35 years ago, on April 13, 1990, the Su-27IB (Su-34) made its first flight.

 #OTD 35 years ago, on April 13, 1990, the Su-27IB (Su-34) made its first flight.

Work on a strike modification of the Su-27, designated Su-27Sh (attack aircraft), began at the Sukhoi Design Bureau in 1979. It was based on studies involving the use of a conformal fuel tank (CFT) mounted between the engine nacelles. The CFT significantly improved the Su-27's range characteristics. Alongside the CFT, a proposal was made to use a conformal weapons container (CWC). In January 1980, this concept was presented to the General Designer, and after his approval, detailed development began. The baseline aircraft considered was the two-seat Su-27UB, but with a modified fire control system (FCS).

 

Enhancing the Su-27Sh's capabilities against ground targets was planned by expanding the range of weapons through the integration of specialized guidance containers ("Ryabina," "Tekon-1M," "Progress-N"). This effectively allowed for an "internal" weapons payload of 8 tons. Work on the strike variant of the Su-27 was reinvigorated in 1983 with directives to prepare two technical proposals for the Su-27M and Su-27IB, based on the modernization of the Su-27UB. This time, the use of CWC and CFT was not considered. 

Later, development shifted to the Su-27UB with the "Voshod" FCS, originally designed for the Su-25TM attack aircraft. In the spring of 1986, at the initiative of General Designer M.P. Simonov, a decision was made to explore a fundamentally new layout with both crew members seated side-by-side. The primary reason for this choice was a proposal to unify the main avionics suite of the Su-27IB with the equipment of the T-60 bomber (Su-24BM2), which was being designed concurrently at the bureau. The goal was to reduce development costs for both aircraft.

 As a result, the Su-27IB was equipped with a phased-array radar optimized for ground target engagements and an integrated laser-television sighting system developed by UOMZ. Additionally, a welded titanium cockpit was introduced. Otherwise, the aircraft was to be maximally unified with the Su-27M. However, due to the forward shift in the center of gravity and changes in load geometry, the entire fuselage had to be redesigned. Only the tail assembly was planned to remain unchanged.

The result was increased drag, years of refinement, and, indeed, a unique "mutant" with no analogs.

 

Btvt.info commentary:

What do we see here? As usual, an adventure by the chief designer and budget siphoning. It all started correctly—an analog to the "Strike Eagle" based on the Su-27UB airframe without major modifications. The initial project with the CWC was even progressive—everything was as it should be: unification, external containers, versatility—essentially a two-seat Su-27M (Su-35). But the chief designer abandoned this successful and logical option to create a "mutant." Why?

 

The chief designer clearly understood that installing a new, heavy nose section would require a complete redesign of the aircraft's airframe, which would take many years and promise substantial funding and numerous patents with financial rewards. By the late 1980s, it was becoming clear that orders would be scarce, so they thought, "Why not milk some money from this pointless project for 10–15 years?" The result: an additional 4 tons of parasitic weight due to all these redesigns and "toilet" overhauls.

They would have continued showcasing their unparalleled "toilet" with a 1.5-ton titanium cockpit at exhibitions if not for the war. The war exposed the failure of this duck's concept—not a bird, but a "duck" in another sense. Ultimately, the Su-34 now performs tasks that, for example, the Su-7B from the 1960s could have handled—dropping glide bombs, the guidance of which is entirely independent of the platform itself.