Han Zhen looked from the tent and saw a large circle of people yelling happily on the school ground outside the gate, while a huge thing like a big white mushroom floated on the ground, swaying left and right under the breeze, and was still expanding and growing.

"Shishou, this is brought by some scholars from the Royal Academy. It is called a 'hot air balloon'. It is said that it can fly a hundred feet high and look dozens of miles away. I tried it a few days ago and was almost blown away by the strong wind. It was just a group of children making trouble!" Tian Zhong said with a smile on his face.

"If they can fly a hundred feet high as they say, they can observe the enemy's formation, observe the enemy's movements at any time, and mobilize troops to deal with it in a targeted manner." Han Zhen was very interested and immediately thought of his military application, "Let's go and have a look!"

"Since Shushu is interested, let's go and have a look!" Tian Zhong agreed to see that the aides of both sides were still communicating and collaborating details, without any trouble.

Accompanied by several personal guards, the two left the tent and went to the schoolyard. It was already noon and the weather was clear and there was a breeze. They walked forward quickly and were accompanied by the roar of "hiss...", and the "white mushroom" in front of them became larger and larger. It was simply a giant, six feet tall and more than five feet in diameter, which was taller than the city wall in the distance.

"Supervisor, General Manager!" Seeing the two of them coming, the onlookers stood attentively and saluted them, making way for them.

"How come this looks like a head of garlic?" Han Zhen walked up and looked up, and then he saw that the air was floating in the air was a huge airbag sewn with silk cloth. There was a railing hanging at the bottom. There were two men operating a device similar to the "fire cabinet" and spraying a raging flame into the airbag. The deafening hissing sound was the sound of the flame burning violently.

"General!" A teacher with a crown and hat led two scholars who were assisting in the operation on the ground and bowed.

"This... this 'hot air balloon' was made by you. Can you take people to the sky?" Han Zhen asked.

"Zou Qing, the teacher of Xiaguan Royal Academy, this item was designed and manufactured by His Majesty. We conducted a test flight in Beijing, carrying two people and a total of two stones to a hundred feet high. In theory, it can fly higher, but it has not been verified yet." Zou Qing introduced.

"Oh, it turns out that it was His Majesty's wonderful idea. This was also what His Majesty asked you to bring?" Han Zhen nodded. Almost all the old people in the court knew that the emperor liked to make some ingenious things since childhood, and gave surprises from time to time, and many of them were already practical, so everyone had already been accustomed to it.

"No!" Zou Qing waved his hand and said, "Your Majesty often teaches us to apply what we have learned. The teachers and students in the academy thought that hot air balloons could climb high and look far, predict the enemy in front, and use them to correct artillery. Although we cannot go to the battlefield to kill the enemy, we can assist the army in fighting, so we asked Your Majesty to take the right to serve in the army."

"Well, it's very good!" Han Zhen nodded and praised, "What's the reason why this thing can really fly into the sky!"

"Shu Shushou..." Zou Qing pondered for a moment, thinking about how to use the simplest words to make an outsider understand the truth. "Shu Shushou should know that the boat is walking on the water because the buoyancy of the water is greater than the weight of the boat. This is the same as the principle, the air also has buoyancy. After the air is heated, the density decreases and the weight is less than the weight of the air, so the air bag can float in the air."

"This... what is buoyancy, what is density, can this air lift heavy objects?" Han Zhen said in confusion and suspiciously.

"It's no wonder that Shushu has never learned the 'normal principles' and does not understand all things!" Zou Qing knew that he didn't understand at all, and then thought about it, "Shishu should have seen Kongming lanterns, which is the same as being able to fly into the sky."

"How can you speak to Shangguan like this!" Seeing that he was arrogant, Tian Zhong dared to laugh at Han Zhen for his ignorance and glared at him.

"The officials have no such intention, but the truth cannot be explained clearly in a few words. It must be understood through systematic learning!" Zou Qing was not afraid, and said with a slight politeness, neither humble nor arrogant.

"It's okay, can we go to the sky to see it together?" Han Zhen understood that what they were talking about was the truth, and he did not understand, but seeing the hot air balloon gradually erect and the hanging basket slowly left the ground, he still couldn't suppress his curiosity. After all, from ancient times to the present, no one can fly to the sky except the legendary gods.

"Sir Shu is the commander of the three armies. He is responsible for heavy responsibilities. How can he take risks?" Zou Qing refused without thinking.

"Can he let him go up and watch?" Although he was ready to move, Han Zhen thought of his responsibilities and suppressed his curiosity and pulled him to watch the fun with an aide.

"Okay!" Zou Qing thought about it, maybe he felt that refusing repeatedly was really a gift, so he agreed. He called a scholar in the hanging basket and let him get on the hanging basket.

After repeated inspections, Zou Qing issued an order to release the fire. The squad in the hanging basket increased the firepower. The auxiliary squad on the ground released the cables, and the hot air balloon began to rise in the air amid the screams of everyone. Ten, twenty, thirty zhang... The cables on the ground were constantly released, and the hot air balloon became higher and higher, and finally stopped around thirty zhang and slung in mid-air.

The hot air balloon was not stuck in the air for a long time. After about two quarters of an hour, it began to slowly descend with the cooperation of the ground personnel and finally landed smoothly. Han Zhen immediately stepped forward quickly and saw that the two men who operated the hot air balloon were fine. His staff member was excited or scared, his face turned pale and trembled all over. With the help of everyone, he got off the hanging basket tremblingly.

"The Du Shu, the general manager, it's such a good thing. Watch it from above. The situation within the city and outside the city is 30 miles away, and the enemy's defense and mobilization can be seen..." As soon as the aide stood firm, he couldn't wait to report.

"Okay, you can draw what you see into a picture and record it first!" Han Zhen was also extremely happy. He asked someone to send it back to the account to rest.

As a veteran on the battlefield who has experienced many battles, Han Zhen understood that the most worrying thing on the battlefield was that he could not know the distribution and mobilization of the enemy's troops, so he immediately discovered the huge value of the hot air balloon on the battlefield. With this kind of exploration tool, he could see the enemy's movements and respond to the enemy's first step.

You should know that nearly twenty enemy and us are facing each other, with concentrated troops and tight defenses, wide battlefield, flat horses, and no clear depth arrangements can be seen with eyes, and it is difficult for scouts to penetrate into the hinterland of the enemy camp and explore internal details. It is even more impossible to discover the enemy's dynamics in time, and the time to deal with them is often very limited after discovering them.

The city wall of Daming Mansion is even taller, with three steps and one post on the city, and one sentence on ten steps. The soldiers are patrolling each other. It is more difficult to sneak over and enter the city than climbing to the sky. Even if you can set up a watchtower to see the situation in the city, your current technical level is more than ten feet high. You can barely see the situation in the city clearly.

But it is different with hot air balloons. As the saying goes, stand high and see far. It can look down at the entire battlefield in the air that is dozens of feet high, with a radius of more than twenty miles. With a telescope, you can see the enemy's every move. In battle, you can also monitor the entire battlefield in real time, provide timely warnings for your side, adjust the troops to the enemy's movements, and test the results of the battle.

Therefore, his attitude towards the scholars from the Royal Academy also changed. After finishing up, they were invited to the commander's tent and talked to him. Tian Zhong also went to his subordinates to place them near the Central Army's tent, providing the best camp and food, and also dispatching a team of soldiers to be responsible for their safety and cooperate with their work.

Back at the Central Army, Han Zhen and Tian Zhong asked Zou Qing in detail how to use hot air balloons and put forward their own ideas. He hoped that the hot air balloons could be launched day and night, monitor the dynamics of the enemy and battlefields in real time, and provide intelligence support for combat. He even imagined using hot air balloons to carry soldiers across the Daming Mansion wall and airborne directly into the city, or throw grenades to the enemy from above to attack the enemy.

However, Zou Qing's answer disappointed Han Zhen and others. He said that the hot air balloon is subject to climatic conditions such as wind force, wind direction and air pressure, and cannot fly all day long, and it is impossible to control its course at present, and it is difficult to fly over the enemy to fight. Even if the wind direction is appropriate, the hot air balloon currently used can carry up to three to four thin soldiers and cannot carry out large-scale airborne operations.

What is even more difficult is that the fuel used by hot air balloons to heat the air is refined 'temperature oil', and the current acquisition of temperature oil is purchased overseas through trade by merchant ships, and the price remains high. However, this is not the biggest problem. Due to the fact that the current refining equipment cannot be produced in large quantities, the fuel is extremely precious, making it difficult to maintain long-term flights.

Although it is difficult to satisfy all Han Zhen's ideas, Zou Qing promised that as long as the weather conditions allow, he guaranteed to fly two take-offs and lands every day, survey the terrain, and detect the enemy's movements; when the battle breaks out, they will also extend the time of stagnation to provide them with real-time intelligence and assist the army in combat.

It was originally an unexpected surprise. Although Han Zhen and Tian Zhong had regrets, they were not dissatisfied. The two sides agreed that the scholars would drive hot air balloons, and they were equipped with two observers to take off together, responsible for observing the enemy's movements and contacting the ground. What made them feel a pity that there were only two hot air balloons available at the moment, making it difficult to conduct comprehensive monitoring of the entire battlefield.
Chapter completed!