The Russian aerospace industry is delaying the full-scale launch of a second-generation supersonic transport aircraft (SST2) while stepping up efforts to develop the key technologies needed to achieve this ambition. The change of course was confirmed at a high-level government meeting last month when President Vladimir Putin himself endorsed a proposal from state-backed companies to develop the new Strizh (Swift ) which will be powered by Klimov RD-93MA turbojets (a non-afterburner derivative of the MiG-35 fighter engine).
With a takeoff weight of 16 tons (35,273 pounds), the Strizh would serve as a platform to evaluate a set of new technologies such as pro-bionic airframe structural design (instead of conventional frames and ribs) and technical advances in engine / airframe integration. to reduce the noise footprint around airports.
After completing wind tunnel and hot gas testing on scale models, the industry is now awaiting a government response to its proposal to build the 125-foot-long vehicle capable of accelerating to speeds of up to Mach 1.8. If the Kremlin funding materializes in a timely manner, construction and flight testing would take place between 2022 and 2026.
Heavier and faster than the NASA / Lockheed-Martin X-59 Supersonic Silent Technology Transport (QueSST), the Strizh features a wedge-shaped nozzle and inverted V-wing to reduce bang sonic and noise levels. The characteristics would allow it to sail at Mach 1.7 at an altitude of 51,000 feet while producing a sonic boom quieter than 85 dB. While this does not match the overall performance targeted by some in the aviation industry for a future supersonic business jet, and by extension a supersonic airliner, Russian developers believe the Strizh would be the next step towards a viable supersonic future.
The developers of the US Project X-59 and Strizh intend to conduct flight tests in response to the community to enable the meeting of the ICAO Committee on Aviation Environmental Protection (CAEP13) to establish a sonic boom standard in 2025. Without such a standard and SST2 certification rules covering the tolerance of sonic boom intensity over populated areas and cities, any development of supersonic aircraft could seriously start. trading would probably become too risky.
These considerations seem to have prompted the Russian government to devote more time and money to basic research and technological maturation. In September 2020, the administration approved the formation of a special consortium of national science centers to address the issue.
This led to the launch in December 2020 of the new world-class Sverkhzvuk Science Center (better known as TsNTU Sverkhzvuk or Supersonic Center). Russia’s Ministry of Industry and Trade has committed funding of around $ 34 million through 2025 on condition that six industry partners contribute at least $ 7.6 million from their own resources.
At the MAKS airshow in July 2021 in Moscow, the Russian aerospace industry presented several models of potential supersonic transport designs. (Photo: Vladimir Karnozov)
The TsAGI research institute (the Central Aero Hydra Dynamics Institute named after Zhukovsky) leads the consortium with a staff of 4,600 people working in more than 60 wind tunnels and other test devices. The main objective is to define a set of standards and critical technologies to enable the development of an SST2, as well as the necessary supporting infrastructure, and to give the Russian aviation industry a chance to take the lead in the 21st century supersonic racing.
However, the budget of around $ 41 million allocated so far is only a fraction of the estimated costs to launch SST2. It is estimated that developing a suitable engine will likely cost an additional $ 640 million. The parameters required for the propulsion system include an exhaust gas velocity of less than 1,300 feet per second on take-off and a specific fuel consumption (SFC) of one pound of thrust per pound of fuel used in one flight hour. .
In comparison, the CFM56-7B turbojet engine commonly used on Western narrow-body airliners has an SFC ratio of about half a pound of thrust per pound of fuel used in an hour, but it has a more efficient bypass rate. of 5.1. On this basis, the SFC for the powertrain of the envisaged Russian aircraft SST2 would be a technical achievement at speeds of Mach 2 by 2030.
But the initial funding at least gives Russia’s OSH team a fresh start. Over the next six years, the Supersonic Center was mandated to organize no less than 131 conferences and 43 educational programs, publish 78 Q1 / Q2 level scientific papers in the Scopus / Web of Science Core collection, and train 349 young aerospace scientists. for industry. Plans call for its team of scientists to grow from 39 today to 50 in 2025.
The aircraft’s design goals for the new initiative include an increase in lift-to-drag ratio for possible SST 2 in sustained cruise from 20 to 25 percent, a reduction in fuel consumption by 15 percent and 7-10 dB sonic boom intensity, and ensure at least a 5-7 dB margin with current ICAO Chapter 14 noise limits.
“We’re not just talking about pure science and technology, but the certain level of system integration that is reflected in a proposed aircraft design of a current iteration,” said Cyril Sypalo, head of both TsAGI and the new supersonic center at a conference during the MAKS in July. air show in Moscow. “Shaping the design of airplanes is a very important issue for us. We have already moved from the R0 configuration to the R1 configuration and will continue to refine the aircraft design down to at least R5 as the technologies and methods mature. Our work will not end in 2025 with the presentation of the results to the ministry. Instead, we will move from scientific research to research and development. “
Specifications for the R1 supersonic design would include a gross weight of 121,250 pounds (large enough for between 4 and 18 passengers), a speed of Mach 1.8, an operating cap between 49,000 and 58,000 feet, and noise levels. sonic boom between 65 and 69 dBA.
The Supersonic Center team hopes that in 2025, the level of technologies will allow them to foresee the delivery of an SST2 with all-electric systems on board and a technical vision / augmented reality cabin for a single pilot (with functions from second crew member to be reassigned to some sort of artificial intelligence-based technology). The aircraft would also have a lift / drag ratio of 10, a ratio of 0.45 between empty weight and maximum take-off weight, a noise margin of 5 to 7 EPNdB within the limits of chapter 14 of the ICAO and a delay between major overhauls of 15,000 flights. hours.
Managing expectations, Russian industry stakeholders have indicated that they are unlikely to deliver a supersonic airliner or business jet with such performance until 2030.