Blok DM [1]
Country of origin
Used on
General characteristics
Height
6.28 m (20.6 ft)
Diameter
3.70 m (12.1 ft)
Gross mass
17,360 kg (38,270 lb)
Propellant mass
15,220 kg (33,550 lb)
Empty mass
2,140 kg (4,720 lb)
Associated stages
Family
Blok D
Derived from
Blok D
Derivatives
Comparable
Launch history
Status
Retired
Total launches
66
First flight
1974-03-26
Last flight
1988-05-06
Launch date
Blok DM
Powered by
Maximum thrust
83.61 kN (18,800 lbf)
363.5 s (3.565 km/s)
Burn time
630 seconds
Propellant
Blok D (Russian: Блок Д meaning Block D) is an upper stage used on Soviet and later Russian expendable launch systems, including the N1, Proton-K and Zenit.[2]
The stage (and its derivatives) has been included in more than 320 launched rockets as of 2015[update].[3] By 2002 its modification Blok DM had a 97% success rate in 218 flights since 1974, and 43 successful missions in 1997–2002.[4][5]
The stage was developed in the 1960s as the fifth stage ('Д' is the fifth letter in the Cyrillic alphabet) for the powerful N1 rocket used in the Soviet crewed lunar programs. The stage first flew in March 1967 while testing the Zond spacecraft as a part of those programs. During crewed lunar flight Blok D would be used for mid-course corrections on the flight to the Moon, then to place the lunar orbiter and lander into a lunar orbit, and decelerate moon-lander out onto its landing trajectory.[6]
Blok D was also included as fourth stage of Proton-K and as such flew on uncrewed Soviet missions to Moon, Mars (Mars 3) and Venus. It was used in the Proton-K configuration of the rocket and is still in use in the newer Proton-M variant (along with the Briz-M).
Blok DM also flies as the third stage for the Zenit-3SL rocket, which is used by the Sea Launch project to launch geostationary satellites. In 2002 a Blok DM3 failed in the attempted launch of Astra 1K.
The stage uses liquid oxygen (LOX) and kerosene as propellants, and has one single-chamber RD-58 main engine. The LOX tank has a spherical shape; the kerosene tank is toroidal, inclined to 15 degrees for better fuel extraction, with the engine mounted in the center of torus. Tanks include the first pump stage for the engine; the main pump is mounted on the engine.
Blok D weighs 3.5 tons during liftoff, but some parts are jettisoned and the dry mass in space is 2.5 tons. It has 5.70 meters length and generates 83.300 kN thrust for 600 seconds burn time. Blok D was modified as Blok DM in 1974, with 11D-58S engine. The unit cost is $4 million.[7]
As of the early 1990s, the ullage rockets discarded just before the final burns by Block DM fourth stages on Proton launches constituted the largest single group of soviet propulsion systems to have suffered disintegrations contributing to space debris.[8]
Since 1990, all variations of this stage have been built in the Krasnoyarsk Machine-Building Plant.[9]
RKK Energia, the company that created Blok D, used it as a platform for many modifications over many years for different purposes; for example, the main propulsion unit on Buran started as a modification of the Blok D.[10]
Variant
First flight
Last flight
Launches
Rockets
Remarks
Blok D
1967
1976
44
Blok D-1
1978
1989
10
Mostly used for launches to Venus
Blok D-2
1988
1996
3
Launched Fobos 1, Fobos 2 and Mars 96
Blok DM
1974
1990
66
Blok D modification for Earth-based orbits
Blok DM-2
1982
2012
115
Used with Proton-M for GLONASS launches [1]
Blok DM-2M
1994
2005
15
Enhanced payload thanks to the use of higher performance Syntin fuel instead of RG-1. Powered by the RD-58S engine.
Blok DM-5
1997
2002
2
Used for low Earth orbit launches with Arkas satellites
Blok DM1
1996
1996
1
Commercial Blok DM-2, only used for one launch, with Inmarsat-3 F2
Blok DM2
1997
2002
4
Commercial Blok DM-5, used for Iridium and INTEGRAL launches
Blok DM3
1996
2006
25
Commercial Blok DM-2M
Blok DM4
1997
1997
1
Commercial Blok DM-2M, only used to launch Telstar 5
Blok DM-SL
1999
2014
36
Used in Sea Launch missions, some flights use a version with stretched fuel tanks
Blok DM-SLB
2008
2013
5
Used in Land Launch missions and other commercial Zenit-3SLB flights from Baikonur
2010
active
4
Intended as a replacement for Blok DM-2 and DM-SL/SLB, first flew in 2010, only used on Proton
2021
active
1
Modification of 11S861-03 (DM-03) for Angara A5
References
Active
Planned
Retired
Launch vehicles and
ascent/upper stages
Other hardware
LOK (7K-LOK/L1E) test missions
LK Lander (T2K) test missions
The † sign designates failed missions. Italics designates cancelled missions.
