Important Zvezda Laboratory File Report Of Main Defects of Lunar Spacesuit Krechet No. 12 Signed by Chief Designer of Zvezda Alekseev

Important Zvezda Laboratory File Report Of Main Defects of Lunar Spacesuit Krechet No. 12 Signed by Chief Designer of Zvezda Alekseev


Zvezda Laboratory file report of  the main defects found in laboratory test with Soviet Moon Lunar Program spacesuit Krechet and TBK-10.

Important 6 typed pages ( 11.1/2" x8") document, heavily notated, signed by Chief designer of the Zvezda plant Alekessev S.M., and many others leading constructors and engineers of Zvezda, who participate in development of Soviet lunar spacesuit "Krechet".


The main defects found in laboratory tests

with Spacesuit “Krechet” No.12 in TBK-10

1. The cleanliness is not observed when assembling the water tank and the pipes connecting the tank with the sublimator, and the water system (KVO and hoses).


When washing KVO, which came from the workshop, was found dirt. When disassembling the tank after the tests, dirt is also found inside the tank.

2. The operating time of the sublimators was 16-25 hours. In the process of testing, 3 sublimators were clogged up and out of order ( No.1, No.7 and No.6).


he reason (presumably) is dirt in the systems

3. The design of the tank eliminates the possibility of effective washing it. In the tank there is only one choke with a diameter of 2-3 mm.

4. The tank is charged with water through a water system (KVO, hydro accumulator), i.e. it creates an additional source of contaminated water in the system into the tank and from there to the sublimator.

Recommendations for No. 1-4:

Tank it is purposefully charged with water from a separate nozzle. Hydraulic connections between water in the tank and water in the KVO in this case should not be. In the drawings of products entering the water system, there must be notes on the need for preparation (washing, drying, treatment with alcohol, etc.) according to a single procedure.

It is desirable to have 2 holes in the tank in order to allow the washing tank to be rinsed with running water.

5. IR-005 is connected parallel to the cartridge LP-10. At LP-10, with which experiments were conducted, a pressure drop of 15-20 mm occurred. At a flow rate of 150 ml / min.

For normal operation of IR-005, air must pass through it in an amount of 35 ml / min. Resistance IR-005 to this flow according to TU-30, the resistance of the filter-drier facing IR-005-20 mm. Of water. As a result, since the total resistance of this branch is 50 mmHg, an inflow of about 10 ml / min can pass through IR-005. It is necessary either to remove the nozzle in the filter-drier and to increase the nozzle in IR-005, or to connect IR-005 using a section on which there is a large differential pressure.

There is a contradiction in the pressures: on the one hand for triggering the alarm of supplying a large flow of oxygen, the pressure O2 after the nozzle in the remote control should drop to 2.8 atm, and at the same time it should remain equal to 4.5 atm to supply the total pressure to the injector. It is advisable to install the nozzle in the DU in the other line in such a way that the signal is triggered when a large supply of O2 is switched on to compensate for leaks, but the injector receives full pressure after the gearbox.

Compensators for leaks KP-90A (No.2) and KP-90B( No.2) are unstable. At those heights, according to which the small feed should work, can turn on for a while (different for different checks, sometimes for 10-15 minutes or more) and a large feed. For example, in KP-09A at an altitude of 7.3 km to 12 liters / min, while at an altitude of 7.3-8.2 km there should be a flow of 2.4-3.2 l / min.

The KP-90B is also unstable. On the system, this is reflected as follows: it is impossible to go from 0.4 pressure in the SK to a pressure of 0.27 kg / cm^2 when the remote control knob is fed from position “0.4" through the neutral position “0.27".

The O2 intake through the valve operating in the neutral position is of the order of 12 ml / min, and KP-90A including a large feed at pressures in the 0.4-0.27 kg / cm^2 gap (the nominal inclusion should be 0.22 kg / cm^2) compensates for leakage through the remote control valve DU.


Pressure in the SK can not be made below 0.38 kg / cm^2.

Such a work of the compensators is probably due to the fact that aneroids work in jumps. It is possible that it is necessary to make compensators not with two, but with three or four aneroids, so that each aneroid works only on one pressure.

8. In the process of testing, the nozzle on the perp valve was clogged twice, only the condensate, passed through the metal-ceramic dehumidifier, which is a good filter, enters the differential valve. This is explained by the fact that the nozzle here must be very small. Clogging the nozzle leads to unexpected and unpleasant consequences condensate accumulates in the tube under the moisture collector, which has a u-shaped shape and locks the flow of air. For an almost complete cessation of air consumption with one fan running, 100-120 g of condensate is sufficient. The termination of consumption will result in the accumulation of CO2 to unacceptable concentrations and may be unnoticed, as the fan continues to operate.

It is necessary to increase the reliability of condensate drainage from the tube under the moisture collector, and to develop a more reliable nozzle on the retaining valve.

9. Aneroid starters (2 starters were used during the tests) are unstable. First, when working in the system, a very large hysteresis is affected in the actuation of the starter. The starter, which is adjusted to open at 0.23 atm, accumulates only at 0.32 ata. As a result, in the sublimation gap, the pressure of compression is maintained with a spread from 0.2 to 0.35 ata. This makes it difficult for the dehumidifier to work. When the pressure regime in the SK is 0.27 atm, the condensate in the sublimator may not go.

In addition, spontaneously one aneroid increased the opening pressure, and there was a self-priming of the nozzle of the starter.


10. Sublimators at pressures below 0.2 ata may not work efficiently.

Recommendations for No.9-10.

It is necessary to develop a starter with a smaller hysteresis with a more reliable nozzle.

The pressure regulator of the overpressure valve type (at 0.07 ati below the pressure in the SK) is most favorable for the operation of the dehumidifier. In this case, the pre-valve is optional. Requires, perhaps, only a check valve for condensate.

11. The accumulator, tested in the system, had a small pressure range at a pressure below 0.65 ata, including the water flow in the KVO, and at a pressure above 0.75 ata, it discharges water from the KVO into the tank. In addition, the accumulator was unstable. Given that the unit in this form only worsens the work of the system, in further tests it was turned off. The pressure in the system was maintained manually, and the tank was charged bypassing a yearly accumulator through a special pipeline.

12. The water flow sensor showed inaccurate and unstable readings. This is explained by the fact that in the water system it was almost always repacked on well-vacuum water. It is necessary to correct TK, taking into account that water can be either vacuum or with bubbles in the system.

13. In the wiring diagram, the polarity of the flow sensor switch did not match this model. As a result, the sensor failed during one of the connections. In order to increase the reliability of the meter's products and IR-0005, blocking is desirable, eliminating the possibility of failure of these devices in case of accidental incorrect connection.

 14. Sealing in the place of docking of Krechet and the Caspi by the air contour is unsatisfactory. This leads to the fact that the main air flow can go past the internal distribution of ventilation. More reliable sealing is necessary.

15. The filter on the suction pipe of the pump (cell 20-50μ) was a huge hydraulic resistance, and very quickly clogged up. A filter with a grid of 0.8 mm protects the pump reliably.

16. The handle of attachment KAB-450 is weak. It's broken with a small turning force.

17. Oxygen tubes went out of order:

a) In the place of fastening SK

b) Tube, strangling from the DU to KP-90B (to KP-90A barely holds).

It is necessary:

a) Fastening of the tube in the bar to make it nonrigid, eliminating the stress state

  b) If possible, do not use pipes with a wall thickness of 0.5 mm.


18. Minor imperfections due to lack of inspections in the drawings and negligence of the workshop:a) The gas return connection from IR-0005 to the exchanger was clogged.

b) There were O2 leaks on the choke on the side block OPK-19

c) A nozzle on the filter drier is clogged

d) The filter drier is not sealed

e) The nozzle on the choke to IR-0005 is clogged

f) Rubber ring on the dehumidifier comes from the workshop cut off

19. Inconvenience in testing:

a) Without removing the heat exchanger, the dehumidifier is not removed (small clearance to the housing)

b) It is very difficult to become a partition between Kaspi and Krechet, as it has a complex configuration. Do not need a ledge under the duct.

c) In the process of testing it is impossible to measure the pressure after the gear reducer KP-43 without special adaptation


Deputy Head of Department       Svershek ( signature)

Leader of the team No. 112        Kubar ( signature)

Leading Engineer                       Sharipov ( signature)


Handwritings follow up by leading engineer Braverman:


"All remarks on the topic of the team 28 were eliminated during the experiments on Krechet No. 12 in the working order, and also on the basis of notices of defects from the department. It is not clear why the above-mentioned work of the hydraulic accumulator does not evoke confidence in the hydraulic capacity of the hydraulic system.


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