Chapter 523 The suggestion is a bit loud
So when seeing this, the comrades who were working on Attack-5 felt like fools. How could they not have thought of such an obvious problem?

"Goose egg..." Yes, this unit is the one that Gao Zhendong asked about 16mm and 8mm steel cables last time.

Fortunately, we are only conducting static tests now and have not yet reached the first flight. Not many prototypes have been built, just a few, so the loss is not too big.

It seems that the only option is to move it back to the wing root. It is unknown for what reason the cannon that was originally placed at the wing root of the aircraft was moved to the nose.

However, Gao Zhendong estimated from the drawings that the original pointed nose might have been improved to obtain a better downward field of vision, but there was no good equipment to install in it, so they simply moved the machine gun at the wing root here and saved the space at the wing root for oil.

If this matter in the letter can be understood at a glance, then the next sentence is not so easy to understand. At least for the current Attack-5 type designers, they can't think of this matter at all, or they have thought of it but don't know how to deal with it.

"Given that the supersonic performance requirement of the aircraft is less than 1.5, the degradation of the total pressure recovery coefficient of the current D-type inlet design under supersonic conditions is still within an acceptable range. However, while the inlet design ensures sufficient intake volume at low speeds, it does not take into account the engine surge problem that may be caused by large intake volume at high speeds. It is recommended to consider adding a high-speed bleed port."

The original Gong-5 with a bare-rod configuration could fly at Mach 1.1, which was barely supersonic, and the adjustable multi-wave inlet seemed unnecessary. Although the Gong-5 at this time had a much greater thrust and a higher speed than the original one due to the benefits brought by 591, tungsten-molybdenum alloy, and computer technology.

But Gao Zhendong has estimated that this speed still does not reach the level that requires a multi-wave system air intake, so Gao Zhendong is not going to complicate things. In view of the fact that our future economic situation is still not optimistic, Gao Zhendong still wants to keep it simple and usable.

However, the engine's air intake conditions are not constant at high and low speeds, so at low speeds, the air intake volume may be insufficient. Later fighter jets generally adopted auxiliary air intakes.

However, at this time, due to the small speed span, this problem is not prominent, and generally a unique method is adopted without an auxiliary air intake.

In this way, the air intake flow at low speed can be guaranteed, but the large air intake volume at high speed may cause the problem of engine surge. Although the aircraft has not been tested at this time and has not been discovered, the hidden danger exists, and may even be exposed earlier than Gao Zhendong saw in his previous life.

Because the Attack-5 in this world was naturally faster than the ones he had seen in his previous life! Because the two engines were better.

When flying fast, problems will naturally arise. Good things bring new problems. Who can I complain to? In the previous life, Master 5 also had to start solving this problem after the modified engine was used and the thrust was increased.

Several designers who were reading the letter looked at each other. This time they did not call themselves stupid. This thing was different from the machine gun layout, which was indeed unexpected. But it was more uncomfortable than doing something stupid, which showed that they had not considered it carefully during the design.

If these two suggested changes were relatively minor and merely minor revisions that did not have a disruptive effect on the aircraft design, then the words in the following letter were a bit alarming to the designers of the Gong-5.

"Given that the aircraft's current combat radius is relatively short, it is recommended that the wing-body fusion method be considered to increase the internal volume of the aircraft, while reducing drag to improve the lift-to-drag ratio. At the same time, it has a favorable effect on the rigidity of the fuselage. If properly designed, it can effectively reduce the weight of the fuselage."

The typical example of wing-body fusion is the American F-16, which is really beautiful.

There were not many early fighter jets that were as thoroughly integrated as the F-16. Although the integration methods and degrees of some other wing-body integrated fighter jets are different, the benefits of wing-body integration are still there, it's just a matter of quantity.

Overall, the larger the size of the connection between the wing and the fuselage, the more benefits you get, but of course there are more disadvantages, such as decreased stability. But this does not mean that only flying wings, tailless delta wings, and truncated delta wings can use wing-body fusion.

Seeing this, the comrades at the Cidu Aircraft Factory were very curious.

Wing-body fusion? What kind of new technology is this? I can understand a little from the literal meaning, but it is still taboo to take the literal meaning when working in technology.

Although they didn't understand, they couldn't help but be tempted by the benefits in the letter. They read on excitedly to see what this "wing-body fusion" was. Then they found out...

Gone!

This thing breaks right here!

Dig a hole and run away!

This would be a few decades later, and it would be the innate holy body of online literature.

But the comrades at the Cidu Aircraft Factory don’t know what online literature is now. They only know that the break is very painful.

Several comrades looked at each other in bewilderment. Finally, Mr. Xiao, who was in charge of the model, comforted everyone, "It's okay. Since the Defense Work Committee forwarded this letter, if we are really interested, it should be no problem to ask the Defense Work Committee."

Everyone then perked up and continued watching.

The following words in the letter may bring even greater changes to the aircraft. "The aircraft is designed with an internal bomb bay, but considering the tactical mission of the aircraft, the existence of the bomb bay is not necessary. Instead, it will cause a sharp drop in the amount of fuel in the aircraft, seriously affecting the combat radius. It is recommended to cancel the internal bomb bay and adopt a full external weapon mounting method."

The basic model of Gong-5 has an internal bomb bay, but when it came to major modifications, this was the first thing to be changed.

The main reason is that the Air Force found that after using it, it basically did not get any of the benefits it had expected, but instead suffered a lot of disadvantages.

The original intention of using an internal bomb bay was to be able to carry two 2-kilogram bombs in extreme circumstances, and to perform low-altitude supersonic penetration in a smooth configuration. In theory, given the battlefield environment in the future, this penetration method has the highest success rate.

But unfortunately, the Gong-5 with this structure has too little oil in the aircraft. Even with two auxiliary fuel tanks, it is only more than 3000 liters.

In addition, the fuel consumption of low-altitude penetration is already high, and the weak-weak combination makes the situation worse, resulting in its "low-low-low" profile combat radius of no more than 200 kilometers, which can be regarded as a typical airport defender.

This pair of auxiliary fuel tanks that must be mounted before launching an attack makes the barely-reachable supersonic speed of the Gong-5 completely meaningless. Before launching the final attack, there is no way of using supersonic speed to travel.

In fact, the comrades at the Cifei Factory were aware of this problem, but in addition to the technical issues, the biggest problem was that the requirement itself was not decided by them.

Gao Zhendong's letter also calculated the benefits of the internal fuel tank.

"According to my preliminary calculations, even without the use of wing-body fusion technology, by replacing the internal bomb bay with an internal fuel tank, the fuel capacity is conservatively estimated to be more than 3500 liters. If wing-body fusion is added, it is expected to reach more than 4000 liters. This amount of fuel can support the aircraft in a configuration of four 4 kg caliber bombs, a 'low-low-low' profile, and high subsonic penetration, with a combat radius of at least 250 kilometers."

In fact, the low-altitude penetration speed of the Type 5 with bombs attached is also high subsonic. In comparison, this "removing bombs and changing oil" actually gains benefits without losing anything.

"If low-drag auxiliary fuel tanks are added, the total fuel capacity is expected to reach more than 5000 liters. With a 'high-low-low-high' profile, the combat radius is expected to reach more than 600 kilometers."

The distance you can cover is longer, so you don’t have to enter at a low altitude at the beginning. It is safer to fly higher in the first half, and it saves fuel.

Gao Zhendong's suggestion was copied from the later improved version of the 5th generation truck. While the size remained basically unchanged, the internal fuel capacity of this model reached about 3700 liters.

Although this amount of fuel seems to be similar to the amount of fuel that can be obtained by using the internal bomb bay and hanging an auxiliary fuel tank, it is different if the external auxiliary fuel tank is hung or not. The external fuel efficiency is far lower than the internal fuel efficiency. Even if a bomb is hung on the fuel tank's rack, the resistance of the bomb is still smaller than that of the auxiliary fuel tank.

Comrades from the Porcelain Aircraft Factory also had some estimates for this data, but seeing the calculation written down in black and white by the comrade who wrote the letter still made me excited. Moreover, this comrade’s reasons were very sufficient and his analysis was very accurate. The Attack-5 with an internal bomb bay was actually unable to penetrate at low altitude at supersonic speed.

But what can we do? What users want is a built-in ammunition bay.

Continuing to read on, the comrade who wrote the letter made a very considerate suggestion: "Considering that the design of the internal bomb bay may be directly related to the initial design requirements, it is recommended that the designer can make a strong presentation of the pros and cons to the user after sufficient theoretical calculation preparation, in the hope of making some improvements."

Hmm? Are we going to contact the Air Force directly and overturn the original technical and tactical requirements? This comrade is quite arrogant and thinks too simply.

But Mr. Xiao has a different idea.

"The Defense Work Committee even forwarded this part of the suggestion as it is. Doesn't that mean..."

A researcher said excitedly: "Mr. Xiao, you mean that the National Defense Committee also has this idea?!"

The Defense Work Committee’s ideas may not be completely consistent with those of the Air Force. If the Defense Work Committee also has this idea, then this matter is not completely set in stone.

Mr. Xiao did not give a direct answer, but turned to look at a key member.

"You should follow the ideas of the comrade who wrote the letter and do some careful calculations and analysis. After all, doing the calculations will help us gain more design experience."

The backbone looked excited: "Okay, Mr. Xiao, I'll finish it as soon as possible!"

After arranging this matter, they looked back at the last suggestion in the letter. After reading this suggestion, the comrades at the Cifei Factory looked at each other and felt that something didn't seem right.

"Boss Xiao, why do I feel like this comrade wants to take our plane back to the original route?"

(End of this chapter)