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

Chapter 185: That old relic is outdated and needs to be changed!
Beside him, Old Lin smiled and said, "Old Zhou, the people I brought this time are the developers of our first domestically produced airborne pulse-Doppler radar! Especially this student Qin Liang, who single-handedly promoted several domestic research and development projects. If you don't want them to have access to classified information, then forget it!"

Old Zhou opened his eyes wide.

Pulse Doppler radar! The primary function of this type of radar is to detect targets amidst ground clutter! This is precisely what the KJ-1 airborne early warning and control system urgently needs!
"Qin Liang, wait a moment!" Old Zhou looked at Qin Liang, who was turning his head away: "On behalf of Project 926, I welcome you to visit our KJ-1 early warning aircraft!"

Anyway, since the person was brought by Elder Lin, if things really come to a head later, Elder Lin will have to take the primary responsibility!

"Alright, let's take a look at this old antique."

Upon hearing Qin Liang's words, Old Zhou's expression became complicated. An old relic? Our most advanced KJ-1 early warning aircraft in the country is considered an old relic by this young man?
Behind Zhou Lao, engineer Xiang Zhongkai, who came out of the cockpit, said unhappily, "Hey, what do you mean by that? Although the KJ-1 project has been in place for ten years, it is not an old relic. It is the most advanced early warning aircraft in our country!"

"Oh, why is our advanced early warning aircraft using the Tu-4 bomber platform? Isn't that World War II-era airframe considered an antique?"

For a moment, everyone was speechless.

The Tu-4 is a copy of the B-29, a platform indeed developed during World War II! Despite some improvements, it cannot conceal its outdated nature, but…

"Qin Liang, you're right, this airframe platform is indeed a bit outdated, but... there's nothing we can do about it. When civilian airliners are introduced, their military applications are restricted. In our military, this Tu-4 bomber is already the largest..."

"Yes, that was true before, but now we have the Y-10! We can modify it on the Y-10 platform. The Americans' E-3 early warning aircraft is also modified on the Boeing 707 platform. Our Y-10 is in the same class as the Boeing 707, making it the most suitable aircraft for modification into an early warning aircraft!"

"The Y-10?" Old Zhou shook his head: "The Y-10 won't do. Let's not even talk about the problems with the fuselage beam. Just take the engine for example. Our domestically produced WS-8 turbofan engine is too poor in performance. Currently, we can only use the JT3D engine that is a backup for civil aviation, with a thrust of only eight tons. It's barely enough to propel the Y-10. If we want to modify it into an early warning aircraft, the drag will increase by at least 20%, which requires a more powerful engine. The American E-3 also replaced its engine with Pratt & Whitney's TF33, which increased the thrust to 9.5 tons..."

If the Y-10 is to be modified, it will probably have to use the WP-8 turbojet engine from the H-6 bomber. However, this engine has a very short lifespan and requires major overhaul after only 800 hours!

"The engine is not a problem. Our domestic 430 factory has already improved the Spey engine to ten tons of thrust, which is more powerful than the E-3 engine. If that's not enough, we can further improve it. I dare not say more, but increasing it to twelve tons is no problem!"

Old Zhou's eyes widened: "What did you say? A Spey with ten tons of thrust?"

"Yeah, it's basically just replacing the fan with a bigger one, increasing the bypass ratio to 2.4. Northwestern Polytechnical University helped with the design, and it's already being used to improve the H-6 and Y-10 bombers." Qin Liang sighed helplessly. These people were completely unaware of what was happening outside. He glanced at the plane again: "This old relic really can be retired!"

Xiang Zhongkai nodded with a complicated expression: "Yes, it's really an old relic. If we could use the Y-10... it would actually be a pretty good solution."

Western early warning aircraft, electronic warfare aircraft, and so on are all modified from passenger planes. The biggest advantage is that passenger planes have fully enclosed pressurized cabins. Modifying them provides crew members with a lot of space to move around, and even allows for the installation of several sleeper berths for crew members to take turns, thus increasing loiter time.

However, this requires having your own passenger plane. If you don't, you can only modify bombers or transport planes. Pressurized cabins need to be installed separately, so the space won't be very large, the interior will be very cramped, and the noise will be very loud!
Old Zhou nodded: "Let's go up and take a look. Give us your opinions on the MTI and MTD you just mentioned, and see if they can be installed on our early warning aircraft!" Modifying the platform is no small matter! It involves writing reports and applications, and there's a long approval process. Right now, let's solve the biggest problem with the KJ-1 first!

“Okay, let’s go up and take a look. These technologies aren’t actually that complicated. Take MTI for example, using a delay line canceller, you can remove stationary targets and slow clutter while retaining information about moving targets…”

MTI is an abbreviation for Moving Target Indicator, which is a technology for displaying moving targets.
"Qin Liang, tell us in detail?" Xiang Zhongkai came up enthusiastically, putting his arm around Qin Liang's shoulder, acting as if they were brothers.

"In continuous wave radar, most of the clutter is concentrated near the zero frequency band, while for pulse radar, a very deep stopband is needed at integer multiples of DC and PRF... Wait, all of your devices are actually made of vacuum tubes?"

As they talked, they walked inside. Now, Qin Liang had seen the disassembled electronic equipment. Looking at the light bulbs inside, he couldn't help but shake his head.

Even if this early warning aircraft was developed ten years ago, you should at least use transistor circuits, right? When it's in the air and there's turbulence, the filaments in the vacuum tubes can easily break!

"What's wrong with vacuum tubes? Vacuum tubes have high power and are not easily affected by interference..." An engineer who was testing the circuit said without looking up, "Back when the Dongfanghong satellite was launched, our signal could be received all over the world. That's the advantage of vacuum tubes!"

Qin Liang shook his head helplessly, then turned around and said, "Old Lin, let's go!"

go?
Old Zhou was taken aback: "Qin Liang, you just said you'd help us solve the noise filtering problem, and now..."

"I never imagined our equipment would be so outdated. Moreover, our R&D personnel are sticking to old ways and clinging to outdated methods. I have no confidence in modifying this early warning aircraft anymore. Forget it, let's just go back!"

The engineer on the ground stood up: "Staying true to the old ways, clinging to outdated methods? Do you think we're all relicts of the past? Of course we know about the West's advancements! Their radar antennas use flat panel slots, and for post-processing, they use digital computers. That technology is advanced, but... we don't have it!"

"Who said we don't have any?"

Where did we get it?

"Northwestern Polytechnical University! We've even started making radar antennas for the British! The planar slotted antenna is just a thin layer of paper; once you break through it, everyone understands. In terms of post-processing circuits, Northwestern Polytechnical University also has advanced microcomputers. Our own pulse-Doppler radar is a digital system! This radar has already completed most of the testing tasks and will soon be officially finalized!"

Seeing the surprised looks on their faces, Qin Liang was speechless. This was a classified project? It was kept secret from everyone, even the outside world?

(End of this chapter)