The Simulation Codes Hidden in Toys

When I was a child, all my belongings were in that old wooden box. Looking back now, that was my first laboratory. Inside it lay a car made of tinplate; when I spun its wheels with my fingertip, the gears inside would let out a creaking sound that felt oddly solid and comforting. Pushing it down a slope, it would run very fast, yet remain steady and never tip over. There was also that plastic airplane, its wing edges polished shiny by the friction of my palms. It couldn’t fly; I could only push it forward along the ground. But during those tens of centimeters of “runway,” staring at the wind beneath its wings, I felt it was no different from the real aircraft I saw streaking across the sky on television.

At that time, I was indeed only focused on playing. But after playing for a long time, a nagging question always lingered in my mind: How is it that when these gears lock together, the wheels spin so joyfully? And why does that airplane look exactly like the ones on TV, yet it simply cannot fly? Every day, as I tinkered with them, I was actually wrestling with these invisible, intangible principles. Later, I came to think that it was perhaps this obsession to “see through” my toys that, like a guiding thread, led me all the way from that old wooden box to Beihang University.

Later, when I first walked into the Air & Space Museum, and saw the J-10 standing there, its fuselage lines as sharp as a knife, I stared at it and thought to myself: This thing really looks just like that toy airplane from my childhood.

Unfortunately, I ultimately did not get into the aircraft design major as I had wished, but instead entered a broader field—the research and development of complex products. At first, I felt a bit disappointed, but it was precisely after starting research work in this direction that I suddenly came to understand: those childhood toys were never just pastimes meant to amuse children.

In equipment research and development, there is a term called the “prototype stage”. Before engineers build a large aircraft, they do not start directly; they first create a simplified model to see if the structure is correct and whether the approach is feasible.

To put it bluntly, developing real equipment is about making “toys” increasingly real and increasingly complex. Nowadays, engineers first conduct virtual simulations on computers, modeling how the wind blows and how fast the speed is. But this is not enough; physical verification is also required. For example, in the case of the “Tianmushan 10” supersonic passenger aircraft, a collaboration between Beihang’s Tianmushan Laboratory and COMAC, before it truly soared into the sky, the team first built a 1:18 scale demonstrator, which successfully completed its maiden flight in June 2025.

Stripping away those high-sounding terms, this small aircraft is essentially a more rigorous and precise “big toy”. Like those cars and airplanes from my childhood, it serves the same purpose: to allow us to complete a verification in the palm of our hands before facing the real thing. From the simple intuition of toys, to the precise data of prototypes, and finally to the roar of the actual aircraft—this embodies a wisdom of “understanding the big through the small”.

We often feel that terms like aerospace and simulation technology are too far removed from daily life, but in fact, the seed of curiosity about the nature of the world was already planted in the toy box. The child who once pushed a little car across the floor and the graduate student now building models in the lab are, in essence, doing the same thing.

This intuition, nurtured since childhood, later became my anchor when facing complex formulas and tedious models. The simulation logic once hidden in toys was like a flickering lamp—dim one moment, bright the next—that, whenever I groped through the darkness of scientific research, always lit up just enough ground for me to take the next step. Looking back, it was that faint glimmer of simulation that ultimately lit up my future.