On the test bench of the workshop, the staff who had already received the order from the leader of the institute installed a change engine waiting for the test run. The machine is not very large, and is only slightly larger than the size of a travel bag. From the perspective of the veteran employees of the 606 Institute, this engine can be said to be the smallest engine processed and manufactured by the institute itself.

Of course, this is also easy to understand. After all, this is a power source that needs to be attached to a paramotor that is carried by a single person, so it must first be able to be carried by one person in terms of weight. If it's too heavy, it's another matter whether it can fly or not, just considering that a person has to carry a hundred pounds of iron lumps on the road, you can see what a failed design it will be. Therefore, when Shen Yiyi was drawing, he had clearly specified that the materials used must be lightweight materials. Of course, in this era, the so-called lightweight material cannot be the carbon fiber material that was very popular in later generations, but only a heat-resistant aluminum alloy material. Speaking of this, I have to sigh at the good life of Shen Yiyi. For example, the largest user of aluminum alloy materials in China is AVIC, because these are controlled materials. If it weren't for the help of the old man Xiao Yizhan and the relationship between the old man An Zhusheng, with a nameless junior like Shen Yiyi, who is not famous in the aviation industry, it would be tantamount to a fool's dream to be able to use this kind of control materials for his own design.

Of course, even if lightweight materials are used, for the purpose of controlling the total weight, of course, the size of the engine itself cannot be too large, so the total volume is only larger than a travel bag. Fortunately, the flight speed of the paramotor is not large, so the power drop caused by the shrinkage of the engine volume will not have a big impact on the flight performance of the future product umbrella. In addition, the wing shape of the umbrella has also been optimized by Shen Yiyi's friends after repeated calculations, and it has become possible to achieve better climbing performance with less engine power.

Mr. Xiao Yizhan is the first time to see the engine entity with his own eyes after the engine was really built. The first time he saw it, his eyes lit up. I saw that the prototype in front of me was completely different from the dirty or red-painted prototype in my impression, although the prototype in front of me was small, but it was shining with a silver-white metallic luster. The parts of the casting seem to have undergone a matte finish. However, the surface of some of the processed body is very delicate. Old man Xiao Yizhan couldn't help but praise Old man An Zhusheng and said: "Old Antou, I didn't expect that the processing level of the factory you affiliated with is really different from before." The machine is placed on a bench and looks like an exhibit. I didn't expect this prototype engine first piece to look so good. ”

Mr. An Zhusheng himself actually saw the entity for the first time after the assembly was completed. To be honest, he himself was a little amazed by the machine. However, he was never willing to be left behind, and he only replied proudly and awkwardly to Old Man Xiao's praise: "Of course." But Lao Xiao, you're not Lao Hutu, right? This is a magnesium aluminum alloy material, and the effect of natural processing of this material is different from before. Therefore, our processing technology is naturally improving, but the shape processing effect you are talking about is largely due to the difference in product materials. ”

Of course, the comings and goings of the two old experts did not affect the tense preparation of the staff in the test workshop for the upcoming test. The test workers in blue overalls are installing some sensors or other onto the engine prototype, and some of the instruments used for measurement are also being connected according to the test procedures. On the other side, the staff in white coats are turning on the test system here. They are all veterans with a long history of testing, but the engine testing here today is still a novelty for many of them – many years ago. The 606 Institute is the first time to test such a compact piston engine.

After receiving the staff's signal, Deputy Chief Engineer Zhou, who had been accompanying the two old experts, ran to the ear of Mr. An Zhusheng and whispered a few words to him. An Zhusheng looked up at Xiao Yizhan and asked, "Old Xiaotou, now that the sensors are installed, and some oil and water pipelines are also connected, they say that the car can be moved now." What about your opinion? Let's start testing now? ”

Old man Xiao Yizhan was a little excited, and he even felt his hands tremble slightly. Of course, he had already learned about it from An Zhusheng. The engine in front of me may have an air leak, but somehow. He always had a hunch that this engine might give everyone present a big surprise, not a disappointment. He felt that he might witness another miracle created by Shen Yiyi, a young genius student.

Therefore, for An Zhusheng's question, after taking a deep breath, Old Man Xiao said very firmly: "Let's start the test." ”

With An Zhusheng, the old man nodded. Deputy Chief Engineer Zhou gave the order to test the car, and a middle-aged engineer in a coat next to the test console pressed the button of the test run. I saw that the various indicators on the control board began to jump.

As soon as the engine started, Mr. An Zhusheng let out a "huh". The sound of this machine is noticeably quite quiet. Not at all, of course, but the noise of this machine is noticeably different compared to other engines they have touched with the same stroke and similar displacement. Old man An Zhusheng couldn't help but ask Deputy Chief Engineer Zhou: "Xiao Zhou, is this engine running?" ”

Vice President Zhou himself is also unsure. He also felt that the starting sound of the machine was too quiet. It was so small that the action of preparing to wear the earbuds that he had expected before seemed redundant. He looked at the others in charge of monitoring the engine's metrics and received an affirmative answer from them.

"Yes, Mr. An, the engine has started."

Hearing Vice President Zhou's answer, An Zhusheng said "um". He thought in his heart that the sound was so small, if the workshop was more noisy, the sound of the engine would be completely covered. In this way, if you run into a silencer, then this engine can be regarded as a silent engine. With this feature, even if it is a slight air leak, this engine can be regarded as characteristic and worthy of further study.

An Zhusheng motioned to Deputy Chief Engineer Zhou to continue to speed up and see the engine performance when it reached the rated working condition. With the order given by Deputy Chief Engineer Zhou, the master worker who controlled the machine began to mix oil. Mr. An Zhusheng paid attention to the noise changes of the engine during this process, and did not seem to hear any major sound changes. Old Man An nodded secretly in his heart, which means that the engine runs very smoothly, so that the sound pressure level of the noise will be basically unchanged in the process of increasing speed.

Suddenly, there was a person in the control room who made a "huh", which attracted everyone's attention. Old man Xiao Yizhan, who had been following An Zhusheng, walked up to the engineer as soon as possible and asked him, "What's wrong?" What happened? ”

The engineer raised his head and saw Old Man Xiao's eager look, and then looked at Old Man An and Deputy Chief Engineer Zhou who walked behind Old Man Xiao, the two of them also looked suspicious, and couldn't help but hesitate and said, "That...... The engine has reached design power. ”

This surprised several experts, as did the other engineers who accompanied them. Several anxious people had already rushed to the monitor in front of him, and looked at the rising numbers on it, and let out the same cry of surprise.

Deputy Chief Engineer Zhou said to An Zhusheng with some embarrassment: "Teacher, I'm sorry, I think maybe the power meter is broken." I was not good at it, and I forgot to ask them to calibrate the meter before the test began. ”

An Zhusheng waved his hand: "This is not in a hurry, Xiao Zhou." Don't jump to conclusions just yet. Let's do the test first. After completing the test project, you can check it again to see if there is any problem with the instrument. Now the test is still recorded as usual. Let's go ahead with our previous test plan. ”

After giving instructions to the other test personnel of the 606 Institute to continue the test, Old Man An Zhusheng looked at Old Man Xiao Yizhan and said, "Old Xiao, I think maybe this little girl Shen Yiyi will give us a big surprise this time." If we don't have a problem with the power meter, then it's better that her engine is thermally efficient than any engine we've ever touched before. I had suspected that her engine was going to leak, but now it seems that I may have been mistaken. An Zhusheng no longer had the usual joking style when he spoke to Xiao Yizhan before, but this passage was very serious.

Xiao Yizhan saw that his old friend looked very serious this time, so he replied seriously: "Then you have to be careful." If there is no air leakage, it means that the current cylinder temperature and cylinder pressure have reached a relatively high level. I suggest that you keep the test data, and pay attention to the heat load of the body, so as not to burst the cylinder. ”

Old Man An Zhusheng nodded, and issued instructions one by one according to Old Man Xiao's suggestion. At the same time, he added a request. He asked everyone to write down as much data as possible, and at the same time, when issuing the report, in addition to calculating the actual efficiency of the engine, pay attention to the ratio of this engine to the Otto cycle and the Carnot cycle in numbers. The Carnot cycle is the theoretically highest efficiency achievable in a heat engine, while the Otto cycle is an ideal description of the thermodynamic process of a gasoline engine. The old man wanted to see how much the mechanical efficiency of Shen Yiyi's engine could reach.

And as the test progressed, the old man Xiao Yizhan was in a better and better mood. It was as if he had seen the scene of how much the genius girl of the mechanical discipline he had dug up could make to the aviation industry of the Republic in the future. And this feeling of having a successor made the old expert feel as sweet as eating honey. (To be continued......)

PS: The paramotor is coming out soon.

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