The military-industrial scientific research system of the academic master.

Chapter 1210 High Altitude Test

Yungang.

101 high-altitude simulation test area.

Several Coaster minibuses equipped with dark side window glass drove one after another on the winding mountain road and finally stopped in a parking lot halfway up the mountain.

Rocket engine testing must, of course, be conducted away from densely populated areas.

Combined with a series of requirements such as confidentiality, noise reduction, and energy supply, mountainous locations will be chosen in most cases.

Therefore, as soon as Chang Haonan got off the car, without even having to enter the control center, he could see from afar two white, blue-roofed buildings suspended in the air, about a few kilometers apart.

Compared with the large ground thrust test benches seen on the road, these two buildings are obviously smaller in scale.

But it still has all the organs.

There are also some inconspicuous auxiliary equipment distributed nearby.

Near one of the test benches, several chimney-like objects were emitting faint white smoke, obviously making final preparations before the test run.

"Academician Chang, this is the GS-2 high-altitude simulation test bench that we built at the end of last year. It is planned to be used for testing the second and third stages of the new generation of launch vehicles... However, apart from the acceptance test, this is actually the first time it has been put into formal use..."

The deputy director of the Yungang Experimental Zone who was in charge of the reception was Wang Zhiwu, who also graduated from Beijing University of Aeronautics and Astronautics.

At this moment, he was following Chang Haonan, walking towards the control center not far away, while introducing the basic situation of the test run:

"GS-2 uses the same engine-supersonic diffuser-steam ejector combination as GS-1, but it can withstand greater thrust and fuel pressure. It can simulate high-altitude environments up to 60km and conduct cold and hot tests of the entire system..."

In order to reduce the difficulty of designing the power system, the hypersonic verification missile was air-launched at the beginning of its planning. The engine will work at an altitude of more than 15km almost throughout the entire process, so the testing process is also similar to that of the second-stage engine of a general launch vehicle.

"Due to cost and construction period issues, only eight YF76s were available for testing. Although the overall reliability index in the design requirements was not high, considering that the engine from the whole machine to the components is basically a "single point failure", we still adopted the marginal operating condition test method inherited from the 8-921 project. The single test time is 4 seconds, the cumulative time is not less than 600 seconds, and the thrust variation range is 57600%-86% of the rated thrust..."

"..."

YF76 is the name given to this engine by the Sixth Academy.

The core first-stage and core second-stage engines currently being developed for the new generation of heavy-lift launch vehicles are called YF77 and YF75D respectively.

Although the thrust of the engine used in the hypersonic verification missile is much smaller than the above two, it actually uses many of the same technologies.

So we gave it a name that was somewhere in between the two.

As they were talking, the group had already walked into a nondescript building nearby.

Since rocket engine testing is much noisier than jet engine testing and also involves extremely dangerous propellant components such as liquid oxygen and liquid hydrogen, the control hall and test bench are generally not placed together.

At this time, the commander-in-chief of the entire test work and also a key figure in the Yungang Test Area, Zheng Bin, was sitting behind the command desk, waiting for the final moment to issue the engine ignition command.

Seeing Chang Haonan and others come in, he immediately stood up:

"Report to the person in charge, the YF76 engine test run is ready, all indicators are confirmed to be normal, and the test can be started at any time!"

Chang Haonan is the overall person in charge of the entire hypersonic weapons research and development mission, but he does not directly manage the work of the 101 Institute. He is a county official, not an active manager.

So he did not answer directly, but looked at Chen Zhiwei, who was half a body length behind him.

"Director Chen, we are just conducting an on-site observation. Please continue according to the scheduled schedule."

"Yes!"

Duan Zhengbin gave a crisp answer and then sat back at his command station.

The engine test bench is equivalent to a launch tower that cannot be launched.

The configuration of the test command hall is almost identical to that of the control hall of the satellite launch center.

In the upper right corner of the large screen in the front, a countdown is displayed with less than 10 minutes left.

That was when the test was scheduled to begin.

……

Just like the situation before the rocket launch, the entire command hall was filled with a tense and silent atmosphere.

Or, rather, more than a formal rocket launch.

After all, most of the rockets ignited here are immature models that are still in the development process, and the probability of failure is much higher than in formal launches.

All that could be heard was an occasional command or two and the hurried footsteps of some technicians.

Finally, the time displayed in the upper right corner of the screen reached the countdown of 10 seconds.

Duan Zhengbin took a deep breath, pushed open the cover on the surface of the ignition button with his thumb, and moved closer to the microphone in front of him.

Before counting down the last five seconds, he used the corner of his eye to confirm the working conditions of the liquid hydrogen and liquid oxygen subsystems.

There are 22 sensor parameters on the screen, all displayed in green.

everything is normal.

The steady and clear voice sounded like a bell, ringing in the ears of everyone present:

"5...4...3..."

"..."

"ignition!"

At the moment the sound fell, a bright flame flashed at the engine nozzle under the test bench.

The high-temperature airflow generated by the combustion of hydrogen and oxygen gushes out of the thrust chamber at a speed more than 15 times the speed of sound in less than one tenth of a second, and pours out of the test bench along the steel plate at the bottom of the guide groove.

The dazzling light almost illuminated half of the hillside next to the test platform.

At the same time, the water jacket under the test bench was opened to start cooling the load-bearing corbels and cement base.

Where water and fire met, a white cloud that covered the sky and the sun immediately formed.

On the big screen, the camera lens closest to the test bench was even shaking slightly.

A few seconds later, a roar that was slightly behind the visual effects reached everyone's ears.

Although the distance was far, and the sound waves had been significantly weakened by the rocks and trees, one could still feel the huge thrust that the test bench was bearing at this moment...

Compared with Chang Haonan, the staff at the test center were already accustomed to such scenes.

Among rocket engines, the YF76 is not even considered to have a relatively high thrust.

Soon, the first report sounded from the loudspeaker:

"The engine operating parameters have reached the initial operating conditions!"

The initial point is the rated operating condition where the engine thrust and mixture ratio are at the design values. The engine operating conditions are relatively the best, and it is also the starting point of almost all test processes.

However, the marginal operating condition test method adopted by YF76 is to take into account the extreme operating conditions of the engine.

Therefore, the successful ignition can only be regarded as the first step in a long journey.

Duan Zhengbin felt relieved and gave new follow-up instructions:

"Adjust the operating parameters to A1 condition."

As soon as he finished speaking, Chen Zhiwei leaned close to Chang Haonan's ear and explained:

"The A1 operating point is low thrust and low mixture ratio. The operating parameters are significantly lower than the rated operating conditions. The turbine speed is reduced, and the pump outlet pressure is also reduced accordingly. However, the pressure required by the thrust chamber does not change much, so the vibration environment is relatively harsh, which is a big test for the main structure of the engine..."

As if to verify this statement, the vibration acceleration curve displayed on the large screen began to fluctuate violently, causing dozens of other key parameters to change as well.

Fortunately, the control feedback system started to work almost immediately, keeping the operating parameters of each system within an acceptable safety range.

Chen Zhiwei continued:

"We took into account that the vibrations and initial ignition posture of the rocket in the case of air launch are much worse than those of ground launch, so we left a lot of redundancy at the beginning of the design to ensure the highest reliability of ignition and the initial 10-second attitude adjustment stage..."

"..."

Looking at the test time that kept jumping on the screen, Chang Haonan also breathed a sigh of relief:

"The bomb bay of our air-launched vehicle was not designed with this kind of mission in mind, so it needs to be modified specifically."

"If there are no problems with today's preliminary test data, we can send the basic parameters of the thrusters to Gaofei Group..."