Although 611 has all the serious financial constraints, Song Lao is not discouraged, he has always been full of energy, hoping that his new fighters will be able to fly one day, and this road is destined to be tortuous.

As a test pilot, Qin Feng, after leaving Song Lao, continued to carry out the test flight of the Jian-7, after all, this is the most powerful fighter in active service.

"Our nose also needs to be counterweighted." On this day, getting off the plane, Qin Feng said to Tu Lao, these days, Tu Lao has been running almost at both ends, constantly urging progress and constantly coordinating.

The planes here do not fly avionics, they mainly fly other projects, but now, they still have a problem.

Counterweights.

An aircraft has its own center of gravity, and the current J-7 is still a statically stable aircraft, that is to say, the center of gravity of the aircraft and the center of lift are in one position.

This has a lot to do with the counterweight of the fighter, if it is not at one point, then the plane will get out of control.

In the past, there was no problem, but now, due to the use of Marconi avionics, although the performance of avionics is higher, the volume and mass are reduced, which causes the nose to become lighter and the center of gravity to move back.

They used Marconi's avionics to counterweight, so that when they fly, it was naturally unbalanced, and they needed to continue to add counterweights in the nose.

This counterweight is an ordinary lead block, more than 100 kilograms of lead.

Tu Lao nodded: "Yes, we still have to add counterweights, we recalculate, add 130 kilograms, it should be appropriate." ”

"It's a waste." Qin Feng couldn't help but sigh.

For the aircraft, the weight of every gram is to be calculated, the hypochondria of the Su-27 of later generations, this is how it came about, the nose radar of the fighter exceeds the design weight, the structure must be strengthened, and after strengthening, it is necessary to reduce the weight, and even the scheme of emptying the girder is used, and the result is congenital hypochondriasis.

People want to minimize the weight, but what about their own side, in order to balance, they actually have to match the plane with a lead block of more than 100 kilograms to counterweight!

With so much weight, if it can be reduced, the performance of the aircraft can be improved somewhat.

"Yes, we can only do this now, but in the later stage, we have finished the construction period, and there are other means." Tu Lao said: "We can change the tail hanging. ”

For the J-7, Tu Lao knows best, he has eaten every part of the J-7 thoroughly, and now, the J-7M aircraft has a certain backward shift in the center of gravity of the aircraft due to the introduction of seven miniaturized foreign electronic equipment and other reasons.

Now in a hurry, everyone is still afraid to carry out new projects, so they can only add counterweight to the nose to maintain balance, but in the future, you can try new ways.

If you don't add weight to the nose, then reduce the weight of the tail, so that you can get the center of gravity back again.

How to lose weight? The best one is the hanging tail.

The current vertical tail is still completely metal structure, the internal frame of aluminum alloy, and the skin of aluminum alloy, although aluminum alloy is very light, it is still not as light as composite materials.

Nowadays, the use of lighter and stronger composite materials has begun to become popular in the world.

In this way, if the counterweight of more than 100 kilograms in the nose is removed, and the tail is lightened by a part, the performance of the entire fighter will definitely be better.

"Tu Lao, do you mean composite materials?" Qin Feng asked, hearing Qin Feng's words, Tu Lao nodded, he liked to communicate with Qin Feng the most, no matter what happened, Qin Feng could think of going with him.

According to the characteristics of composite materials and the development level of domestic composite materials at that time, we can try to use composite materials to manufacture the vertical tail of the J-7 to reduce the weight of the nose and further improve the flight performance.

"In our plan, the composite vertical tail of the J-7M consists of three parts: composite rudder, vertical stabilizer and fairing wall plate. The front and rear girders, skins, wing ribs and reinforcing profiles of the vertical stabilizer were all changed to composite components, while the other structures still retained the original metal parts. Compared with the original metal vertical tail, the newly designed composite vertical tail remains unchanged in terms of aerodynamic shape, bearing capacity and service performance. ”

Tu Lao has long thought about reducing the weight of the tail, and at the same time, compared with the original metal parts, the number of fasteners and parts can be greatly reduced, and the process equipment and assembly workload can be reduced.

Qin Feng nodded: "Composite materials are a trend, however, the process of this thing is still very complicated, and our domestic research on composite components and connection technology is still in the initial stage, and it must be rigorous, and there can be no problems." ”

Composite materials, to put it bluntly, are actually just some kind of plastic, of course, this is a special plastic, Qin Feng knows the benefits of this thing, and the West is studying it, but, compared to metal, it is a nascent stage after all, and it has not been comprehensively studied.

"In addition to moving the tail down, we can also move the wings." Qin Feng's words made Tu Lao stunned for a moment.

The dynamic vertical tail is the same appearance, and the aerodynamics remain the same, but the motor wing is different, the wing is the device for the fighter to generate lift, and it is one of the most important parts of the fighter.

The question of J-7 plus counterweight, in fact, began a long time ago, at the earliest, it was still a negotiation with Jordan, when they wanted an airplane, it was necessary to add missiles on the wings, plus pylons to hang auxiliary fuel tanks, at that time Tu Lao felt that this would destroy the balance, and it was necessary to add counterweights.

At that time, the Jordanians said that they would rather add counterweights than change them, and they knew which was more important.

Now, after changing Marconi's avionics, you have to add a counterweight, and in later generations, many sources say that the counterweight was added to fight the Thunderbolt-8, which is a completely one-sided statement.

If you change the wing, it will be a big project, but if you change the wing, you can directly change the center of lift and balance to the position of the center of gravity, which is the best way to solve the problem.

Tu Lao shook his head: "Qin Feng, this idea of yours is very good, but we can't solve it ourselves." ”

Factory 132 is actually just a fighter manufacturer, and Tu Lao is also a technical talent in the research room of the factory, but he also knows that he is not omnipotent, and Tu Lao can't do it if he changes the wing.

"We can't solve it ourselves, but we can work together with others, we don't have enough technology, so how about adding Western University of Technology? Xigong University is not good, let's add 618 institutes, anyway, we have money in the factory, let's pay for it ourselves and solve the problem by ourselves. ”

The biggest difference with Song Lao's side is that Factory 132 is not short of money.

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