Method for managing in-flight refuelling of a fleet of aircraft

• US 20040182966A1
• Filed: 12/03/2003
• Published: 09/23/2004
• Est. Priority Date: 06/08/2001
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Morin, Dominique, Schneider, Catherine
• Granted Patent: US 6,832,743 B2
• Time in Patent Office: Days
• US Class Current: 244/13
• CPC Class Codes: B64D 39/00 Refuelling during flight filling or emptying fuel tanks B64D37/14
• CPC Class Codes: G08G 5/0052 for cruising combined instruments indicating more than one navigational value G01C23/00

Abstract

The in-flight refuelling of a squadron (1) of aircraft by a tanker (2) by means of the same refuelling hose requires the formation of a queue and the determination of the number of passes, one or possibly two, by each aircraft to the refuelling hose, which constitutes a refuelling sequence. Although the order in the queue is simple to establish, since it often corresponds to a classification by decreasing quantities of fuel demanded, the same does not apply to the number of passes to the refuelling hose, which must be minimized while still respecting the endurances of the aircraft to be refuelled before their actual refuelling starts. The method described, which may be implemented by a computer, automates the search for a refuelling sequence that satisfies the endurance requirements of the various aircraft to be refuelled, while still having the minimum number of passes to the refuelling hose by the aircraft in the squadron.

Claims

1. A method of managing the in-flight refuelling of a squadron (1) of n aircraft A1, . . . , An from the same refuelling hose of a tanker (2), making it possible to generate a refuelling sequence on the basis of taking into account a refuelling rendezvous point P, the number n of aircraft in the squadron (1), the amounts of fuel Q1, . . . , Qn demanded by the aircraft A1, . . . , An of the squadron (1) and the maximum distances L1, . . . , Ln that can be covered by each aircraft in the squadron (1) in waiting for the start of refuelling, these maximum distances L1, . . . , Ln corresponding to the distances separating the refuelling rendezvous point P, over the route followed by the tanker (2), from the limiting points that can be reached by the various aircraft in the squadron (1) without refuelling and without them drawing on their fuel reserves, said method being characterized in that it comprises the following steps:

of initially taking an arbitrary refuelling sequence defined by the queuing of the aircraft in the squadron (1) in an arbitrary order A1, . . . , An and a single pass by each aircraft in the squadron (1) to the refuelling hose;

of testing the viability of the refuelling sequence adopted, consisting in expressing, as distances D1, . . . , Dn to be flown by the tanker (2), the times needed to deliver to the aircraft in the squadron (1) the planned amounts of fuel during their passes to the refuelling hose and in verifying, by going down the queue, that each aircraft other than the one at the front of the queue A2, . . . , An will start its refuelling within the deadlines, that is to say before the tanker (2) has flown a distance greater than the maximum distance L2, . . . , Ln that can be covered by the aircraft in question;

when there is no finding that an aircraft will start its refuelling beyond the deadline, of accepting the viability of the refuelling sequence tested and of adopting it;

when there is a finding that an aircraft will start its refuelling beyond the deadline, of modifying the refuelling sequence tested in order to shorten the waiting time by this aircraft and of trying to fuel it within the deadlines, the modification in the sequence consisting in dividing, into two passes, the refuelling operation or operations of one or more aircraft that precede the aircraft in question in the queue, a first shortened pass to the refuelling hose allowing an aircraft to receive a minimum amount of fuel, increasing its endurance sufficiently for it to be able to move to the end of the queue and to wait for a second pass to the refuelling hose for the remainder of the fuel without drawing on its fuel reserve, the one or more aircraft whose refuelling is divided into two being chosen so as to minimize the number of passes to the refuelling hose, the choice firstly depending on the aircraft, if there is one, that is placed ahead in the queue and the dividing of the refuelling of which into two passes to the refuelling hose makes it possible to approach as best as possible, by an upper value, the desired time saving, and then on the two aircraft, if they exist, placed ahead in the queue, the divisions of the refuelling of which make it possible to approach as best as possible, by an upper value, the desired time saving, and so on, the absence of a solution in the choice of the aircraft for divided refuelling resulting in a finding that it is impossible to refuel the entire squadron, whereas the presence of a solution leads to a modified refuelling sequence proposal; and

of taking any modified refuelling sequence proposal and testing its viability by restarting at the second step of the method.

2. The method as claimed in claim 1, characterized in that it includes an additional step in the case of a negative viability test of the arbitrary refuelling sequence initially adopted, this step consisting in replacing said arbitrary refuelling sequence with a refuelling sequence referred to as a nominal refuelling sequence defined by an order in the queue corresponding to decreasing amounts of fuel demanded and by a single pass of each aircraft in the squadron (1) to the refuelling hose, the first aircraft in the queue being that requiring the largest amount of fuel.

3. The method as claimed in claim 1, characterized in that it includes an additional step in the case of a negative viability test of the arbitrary refuelling sequence initially adopted, this step consisting in replacing said arbitrary refuelling sequence with a refuelling sequence defined by an order in the queue corresponding to increasing maximum distances L1, L2 . . . , Ln that can be covered and by a single pass by each aircraft in the squadron (1) to the refuelling hose, the aircraft placed at the front of the queue being that having the shortest maximum distance that can be covered.

4. The method as claimed in claim 1, characterized in that, should a viability test of a refuelling sequence be negative owing to the finding that one aircraft in the squadron (1) will start its refuelling beyond the deadline, the choice of the one or more aircraft, placed ahead in the queue, the refuelling of which is divided, results from systematic virtual tests carried out by going up the queue taking into consideration one aircraft, then two aircraft, including that one giving the greatest time saving, then three aircraft, including the two providing the greatest time saving, and so on.

5. The method as claimed in claim 1, characterized in that the duration of a first shortened pass to the refuelling hose of a divided refuelling operation is set to the same value DMIN for all the aircraft in the squadron (1), which value is progressively increased, once the refuelling sequence has satisfied the viability test, until reaching the endurance limit for one of the aircraft in the squadron (1).

6. The method as claimed in claim 1, characterized in that the choice of the aircraft in the squadron (1) whose refuelling is divided results from checking that a succession of inequality relationships between the flight distances D1, . . . , Dn needed by the tanker (2), in order to deliver the required amounts of fuel during each pass of the aircraft in the squadron (1) to the refuelling hose and the maximum distances L1, L2, . . . , Ln that can be covered by each aircraft in the squadron (1), is met.

7. The method as claimed in claim 1, applied to a squadron of two aircraft, characterized in that it consists:

in accepting an arbitrary order in the queue for the two aircraft in the squadron;

in checking whether the maximum distance L2 that can be covered by the aircraft in second position in the refuelling queue is greater than the duration, expressed as a distance D1 that can be covered, necessary for refuelling the aircraft placed in first position in the queue in one pass to the refuelling hose;

if this is the case, since the condition D1<

L2 is satisfied, in adopting the refuelling sequence D1, D2 with only one pass per aircraft to be refuelled; and

if this is not the case, since the condition D1<

L2 is not satisfied, in checking that the maximum distance L2 that can be covered by the aircraft placed second in the queue is greater than the minimum duration, expressed as the distance DMIN that can be covered, of a pass to the refuelling hose;

if this is not the case, since the condition DMIN<

L2 is not satisfied, in signaling the impossibility of refuelling with the adopted order in the queue; and

if this is the case, since the condition D1<

L2 is satisfied, in adopting the refuelling sequence D11, D2, D12 with the refuelling of the aircraft at the front of the queue being divided into two passes.

8. The method as claimed in claim 7, characterized in that the duration of the first refuelling pass D11 by the aircraft in first position in the queue is taken as equal to the maximum distance L2 that can be covered by the aircraft placed in second position in the queue.

9. The method as claimed in claim 1, applied to a squadron of three aircraft, characterized in that it consists:

in accepting an order in the refuelling queue for the three aircraft in the squadron corresponding to decreasing amounts of fuel demanded;

in checking whether the maximum distances L2 and L3 that can be covered by the aircraft placed in the second and third positions in the queue are greater than the durations D1, D1+D2, expressed as distances that can be covered, of the refuelling in one pass to the refuelling hose of the one or more aircraft that is or are placed ahead in the queue;

if this is the case, since the conditions D1<

L2 and D1+D2<

L3 are satisfied, in adopting the refuelling sequence D1, D2, D3 with only one pass to the refuelling hose per aircraft to be refuelled;

if this is not the case, since at least one of the conditions D1<

L2 or D1+D2<

L3 is not satisfied, in checking that the maximum distances L2, L3 that can be covered by the aircraft not occupying the front of the queue are greater than the minimum durations, expressed as the distance DMIN that can be covered, of a pass to the refuelling hose by each of the aircraft placed ahead in the queue;

if this is not the case, since one of the conditions DMIN<

L2 or 2DMIN<

L3 is not satisfied, in signaling the impossibility of refuelling with the adopted order in the queue;

if this is the case, since both the conditions DMIN<

L2 and 2DMIN<

L3 are satisfied, in searching for the refuelling operation(s) the dividing of which leads to a refuelling sequence making it possible to commence the refuelling of all the aircraft in the squadron before they have flown their maximum distances that can be covered while still having only the minimum number of passes to the refuelling hose;

said search for the refuelling operation(s) to be divided in order to be able to commence the refuelling of the aircraft before they have flown their maximum distances that can be covered comprising the following successive steps;

checking whether the conditions D1<

L2 and D1+DMIN<

L3 are fulfilled;

if this is the case, adopting the refuelling sequence D1, D21, D3, D22 with only the refuelling of the aircraft placed in second position in the queue being divided into two passes;

if this is not the case, since one of the conditions D1<

L2 or D2+DMIN<

L3 is not satisfied, checking whether the condition D2+DMIN<

L3 is fulfilled;

if the condition D2+DMIN<

L3 is fulfilled, adopting the refuelling sequence D11, D2, D3, D12 with only the refuelling of the aircraft at the front of the queue being divided into two passes; and

if the condition D2+DMIN<

L3 is not fulfilled, adopting the refuelling sequence D11, D21, D3, D12, D22 with the refuelling of the aircraft placed in first and second positions in the queue being divided into two passes.

10. The method as claimed in claim 9, characterized in that, upon completing the selection of the refuelling sequence D1, D21, D3, D22 with only the refuelling of the aircraft in second position in the queue being divided into two passes, the duration of the first refuelling pass by the aircraft placed in second position in the queue, expressed as the distance D21, is taken as equal to the maximum distance L3 that can be covered by the aircraft placed at the back of the queue, reduced by the distance D1 necessary for refuelling the aircraft placed at the front of the queue in one pass:

D21=L3−

D1

the duration of the second refuelling pass by the aircraft placed in second position in the queue, expressed as the distance D22, being taken as equal to the duration necessary for the amount of fuel transferred in total to reach the amount demanded;

D22=D2−

D21.

11. The method as claimed in claim 9, characterized in that, upon completing the selection of the refuelling sequence D11, D2, D3, D12 with only the refuelling of the aircraft in first position in the queue being divided into two passes, the duration of the first refuelling pass by the aircraft placed in first position in the queue, expressed as the distance D11, is taken as equal to the minimum of the maximum distance L2 that can be covered by the aircraft placed in second position in the queue and of the maximum distance L3 that can be covered by the aircraft placed in third position in the queue, reduced by the distance D2 necessary for refuelling the aircraft placed in second position in the queue in one pass:

D11=min(L2, L3−

D2)

the duration of the second refuelling pass by the aircraft placed in the first position in the queue, expressed as the distance D12, being taken as equal to the duration necessary for the amount of fuel transferred in total to reach the amount demanded;

D12=D1−

D11.

12. The method as claimed in claim 9, characterized in that, upon completing the selection of the refuelling sequence D11, D21, D3, D12, D22 with the refuelling of the aircraft placed in the first and second positions in the queue being divided into two passes, the durations of the first refuelling passes by the aircraft placed in the first and second positions in the queue, expressed as the distances D1, D21, are taken as equal to the duration DMIN increased iteratively by an increment INC until, as a limit, the situation is reached in which the conditions D11<

L2 and D11+D21<

L3 imposed by the endurances of the aircraft placed in the second and third positions in the queue are met, the durations of the second refuelling passes by the aircraft placed in the first and second positions in the queue, expressed as distances D12, D22 being taken as equal to the durations necessary for the amounts of fuel transferred in total to reach the amounts demanded;

D12=D1−

D11 and D22=D2−

D21.

13. The method as claimed in claim 1, applied to a squadron of four aircraft, characterized in that it consists:

in accepting an order in the refuelling queue for the four aircraft in the squadron corresponding to decreasing amounts of fuel demanded;

in checking whether the maximum distances L2, L3 and L4 that can be covered by the aircraft placed in the second, third and fourth positions in the queue are greater than the durations D1, D1+D2, D1+D2+D3 expressed as distances that can be covered, of the refuelling in one pass to the refuelling hose of the one or more aircraft that is or are placed ahead in the queue;

if this is the case, since the conditions D1<

L2, D1+D2<

L3 and D1+D2+D3<

L4 are satisfied, in adopting the refuelling sequence D1, D2, D3, D4 with only one pass per aircraft to be refuelled;

if this is not the case, since at least one of the conditions D1<

L2 or D1+D2<

L3 or D1+D2+D3<

L4 is not satisfied, in checking that the maximum distances L2, L3, L4 that can be covered by the aircraft not occupying the front of the queue are greater than the minimum durations, expressed as the distance DMIN that can be covered, of a pass to the refuelling hose by each of the aircraft placed ahead in the queue;

if this is not the case, since one of the conditions DMIN<

L2 or 2DMIN<

L3 or 3DMIN<

L4 is not satisfied, in signaling the impossibility of refuelling with the adopted order in the queue;

if this is the case, since the three conditions DMIN<

L2, 2DMIN<

L3 and 3DMIN are satisfied, in searching for the refuelling operation(s) the dividing of which leads to a refuelling sequence making it possible to commence the refuelling of all the aircraft in the squadron before they have flown their maximum distances that can be covered while still having only the minimum number of passes to the refuelling hose;

said search for the refuelling operation(s) to be divided in order to be able to commence the refuelling of the aircraft before they have flown their maximum distances that can be covered comprising the following successive steps;

checking whether the conditions D1<

L2 and D1+D2<

L3 and D1+D2+DMIN<

L4 are fulfilled;

if this is the case, adopting the refuelling sequence D1, D2, D31, D4, D32 with only the refuelling of the aircraft placed in third position in the queue being divided into two passes;

if this is not the case, since one of the conditions D1<

L2 or D1+D2<

L3 or D1+D2+DMIN<

L4 is not fulfilled, checking whether the conditions D1<

L2, D1+DMIN<

L3 and D1+D3+DMIN<

L4 are fulfilled;

if this is the case, adopting the refuelling sequence D1, D21, D3, D4, D22 with only the refuelling of the aircraft placed in second position in the queue being divided into two passes;

if this is not the case, since one of the conditions D1<

L2 or D1+DMIN<

L3 or D1+D3+DMIN<

L4 is not fulfilled, checking whether the conditions D2+DMIN<

L3 and D2+D3+DMIN<

L4 are fulfilled;

if this is the case, adopting the refuelling sequence D11, D2, D3, D12 with only the refuelling of the aircraft placed in first position in the queue being divided into two passes;

if this is not the case, since one of the conditions D2+DMIN<

L3 or D2+D3+DMIN<

L4 is not fulfilled, checking whether the conditions D1<

L2, D1+DMIN<

L3 and D1+2DMIN<

L4 are fulfilled;

if this is the case, adopting the refuelling sequence D1, D21, D31, D4, D22, D32 with the refuelling of the aircraft placed in second and third positions in the queue being divided into two passes;

if this is not the case, since one of the conditions D1<

L2 or D1+DMIN<

L3 or D1+2DMIN<

L4 is not fulfilled, checking whether the conditions D2+DMIN<

L3 and D2+2DMIN<

L4 are fulfilled;

if this is the case, adopting the refuelling sequence D11, D2, D31, D4, D12, D32 with the refuelling of the aircraft placed in first and third positions in the queue being divided into two passes;

if this is not the case, since one of the conditions D2+DMIN<

L3 or D2+2DMIN<

L4 is not fulfilled, checking whether the condition D3+2DMIN<

L4 is fulfilled;

if the condition D3+2DMIN<

L4 is fulfilled, adopting the refuelling sequence D11, D21, D3, D4, D12, D22 with the refuelling of the aircraft placed in first and second positions in the queue being divided into two passes; and

if the condition D3+2DMIN<

L4 is not fulfilled, adopting the refuelling sequence D11, D21, D31, D4, D12, D22, D31 with the refuelling of the aircraft placed in first, second and third positions in the queue being divided into two passes.

14. The method as claimed in claim 13, characterized in that, upon completing the selection of the refuelling sequence D1, D2, D31, D4, D32 with only the refuelling of the aircraft in third position in the queue being divided into two passes, the duration of the first refuelling pass by the aircraft placed in third position in the queue, expressed as the distance D31, is taken as equal to the maximum distance L4 that can be covered by the aircraft placed at the back of the queue, reduced by the distances D1 and D2 necessary for refuelling the aircraft placed in first and second positions in the queue in one pass:

D31=L4−

D1−

D2

the duration of the second refuelling pass by the aircraft placed in third position in the queue, expressed as the distance D32, being taken as equal to the duration necessary for the amount of fuel transferred in total to reach the amount demanded;

D32=D3−

D31.

15. The method as claimed in claim 13, characterized in that, upon completing the selection of the refuelling sequence D1, D21, D3, D4, D22 with only the refuelling of the aircraft in second position in the queue being divided into two passes, the duration of the first refuelling pass by the aircraft placed in second position in the queue, expressed as the distance D21, is taken as equal to the minimum of the maximum distance L4 that can be covered by the aircraft placed at the back of the queue, reduced by the distances D1 and D3 necessary for refuelling the aircraft placed in first and third positions in the queue in one pass, and of the maximum distance L3 that can be covered by the aircraft placed in third position in the queue, reduced by the distance D1 necessary for refuelling the aircraft placed at the front of the queue in one pass:

D21=min(L3−

D1, L4−

D1−

D3)

the duration of the second refuelling pass by the aircraft placed in second position in the queue, expressed as the distance D22, being taken as equal to the duration necessary for the amount of fuel transferred in total to reach the amount demanded;

D22=D2−

D21.

16. The method as claimed in claim 13, characterized in that, upon completing the selection of the refuelling sequence D11, D2, D3, D4, D12 with only the refuelling of the aircraft in first position in the queue being divided into two passes, the duration of the first refuelling pass by the aircraft placed in first position in the queue, expressed as the distance D11, is taken as equal to the minimum of the maximum distance L2 that can be covered by the aircraft placed in second position in the queue, of the maximum distance L4 that can be covered by the aircraft placed at the front of the queue, reduced by the distances D2 and D3 necessary for refuelling the aircraft placed in second and third positions in the queue in one pass, and of the maximum distance L3 that can be covered by the aircraft placed in third position in the queue, reduced by the distance D2 necessary for refuelling the aircraft placed in second position in the queue in one pass:

D11=min(L2, L3−

D2, L4−

D2−

D3)

the duration of the second refuelling pass by the aircraft placed in first position in the queue, expressed as the distance D12, being taken as equal to the duration necessary for the amount of fuel transferred in total to reach the amount demanded;

D12=D1−

D11.

17. The method as claimed in claim 13, characterized in that, upon completing the selection of the refuelling sequence D1, D21, D31, D4, D22, D32 with the refuelling of the aircraft in second and third positions in the queue being divided into two passes, the durations of the first refuelling passes by the aircraft placed in second and third positions in the queue, expressed as the distances D21, D31, are taken as equal to the duration DMIN increased iteratively by an increment INC until, as a limit, the situation is reached in which the conditions D1+D21<

L3 and D1+D21+D31<

L4 imposed by the endurances of the aircraft placed in third and fourth positions in the queue are met, the durations of the second refuelling passes by the aircraft placed in second and third positions in the queue, expressed as distances D22, D32, being taken as equal to the durations necessary for the amounts of fuel transferred in total to reach the amounts demanded;

D22=D2−

D21 and D32=D3−

D31.

18. The method as claimed in claim 13, characterized in that, upon completing the selection of the refuelling sequence D11, D2, D31, D4, D12, D32 with the refuelling of the aircraft placed in first and third positions in the queue being divided into two passes, the durations of the first refuelling passes by the aircraft placed in first and third positions in the queue, expressed as the distances D11, D31, are taken as equal to the duration DMIN increased iteratively by an increment INC until, as a limit, the situation is reached in which the conditions D11<

L2, D11+D2<

L3 and D11+D2+D31<

L4 imposed by the endurances of the aircraft placed in the second, third and fourth positions in the queue are met, the durations of the second refuelling passes by the aircraft placed in first and third positions in the queue, expressed as the distances D12, D32, being taken as equal to the durations necessary for the amounts of fuel transferred in total to reach the amounts demanded;

D12=D1−

D11 and D32=D3−

D31.

19. The method as claimed in claim 13, characterized in that, upon completing the selection of the refuelling sequence D11, D21, D3, D4, D12, D22 with the refuelling of the aircraft placed in first and second positions in the queue being divided into two passes, the durations of the first refuelling passes by the aircraft placed in first and second positions in the queue, expressed as the distances D11, D21, are taken as equal to the duration DMIN increased iteratively by an increment INC until, as a limit, the situation is reached in which the conditions D11<

L2, D11+D21<

L3 and D11+D21+D3<

L4 imposed by the endurances of the aircraft placed in second, third and fourth positions in the queue are met, the durations of the second refuelling passes by the aircraft placed in the first and third positions in the queue, expressed as the distances D12, D32, being taken as equal to the durations necessary for the amounts of fuel transferred in total to reach the amounts demanded;

D12=D1−

D11 and D22=D2−

D21.

20. The method as claimed in claim 13, characterized in that, upon completing the selection of the refuelling sequence D11, D21, D31, D4, D12, D32 with the refuelling of the aircraft placed in the first, second and third positions in the queue being divided into two passes, the durations of the first refuelling passes by the aircraft placed in the first, second and third positions in the queue, expressed as the distances D11, D21, D31, are taken as equal to the duration DMIN increased iteratively by an increment INC until, as a limit, the situation is reached in which the conditions D11<

L2, D1+D21<

L3 and D11+D21+D31<

L4 imposed by the endurances of the aircraft placed in the second, third and fourth positions in the queue are met, the durations of the second refuelling passes by the aircraft placed in the first, second and third positions in the queue, expressed as the distances D12, D22, D32, being taken as equal to the durations necessary for the amounts of fuel transferred in total to reach the amounts demanded;

D12=D1−

D11, D22=D2−

D21 and D32=D3−

D31.