Chapter 380 High Angle of Attack and High Maneuverability (HARV) Technology Demonstration Machine
In addition to the changes in the shape of the outer edges of the wings and vertical tail that were seen in Ding Gaoheng’s office, as well as a set of extra fuel tanks on the back of the aircraft , the design plan before Chang Haonan also modified the shape of the wing, extending directly from the root of the leading edge of the wing to the side of the canopy.
Because the length is too exaggerated, it may even cause the pilot’s crotch to get stuck when getting on and off the plane. Therefore, in your plan, a small folding boarding ladder is inserted under the side strips...
“It’s quite well thought out...”
It doesn’t actually matter whether a land-based aircraft has its own boarding ladder, but if it is to be put on a ship in the future, it still needs to be Quite necessary.
After all, the land on the aircraft carrier deck is precious and the number of ground crews is limited. It would be the same if there were fewer bits and pieces around the aircraft.
Of course, the Chinese aircraft designers in 1997 would definitely not follow the carrier-based aircraft. The design is based on the standard, which is probably just to make use of the invalid space under the side wings.
Chang Haonan didn't even need to calculate such an improvement, he knew that it must be specifically to enhance the aircraft's control performance within a specific angle of attack range.
After such modifications, the entire aircraft looked a bit like an F18 with a single vertical tail and a single engine.
“After returning from Chengdu last time, we made a complete overhaul of the JJ-7 according to your ideas. At present, the aerodynamic design of the first version has been basically completed.”
Seeing that Chang Haonan had opened the project file, Sun Huizhong hurriedly came to the side and introduced the results of his recent work while taking out a stack of photos from his pocket:
“One of the current problems is that it is really not I knew how to design the DSI air inlet, so I first used an ordinary D-shaped baffle air inlet instead. The other reason was that due to the conditional factors, there was no way to do structural calculations, so I just made a wooden model for the time being. Let’s fill in the internal equipment and take a look.”
Chang Haonan took the photo and looked at it briefly.
It’s really a bit fresh.
In his last life, when he entered the aviation industry and finally came into contact with aircraft design after many hardships, even the Beijing Olympics was about to start, so naturally he had never been exposed to this traditional craft.
"I'm not telling you that, Mr. Sun, your model is quite good. It feels like it could be a handicraft."
"Alas... I'm ashamed to say that in these years, our Guizhou Airlines has developed the best business. , that is, wooden furniture, even exported to several Middle Eastern countries.”
As an aircraft designer, Sun Huizhong is always a little embarrassed when it comes to mentioning this matter -
The aircraft manufacturing company, even Aircraft have not been exported, but furniture has been exported.
But this is nothing to Chang Haonan, who came back from more than 20 years ago.
As for side jobs, of course you can do some if you have the conditions.
Chang Haonan did not dwell on the internal structure for too long.
As far as a simple light trainer aircraft is concerned, it does not require particularly exaggerated structural strength. The focus of optimization is mainly to reduce weight as much as possible. It can be handed over to Guizhou Airlines for practice.
"I see that you have made some changes in the design of the wing. Is it to improve the linearity of the lift curve at small and medium angles of attack?"
Hearing this question, Lin Tongxin, who had been staying behind Sun Huizhong just now, suddenly lit up:
"Director Chang, have you... seen it?"
In fact, in terms of age, Lin Tongxin, who graduated with a Ph.D., is several years older than Chang Haonan, but after this period of experience, the latter has already shown signs of There are not many traces of being a bachelor's degree graduate in his early twenties, and coupled with his current position, if they don't know more about him, most people will think that although he looks young, he must be in his late thirties.
“This design was proposed by Xiao Lin after he joined the company. After modifying it, we simply calculated it ourselves and found that it is indeed good for improving maneuverability.”
Sun Huizhong explained next to him.
“Of course, small-sized slat wings, or structures similar to slat wings, are the main reason why the slope of the lift curve of the aircraft decreases at small and medium angles of attack. For early mechanical or analog fly-by-wire flight controls, , this strong and irregular nonlinearity is very difficult to control.”
Chang Haonan put the photo aside, picked up the mouse again, and enlarged the upper part of the screen:
"The early designs of Su-27 and F15 both suffered losses in this regard, and I miss you. I should have found some inspiration from F18.”
“This... is all right.”
Lin Tongxin instantly became excited:
"This is the conclusion that my supervisor told us when I was working on a project for my master's degree. I didn't pay much attention to it at first, but I encountered a similar situation as soon as I joined the job this year..."
The other party's reaction made Chang Haonan couldn't help but smile. He recalled that when he had just graduated and entered the aviation industry in his previous life, he seemed to be in a similar state to him...
Then he was quickly taught a lesson by reality.
There is still some difference between actual work and what you learn in school. In fact, many early third-generation aircraft with slatted wing designs face the problem just mentioned, that is, the aircraft can maintain a certain degree of maneuverability at large angles of attack, but is prone to losing control at medium angles of attack.
That is, the torque characteristics are very poor.
Many seemingly strange designs were born to solve this problem.
It’s just that the development of aerodynamics far exceeded initial expectations. By the mid-to-late 1990s, there were already many ingenious designs to improve the linearity of torque, combined with the advancement of flight control technology. Huge progress, this problem has virtually ceased to exist.
Thinking of this, he decided to say a few more words:
"The knowledge learned is indeed very solid, but I still need to work hard on learning and applying it."
Just now, Lin Tongxin, who thought that his idea was completely guessed and recognized, suddenly turned pale:
"Ah this..."
"It must have been the early 1990s when I was studying for my master's degree. The situation was still somewhat different from now. In fact, with the response speed and control capabilities of today's fly-by-wire flight control, as long as the design If the level is appropriate, there will be no problems in this regard."
At this point, Chang Haonan pointed to the vertical tail of the aircraft on the computer screen and said:
"On the contrary, you designed it like this. The side strips may induce a divergent oscillation in the tail part, which is a test for the strength of the vertical tail root. If you observe carefully, you will find that three sets of stiffeners are designed at the vertical tail root of the F18 to deal with this problem. "
"This..."
Lin Tongxin had felt relatively good about himself just now, but when he was told this, he suddenly felt a little embarrassed and had to scratch his head in embarrassment.
Of course, Chang Haonan also knows that at this time, he cannot blindly undermine other people's self-confidence, so he changed the topic:
"But, can you have ideas in this regard, not just Mechanically executing the leader's instructions is already better than many people."
The reason why I say this is definitely not that Chang Haonan was in Versailles.
After all, there are very few geniuses who can change the world on their own.
Take him for example. Without the help of the system, he could certainly achieve some impressive results by relying on his experience and skills in his previous life, but it would never be possible for him to reach this point.
The career development route of most people is gradual.
The key is to have the opportunity, resources and courage to try.
So although this Lin Tongxin may not be very strong spiritually, he is definitely a malleable talent.
If nothing else, how many people, after graduating with a Ph.D., can still recall a casual remark made by their supervisor while working on a project at the master's level?
But he remembered it.
"If you are interested, I happen to have a simpler solution here, which can further improve the available angle of attack based on the original design."
Chang Haonan said from the side I pulled out a piece of graph paper and drew a picture on it:
"Designing a small retractable side strip on the side of the nose can weaken the asymmetric vortex generated by the asymmetric vortex of the nose at a high angle of attack. The steady-state lateral force and yaw moment can also utilize the lateral force generated by the edge vortex to generate a moment that hinders yaw. In addition, the size of the nose edge is almost negligible compared with the wing and tail. It doesn’t matter, so it won’t affect the longitudinal aerodynamic balance you have already done.”
“However, the telescopic structure takes up a considerable part of the nose space, so it is really useless for a fighter jet that pursues the size of the radar antenna. This design has not been applied to a specific model. ”
He handed the schematic diagram he drew to Lin Tongxin next to him:
"If you are willing, you can take advantage of this period of time in Beijing to try it on this new training aircraft to see if you can build a specialized The large-angle-of-attack high-mobility technology verification aircraft is released. ”
“On the one hand, the training aircraft has certain requirements for the controllability of ultra-large angle-of-attack. This solution is very low-cost compared to other methods and can be used. Is it useful? On the other hand, it can also be regarded as an opportunity for your airline to show its face. Selling aircraft is sometimes the same as selling other things. You have to come up with some gimmicks to get people to pay attention... "
Now that we have talked about this, how could the latter have any reason to refuse? He immediately took the graph paper with both hands:
"Of course I am willing. Thank you Director Chang for the idea. And opportunity! ”
Writer's Assistant has a new green content plan. When I posted the last chapter, I clicked on it and tried it, but it directly deleted the next paragraph of my content... As a result, the last chapter was almost less than 2,000 words...< br>
(End of this chapter)