Under the gaze of everyone, the rocket drew a white smoke line in the blue sky. As the breeze blew, the smoke line began to gradually dissipate.
As for the rocket, it flew higher and higher, and in the end there was only a flickering bright spot left. If the sky had not been clear and transparent, it would have disappeared from everyone's sight.
"21070 meters, the rocket starts to descend!"
"The optical tracking observation team reported that the heat shield on the top of the rocket has separated and the guidance parachute has been thrown out."
"Pay close attention to the rocket's landing attitude!"
"The grid plate is open and the posture is normal!"
"21000, 20000, 19000..."
As the broadcast numbers gradually dropped, everyone could clearly see the whereabouts of the rocket again. The main rocket was like a daytime meteor, dragging a vague wake and falling to the ground.
"16000, the main parachute is thrown out!"
"The optical tracking observation team reported that all three main parachutes were opened and in normal condition."
Bang bang bang... Everyone in the control center and those watching this scene outside applauded enthusiastically. As long as the main parachute is opened, this means that the entire return experiment is more than half successful, and the next part is
Waiting for the rocket to land.
Wu Hao and the others could also see with the naked eye that the rocket was dragging three huge red and white parachutes and began to slowly descend. At this moment, everyone in the control center also ran out, and everyone looked up at the sky and stared.
The silhouette of the rocket slowly descending.
"Affected by the rising wind speed at high altitude, the rocket began to drift northwest."
"How much offset?"
"Estimated to be about one kilometer."
"Continue to observe closely, notify the ground recovery team, and prepare to go to the relevant areas to prepare for the whereabouts of the rocket."
After hearing this order, Wu Hao waved and said: "Let's go, let's go to the scene and have a look."
Zhang Jun nodded, then boarded an off-road vehicle with Wu Hao and flew towards the rocket's crash site.
Behind their car, there were also many other vehicles. Sitting in the car, Yu Chengwu urged the driver to hurry up and said with a walkie-talkie: "Anything can happen when the rocket lands. In addition, there are still some residues inside the rocket.
Less fuel. This is to prepare for the slowdown in reverse push for visa on arrival. Therefore, everyone is informed to maintain a safe landing distance to avoid possible dangers.
When it lands safely, immediately set up an isolation line. Except for professionals, no one else is allowed to get close. Especially Mr. Wu and Mr. Zhang, hold him, protect their safety, and don't let them get close."
After saying this, Yu Chengwu shouted at the driver in front of him: "Hurry up!"
To be honest, Wu Hao and the others felt uncomfortable in the car. While they leaned against the window and watched the rockets descending in the sky, they had to endure the bumps of the vehicle driving on the sand dunes.
Zhang Jun couldn't stand it after a few bumps. His face turned pale and he was trying to hold it back.
Fortunately, this time did not last long, and the vehicle stopped on the top of a higher sand dune. There were already many vehicles parked on this dune, and these were all members of the ground recovery team.
At this moment, the rocket was already very close to the ground, and it was only eight or nine hundred meters high by visual inspection. The approximate landing point was on the sand about one or two hundred meters in front of them.
At this distance, everyone can no longer move forward. Who knows if there will be any problems at this height of 500 to 600 meters.
"Mr. Wu, why are you running so fast?" Yu Chengwu got out of the car panting, and then said anxiously to Wu Hao.
"Haha, I just want to go there and see it with my own eyes. You are busy with your business, don't worry about us, we will take care of ourselves." Wu Hao replied with a smile, and then glanced at the other side who had finished vomiting and was drinking water.
Zhang Jun.
"Coming down, coming down." Someone shouted at this time.
And this shout focused everyone's attention on the increasingly larger rockets and parachutes above their heads.
Zhang Jun, who looked pale, also walked to Wu Hao at this moment, and then looked at the rocket above his head seriously.
They saw the rocket slowly falling under their gaze, and everyone's hearts were in their throats.
The rocket engine ignition and reverse thrust before landing is crucial. If it fails, even with a parachute, the rocket will crash due to too high speed.
According to the design requirements, after the main parachute is opened, the rocket will fall at a speed of 9 meters per second. Although this speed is much slower than free fall, it is still very fast.
Although it is still possible to further increase the area of the parachute to further reduce the landing speed, this will also cause some other problems.
First of all, the increase in the parachute area means that its folded volume will increase and its weight will also increase. This also means that the rocket will bear more additional weight, thereby increasing the launch cost.
Second, the larger the area of the parachute, the larger the wind surface, and the greater the impact of airflow. As a result, the rocket is more sensitive to the impact of airflow when landing. If the wind speed is slightly higher, the rocket may be carried by the parachute.
Blow off. This will affect the landing accuracy and may even lead to recovery failure and other problems.
Therefore, the size of the parachute and the weight of the rocket must be controlled at a relatively balanced point, and the landing cannot be too fast or too slow.
For this reason, scientists have installed a rocket reverse thrust device at the tail of this type of return spacecraft. In order to start the rocket to boost and decelerate the moment before the spacecraft lands, so that the spacecraft can reach a tolerable level when it lands.
The lower speed protects the spacecraft from falling to the ground due to excessive speed.
Take the first-stage body of the return-type rocket they tested this time as an example. It will ignite the engine instantly about ten meters above the ground, and make the engine's thrust reach the maximum in an instant.
However, the ones next to the original engines are definitely not enough. The design team also has three small solid fuel rockets on the three sets of landing gear of the rocket to provide additional thrust.
The height of ten meters is still very high for us people, but it is also the height of the rocket itself. Moreover, the rocket's descending speed is nine meters per second, which means that the rocket only has one second of reaction time.
At this second, the rocket engine must be fully ignited. This will not only have very strict requirements on the rocket body control system, but also on the reliability of the rocket.
Either all ignition is successful and the rocket lands safely, or ignition fails and the rocket lands and crashes.
Just as Wu Hao was in a trance, a huge parachute appeared in front of him, and the rocket under the parachute descended rapidly under the gaze of everyone.
Then when it was about to touch the ground, the tail engine suddenly ignited and erupted a huge flame, and this flame also rolled up a huge cloud of sand and dust on the ground mixed with the smoke generated by combustion, which instantly enveloped the rocket.