Comparison of the first generation manned spacecraft

It is interesting to see how different people solve the same problem. Everyone has their own experience, their initial conditions, but when the goal and requirements are similar, the solutions to this problem are functionally similar to each other, although they may vary in a particular implementation. In the late 1950s, both the USSR and the USA began to develop manned spacecraft for their first steps into space. The requirements were similar - the crew was one person, the time spent in space - up to several days. But the devices turned out different, and, it seems to me, it would be interesting to compare them.

Introduction

Neither the USSR nor the USA knew what awaits man in space. Yes, in flying on an airplane you can reproduce weightlessness, but only lasting ~ 30 seconds. What will happen to a person with prolonged weightlessness? Doctors scared the inability to breathe, drink, see (supposedly the eye should lose its shape due to malfunctioning of the eye muscles), think (scared by insanity or loss of consciousness). The knowledge of high-energy cosmic particles led to thoughts of radiation damage (and even after the flights, terrible versions of radiation sickness of flying astronauts surfaced regularly in newspapers). Therefore, the first ships were designed for a short time spent in space. The duration of the first flights was measured in minutes, the next - in hours, or turns around the Earth (one turn - about 90 minutes).

Withdrawal Means

The main factor affecting the design of the ship was the carrying capacity of the launch vehicle. Both the two-stage R-7 and the Atlas could bring about 1300 kg into low Earth orbit. But for the Seven, they managed to work out the third stage in lunar launches of 1959 - block E, increasing the carrying capacity of the three-stage rocket to 4.5 tons. But the USA still could not work out the basic two-stage Atlas, and the first theoretically possible version of the Atlas Agen flew only at the beginning of 1960. The result was a joke - the Soviet Vostoks weighed 4.5 tons, and the mass of Mercury was comparable to the weight of Sputnik-3 - 1300 kg.

External structural elements

Let us first consider the outer part of the ships:


"East"


"Mercury"

Body shape

"Vostok" in the withdrawal area was under a discarded fairing. Therefore, the designers were not worried about the aerodynamic shape of the ship, and it was also possible to easily place antennas, cylinders, thermoregulation blinds and other fragile elements on the surface of the device. And the design features of the block "E" determined the characteristic conical "tail" of the ship.



Mercury could not afford to drag a heavy fairing into orbit. Therefore, the ship had an aerodynamic conical shape, and all sensitive elements such as a periscope were removable.

Heat protection

When creating the "East", designers proceeded from solutions that provide maximum reliability. Therefore, the shape of the descent vehicle was chosen in the form of a ball. The uneven distribution of weight ensured the effect of a “vanka-vstanka”, when the descent vehicle independently, without any control, was installed in the correct position. And thermal protection was applied to the entire surface of the descent vehicle. When braking against dense atmospheric layers, the effect on the surface of the ball was uneven, therefore, the thermal protection layer had a different thickness.


Left: flow around a sphere at hypersonic speed (in a wind tunnel); right: unevenly burned descent vehicle Vostok-1.

The conical shape of Mercury meant that thermal protection would be required only from below. On the one hand, this saved weight, on the other hand, the ship’s incorrect orientation when entering the dense atmosphere meant a high probability of its destruction. On the top of the ship was a special aerodynamic spoiler, which was supposed to turn the "Mercury" stern forward.


Left: cone at hypersonic speed in a wind tunnel, right: Mercury thermal protection after landing.

Curiously, the heat-shielding material was similar - in the "East" asbestos-impregnated with resin, on the "Mercury" - fiberglass and rubber. In both cases, a fabric-like material with a filler burned in layers, and the filler evaporated, creating an additional layer of thermal protection.

Brake system

The brake engine of the "East" was not duplicated. From a security point of view, this was not a good solution. Yes, the Vostoks were launched so that within a week they would naturally slow down on the atmosphere, but, firstly, already in flight Gagarin’s orbit was higher than the calculated one, which actually “turned off” this backup system, and secondly, natural braking meant landing anywhere from 65 degrees north latitude to 65 degrees south latitude. The reason for this is constructive - two rocket engines did not fit into the ship, and solid-fuel engines were not mastered then. Reliability TDU increased maximum design simplicity. There were times when the TDU gave a slightly lesser impulse than necessary, but there was never a complete failure.


TDU "East"

At Mercury, behind a heat shield, was a block of separation and braking engines. Both types of engines were installed in triplicate for greater reliability. Separation engines were turned on immediately after the launch rocket engines were turned off so that the ship moved away from the launch rocket to a safe distance. The brake motors started to go out of orbit. In order to return from orbit, one brake engine that worked was enough. The engine block was mounted on steel tapes and dumped after braking.


TDU "Mercury"

Landing system

In the Vostok, the pilot landed separately from the ship. At an altitude of 7 km, the astronaut ejected and parachuted independently. For greater reliability, the parachute system was duplicated.



At Mercury, the idea of ​​landing on water was used. Water softened the blow, and the large US fleet did not have difficulty finding a capsule in the ocean. To mitigate the impact on water, a special air bag-shock absorber was opened.



History has shown that landing systems turned out to be the most dangerous in projects. Gagarin almost got into the Volga, Titov landed next to the train, Popovich almost broke on the rocks. Grissom nearly drowned with the ship, and they searched for Carpenter for more than an hour and already began to consider him dead. In subsequent ships there was no pilot bailout, no shock absorber cushion.

Emergency rescue systems

The astronaut’s regular ejection system in Vostok could work as a rescue system in the initial part of the trajectory. There was a hole in the fairing for the astronaut's landing and emergency bailout. The parachute might not have time to open in the event of an accident in the first seconds of the flight, so a grid was stretched to the right of the launch pad, which was supposed to mitigate the fall.


Grid below in the foreground

At high altitude, the ship was supposed to separate from the rocket, using standard means of separation.
The Mercury system had an emergency rescue system, which was supposed to take the capsule away from a collapsing rocket from the start to the end of the dense layers of the atmosphere.

In the event of an accident at high altitude, a standard separation system was used.
Ejection seats were used as a rescue system on the Gemini, as well as on the Space Shuttle test flights. CAC in the style of "Mercury" stood on the "Apollos" and is still placed on the "Unions".

Orientation motors

Compressed nitrogen was used as a working fluid for orientation on the Vostok ship. The main advantage of the system was its simplicity - gas was contained in balloons and was released using a simple system.
The Mercury ship used the catalytic decomposition of concentrated hydrogen peroxide. From the point of view of the specific impulse, this is more advantageous than compressed gas, but the reserves of the working fluid at the Mercury were extremely small. By actively maneuvering, it was possible to spend the entire supply of peroxide in less than one revolution. But her stock had to be stored for orientation operations during landing ... Astronauts secretly competed among themselves who would spend less peroxide, and Carpenter, who was interested in photography, got into a serious alteration - he spent the working medium uneconomically on orientation and the peroxide ended up in the landing process. Fortunately, the altitude was ~ 20 km and no disaster happened.
In the future, peroxide as a working fluid was used in the first Soyuz, and then all switched to the high boiling components of UDMH / AT.

Thermoregulation system

The Vostoks used blinds that either opened, increasing the radiating area of ​​the ship, or closed.
At Mercury there was a system using water evaporation in a vacuum. It was more compact and lighter, but there were more problems with it, for example, in Cooper's flight, she knew only two states - “hot” and “cold”.

Internal structural elements

The internal layout of the ship "Vostok": The


internal layout of the ship "Mercury":

Toolbar

Toolbars most clearly show the difference in design approaches. Designers of rockets did the “East”, therefore its toolbar is characterized by a minimum of controls:


Photo


Left panel.


The main panel.

“Mercury” was made by former aircraft designers, and astronauts made efforts to ensure that the cabin was familiar to them. Therefore, there are many more controls:


Photography.


Scheme.

At the same time, the similarity of tasks gave rise to identical devices. Both in the Vostok and Mercury there was a globe with a clockwork, showing the current position of the device and the estimated landing site. Both the Vostoks and the Mercury had indicators of the stages of the flight - on the Mercury these are the “Flight Operations Management” on the left panel, on the Vostoks the indicators “Descent-1”, “Descent-2”, “Descent- 3 ”and“ Prepare for bailout ”on the central panel. Both ships had a manual orientation system:


Vzor on Vostok. If on the peripheral part the horizon is on all sides, and the Earth in the center moves from the bottom up, then the orientation towards braking is correct.


Periscope on the Mercury. Marks show the correct braking orientation.

Life supporting system

On both ships, the flight was carried out in spacesuits. In the "East", an atmosphere close to the earth was maintained - a pressure of 1 atm, oxygen and nitrogen in the air. At Mercury, the atmosphere was purely oxygen at reduced pressure to save weight. This added inconvenience - the astronaut needed to breathe oxygen in the spacecraft for about two hours before launching, during the removal it was necessary to bleed the atmosphere from the capsule, then close the ventilation valve, and open it again during landing to increase pressure along with atmospheric pressure.
The sanitary-hygienic system was more advanced in the Vostoks - flying for several days there was an opportunity to satisfy large and small needs. On the "Mercury" there were only urinals, a special diet saved them from big hygiene problems.

Electrical system

Both ships used battery power. The "Vostoks" were more durable, on the "Mercury" Cooper's daily flight ended in conditions of failure of a good half of the instruments.

Conclusion

Both types of ships were the pinnacle of the technology of their countries. Being the first, both types had both successful solutions and unsuccessful. The ideas embodied in the Mercury live in rescue systems and conical capsules, and the grandchildren of the East still fly - the Photons and Bions use the same spherical descent vehicles:

In general, the Vostoks and Mercury turned out to be good ships that made it possible to take the first steps into space, and avoided fatal incidents.