Chapter 254 Air Police 200, wedge tail antenna

Although what Liang Shaoxiu said was not wrong, Chang Haonan never expected this plot development.

It seems that due to word-of-mouth spread among aviation industry insiders, the speed and scope of his fame are beyond imagination.

This is also a good thing. The higher his reputation, the easier it will be to achieve the goal he set at the beginning of his rebirth.

Moreover, as a normal person, Chang Haonan's mood naturally improved a lot after hearing others make such comments about himself.

As for Wang Xiaomo’s problem...

For him, it wasn't even a problem.

After all, the Air Police 200 in the previous life was designed on the basis of the Y8 III platform.

Now, after a round of additional improvements, the Y-8F-400's performance in all aspects, especially safety and low-speed maneuverability, far exceeds the former. Naturally, it is more suitable as a special aircraft platform including early warning aircraft.

Of course, if the plan that Chang Haonan designed with Ding Gaoheng can be completed normally, then after entering the new century, China should be able to complete the design improvement and localization of the Tu 204/214 passenger aircraft, and by then there will be no need The veteran of Yun 8 continues to take the lead.

Therefore, there should not be as many models using Category 3 platforms in the end as in previous generations.

But these are all things for later. For now, we can only consider building a dojo inside the snail shell of Yun 8.

From the perspective of hindsight, the design of the Air Police 200 is not perfect, and there are still many areas that can be improved.

And this just leaves room for Chang Haonan, who is not satisfied with simply replicating previous designs, to play.

The only thing he needs to determine is the current level of China's radar technology.

The electronics industry is already developing at a fast pace. Just because the 2002th Institute of Electrical Engineering in 14 was able to build an early warning aircraft radar does not mean that the 1997th Institute of Electrical Engineering in 14 could also do it.

Therefore, after a brief hesitation, Chang Haonan still did not take over everything and chose a relatively cautious response:

"Although I am very grateful to Liang Gong and Academician Wang for your trust in me, I definitely need some more detailed information before I can make a judgment on this matter."

“After all, the core of developing early warning aircraft is radar. The Y-8 platform does have considerable modification potential from a structural and aerodynamic perspective, but whether it can be implemented depends on whether the Electronic Technology Group can come up with a sufficiently compact radar. "

Having said this, he paused for a moment and then added an example:

"For example, a disc-shaped radome with a diameter of more than ten meters like the ring project you just mentioned cannot be installed on the Yun-8. It is too big."

Although he did not receive any direct guarantee, Wang Xiaomo still sensed a very positive meaning from Chang Haonan's tone and attitude.

It shows that the feasibility of changing the early warning aircraft is actually very high in the latter's mind.

It's just that the engineers' instinctive rigor prevented them from giving a direct conclusion.

This made Chang Haonan's evaluation in Wang Xiaomo's heart even higher——

After all, he is an academician of the Electronic Science and Technology Group, and he has not intuitively felt the other party's abilities like Du Yishan and others.

Although he had Liang Shaoxiu's endorsement, after meeting him today, the young academician still felt a little guilty about the young man in front of him.

Engaging in engineering is different from theoretical research. On the one hand, it requires experience, and on the other hand, it also requires a calm mind.

Both of these often need to grow slowly over time.

A bit similar to doctors and teachers, an image that is too young always makes people feel unreliable at first.

Now, Chang Haonan has at least proven that he has no shortcomings in the latter aspect.

This is how trust is built step by step.

"This is what I think about the design of radar antennas."

Wang Xiaomo took out a few pieces of paper from the briefcase he carried with him, obviously prepared:

"Based on our current technical level, in order to ensure that the radar has a detection range of about 5 kilometers for targets with an RCS of 300 square meters, about 2000 T/R components are needed. Uh... Xiao Chang, you should know What is a T/R component?"

Seeing Chang Haonan nodding, he continued:

"Combined with the packaging process, if you want to arrange these two thousand T/R components on an array, the size must be 8.5*0.6m. In this case, as you just said, the disc radome and The three-sided array structure will definitely not work.”

Having said this, Wang Xiaomo turned over the calculation of the antenna size on the first page, revealing the overall plan concept on the second page.

As expected, it was exactly what Chang Haonan was familiar with.

But he still had to pretend to be slightly surprised:

"Balance beam antenna?"

"Yes, in fact, the Saab 340 early warning aircraft that the Swedes first flew two years ago already used such a structure. Although there are 60° blind spots directly in front and behind the aircraft, the antenna can be installed vertically on the aircraft. The entire antenna structure The weight can also be reduced to less than 1 ton, which should be more convenient for your aircraft design department."

"If an 8-and-a-half-meter antenna is installed like this, it should be acceptable."

Seeing that the heat was almost there, Chang Haonan was ready to reveal the more complete plan:

"But I have a slightly different idea."

Sure enough, Wang Xiaomo showed an interesting expression:

"Tell me."

"Actually, I also paid attention to some Saab 340 situations at the time, so I did some calculations in my spare time."

Chang Haonan picked up a pen from the side, and at the same time Guo Lin also placed a piece of paper in front of him.

Pass the paper to the boss.jpg

There is no such thing as paying attention to the Saab 340AEW. This model first flew in 1994. At that time, Chang Haonan had not yet been reborn. He was just a sophomore who worked hard but had average talent.

It's just that this kind of thing is obviously what he said.

"First of all, even in terms of balance beam design, Saab's solution is terrible. They chose a radar cabin bracket solution that has the greatest adverse impact on the aircraft."

As he spoke, Chang Haonan drew several different radar installation methods on the paper with a large stroke of his pen.

"The directional stability derivative of the plan A bracket selected by Saab 340AEW is positive and has an unstable effect, but this situation will not occur in the other three plans."

"But the point I want to say is not this, but this type of balance beam antenna. No matter how it is designed, it cannot avoid the bracket causing side wash at the vertical tail, interfering with the direction of the vertical tail flow, and at the same time, the blocking effect of the bracket is reduced. Considering the incoming flow speed on the vertical fin, it can be said that the damage caused by this bracket to the directional stability is even greater than that of the radar antenna itself."

"Is that really the case?"

For people who are not majoring in aviation, this conclusion does sound a bit counter-intuitive at first, but the problem of aerodynamics is like this, and some inconspicuous small places matter a lot.

"Yes."

Chang Haonan nodded, and the movements of drawing lines on his hand were also very fast:

"To make up for this loss of stability, we not only need to design two large ventral fins on the tail, but also consider raising the vertical tail part. If it is a large aircraft like the IL-76, that's it, but the Y-8 has the largest The take-off weight is only 60 tons. After modification, it will have a great impact on the structure, and further adjustments to the airframe will be required. This workload will be too large."

"So we might as well open up our minds and simply get rid of this obstructive bracket, connect the radar array directly to the fuselage, and let the antenna itself serve as a supporting structure. This way, the impact on directional stability and the resistance it brings will be smaller. Moreover, a larger array area can be obtained. In addition, a 'hat'-like structure can be added on top of the side-view antenna to install two antenna arrays in the front and rear directions. Although the performance is definitely not comparable to that of the side view, at least it can be considered achievable. 360° full coverage.”

"Although this will still have some impact, it can be offset by adding two ventral fins, and there is almost no need to make major modifications to the overall structure of the aircraft."

Practice makes perfect when it comes to painting, because during this period he often used similar methods to present plans, so the things he painted now were at least less abstract.

At least Wang Xiaomo can understand it at a glance.

In fact, the plan proposed by Chang Haonan is basically the "wedge tail" antenna of the previous American E737 early warning aircraft. It can be regarded as a comprehensive upgrade of the traditional balance beam plan.

The only disadvantage is that the weight of the wedge tail structure is much greater than that of the balance beam, so it cannot be installed on a platform that is too small.

However, perhaps the only advantage of Yun-8 as a special aircraft platform is that it has a large load capacity.

The Boeing 737 has a load capacity of 16 tons, and the Y-8 can carry 20 tons.

A few hundred kilograms more is not a problem at all.

In short, if the Air Police 200 can use this design in advance, it will definitely bring huge performance improvements.

Good news for pilots, too.

You know, early warning aircraft are generally not easy to fly.