by Roy Cochrun
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"Berkut" Extending Horizons

Three years ago the highly maneuverable aircraft with forward swept wing took off in Russia.

Future Hero of Russia, the test pilot Igor' Votintsev, lifted it off on 25 September 1997.  And in October 2000, the experimental S-37 "Berkut" with its forward-swept wing will take off for the 100th time.  Through today, the Sukhoy OKB has completed a major phase of the tests of the aircraft, which has caused real interest around the world.  Without a doubt, the results received will be used in the designs of fighters of the future.  Of fighters, which...  But first, some history.

So, the "Berkut" took off on 25 September 1997.  And in November, a representative of the congressional tactical aviation subcommittee of the USA's national defense   committee, Kurt Weldon, noted in the New York Times:  In the opinion of defense experts, the development of the S-37 signifies that in the 21st century, American pilots may meet  an even more formidable enemy than had been expected earlier.  Russia is continuing to realize technological developments.  This technological 'leap' may give the Russians a significant potential.  The new airplane will allow them to equal the achievements of the USA in recent years.  The S-37 was built to give the Russians exceptional capabilities for achievement of what is called 'mastery in the air.'" 

We shall note that in the '70s, they began the ATF future fighter program in the USA, which lead to the appearance of the experimental airplanes Lockheed F-22 (afterward the Lockheed-Martin YF-22A "Raptor") and the Northrop YF-23.  In the Soviet Union research was begun on a program for the creation of "a fighter for the '90s," the I-90.  In particular, it was determined that in the general system requirements for the future fighter high maneuverability (the ability to maintain stability and flight control at practically any angle of attack) was one of the priorities.  The high maneuverability figured in the requirements for the ATF fighter also.  However, having come up against hard-to-solve tasks, the Americans sacrificed the maneuverability capabilities somewhat.

Combat experience shows that dogfighting will remain unavoidable.  And even with the introduction of long-range missile combat, specialists think that the advantage will belong to whom, with consistent fire in various sectors, will be able at the moment of launch to get his fighter in the direction of the target for a more complete use of the dynamic capabilities of his own missiles.  Under these conditions maximum high angular turn rates and speed ranges at which weapons may be used have special significance.  Therefore, the hard requirements for the fifth generation fighter's maneuverability remain unchanged.

The Sukhoy OKB, while working on the program of the Su-27 fighter, the most maneuverable in the world, proposed an aircraft with a forward-swept wing with high maneuvering characteristics at subsonic speeds (in particular, the ability to maintain stability and control at critical angles of attack up to 60 and more degrees) and while not conceeding to better fighters as supersonic speeds.  Mikhail Pogosyan - the Chief Designer of the aircraft - was named project manager (since March 1998 it is Sergey Korotkov), and Sukhoy OKB General Designer, Mikhail Simonov, was general manager.  At the end of the '80s, with the utilization of other aircraft production associations work was started on the preparation for construction of the experimental aircraft.

"In the beginning of the '90s, Russian defense expenditures were sharply curtailed, however, the OKB decided to continue the work," says S-37 aircraft chief designer, Sergey Korotkov.  "We have proceeded from the need to maintain advanced aircraft building technology.  After all  it is enough even for one link in the chain of sequential change in the generations of combat aeronautical engineering to drop out, and this absolutely leads to a loss in capabilities to independently develop and produce contemporary fighters.  This is precisely what happened with Germany, Great Britain and Japan, who have been left one generation behind Russia, the USA and France."

In the spring of 1997, the first example of the S-37 "Berkut" was built - a flying test bed.  They "pressed it out" on the bench, while not allowing the work to become a burden.  Then for the first time in the practice of domestic aircraft construction methods were worked out which allow with a rather high precision the determination  of the extreme design structural  characteristics, while not wrecking the aircraft in static testing.  In the summer of that same '97, the "Berkut" "was transferred" to the Mikhail Gromov Flight Test Institute.  In the beginning of September high speed taxi tests were begun, and on the 25th, I will repeat, the aircraft, piloted by test pilot Igor' Votintsev, left on its first flight.  Without a doubt, it became a brilliant occurrence for the Russian aircraft industry.  For all of Russia.  Today the Sukhoy OKB, with the S-37 having flown in the supersonic regimes, has completed a major phase of the flight tests.

They, in the opinion of OKB specialists, have confirmed the the calculated advantages of the forward-swept wing for a maneuvering aircraft.  The received results have exceeded the preliminary estimates of the designers.  The airplane is stable up to very high angles of attack at subsonic speeds and significantly exceeds the well known Su-27 in maneuverability.  As the test pilot, Hero of the Russian Federation, Igor' Votintsev, who is performing the "Berkut" flight tests, has born witness, the aircraft's control at the checked regimes remains light and steady.

The forward-swept wing is the most striking and effective external "Berkut" feature, which sharply distinguishes the appearance of this aircraft from all others.  However, this is by far not its only achievement.  The aircraft's airframe was built with the use principally new solutions.  The use of large-sized panels up to 8 meters long have achieved  extremely high surface smoothness and keep fasteners to a minimum.  This has improved the aerodynamics and lowered the mass.  Other advanced technical solutions and technology also have been realized in the design of the "Berkut.  It was built around principally new fifth generation engines developed by AO Lyul'ka-Saturn (D-30F6 engines are installed on the experimental S-37).  The new avionics suite that will equip the "Berkut" must provide automated control of various systems (including systems with elements of artificial intelligence).

The solution algorithm for development, construction, and tests of the experimental S-37 "Berkut," in the opinion of the Chief Designer, Sergey Korotkov, reflects the strategy selected by the Sukhoy OKB of a staged construction of a new fighter.  A number of technical solutions included in the S-37 project was realized first on other of the firm's aircraft.  The building of the experimental aircraft allowed the concentration of the collective's strengths in more critical areas.  Today the S-37 is an instrument which permits the broadening of the horizons in aircraft construction technology and provides Russia a revolutionary "break-through into a new dimension."  Authoritative foreign aeronautical specialists note that the Russian airplane has reach a qualitatively new level in comparison with all the fighter built  in Russia and earlier in the USSR.  One may look at the "Berkut" as a uniue flying testbed for working out a wide circle of advanced technical solutions, which will be used in the designs of various aircraft of the 21st Century both military as well as civilian designation. 

It follows to speak today about the follow-on, too.  Several days ago, and precisely on 18 September, for the first time the American experimental light multirole JSF fighter lifted off.  Some media already have noted that with the appearance of this fifth generation aircraft "there will be nothing for Russia to do in the sky and on the worldwide aviation arms market soon."  It is thought that this is a premature announcement.
"The American aircraft must still show itself," Sergey Korotkov says.  "The 'Berkut' has completed almost 100 flights already.  We have completed two test programs and are starting a third -- we are extending the hardware restrictions.  The time for construction of a fifth generation fighter in Russia still has not been let go.  The air force must determine its position with the look of a modern aircraft.  We shall make our presence felt."

Let's note that the development of a future tactical fighter - about which the Minister of Defense, Marshal of the Russian Federation, Igor' Sergeev, announced  in the pages of our newspaper - is in the plans of the Russian military leadership.  Moreover, it is one of the basic priority thrusts in the development of weapons systems and military technology for the next decade.  Russia, without a doubt, must have its own fifth generation fighter among the first and not  become like the powers who have "left out the link in the chain," who have left the ranks of right-flank worldwide aircraft construction.  The successfully continuing flight tests of the S-37 are a huge step on the way to the execution of a complex of requirements for a future fighter.  The "Berkut" soaring in the sky with the enchanting shape shows the ability of the Russian aviation industry to develop modern aircraft technology and its readiness to compete in the future with the leading foreign developers.  The Russian air force will have a next century fighter.

Source:  25.09.00, Krasnaya Zvezda, Anatoliy Dokuchaev