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

Chapter 184: The Air Force's Number One Project – Can I Read It Freely?
Airborne early warning aircraft: a force multiplier for air combat!
By placing radar in the sky, everything around us can be seen clearly! At the same time, we can also command our own fighter jets to fight through data links!

Without early warning aircraft, we cannot win future high-tech wars!

"Well..." Old Lin hesitated for a moment before saying, "Your Northwestern Polytechnical University has single-handedly promoted the development of our Air Force's equipment, so we won't keep it from you. Our Air Force actually has the KJ-1 project, which has been underway for almost ten years... Since we're here today anyway, let's go, I'll take you to see it!"

Currently, this project should still be the Air Force's top priority project, and it will never be leaked. However, Northwestern Polytechnical University is an exception. They have developed advanced airborne radar, and the related technologies may be used on the KJ-1 airborne early warning and control system.
Qin Liang was taken aback. What? This project hasn't been cancelled yet?
In 1969, the Air Force, led by the 36th Air Division, with the 603 Institute as the main design unit, the Sixth Academy as the main body, and the First Air Institute, the Second Air Institute, and the Twelfth Air Factory as auxiliary units, selected a group of elite personnel to form a design team of 150 people to develop the KJ-1 early warning aircraft.

The KJ-1 was not originally intended to be an airborne command post. Rather, it was designed to address the significant vulnerabilities in the nation's air defense, which allowed the enemy to send aircraft over frequently. The purpose of the KJ-1 was to fill the gaps in ground-based radar, build a comprehensive radar air defense network, and guide nighttime fighter jets in interception operations.

At the time, the largest aircraft the Air Force had was the Tu-4 bomber, also known as the Super Fortress-ski, which was a copy of the B-29.

With its rounded nose, tricycle landing gear, and four propeller engines, the overall technology was typical of the 1940s.

After the radar dome was installed on the back of the aircraft, the drag increased by 30 percent and the weight of the aircraft increased by 5 tons. Therefore, the engine was replaced with a WJ-6 turboprop engine. Because the propellers rotate in different directions, the speed of one side was simply artificially restricted to reduce the speed to keep the aircraft balanced.

Everything was done using makeshift methods, relying on a fearless spirit to cobble together the aircraft. Unfortunately, the outdated vacuum tube technology still limited the performance of the early warning aircraft, making it unable to filter out enemy aircraft from ground clutter. This was an unsolvable problem, and the project was eventually canceled.

If I remember correctly, it'll be dismounted soon, right?

Filled with curiosity, Qin Liang and his group boarded train 212 and arrived at the 36th Air Division base in western Xianyang.

A row of silver bombers gleamed in the sunlight. In a corner of the tarmac, a plane with a mushroom-shaped roof sat quietly, seemingly inconspicuous.

"Old Zhou, come here and introduce the KJ-1 to our guests!" Old Lin called out as he looked at an elderly expert getting off the plane.

After Project 926 began, Senior Lou Guoyao first served as the chief technical officer, and later, Senior Zhou Xianyao took over. At this moment, upon hearing Elder Lin's introduction, Elder Zhou frowned: "Elder Lin, our Airborne Early Warning and Control System No. 1 is a top-secret mission. You brought so many people here... including a young man. This is not in accordance with regulations!"

Project No. 1 in the sky, can it be visited by just anyone? It is precisely because it is hidden that it is not sent to the flight test institute, but is kept in the 36th Air Division for testing, since the flight test institute can't help anyway.

Qin Liang smiled and said, "Old Lin, this old comrade doesn't even give you face!"

Old Lin blushed; he had been careless!

The KJ-1 is the Air Force's top priority project, and there are strict regulations on who can and cannot see it. Old Lin did not follow the procedures and brought Qin Liang to visit, which was indeed a violation of the regulations.

Moreover, Lao Zhou's lack of courtesy stemmed from his distress.

After the project was initiated in 69, the aircraft was completed in 71. Then came a long period of test flights. In the first few years, the main focus was on airframe test flights, such as the aircraft veering off course and tail tremors. After these test flights were completed, the test flights of the airborne radar equipment began.

The H-6 bomber has a detection range of up to 300 kilometers, which is quite good. However, the ground radar echo interference has plagued the research and development team for years.

In the latter half of 1976, the Air Force began to systematically organize research on countering ground radar echoes, but they couldn't figure it out no matter what they tried. So, they turned to the sea, since the sea surface is flatter. But unexpectedly, they couldn't solve the problem of sea wave echoes either! From November 1978 to January 1979, the Air Force organized sea test flights again, but the results were still not obvious.

If these problems cannot be solved, then the KJ-1 project will have to be cancelled. Now, every R&D staff member is working day and night to find solutions. Looking at Lao Zhou's bloodshot eyes, you can tell that he hasn't gotten off the plane for several days.

Old Lin was really embarrassed to use his status to pressure him.

Or should we take Qin Liang back?

"This antenna is unusually thick. What kind of antenna is crammed inside? The Americans use flat panel antennas, the Russians use waveguide antennas, and we're not using watermelon rind antennas, are we?" Qin Liang asked again.

At this moment, Mr. Zhou, who had already turned around and was about to walk back to the plane, suddenly stopped in his tracks.

The early warning aircraft of various countries are highly classified, and you can't find any information about them in internationally published journals and magazines!

Moreover, when the KJ-1 was being developed, China's radar technology was lagging behind. Therefore, the 843 radar used for ground-based air defense was directly mounted on the aircraft. Its radar antenna was flat, like a piece of watermelon rind that had been eaten.

Originally just an altitude-measuring radar, when placed horizontally, it becomes a two-dimensional planar detection radar. For this purpose, a huge fiberglass radome was installed on the back of the KJ-1, with a diameter of seven meters and a thickness of... a full two meters at its thickest point in the center and one and a half meters at the edges!

With the radar radome rotating, the watermelon-shaped radar can search the surrounding 360-degree airspace. As a result, ground radar was moved into the sky. Although the search range was good, unfortunately, ground clutter could not be filtered out, making it practically unsolvable!

"How did you know? Elder Lin, did you tell him?" Elder Zhou's face darkened further. "Elder Lin, this is a serious violation of confidentiality regulations. Our KJ-1 is currently the most advanced early warning radar in the country..."

"I didn't!" Old Lin quickly shook his head.

Qin Liang chuckled: "It really is like a watermelon rind, so outdated. Even welding waveguides on would be more advanced. By the way, since it's an early warning aircraft, it has to solve the problem of ground clutter interference, right? What technology did you use to solve it?"

The Russians can't manufacture planar slotted radar antennas, but they have a secret weapon: they simply take the waveguides used on warships and put them on airplanes! Just like planar slotted radar, they create slots in a metal tube called a waveguide, achieving the same effect, only... it's a bit bigger and heavier.

Why bring up something you shouldn't talk about! Old Zhou's face was so gloomy it looked like it was about to drip water. Was he here to deliberately mock us?
"The technology behind this is all classified; you have no right to know!"

"Oh, never mind then. I was actually hoping to discuss MTI and MTD technologies with you. Let's go back!"

What?
Old Zhou was stunned for a moment: "You understand MTI and MTD?"

"Well, it seems you're already using it. I won't presume to teach you anything. This plane is classified, and it's not convenient for us to handle. Let's go, everyone!"

　PS: The 843 radar and the KJ-1 are basically radar antennas with the watermelon rind-shaped antenna rotated 90 degrees and inserted horizontally into the mushroom-shaped plate. I couldn't find a diagram of their internal structure.

　　
　
(End of this chapter)