Courtyard House: Starting with a 28-inch motorcycle

Just as it reached maximum speed, the front wheel lifted off the ground—the fuselage leaped lightly and rose steadily!

Five meters, eight meters, ten meters... It really was suspended in mid-air!

Xiao Yao lightly pushed the joystick with his wrist, and the plane tilted to the side, then rolled, circled, dived, and climbed, the movements so crisp they didn't seem like they were made by hand.

"It's done! We really flew!" The three of them suddenly hugged each other and jumped high into the air.

Ji Fengnan looked up, her eyes shining, not with tears, but with light.

Xiao Yao felt a burning sensation in his chest and a tingling sensation in his fingertips—the formulas on paper had finally grown wings; the laws of mechanics in the textbook were now carrying steel, drawing arcs in the real sky.

The plane slowly landed on the concrete ground, and the four people rushed towards it, colliding violently with each other.

"Xiao Yao! You're amazing! Your approach is brilliant!" Wang Yutong shouted until her voice was hoarse.

"Let me try!" Qian Wentao snatched the remote control, his fingers already itching to play.

Xiao Yao lay back on the grass, gazing at the gradually blue sky, and softly asked the system, "Did you see that? It's flying."

"Tsk, just a toy. Compared to the real thing, it's not even a lighter," the system replied coldly.

"That's normal. If we work harder, we'll definitely catch up." Xiao Yao said in a light tone, his eyebrows slightly raised, showing no sign of dejection.

The system snorted coldly, too lazy to reply.

Ten minutes later, the plane suddenly lost power and, as if its bones had been removed, slid softly toward the ground.

Qian Wentao slapped his thigh: "The battery is almost empty! It's already a good thing we've handled it well and adjusted the circuit accurately if it can last for half an hour."

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On the way back, all four faces glowed with a bright red light, and their eyes were as bright as freshly wiped glass.

They wrapped the airplane tightly in three layers of cardboard, then padded it with an old sweater, and held it in their arms like they were protecting a newborn kitten. If a passerby glanced at it, Qian Wentao would immediately tense up, his eyes scanning the area like a wary squirrel with its ears perked up.

Fortunately, they weren't the only ones returning to their dorms—students from other groups were also sneaking around carrying their artwork, some stuffing it into backpacks, some wrapping it in old painting tubes, and others simply holding their school uniform jackets in front of their chests, glancing down as they walked. Everyone understood without saying a word, and no one asked any further questions.

The next day, just as the class bell rang, Director Gao pushed open the door and walked in, his voice clear and bright: "Register your numbers and head out immediately to the Peking University lab for a live demonstration! The professors will provide on-the-spot feedback, scoring you based on creativity, completion, and the rationality of the underlying principles."

Now, all the groups clenched their fists, and the air was filled with the aroma of something eagerly roasting.

As soon as the notice was issued, everyone rushed to the dormitory, wrapped their precious treasures in bubble wrap, stuffed them into insulated bags, and put them in canvas bags, then jogged to catch the bus with Director Gao.

Xiao Yao and his friends' cardboard airplanes were lightweight and easy to carry, fitting comfortably in a shoebox. Everyone on the bus had a bag slung across their shoulder, exchanging furtive glances—not of rivalry, but more like the knowing, tentative understanding between old friends meeting. Who made what? I really wanted to take a look.

……

As soon as the shuttle bus came to a stop at the west gate of Peking University, groups from various schools began to gather: students from Huazhong University of Science and Technology carried metal frames, Nanjing University towed voice-controlled boats, and even a few high school students from the neighboring affiliated high school wobbled into the school gate carrying glowing sand tables. Several professors from Peking University stood on the steps to greet them, leading everyone through the ginkgo-lined path and straight to the lecture hall on the third floor of the physics building.

Not only did the school's own teachers come, but also two elderly professors with neatly combed white hair—one from the Institute of High Energy Physics of the Chinese Academy of Sciences, and the other who spends most of his time in the aerospace materials laboratory and rarely makes an appearance.

The purpose of this competition was not to select "child prodigies," but to let the children bring the formulas to life with their own hands, making electricity, gears, and levers come alive at their fingertips.

These kids are smart, but they've only been studying physics for a few months and can't even name an oscilloscope properly. The professors don't expect anyone to create any groundbreaking technology; they just pat them on the shoulder, nod, and say, "That's an interesting idea."

As soon as the professors entered, the entire room fell silent for a moment. Some people unconsciously straightened their backs, while others repeatedly fiddled with the edges of their bag straps, their fingertips slightly damp.

This was the first time that Newton's laws, Ohm's theorem, and the conservation of energy from textbooks had truly become small, buzzing objects in my hands. No one was afraid of losing; what was scary was that something they had painstakingly built could be easily exposed with a single, casual remark, causing the teacher who had spent countless nights helping them modify circuits to sigh softly.

Director Gao handed the registration forms to the Peking University professors, who then assigned numbers according to the sign-in order. Xiao Yao and his group of four were at the end of the line, twelfth in line.

Qian Wentao slumped his shoulders: "I should have known Ji Fengnan wouldn't have gone to the toilet! All her bad luck has clinged to us! Even if we don't get first place, we should at least get second, right?"

Wang Yutong laughed and shoved him lightly: "They didn't throw a toilet at you—besides, wouldn't it be better to go on stage later? You can learn from them first and see how they turn wild ideas into reality."

Qian Wentao sighed and waved his hand: "Alright, alright, it's the grand finale then. I can open my eyes wide and learn something."

Ji Fengnan quickly scratched the back of her head, her ears burning: "My bad, my bad... Come on, look at that group in front, they've already opened half of the boxes!"

At this moment, Professor Chen strolled over, winked at them, raised his hand and made a "slow and steady wins the race" gesture, then turned around, stepped onto the podium, and sat down in the circle of professors.

Xiao Yao looked at the three chattering people in front of him and couldn't help but smile. They seemed undisciplined, but once they focused on something, they were like tightly wound springs, turning faster and faster, and turning more and more evenly.

On stage, the host had already rang the opening bell.

The first group pushed up a four-wheeled cart with a smooth, wood grain finish, powered solely by a spring. Fully wound up, with a click, the cart steadily traveled nearly eight meters, its body without a trace of glue, the axles meshing so tightly that no extraneous noise could be heard. All the participants were girls, their fingers still bearing sawdust and faint traces of gentian violet. The surrounding students spontaneously applauded.

The second group brought out a model of a lifting platform: the aluminum frame was slender, the motor hummed softly, and when the tray was halfway up, it wobbled slightly but hovered steadily for three seconds. The professors nodded: "Simple structure, ingenious control." The group members jumped off the platform, raising their arms high, as if they had won a basketball game.

The third one brought onto the stage initially appeared to be a tin man with distinct joints—but upon closer inspection, it became clear that it was merely an alloy skeleton welded with copper wire. When powered on, a motor would pull the linkages, mechanically taking two steps and raising an arm once. There was no voice, no response, and even steering had to be done manually.

Xiao Yao stared at the brass gear at its knee and nodded silently to himself: Ideas are more valuable than parts.

As soon as the first few groups appeared, many students in the back row quietly tightened their backpack straps. But no one backed down—even a thermos that changes color or a paper windmill that can measure wind speed was carefully carried onto the stage, earning the professor's comments such as "the materials were used very cleverly" and "the data recording was very meticulous."

Finally, it was the turn of Xiao Yao's class's undisputed "ace team"—the five-person team led by Lin Siyue and Xu Wenxin. Their grades ranged from the top three to the seventh in the grade, and they were privately known as the "Five Tigers Team." As soon as the box was opened, the entire aisle was instantly filled with heads, and even students from the neighboring high school craned their necks to see inside.

As they gently pushed a small boat into the display pool in the center of the venue, Lin Siyue pressed a switch, and the motor immediately emitted a crisp, clear "tap-tap-tap" sound, as powerful as a heartbeat. Xu Wenxin moved his finger slightly, and the remote control turned gently, and the small boat moved forward as if it were alive, nimbly swaying its tail, turning around on the spot, and even drawing smooth arcs around the buoy.

What's even more impressive is that a miniature generator is embedded in the cabin. As the ship moves forward through the waves, the propeller drives the impeller in the opposite direction, converting kinetic energy into electrical energy, which is then fed back into the battery without any loss.

The professors immediately gathered around, seven or eight pairs of eyes fixed on the small boat. Some bent down to examine the transmission structure closely, some reached out and lightly touched the motor casing, and others squatted down to pry open the hatch and examine it repeatedly. They were all calculating in their minds: if this design were scaled up tenfold or a hundredfold and installed on a cargo ship deck, how much fuel could be saved? And how much emissions would be reduced?

Xiao Yao quietly exhaled, his heart trembling slightly—the idea of ​​"generating electricity during navigation" alone surpassed the plan he had spent half a semester finalizing. These people had never even disassembled a pulley system before entering school, and had only taken one full semester of physics classes, yet they were able to thoroughly understand the principles, swallow them, and then spit out new insights.

Unlike their successors who had readily available materials and standard answers, this group of students today did not rely on any shortcuts. They transformed blueprints into real, reliable tools by trial and error, through trial and error and revision.

Finally, it was Xiao Yao's group's turn to take the stage. Director Gao's face lit up, his smile reaching his eyes: "Come on, tell us what you've come up with?"

The Lin Siyue group, which had just been praised by all the professors, was his student group, so he was naturally overjoyed.

Qian Wentao straightened his back and answered loudly, "Airplane."

Ji Fengnan lifted the lid of the cardboard box and held out a half-foot-long cardboard airplane with both hands—the fuselage was made of aluminum foil, gleaming with a cold silver light; a full five-pointed star was drawn on the belly of the plane with red pen, its edges sharp and full of spirit.

The classmates then realized: they really weren't bragging back then! They really did make an airplane—as for whether it could actually fly? Nobody knew for sure.

Director Gao frowned slightly: "Is this... a static model, or... something that can actually move?"

Before the words were even finished, the entire room fell silent for a moment. The professors exchanged bewildered glances, and the students watching craned their necks to peer inside—this thing looked heavy, not like a piece of paper. Could it have been thrown from the second-floor balcony?

Wang Yutong stepped forward, her voice soft but clear: "It can fly."

A murmur of surprise and disbelief suddenly arose from the crowd.

Upon seeing this, Qian Wentao raised his chin and suddenly raised his voice: "It really can fly!"

……

The professors, though slightly taken aback, quickly nodded in agreement: "Then please demonstrate." An elderly professor with white hair gestured.

Qian Wentao felt a surge of determination—those doubtful looks from before felt like thorns in his back. He declared loudly, "This room is too low; there's not enough room to turn around. If we want to fly, we need to go outside to a bright, open place!"