Week of January 20, 1997
S-32: A New Fighter From SukhoiAnonymous sources at the Sukhoi design bureau confirm the information that the company is working on a fifth generation fighter with a forward-swept wing and that its first prototype might be rolled out later this year. Details on the project remain scarce because Sukhoi officials refuse to give any details on this top-secret design. At Farnborough'96 Mikhail Simonov, general designer at Sukhoi, thus answered the question about what a Russian reply should be on the JSF program: "The question is good - we must do something in reply to the JSF or JAST, as it is also called. We will look carefully at how the project develops and think how we should react." He added that the new fighter designs were under study at Sukhoi, but refused to specify them. In its issue 3-4, 1996, the Russian publication "Vestnik Vozdushnogo Flota" (Air Fleet Herald) printed a photo of participants in the Russian Air Force Military Council held in February 1996. Piotr Deinekin, the Russian Air Force commander, and Mikhail Simonov were shown in the picture siting at a desk with two scale models on it. One of those is the Su-37, the other is a totally new design, which is understood to carry designation "S-32". Since the picture was the only one available on the S-32, it has been magnified and re-printed in Western publications. Although the photo is very small, it gives an idea of what the S-32 is. The aircraft obviously has a forward-swept wing (FSW), canards, horizontal stabilizers and two inward-canted vertical tails. Aerodynamically, the S-32 resembles the Su-35, both featuring "tandem triplane" layout.
Forward Swept WingsThe Forward Swept Wing design had been first flight-tested in 1945 on two Junkers Ju-286 prototypes, which then were captured by the advancing Red Army troops. In the following years various FSW configurations were tested in the wind-tunnels of TsAGI, the Central Aerohydrodynamics Institute, located at Zhukovsky near Moscow.Wind-testing showed the advantage of the FSW over ordinary backward-swept wings (BSW) at sub-sonic speeds. However, the FSW did not find applications on mass production aircraft - aluminium alloys used in their constructions were unable to withstand the high torque generated on this type of wing.
X-29: Early Interation Of The S-32In 1984, Grumman flew the X-29A supersonic experimental fighter with titanium elements in the wing framework and cover panels made of composites. The aircraft had canards and FSW with extensive extensions in the place of its junction with the fuselage. Using titanium and composites countered the most unpleasant features of the FSW, mainly aero-elastic instability and low divergention speed. The X-29A flew and thereby proved that supersonic aircraft may have FSW made of composites whose directional pattern of filament is arranged with the wing torque vector.In a wake of the X-29A flights, TsAGI re-started experiments with FSW designs in wind-tunnels. It should be noted that during the Cold War both the USA and USSR practiced wind-testing of scaled-down models of each other's combat aircraft. As a rule, upon completion of the tests, the original models were changed somewhat and placed back in the tunnels for scientific purposes. That is why the pictures of so-called "early-iteration S-32" are, figuratively speaking, a reflection of the X-29A development in Russia. The tests in TsAGI confirmed that the X-29A had better a lift-to-drag ratio at subsonic speeds than aircraft of normal aerodynamic layout, and better characteristics at high angles of attack. In close-in combat the aircraft was found able to out-maneuver existing fighters. However, in the Eighties it was not enough. The focus of military strategists' attention was then put on supersonic speeds, where the X-29A did not do well.
MFI: A Truly Supersonic FighterIn the Eighties the world was re-arming with F-15, F-16, Mirage-2000, MiG-29 and Su-27 agile fighters able to maneuver at high G with the limits being those of the human body rather than the structural strength of airframes. At the same time, those aircraft were not truly supersonic - to maintain supersonic speed they had to use afterburners, which considerably reduced their combat radius and shortened the lives of their engines.At this time the concept of a truly-supersonic stealth aircraft appeared, whose task was to be an effective means against the agile 9-G fighters. Fitted with a powerful radar and armed with fire-and-forget missiles, this aircraft would be able to detect a target at a long distance, launch missiles, turn away and escape from hostile fighters at supersonic speeds. The new concept was embodied in the Lockheed Martin F-22 and its Russian counterpart, the Mikoyan 1-42. The new MiG, also known as the MFI (for Multi-functional fighter), has two Lulka-Saturn Al-41F engines enabling it to maintain supersonic cruise speed without afterburning. Anatoly Belosvet, head of MAPO MiG design office, says the engines move in both pitch and yaw planes. The thrust vectoring system allow control of the aircraft at very low speeds, he adds. According to Belosvet, the MFI development prototype, called 1-44, made its first runs on the runway in 1994, but has not flown yet. The first flight has been repeatedly postponed due to difficulties with canards' actuators and the non-readiness of the digital flight control system (DFCS). Belosvet claims that the aircraft will be flown as soon as development and checks of the DFCS are complete and that the first flight may happen this winter. But technical problems are not the only ones preventing the 1-44 from flying. Over the last few years the Russian Air Force has been suffering from under-financing, spending insufficient money on the MFI project. Some circles in the Defense Ministry consider the MFI as not affordable in considering the deep economic crisis in Russia. Instead, they favour the S-32, which is smaller and cheaper than the MFI.
The Saint Place Is Never EmptyUntil recently the concept of the X-29A seemed to have been given up because the FSW is unacceptable for the truly supersonic fighters due to its low lift-to-drag ratio at supersonic speeds. Today, if the MFI dies, the FSW has a chance to come to life again on the wings of the S-32.The first Sukhoi design to employ FSW was the S-86 propeller-driven corporate plane for 8 persons. It was developed in the late 1980s, but was soon cancelled due to the absence of market demand. The S-86 project allowed Sukhoi designers to get acquainted with the strengths and weaknesses of the FSW in the "tandem triplane" layout. The experience seems to be handy now, when the potential of the Su-27 development comes to an end.
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In fact, Mikhail Simonov has pulled out everything of the basic Su-27 tactical fighter - the aircraft has served as a basis for the Su-30 interceptor, Su-33 deck fighter, Su-34 interdiction aircraft, Su-35 air superiority fighter and its Su-37 version with thrust-vectored nozzles. The time has come for the general designer to show the world a new miracle in fighter design.