Back in 1978, I was admitted to Northwestern Polytechnical University.

Chapter 82 Fighter Jets Require Standardized Production
Due to the large processing errors, experienced craftsmen used various methods during installation: filing with a file, then hammering with a sledgehammer, switching from rubber mallets to wooden mallets, and from wooden mallets to iron mallets... This scene was even made into a movie, showcasing the superb skills of Eastern workers...

The result of this is that they cannot be interchanged. Not to mention different aircraft, even the two engines of the same aircraft cannot be interchanged!
Back then, two J-8 fighters flew to Grumman for avionics upgrades, and this shortcoming stunned the Americans; they never dreamed it would be like this!

"Do the aircraft parts need to be swapped?" Master Liu asked.

"That's right, they must be interchangeable! That way, if parts are missing on the battlefield, we can simply take them from other aircraft and use them interchangeably," Qin Liang said. "If we want our aircraft to go global, we also need to focus on interchangeability, strive to improve standardization, and even when riveting, the position of every single rivet must be exactly the same!"

This is simply unimaginable for everyone, but... the next step is to engage in military trade. The aircraft being produced now are for export. This is different from previous military aid, which was given away. Even if it was rubbish, it had to be properly marketed as a sale to someone else...

Old Tu took a deep breath: "Liangzi is right. We have already opened up the military aircraft market. In the future, we need to put more effort into standardization and introduce the US military's quality management system for fighter jets... Wait, what does this have to do with flutter?"

“Every actuator cylinder produced by Master Liu meets the size requirements, but there is a significant error between these four actuator cylinders,” Qin Liang said. “This causes problems with the coordination between the four actuator cylinders when they are installed, resulting in wing flutter.”

The design had already taken into account the impact of chatter, but the large manufacturing error and the inconsistent mass of the four actuator cylinders led to increased elastic vibration of the internal structure, which triggered chatter at low speeds.

Modern fighter jets require extremely high manufacturing precision. Take the DSI (Diverterless Supersonic Inlet) intake as an example. Aircraft engineers worldwide know that using this bulge to replace the adjustment device can reduce weight and system complexity. However, apart from the United States, only the East can use it, and it is widely adopted in the East. Why?

Of course, it's because this bulge requires very high machining precision; if it's even slightly off, then all the design will be wasted!
"Sigh, I didn't expect it to really be my fault..." Master Liu sighed, "My hands..."

"Master Liu, your skills are excellent. Just pay attention to standardization in future production. The extensive production methods of the Soviet era are no longer suitable for export production. We need to improve our production technology as soon as possible and strive to integrate with the world more quickly..."

"Yes!" Master Liu nodded. He felt guilty that the parts he produced had malfunctioned. Now that he knew the cause, he would work harder in the future!

As for Engineer Huang... his feelings were complicated at this moment. Should this so-called standardized production be promoted to Factory 112? Forget it, we're not involved in foreign trade, let's wait!

As if struck by a thought, Engineer Huang said, "What about the airflow separation problem at high angles of attack?"

Airflow separation on wings is a major problem. Early aircraft had wing fences to prevent airflow separation on the wings, but that only prevented lateral airflow. The problem now is longitudinal airflow. How can we solve this?
"Cold salad."

"What do you say?"

"Northwestern Polytechnical University is just an ordinary university. What can we do? It's just wishful thinking."

This is venting his dissatisfaction! "Liangzi, you must have a solution too, right?" Old Tu said.

Qin Liang glanced at Engineer Huang: "Well... we've got enough time for today, let's talk about it tomorrow."

The meaning is clear: I know, but I'm not telling you!
Huang's face flushed red and then turned pale. Finally, he took a deep breath and said, "Qin Liang, don't be angry. I was wrong just now. I shouldn't have underestimated Northwestern Polytechnical University. Please... please don't hold it against me."

“Liangzi, Engineer Huang is an expert from Shenyang. He was invited to help us solve the problem. Why don’t you tell us your thoughts?” Old Tu knew that Qin Liang was young and impetuous, but he was also afraid that he would offend the people from Shenyang and that it would have a negative impact on his future prospects.

"Yes, we install flaps not just to help improve performance during takeoff and landing. These maneuvering flaps can be used in all airspace."

Everyone's eyes widened: "How is this possible?"

"Yes, during takeoff and landing, the pilot can control it manually. But if it's to be used across the entire airspace, then it needs to be automatically controlled. Do we... have that capability?"

"Since we can modify the J-7's air intake cone to be infinitely adjustable, why can't we do the same with the flaps?"

Back when the MiG-21 was first introduced from Russia, it used a three-stage adjustment scheme. Later, when Factory 132 improved it to the J-1, it became stepless adjustment, thereby improving the intake efficiency at different speeds.

"You mean, connect it to the atmospheric data computer?" Old Tu's eyes widened.

“That’s right!” These seniors are very capable; just mention one point and they can keep thinking!
"We use an atmospheric data computer as the command computer for the maneuvering flap control system. We have programmed control laws into the system to show how the flap deflection angle changes with the angle of attack and Mach number. This allows us to obtain the most suitable flap deflection angle at any speed and angle of attack, thereby solving the pitch control problem of the Super-7 fighter jet and ensuring overall flight safety."

Aircraft with mechanical and hydraulic controls can still be controlled by computers! The Tomcat fighter jet is an example of this; its variable-sweep wings automatically change their sweep angle according to flight speed, and it also uses a scheme where atmospheric data is used to output control commands from a computer!

"This idea is feasible, but designing a closed-loop servo control system that can meet the requirements and is safe and reliable is not easy!" Engineer Huang was also shocked, but... he also knew just how difficult it was to develop such a system!
“That’s right, it’s not easy,” Qin Liang said. “However, since it’s a partner of Factory 132, Northwestern Polytechnical University can still take on such a heavy responsibility! There’s no way around it, our Northwestern Polytechnical University’s dreamers just love to dream.”

Huang smiled wryly. This Qin Liang was indeed someone you couldn't afford to offend!

"Qin Liang, can we install the maneuvering flaps you mentioned on our J-8?" Engineer Huang couldn't resist the temptation of the design. In the West, maneuvering flaps were already mature in the 1950s and 60s, but unfortunately, Eastern fighter jets never had the opportunity to be equipped with them. If the J-8 were equipped with them, wouldn't it be able to handle both high and low altitudes, high and low speeds?

(End of this chapter)