Chapter 618 Let’s engage in PD
Everyone wants good things. This is normal. We cannot afford to build big ships. We are still on the road to "air-to-submarine and fast", and this bomb solves the problem of "empty" and "fast" in one fell swoop. The problem is that both of these products have strict requirements on the size and weight of the projectile.
Gao Zhendong himself knows nothing about this matter. He is currently receiving Mr. Liu who is engaged in the landing work of the "615" fighter radar.
The 615 radar is now prepared for the G-5 multi-purpose fighter. Its goal is to maximize the use of the pointed nose of the multi-purpose fighter.
Regarding the size of the radar, Mr. Liu had already obtained the data from the Cidu Aircraft Factory through the National Defense Work Committee.
As soon as he got the data, Mr. Liu felt lucky that he had decisively escaped from the RP-1 "Emerald" radar imitation.
Compared with the tight RP-1, this space size is too generous, and there is no antenna in the middle of the air intake, so the problem of interference from the air intake lip must be considered.
Similarly, the weight index has also been relaxed a lot. This is due to the improvement of lift-drag ratio and other related indicators after the G-5 multi-purpose model adopted Gao Zhendong's many suggestions.
This is what you make your own, and it gives you a great sense of accomplishment. Imitation of RP-1 is really not a pleasant job. Even if the imitation is successful, the radar will only be able to solve the problem.
Thinking of this, Mr. Liu felt a little sorry for the original deputy chief engineer who worked on the RP-1 imitation work. He is now the chief engineer. Comrade, thank you for your hard work. I will treat you to dinner when I go back to the unit.
But that can't be said about this. For the original deputy chief engineer, it's just a little hard work. Who doesn't work hard these days? People have to do the work. It seems worth it to be replaced by a chief engineer.
Now, Mr. Liu is in Gao Zhendong's office, discussing with Gao Zhendong with the plan he has already thought of.
Generally speaking, the plan has reached the extreme level that Mr. Liu can master now.
The plan does not use monopulse radar. The disadvantage of monopulse radar is that while obtaining the target distance, it can also obtain the radial movement speed of the target relative to itself, but it cannot obtain its horizontal movement component. In this way, the movement of the target is unknown. Status control is incomplete, which will cause certain problems in fighter fire control.
The shortcoming of continuous wave radar is that it is difficult to distinguish the before and after relationships of continuous signal echoes, resulting in the ranging distance being greatly compressed.
Therefore, the solution chosen by Mr. Liu is a continuous frequency modulated continuous wave radar, which can solve the problems of ordinary continuous waves through frequency changes of continuous modulation, thus greatly extending its ranging range.
At the same time, another advantage of this kind of radar is that it uses continuous wave scanning to calculate the true motion state of the target through different velocity components at two scanning angles during the scanning process.
This solution has nothing to do with digital signal processing, but is a simple calculation after obtaining the two states before and after, so there is no requirement for digital signal processing technology.
However, this thing is not without its flaws. In addition to not introducing Doppler technology, which leads to an increase in the error in calculating the speed of high-speed targets, the most fundamental problem is still the continuous wave.
Under the current environment, in order to ensure that radar self-interference does not occur, the transmitting power of this thing cannot be increased!
Moreover, since the energy of the continuous wave is equally divided, the energy density of the same power is not as high as that of the pulse signal, and the actual signal-to-noise ratio is still not high.
Before the maturity of active phased arrays, PD (pulse Doppler) radar dominated high-performance fighter radars for several decades, and it is not without reason.
Looking at the overall structure of the radar, Gao Zhendong frowned.
Mr. Liu was very keen: "General Engineer Gao, is there a problem with the plan?"
He now has a rough idea of Gao Zhendong's style. Chief Engineer Gao has his own logic of judgment, which makes him appear to others to be extremely radical at times and very conservative at other times. However, his way of judgment is difficult for others to grasp. Pulsating.
However, looking at the final result, he still made sense every time. All I can say is that extraordinary people do extraordinary things.
"General Engineer Gao, this plan may be a bit radical, but I estimate that it is still possible to implement. In addition, in order to ensure the downward viewing capability, we plan to add a single pulse mode to this radar. Using the single pulse mode, use The moving target designation technology you proposed solves the problem of radar looking down.”
I only talk about looking down, but I won’t talk about shooting down. There is still a little distance from looking down to shooting down. I looked down and saw it, and rushed over to use the cannon.
Gao Zhendong woke up from his meditation and shook his head: "Radical? No, no, this radar is not radical. I'll look at it again, I'll look at it again."
I'll tell you in a moment what true radicalism is.
"Oh, okay, keep reading, and if you have anything to explain, just ask it."
"The detection distance of the F-100 Saber is not less than 40 kilometers, and the tracking distance is not less than 20 kilometers. Is this proposed by the Air Force?"
Mr. Liu smiled: "No, no, this is what we proposed. It hasn't been formally submitted yet. Let's mention it like this first. This distance is already more than double that of RP-1. I don't think the Air Force will do it." Any comments? "The detection range of the RP-1 radar is only a dozen kilometers, and the range measurement distance is only a pitiful few kilometers. This is the biggest reason why Gao Zhendong has no interest in imitating this radar.
If visibility is not taken into consideration, this piece of shit is not as useful as eyes. But having a pair of eyes costs nothing, but carrying a radar weighs several hundred pounds.
"Hmm... It's a little small, it's a little small." Gao Zhendong's thoughts were actually much higher than this.
"Small? Mr. Gao, this is already a very optimistic and radical idea." Mr. Liu still wants to talk about science, but it's a pity that users won't talk about science with you.
For example, the radar that was later used for 8 Masters was launched in 1966. At that time, the technology was still extremely backward. However, the Air Force had a double-three requirement from the very beginning, with a detection range of 100km, but it had not been developed for decades. .
If double three mainly depends on the aircraft, then our first-generation radar people have not been able to achieve a detection range of 100km even though they tried their best.
Gao Zhendong thought for a while and put forward his own opinion.
"Mr. Liu, my suggestion for this thing is to have an upward view of 50 and 30 meters, a downward view of no less than 30 kilometers, and the ability to provide illumination for semi-active radar bombs. Otherwise, the first one installed in the air will not be happy."
Considering that the radar antenna diameter of the G-5 multi-purpose fighter is 0.6 to 0.7 meters, it is possible to obtain this indicator after thinking about it.
The AN/APG-59 of Citigroup's F-4J is larger than this and entered service in 1966. However, the head-on detection range of the MiG-21 is about 80 kilometers and the downward-looking range is more than 60 kilometers.
These words made Mr. Liu and his entourage almost have their heads exploded. No wonder he just said that the plan was not radical. It turned out that he was the most radical one.
"Mr. Gao, is this too high? I'm afraid we are beyond our capabilities." Mr. Liu, who did not dare to consider anything above 50, decided to argue with reason, otherwise the comrades below would be under too much pressure. .
Gao Zhendong thought for a moment and realized that it would be bad to scare away the comrades who were doing the specific work. He nodded: "Let's do this. We will first report according to what you set, but our real goal is not this indicator. , at least achieve what I said.”
Originally, Gao Zhendong wanted to talk about the multi-target tracking and strike capabilities, but when he thought about it, this was really scary. If he mentioned this thing, they would probably be scared away and turn around, so it was better to let it go. When they actually realize their ideas later, they will think of it themselves.
Mr. Liu had no objection to Gao Zhendong's idea of disclosing small goals and internal big goals. This was also a commonly used "leaving one hand" approach in scientific research. It was low-pressure. It seemed that Chief Engineer Gao was still very particular about it.
"Well, I have no objection to this. You can do it this way. But the power of continuous wave radar is not high, and the requirements for signal processing are too high."
When white noise cannot be eliminated and there is no technology to obtain sufficient information under low signal-to-noise ratio, the most fundamental way to improve detection performance is to increase the transmission power and increase the signal-to-noise ratio.
"Continuous wave? If we don't do continuous wave, it will be a transitional technology. At least within a few decades, I estimate that this thing will have no future in fighter radar. We will still make pulse radar."
Gao Zhendong shook his head in disgust. Continuous wave has been equipped on fighter jets for a very short time. Only a few aircraft such as the early Sparrow radar have used this thing, such as the F-4E, which was quickly given to the PD. replaced.
"Pulse? Well, a single pulse is not impossible. Just open a branch path for the continuous irradiation of semi-active radar bombs. Others, if there is no horizontal motion component data, it is not unacceptable."
"Without monopulse, this thing's downward vision capability is limited, and it's not very good at guidance and fire control."
Mr. Liu is going crazy. This won't work, and that won't work either. So what are you going to do? You can't do a phased array, right?
"Hiss~~~~~~ Chief Engineer Gao, do you want to build a phased array?"
Different from the subconscious understanding of many people, we wanted to develop phased array system radar very early, including on fighter fire control radars, but the results were quite mediocre in the early days.
So it’s not that Mr. Liu doesn’t know about phased arrays, but he knows very well that this thing is very unreliable, at least at this stage. Whether it can be done or not is not yet said, but for that matter, I’m afraid it can’t be installed on a fighter jet. Down.
Chief Engineer Gao's move can't even be described as nonsense, it's like tearing people in half!
However, Gao Zhendong quickly solved his doubts: "Mr. Liu, let's build a pulse Doppler radar."
Pulse Doppler radar?
To Gao Zhendong's surprise, Mr. Liu was not as familiar with pulse Doppler radar as with phased arrays.
Although they are both generational methods of radar, in fact, strictly speaking, these two technologies are two definition modes.
(End of chapter)