"It's hard to put into words." Xiong Jing naturally thought of a word: Bernoulli's fluid principle. "A downwind is when the wind blows the sails and the sails push the boat, but a real headwind is not. If it's a headwind, it's like ...... Standing on the stern deck, looking at the seabirds flying and chirping on the side of the boat, Xiong Jing finally found an example and said, "It's like a seabird flying high."...... The wings of the bird unfold, and the air flow passes under the upper wings of the wing, and the upward and downward rush will generate a lift force to lift the bird's wings.

The true headwind is to use the sail as the wing, but the bird's wing is horizontal, and the sail is vertical. As long as the sail is aligned with the wind direction at a certain angle, like a bird's wing, and the wind on both sides of the sail is slow and urgent, the sail can propel the boat forward. ”

"I see." The left and right history understood, but only understood. Their gaze shifts between the seabird and the mainsail, as if trying to find a resemblance between the bird's wing and the mainsail.

"This sail must not be really against the wind." Xiong Jing added. At this time, there were a few second-year students of the aviation school standing on the deck of the stern building, and Xiong Jing had to say it in detail. "There are two kinds of sails, one is a crosssail and the other is a sylanderer. The sail is like a shield, square and square; Schooner ......" he pointed to the triangular aftermath mainsail. "This is the shoulk."

"The sail is generally used for sea boats that carry goods, or sea boats with a small aspect ratio. These boats are heavy and require a sail to propel them. However, it is difficult for the sail to be really headwindy, and it is too slow to learn the crab to go sideways, and it is better to wait for the tailwind to sail than to sail for a long voyage, so the sailing boat must wait for the monsoon to be downwind before sailing, and it may only sail once a year; The longitudinal sail is used for sea boats with a large length-width ratio, the sea boat is narrow, the loading is small, and the longitudinal sail can be really headwind, and it can be sailed at any time of the year. ”

"What is this sail...... Why can't you really go against the wind? Right Shi looked at the sail and then at the sail, puzzled.

"Because the sail can't turn." Xiong Jing pointed to the front, rear and side branch ropeways on the mast. "When there is a true headwind, the sail must be aligned at an angle to the wind, because of these ropes, the boom of the sail cannot be turned to the right angle to the wind, so it cannot be really upwind."

"Ropes?" The mast is full of ropes, and it is difficult for ordinary people to distinguish how many ropes there are, although all the ropes are just a simple superposition of a sail and a mast, but you can't understand it when you see too much.

"Can you remove the ropes?" Zuo Shi asked again. The ropes were like cobwebs, and his eyes were sharper than the right Shi, and he couldn't distinguish them.

"Yes. But there was only a layer of sails left on the boat, and the mast was low, otherwise it would have been blown off by the wind. It is feasible to sail near the sea, but it is difficult to travel in the far sea, because the sail surface is too narrow and the thrust is too small, so it will still have to sail downwind and cannot go against the wind. "Zuo Shi is actually talking about Chinese-style sails. There is only one layer of Chinese sails, and because there is only one layer, the area of the sail is not enough, and the thrust is not enough. Zheng He's voyage to the West is to sail with the wind, not against the wind, but the Chinese sail is a longitudinal sail, and the wind from all directions can sail, and the sailing does not have to wait for the monsoon.

"It turns out that sails also have strengths and weaknesses." The left history said, and the right history sighed in a relaxed way.

"The cargo capacity of the sea boat, going against the wind and going with the wind, there must be a trade-off between the three." Unlike when he was building the Junior Division, Xiong Jing has now grasped the essence of sailboat design. "This year, it will be launched to be a sailing boat that is really going against the wind, but the cargo capacity of this sailing boat is less than half of that of a normal sailing boat."

"Less than half?" Right Shi was surprised.

"Yes." Xiong Jing is talking about the flying shear experimental ship that will be launched this year. The same 29-meter-long keel (35-meter-long boat), a schooner more than 9 meters wide, and a clipper ship more than 5 meters wide, the difference between the actual displacement tonnage of the two is more than half. The schooners were more than 520 tons, and the clippers were less than 250 tons.

The keel is precious, and even if the flying shears can sail twice a year, it is not worth it. Historically, the flying shear transported mainly tea, or new tea. The other is opium, both of which are lightweight and high-value items. Xiong Jing is still unsure of what to sell, silk, porcelain, tea, spices? Or iron, armor, paper, or even cement?

While he was thinking about the trade goods, the acting captain of the ship, Hong Mou, ordered someone to take the speed, and the hourglass of the timer also began to time. Although track retreat cannot accurately determine the position of the ship, it is not abandoned, and in many cases it can still be used as a reference for the inference of the ship's position.

The sails were fully loaded, and the Shao Si Ming, who was smooth sailing, rode east from Zhu Fangyi like an arrow off the string, and the speed was so fast that the two pawn-wing warships beat the building drum, and the two hundred and fifty men paddled with all their strength to open the way in front of them. After that, the speed of the Xiang Lady was also unabated, and she maintained a distance of about five chains from the Shao Si Ming.

The sails whirred overhead, and the sun was slowly rising, and the sun was shining on the sea, sparkling with gold. The banks of the river were still in full view of the greenery, and the busy farmers in the fields gazed in amazement at the two sailboats heading eastward into the sea, while curious children ran on the shore, but the more they ran, the more they fell behind.

"That's it." Xiong Jing had a smile on his face, and he couldn't have enjoyed the feeling now. The sailors and cadets on the boat also cheered on the other side. This time, they are really going to sea, heading to the depths of the sea that they have never been to before. Only Zhu Zhu, who was going to sea for the first time, and his entourage were very uneasy to grasp a support on the deck, their faces were full of worry, and they did not have the slightest feeling of enjoyment.

"Ask the king to inspect the fairway." Wu Jiheng, who was in charge of piloting, walked over with the channel he had drawn, and he followed the map given by Xiong Jing, and the track was no different from Xiong Jing's own drawing.

"Do you know why?" It was already in the stern, Xiong Jing nodded and was ready to explain the reason to him.

"The big gully travels north all the year round, and this voyage follows the south wind and travels along the big gully, and you can reach the island in a few days." Wu Qiheng was arranged on the Shao Si Ming because of his first graduation grade, and Xiong Jing had previously said in class.

"Yes." Xiong Jing grabbed a pen, dipped it in ink, and redrew a sketch of the East Asian seas. Sketches, like maps, don't show latitude exactly, but the approximate location is good. "Remember! The current within the gully rotates in such a way that Xiong Jing drew a counterclockwise direction, "the gully will diverge northward, between Korea and Yingzhou, and the remaining flow will go northwest into the Bohai Sea, and then go south because of the coastal current." The wind direction alternates between winter and summer, but the sea current remains unchanged for eternity. ”

The king actually taught something new, and Wu Hengheng's face was full of excitement, and he nodded vigorously.

Before Xiong Jing could finish speaking, Fu drew Dongzhou on the paper again, and said, "Beyond the gully, it rotates like this," and he drew a clockwise direction this time. "Go to Dongzhou with the gully to the south of Yingzhou, turn east at 40 degrees north latitude, and then go east along the gully, the best time to sail in June every year, here is the westerly wind belt, it takes six months to reach Dongzhou downwind, rarely more than seven months.

The return journey is to the south along the coast of Dongzhou, the time is at the end of January and the beginning of February, and the voyage is about 12 degrees north latitude and then sails west. Monsoons and ocean currents will blow you back to Middle-earth, and the voyage will take only three months. However, the place you return to is here, Luzon, and you have to cross these islands and continue west to return home. ”

In the 16th century, the Spaniard Urdanetta, with his rich knowledge of navigation, ocean currents, and monsoons, spent ten years figuring out the route of the Pacific Ocean, but now he can easily draw it on paper. After Xiong Jing finished speaking, Wu Jingheng's face turned pale, and he didn't know whether he was excited or afraid.

"The state of Chu urgently needs three grains." Xiong Jing knew it was inconceivable to have an uncrowned young man guide a sailboat across the Pacific, but he was the best of the students, and everyone but him was inferior.

"The people moved to Jiangdong, and the acres of land were all under the fields. Even if you grow millet in the field, the yield of a small mu is less than one and a half stones, and the yield of rice is less than eight buckets. A family of five needs 150 acres to grow millet to survive, and rice is twice as much. The remaining two grains of Dongzhou Sangu are not mentioned, and sweet potatoes must be found and brought back. Otherwise, the Qin army will attack Chu again, and the people will ......."

"The minister swears to die and bring it back to Sangu." Heng's pale face finally returned to blood, and he solemnly confessed that his determination had been made.

"You don't have to bring them all back." Xiong Jing instructed. "Sweet potatoes have the highest yield, and sweet potatoes are enough. The sooner you bring it back, the sooner the counties will be planted, the more grain will be stored in Gaofu, and the harder it will be for the people to starve. ”

"Remember." He nodded heavily.

"Where there are people, there are three grains." Xiong Jing added again. He didn't know what the situation was in the Americas, but since it was a crop, he naturally went to a crowded place to find it. "It is said that hundreds of years ago, the Yin people traveled east to Dongzhou, and it is likely that you will meet the Yin people after you arrive in Dongzhou. Yin people often worship gods from outsiders, and after seeing Yin people, how to get along with them needs to be considered. ”

"Yui." Xiong Jing once talked about Yinren's eastward crossing, and Heng remembered.

"Yes." Xiong Jing only informed him in advance now, and when he saw that he was almost done, he handed the chart to Heng and explained: "Burn it after remembering it." ”

It is now March, and next year it will set sail from the 40th parallel north latitude to Dongzhou, and the six-month voyage will arrive at Dongzhou at the end of the year. If they were to return in February, the ocean-going fleet would have two months at most to look for the Indians and for sweet potatoes.

Two months ......, in the vast Dongzhou continent, two months is obviously not enough, unless the Indians live by the sea. The ideal situation is to stay in Dongzhou for a year, spend a year and two months looking for Sangu, and you can always find something in such a long time. After finding it, it will be in June or July of the third year.

In June and July of the third year, what did the Qin Congress do in three years? Vachu? Var Zhao? Swallow Han and destroy Wei?

After retiring from the army the year before last, the Qin State reined in his minions and became unusually quiet. Although Korea consumed 70,000 or 80,000 people in the Battle of Aocang, Korea was not annexed by the Qin State, and the harmless Qin State made people very unaccustomed to it, and they always felt unreliable.

In the stern of the Shao Si Ming, Xiong Jing was thinking about what the Qin State would do in the next three years, but he didn't know that there was another urgent message from Yingdu not long after the boat trip, and this time Concubine Zhao no longer hid it, because the entire Yingdu knew all about the immortal medicine.