in2ebook Chapter 1517: Complete Tailless Layout
Chapter 1517: Complete Tailless Layout
Two days later, in the third conference room of Shengfei Group.
Around the oval conference table, there were a dozen engineers of different ages sitting sparsely.
Luo Yang stood in front of the projection screen, and the PPT behind him showed comparative data of all mainstream carrier-based aircraft including the J-15, as well as several fourth-generation fighter jets.
"…Based on the basic research we have completed and the relevant information about the Rafale M obtained from Dassault, it can be basically determined that the canard-delta wing layout will inevitably face the problem of too large an angle of attack and insufficient safety redundancy during the landing phase."
Luo Yang pointed a laser pen at the diagram on the screen:
"On the other hand, the J-20 is 21.2 meters long, which is roughly the same as the J-15 fighter, and cannot alleviate the problem of tight deck space. Therefore, it is basically certain that the J-20 does not have the design basis for conversion into a carrier-based model, and the Navy must choose other options."
He switched to the next slide, which showed a three-view image of the aircraft without the horizontal tail... or, of course, without the vertical tail.
Everyone sitting here is very familiar with——
The "Snowy Owl" proposal with a semi-tailless layout that participated in the bidding for the fourth-generation aircraft that year.
"A few years ago, we invested a lot of effort in the Snowy Owl project. Although it ultimately failed to win the favor of the Air Force, it just happens to have many advantages as a carrier-based aircraft."
Luo Yang explained his thinking in detail.
"Its length is obviously smaller than that of the J-15, and its wingspan is basically the same. Because it uses an internal bomb bay, there is no need to consider the position of the wing folding mechanism, so the parking area can be minimized... In addition, the combined tail wing has a very short projection angle in the horizontal direction, which also saves the trouble of adding an extra set of folding mechanisms..."
"..."
There was a whispered discussion in the conference room, and Luo Yang noticed that several senior designers were quickly recording something.
"More importantly," he continued, raising his voice, "the handling characteristics of the semi-tailless layout are similar to those of the conventional layout, which is conducive to the transition of pilots accustomed to the J-15... After the setback in the bidding that year, the Pre-Research Office has been optimizing this plan in recent years, especially after cooperating with the Aviation Industry Corporation of China, and has made significant progress in the power system."
At this point, Luo Yang turned to Li Chunpeng who was sitting in the corner:
"Director Li, please tell us about the current progress."
Li Chunpeng, director of the pre-research office, a technical expert in his early thirties wearing thick glasses, stood up awkwardly upon hearing this.
If you look at it from a backlit angle, you can even notice beads of sweat on the forehead.
"Uh...thank you Mr. Luo."
He cleared his throat, his voice showing some nervousness:
"For the past four years, we have been working with the team of Academician Chang Haonan of the Aviation Power Group to make targeted improvements to the performance characteristics of the fifth-generation variable cycle engine..."
"Although Academician Chang is still focusing on hypersonic aircraft, many of his aerodynamic research results have been transformed into the Snowy Owl program..."
Having said this, Li Chunpeng suddenly stopped and seemed a little hesitant.
This project has always been under the name of Aviation Power Group, and the progress is only reported to Sheng Fei regularly.
Therefore, when Luo Yang saw the other party's behavior, he subconsciously thought that he had encountered some obstacles in his work.
After all, as the head of a third-level department of a central enterprise, Li Chunpeng is indeed too young and relatively inexperienced.
It’s just that the person he was dealing with was even more outrageous.
So he encouraged her: "It is inevitable that new technologies will encounter difficulties when applied. If you have any questions, please feel free to raise them and we will solve them together."
"It's not a matter of slow progress..." Li Chunpeng pushed up his glasses and explained, "In fact, the progress of the Snowy Owl Project... may not be what everyone imagined..."
Hearing this, Luo Yang and Sun Cong exchanged puzzled looks.
"What do you mean?" Sun Cong asked directly.
Li Chunpeng showed a complicated expression:
"Progress has been so rapid in recent months that the entire plan could undergo... uh... complete changes."
The conference room fell silent instantly.
"In general, the Aviation Power Group has determined that in addition to variable cycle technology, the future fifth-generation engine will also adopt ejection vector propulsion technology that has no mechanical action structure and therefore does not generate additional weight and reliability burden."
Li Chunpeng calmed down and introduced:
"Correspondingly, our Pre-Research Office is also discussing whether to change the design of the Snowy Owl verification aircraft from the initial semi-tailless layout similar to the YF23 to a full tailless layout that eliminates both the horizontal tail and the vertical tail, and provide operating torque through thrust vectoring technology combined with embedded control surfaces... However, we have not yet reached a consensus, so we have not reported it to the group."
"what?"
The conference room suddenly exploded.
Soon someone asked: "Does this mean... a flying wing layout?"
Luo Yang raised his hand to signal for everyone to be quiet: "Let Director Li finish what he is saying."
Li Chunpeng turned on the computer and opened a rendered 3D design drawing.
Soon, an unprecedented aircraft design appeared on the projection screen - a smooth wing-body fusion without any protruding control surfaces, like a sharp blade.
The conference room was completely silent. Everyone was shocked by this huge change.
Luo Yang was the first to come to his senses:
"But the biggest obstacle to achieving a tailless solution is probably not the control torque but the heading stability...Without a vertical tail, it is easy to go into a tailspin at a high angle of attack. How do you plan to solve this problem?"
"There is no engineering solution yet, but the theoretical basis has been determined." Li Chunpeng switched to another PDF file, showing a set of complex fluid mechanics equations and pressure distribution diagrams. "By constructing a series of compression and expansion flows in the high-speed flow field, a high-pressure area can be generated on the windward side of the rear body of the aircraft, and a low-pressure area on the leeward side..."
He pointed to the changing flow chart on the screen:
"Combined with the rear body surface with a lateral projection area, a heading stabilizing moment equivalent to the vertical tail can be formed... Simply put, we do not use a physical rudder surface, but an 'air rudder' to maintain stability."
Quiet.
Even the air seemed to freeze.
A few minutes later, an aerodynamics expert suddenly knocked on the table: "It completely subverts the traditional design concept... But we must admit that Director Li's plan is quite genius and feasible."
Luo Yang walked to the screen and studied the complicated charts carefully.
As a senior aerospace engineer, he immediately realized the revolutionary significance of this plan.
No movable control surfaces means lighter weight, lower radar cross-section, and simpler mechanical structure.
"So, what about at high angles of attack?" Luo Yang asked. "It is logical in level flight, but as the angle of attack increases, the protruding rear body's ability to interfere with the flow field decreases, and the pressure asymmetry between the windward and leeward sides decreases. The heading stabilizing torque provided by the rear body will certainly decrease."
Facing the technical problems, Li Chunpeng was actually more relaxed than before:
"We found that when the distance between the two tail nozzles is increased, the change in the curvature of the rear body surface causes the concave area of the rear body to produce an opposite heading instability moment, which reduces the total heading stabilization moment generated by the wide-spacing rear body."
"As the angle of attack increases, the low pressure area in the concave region generally moves toward the windward side, and the inner and outer surfaces of both sides of the wide-spaced rear body form a heading stabilizing moment. Although the heading stabilizing moment formed by the pressure difference on the outer surface of the rear body is slightly reduced at this time, the total heading stabilizing moment does not change much."
Luo Yang turned around and looked at the pressure distribution cloud map on the projection screen.
Apart from facing Chang Haonan before, he finally had the feeling of "the waves behind push the waves in front" again.
Fifty years old is still the prime of life for an aerospace engineer, but he can no longer keep up with the thinking of these young engineers.
"Have you reported to Academician Chang?" He turned to Li Chunpeng, his voice trembling slightly with excitement. "Also, what specific difficulties do you have at present?"
"Not yet. This is entirely our internal thinking." Li Chunpeng answered honestly, "The biggest challenge at present is the flight control system - we need a new set of control laws to coordinate vector thrust and embedded control surfaces... But with the current team size... I'm afraid it's difficult to advance both the traditional layout and the tailless layout at the same time..."
After pondering for a while, Luo Yang finally made a decision:
"First, follow your ideas and concentrate resources on the complete tailless solution... If you are really unsure, the group can allocate some resources to support you in developing a small or medium-sized drone to practice..."