Engineering:Soyuz-U

Short description: Soyuz rocket design variant

Soyuz-U

A Soyuz-U on the launchpad for the Soyuz 18 mission
Function	Orbital carrier rocket
Manufacturer	TsSKB-Progress
Country of origin	Soviet Union
Size
Height	Soyuz-U: 51.1 m (168 ft) Soyuz-U/Ikar: 47.3 m (155 ft) Soyuz-U/Fregat: 46.7 m (153 ft)
Diameter	3 m (9.8 ft)
Mass	Soyuz-U: 313,000 kg (690,000 lb) Soyuz-U/Ikar: 308,000 kg (679,000 lb) Soyuz-U/Fregat: 308,000 kg (679,000 lb)
Stages	Soyuz-U: 2 Soyuz-U/Ikar: 3 Soyuz-U/Fregat: 3
Capacity
Payload to LEO	Baikonur: 6,900 kg (15,200 lb) Plesetsk: 6,700 kg (14,800 lb)
Associated rockets
Family	R-7 (Soyuz)
Derivatives	Soyuz-U2 Soyuz-FG
Launch history
Status	Retired
Launch sites	Baikonur Sites 1/5 & 31/6 Plesetsk Sites 16/2, 41/1 & 43/3 & 43/4
Total launches	786
Successes	765
Failures	22
First flight	18 May 1973
Last flight	22 February 2017 (Progress MS-05)
Notable payloads	Soyuz spacecraft Progress spacecraft
Boosters – Blok-B,V,G,D
No. boosters	4
Length	19.6 m (64 ft)
Diameter	2.68 m (8.8 ft)
Empty mass	Soyuz: 3,800 kg (8,400 lb)
Gross mass	43,400 kg (95,700 lb)
Engines	RD-117
Thrust	Sea Level: 838.5 kN (188,500 lbf) Vacuum: 1,021.3 kN (229,600 lbf)
Specific impulse	Sea Level: 262 s (2.57 km/s) Vacuum: 319 s (3.13 km/s)
Burn time	118 seconds
Fuel	LOX/RG-1
First stage – Blok-A
Length	27.10 m (88.9 ft)
Diameter	2.95 m (9.7 ft)
Empty mass	Soyuz: 6,550 kg (14,440 lb)
Gross mass	Soyuz: 99,500 kg (219,400 lb)
Engines	RD-118
Thrust	Sea Level: 792.5 kN (178,200 lbf) Vacuum: 990.2 kN (222,600 lbf)
Specific impulse	Sea Level: 255 s (2.50 km/s) Vacuum: 319 s (3.13 km/s)
Burn time	290 seconds
Fuel	LOX/RG-1
Second stage – Blok-I
Length	6.70 m (22.0 ft)
Diameter	2.66 m (8.7 ft)
Empty mass	Soyuz: 2,410 kg (5,310 lb)
Gross mass	Soyuz: 25,200 kg (55,600 lb)
Engines	RD-0110
Thrust	297.9 kilonewtons (67,000 lbf)
Specific impulse	325 seconds
Burn time	270 seconds
Fuel	LOX/RG-1
Upper stage (optional) – Fregat
Length	1.5 m (4.9 ft)
Diameter	3.35 m (11.0 ft)
Empty mass	930 kg (2,050 lb)
Propellant mass	5,250 kg (11,570 lb)
Engines	S5.92
Thrust	19.85 kilonewtons (4,460 lbf)
Specific impulse	333.2 seconds
Burn time	1100 seconds
Fuel	N2O4/UDMH
Upper stage (optional) – Ikar
Length	2.56 m (8.4 ft)
Diameter	2.72 m (8.9 ft)
Empty mass	820 kg (1,810 lb)
Gross mass	3,164 kg (6,975 lb)
Engines	S5.144/17D61
Thrust	2.94 kN (660 lbf)
Specific impulse	307 seconds
Fuel	N2O4/UDMH

The Soyuz-U launch vehicle was an improved version of the original Soyuz rocket. Soyuz-U was part of the R-7 family of rockets based on the R-7 Semyorka missile. Members of this rocket family were designed by the TsSKB design bureau and constructed at the Progress factory in Samara, Russia (now a united company, TsSKB-Progress). The first Soyuz-U flight took place on 18 May 1973, carrying as its payload Kosmos 559, a Zenit military surveillance satellite. The final flight of a Soyuz-U rocket took place on 22 February 2017, carrying Progress MS-05 to the International Space Station.

Soyuz-U was in use continuously for almost 44 years. Production of R-7 derived launch vehicles peaked in the late 1970s-early 1980s at 55–60 a year. Soyuz-U held the world record of highest launch rate in a year in 1979 with 47 flights until this was beaten by SpaceX's Falcon 9 in 2022. Over its operational lifetime, the Soyuz-U variant flew a total of 786 missions, another world record. Soyuz-U has also been one of the most reliable launchers, with a success rate of 97.3%. The rocket had a streak of 112 consecutive successful launches between 11 July 1990 and 5 May 1996.

Development

The earlier Soyuz 11A511 was the first attempt at creating a standardized R-7 core in place of the numerous variations that had been used up to 1966. Starting that year, the 11A511 Blok I and strap-on boosters were added to the Voskhod (11A57), Vostok-2 (8A92), and Molniya-M (8K78M) vehicles as well as minor R-7 variants flown once or twice for specialized payloads.

The uprated 11A511U core was introduced to the R-7 family in 1973, yielding the carrier rocket variant named Soyuz-U, although adoption across the board was not complete until 1977 when the existing stock of 11A511-derived boosters was used up.

Versions

Two versions of Soyuz-U were fitted with an additional upper stage:

• Soyuz-U/Ikar with the Ikar third stage, produced by the Progress State Research and Production Rocket Space Center, TsSKB-Progress. Ikar is used to deliver various payloads with masses of 750 to 3,920 kg (1,650 to 8,640 lb) to heights of 250 to 1,400 km (160 to 870 mi). The performance of the Ikar upper stage is lower than that of the Fregat upper stage, but it is more precise in maneuvering and it can operate autonomously longer. This version was launched 6 times in 1999, carrying four GlobalStar satellites on each mission.
• Soyuz-U/Fregat with the Fregat third stage, developed and produced by Lavochkin Association in Khimki. This version only flew 4 times in 2000; the Fregat upper stage was subsequently flown regularly atop Soyuz-FG and Soyuz-2 boosters.

An older variant of Soyuz-U, the Soyuz-U2 launcher, first flown in 1982, had the same hardware as the basic Soyuz-U. Instead of standard RP-1, it used a high energy, synthetic version, Syntin, as the first stage fuel. This variant, mainly used to transport crew and cargo to the Mir space station, last flew in 1995, after production of Syntin ended due to cost reasons.

Soyuz-U was the basic platform for the development of the Soyuz-FG variant, which used an all-new first stage and took over crew transport to the ISS in 2002. Since 2013, both Soyuz-U and Soyuz-FG are gradually being replaced by the modernized Soyuz-2 launch vehicle.

Human spaceflight

The first use of a Soyuz-U to launch a crewed mission took place 2 December 1974, when the Soyuz 16 crew was launched in preparation for the Apollo–Soyuz Test Project (ASTP). Soyuz 19, which as part of the ASTP docked with the last Apollo spacecraft ever flown, was also launched by a Soyuz-U rocket.

On 6 July 1976, a Soyuz-U launched Soyuz 21, which took a crew of two to the Salyut 5 space station. Many subsequent space station crews were launched on Soyuz-U launchers. The final crewed mission to use the Soyuz-U was Soyuz TM-34, a Soyuz ferry flight to the International Space Station.

A spectacular accident occurred on 26 September 1983, when the launcher for the Soyuz T-10a mission was destroyed by fire on the launch pad. The crew was saved by activation of the launch escape system a few seconds before the explosion.

Missions after 2000

From 2000 until its retirement in 2017, Soyuz-U vehicles were used by the Russian Federal Space Agency primarily to launch Progress-M robotic cargo spacecraft on resupply missions to the International Space Station (ISS).

Although the Soyuz-U was generally very reliable, occasional failures occurred, such as the October 2002 launch of a Foton satellite which crashed near the pad at Plesetsk after the Blok D strap-on booster suffered an engine malfunction. One person on the ground was killed.

A Soyuz-U mission failed to launch Progress M-12M to the ISS on 24 August 2011, when the upper stage experienced a problem and broke up over Siberia. It was the first time a Progress spacecraft had failed to reach orbit. Another cargo ship, Progress MS-04, was lost on 1 December 2016 shortly after launch, likely due to a problem with the third stage of the Soyuz-U.

In April 2015, Soyuz-U was declared obsolete. Its production was stopped and the rocket was scheduled for retirement after launching the remaining vehicles with Progress cargo ships. The final flight was Progress MS-05, which launched from the Baikonur Cosmodrome on 22 February 2017, 05:58:33 UTC.

External links

• (PDF) Soyuz Launch Vehicle Users Manual
• Astronautix.com entry on Soyuz-U / 11A511U
• Astronautix.com entry on Soyuz-U2 / 11A511U2
• Russian Federal Space Agency about Soyuz-U
• Russian Federal Space Agency about Soyuz-U/Ikar
• Russian Federal Space Agency about Soyuz-U/Fregat
• Russian Federal Space Agency about Soyuz-U2
• LV's manufacturer TsSKB-Progress about Soyuz-U (in Russian)