|Country of origin||Ukraine|
|Height||39.95 m (131.1 ft)|
|Diameter||3.0 m (9.8 ft)|
|Mass||198,250 kg (437,070 lb)|
|Family||R-36 / Tsyklon|
|Launch sites||Alcântara ACS Pad|
|First stage – 11K69|
|Engines||1 × RD-261 + RD-855 Vernier engine|
|Thrust||2,970 kN (303 tf)|
|Specific impulse||300.4 s (2.946 km/s)|
|Burn time||119 seconds|
4 / UDMH
|Second stage – 11S692|
|Engines||1 × RD-262 + RD-856 Vernier engine|
|Thrust||995 kN (101.5 tf)|
|Specific impulse||314 s (3.08 km/s)|
|Burn time||162 seconds|
4 / UDMH
|Engines||1 × RD-861K|
|Thrust||76 kN (7.8 tf)|
|Specific impulse||325 s (3.19 km/s)|
|Burn time||450 seconds|
4 / UDMH
The Tsyklon-4, also known as Tsiklon-4 and Cyclone-4, was a Ukrainian carrier rocket which was being developed for commercial satellite launches. Derived from the Tsyklon-3, it had a new third stage, a larger payload fairing, and a modernised flight control system compared to its predecessor. The control system had been developed by JSC Khartron.
Tsyklon-4 was a three-stage-to-orbit expendable launch system, built on the successful Tsyklon-3 rocket and using improved versions of that rocket's first two stages. The new features were mostly in the newly developed third stage:
Tsyklon-4 would have improved the fuelling system, allowing safe capture of toxic vapours from the vehicle's hypergolic propellant system.
The launch system would have been able to deliver up to 5,250 kg (11,570 lb) to a 185 km (115 mi) orbit, 4,900 kg (10,800 lb) to a 400 km (250 mi) orbit, or 500 kg (1,100 lb) to a geosynchronous orbit.
Development began in 2002, with the maiden flight aimed for 2006. Following a series of production delays, this launch date slipped, and was estimated to occur some time after 2015.
Tsyklon-4 had been planned to launch from a proposed launch pad at the Alcântara Launch Center in Brazil, which would have given the rocket access to all orbital regimes. However, Brazil backed out of the partnership with Ukraine in 2015, citing concerns over the project budget, the ongoing financial situation in both countries, and the future of the commercial launch market. Yuzhnoye began developing a two-stage derivative of Tsyklon-4, the Cyclone-4M, for Maritime Launch Services, a Canadian launch service provider. The new rocket is scheduled to be in service by 2020.