Chapter 1212: Ammunition Bay Improvement

"The Tu-160 can indeed launch Kh15 supersonic anti-ship missiles at supersonic speeds, but that's not the problem..."

Faced with this question, Jiang Jianjun scratched his head in distress:

"If a rotating launcher is installed, the dropped ammunition is actually located at a fairly shallow position, and because the launcher structure occupies most of the space, the interior of the ammunition bay is not a traditional rectangular or quasi-rectangular structure... These two factors work together to make the static pressure flow situation relatively simple, and the weapon delivery process is similar to the conventional external mode..."

"But after removing the rotary launcher, the bomb bay of the Tu-160 will return to the traditional internally embedded rectangular structure... Our previous bomb bays, the H-5 and H-6, were subsonic aircraft and would only carry free-fall bombs in the bomb bays, so there would not be much impact. However, under supersonic conditions, the bomb bay structure would affect the flow pressure distribution on the bottom surface, producing aerodynamic effects on the dropped ammunition."

This section is relatively complicated.

"Will even heavy ammunition be affected?"

As they were talking, they had already left the helipad and arrived at a factory not far away.

All along, the No. 41175 machine has been undergoing various tests and modifications here.

"As far as the flow field caused by a 300-ton aircraft is concerned, there will probably be no difference between a 6-ton ammunition and a 600-kilogram ammunition."

While explaining, Jiang Jianjun motioned the two technicians who had just obtained the data to come forward.

The two men held several metal boxes of different colors in their hands, which actually corresponded to storage devices with different categories of parameters.

Jiang Jianjun took out the orange one and connected it to a computer next to him.

Soon, a dense array of numbers appeared on the screen, which even made people dizzy at first glance.

But after a few clicks of the mouse, the abstract tabular data becomes intuitive and visual image content.

Only then did Jiang Jianjun continue to speak:

"The entire bomb bay of the Tu-160 is nearly two meters deep, which is equivalent to a length-to-width ratio of less than 6. The entire structure will become a deep cavity, thus forming a supersonic open-bay flow."

"In this case, the free flow separates from the leading edge of the bomb bay, and the shear layer separates the far-field free flow from the internal flow. The pressure distribution on the bottom of the bomb bay is roughly uniform, and is only slightly higher at the trailing edge. It is relatively safe for the carrier aircraft itself, but the shear layer across the entire space structure will hit the rear wall of the bomb bay, causing high-intensity aerodynamic noise, causing the carrier to vibrate during the throwing process..."

Qiao Chenqing is not an expert in aerodynamics, but he can still understand the concise schematic diagram.

Missiles generally use a thin shell structure, which cannot withstand much tossing compared to the thick-skinned iron bombs. Excessive vibration is likely to cause damage to the precision components inside.

Moreover, the verification bomb uses hydrogen-oxygen cryogenic propellant, so extra caution is required.

After thinking for a moment, he continued to ask:

"I've seen the rough parameters given by Academician Chang... The diameter of the verification missile is slightly less than one meter. Can we set up a partition in the middle of the missile bay and only use the lower half of the space?"

"The chief minister's idea is right, and this is the solution we are currently considering."

Jiang Jianjun flattered his leader a little.

But his tone changed immediately:

"However...the closed bomb bay flow formed by the shallow cavity structure also has hidden dangers."

He then pulled up another flow diagram:

"In this case, the incoming flow separates from the leading edge of the bomb bay, but does not have enough energy to cross the bomb bay, causing the flow to hit the bottom of the bomb bay and separate again before reaching the rear wall of the bomb bay. The separated flow reattaches to the rear wall of the bomb bay, forming a low-pressure area near the front wall and a high-pressure area near the rear wall."

"These two obvious flow separation areas, one moving downstream of the front wall and the other moving upstream of the rear wall, generate a pair of opposite static pressure gradients. The reaction on the mount is to generate a very large lifting moment..."

"We have not yet verified the detailed aerodynamic shape of the missile, so it is difficult to assess the specific impact of this torque. However, even if we estimate it in the best case scenario, it will obviously destroy the ignition posture of the missile, causing a large amount of fuel to be consumed for adjustment after launch, affecting the range and the ultimate maximum speed achieved..."

Qiao Chenqing stared at the picture on the computer screen for a long time before slowly letting out a breath:

"What about the worst-case scenario?"

Jiang Jianjun wiped the sweat from his forehead:

"If the center of gravity of the bomb carrier is relatively far back and the flow intensity is relatively strong, it is possible to cause a complete loss of balance, or even cause the projectiles that have left the bomb bay to be pushed back by the airflow and hit the aircraft itself..."

"..."

For a moment, everyone around fell silent.

"I remember that the US military seemed to have lost a lot of planes for this reason?"

Seeing that the atmosphere was a bit too heavy, Qiao Chenqing slightly changed the subject.

"Yes."

Jiang Jianjun replied:

"In some specific cases, even if the aircraft does not have a bomb bay in the physical sense, a closed flow similar to a shallow cavity structure will still form under the wing or under the fuselage, causing the weapon to rise after being released, resulting in damage to the aircraft itself."

"However, the scale of the closed flow formed by external mounts is generally small. We only need to give the projectile an initial velocity through the ejection rack so that it can leave the dangerous position when released. The downwash zone formed by the real bomb bay, especially the large-sized bomb bay of the Tu-160, is very large and cannot be completely avoided by a single ejection rack..."

What Qiao Chenqing was thinking about at this moment was actually another more long-term issue.

"If that's the case, then the weapons bays of tactical aircraft... like the F22, will they also face the same problem?"

After all, using Tu-160 to launch air-launched cruise missiles is a one-time deal, and there is a high probability that it will not happen again.

But the fourth-generation fighter jets of the future will have to be equipped in batches.

Jiang Jianjun nodded:

"So, on this subject, we are cooperating with several brother units such as the 601 Institute and the 611 Institute..."

He had only said half of his words when he noticed Qiao Chenqing's face becoming increasingly gloomy.

So I quickly changed the subject:

"However, the size of a tactical aircraft is small after all, so the flow field impact after the bomb bay is opened is relatively weak, not as serious as the situation we are facing... In addition, the reason why we chose to use a shallow cavity bomb bay is because we already have some ideas to solve the problem, such as controlling the opening of the bomb bay door and providing an initial negative angle of attack for the bomb load..."

"..."

Just as the atmosphere gradually became stalemate, a staff member hurried in from the door and approached Jiang Jianjun and Qiao Chenqing:

"Commander, President Jiang, we just received the documents sent by Academician Chang and the First Academy of Aerospace."

Jiang Jianjun raised his eyes slightly:

"Is it to verify the specific design parameters of the missile?"

The staff member nodded, but did not leave.

Instead, he placed a folder in his hand on the table:

"In addition... Mr. Chang also attached a letter, saying it was addressed to the person in charge of design at Gaofa Group."

Jiang Jianjun was stunned after hearing this, and hesitantly opened the document in front of him.

Apart from the letterhead, there was only one sentence written on the entire A4 paper:

"The large bomb bay of the Tu-160 aircraft may cause turbulence in the flow field. For this problem, it is possible to consider setting a spoiler at the leading edge of the bomb bay and setting a specific inclination angle at the trailing edge to alleviate it."