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

Chapter 156 Joint Development of Monster 3 Missiles
"What? The maximum off-axis launch angle is only twenty degrees?" Qin Liang frowned. "This technology is terrible!"

Is that all? Old Lin, standing to the side, knew that Qin Liang was about to put on his show again!

In the early days of air-to-air missiles, the seeker head could not be moved. That is to say, the aircraft's axis and the line of sight had to be aligned in the same direction so that the missile could lock onto the target and launch an attack.

Therefore, air combat in the missile era, like air combat with machine guns, requires relentlessly pursuing the opponent's tail for several minutes to create an opportunity for missile launch. Fixed-axis acquisition and fixed-axis launch are, in practice, very difficult!
It wasn't until the third generation of air-to-air missiles that off-axis launch technology was introduced. The missile can lock onto targets as long as they are within a cone-shaped area in front of it. The size of this cone determines the missile's off-axis launch capability.

Twenty degrees, so the vertex angle of this cone is forty degrees!

This is already incredibly outrageous, and now the customer in front of me is actually saying... 20 degrees isn't enough, the technique is too poor?
Raymond was about to retort when, at that moment, engineer Daniel stepped out.

"Sir, you complain that our missiles' off-boresight launch angle is too small. Do you have a better solution?"

"What's so difficult about that?" Qin Liang said. "The off-axis launch angle is mainly determined by three factors. The first is the gimbal on the missile seeker. The more flexible the gimbal, the faster the seeker can rotate, the greater the range of motion, and the greater the angle that can be changed. So, for you, this shouldn't be a problem."

Daniel nodded: "That's right, this isn't too difficult."

"However, after the missile locks onto the target and is launched, it must keep up with the target, especially when the distance is too close. If the missile cannot turn in time after launch, it will miss the target."

Off-axis launch—launch is the key!
The other person continued nodding, their eyes sparkling: "So how do we solve this problem?"

Qin Liang smiled and said, "Add vector thrust to the missile, and use the energy of the rocket engine after launch to help the missile turn!"

Normal aircraft change direction using control surfaces, but the aerodynamic torque of these control surfaces is not very large and is subject to many limitations. The solution to this problem is vector propulsion!
"Vector propulsion? That's one approach, but how exactly do we do it?"

Qin Liang smiled and said, "It's a secret! Let's talk about the third issue. What limits your missile's off-axis launch capability is the targeting device, also known as the head-up display. Its field of view is only about 20 degrees. So, no matter how great the missile's off-axis launch capability is, it's meaningless because the pilot cannot designate the target."

"That's right, the key is the head-up display. How do we solve this problem?"

Draw two lines from the pilot's eyes to the center and edge of the head-up display. The acute angle connecting these lines is the pilot's field of view. In the era of refractive head-up displays, this was at most twenty degrees. Therefore, the off-axis launch capability of missiles could only be limited to this angle!

Qin Liang smiled calmly again: "Helmet sights."

Old Lin remained silent.

Keep bragging, kid. We don't have any of these things!

The other side has clearly taken the bait! Daniel took a deep breath: "What did you say? A helmet-mounted sight? How do you locate it? How do you let the missile know where the head is aimed? How do you lock on?"

"Secret."

"How can you tell us this? Are you selling your technology? We're willing to pay for it!" Daniel said.

They are not short of money. After all, they are the nation that makes the most money in the world. As long as there is top-notch military technology, they can buy it!

Qin Liang shook his head: "No, no, we won't buy it."

"Then what are you doing here?" Raymond asked angrily. These Asians, were they here to cause trouble? He'd heard they snatched a huge order from Dassault yesterday, and now they were showing off at their booth… "We're here to seek cooperation," Qin Liang said. "We're very interested in this air-to-air missile, especially its guidance system. We can exchange our vector thrust technology for the guidance system technology, and our helmet-mounted sight technology for other missile technologies. This way, you'll have advanced off-axis launch technology, and we'll get an advanced short-range missile. We each get what we need, how about it?"

In later generations, the East spent a huge sum of money to import the Python 3 missile; some say 200 million, others say 500 million. However, the Python 3 missile took root in the East, first leading to the PL-8, and then the smaller version, the PL-9, which remained in use until the 21st century.

So, we must import these missiles, but... we don't want to spend the money, so let's just exchange technology for technology!
"Could you let us take a look at these technologies first?" Daniel was certainly not swayed by these claims.

"No, your technology would be compromised as soon as you see it. Forgive my bluntness, but even if I saw your seeker technology, it wouldn't be of any use, since it requires an advanced production line. But with your capabilities, once you've seen our technology, you can easily replicate it yourself, so..."

"After all that talk, you've just been bragging..."

Qin Liang glanced at Raymond and smiled: "However, we can agree on the weapon interface. After your missile is developed, it can be mounted on our aircraft, and we can demonstrate the linkage capability of the helmet-mounted sight. As for the vector propulsion device, we can modify that after we have a foundation for cooperation."

"Okay, we can sign the contract now and agree on the weapon interface!"

The so-called agreement was simply to follow the Davidians' lead completely, since their weapon interfaces were the same as those of the Sidewinder missiles and could be interchanged at any time. This was considered a common feature and was not a secret within NATO.

After obtaining a large amount of data, Old Lin looked at him with a complicated expression: "You kid, you've been going through all that trouble just to trick us into revealing this weapon interface?"

"Of course not. We are sincerely seeking cooperation, otherwise it would tarnish the reputation of our Eastern military industry."

"Sincerity? Do we have what you're talking about?"

"Not now. We'll start developing it as soon as we get back. That vector propulsion is basically just four baffles, very simple. As for the helmet-mounted sight... it's just an iron ring, nothing difficult... By the way, Mr. Lin, the Air Force has to give us some funding when we get back!"

"What?"

"What? Does the Air Force want to be a penny-pincher?"

"No, no, I mean, those techniques are very simple? How come the Davids didn't think of that?"

"They're top-notch at doing business, but when it comes to technology, they're still far behind!"

"Old Lin, Qin Liang, we've finally found you!" Just then, a man came running up, panting, "Old Tu wants you to come back."

"what happened?"

"Another big customer has arrived, inquiring about our Super-7 fighter jet!"

"Who?"

"The Land of Weeping!"

　PS: The image above shows the vector thrust of the R-73, which is actually just a baffle. The image below shows the gimbal of the infrared seeker.

　　
　
(End of this chapter)