Rebirth of the 1980s: The Military Industry Empire

Anyone with helicopter piloting experience or knowledge would know that there's a professional term in helicopter operation called "collective pitch". This collective pitch lever is usually on the left-hand side. When the pilot pulls up the collective, the rotor blades above will emit a howling sound, and then the helicopter will lift off the ground.

What's the principle behind this? Is it the throttle?

The collective pitch and throttle are connected, but the rotor's ability to go from no power to outputting power relies on the change in blade pitch. Blade pitch is the angle of the rotor blades. While the rotation speed remains constant, the power output can be changed by altering this angle.

A simple analogy is a fan blade. If the blade isn't angled, if it's straight, then there's definitely no wind. As the blade slowly angles, the wind will become stronger and stronger.

Variable-pitch propellers emerged during World War II, initially used on airplanes.

For propeller-driven aircraft, people usually only talk about the engine's horsepower, never about the engine's thrust. This is because the thrust is related to the propeller's efficiency, and the propeller's efficiency varies in different states. If the pitch can be changed, optimal power output can be obtained. Therefore, by the later stages of World War II, most propellers were variable-pitch propellers.

Propellers are used not only in airplanes but also in ships. Ships navigate on the water by the propeller churning the seawater. Common propeller blades are fixed, either cast as one piece or milled out. These propellers can only rotate in a fixed manner and cannot be matched with different seawater flow rates or ship loads.

The West entered the variable-pitch propeller era in the 1930s and 40s. Whether it was warships or civilian ships, they used variable-pitch propellers to improve propulsion efficiency and also to reverse.

That's right. If the blades become flat, then no power is output. What if the blades continue to change? Then the direction of the blades is reversed. This way, while the direction of the drive shaft's rotation remains unchanged, the thrust provided changes direction.

On ships, the reverse function is essential, not only when entering and leaving ports but also when decelerating, to activate the reverse function to obtain reverse torque. So, how can a ship reverse?

Different power systems have different functions. For example, low-speed diesel engines can directly reverse. Therefore, the diesel engine is directly connected to the propeller via the drive shaft, without even needing a reduction gear in between. When reversing, the diesel engine is simply reversed.

What about steam turbines? Steam turbines may have dedicated reversing turbines. After steam enters, they reverse. If not, then the transmission system has to be modified, adding a reversing gear on top of the reduction gear.

Especially for ships driven by diesel engines, a reversing gear is essential to reverse the drive shaft.

However, this undoubtedly increases the complexity of the transmission system. Especially in combined diesel and gas power systems, a diesel engine and a gas turbine form a power unit through a set of reduction gears, driving a propeller at the stern. Because the rotation speeds of the two are different, the reduction gear is already very complex, and adding a reversing gear would be even more troublesome.

What to do?

"President Qin, do you have the manufacturing technology for variable-pitch propellers?" Everyone was stunned.

"This variable-pitch propeller sounds mysterious, but it's actually not that difficult. It's just that there's a set of structures inside to push the blades to change the angle of inclination," Qin Yang said.

The earliest type was pushrod-style, which involved placing a pushrod outside the drive shaft and using the pushrod to change the angle of the blades. Aircraft almost exclusively use this structure. However, propellers on ships are relatively large, so the mechanical device is integrated into the propeller hub, with the technical name of "in-hub hydraulic cylinder."

This thing tests processing technology.

"President Qin, do you have this technology?"

"President Qin, this is too difficult. Multi-axis联动 CNC machine tools are required to ensure accuracy."

Everyone seemed to think that President Qin might not be very familiar with shipbuilding and made such a guarantee rashly, so they reminded him one after another.

Qin Yang smiled: "Of course I know that the required processing accuracy is very high. There must be world-class processing machine tools and advanced programming technology. However, we have to try it. If we don't try, we can only be controlled by others forever."

"Yes, we can't always purchase propellers from abroad. We must have our own procurement capabilities."

"President Qin, how do you plan to solve the problem of CNC machine tools?"

Machine tools are the mother machines of industry. Whether machine tools are advanced is directly related to whether the processing technology is qualified. Advanced Western multi-axis联动 CNC machine tools have always been embargoed to the East. Although the East has obtained CNC machine tool technology from the West, they are all ordinary ones. High-end multi-axis联动 has never been obtained.

"We've already solved it. Our Factory 960 imported one from the West to process the sabot of the tail-stabilized discarding-sabot armor-piercing projectile. The principles are the same. Over the years, we've long been proficient in using that machine and have also mastered the principles."

Our Factory 960 has this!