'Union‑2') (GRAU index: 14A14) is a modernized expendable medium-lift launch vehicle and the seventh major version of the Soyuz rocket family.

[4] This upgrade allows the rocket to adjust its trajectory mid-flight, a capability the analog system lacked, eliminating the need for a rotating launchpad.

[16] Previously, engines were ignited pyrotechnically with a pair of small charges placed on a wooden stick inside each of the 32 combustion chambers.

[3][14] The extra burn time combined with the physically lighter and more capable digital flight control system increased payload capacity by 300 kilograms (660 lb).

[4] The Soyuz‑2.1a conducted its maiden flight on 8 November 2004, launching from Plesetsk Cosmodrome Site 43 with a boilerplate payload simulating a Zenit-8 spy satellite.

Fuelling of the rocket was underway at the time, and all launch complex equipment and onboard preliminary checks had proceeded without incident.

Following successful ground testing, a naphthyl (Russian: нафтил) fueled Soyuz‑2.1b launch took place on 22 October 2022 at Vostochny.

Naphthyl is an environmentally safe hydrocarbon fuel with fewer aromatic compounds than kerosene, which also slightly improves engine performance.

There are only minor differences in thermal properties, viscosity, and surface tension, so this did not require significant engine changes.