Sukhoi Su-57 the Su-27. Extendible refueling probe is available to further increase its range. In the Su-57's design, Sukhoi addressed what it considered to be the F-22's limitations, such as its inability to use thrust vectoring to induce roll and yaw moments and a lack of space for weapons bays between the engines, and complications for stall recovery if thrust vectoring fails. The Su-57 will be the first operational aircraft in Russian Air Force service to use stealth technology. Similar to other stealth fighters such as the F-22, the airframe incorporates planform edge alignment to reduce its radar cross-section (RCS); the leading
Sukhoi-Gulfstream S-21 speeds. As of 2012, the project had not received any funding for the 2013-2025 development period and appeared to be cancelled. Sukhoi-Gulfstream S-21 Sukhoi-Gulfstream S-21 was a projected Russian-American supersonic business jet. In the early 1990s, Gulfstream Aerospace and the Sukhoi Design Bureau began a joint effort to develop a supersonic small business jet, code named the S-21. Due to questionable market demand for commercial supersonic air travel, commitment to the project weakened and delays mounted. Gulfstream eventually dissolved the partnership, although Sukhoi continued work on the S-21. The S-21 would be capable of sustained cruise at Mach 2+ and