Chapter 687 Save money! Save money!
With this performance, even if its smoke covers my position completely, I would still praise it for its good cover!
The joys and sorrows of different people are indeed not the same. I am working hard for basic performance, while others are only concerned with trivial matters.

This type of propellant is not a smokeless propellant, but a typical one that has aluminum powder added as a metal combustion agent in order to achieve low price and long range. The amount of particulate matter after combustion is extremely high.

At a certain period of time, it was not that we did not want to use smokeless propellants or did not have smokeless propellants, but the general double-base propellants were not as powerful and sufficient as the smoked ones. For the sake of that performance which was not actually very necessary, giving up the low price and high charge, anyone would choose it.

In fact, the early propellants of Rattler, Sparrow, etc. also produced smoke all the way.

Having said that, even in the 21st century, there is still no place for smokeless propellants on rockets. The main reason why air-to-air missiles need to be smokeless is to minimize the impact on the operation of fighter engines, not for the sake of appearance.

Therefore, the defect mentioned by Gao Zhendong was not a problem at all in the eyes of comrades in Fenglei Factory and others.

"Chief Engineer Gao, this is not a defect. There will always be smoke when something is burning." A comrade from the Fenglei Factory laughed.

Gao Zhendong said, "Well, what I mean is that it's best not to use this thing for air-to-air missiles, but rocket launchers can use it casually. Strictly speaking, this is not the limit of this propellant, but for rockets, the maximum burning rate is too high, which is not conducive to the range. I lowered the burning rate and affected the specific impulse a little. In addition, there is another problem with this propellant, that is, the combustion temperature is higher than the propellant you are using now, so pay attention to this problem in the design."

Adding a metal combustion agent naturally increases the combustion temperature. Anyone who has studied chemistry knows that there is a very famous combustion agent called thermite.

After listening to Gao Zhendong's words, the comrades at Fenglei Factory did not take the defects Gao Zhendong pointed out to heart, but admired Gao Zhendong very much.

While we were still groping in the dark, he was already able to make free adjustments for the necessary performance.

"Chief Engineer Gao, we will pay attention to this problem, and we have some experience." The comrades of Fenglei Factory are very clear about the pros and cons. However, this disadvantage is something that can be solved as long as we know it. Compared with the problem of not being able to rush up, it is a small matter.

After Gao Zhendong said this, he turned and looked at the comrades from the Land Equipment Bureau.

"If the propellant of 107 is similar to that of 130, then you can consider switching to this propellant. If that's the case, I'll be able to deliver on your request if the range of 107 is increased by 30%."

Gao Zhendong made a joke while talking, but in fact he knew very well that there would be no difference between the current propellants 107 and 130.

What’s even funny is that all the rocket launchers planned at that time, not to mention the plans and propellants, ultimately had quite consistent ranges.

107mm, 8.5km.

130mm, 10km.

180mm, hey, it’s still 10 kilometers, it’s really hard to stretch it.

It can be seen from this incident that any knowledge Gao Zhendong knows is extremely valuable to the comrades who are currently engaged in rocket launchers.

Comrades from the Land Construction Bureau did not expect that Gao Zhendong would not leave the problem overnight. They wanted 30%, right? Solve it immediately!
Everyone has the mentality of wanting more after getting something, and the comrades from the Land Equipment Bureau are no exception: "Then if you add your other technologies, can it be improved by 50%?"

Gao Zhendong thought about it and shook his head: "For 107, I don't really recommend using the technology I mentioned later. This technology will increase some costs. From the original design intention of 107, it is a bit contradictory. 107 is extremely simple and extremely cheap, suitable for guerrilla warfare."

The 107 was designed with this goal in mind. To some extent, the tactical mission of the 130 rocket launcher when it was first designed was not original to us, but the 107 rocket was.

To be honest, if I hadn't fought guerrilla warfare for decades and had a lot of relevant practical experience, I would never have thought of such a slightly crazy weapon as the 107 fire.

"Not higher than the neck, so it is easy to raise your head; not lower than the hips, so it is easy to step; not wider than the shoulders, so it is easy to pass; the center of gravity is close to the body to prevent twisting of the waist." These 107 words perfectly summarize the design essence of .

So Gao Zhendong thought it was okay to change the propellant, but he felt that more complicated processes were unnecessary.

However, for the comrades in the Land Equipment Bureau, this matter is obviously "I don't care what you think, I only care what I think."

"Yes, we will fully consider your opinion." This is very interesting.

Gao Zhendong didn't care. It would be best for them to decide on such matters.

"Well, whether it's useful or not, let me explain it first. You can use a dual-thrust engine. Of course, you don't need a very complicated dual-thrust configuration on the rocket. As long as it meets the standards and can be used, it's fine."

The comrades at Fenglei Factory had never heard of this: "Dual thrust? How to do it? What are the benefits?"

It is really hard to keep up with Chief Engineer Gao’s ideas, they are all new things.

Well, let's start from the beginning. "From Newtonian mechanics, we know that to change the state of motion of an object, extra work needs to be done, while maintaining the state of motion of an object is much easier, right? Based on this theory, we can infer that when a rocket is first launched, it needs a large thrust to make it move, accelerate to a certain speed, and then maintain this state, so it doesn't need such a large thrust, right?"

Everyone understands this, or in other words, all middle school students understand it, but whether one can make good use of this principle is another matter.

"That's the principle. High thrust for quick combustion to start, low thrust for slow combustion to maintain..."

"This is the principle of a multi-stage rocket. How can it be achieved in a single-stage engine?"

"Let's not worry about the realization for now, it is theoretically feasible. In this way, the working conditions of the rocket engine can be differentiated, and targeted designs can be made for different flight stages of the missile body."

"Such a simple truth, which we learned in middle school, how come we just can't think of it!"

"It's no use thinking about it, you have to be able to do it. Rockets are single-stage, and we don't even think about it in this direction."

"..."

The comrades at Fenglei Factory suddenly had ideas, and they started a heated discussion while taking notes.

Comrades from the Defense Work Committee and the Land Equipment Bureau couldn't help but twitch their faces when they saw this scene. Was Chief Engineer Gao opening the door to a new world for them?
And it sounds like this door is just a layer of window paper and is not solid at all.

But no one expected this before!
There are many times when once you break through the theory, you will find that it is actually very simple, but the difficulty lies in breaking through the window paper of the theory.

"Chief Engineer Gao, how do we achieve this dual thrust? A two-stage rocket?"

In fact, if we do not consider how many stages a rocket has, but instead regard the rocket as a whole, then the multi-stage rocket is actually a typical engineering implementation of multi-stage thrust.

But this thing obviously cannot use a multi-stage rocket, otherwise the comrades who are engaged in rockets would not be so ignorant of the principles of multi-stage rockets. The biggest reason is that they have never thought of making a temple in the screw shell of a single-stage rocket engine.

Single-stage rocket, I understand, multi-stage thrust, also clear.

Single-stage rocket + multi-stage thrust? What is this? I have never thought about it.

Gao Zhendong smiled and shook his head: "Definitely not. Using a multi-stage rocket on this thing is like turning tofu into meat, haha. A single-stage rocket has two-stage grains. The two-stage grains can be made of the same propellant or two different propellants. In order to save the most money, you can even use the new propellant I gave you for starting and the old propellant for maintenance. In fact, the effect is not bad."

When the comrades from Fenglei Factory heard this, they couldn't help but sigh at Chief Engineer Gao's unique and ever-changing ideas. What's more, these ideas are useful and have the potential to be realized.

The comrades of the Land Construction Bureau are deeply distressed. This is a wrong path! We must not do this!

Chief Engineer Gao is good in every way, except for his bad point that he tries his best to save money wherever possible.

"Comrades, let's not talk about saving money for now. How do we actually achieve this dual thrust?" The comrades from the Land Equipment Bureau changed the subject, temporarily stopping the comrades from the Fenglei Factory from going further and further down the "wrong" path.

Gao Zhendong smiled and said, "No matter what kind of propellant is used, the take-off propellant must have a larger combustion area, but it must also ensure stable combustion and be as easy to process as possible. So my suggestion is that the take-off propellant adopts a star-shaped combustion surface and an internal combustion design, and the maintenance stage adopts your current circular combustion surface, which is also internal combustion."

The internal combustion here is different from the internal combustion of a car engine. It refers to the combustion starting from the center of the propellant column and moving outward. The circle and star shape here refer to the shape of the hollow interior of the propellant column's cross section, which determines the initial combustion area when the engine is ignited.

The larger the burning area, the greater the thrust. This is why the propellant for rifle bullets is made into individual pellets or pieces.

Among them, the circular internal combustion is the simplest and cheapest, but its starting performance is poor, and the combustion area at the beginning is the smallest.

The star-shaped combustion surface is different. It can maximize the combustion area from the beginning, and equal area combustion or even reduced area combustion is possible.

Thanks to Gao Zhendong's illustrated explanation, the comrades at Fenglei Factory have mastered the technology and have also expanded on it based on their own professional knowledge.

"Chief Engineer Gao, since starting thrust is so important, why don't you make the starting section internally and externally combusted? That way the starting thrust will be greater."

Well, this comrade understood.

"The main thing is that the star-shaped combustion surface is sufficient. Increasing it is not only meaningless, but will also bring new problems. In the case of internal combustion, the shell will not be burned until the end of the combustion, and the high-temperature performance requirements for the shell are much lower. However, internal and external combustion will directly burn the engine shell from the beginning, which will bring great challenges to the high-temperature performance of the shell and will cause many other problems."

(End of this chapter)