In Russia, the wait for a commercial supersonic transport revival stretches much longer than 10 years. Aeroflot grounded and subsequently retired the Tupolev Tu-144 fleet less than two years after service between Moscow and Almaty began in 1976. The brief and somewhat perilous chapter of Russian supersonic flight was over – 25 years before the last flight of the Concorde.
Like its counterpart in the West, however, Russia’s aerospace industry was working on replacements almost immediately after the Tu-144 stopped flying passengers.
Progress has been slow, but both the Sukhoi and Tupolev design bureaus still appear committed to designing and producing a supersonic jet. Although financial support and certain technical details remain unclear, a broad picture has emerged of a long-term, dedicated effort to deliver a family of supersonic aircraft for commercial transport.
A supersonic aircraft is one of the major research efforts of the Central Aerohydrodynamic Institute (TSaGI), the equivalent to NASA’s Langley Research Center. TSaGI has provided wind tunnel access to both design bureaus, while also releasing its own interpretation of a supersonic design in 2012.
As one of Russia’s specialists in designing large and supersonic aircraft, Tupolev is known to be quietly working on the Tu-444 supersonic business jet. The last public images of the concept appeared in the Russian press five years ago and depicted a 10-passenger twinjet.
Sukhoi, on the other hand, has been far more outspoken about its interests in the supersonic sector, and provided a comprehensive update on its progress at the MAKS air show in late August outside Moscow.
The company’s concept for a supersonic jet has evolved significantly since 1989, when then chief designer Mikhail Simonov launched an effort to design a concept aircraft that became known as the S-21. Gulfstream agreed at the 1989 Paris air show to participate in the programme and the designation was amended to the S-21G.
The collaboration between the two companies broke down in the late 1990s, and both companies moved on to work on independent projects. Gulfstream chief engineer Pres Henne secured dozens of patents for a low-boom supersonic aircraft called the “Whisper”.
Meanwhile, Sukhoi scrapped the S-21 concept as evolving pollution and noise emission regulations rendered the design unfeasible.
It was replaced in 2001 with an all-new design featuring a dihedral wing, a highly sloped needle nose and forward canards. A pair of underwing engines completed the configuration, which Sukhoi now describes as a “medium sonic boom” design.
By 2003, Sukhoi had progressed to develop a “low sonic boom” aircraft. Instead of wing-mounted engines, the low-boom concept used two engines mounted at on top of the aft fuselage and beneath a vertical tail.
The second half of the last decade was spent analysing the concepts in various wind tunnels, including at TSaGI. Sukhoi was also selected by Dassault to participation in an EU supersonic research programme called HISAC (environmentally-friendly high-speed aircraft).
The goals of HISAC included “reducing” the sonic boom overland and producing take-off noise 8dB lower than ICAO’s Chapter 4 standards. The latter proved to be useful, as ICAO may require any supersonic designs to comply with Chapter 14 standards after 2020, which mandate a 7dB reduction compared to Chapter 4.
Since the conclusion of HISAC in 2009, the details of Sukhoi’s research activity on supersonic aircraft have not been made public.
Sukhoi’s presentation at MAKS revealed that it has developed a family of supersonic vehicle concepts over the last three years, including a 50-seater in a low-boom configuration.
Previous documents released by Sukhoi have identified the 2:1 bypass ratio variant of the Rolls-Royce Trent 800 core as the preferred engine for the aircraft. The engines were displayed without an afterburner, implying a supercruise capability.