Chapter 106: Proposal Report III

Yang Hui could not afford to concern himself with anything else. It was his turn to report now, and everything had to revolve around the project presentation.

After a brief self-introduction and a clear explanation of his own background and the base’s situation, he began outlining the plan.

He projected two slides at once, and the design concepts for the new aircraft appeared before everyone’s eyes.

When they saw the two proposals, the room was still full of doubt. Although the designs clearly evolved from the J-7, they were obviously very different from it as well.

“As you can see, we have two proposals for the new aircraft. Each has its own emphasis, and each has its own strengths and weaknesses.”

Yang Hui did not need to say any more. After Prince Sultan and Madad had examined the models in their hands and exchanged a look with General Nie, they naturally gained a much deeper understanding of the two schemes.

Madad was the first to speak. “May I ask whether this revised aircraft can truly simulate the flight performance of the J-7? Especially the intake system. I see that both designs have abandoned nose intake.”

The Pakistani side had already studied the question of the two-intake arrangements and concluded that there was no problem.

“Absolutely no problem. We designed it according to the operational requirements of the J-7, while also ensuring strong high-angle-of-attack performance. The side-intake arrangement uses an inward tilt beneath the intake duct, while the chin-intake design inherently has excellent high-angle-of-attack characteristics.”

Hearing that the new modifications would not pose any major issue in imitating the J-7’s flight performance, everyone on the Pakistani side felt reassured. Right now, the priority was still to complete the J-7 pilot training mission. Of course, if they could achieve high-angle-of-attack performance like the F-16, Pakistan would be even more delighted.

They continued discussing the strengths and weaknesses of the two intake designs, hoping to decide as soon as possible which one to adopt.

“First, the side intake. Its disadvantage is that the intake arrangement is somewhat abrupt. When air is drawn in from both sides and guided into the fuselage, the path requires a rather sharp bend, which can easily create small vortices. That is not ideal. Its advantage, however, is that the intake is set higher above the ground, making it less likely to ingest sand and gravel.”

At this point, the people below the podium all felt rather torn. The side-intake option had very obvious pros and cons, and if they wanted to make up their minds, they would have to hear about the chin intake first.

General Nie did not understand the specifics of aviation engineering, but that did not matter. If he did not understand, he could simply ask.

“All right, then tell us about the other scheme as well. Let us hear which one should be chosen.”

The side-intake illustration was removed from the projector, and the chin-intake rendering was placed front and center.

“You can see that the advantage of the chin-intake design is that it frees up valuable space beneath the wings. That area can be fitted with a short-range dogfight missile. In addition, the intake airflow in this scheme is relatively smooth. Its drawback, however, is that it is more likely to ingest sand and gravel.”

Now it was clear. The advantages and disadvantages of the two schemes mirrored each other: what benefited one would become the other’s weakness, and vice versa.

Thinking of the two designs, the choice was indeed a headache. Of course, the ones most troubled were the domestic military representatives; Madad had already made up his mind.

“In that case, as long as it can ensure high-angle-of-attack flight and the vortex issue in the intake can be effectively solved, we choose the side intake.”

Madad spoke decisively, and Prince Sultan naturally followed his lead. Though the model in his hand showed that the intake did look rather abrupt and not especially attractive, that did not matter. As long as it would not suck in sand and gravel, they could tolerate that. Saudi Arabia was in a desert region with plenty of windblown sand; if they used chin intake, who knew how many accidents it would cause.

Setting down the model in his hand, Prince Sultan also said, “I agree with Madad. What we need is takeoff and landing capability under harsh conditions. As for carrying missiles and the like, we do not need to load a trainer with so many practice munitions.”

What else was there to say? Since the foreign side had chosen the side intake, then side intake it would be.

The military had found it difficult to reach a conclusion on its own, but now that the foreign side had decided, it was simpler to follow their lead. Besides, the J-7 had never had this new hardpoint arrangement before.

At last, the military side also agreed to adopt the side-intake scheme. So side intake it was.

A new slide appeared: a top-down view of the side-intake design.

“All right, everyone can see that this new aircraft’s wing profile is different from that of the J-7. It adopts a double-delta wing layout, and we have also added leading-edge maneuvering flaps. This will greatly improve the aircraft’s low- and medium-altitude maneuverability while preserving the J-7’s high-altitude flight performance.”

Hearing that the new aircraft used a double-delta wing, the military representatives immediately became interested. This double-delta layout was indeed a very good choice here. And with this new trainer as a testbed, it could later be directly applied to the J-7. That was excellent; since the opportunity was here, they had to turn the technology into reality.

Being able to improve the aircraft’s low- and medium-altitude performance was also good. If the new aircraft were designed this way, its aerodynamic configuration could indeed come close to the performance of a third-generation fighter. In that case, meeting fifty percent of the third-generation flight training requirements should not be a problem. But to truly achieve that fifty percent of flight performance, one more thing was needed.

With that in mind, Madad raised another question. “In terms of aerodynamics, the new aircraft does indeed meet our design requirements, but aerodynamics alone is clearly not enough. How do you intend to arrange the control system?”

Good aerodynamics alone could never deliver the flight qualities of a third-generation fighter. If they still designed it according to the control-system philosophy of a second-generation fighter, then the new aircraft would be difficult to fly. To widen the gap between the second and third generations, third-generation fighters adopted a relaxed static stability design.

How do you relax static stability? Put simply, you enlarge the wing area. At the same weight, a larger wing area lowers the wing loading. With lower wing loading, maneuverability naturally improves.

Easy to say, but once static stability is relaxed, controlling the aircraft becomes more difficult. At that point, traditional mechanical control systems can no longer meet the demand, so a more advanced fly-by-wire system must be introduced. The only exception was the MiG-29, that oddity.

In the new aircraft’s design, the double-delta wing improved maneuverability, while the aerodynamics also allowed a slight relaxation of static stability.

As for controlling this modestly relaxed stability, the design already had an initial plan, which Yang Hui was about to explain: “For the new aircraft, we have appropriately relaxed static stability. To accommodate that, we have modified the J-7’s original control system and adopted analog fly-by-wire augmentation. The full mechanical control system remains in place, while the longitudinal axis uses a triple-redundant analog fly-by-wire control system, which is more than enough to ensure flight stability.”

What this meant, in essence, was that the new aircraft could not yet be considered a fully fly-by-wire aircraft. Only the most important and least stable longitudinal axis used triple-redundant fly-by-wire. It was better than nothing, really, because the new aircraft had only slightly relaxed static stability.

In fact, the aircraft could even manage without fly-by-wire. Fly-by-wire was added for safety, and also to allow the new design to simulate part of the performance of a third-generation fighter in a fairly reliable way. Most importantly, this provided an opportunity to study a new fly-by-wire flight control system, laying the groundwork for future development.

Fly-by-wire was an imposing term, at least for the Republic’s military at this moment. The military representatives were practically red-eyed with excitement. It was truly no small feat: this mountain-based research institute had managed to secure such a large sum of funding, and now they were even beginning to study fly-by-wire. Impressive indeed.

Pakistan had not expected the control system to be handled this way either. What exactly should this new aircraft be considered? Something between the second and third generation, or something else entirely?

Prince Sultan, as Saudi Arabia’s minister of air force, was very interested in the plan Yang Hui and the others had proposed, and he was quite optimistic about the aircraft’s development. “Your proposal is quite solid. It has advanced aspects and conservative aspects. Although the new aircraft carries some risk, I do not think the risk will be too great. Achieving fifty percent of third-generation flight performance is possible.”

Hearing Prince Sultan speak so highly of the new aircraft, Yang Hui happily expressed the classification he had just come up with for it.

“This new aircraft has already surpassed an ordinary second-generation fighter. It should now be called a second-and-a-half generation fighter.”

There was no such term as second-and-a-half generation at present. That phrase only emerged after the French coined the idea of fourth-generation-plus, and then people began speaking of half-generations. Yang Hui was introducing the term in advance to distinguish this aircraft from a second-generation fighter and, in doing so, raise its prestige.