"Sound propagates in media of different densities. What factors are related to its propagation speed? What are the changes in the waveform of the echo?" - "Studying Things to Know", Sound Waves and Media, Feng Haizhou, a bachelor of the Ming Dynasty.
"The Piano curve fills a square with a line. Is it one-dimensional or two-dimensional?" - "Studying Things to Know", a mathematical model of spatial geometry, written by Giupese Piano, an Italian national in the Ming Dynasty.
"Plant Physiology, the Beginning of Photosynthesis." - "Investigating Things to Know", Plant Physiology, by Jeanne Sernabière, a naturalized Ming Dynasty citizen from Switzerland.
Zhu Zaiming put down the Gewu Bao in his hand and rubbed his head.
Gewu Bao has been published for several issues, publishing important achievements in the field of natural sciences made by mankind in the past ten years.
To be honest, Zhu Zaiming has not forgotten the photosynthesis of plants, but the Peano curve is the geometric application of high-end mathematical models.
Zhu Zaiming felt that he could not understand the "Ge Wu Bao" more and more.
It's a good thing that you can't understand it, because it shows that the study of physics in Ming Dynasty is flourishing.
At this time, a telegraph operator hurriedly sent a telegram to the Bagua Building and delivered it to Zhu Zaiming.
In the afternoon of the same day, the battleship Zhenyuan, cruiser Pingyuan, destroyer Chaoyong and supply ship Xinxiang set off from Chongming Island Naval Port and sailed towards the Pacific Ocean.
…
18,000 meters altitude.
night.
On the Pioneer, 13 people huddled together at their posts, and the creak of the steel frame deforming came from the airship.
At this altitude, it's minus 60 degrees at night.
Although the airship was protected by a canvas shell, frigid temperatures penetrated the cabin.
Everyone wrapped up their military coats tightly, but their hands and feet still felt cold.
Zhu Xianxue sat on the podium, close to Li Siming, and asked tremblingly.
"Captain Li, why doesn't the crunching sound stop on the airship?"
Li Siming exhaled a breath of hot air, tightened the collar of his military coat, and said: "It should be the effect of thermal expansion and contraction. The assembly of the airship is completed on the ground, and the working temperature is 20 to 27 degrees.
Now we are at an altitude of 18,000 meters, with a temperature of minus 60 degrees. The size of the steel frame has shrunk, and gaps have appeared in the riveting between the steel frames.
The steel frame deformed under the blow of the airflow, which is the origin of the sound. "
Li Siming's heart was pounding, there was one more thing he didn't say.
That is, at minus 60 degrees, the steel frame becomes brittle and is very easy to break due to rapid stress changes.
This is also the reason why the Pioneer dare not descend directly.
Once the altitude drops and the temperature rises, the rivet joints are tightened again, and the huge stress changes make the keel possible to break.
I was careless. I shouldn't have taken the risk of ascending in search of airflow to return yesterday.
In short, Li Siming regrets it very much now.
“So, let’s do nothing now and wait patiently for the next day.
When the sun rises and the temperature gradually rises, we can safely lower the altitude. "
Zhu Xianxue listened, wiped the cold sweat from his forehead, looked at the soldiers who were also huddled at each post in front of him and murmured: "I hope everyone is safe."
As soon as he finished speaking, everyone heard a sudden strange sound coming from the airbag compartment above the cab.
Then there was a series of sounds such as "boom~", "hoo", "click" and so on.
The airship seems to be descending, and getting faster and faster!
Li Siming was sweating profusely and immediately reminded a few people.
"Don't move, I'm going to check what's going on first!"
After Li Siming finished speaking, he climbed up the spiral staircase gently.
He didn't dare to move too much, so he could only move up cautiously.
When he climbed onto the iron bridge above the keel, he was stunned by what he saw.
Only the rivet of a steel cable was missing. The steel cable was hanging from the top of the airship, swinging irregularly.
Three of the surrounding airbags were broken, and the surface of the airbags was dented inwards visibly.
"Holy shit!"
Li Siming cursed secretly and quickly returned to the cockpit. At this time, he could no longer control so much.
he shouted as he ran.
“Three airbags burst.
Everyone moved and opened the portholes on both sides of the canvas protective shell to allow the hydrogen gas to dissipate at an accelerated rate.
All lead-acid battery packs are disconnected and all cable clamps are loosened. Remember the operation essentials and there should be no obvious sparks.
The telegraph operator turned on the radio and used the "Tai Shang Lao Jun" emergency power supply to send out a distress signal.
Finally, everyone put a life jacket on me, an emergency bag tied around my waist, and a parachute on my back. "
Following Li Siming's instructions, everyone moved, and Zhu Xianxue also put on the equipment with Li Siming's help.
"Please help! Pioneer crashed at 6:07 a.m. Jinling time, location unknown..."
"Please help! Pioneer crashed at 6:07 a.m. Jinling time, location unknown..."
"Please help! Pioneer crashed at 6:07 a.m. Jinling time, location unknown..."
After the telegraph operator connected the emergency power supply, he sent three distress messages through the telegraph machine.
Then the incident was briefly sent out.
This process has been repeated ever since.
As the airship descended, the creaking sound from the keel above became more and more obvious.
The telegraph operator even felt that the airship was becoming more and more unstable. This shaking in the wind seriously affected his message sending.
In the cab, the helmsman worked hard to turn the rudder to control the attitude of the airship. The steel cable connected to the rudder above the deck pulled the cross rudder at the tail of the airship.
At the four propellers of the airship, the soldiers worked hard to control the propellers by hand cranking to provide a small amount of power to stabilize the airship's attitude.
In front of a porthole, a soldier was quickly explaining the escape methods to Zhu Xianxue.
"Your Highness, if the airship is really out of control, pull the red handle on the right and the portholes will fall off automatically.
When it's time to jump out, spread your hands and legs as you fall, making sure your body is facing down.
Don't open the parachute in a hurry. Feel the airflow next to your ears. When the airflow gradually stabilizes, open the parachute.
Find as many islands as possible and land on them!
…”
The soldier chattered a lot. Zhu Xianxue listened hard and kept repeating the soldier's words.
In the air bag cabin, Li Siming was trying to save him.
The buoyancy provided by the airbag at the front of the airship was seriously insufficient, and the airship gradually lost its balance, with its head facing down and its butt pointing up.
What's more serious is that the severe tilt caused the lead-acid battery packs to collide together, and one lead-acid battery fell from the frame and hit the steel frame below.
"Zi~"
There was a flash of electric sparks, and the casing of the lead-acid battery ignited an open flame.
"It's over!"
Li Siming gave up the rescue airbag and started yelling.
"Everyone, abandon ship!"
The two soldiers who were still fighting against the airbag in the airbag cabin quickly slid down from the steel frame, grabbed the steel frame and moved quickly towards the cab.
If Zhu Xianxue were not here, they would jump out of the emergency windows on both sides without hesitation.
The two soldiers and Li Siming went to the cab in tacit agreement.
In the cab, the airship tilted so severely that it was difficult to stand on the deck.
The helmsman firmly stabilized the rudder and made the final resistance.
Two soldiers were wrapping some supplies in tarps and connecting them with canvas straps.
On the correspondent's chest are bundled radios and batteries, also wrapped in tarpaulin.
The portholes on both sides have fallen off.
It's time to escape.
Li Siming and a soldier each held one of Zhu Xianxue's hands and said, "Your Highness, hold on to both of our hands and obey my orders during the descent!"
"One, two, three, jump!"
Li Siming pulled up Zhu Xianxue's windproof glasses, fixed a signal rod on his ankle, and together with the soldiers, pulled Zhu Xianxue and jumped out of the porthole.
