The body of the descent module housed two containers for the parachute system,
which were in the form of elliptical cylinders. The larger of the two was intended for
the main parachute system and the smaller—for the backup system.
The parachute bundles are pushed with great force into the cramped
containers after the entire descent module has undergone heat treatment in a
special autoclave at a temperature of several hundred degrees to polymerize the
thermal protective coating. Before this, the openings of the empty containers
must be covered with flight lids since, being part of the exterior surface of
the descent module, they have the same thermal protective coating. During
descent, upon reaching an external pressure that corresponds to an altitude of
9.5 kilometers, a special pressure unit issues the commands to jettison the lid
of the main parachute system (OSP). After the parachutes are packed and
the lids closed, the containers are airtight and normal atmospheric pressure is
maintained inside them. When the container lids are jettisoned, the internal
pressure [of the container] drops abruptly to the value corresponding to an
altitude of 9.5 kilometers. The internal pressure of the descent module, which is
close to 1 atmosphere, acts on the body of the container. Because of the pressure
differential, compressive force acts over the entire surface of the container. The
jettisoned lid sweeps the drogue parachutes into the main stream; these, in
turn, pull out the braking parachute. The timing mechanism counts down a
delay of 17 seconds needed for the braking parachute to balloon open and
decelerate the descent module to the designated descent speed. Responding to
the command issued after 17 seconds, the braking parachute begins to pull the
bundle containing the main parachute out of the container. After the canopy of
the main parachute enters the stream, the braking parachute flies away with the
bag in which the main parachute was stowed.
...
The Soyuz landing system underwent thorough testing at the Air Force firing
range near Feodosiya. Descent module mockups with standard parachute systems
and our standard automatics were dropped from airplanes five times. We studied all
the glitches that occurred during these drops and modified the systems repeatedly.
Finally, we had the experience of landing the two previous 7K-OKs. Vehicle No.
1 (Kosmos-133) landed successfully using the ZSP when the emergency recovery
system was actuated, and vehicle No. 3 (Kosmos-140) came down onto the ice of the
Aral Sea, and there were no complaints about its parachute system.
...
On impact with the ground, there was an explosion and a fire started. The
descent module tanks still contained around 30 kilograms of concentrated
hydrogen peroxide, which had served as the gas for the guided reentry system
engines. It doesn’t just burn; it expedites the combustion of anything that
isn’t burning by giving off free oxygen as it breaks down. Due to the off-
nominal high rate of descent, rather than being jettisoned at an altitude of 3
kilometers, the front shield was jettisoned right at ground level. The command
to power up the gamma-ray altimeter was not executed, and consequently, the
command to start up the soft landing engines was not issued either. Impact
with the ground was so violent that the depression that was formed was more
than a half-meter deep. Local residents were the first to arrive at the crash site.
They tried to smother the fire by throwing dirt on it. When the helicopters
of the search and rescue service landed, fire extinguishers were used. When
Kamanin arrived, he demanded before all else that they search for what
remained of Komarov. His burnt remains were immediately sent to Orsk.
The main parachute was melted inside the container. The drogue, braking,
and backup parachutes were intact.
...
According to the commission’s findings, the most probable cause of the
main parachute’s failure to deploy was the insufficient force of the braking
parachute. Because the main parachute system’s braking parachute had
not been jettisoned, it created an aerodynamic shielding effect preventing
the backup parachute’s canopy from opening up. The possibility of their
simultaneous operation had not been looked at before. The commission
explained that the reason for the insufficient force of the braking parachute
was that, due to the pressure differential, the OSP container had deformed
and constricted the parachute bundle so that the amount of force needed to
pull it out of the container was significantly greater than the pull generated
by the braking parachute. When asked why this hadn’t been noticed during
all the developmental testing drops, the responses were not very convincing.
Regarding 7K-OK vehicle No. 3 (Kosmos-140), there had been no pressure
differential, since after the bottom of the descent module burned through,
the spacecraft had depressurized. During the work of the commissions, they
were unable to provide a convincing explanation for the normal operation of
the OSP during test drops from airplanes.
