Application background: Early aircraft wings were all straight. Originally a rectangular wing, it was easy to make. However, due to its wide wing tip, it will bring drag to the aircraft and seriously affect the flight speed of the aircraft. Swept wings: Breaking the "sound barrier" in one fell swoop. German, British, and American jet aircraft took to the skies one after another. Aircraft began to enter the jet age, and their flight speeds increased rapidly, soon approaching the speed of sound. A "shock wave" appears on the wing, causing the air pressure on the wing surface to change. At the same time, the aircraft's resistance suddenly increased dramatically, becoming more than ten times or even dozens of times greater than when flying at low speed. This is the so-called "sound barrier". In order to break through the "sound barrier", many countries are developing new types of wings. The Germans discovered that making the wings swept back, like the wings of a swallow, could delay the generation of "shock waves" and alleviate the instability of the aircraft when it approached the speed of sound. However, a swept-back wing produces less lift under the same conditions than a straight wing that is not swept back. This has an adverse effect on the take-off, landing and cruising of the aircraft, and wastes a lot of time. Necessary fuel. Is it possible to design a wing that can adapt to various flight speeds of the aircraft and have the characteristics of both speed and speed? This became the biggest issue facing the aviation industry at that time.
What are the economic and social benefits: The new design abandons the traditional fixed-wing design concept so that the wings can match the corresponding flight attitude at different speeds and have straight wing lift. When flying at high speed, its wings are swept back as much as possible, with a sweep angle of up to 72.5 degrees, becoming like a delta wing, so it can easily break through the "sound barrier". , thereby effectively reducing the windward area (that is, the cross-sectional area of ??the airflow acting on the surface of the aircraft), achieving the purpose of saving energy and reducing consumption, and increasing the flight speed, and ultimately achieving the fundamental purpose of improving its combat effectiveness.
Problem description: According to the above analysis, the technical contradictions in the system are:
Traditional fixed wings are not suitable for high-speed flight. They generate very large resistance when breaking through the sound barrier and consume a lot of energy. The energy increases accordingly, and it is easy for the aircraft to disintegrate in the air;
The delta wing is not suitable for low-speed flight, and the lift generated under the same thrust conditions during takeoff, landing and cruising is small, and the corresponding energy consumption is correspondingly Enlarged.
In short, the contradiction is concentrated in the contradiction between speed and energy consumption in motion.
Solution ideas and key steps:
Using the technical contradiction matrix in the TRIZ theory, the technical characteristics involved:
19# Energy consumption of moving objects
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9# Speed
Looking at the technical conflict resolution matrix, you can get the following four innovative principles:
8# Weight compensation
15# Dynamic characteristics
35# Changes in physical or chemical parameters
38# Accelerated oxidation
Adding counterweights is obviously not suitable for this kind of fighter. Fighters require a light body and flexible maneuverability. Moreover, the heavier body also worsens the technical characteristic of speed.
Although powerful oxidizer can make the fuel burn more fully and obtain greater thrust. However, fighter jets use special high-calorie aviation kerosene, which is relatively fully burned in the turbojet engine, so the effect of using this innovative principle is not very obvious.
For:
15# Dynamic characteristics
35# Changes in physical or chemical parameters
Considering these two innovative principles.. By modifying the wing, it becomes a movable part, and the shape of the wing is effectively controlled during flight, so that it can change the "sweep angle" within a relatively large range, and obtain a straight wing to a delta wing. The advantage is to obtain different flight conditions from low speed to high speed, showing strong adaptability.
When the F111 fighter jet is flying at low speed (Figure 1), it is in the take-off stage. The wings are straight, obtaining greater lift, good low-speed characteristics, and avoiding wasted energy in long-distance taxiing. , thus effectively solving the contradiction between the speed and energy of the aircraft at low speed.