Why is the speed of the aircraft carrier at around 30 knots? How fast is that converted to ground transportation?

The speed of an aircraft carrier is one of the important criteria for measuring the combat effectiveness of an aircraft carrier. The faster the aircraft carrier sails, the faster the aircraft carrier's combat deployment will be, and the more flexible the military's tactical planning will be. If we look at the data of the aircraft carrier, we will find that the speed of the aircraft carrier is around 30 knots, and the speed difference between each other is generally not more than 5 knots. Then why the speed of the aircraft carrier is around 30 knots? How fast are these 30 knots on land?

"Knot" is a speed unit born in the age of great navigation. In the early age of great navigation, due to technical limitations and the lack of reference objects at sea, it was difficult for people in the sea to measure how far the ship ran and how fast the ship was. So there are crew members who count with hourglasses and ropes. They would tie knots at intervals on the rope and drop one end of the rope into the water.

When the ship sails at a constant speed, it will smoothly drag the rope into the water, and the sailors can use the hourglass to calculate the time, and then they can calculate the speed of the ship through the number of knots in the rope. Because of this unique calculation method, the early "section" was also called "chain". This unit later became a "section" because of translation problems when it was introduced to China.

Because the length of each section of the rope is fixed, each "section" is regarded by the sailors as a mile traveled by the ship on the sea, that is, a nautical mile. One nautical mile is equivalent to 1.852 kilometers. In other words, the speed of an aircraft carrier at 30 knots is equivalent to running about 55 kilometers per hour on land.

Why can an aircraft carrier only run 30 knots?

Many people may be quite surprised when they see this number. After all, even if it is a motorcycle, the speed of the accelerator is more than 55 kilometers per hour. As the most important weapon of the country, the aircraft carrier weighs 10,000 tons, and its speed is actually slower than ordinary transportation on land. Among them, there is a reason why the aircraft carrier is slow. Judging from the current human speed technology tree, it is not easy for the aircraft carrier to maintain a speed of 30 knots.

speed and resistance

The forward speed of an object is not only its own forward force, but also related to the fluid resistance it receives. The surface of the earth is not a vacuum area. Sea water and air are both fluids, and any object moving forward in these fluids will be subject to certain resistance. We humans cannot feel this drag simply because we are too slow, and we would easily feel it if we stuck our hand out the window of a speeding car.

The resistance provided by the fluid is related to its density. When an object moves through a fluid, it is equivalent to pushing away the molecules that make up the fluid. A less dense fluid has fewer molecules in the same volume, and it is much easier for a moving object to push it away. The opposite is true for dense fluids, so objects moving forward in the air experience far less resistance than sea water, and the speed of an aircraft carrier cannot be compared with that of land vehicles.

Although fluid will bring resistance to advancing objects, we humans can also use this resistance. If we look at the power system of a large ship, we can see that all large ships are driven by propellers. When these propellers are working, they will discharge part of the seawater to the rear of themselves, forming seawater convection, allowing part of the seawater to push themselves forward, thereby achieving the effect of saving energy.