Xiao Yizhan looked at the formulas copied by his grandson's handwriting on the piece of paper in his hand. Based on his years of academic experience, it is clear from the few customary letters in the formula that these formulas are used to calculate the lift of the airfoil and the force of the air flow on the wing of the aircraft. He knew that his grandson had gotten a photo of a foreigner flying in the air as an inflatable parachute some time ago, and he had the idea of making one himself. His grandson can be interested in aviation and has such ambitions, of course, he can't ask for it, so he also said a lot of words of encouragement to his grandson. This time, when his grandson came to read the NASA material for himself, it seemed that he had already begun to carry out his own "grandiose" plan, which of course made him happy. However, it is safe to say that these formulas copied by his grandson are absolutely not derived from any of the books or materials he has read, based on what he has seen from a wide range of books.

Xiao Lao is now a little worried, if his grandson relies on these formulas that are difficult to distinguish between truth and falsehood from nowhere, if he takes the wrong path from the beginning, and finally fails to successfully complete his own dream of making a self-made flying machine, will it hit his grandson's interest and confidence in aviation? If you let yourself have no heirs because of this, wouldn't you lose a lot of money?

However, Old Scholar Xiao did not alarm his grandson at the first time. He found one of these formulas, left the study and went to the living room, found a few pens, took out a pen, and began to find one of his most common examples to check this formula. In fact, he estimated that this formula should satisfy this example. Because with his skillful mathematical ability, he has concluded that this formula can actually approximate the deformation of a classical formula, but the deformation process may require a lot of assumptions and complex deductions. It's not an easy variant.

The results of the verification did not surprise Xiao Yizhan, and it confirmed that this formula could be used for that classic example. No problem. He also noticed that the error between this formula solution and the classical analytic solution was very small, 7 decimal places.

After getting this result, Xiao Yizhan was a little surprised. As an approximate solution, the formula solution relies on the empirical formula obtained from thousands of trials, and the error of the traditional empirical formula is mostly two or three decimal places, which is very happy. And now the formula I got in my hand turned out to be 7 decimal places away from the analytic solution, which can be regarded as quite accurate in the field of engineering.

Xiao Lao's heart moved. Hurriedly went to his bedroom, found a large paper bag, rummaged through it for a while, and found a thick notebook. He took the notebook to the living room, flipped through the data, and began to calculate it using the formula he had just made. These data were recorded six years ago when he was involved in an aircraft project and conducted wind tunnel tests at another base. Although the aircraft of that project had gone through a design process of nearly ten years, it was abandoned because of the unsatisfactory results of the wind test. Xiao Lao wants to use these measured data to verify this formula again, and then see the difference between this new formula and the traditional empirical formula. To know the road, in the design process of this model for nearly ten years. There is nothing wrong with the results calculated by the classical empirical formula, but still in the wind tunnel test at the end of the test, the test overturns the previous calculation results.

Due to the large amount of data, this time the old man Xiao took a bit long to calculate. But Xiao Lao still calculated meticulously. And with the increase in the amount of data calculated. Xiao Lao's mood experienced shock, excitement, and excitement. He found that the results of this formula were in striking agreement with the results of the wind tunnel tests. The agreement between the two data has reached more than 98%. The inconsistent data does not rule out that there was an error in the measurement at that time or that I made a mistake this time. This illustrates. This formula is perfectly usable and surprisingly accurate. This formula is a treasure! If only that model had been able to use this formula at the beginning. In this way, problems can be detected in time and changes can be made to the structure and layout. Then you won't fail in the wind tunnel and lose to another competitor, and maybe you can continue to develop now. Moreover, the accuracy of this formula is so high, which shows that in the design process of the model, if most of the structures are calculated based on this formula, then a lot of time can be saved for wind tunnel testing, and the advantages in cost and accuracy are self-evident. If the other formulas on that piece of paper were of the same degree of accuracy, it would be of great help to the new aircraft that are being studied in the factory right now!

Thinking of this, Xiao Lao couldn't sit still, he immediately got up and walked to the study, eager to check the situation of the other formulas. If the other formulas are the same as this formula, then you must ask your grandson about the origin of these formulas. This should be given in the book of a great bull. It's a shame that I've been doing research all my life, and I've never turned to that book, which is really a big loss. No, you must ask for the book from your grandson, and you must study it yourself. There must be a lot of useful knowledge points in it, which are worth studying and learning by yourself.

When Xiao Lao walked into the study, Luo Yu had just completed all the calculations of his wing airfoil. He rubbed his swollen eyes, stretched, and looked up just in time to see his grandfather walking in from outside. He said happily, "Grandpa, are you back?!" ”

Xiao Yizhan smiled and said to his grandson, "Yes, grandpa has been back for a while." What are we Xiaoyu doing? Grandpa is so fascinated by you there? ”

Luo Yu ran to his grandfather's side, he was already about the same height as his tall grandfather. He showed his grandfather the results of his calculations as if he were offering a treasure.

"Grandpa, look, this is all the data for an airfoil I just calculated, and it looks pretty good, right? I'm going to have to count ten more airfoils to decide which one is the best. ”

Xiao Yizhan looked at the airfoil shown to him by his grandson and asked, "Oh, did you choose a low-speed airfoil?" ”

Luo Yu said confidently: "Yes." Shen Yiyi said that the speed of our paramotor will probably not exceed 50km/h, so we should choose a wing shape with higher lift and less stress in the low-speed wing, and the structure should not be too complicated. Moreover, she was going to be fruitful in a week, so I had to do the math in the low-speed airfoil. ”

It seemed that it was very difficult for him to say it, but judging from the fact that he was so dedicated, he was actually very confident in this matter.

Shen Yiyi? I remember this seems to be a girl I met when my grandson went to the city to attend a lecture last time, right? And it seems to be a special girl who studies physics. Could it be that this time her grandson is actually working with her on the production of flying machines? Xiao Yizhan pretended not to care and asked his grandson: "Who is Shen Yiyi?" Why do you think that doing paramotor has something to do with her? ”

Luo Yu suddenly remembered that his grandfather knew that Shen Yiyi was a female classmate. At his own age, parents are most afraid of their children's early love. mentioned her all of a sudden, if her grandfather misunderstood her early love, it would not be good. He hurriedly added: "Shen Yiyi is a female classmate in the physics competition class of the city's No. 11 Middle School. This time, our competition class of Shen Fei No. 1 Middle School and the No. 11 Middle School of the city formed a group to study paramotor, with Shen Yiyi and I as the team leaders. So we have our own division of labor. For example, Fang Bing and a classmate from No. 11 Middle School were responsible for calculating, and Li Xiang and a classmate from No. 11 Middle School were responsible for finding that ...... Supplier, I am responsible for the collection of information, and then Shen Yiyi is responsible for the production of the power part and the entire umbrella. ”

Xiao Yizhan saw his grandson introduce the situation of his group in such detail, and thought to himself, it turned out to be a group activity, so he was not afraid that the two young people would cause trouble together, but he didn't know that Shen Yiyi would also be in charge of the power part. But I don't care about that for now, I still have a more critical question that I haven't asked. If you don't ask this question clearly, you won't want to fall asleep tonight.

"By the way, Xiaoyu, where did your calculation formulas come from? Don't make a mistake, the design will be wrong, and the aircraft that comes out of the last will not be able to fly. ”

Luo Yu heard his grandfather say this, scratched his head, and said, "This is also possible." But probably not. When Shen Yiyi wrote these formulas to us, I saw that she was still very careful. I also checked it when I copied it. So there shouldn't be anything wrong with that. Shen Yiyi said that the accuracy of these formulas is still very high, and under the current ability of electronic computers, the accuracy of these formulas will exceed the accuracy of machine calculations, so there is no problem in applying them in the low-speed area. ”

Xiao Yizhan was surprised, he didn't expect that the source of this formula that surprised him was not from which book his grandson saw, but from that female classmate. And it seems that the female classmate is also very confident in the correctness of these formulas. I heard my grandson say that the classmate gave the formula and the application interval and accuracy of the formula, and even said that it would exceed the accuracy of the current computer, which shows that the classmate's understanding of the formula has made a lot of effort. Could it be that she got a monograph on aeromechanics somewhere, and she never saw it?

"Xiaoyu, this classmate Shen Yiyi, what is she doing at home? Does she have any elders who are also involved in airplanes? Or did she tell you where she got the formulas from? (To be continued......)

PS: I was sprayed in the book review area this morning, and I was very hurt to write a novel is originally an old bottle of new wine, and the plots in all the novels we write now have actually been written before. However, restoring these plots in one's own language is what a new novel wants to bring readers to the viewing experience, and the plot development in a novel is actually just a logical arrangement and combination of various events. Just because of the similarity of a plot and say that others are thick-skinned, or even insinuate plagiarism, it is a kind of harm to any author, complain with free paragraphs behind this chapter, and you can only use the clear person to clear yourself to comfort yourself after the most, this book is about to be recommended, and everyone who has not collected it is still a strong collection. It's not going to be easy to find this book from next week. I hope to subscribe and vote enthusiastically. The author relied on this thing to cheer him up.