UPPER STAGES BLOCK DM AND BLOCK DM-SL

Upper stage Block DM is intended for transferring a spacecraft from a reference orbit to the target Earth satellite orbit and to Earth escape trajectories for interplanetary missions, while meeting customer requirements for attitude control and injection accuracy.
Upper stage Block DM design is based on Block D, which was originally developed under lunar program N1-L3 and the first time it successfully operated in flight was as a part of L1 complex (with Proton launch vehicle) on March 10, 1967. Upper stage Block DM features high reliability proven by more than 30 years of its operational history, and capacity for multiple burns of the main engine, which allows it to perform the required orbital maneuvers.
The design of upper stage Block DM embodies a modular principle. The core of the upper stage is the base module, which includes propellant tanks, engine, two propulsion units of the attitude control/ullage system, autonomous instrumentation bay and primary structure.
If the mass of spacecraft that can be delivered to orbit needs to be increased, the autonomous instrumentation bay, which houses the motion control system, can be removed from the upper stage, with control over the stage transferred to the spacecraft.
The upper stage operates on non-toxic propellant components: liquid oxygen + kerosene.
To settle propellant when starting the main engine in zero-g environment, a special starting-up system is used, which includes two propulsion units operating on high-boiling propellant components.
The upper stage is easy to operate.

Accuracy of SC Launches to Geostationary Transfer Orbit and High Elliptical Orbit Using DM Type Upper Stage For a Period Since 1996.

Upper stage Block DM was modified for the Sea Launch (DM-SL). The modification mostly consisted in matching interfaces between the upper stage and the payload unit on one hand and between the upper stage and Zenit-2S launch vehicle on the other hand.
Currently, this upper stage is used as a part of launch vehicles Proton (launched from Baikonur launch site) and Zenit (launched from Sea Launch system).

Principal characteristics			Upper stage Block DM-SL
	DM	DM-SL
The mass of the fully assembled upper stage structure, tons Full propellant supply, tons Main engine 11D58M thrust in vacuum, ton-force The number of main engine firings Mass of payload put into GEO, tons	3.2 15.1 8.5 up to 5 2.7	3.5 15.1 8.0 up to 5 2.5

Upper Stage L

The stage is designed of a propulsion compartment, a one-chamber engine 11D33 in a Cardan's suspension, and a structural truss assembly.
Fuels tanks of stage L are covered with application specific thermal insulation for protection against solar radiation exposure in a long-duration flight.
Special bellows allows the engine deflection up to 3° for yaw and pitch control. The roll is controlled via two nozzles of 10 kgf thrust each capable to deflect up to 45 and operating from an extra gas generator from which gas is simultaneously supplied to pressurize oxidizer and fuel tanks.
The engine is started in vacuum, following 1.5 hours of flight in the Earth orbit. Therefore, the stage is provided with an attitude control and stabilization system and an ignition unit to fire the engine in vacuum.
The stage accommodates a control system for stages I and L of LV Molniya.
The stage is being currently used in LV Molniya.