GB2120991A - Tail structure for ground effect vehicle - Google Patents

Abstract

A tail structure for a ground effect vehicle or an aerofoil boat of the catamaran type has two tail fins (11,12) and a tail plane (13) connecting the tail fins. This tail structure also serves as a radar antenna shroud and as launching tubes for antiaircraft missiles without substantially increasing the drag, weight and costs of the vehicle, launching tubes (14, 15) for antiaircraft missiles being incorporated as a structural part of each tail fin (11,12), and a radar antenna shroud (13a) being incorporated as a structural part of the tail plane (13). <IMAGE>

Description

SPECIFICATION Tail structure for ground effect vehicle The invention relates to a tail structure for a ground effect vehicle or an aerofoil boat having two parallel hulls, a centre wing connecting the two hulls and a tail structure connecting the hulls rearwardly ofthe centre wing, said tail structure comprising a tail fin rising from each hull and a tail plane connecting the tail fins.

A problem is involved in providing a radar in high-speed low-flying vehicles of this type. Thus, in orderto obtain maximum range of a radar at low heightoratsea level, high wavelengths beams should be used, since such beams followthe curvature of the earth surface betterthan beams having a short wavelength However, such long-wave beams require a:larg e lbrge diametre ofthe antenna, which constitutes a problem fora vehicle travelling at extremely high speed, sincethe antenna shroudwill create a large drag.

If such low-flying high-speed vehicles are attacked by airplanes, it is reasonableto supposethatthe airplanes will preferably attackfrom behind. It is therefore desirable to provide launching tubes for antiaircraft missiles, which may be fired in a slanting direction upwards and rearwards. However, the launching trajectory for such missiles may easily be obstructed by a radarantenna shroud ata high level.

At the sametime it is important in such vehiclesto avoid heavystructures reducing the payload of the vehicle and/orprnviding additional drag The objectofthe present invention isto provide a tail structure for a vehicle of the type referred to above, which structure isdesigned so aslargelyto solvethe above mentioned problems.

According to the invention launchingtubesfor antiai rcrafrmissiles are incorporated as a structural part of eachtail fin, while a radarantenna shroud is incorporated as a structural partofthetail plane.

The radar antenna shroud, v which is discus-shaped, preferablyiforms the centre portion ofthetail plane, whereasthe lateral portions ofthetail plane on either side ofthe shroud slope gently downwards from the lower side ofthe shroudtowardsthetail fins. The launclhingtubes in the tail fins may have approximatelythe same inclination as the leading edge ofthe tail fits. Furthermore, the launching tubes preferably pass through the hulls and open onto the lower side ofthe vehicle.

The centre discus-shaped radar antenna shroud can accomodate a rotating radar antenna with associated driving gear etc. The two lateral portions of the tail plane are connected to the centre shroud at the level of the lower side thereof and slope downwards to preventtheirmasses unnecessarily to impedethe effectiveness of the radar.

Several launching tubes for target seeking missiles and diverting heat sources, respectively, can be incorporated in each tail fin. The missiles may for instance be ofthetype Bofors Robot 70. The launching tubes open onto the lowersideofthevehicleto preventtoo large reaction forces and heat strains on the vehicle.

The drawing illustrates an embodimentof a ground effect vehicle having a tail structure according to the invention.

Fig. is a plan view of the vehicle.

Fig. 2 is a sectional view along the line Il-Il in Fig. 1.

Fig. 3 shows the vehicle seen from the front.

As illustrated in the drawing the vehicle may consist of two hulls 1 and 2, a centre wing 3, two side wings 4 and 5, a tail structure 6 and a canard wing 7 carrying turbofan engines 8 and 9.

The vehicle is intended for operation at low speeds at such a low heightthat sharp keel portions of the hulls 1 and 2 dip into the water, and at high speeds (up to 200 to 300 km/h) at a height above the water level of a few metres with possibilities fortemporarily rising to heights of 20 to 30 m.

Atail structure 6 according to the invention consists oftwotail fins 11 and 12 and a tail plane 13 comprising a centre discus-shaped shroud 1 3a and lateral portions 13b and 13cwhich slope gently downwardsfrom the lower side of the discus-shaped shroud 13a towards and preferably somewhat beyond the tail fins 11 and 12to which the lateral portions of the tail plane are connected. Thetail planeofthetail structure according to the invention thus serves two functions, partly serving as a shroudforthe radar antenna, partly carrying outthe usual function of a tail plane, namely serving as a stabiliser in the vertical plane.

As shown in Fig.2 launching tubes 14 and 15for targetseeking antiaircraft missiles and diverting heat sources, respectively, are provided in the tail fins 11 and 12. These launching tubes 14 and 15 constitute an integral structural part of the tail fin.

Inthis mannerthe launching tubes may be given a suitable inclination without contributing at all to an increased drag or weight.

1. Tail structure for a ground effect vehicle or an aerofoil boat having two parallel hulls (1,2), a centre wing (3) connecting the two hulls and a tail structure (6) connecting the hulls rearwardly ofthe centre wing, such tail structure comprising a tail fin (11, 12) rising from each hull and a tail plane(13) connecting thetail fins, characterized in that launching tubes (14, 15) for antiaircraft missiles are incorporated as a structural part of each tail fin (11,12), and that a radar antenna shroud (13a) is incorporated as a structural part ofthe tail plane(13).

2. Tail structure according to claim 1, characte rized in that the radar antenna shroud (13a), which is discus-shaped,formsthecentre portion of the tail plane, and thatthe lateral portions (13b, 1 3c) ofthe tail plane on either side of the shroud (13a) slope gently downwards from the lower side of the shroud (1 3a) towards thetail fins (11,12).

3. Tail structure according to claim 1 or 2, characte rized in that the lau nching tubes (14,15) have approximately the same inclination as the leading edge of the tail fins (11,12).

4. Tail structure according to any of the preceding claims, characterized in that the launching tubes (14, 15) passthrough the hulls (1,2) and open onto the lower side of the vehicle.

5. Atail structure for a ground effect vehicle or aerofoil boat substantially as hereinbefore described with reference to the drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Tail structure for ground effect vehicle The invention relates to a tail structure for a ground effect vehicle or an aerofoil boat having two parallel hulls, a centre wing connecting the two hulls and a tail structure connecting the hulls rearwardly ofthe centre wing, said tail structure comprising a tail fin rising from each hull and a tail plane connecting the tail fins. A problem is involved in providing a radar in high-speed low-flying vehicles of this type. Thus, in orderto obtain maximum range of a radar at low heightoratsea level, high wavelengths beams should be used, since such beams followthe curvature of the earth surface betterthan beams having a short wavelength However, such long-wave beams require a:larg e lbrge diametre ofthe antenna, which constitutes a problem fora vehicle travelling at extremely high speed, sincethe antenna shroudwill create a large drag. If such low-flying high-speed vehicles are attacked by airplanes, it is reasonableto supposethatthe airplanes will preferably attackfrom behind. It is therefore desirable to provide launching tubes for antiaircraft missiles, which may be fired in a slanting direction upwards and rearwards. However, the launching trajectory for such missiles may easily be obstructed by a radarantenna shroud ata high level. At the sametime it is important in such vehiclesto avoid heavystructures reducing the payload of the vehicle and/orprnviding additional drag The objectofthe present invention isto provide a tail structure for a vehicle of the type referred to above, which structure isdesigned so aslargelyto solvethe above mentioned problems. According to the invention launchingtubesfor antiai rcrafrmissiles are incorporated as a structural part of eachtail fin, while a radarantenna shroud is incorporated as a structural partofthetail plane. The radar antenna shroud, v which is discus-shaped, preferablyiforms the centre portion ofthetail plane, whereasthe lateral portions ofthetail plane on either side ofthe shroud slope gently downwards from the lower side ofthe shroudtowardsthetail fins. The launclhingtubes in the tail fins may have approximatelythe same inclination as the leading edge ofthe tail fits. Furthermore, the launching tubes preferably pass through the hulls and open onto the lower side ofthe vehicle. The centre discus-shaped radar antenna shroud can accomodate a rotating radar antenna with associated driving gear etc. The two lateral portions of the tail plane are connected to the centre shroud at the level of the lower side thereof and slope downwards to preventtheirmasses unnecessarily to impedethe effectiveness of the radar. Several launching tubes for target seeking missiles and diverting heat sources, respectively, can be incorporated in each tail fin. The missiles may for instance be ofthetype Bofors Robot 70. The launching tubes open onto the lowersideofthevehicleto preventtoo large reaction forces and heat strains on the vehicle. The drawing illustrates an embodimentof a ground effect vehicle having a tail structure according to the invention. Fig. is a plan view of the vehicle. Fig. 2 is a sectional view along the line Il-Il in Fig. 1. Fig. 3 shows the vehicle seen from the front. As illustrated in the drawing the vehicle may consist of two hulls 1 and 2, a centre wing 3, two side wings 4 and 5, a tail structure 6 and a canard wing 7 carrying turbofan engines 8 and 9. The vehicle is intended for operation at low speeds at such a low heightthat sharp keel portions of the hulls 1 and 2 dip into the water, and at high speeds (up to 200 to 300 km/h) at a height above the water level of a few metres with possibilities fortemporarily rising to heights of 20 to 30 m. Atail structure 6 according to the invention consists oftwotail fins 11 and 12 and a tail plane 13 comprising a centre discus-shaped shroud 1 3a and lateral portions 13b and 13cwhich slope gently downwardsfrom the lower side of the discus-shaped shroud 13a towards and preferably somewhat beyond the tail fins 11 and 12to which the lateral portions of the tail plane are connected. Thetail planeofthetail structure according to the invention thus serves two functions, partly serving as a shroudforthe radar antenna, partly carrying outthe usual function of a tail plane, namely serving as a stabiliser in the vertical plane. As shown in Fig.2 launching tubes 14 and 15for targetseeking antiaircraft missiles and diverting heat sources, respectively, are provided in the tail fins 11 and 12. These launching tubes 14 and 15 constitute an integral structural part of the tail fin. Inthis mannerthe launching tubes may be given a suitable inclination without contributing at all to an increased drag or weight. CLAIMS

1. Tail structure for a ground effect vehicle or an aerofoil boat having two parallel hulls (1,2), a centre wing (3) connecting the two hulls and a tail structure (6) connecting the hulls rearwardly ofthe centre wing, such tail structure comprising a tail fin (11, 12) rising from each hull and a tail plane(13) connecting thetail fins, characterized in that launching tubes (14, 15) for antiaircraft missiles are incorporated as a structural part of each tail fin (11,12), and that a radar antenna shroud (13a) is incorporated as a structural part ofthe tail plane(13).

2. Tail structure according to claim 1, characte rized in that the radar antenna shroud (13a), which is discus-shaped,formsthecentre portion of the tail plane, and thatthe lateral portions (13b, 1 3c) ofthe tail plane on either side of the shroud (13a) slope gently downwards from the lower side of the shroud (1 3a) towards thetail fins (11,12).

3. Tail structure according to claim 1 or 2, characte rized in that the lau nching tubes (14,15) have approximately the same inclination as the leading edge of the tail fins (11,12).

4. Tail structure according to any of the preceding claims, characterized in that the launching tubes (14, 15) passthrough the hulls (1,2) and open onto the lower side of the vehicle.

5. Atail structure for a ground effect vehicle or aerofoil boat substantially as hereinbefore described with reference to the drawings.