DE3246190A1 - Tank protection system in aircraft - Google Patents

Abstract

The invention relates to a tank protection system in aircraft against hammer-shock effects when fired at, the vulnerability of the aircraft being reduced, without adversely affecting the fuel capacity, by the ability to form intermediate spaces, which can be flooded or ventilated, between the tank bay internal wall and the fuel filling said tank.

Description

Tank protection system in aircraft

The invention relates to a tank protection system in aircraft against Hamm shock effects in case of fire.

In the case of tank rooms in integral construction, the sealed aircraft cell is At the same time, the fuel tank and, in the case of CFRP shell construction, is the cell skin load-bearing structure and accordingly also stressed.

If projectiles or projectile fragments penetrate, the creates a tension wave in the outer skin, which is superimposed with the basic tension and at the same time a shock wave is generated by the impact on the tank liquid, which propagates in the liquid at the speed of sound or supersonic speed.

The high rigidity - incompressibility - of the fluid transfers extremely high pressure loads on the outer skin surrounding the penetration point and aircraft structure opposite in the direction of the projectile (- inlet -) and becomes disastrous if the structure is immediately wetted with fuel Structural damage and fuel leakage.

The invention is now based on the object of a tank protection system of the type mentioned above, which significantly reduces the vulnerability of the aircraft reduced without this having a notable impairment of the fuel capacity or the weight of the aircraft.

This task is accomplished by the measures laid down in the claims solved in a surprisingly reliable way. In the following description are Embodiments dealt with and shown schematically in the drawing.

1 shows a schematic cross section for demonstration purposes of the principle, Fig. 2 shows a tank cross-section in the fuselage structure of an aircraft.

Fig. 1 graphically illustrates the principle explained at the outset, such as it happens when projectiles or projectile fragments hit, splinters, etc. carries out. It follows from this that the pulse energy from these projectiles etc. must be destroyed as quickly as possible in order to avoid serious aircraft damage to avoid. The very stiff, little deformable CFRP outer skin can do this not or only hardly meet, so that the fuel take over this energy conversion must and can do this relatively well. At the point of penetration it must now be prevented that the shock and pressure wave can rest directly on the outer skin. Therefor cignet is the application of a thin, closed, fuel-resistant, air-filled Damping layer.

The energy is generated by reflections at the liquid boundary layer distributed and the pressure wave elastically absorbed by the intermediate layer. These thin, firm damping layer guarantees at the same time that after a short, fixed Penetration stage the fragment hits liquid and the impulse energy conversion can use.

For this purpose, it is filled between the inner wall of the tank space 10a and the Propellant 11 formed an intermediate space 12 which can be flooded or ventilated. The or the Spaces 12 are located both on the inner edge of the outer skin 10b as well as around the so-called engine inlet 13. To form said intermediate spaces 12 different possibilities are now given. So can such - as already said - by a closed, thin, fuel-resistant damping layer 12a be formed, or by means of an open-cell foam with a final Outer skin.

But also cloth-like membrane surfaces or correspondingly flexible tank skins sirid is also suitable for this, as are fiber composite shells.

The advantage of this protection device is that it hardly ever consumes any fuel displaced during refueling and thus maximum tank utilization and flight range guaranteed.

When the combat zone is reached, fuel has already been consumed and the fuel displaced when the protective device is activated is not lost, i.e.

at the beginning of a mission flight, the aircraft can almost completely match the previous one Take up the tank filling and the approach will be necessary for the use of the protective device required free space automatically due to the fuel consumption that has taken place in the meantime educated.

The separating layer on the side opposite the penetration point should be inflatable to keep fuel loss low and for cushioning the head and pressure wave to have a slightly thicker separating layer available. This membrane wall is useful to prevent the fuel from being carried by rising gas bubbles loses its maximum energy absorption.

In the case of wing tanks, it is advisable to place them on the inside of the tank and on the underside of the wing either c ine closed, air-filled damping layer or a cushioning pad that can be inflated if required.

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Claims (4)

Tank protection system in aircraft Patent claims 1. Tank protection system in aircraft against hammer shock effects when bombarded, thus g e k e n n -z e i c h n e t that between the tank space inner wall (10a) and the filled fuel (11) flood or. ventable intermediate spaces (12) are formed. 2. Tank protection system according to claim 1, characterized in that g e -k e n n z e i. c h n e t that the intermediate space (12) by means of a thin, closed, fuel-resistant Damping layer (12a) is formed. 3. Tank protection system according to claim 1, characterized in that g e -k e n n z e i c h n e t that the space (12) closed by an open-cell foam with Outer skin is formed. 4. Tank protection system according to claim 1, characterized in that g e -k c n n z e i c h n e t that the intermediate space (12) by a cloth-like, flexible membrane surface is formed.