“NO！ That's impossible! Lin Hongfei, who secretly scolded the damn British, did not have a good thing, was very firm to Elizabeth. Sophie said, "The prototype design of the North County 200 makes it impossible for this aircraft to move the landing gear back, the landing gear cannot be moved back, if you want to lengthen the fuselage, you can only lengthen the rear fuselage behind the wings, the fuselage of the Il-62M is already slender, if it is lengthened by another 6 to 8 meters, I am worried about the strength of the fuselage......

"The problem of strength can be solved ......"

Elizabeth. Before Sophie finished speaking, she was interrupted by Lin Hongfei, "That's right, the problem of fuselage strength can be solved, but how much will it cost?" Is this price a little too much to lose? ”

Faced with Lin Hongfei's sharp question, Elizabeth. Sophie had no choice but to remain silent: extending the second half of the fuselage by 6 to 8 meters is of course theoretically feasible, after moving the engine under the wing, even if the fuselage is lengthened, but because the center of gravity is stable, it can also cancel the Il-62M center of gravity seriously backward, in order to prevent the aircraft from "sitting" on the ground and the unique tail strut, but such a slender fuselage is a big safety hazard.

Rather than considering lengthening the fuselage, it is better to consider directly enlarging the fuselage in equal proportions, expanding the "two floors" of the current one-story cabin and one-floor cargo room, and turning it into a "three-storey" layout similar to Boeing 747, Il-86 and Il-96 with two cabins and one cargo room, although the latter is more difficult.

"Okay, we can talk about the lengthening issue later, but Mr. Lin, what I'm going to say is that in addition to our Rolls-Royce PLC. It is impossible for other companies to provide you with the right engine, whether it is CFM International or IAE, they will not be able to provide you with a 130 kN thrust engine, RB211-535C although the thrust is slightly larger, but this is your only option, isn't it? "Elizabeth. A confident smile appeared on Sophie's face, "It's impossible for IAE to sell you their V2500, and it's impossible for CFM International to sell their CFM56-5B to you, RB211-535C is your only choice." ”

"Who said the RB211 was our only option?" Look at Elizabeth. Although Sophie's expression was very deeply hidden, the sarcasm could still be seen, and Lin Hongfei couldn't help it anymore. slapped his thigh hard, "It's a big deal, I'll use four D-36s!" ”

Four D-36s? After saying this, Lin Hongfei was stunned for a moment: Huh? Seem...... Probably...... Is it really possible to use four D-36s?

Ma Lao and the others once calculated that the Beijun 200, that is, the improved Il-62M, was replacing the steel components with composite materials, titanium alloys, aluminum-lithium alloys and other lightweight and high-strength materials. By replacing bulky and outdated aviation instrumentation and electronic systems with data buses and color CRT displays, the entire aircraft can be reduced by up to 20 tons.

20 tons! That's a staggering number!

This means that the empty weight of the North County 200 after weight reduction is only about 49.4 tons!

Although this weight is still higher than the 41.4 tons of the Boeing 737-800, which has a similar passenger capacity and has just been announced before the opening of the Farnborough Air Show. It is also higher than the Airbus A320's 42.4 tons. But considering the huge gap in the accumulation of skills, Lin Hongfei is already very satisfied with this number.

The Northgun 200 features the enlarged Northgun 100's supercritical wing with winglets, a redesigned flat tail, and a vertical tail and nose fairing, resulting in a more aerodynamic shape with greater aerodynamic efficiency, which is not yet very accurate, but can already be roughly calculated. According to the results of the calculations, the aircraft with a full load would require only 240 kN of total thrust to take off, and the total cruising thrust required for the cruising stage would be between 60 kN and 65 kN.

The prototype of the North County 200: Il-62M has a large fuel tank capacity. Up to 107,000 liters, if you perform the same domestic trunk flight missions as Airbus A320 and Boeing 737, you need to be equipped with a fuel tank with a capacity of 30,000 liters, and the remaining space can be used to load more cargo.

As the initial design is a long-range aircraft flying across the ocean, the North County 200 can also perform transoceanic flight missions, if the use of a large bypass ratio engine with a bypass ratio of more than 4.2, there is no need to retain 107,000 liters of fuel tank, a total of about 75,000 liters of fuel is enough to meet the use requirements, saving 32,000 liters, a total of 32 cubic meters of space, just enough to put a few more standard air containers.

Although the carrying capacity of the North County 200 is far from that of the Boeing 747, which is roughly equivalent to the Boeing 707, it is also the first ultra-long-range heavy aircraft produced by the Republic itself that can fly across oceans, which in itself is a huge breakthrough and of great significance.

CFM56-5B series and V2500 series can meet this requirement, but so far, neither IAE nor CFM International is willing to provide an engine for Lin Hongfei, and Lin Hongfei does not have a suitable large bypass ratio aero engine in his hand. Sophie's angry remark made Lin Hongfei stunned for a moment, which inspired him a new way of thinking.

Using four D-36s? Since the thrust of two D-36s cannot meet the take-off requirements of the aircraft, then I can use four D-36s, so that the total thrust can meet the requirements of the take-off of the aircraft soon?

Since the four D-36s have met the requirements of take-off thrust, Lin Hongfei immediately began to calculate the feasibility in his heart: in terms of the weight of the engine, the D-36 is 1100 kg, the CFM56-5B and V2500 are about 2380 kg, and the weight of the two D-36s is not as heavy as one CFM56-5B, which means that the weight of using four D-36s is even lighter than that of two CFM56-5B or two V2500;

Next question: wind resistance! In terms of the maximum windward cross-section, a D-36 is only about half of the windward cross-sectional area of CFM56-5B, the windward cross-sectional area of two D-36 is almost the same as that of a CFM56-5B, and the windward resistance of four D-36 engines is slightly smaller than that of two CFM56-5B or V2500;

As far as the cruising fuel consumption rate is concerned, the D-36 is 0.663Kg/(DaN.h) although the cruising fuel consumption rate is slightly higher than the CFM56-5B's 0.602Kg/(DaN.h), but the flight of 10,000 kilometers consumes 1 ton of fuel more, which can be offset by the purchase price of the aircraft...... The purchase price of an Airbus A320 or Boeing 737 is not less than 40 million US dollars, according to Ma Lao's calculations, with the current purchasing power, the price of a North County 200 will not exceed 3200 US dollars, how many tons of fuel can be added to the 8 million US dollars saved?

Although the full service life of D-36 is only 30,000 hours, it is still lower than the 36,000 hours of CFM56-5B and V2500, but it is more cost-effective to use D-36.

There has never been a precedent for an aircraft in this class to be equipped with four engines, and although it is a little unusual to equip the North-County 200 with four D-36s, the four engines also bring a huge benefit, that is, if it is a transoceanic mission, the North-County 200 does not need to apply for ETOPS (twin-engine extended range) certification for a minimum of 120 minutes and a maximum of 180 minutes, and does not need to pay attention to any ETOPS.

The so-called double-engine extended range certification is a special requirement put forward by the international civil aviation administration in order to ensure the safe flight of the double-engine aircraft, that is, when planning the route for the aircraft, it must be designed according to such a standard: when one of the engines of the aircraft fails and cannot work, and can only fly by the remaining other engine, it must fly to the nearest alternate/diversion airport within 120 minutes or 180 minutes, but for the aircraft using four engines, there is no such consideration. Even in the worst-case scenario, two of the engines will fail, and two of them will work.

In the history of civil aviation, it has never been heard of an aircraft with four engines having two engines fail in a single mission.

Although ETOPS is mainly aimed at transoceanic routes, in Lin Hongfei's vision, the Beijun 200 itself will be designed with two models, namely a short-range version for domestic flights with a range of 5,000 kilometers and a long-range version that can cross the Pacific Ocean...... The only thing that makes Lin Hongfei feel a little pity is that the initial design of the Il-62M is not very good, it is just a single-deck cabin narrow-body aircraft, if it is a double-decker wide-body airliner similar to the Il-86, it will make a lot of money, but as the most important model in Russia, whether it is the Il-86 or the Il-96, the old and old Maozi refuse to sell.

Nima! Such a simple truth, why didn't we think of it before? Lin Hongfei was pulling his hair in pain...... I forgot, how long did it take for the D-36 engine to reach my hands? I'm still in the learning stage, so I didn't expect it to be normal.

Four D-36s? Elizabeth. Although Sophie is not an expert in aviation, she is half an expert who has been exposed to it all day long, and she knows the performance parameters of the D-36 engine very well. (To be continued......)