However, this time, the central wing box that Lin Guanghua took out was not a traditional small wing box embedded in the fuselage, but a top-mounted central wing box placed on the outside of the fuselage.

The advantage of this is that it can ensure the integrity of the cabin to the greatest extent, increase the volume in the cabin, ensure the loading capacity of cargo, and give more flexibility to the transportation task.

At the same time, the large overhead central wing box is also the largest fuel tank in the whole aircraft, because it is the top of the roof, there is no need to consider the structural bearing of the entire cabin section as before, so it can be made larger than the traditional embedded central wing box.

Although there is a sense of hunchback in the shape of the aircraft, the benefits of this hunchback are also obvious, not only can the wing withstand greater external forces, but also in the wing shape selection is more flexible, and the bearing capacity is also greater, in other words, it can increase the fuel load of the wing fuel tank.

After such a series of optimizations, even if the take-off weight of the advanced light transport aircraft is the same as that of the Y-7 and An-26, the fuel load is 15 to 2 times that of the first two, and with the turboprop engine with a fuel consumption rate of 0308 kg \ kW per hour, it is really not a problem for the advanced light transport aircraft to fly to a range of 5,000 kilometers.

It's just that......

"Old money~~" Zhuang Jianye closed the car door, then rubbed his somewhat swollen head, and said after being a little more comfortable, "I understand your feelings, but some things are not in a hurry, don't say anything else, the overhaul interval during the D-50 test is 1860 hours, do you dare to guarantee that it will be the same as on the test bench when it is sent to the power plant?"

"This ......"

Qian Qiang was speechless by Zhuang Jianye, the data on the test bench is true and credible, but the practical application is another matter, and sometimes the situation encountered is not at all taken care of by the test bench.

Of course, this is not the most important, the key is that the old problem that plagues Tengfei Aviation Power can not be solved, even if many advanced composite materials are applied, there are still various Kaspersky, Qian Qiang and others have not thought of a way to solve it, but after some attempts, without exception, they are ineffective, and finally they can only helplessly maintain the status quo first.

Seeing that Qian Qiang didn't speak, Zhuang Jianye reached out and patted Qian Qiang's emaciated shoulder, "Actually, Lao Lin's side is similar to yours, and the top-mounted central wing box has undeniable benefits, otherwise how can the United States and the Soviet Union use this kind of structure on their strategic transport aircraft? But from another point of view, there are no other countries that can make this kind of structure except the United States and the Soviet Union, why? It's very simple, the first material can't keep up, and the second process can't keep up." ”

Qian Qiang frowned, although helpless, but still admitted that Zhuang Jianye was right, Lin Guanghua's proposal of the top-mounted central wing box structure is good, but this idea is the same as Qian Qiang wants to find a turbine blade material that can withstand the temperature before the turbine at 1600 degrees Celsius, there are many insurmountable gaps.

First of all, the wing box on the top is tantamount to increasing the weight of the whole aircraft, affecting the flight quality and basic performance of the aircraft; secondly, as the most important main load-bearing structure of the aircraft, the strength of the whole component must be very strong.

As soon as these two points are superimposed, there is an irreconcilable contradiction, that is, how to find an excellent balance point to reduce the weight of the structure while ensuring strength.

In this regard, the United States and the Soviet Union have found their own methods and applied them to their own strategic transportation, such as the C5 "Galaxy" and C141 "United Star" in the United States, and the An-124 and Il-76 of the Soviet Union have all applied the top-mounted central wing box structure to varying degrees.

Even Europe is a little worse in this regard, not to mention the domestic one, the gap is even greater.

In such a context, even if Tengfei Aviation Corporation is different, it can't withstand the impact of the general environment, and at most it is just touching the edge of the top-mounted central wing box technology.

Even if there are already a lot of metal matrix composites that can be used, the extremely low production capacity and high price are the biggest obstacles to their large-scale use, in addition to a series of processing processes for new materials need to be solved urgently, the most important of which is the crucial electron beam welding process.

This is the most important welding technology in aero engine and aircraft manufacturing is currently not available in Tengfei Aviation Manufacturing Corporation, which is why the old engine problems of Tengfei Aviation Power can not be solved for a long time, and the overhead central wing box cannot enter the substantive research.

Because without the intervention of this process, all the good plans of Tengfei Aviation Manufacturing Corporation could not be realized.

The most critical reason why the United States and the Soviet Union were able to stand alone in the field of large aircraft was that they had mastered the manufacturing technology of large-scale electron beam welding equipment.

Not to mention anything else, the pinnacle of the Soviet bomber, the wing box of the 160 strategic bomber, is the use of large electron beam welding equipment, the basic welding completed, otherwise the Tu-160 strategic bomber would never have such an elegant body, and domineering combat effectiveness.

"Don't do porcelain work without diamonds, what is our current situation, do you think those three are not clear? They have been going around in various production factories all the year round, studying the equipment of other countries, not to mention what kind of experts it is, but they are also veterans, and their hearts are like mirrors, and they can already be regarded as giving us face if they don't break it. ”

Qian Qiang was still frowning here, Zhuang Jianye added with a wry smile, Qian Qiang immediately raised his head and looked at Zhuang Jianye depressedly, "So, we suffered a loss this time?"

"How is it possible?" Zhuang Jianye looked at Qian Qiang in surprise, "Although the investment in the aircraft has not been pulled, the engine and composite materials can also make pocket money." ”

Hearing this, Qian Qiang sighed rather disappointed, "That's still a loss, the Navy's An-26 is only fifteen, alas~~~ can only be regarded as pocket money." ”

......

The D-46L turboprop engine used for the An-26 modification has roughly the same power and shaft horsepower as the engine equipped with the An-26, but the unit price is 224 yuan, which is 40 more expensive than the turboprop of the same level.

As for the price of the D-50 used in marine gas turbines, it is as high as 3.76 million yuan, which is almost the cost of a small torpedo boat.

The carbon fiber-reinforced aluminum composite materials ordered by the aerospace department are also not much better, and the quotation of 1500000 yuan per kilogram will cost 15 million yuan per ton, which is a sky-high price in domestic materials.

The two departments said that it was not painful, it was fake, but they still gritted their teeth and took out the sticker funds to chop their hands wildly at the Tengfei Aviation Corporation.

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