Chapter 241： To take off

This is a classic air pressure test.

The device with the highest technical content is probably this glass. It was also made by Xia Fan commissioned by Luo to lightly fired it with dragon scales. Although the sea sand has a deep green color, it does not hinder its excellent light transmission.

Put the four candles in a basin filled with water, then light the candles and buckle the glass upside down.

In full view, the candle quickly ran out of oxygen and went out.

Then the water surface inside the cup rose rapidly at a speed visible to the naked eye.

In less than a few breaths, the water pouring into the cup crossed the basin outside and rose to almost one-third of the wall of the cup. From a distance, it looked like a new "hill" had risen in the basin.

Before that, the inner and outer waters were still at the same level!

"How does this water... move?"

"It feels like being sucked up by something!"

The children's interest was immediately mobilized.

"You might as well think about why this phenomenon occurred." Xia Fan once again looked at everyone-in fact, he arranged for the Privy Council among the observers, just to prevent cold spots caused by no answer. .

But this time someone gave the answer in advance.

"What you want to say is that the gas in the bottle is exhausted, causing the outside gas to squeeze the water surface and push the water into the bottle?"

"Correct." Xia Fan followed the prestige somewhat curiously, and it was a little girl who caught his eye. Seeing her location, it should be a guest invited by Fang Xiandao.

To be honest, although this experiment is a classic, it is not as shocking as a hemispherical experiment. It takes a circle to understand the principle. The other party seems to be young, but can think of this level quickly, is it - she is also a living dead?

"Then can I ask a few more questions?" Qian Yan got up from the chair, which made her suddenly shorter. "The person in front, please let me."

Probably I have never seen such a magnificent little girl, everyone involuntarily vacated a passage.

"Sir Qianyan..." Fang Yanni's face turned pale.

"Don't worry." Fang Xiandao comforted him, "The Xia Fan I know is not the kind of person who bullies others."

On the other side, Xia Fan nodded with interest, "Of course, you said."

"Since there is pressure in the air, why don't we feel tired, even if we relax, we won't be crushed?"

"The same reason as this bottle, because we also have air in our body, which is offset by the inside and outside. If the air is taken out, the weight is enough to press a person."

"Then what is the air? Does it have a substance? Can it be directly touched?" Qianyan asked.

If it's the imaginary and realism of the past, you will definitely avoid answering such questions directly, and instead talk about profound and profound principles.

"Of course it does." However, Xia Fan did not forcefully change the subject. "You can understand gas as a thinner water, so when the temperature is low enough, it will freeze like water and become visible to the naked eye. "Ice bumps"-I think at that time maybe you could see more intuitively that you were touching an entity."

"The air-can it be frozen?" Qianyan couldn't help but stunned, she did not expect that she would get such an answer, "How low is the temperature?"

"It is much lower than the freezing point. This temperature may be difficult to achieve at present, but as long as you work hard in this direction, I think you should be able to see one day-frost formation does not condense the water vapor floating in the air into ice ?"

Qianyan showed a pensive look, and after a long time she looked up, "These are all your speculations, right?"

Xia Fan did not deny it.

She hesitated, "That is to say... It is still doubtful whether the conclusion is correct."

"I know it is really hard to imagine. This is also a great pleasure of studying things: from the details that can be seen everywhere, the principles behind things are deduced and applied to a wider range of fields, even if it is counter-intuitive." Xia Fan turned to high interest. Students, "Everyone is quiet! I have also prepared another experiment, which will let you see that not only does the air fill the surroundings like water, but people can also use it to do incredible things!"

This experiment is no longer limited to the glass bottle, but the world is the stage.

A simple air pressure fun experiment certainly can't satisfy Xia Fan. He strives to make this public class the first shot in the school's reputation, so he didn't leave any hands.

And to show the charm of air, what can be more influential than the representative machinery that integrates various aerodynamic studies and represents the conquest of the sky by humans?

At his sign, two guards carried a biplane into the entrance hall.

Although its size can only be said to be at the level of a model, it instantly attracted everyone's attention with its unique shape-it looks a bit like a kite at first glance, but everyone quickly realized that it is much thicker than a kite and its size is close to half human High, the wings are more than an arm. This thing doesn't move when it is placed on the ground, and its weight is evident.

The next step is to build a runway about 100 meters long with smooth wooden boards.

Xia Fan originally thought that the key to the biplane model is that the electric motor is difficult to polish by hand. As a result, Mo Yun gave him a surprise. The slender iron rod used as the rotor was shaped by the latter with precision hands. . In contrast, the copper wires and magnets surrounding the rotor are only the experience accumulated in the four-wheel drive era, and it does not require much effort.

To provide energy for the engine are two sets of soil capacitors. They are made up of layers of gold foil and lacquer paper. In order to prevent the insulation layer from being broken down, the surface of these lacquer papers is also coated with sealing wax to ensure that the electric charge will not fly up and down.

To charge the capacitor is a streamer technique. Even after thousands of shocks, Xia Fan burned several prototypes before he mastered the strength of charging the local capacitors.

Of course, he can also hold the wire in his hand to directly provide energy for the model machine, but this kind of "wired remote control" is easily reminiscent of a kite, and the feeling of freedom to chase the wind is unavoidable.

"What is this?" Qianyan couldn't help asking.

"A vehicle that allows people to fly in the air, but it's just a model now."

"Soaring...in the air? You mean can it fly?"

This sentence is also everyone's question, after all, the model machine looks too heavy and clumsy.

"It is precisely because the air flows like water, so as long as it is used properly, it can hold things hundreds of times heavier than itself, just like a ship that weighs a lot can only float on the sea." Xia Fan replied with a smile. Seeing that everything was ready, he pulled down the switch that connected the circuit.

The blades located in the nose of the aircraft spun quickly and made a huge hum!

The motor does not need assistance, as long as there is power supply, it will run with maximum distortion.

Driven by the propeller, the biplane began to advance slowly and faster and faster. Until the pressure difference between the upper and lower wings exceeded the weight of the airplane, it seemed to be lifted up by a pair of invisible hands, and suddenly left the ground under the incredible eyes of more than two hundred people, and soared into the air!

The scene was silent for a while.

Xia Fan knew that the two sets of capacitors could only run for tens of seconds, after which it would fall to the ground under the pull of gravity. But just these tens of seconds is enough to leave an indelible impression in people's hearts.