In the Works: Sukhoi S-21
Sukhoi is continuing its feasibility studies on the S-21, a supersonic business jet, but officials do not give consistent answers to the question of when the aircraft will appear. “At very best,” said Andrei Ilyin, general director of Sukhoi Civil Aircraft, “an SSBJ would not appear before 2010 or 2012.”
But Victor Soubbotin, the firm’s technical director, told AIN, “It will take 10 years or so [from now] for optimization of the sonic boom.” And this is just to optimize the sonic boom. Presumably, there would be more work after that, making even 2014 too optimistic.
This inconsistency notwithstanding, Sukhoi is intent on penetrating the business jet market, but will not launch any such project until it completes engineering of the Russian Regional Jet. Ilyin said the company would not attempt “a conventional business jet because there are too many famous makers present with such designs already. We do not have a chance with an aerodynamically conventional design, but we can get our place with an advanced, high-performance aircraft.” He characterized Sukhoi’s current efforts with the program as being “more in the research and technology field.”
The S-21 project began in 1989, and in the mid-1990s engineers conducted intensive wind-tunnel testing on various models. In the past two years the focus shifted to work on technologies and understanding the nature of sonic booms. Ilyin said that “considerable achievements” have been made, which together with other achievements over the past 15 years of sustained research make Sukhoi “a leader in SSBJ technologies.”
The current S-21 design calls for two engines instead of three, which were deemed to be too expensive. Research also showed the central, above-the-fuselage engine nacelle created undesirable aerodynamic complications. Officials are reconsidering the earlier selection of the AMNTK Soyuz VK21 engine, although work to improve this engine continues. An all-new engine would likely have to be the product of an international cooperative effort.