Soft removable thermal shield for a missile seeker head

A soft removable thermal shiled for protecting a heat-sensitive element of a projectile. The shield includes a main body and an attachment arrangement forconnecting the main body to the projectile. The main body is designed to cover part of a window of the projectile, behind which the element is disposed. The main body is designed also to thermally protect the element during part of the flight of the projectile, and to be soft enough when released from the projectile, so that the main body does not harm the projectile after it is released.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to a thermal shield and, in particular, it concerns a soft removable thermal shield for a seeker head of a guided missile.

By way of introduction, some guided missiles have an internal seeker head which is disposed behind a window, which is located at the nose of the missile. Typically, the seeker head and often the window itself are sensitive to heat exposure, which is caused by friction of the missile body with air during supersonic or hypersonic flight. This heat exposure can result in breakage to the window and damage to the seeker head. Additionally, the seeker head is typically not used for the entire flight, but only during the terminal phase of the flight. Therefore, the window of the missile should be covered by a thermal protector during the first phases of the flight while the seeker head is not used.

One prior art thermal protector is a rigid thermal protector which covers the window during the first phases of the flight and which is retracted from the window during the terminal phase of the flight. A shortcoming of this thermal cover is its cost and mechanical complexity.

Another prior art thermal protector is a rigid thermal protector which covers the window during the first phases of the flight and which is released completely from the missile at the beginning of the terminal phase of the flight. This thermal cover is less costly and mechanically simpler than the first prior art thermal cover. A shortcoming of this thermal cover is that when this thermal cover is released it may hit the real part of the missile, thereby causing damage to the missile.

There is therefore a need for an inexpensive thermal shield for a missile seeker that does not damage the missile when released.

SUMMARY OF THE INVENTION

The present invention is a soft removable thermal shield for a guided missile seeker head and a method of operation thereof.

According to the teachings of the present invention there is provided, a soft removable thermal shield for protecting a heat-sensitive element of a projectile, comprising: (a) a main body configured to: (i) cover at least part of a window of the projectile, the element being disposed behind the window; (ii) thermally protect the element during at least part of a flight of the projectile; and (iii) be sufficiently soft upon being released from the projectile during the flight that the main body is substantially harmless to the projectile after being released; and (b) an attachment arrangement for releasably connecting the main body to the projectile.

According to a further feature of the present invention the main body includes an ablative material.

According to a further feature of the present invention the ablative material is ablative rubber.

According to a further feature of the present invention, there is also provided: (c) a reinforcement of the main body.

According to a further feature of the present invention the reinforcement includes at least one layer of textile fabric.

According to a further feature of the present invention, there is also provided: (c) a protective layer that is disposed adjacent to the window when the main body is operationally connected to the projectile, wherein a coefficient of friction between the protective layer and the window is sufficiently low to allow the main body to release substantially easily from the window and to leave the window substantially clean of a residue of the main body.

According to a further feature of the present invention the protective layer includes at least one layer of glass fiber fabric.

According to a further feature of the present invention the attachment arrangement includes at least one cord, the at least one cord having two ends, one of the ends being configured for attachment to the main body, and another of the ends being configured for attachment to the projectile.

According to a further feature of the present invention the attachment arrangement includes at least one cord, the at least one cord having two ends and a middle section, at least part of the middle section being mechanically connected to the main body, each of the two ends being configured for attachment to the projectile.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is a soft removable thermal shield construction and method of operation thereof.

The principles and operation of the soft removable thermal shield according to the present invention may be better understood with reference to the drawings and the accompanying description.

Reference is now made to FIG.1and FIG.2.FIG. 1is a schematic view from above of a horizontally flying projectile10, specifically a guided missile, having a soft removable thermal shield12, disposed on the nose section18thereof, that is constricted and operable in accordance with a preferred embodiment of the present invention.FIG. 2is a cross-sectional view taken along line2—2of FIG.1. Thermal shield12has a main body14and an attachment arrangement16. Nose section18includes a window20. Within projectile10and behind window20is an element22, for example a seeker head, which is sensitive to thermal exposure. Main body14is configured to cover window20and to thermally protect element22and window20during the initial part of the flight of projectile10. Main body14is also configured to be sufficiently soft, upon release from projectile10during the flight, that main body14is substantially harmless to projectile10after being released. The softness of main body14takes into account the relative velocities of main body14and projectile10after the release of main body14from projectile10. In particular main body14is substantially harmless to the tail section24of projectile10. In accordance with a preferred embodiment of the present invention main body14is inherently soft. In accordance with a most preferred embodiment of the present invention main body14is initially relatively rigid but becomes soft during the flight, for example, by being formed from an ablative material such as ablative rubber whereby main body14is thick and hard at the beginning of the flight but enough of main body14ablates during the flight so that main body14is soft when released. It should be noted that an ablative material, such as ablative rubber, provides thermal protection to element22and window20, as the ablative material absorbs heat by ablating. Attachment arrangement16is configured to operationally connect main body14and projectile10prior to the release.

Reference is now made toFIG. 3, which is a detailed cross-sectional view of main body14and projectile10of thermal shield12of FIG.1. Main body14typically includes an outer layer26of reinforced ablative material, typically ablative rubber, which is reinforce by one or more layers28of textile fabric. Outer layer26faces away from window20when main body14is operationally connected to projectile10. Therefore outer layer26and reinforcement layers28provide a flexible, soft thermal protection. In accordance with a preferred embodiment of the present invention, thermal shield12also includes at least one protective layer30, typically formed from glass fiber fabric. Protective layer30forms an inner layer of main body14, such that, protective layer30is disposed adjacent to window20when main body14is operationally connected to projectile10. The coefficient of friction between protective layer30and window20is sufficiently low to allow main body14of thermal shield12to release substantially easily from window20and to leave window20substantially clean from a residue of main body14. Attachment arrangement16includes at least one cord32. In accordance with a most preferred embodiment of the present invention, cord32has two ends34,36and a middle section38. Part of middle section38is mechanically connected to main body14, typically by sandwiching middle section38between layers28and protective layer30. End34and end36are configured for attachment to projectile10. Methods of attaching attachment arrangement16to projectile10and releasing therefrom are known to those skilled in the art.

Reference is now made toFIG. 4, which is a detailed cross-sectional view of main body14and an alternate attachment arrangement16of thermal shield12of FIG.1. In accordance with an alternate preferred embodiment of the present invention, attachment arrangement16has at least two cords40,42. Cord40has two ends44,46. Cord42has two ends48,50. Ends44,48are mechanically connected to main body14, typically by sandwiching ends44,48between layers28and protective layer30. End46and end50are configured for attachment to projectile10.