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

Chapter 140 The missile engine's performance is too poor and needs to be improved!
During the Vietnam War, the performance of air-to-air missiles was still unstable, and Phantom fighter pilots often fired all their missiles at once, hoping to increase their hit rate.

The emergence of the Skyflash missile finally solved the reliability problem. Its world's first single-pulse semi-active radar seeker has better anti-electronic interference capabilities and guidance accuracy than the previous conical scanning seeker. The maximum rotation speed of the seeker antenna has reached 230 degrees per second, which is faster than the antenna rotation speed of many airborne radars!

This allows for a maximum tracking angular velocity of 40 degrees per second, easily keeping up with enemy aircraft and ensuring a high hit rate.

Although Qin Liang had a whole host of more advanced seeker technologies in his mind, if the electronics industry technology couldn't keep up, it would all be for nothing. At present, imitating Marconi's seeker is the best option in the East. Moreover, if it is handed over to Northwestern Polytechnical University, they are fully confident that they can replicate it. This is not a problem.

The key is the projectile itself!

At that time, solid propellant technology was still very primitive. This Skyflash missile used the Mk38 Mod4 solid rocket motor from the Sparrow missile, weighing a total of 65.5 kg and containing 42.73 kg of propellant. And yet, it only had a maximum head-on range of a mere 29 km! Even less than the original Sparrow!
Moreover, this head-on range figure is highly inflated. When our side launches a missile, the enemy is also flying towards us. The two sides flying together across the maximum range of 29 kilometers is essentially the enemy deliberately colliding with us!
When there is a head-on collision, there is a tail-chasing collision. At this time, the opponent is flying in front of the missile, and the missile has to fly a much greater distance to hit the target. This will rapidly reduce the range, even to within ten kilometers!

This is hardly a medium-range missile! In later generations, even a short-range missile would have a maximum range of over forty kilometers!
The range is too short; it needs to be changed!
"Comrade Qin Liang, if we want to increase the range without changing the propellant technology, we need to use more propellant. But if we use more, the missile will be heavier, and it will consume even more propellant..."

This is a classic case of adding too much water to the flour and too much flour to the water!
Even the Phoenix missile, with its maximum range of over 100 kilometers, is enough to make it stand out in this era. That's because after it takes off, it soars to an altitude of 28,000 or even 32,000 meters where the air is thin and the resistance is low. If it were to fly directly, its maximum range would only be about 40 kilometers, which is no different from that of a sparrow!

“Yes, unless it is launched into the high altitude first, but... the semi-active radar guidance system is destined to be unable to leave the guidance beam of the airborne radar…” Another engineer from Institute 612 spoke up.

In a semi-active guidance system, the missile's seeker can only receive radar waves, requiring the carrier aircraft to provide radar illumination. The Phoenix missile, however, uses an active radar seeker to reach high altitudes. Once its own radar provides target information, it can handle the rest.
"Yes, reducing drag is one way to increase range, so... could we clip the tips of these wings? This would reduce the wingspan and thus lower air resistance..."

Upon hearing Qin Liang's words, the air-to-air missile experts present all shook their heads repeatedly.

"Of course not! Missiles have many specifications, not just range, but also maneuverability. Reducing the wingspan can lower air resistance, but it will reduce maneuverability!"

"Yes, with a smaller wingspan, the torque on the control surfaces is smaller, and the control laws for adjusting the missile's flight attitude must also be changed accordingly. With our technological capabilities, that's very difficult!"

Qin Liang smiled and said, "Adjusting the control law in digital circuits isn't difficult. As for the maneuverability requirements... we'll have to modify the engine. Have you ever heard of a dual-pulse engine?"

Overload is a very important indicator for measuring the maneuverability of an aircraft. Advanced third-generation fighter jets generally have an overload of 9G. The aircraft are very agile and often pull the pilot out of red and black. Missiles do not require a pilot and do not need to consider the limits of the human body, so they generally have an overload of 30G or more.

However… this overload isn't achievable throughout the entire flight. In the initial phase after launch, the rocket engine is still propelling the missile, providing strong overload capacity. But as it enters the inertial flight phase, air resistance causes the missile's speed to decrease, the control surface torque to diminish, and its maneuverability to deteriorate. In the end, forget 30G, it might not even reach 10G.

Therefore, a fighter jet with a 9G overload outrunning a missile with a 30G overload isn't something only seen in farcical TV dramas. "Dual pulse? What does that mean?"

"Inside the missile engine, we use a flame-retardant and heat-insulating layer to divide the engine into several sections, each with an independent ignition device. This way, after the missile flies out, it is no longer a process of acceleration and deceleration, but multiple ignitions, especially in the final distance to the target, where the engine is reignited, allowing the missile to intercept the target with maximum maneuverability!"

A double pulse isn't just two segments; it can have many segments!
Previously, missiles would accelerate forward after ignition, but once the fuel was exhausted, they would enter inertial flight and gradually slow down...

The dual-pulse technology involves igniting a phase first, accelerating forward, then extinguishing the flame. The missile continues its inertial flight for a period of time, and once its speed decreases to a certain level, it ignites a second phase to accelerate... In particular, the final ignition before reaching the target ensures that the missile is in the best possible condition to meet the opponent!
Later long-range air-to-air missiles resembled medium-range missiles in appearance, but their range increased dramatically thanks to this unique dual-pulse technology! Even now, with domestic solid-propellant technology not being up to par, this method can still extend missile range to sixty kilometers!

Everyone was shocked.

This idea is so far-fetched!

"Impossible, impossible! The internal temperature of a rocket engine is extremely high. What kind of flame-retardant layer could prevent heat from being transferred to the rear?"

"Yes, multiple ignitions greatly increase the complexity of the system. If one of them fails to ignite, the missile's range will be significantly reduced, leading to an attack failure."

A group of experts began to shake their heads.

"Engineer Dong, what do you think?"

Engineer Dong took a deep breath: "We're getting old, our thinking has become rigid. The future belongs to you young people!"

As expected, Dong Gong, as the chief R&D engineer of the project, has a truly different perspective!
Professor Lin nodded: "Alright, in that case, this dual-pulse rocket engine will also be developed by your Northwestern Polytechnical University! Our Air Force has already approved three million yuan in research and development funding, all of which will be allocated to your Northwestern Polytechnical University!"

"Three million? That's not even enough to fill a tooth gap!" Qin Liang rolled his eyes at Old Lin.

"Once you've developed it, we'll set up a production plant. The production of this medium-range air-to-air missile will also be handled by the Northwestern Polytechnical University's affiliated factory!" Old Lin said.

(End of this chapter)