Device for controlling bird strike hazards

BACKGROUND OF THE INVENTION

The invention relates to means for dispersing birds in airport regions.

Birds are a real nuisance to airports. They cause considerable delays or even accidents on take-off if they are ingested into an aircraft jet engine running at full power. Combating the threat posed by birds is therefore a major problem to airports.

There are known, for example, electronic systems installed near the take-off and landing strips, which emit signals at frequencies likely to scare the birds by imitating the cries of predators. However, birds living close to the airport become accustomed to these electronic systems which therefore become ineffective.

Elsewhere, use is also made of conventional hunting cartridges. The drawback of this means lies in the fact that the hunting cartridge is only low range, about 50 m, and that it is noisy at the start of the shot. The birds can therefore locate the firing device by the noise at the beginning of the firing and keep away from it without actually vacating the at-risk areas of the airport.

At lightly used airports, use is also made of specially trained falcons from falconries in order to keep birds away from the airport. However, this technique of combating the threat caused by birds cannot be applied to airports where the aerial traffic is intense.

SUMMARY OF THE INVENTION

The invention aims to alleviate these drawbacks by creating an acoustic-effect pyrotechnic device intended to scare birds over some distance, and which has no acoustic signature at the start.

To this end, the subject of the invention is a pyrotechnic device for combating the threat caused by birds, characterized in that it consists of a self-propelled projectile containing a propulsion motor and an element for the delayed ignition of an acoustic-effect charge intended to scare birds and which is housed in the said projectile.

BRIEF DESCRIPTION OF THE DRAWING

Other features and advantages of the invention will become clear from the following description which is given by way of non-limiting example, with reference to the appended drawing, in which:

FIG. 1

is a view in longitudinal section of a pyrotechnic device against the threat caused by birds, according to the invention, and

FIG. 2

is a view in longitudinal section of an alternative form of the pyrotechnic device according to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1

depicts a pyrotechnic device for combating the threat caused by birds according to the invention, comprising a case

1

of cylindro-ogival shape connected by its open end to a base

3

comprising a motor

5

.

The case

1

and the base

3

delimit a housing

7

containing an acoustic-effect charge

9

intended to scare birds.

The base

3

has a cylindrical overall external shape and on the same side as the housing

7

has a smaller diameter cylindrical extension

10

which project into this housing

7

and is surrounded by the acoustic-effect charge

9

.

The base

3

also comprises, on the opposite side to the extension

10

, an axial well

11

in which the motor

5

is housed, and an axial duct

12

intended to house a composition for the delayed ignition of the acoustic effect charge

9

. This duct

12

extends through the extension

10

to open at one end into the housing

7

and at its other end communicates with the axial well

11

.

The motor

5

comprises a nozzle

13

housed at the opposite end of the well

11

to the extension

10

and fixed into the base

3

by crimping, bonding or screwing. This nozzle

13

comprises a percussion or electric detonator

15

, depending on the type of launcher used.

Delimited between the nozzle

13

and the end of the well

11

close to the extension

10

is a combustion chamber

16

which communicates on the nozzle

13

side with the detonator

15

. The opposite end of the well

11

to the detonator

15

accommodates a dish

17

containing a composition

18

for initiating the motor

5

. Radially, the combustion chamber

16

is delimited by a solid propellant

19

in the form of a hollow cylinder in contact with the initiation composition

18

.

Furthermore, the end of the dish

17

has a hole

21

at its centre.

The delayed-ignition composition consists of a pyrotechnic delay

27

which fills the duct

12

over more or less three-quarters of its length and which is in contact with the initiation composition

18

through the hole

21

.

In the continuation of the pyrotechnic delay

27

and in contact therewith, an ignition composition

29

fills the remaining quarter of the duct

12

. On its other side, close to the acoustic-effect charge

9

, it is produced in the form of a firing space conventionally used in pyrotechnics.

Advantageously, the case

1

, the base

3

and the nozzle

13

are made of plastic, for example of the filled polyethylene type (PA 6.6) or of the polypropylene type, so as not to damage the blades of a jet engine should the debris of such a projectile accidentally be ingested into an aircraft jet engine.

The projectile according to the invention is intended to be fired from an individual weapon, for example a pistol of calibre

4

fitted with a reducing adapter or from a launcher that has a barrel suited to the calibre of the projectile and is long enough to provide the projectile with good guidance, and a device for firing the detonator

15

. For this, the base

3

, at its end that bears the nozzle

13

, has two lateral studs

31

made of plastic which hold the projectile in the launcher used.

The pyrotechnic device for combating the threat caused by birds according to the invention works as follow. When firing from a launcher designed for this purpose, first of all the detonator

15

is initiated. This initiation brings about ignition by projecting the fire from the detonator through the combustion chamber

16

to the initiation composition

18

which in turn ignites the propellant

19

and the pyrotechnic delay

27

.

Under the effect of the thrust obtained by the combustion of the propellant

19

, the studs

31

are broken and release the projectile which is propelled with a ballistic trajectory predetermined by the firer. As the pyrotechnic device travels, the pyrotechnic delay

27

is burnt up during a predetermined time until it in turn initiates the ignition composition

29

which finally causes the acoustic-effect charge

9

to explode. Through the acoustic effect of the deflagration, the birds towards which the projectile was fired are dispersed.

Advantageously, the quantities of pyrotechnic delay

27

and of propellant

19

are determined such that the pyrotechnic delay

27

initiates the acoustic-effect charge

9

via the ignition composition

29

.

The range of such a pyrotechnic device may be as much as 400 meters, depending on the amount of propellant.

By virtue of the propulsion motor, the launch of the projectile is not audible from a distance and cannot therefore be located early on by the birds. In consequence, the exploding of the acoustic-effect charge has an effect of surprise on the birds which can therefore effectively be driven away from the at-risk areas of the airport.

FIG. 2

presents an alternative form of pyrotechnic device for combating the threat caused by birds. Those elements which correspond to those of the pyrotechnic device depicted in

FIG. 1

have been denoted by the same reference numerals.

This alternative form can be differentiated from the pyrotechnic device depicted in

FIG. 1

in that the propulsive charge

19

itself forms the element for delayed ignition of the acoustic-effect charge

9

.

To this end, the axial well

11

of the base

3

is longer than the one in

FIG. 1 and

, at the same end as the acoustic-effect charge

9

, has a cylindro-ogival shape. This axial well

11

communicates by the opposite end to the nozzle

13

with the housing

7

containing the acoustic-effect charge

9

by a passage

33

. Incidentally, the base

3

in the alternative form has no extension projecting into the housing

7

.

According to the alternative form, the solid propellant

19

hugs the wall of the base delimiting the axial well

11

, and is in contact with the acoustic-effect charge

9

through the passage

33

. The solid propellant

19

is hollowed at its centre at the same end as the nozzle

13

to approximately three-quarters of the way along its length, thus forming an elongate combustion chamber

16

. At the opposite end of the chamber

16

to the nozzle there is a composition

18

for initiating the propellant

19

, for example an ignition enhancer. It will thus be understood that the axial well

11

in its cylindro-ogival-shaped part that lies between the initiation composition

18

and the passage

33

is completely filled with propellant

19

.

The way in which the pyrotechnic device depicted in

FIG. 2

works is similar to the operation of the pyrotechnic device depicted in FIG.

1

.

In effect, when firing from a launcher designed for this purpose, first of all the detonator

15

is initiate his initiation brings about ignition by projecting the fire from the detonator through the combustion chamber

16

to the initiation composition

18

which in turn ignites the propellant

19

.

Under the effect of the thrust obtained by the combustion of the propellant

19

, the studs

31

are broken and release the projectile which is propelled in the direction of a region at which the gunner is aiming. As the pyrotechnic device travels, the propellant

19

is burnt up. When the propellant

19

that lies between the initiation composition

18

and the surface for contact with the acoustic-effect charge

9

has been burnt up, the acoustic-effect charge

9

is initiated in turn and explodes. Thus, the birds towards which he projectile was fired are dispersed.

It will be understood that the delay between launching the pyrotechnic device and the exploding of the acoustic-effect charge

9

is determined by the distance D between the initiation composition

18

and the propellant/acoustic-effect charge contact surface.