The overall scheme design of the aircraft, especially the military aircraft, involves the tactical and technical requirements, the determination of the main parameters of the whole aircraft, the preliminary shape and size estimation and verification of the fuselage, the drawing of the three-sided diagram of the aircraft, and the arrangement of the parts of the whole aircraft.

These are very complex jobs. First of all, it is necessary to analyze and calculate the intrinsic relationship between the tactical and technical requirements of the aircraft and the total mass of the aircraft. The weight of the whole aircraft when taking off is called the take-off weight, in the overall scheme design stage, the take-off weight of the aircraft needs to be divided into several parts, one is the structural weight, the second is the propulsion system weight, the third is the equipment weight, the fourth is the fuel weight, and the fifth is the payload weight.

The requirements in this tender are that the maximum take-off weight of the bomber should be more than 20 tons, the range should be more than 4,000 kilometers, and the maximum bomb load should be more than 4 tons. According to these requirements, coupled with the characteristics of the flying wing layout, the power and weight of the Wind Thunder turboprop engine, the Holden brothers estimated the maximum take-off total weight of the flying wing bomber to be about 25,000 kg; The maximum bomb load is estimated at 5,000 kg, due to the airframe space advantage of the flying wing layout, which can accommodate more bombs; 2. Wind and thunder turboprop engines with a total weight of 1600 kg; In terms of structural weight, since the structural weight brought by the flying wing can be reduced by 10%, the structural weight of the whole aircraft is estimated to be 6,000 kg, and the weight of the equipment is estimated to be 3,000 kg, so that the total weight of the fuselage is 10,600 kg.

For a long-range bomber, in order to ensure its large range, the load of fuel must be enough, generally reaching about 50% of the total weight, although the flying wing layout aircraft has a high lift-to-drag ratio and much lower fuel consumption, but it is also a good thing to have a larger range. As a result, the estimated fuel weight is also 10,000 kilograms. Together with the payload mass, that is, the normal bomb load of 4000 kg, as well as the rest weight of the crew, the maximum total take-off weight of the flying-wing bomber is 25000 kg.

This, of course, is the distribution at the time of take-off with a normal bomb load. At the time of take-off with the maximum bomb load, the fuel weight was reduced to 9,000 kg. This will reduce the range accordingly. This relates to the relationship between aircraft fuel consumption and range. The fuel consumption of the 2 wind thunder turboprop engine in the cruising working state is 0.35 kg/horsepower. hours, the power of each thunder turboprop engine in the cruise is 1500 horsepower, the fuel consumption per hour is about 500 kg, the total fuel consumption per hour is 1000 kg, the available fuel volume is 0.9, and then the take-off fuel consumption is removed, and the available fuel capacity in the middle is about 9000 kg when carrying bombs normally, so the endurance of this flying wing bomber is about 9 hours. Based on the cruising speed of 500 kilometers per hour, the combat range reaches 4,500 kilometers, which fully meets the requirements of the German Ministry of Defense. In addition, when flying with a maximum bomb load, the endurance time is reduced to 7 hours, and the range is 3,500 kilometers.

Xiao Weiguo looked at the Holden flying wing scheme in his hand and said loudly: "Let's look at the performance parameters of our flying wing scheme!" The results of such estimates also exceed the requirements of the indicators by a cut of margins. If some optimization is made, I believe that the performance of the flying wing bomber can be improved. ”

Messerschmitt exclaimed: "Yes. In this way, our flying wing layout scheme also exceeds the requirements of the German Ministry of Defense in terms of bomb load, and the same is true in terms of range. Due to the use of two high-power wind and thunder turboprop engines, the thrust-to-weight ratio of the whole machine is high. Therefore, the cruising speed and maximum speed estimation results are also very ideal, so this scheme is very advantageous! ”

Xiao Weiguo nodded and said, "Yes, I'm also very optimistic about this flying wing scheme." Of course, it still leaves a lot to be desired. Further research is needed. First of all, a reduced version can be manufactured for test flight verification, after all, the aerodynamic layout of the flying wing, which is also the first in the world, is very risky, first with a small proportion of the flying wing aircraft for test flight, you can find out the control characteristics of this aerodynamic layout. ”

The Horton brothers also made estimates of flight weight and landing weight. Normal flight weight is the weight of the aircraft with a certain amount of residual fuel, which is used in the calculation of flight performance, for example, to calculate the thrust-to-weight ratio. The normal landing weight of the aircraft is 20% of the fuel and 50% of the ammunition, and the normal landing weight of this flying wing bomber is almost 12,000 kg, and the maximum landing weight needs to be calculated for structural strength, which is estimated at 20,000 kg. Under normal circumstances, the bomber needs to be used before returning to landing, and if it is greater than this weight, it must release fuel or throw away the bomb to ensure that the weight of the whole aircraft is less than this maximum landing weight.

Then the aircraft parameters are also calculated, since the aircraft layout has been determined as the flying wing layout, the thrust-to-weight ratio and wing Daiho, as well as the aspect ratio, relative thickness and sweep angle in the wing parameters. Then arrange and draw the main structural parts of the aircraft, such as the position and installation of the engine, the layout of the fuel tank, the arrangement of the landing gear, etc.

According to Xiao Weiguo's suggestion, the Holden brothers designed this flying wing bomber with a wing sweep angle of 34 degrees, a aspect ratio of about 7, a length of 12 meters, a wingspan of about 30 meters, a wing area of 160 square meters, and a maximum wing load of 160 kilograms per square meter.

Messerschmidt exclaimed: "This is really an amazing bomber, I want to wait until this flying wing bomber comes out of our factory and flies into the blue sky, I am afraid that it will cause a sensation all over the world." ”

Xiao Weiguo said: "That's right, this kind of design that breaks through the tradition will indeed make people shine, not only the performance is much higher than the usual layout, but also as a bomber, it also has a special advantage, that is, stealth in front of the radar." But it's really complex and requires careful design and tuning. Now the Horton brothers have only roughly estimated the parameters of this flying-wing bomber scheme. Next, we will carry out systematic research and detailed design, and strive to complete the plan as soon as possible, and we still have a lot of work to do. ”

Messerschmitt was surprised: "Can it still be invisible?" Is this true? ”

Xiao Weiguo said with a smile: "The flying wing bomber is completely smooth from the direction of the abdomen, and when the landing gear is put into the fuselage, there is no superfluous protrusion at all. Looking at its overall structure, the nose is triangular, the tail is presented as a W-shape, and the engine intake is in the back of the aircraft, so when the radar wave emitted from the ground radar is mostly refracted in all directions, it will not be reflected back to the direction of the radar wave transmission. In this way, the stealth of the radar is realized, that is, the radar can hardly detect the bomber flying in the sky. (To be continued.) )