Military Technology

The latest website: Under the gaze of everyone, the rocket draws a white smoke line in the blue sky. With the breeze blowing, the smoke line began to gradually dissipate.

As for the rocket, it flew higher and higher, and in the end there was only a twinkling bright spot left. If it wasn't for the clear and clear sky, it would have disappeared from everyone's sight long ago.

"21070 meters, the rocket started to descend!"

"The optical tracking observation team reported that the heat shield on the top of the rocket has been separated and the guide chute has been ejected."

"Pay close attention to the landing attitude of the rocket!"

"The grid panel is open, and the posture is normal!"

"21000, 20000, 19000..."

As the broadcast numbers gradually decreased, everyone clearly saw the whereabouts of the rocket again. The positive rocket was like a daytime meteor, dragging a faintly visible wake and falling to the ground.

"16000, the main parachute is thrown!"

"The optical tracking observation team reported that all three main umbrellas are open and in normal condition."

Clap, clap... Everyone in the control center and outside watching this scene applauded enthusiastically. As long as the main parachute is opened, it means that more than half of the entire return experiment has been successful, and the next part is waiting for the rocket to land.

Wu Hao and the others could also see through the naked eye that the rocket began to descend slowly, dragging three huge red and white parachutes. At this moment, the people in the control center also ran out, and everyone looked up at the sky, watching the slowly descending figure of the rocket.

"Affected by the increase in high-altitude wind speed, the rocket began to deviate to the northwest."

"How much is the offset?"

"It is estimated to be about one kilometer."

"Continue to observe closely, notify the ground recovery team, and prepare to go to the relevant area to prepare for the rocket's whereabouts."

Hearing this order, Wu Hao waved his hands and said, "Let's go, let's also go to the scene to have a look."

Zhang Jun nodded, and then boarded an off-road vehicle with Wu Hao and flew towards the crash site of the rocket.

And behind their car,

Many other vehicles followed. Sitting in the car, Yu Chengwu urged the driver to hurry up, while holding the walkie-talkie and said: "Anything can happen when the rocket lands, and there is still a lot of fuel left inside the rocket. Yes. So inform everyone to keep a safe landing distance to avoid possible dangers.

When it landed safely, immediately set up a quarantine line, except for professionals, other people are prohibited from approaching. Especially Mr. Wu and Mr. Zhang, hold him, protect their safety, and don't let them approach. "

After saying this, Yu Chengwu yelled at the driver in front: "Hurry up!"

To be honest, Wu Hao and the others didn't feel well in the car. While leaning against the window to watch the rocket falling in the sky, they had to endure the bumps of the car driving on the sand dunes.

This guy Zhang Jun couldn't bear it after a few bumps, his face turned pale, and he was trying to hold back.

Fortunately, this time did not last long, and the vehicle stopped on the top of a higher sand dune. Many vehicles have been parked on this sand dune, and these are the personnel of the ground recovery team.

At this moment, the rocket is already very close to the ground, and it is 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 continue to move forward. Who knows if there will be problems at a height of five or six hundred meters.

"Mr. Wu, why are you running so fast?" Yu Chengwu got out of the car out of breath, and said anxiously to Wu Hao.

"Hehe, I just want to go to the scene to see it with my own eyes. You are busy with your work, 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.

"It's coming down, it's coming down." Someone shouted at this time.

And with this shout, everyone's attention was focused on the rocket and parachute that were getting bigger and bigger above their heads.

The pale Zhang Jun also walked to Wu Hao's side at this moment, and then looked at the rocket above his head seriously.

I saw the rocket falling slowly under their watchful eyes, and everyone's hearts were raised to their throats.

The ignition of the rocket engine before landing is very important. If it fails, even with a parachute, the rocket will crash because of its excessive speed.

According to the design requirements, after the main parachute is opened, the rocket will descend 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 area of ​​the parachute increases, which means that its folded volume increases and its weight also increases. This also means that the rocket will bear more extra weight, which increases the cost of the launch.

Second, the larger the area of ​​the parachute, the larger the windward surface, and the greater the impact of the airflow. In this way, the rocket is more sensitive to the influence of airflow when it lands. If the wind speed is slightly higher, the rocket may be blown away by the parachute. This affects the landing accuracy, and may even lead to problems such as recovery failure.

Therefore, the size of the parachute and the weight of the rocket must be controlled at a relatively balanced point, and the landing can neither be too fast nor too slow.

For this reason, scientists have installed rocket thrust reversers at the tail of this type of returnable spacecraft. The purpose is to start the rocket to boost and decelerate the spacecraft at the moment before landing. This enables the spacecraft to reach a lower speed that can be tolerated when it lands, and protects the spacecraft from being damaged by falling to the ground due to excessive speed.

Take the first-stage rocket body of the returnable rocket they tested this time as an example. It will instantly ignite the engine about ten meters from the ground, and instantly make the thrust of the engine reach its maximum.

However, it is definitely not enough to be close to the original engines. The design team also has three small solid-fuel rockets on the rocket's three landing gears to provide additional thrust.

A height of ten meters is still very high for us, but it is also the height of the rocket itself. Moreover, the speed at which the rocket descends is nine meters per second, which means that the rocket has only one second of reaction time.

In this second, the rocket motor must be fully ignited. This will have very strict requirements not only for the rocket body control system, but also for the reliability of the rocket.

Either all ignitions are successful and the rocket lands safely, or the ignition fails and the rocket lands and crashes.

While 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 emitted a huge flame, and this flame also rolled up huge dust on the ground mixed with the smoke generated by the combustion, instantly covering the rocket.