Shenzhou Umbrella: Successful Protection Of Shenzhou 14 Return Capsule

The main umbrella covers an area of 1200 square meters and can cover three basketball courts after being fully deployed; The main umbrella is stretched over 70 meters in length and can span the football field

Late at night on December 4, Shenzhou No.14 returned home. During the live broadcast, the giant parachute opened in the air attracted people's attention. This is the "Shenzhou umbrella" developed by the 508 Institute of the Fifth Academy of China Aerospace Science and technology group. At present, it has protected the safe return of 14 spaceships.

On December 4, shenzhou-14 manned spacecraft successfully landed at Dongfeng landing site. (Photo by Lian Zhen, a reporter from Xinhua News Agency)

It is reported that designers have customized a set of three-stage parachute opening procedures for the spacecraft. First, two guiding umbrellas are connected in series, and then a deceleration parachute is pulled out by the guiding parachute. After working for a period of time, the parachute separated from the return capsule and pulled out the main umbrella of more than 1000 square meters at the same time. This series of actions can reduce the speed of the return capsule from the speed of high-speed rail to the speed of ordinary people running.

When the spacecraft's return module is lowered to a height of 1 meter above the ground, the gamma height control device at the bottom of the capsule sends out a signal to "command" the four reverse thruster engines on the spacecraft's return module to ignite, and give the capsule a force to lift upward, so that the landing speed of the capsule is further reduced, and the astronauts can land safely.

　　 The raw materials have been selected layer by layer

The success is hard won. The parachute development needs to go through 30 manufacturing processes, more than 20 packaging processes and more than 40 assembly processes. How was this giant parachute born? And how to pack it into the umbrella bag with a volume of less than 200 liters, which can be put into an ordinary household refrigerator?

According to 508 experts, the selection of raw materials for the giant parachute has gone through layer by layer selection. Firstly, special materials with high strength and light weight are selected according to the design parameters. After the materials are in place, they need to be retested to test the strength, elongation and air permeability of the materials to ensure that all indexes meet the design requirements. Before processing, the apparent quality of the materials should be further checked. The inspectors will check the appearance of the materials in good condition under the light of the cloth inspection device.

The raw materials are then cut into parts of different sizes and shapes. For silk materials, before cutting, the material should be spread out and laid aside for a period of time to remove the stress of the material itself, and then cut according to the process template. During cutting, the staff will pay special attention to the direction of silk thread to ensure that the direction of silk thread is consistent with the direction of product stress. For the rope and belt materials, the process personnel will give different loading forces according to different types and specifications, so as to release the stress of the material itself, so as to effectively ensure the consistency of the cut products. The typical ring sail parachute is selected for the giant parachute, which has the advantages of high reliability and strong tear resistance. The canopy composed of red and white rings and sails plays an important role. The giant parachute can effectively reduce the descent speed of the re-entry module, because it can obtain a larger resistance area when it is deployed. However, the initial state of the parachute is a small trapezoidal silk fabric, which needs to be stitched together by the staff.

When sewing, the staff will control the quality of the stitches, not only to ensure the density of the stitches, but also to ensure the width of the stitches, distance from the edge, stitching, etc. The canopy is better than the "double eaves roof" when building a house. Each layer of ring or sail is similar to the tenon structure.

Shenzhou-13 manned spacecraft re-entry module successfully landed in the predetermined area of Dongfeng landing site. (Photo by Lian Zhen, a reporter from Xinhua News Agency)

　　 The length of parachute rope is more than 40 meters

After the giant parachute ring and sail parachute are sewn together, it seems that they are connected into a line. However, as a surface of 1200 square meters, it is necessary to combine the stitched rings and sails with the help of the radial and latitudinal belts of the parachute. The radial belt is better than the "four beams and eight columns" when building a house. The radial belt is the main structure to bear the radial opening tension of the canopy, while the latitudinal belt is the main structure to bear the weft opening tension of the canopy and maintain the inflatable shape of the canopy. The processed radial and latitudinal belts can ensure the parachute strength.

The rope of giant parachute bears the load of parachute opening when it is working, which is the main structure to transfer the load to the sling and return cabin. However, the length of the giant parachute rope is more than 40 meters, and there are 96 pieces. In the process of processing, how is it orderly and not twined?

In the preparation process, the staff of 508 Research Institute first installed and sewed the umbrella rope at the same end, then arranged the umbrella rope into the comb rope clamp according to the number sequence through a tool called comb rope clamp, held the comb rope clip, straightened it from head to tail, and then installed the umbrella rope at the other end in turn, so that the roots can be clearly defined.

Shenzhou spaceship parachuting scene. (photo provided by 508 Institute of the Fifth Academy of Aerospace Science and Technology Group)

　　 The giant is light

Although the giant parachute is a huge object, it is very light. It weighs less than 100kg. After being folded up, the volume of the parachute into the umbrella bag is less than 200l, which can be stuffed into the ordinary household refrigerator. However, the soft parachute is not put in the re-entry module at will, but the parachute's canopy, parachute rope and connecting sling are put into the parachute bag in order to maintain a certain geometric shape. This involves an irreversible task, which sounds simple and highly technical - umbrella wrapping.

According to reports, the umbrella should be dried before formal wrapping to release the internal stress of the material and clean up the surplus materials; Then fold the canopy, comb the parachute rope, arrange the parachute bag, load the parachute, pack and weigh in turn. Finally, the 1200 square meter umbrella is turned into a 200 liter umbrella bag, and the final work before entering the cabin is completed.

(source: Xinhua news agency, China News Network)