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1.6.2 L3 Notable Features

 * Not a Soyuz derivative per se, though it was developed as part of the same program which produced the Soyuz-derived L1 and L2 vehicles. L3 was to have been used with the L2 vehicle.
 * Flight-test version of the L3 was called T2K. It was launched for Earth-orbital tests on a modified Soyuz rocket with an enlarged (“large caliber”) launch shroud. T2K had its landing legs replaced by two units for returning systems telemetry to Earth.
 * For lunar landing missions, was to be launched on a three-stage N-1 rocket, within a shroud, as part of the LRS. The LRS consisted of Block D and Block G rocket stages, the L3 lunar lander, and the L2 command ship.
 * The Block D stage carried out midcourse corrections en route to the Moon and braked the L2 and L3 into lunar orbit. After lunar orbit insertion, a single cosmonaut exited the L2 through the hatch in its living module, traversed the length of the L2 with the aid of a mechanical arm, and entered the L3 through a port in the shroud enclosing it. The shroud then fell away as the Block D and L3 separated from the L2.
 * Restartable rocket motor on the Block D provided most of the DV for powered descent to the lunar surface. The Block D was to be depleted and discarded about 1 to 3 km above the surface. After it was discarded, the Block D crashed on the lunar surface a short distance from the L3 touchdown point.
 * ?Had one single-nozzle main engine on its longitudinal axis, one two-nozzle backup engine, and four verniers. The lozenge-shaped propulsion unit was dubbed the Ye unit. Loaded with


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 * N2O4 and UDMH propellants, the Ye unit weighed approximately 2250 kg (half the weight of the L3). N2O4 was stored in a toroidal tank surrounding the engine units.  This fuel load gave the L3 about 1 min of flight time before it began to cut into its ascent reserves.


 * Control system was the first in the Soviet program based on an onboard computer. Inputs were derived from a three-axis gyrostabilized platform, landing radar, and a collimating sight. The cosmonaut would use the sight to spot the selected landing site, then input the coordinates to the computer. Computer commands were verified using Sun and planet sensors.
 * Two 40-kg thrusters gave pitch control; two more gave yaw


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 * control; and four 10-kg thrusters gave roll control. The system was exactly duplicated on a separate control circuit to provide redundancy.


 * Lone cosmonaut stood before a large, round, downward-angled window; controlled flight manually using a control panel located to the right of the window and control sticks. A smaller window faced upward to provide visibility during docking.
 * Cabin atmosphere was oxygen/nitrogen at 560 mm/Hg, with slightly less nitrogen than the terrestrial mix normally used in Soviet spacecraft.
 * Relied on five chemical batteries for its electricity. Two were located on the ascent portion of
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