RU2820266C1 - Aircraft fuselage - Google Patents

Abstract

FIELD: aviation.

SUBSTANCE: invention relates to aircraft engineering, particularly, to subsonic and supersonic passenger and transport aircraft fuselages. Aircraft fuselage comprises nose part, mid part conjugated with aircraft wing root part and aft part bent upwards relative to fuselage horizontal line and convex outer contours of cross-sections. At the same time the lower parts of outer contours of the aft cross-sections are made with a kink at the point of their intersection with the vertical plane of symmetry of the fuselage.

EFFECT: reduced inductive resistance of aircraft in cruising flight modes.

2 cl, 6 dwg

Description

The invention relates to the field of aviation technology, to fuselages, mainly of passenger and transport aircraft with subsonic and supersonic flight speeds.

The fuselage is one of the main elements of the aircraft and is designed to accommodate transported cargo, passengers and various equipment. The fuselage of the aircraft can also house power plants and fuel for their operation. The fuselage does not make a significant contribution to the creation of lift, but creates significant drag, up to 50% of the total aerodynamic drag of the aircraft, see, for example, [Küchemann D. Aerodynamic design of aircraft. M.: Mashinostroenie, 1983].

To reduce the drag of the fuselage, it is given a well-streamlined shape, which includes a nose part 1, a middle part 2 mating with the wing center section 3, and a rear part 4 with convex external contours of cross sections 5, see Fig. 1. On most passenger and transport aircraft, the aft part of the fuselage is curved upward relative to the horizontal line in order to prevent the aft part of the fuselage from touching the runway during takeoff and landing modes. The upward curvature of the aft section is also used to improve the efficiency of the tail mounted on the aft fuselage by placing it higher, see for example [Jame's. All the World's Aircraft. Passenger aircraft of the Tu, Il, An, Boeing, Airbus brands].

The fuselage of the TVRS-44 passenger aircraft, developed by the Ural Civil Aviation Plant (UZGA) was chosen as the prototype [Vzlet magazine, 2021, No. 3-4, pp. 12-15].

The disadvantage of the prototype is that the upward bend of the aft fuselage leads to upward deflection of the current lines 6 flowing around the upwardly curved aft fuselage. The upward deflection direction of the current lines 6 created by the upwardly curved aft part is opposite to the downward deflection direction of the current lines 7 created by the aircraft wing, see FIG. 1. The interaction of upwardly deflected streamlines 6 flowing around the curved aft part of the fuselage with downwardly deflected streamlines 7 flowing around the aircraft wing leads to unevenness 8 in the distribution of flow bevels 9 behind the aircraft along the wing span, see Fig. 2. The created unevenness (inconsistency) of the flow bevels along the wing span behind the aircraft leads to an increase in induced drag and a decrease in the aerodynamic quality of the aircraft at cruising flight modes [Kücheman D. Aerodynamic design of aircraft. M.: Mechanical Engineering, 1983, p. 76].

The objective and technical result of the claimed invention is to reduce the inductive drag of an aircraft during cruising flight conditions.

The solution to the problem and the technical result are achieved by the fact that in the fuselage of the aircraft, including the nose part, the middle part mating with the root part of the aircraft wing, and the aft part, made with an upward bend relative to the construction horizontal of the fuselage, and convex external contours of the cross sections, the lower parts the external contours of the cross sections of the aft part are made with a break at the point of their intersection with the vertical plane of symmetry of the fuselage. The bend angles of the lower parts of the external contours of the cross sections of the aft fuselage on the inner side of the contour are made in the range from 180° to 30°.

The essence of the claimed invention lies in the fact that the proposed implementation of the contours of the cross sections of the aft fuselage leads to a decrease in the upward deflection of the flow by the aft part of the fuselage, which, in turn, leads to a decrease in the unevenness of the flow bevels behind the aircraft and, as a consequence, to a decrease in the aerodynamic (inductive) resistance and increase in aerodynamic quality at cruising flight modes.

In fig. Figure 1 shows the prototype fuselage, showing the streamlines flowing around its aft part and the streamlines behind the aircraft wing.

In fig. Figure 2 shows the distribution of flow slopes along the wingspan behind an aircraft with a prototype fuselage.

In fig. Figure 3 shows the inventive fuselage, showing the streamlines flowing around its rear part and the streamlines behind the aircraft wing.

In fig. Figure 4 shows the distribution of flow slopes along the wing span behind an aircraft with the proposed fuselage.

In fig. Figure 5 shows the aft fuselage of the TVRS-44 passenger aircraft model and its modification in accordance with the claimed design of the aft fuselage.

In fig. Figure 6 shows a comparison of the experimental values of the aerodynamic quality of the TVRS-44 aircraft model with the original and modified aft fuselage.

The inventive aircraft fuselage includes a nose part 1, a middle part 2 mating with the root part of the aircraft wing 3, and a rear part 4, made with a bend upward relative to the horizontal fuselage (see Fig. 3. The aft part of the fuselage is made with cross sections having convex external contours 10 with kinks 11 at the point of intersection of the lower surface of the aft part with the vertical plane of symmetry of the fuselage, see Fig. 3. The breaks in the external contours of the cross sections of the aft fuselage are made with angles 12 in the range from 180° to 30° on the inside of the sectional contours, see Fig. 3.

The claimed change in the cross-sectional shape of the aft fuselage makes it possible to reduce the upward deflection of the flow and streamlines 13 flowing around the aft fuselage, see FIG. 3, which leads to a convergence of the flow directions behind the wing 14 and the fuselage 13, a decrease in the unevenness 15 of the distribution of flow bevels 16 along the wing span behind the aircraft, see FIG. 4 and, as a consequence, a reduction in the inductive drag of the aircraft and an increase in aerodynamic quality.

To test the effectiveness of the proposed solution, TsAGI carried out tests in a wind tunnel on a model of a light passenger aircraft TVRS-44 with the original and proposed aft fuselage. In the original version of the model, the cross sections had a round shape, and the inventive aft part was made with kinks at the point of intersection of the lower surface of the aft part with the vertical plane of symmetry of the fuselage, see Fig. 5. The test results showed an increase in the aerodynamic quality of the proposed model compared to the original one by ΔКmax = 0.4–0.5, see Fig. 6.

Claims (2)

1. An aircraft fuselage, including a nose part, a middle part mating with the root part of the aircraft wing, and an aft part made with a bend upward relative to the construction horizontal of the fuselage, and convex outer contours of the cross sections, characterized in that the lower parts of the outer contours of the cross sections of the aft the parts are made with a break at the point of their intersection with the vertical plane of symmetry of the fuselage. 2. The aircraft fuselage according to claim 1, characterized in that the fracture angles of the lower parts of the external contours of the cross sections of the aft fuselage on the inner side of the contour are made in the range from 180° to 30°.