RU208563U1 - AIRCRAFT PROTECTION PANEL - Google Patents

Abstract

The utility model relates to rocket and space technology and concerns structural elements of slab thermal protection of the fuselage, wings, stabilizers and other structural elements of an aircraft (LA). The protective panel of the aircraft consists of ceramic tiles, which are glued to the surface of the aircraft with a heat-resistant adhesive together with an individual elastic substrate, with thermal gaps between the edges of the tiles. Thermal gaps are completely filled with elastic heat-resistant material. The tiles are in the form of rectangular prisms. In this case, the bases of the tiles are displaced relative to each other in the direction of one of the diagonals of the base of the tiles. On top of each tile, a thin-walled protective shell made of a heat-resistant composite material is pressed with a coefficient of thermal expansion the same as that of the tile material. EFFECT: increased strength of the aircraft heat-shielding coating and reduced probability of its separation from the hull skin. 4 ill.

Description

The utility model relates to rocket and space technology: structural elements of the fuselage heat shield, wings, stabilizers and other structural elements of the aircraft.

The closest analogue is the protective panel of the Buran spacecraft (see https://www.buran.ru/htm/tersaf.h).

The thermal protection of the aircraft during descent is exposed to strong heating and high dynamic loads. Upon entering the atmosphere, the maximum loads are valid for approximately 10 minutes. The lower and large parts of the side surfaces of the aircraft are heated to 100 ° C, acoustic loads reach 165 dB, vibrations reach 35 Hz / inch.

The entire lower part and side surfaces of the aircraft are protected by reusable thermal protection in the form of lightweight ceramic tiles with a low coefficient of thermal expansion, glued together with an individual elastic backing to the aircraft body.

Basically, the tiles are in the shape of a rectangular prism, along with this, there are tiles of special shapes and sizes. The size of the tiles depends on the size of the thermal gap and is limited by the strength under thermal and mechanical stress. Most of the tiles have a top and bottom edge of 150 × 150 mm. The thickness of the tiles depends on the heating temperature of the aircraft body. On the most heat-stressed lower part of the aircraft, the thickness of the tiles is: at the nose 32-58 mm, in the middle part 50-55 mm, in the tail 60-72 mm.

The tiles are made of ceramic material based on silicon dioxide fibers.

Thermal expansion coefficient 5 · 10 ^-7 1 / deg

The material can withstand heating temperatures up to 1250 ° С

Specific weight of TZMK-25 tiles 0.25 g / cm ³

Compressive strength 1.8 MPA

A special coating is applied to the top and side edges of the tiles, which gives the tiles strength and protects them from atmospheric precipitation. To carry out gas exchange inside the tile during takeoff and descent of the aircraft, this coating retreats from the bottom of the side edges by 5 mm.

The tiles are mounted on the aircraft body with gaps between the edges. The size of the gap is determined by the size of the expansion of the tile during heating, as well as the amount of deformation of the body from the action of static and dynamic loads. The main size of the gap on the lower parts of the aircraft is 1 mm, on the upper parts - 1.4 mm, the tolerance is +/- 0.4 mm.

The gaps between the tiles are filled with a heat-resistant ceramic filament cloth, which crumples and spreads out.

The tiles are glued to the body through an elastic synthetic felt backing. It reduces the stresses in the tiles during deformation of the structure.

To fasten the layers of the heat-protective coating to each other (tile + felt) and the entire element of the heat-protective coating to the skin (felt + covering), we used Elastosil 137-175M adhesive-sealant with an operating temperature range from minus -130 ° C to + 300 ° C.

Disadvantages of analog

1. The ceramic material from which the tiles are made is heat-resistant and lightweight, but has little strength, which makes it very difficult to operate the aircraft.

2. The special coating applied to the tiles:

burns out from the action of high temperatures,

short-lived

increases the strength of the tile insufficiently.

3. The protective panel of the aircraft mainly consists of tiles in the form of rectangular prisms, while the tiles are not interconnected and there is a high probability of their separation in flight from the effects of high air flow pressures, vibrations, twists and bends of the aircraft body.

The technical problem arising from criticism of the analogue is to increase the strength of the tiles and reduce the likelihood of their separation from the aircraft body.

Due to the fact that the tiles have a large thickness, the specified technical problem is solved by the fact that the tiles, instead of shapes in the form of rectangular prisms, have the shape of regular inclined prisms, the bases of which are displaced relative to each other in the direction of one of the diagonals, while on top of each tile is pressed a thin-walled protective shell made of a heat-resistant composite material with the same coefficient of thermal expansion as that of the tile material. For the implementation of gas exchange inside the tile during takeoff and descent of the aircraft, the height of the side edges of the shell is less than that of the tile itself.

The advantage of the proposed coverage also includes the following:

the side faces of adjacent tiles overlap, thereby increasing their peel strength;

the specific pressure on the inclined side faces is less due to their larger area with the same tile thickness;

the depth of the thermal gap is greater, which increases the thermal resistance;

when repairing tiles, it is not difficult to replace with a new one;

the shape of the tile allows it to be well laid on curved surfaces;

when laying tiles on a cylindrical surface, only one of its facets is cut;

for a plane and a cylindrical surface, the square shape of the tiles is preferable, for narrow flat surfaces - rhombic.

The claimed utility model is shown in Fig. 1-2 and photos 1, 2.

FIG. 1 shows a protective panel.

FIG. 2 shows a part of the protective panel, shows the tile in plan and its section.

FIG. 1, fig. 2 indicates:

1 - protective panel;

2 - aircraft skin;

3 - tiles;

4 - gap;

5 - tile shell;

6 - elastic backing;

7 - offset of the lateral surface of the shell from the lower plane of the tile.

The protective panel (1) is designed to provide thermal protection of the aircraft skin (2), the tiles (Z) protect the aircraft skin from thermal loads, the gap (4) is designed to compensate for the thermal expansion of the tiles, the shell (5) gives the tiles strength and improves their performance characteristics, the elastic substrate (6) reduces stresses in the tile during deformation of the aircraft body, the indent (7) is designed to carry out gas exchange inside the tile during takeoff and descent of the aircraft.

For clarity, a mock-up of the protective panel of the aircraft was made, which is shown in photographs 1 and 2.

The model has dimensions of 1000 × 700 mm. The surface to be protected has a cylindrical shape with a radius of 4 m. The tiles are made of solid foam. The size of the tiles is 150 × 150 mm and the thickness is 50 mm. The upper base of the tiles is offset from the lower by 50 mm. For dense tile laying, one edge was slightly trimmed. The tiles were glued to the surface at a distance.

Unfastened tiles adhere well to the nests, but have the ability to exit at an angle to the surface of the coating.

Claims (1)

The protective panel of the aircraft consists of ceramic tiles in the form of rectangular prisms, which are glued to the surface of the aircraft with heat-resistant glue together with an individual elastic substrate, with thermal gaps between the edges of the tiles, completely filled with elastic heat-resistant material, characterized in that the bases of the tiles are offset relative to each other the other in the direction of one of the diagonals of the tile base, while on top of each tile a thin-walled protective shell made of a heat-resistant composite material with the coefficient of thermal expansion is the same as that of the tile material is pressed.

Images