplanes(3) Two-weel nose gear(4) Arrester hook(5) Folding outer wing panels(6) Reduced-length tailcone(7) Centreline dock for large drop tank or heavy anti-ship missile(8)