Method of jettisoning an external load carried by an aircraft, and an associated device

1. A method of automatically jettisoning an external load ( 4 ) suspended reversibly from a release-hook ( 12 ) of an aircraft fuselage ( 2 ) by means of a sling ( 13 ) liable to extend at an angle (θ) of varying magnitude relative to a vertical axis in elevation (AX) of the aircraft ( 1 ) parallel to the yaw axis (Z) of the aircraft ( 1 ) and passing via a connection point ( 100 ) connecting support means ( 11 ) for the release-hook ( 12 ) to the fuselage ( 2 ) of the aircraft ( 1 ), the method comprising:

measuring said angle (θ); and

activating automatic jettisoning when firstly said angle (θ) exceeds an upper bound (BSUP), and secondly said sling ( 13 ) is directed towards the rear ( 4 ′) of the aircraft thereby making it possible, optionally, to proceed with jettisoning said external load ( 4 ).

2. A method according to claim 1 , wherein, when said angle (θ) lies between a lower bound (BINF) and said upper bound (BSUP), a first alarm is triggered.

3. A method according to claim 1 , wherein a first value (V 1 ) is determined for a quotient (Q) of a tension (T) exerted on the sling ( 13 ) as divided by an evaluation term (N) that depends on a load factor (n) of said fuselage ( 2 ) along and a gravity axis (P), and a second value (V 2 ) is determined for the time derivative

(

ⅆ

Q

ⅆ

t

)

of said quotient (Q).

4. A method according to claim 3 , wherein said evaluation term (N) is equal to said load factor (n).

5. A method according to claim 3 , wherein said evaluation term (N) is equal to the product of said load factor (n) multiplied by an acceleration due to gravity (g).

6. A method according to claim 3 , wherein a second alarm is triggered when firstly automatic jettisoning is not activated as a result of said angle (θ), and when secondly said first and second values (V 1 , V 2 ) reach respective predetermined levels.

7. A method according to claim 3 , wherein automatic jettisoning is triggered by ordering said release-hook ( 12 ) to release said sling ( 13 ) when firstly automatic jettisoning is activated as a result of said angle (θ), and when secondly said first and second values (V 1 , V 2 ) reach respective predetermined levels.

8. A method according to claim 3 , wherein automatic jettisoning is triggered by ordering the release-hook ( 12 ) to release said sling ( 13 ) when firstly automatic jettisoning is activated as a result of said angle (θ), and when secondly said first value (V 1 ) exceeds an upper limit (LSUP), independently of the value of said second value (V 2 ).

9. A method according to claim 3 , wherein automatic jettisoning is triggered by ordering the release-hook ( 12 ) to release said sling ( 13 ) when firstly automatic jettisoning is activated as a result of said angle (θ), and secondly said first value (V 1 ) lies between a lower limit (LINF) and an upper limit (LSUP) and said second value (V 2 ) exceeds a threshold (S).

10. An aircraft ( 1 ) provided with an attachment device ( 10 ) for attaching an external load ( 4 ) to a fuselage ( 2 ) of the aircraft ( 1 ), said attachment device ( 10 ) being provided with a release-hook ( 12 ), with support means ( 11 ), and with a sling ( 13 ), said the release-hook ( 12 ) being fastened to an attachment point ( 100 ) for attaching to the fuselage ( 2 ) by the support means ( 11 ), said sling ( 13 ) being secured reversibly to said the release-hook ( 12 ) and being liable to extend at an angle (θ) relative to a vertical axis in elevation (AX) of the aircraft parallel to a yaw axis (Z) of the aircraft ( 1 ) and passing via an attachment point ( 100 ) for attaching said support means ( 11 ) for the release-hook ( 12 ) to the fuselage ( 2 ) of the aircraft, wherein the aircraft includes measurement means ( 30 ) for determining said angle (θ), and a processor unit ( 20 ) connected to said release-hook ( 12 ) and to said measurement means ( 30 ), said processor unit ( 20 ) being suitable for receiving a first signal (S 1 ) from the measurement means ( 30 ) relating to said angle and to the position of the sling, so as to implement the automatic jettisoning method according to claim 1 .

11. An aircraft according to claim 10 , wherein said measurement means ( 30 ) are provided with an arch ( 31 ) arranged on said support means ( 11 ) and with a sensor ( 32 , 33 ) suitable for being arranged on said fuselage ( 2 ).

12. An aircraft according to claim 11 , wherein said sensor is provided with a movable paddle ( 32 ) and with an angle sensor ( 23 ) for determining the position of said paddle ( 32 ).

13. An aircraft according to claim 10 , wherein said attachment device comprises a load cell ( 22 ) arranged on said support means ( 11 ), said load cell ( 22 ) being connected to said processor unit ( 20 ) to send thereto a second signal (S 2 ) relating to the tension (T) of said sling ( 13 ).

14. An aircraft according to claim 10 , wherein said attachment device ( 10 ) includes an accelerometer ( 21 ) connected to said processor unit ( 20 ) to send thereto a first signal (S 3 ) relating to the accelerations to which said fuselage ( 2 ) is subjected so as to enable the processor unit ( 20 ) to determine a first value of (V 1 ) for a quotient (Q) of the tension (T) exerted on the sling ( 13 ) as divided by an evaluation term the depends on the load factor (n) of said fuselage ( 2 ) along the gravity axis (P), and a second value (V 2 ) for the time derivative

(

ⅆ

Q

ⅆ

t

)

of said quotient (Q).

15. An aircraft according to claim 10 , wherein said attachment device ( 10 ) includes a display unit ( 40 ) controlled by the processor unit ( 20 ) to display alarms and/or information relating to the attachment operation.

16. An aircraft according to claim 10 , wherein said attachment device ( 10 ) includes manual control means ( 50 ) for controlling the release-hook ( 12 ).