U.S. patent application number 12/551687 was filed with the patent office on 2014-04-24 for thrust reverser and nacelle for aircraft equipped with at least one such reverser.
This patent application is currently assigned to AIRBUS OPERATIONS. The applicant listed for this patent is Guillaume Poirier, Olivier Teulou. Invention is credited to Guillaume Poirier, Olivier Teulou.
Application Number | 20140110503 12/551687 |
Document ID | / |
Family ID | 40328783 |
Filed Date | 2014-04-24 |
United States Patent
Application |
20140110503 |
Kind Code |
A1 |
Teulou; Olivier ; et
al. |
April 24, 2014 |
THRUST REVERSER AND NACELLE FOR AIRCRAFT EQUIPPED WITH AT LEAST ONE
SUCH REVERSER
Abstract
A thrust reverser for a double-flow nacelle that has a cowling,
with the thrust reverser having an internal door and an external
door designed to be made within the thickness of the cowling. The
reverser also has means for simultaneously displacing the doors
between a first position called the rest position, in which the
doors are integrated into the cowling so as to form an aerodynamic
continuity with the external wall and the internal wall of the
cowling, and a second active position, in which the doors are open
so that the internal and external doors extend toward the inside
and toward the outside of the nacelle, respectively, thus at least
partially blocking the annular channel of the secondary flow, to
deflect the secondary flow and to generate a thrust reversal, with
the means being designed to be received in a compartment arranged
inside the cowling formed by the doors in the rest position.
Inventors: |
Teulou; Olivier; (Buzet Sur
Tarn, FR) ; Poirier; Guillaume; (Semussac,
FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Teulou; Olivier
Poirier; Guillaume |
Buzet Sur Tarn
Semussac |
|
FR
FR |
|
|
Assignee: |
AIRBUS OPERATIONS
Toulouse
FR
|
Family ID: |
40328783 |
Appl. No.: |
12/551687 |
Filed: |
September 1, 2009 |
Current U.S.
Class: |
239/265.19 |
Current CPC
Class: |
F02K 1/70 20130101; F02K
1/625 20130101; F02K 1/763 20130101; B64D 33/04 20130101 |
Class at
Publication: |
239/265.19 |
International
Class: |
F02K 1/62 20060101
F02K001/62 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 2, 2008 |
FR |
0804816 |
Claims
1. A thrust reverser for double-flow nacelle that has a cowling,
with said thrust reverser having an internal door and an external
door designed to be made within the thickness of said cowling, and
means for simultaneously displacing said doors between a first
position called the rest position, in which said doors are
integrated into said cowling so as to form an aerodynamic
continuity with the external wall and the internal wall of said
cowling, and a second active position, in which said doors are open
so that said internal and external doors extend toward the inside
and toward the outside of the nacelle, respectively, thus at least
partially blocking the annular channel of the secondary flow, to
deflect the secondary flow and to generate a thrust reversal,
wherein said means of displacement of said doors comprise means for
sliding along a shaft essentially parallel to the principal axis of
the nacelle, with the extremities of said means being designed to
be linked to pivot at one extremity of said doors, with each of the
doors being linked also to said shaft through at least two
intermediate pivoting arms whose extremities are hinged
respectively to the door and to the shaft so that the sliding of
said means along said shaft causes the displacement of the doors
between the two positions, and in that said means of displacement
are arranged relative to the doors so that they are made to be
received in a compartment in said cowling formed by the doors in
the rest position.
2. The thrust reverser pursuant to claim 1, wherein the external
door and the internal door have dimensions such that the forces
generated by the pressure P1 of the external flow applied to a
surface S.sub.1A of the external door and by the pressure P2 of the
secondary flow applied to a surface S.sub.2A of the internal door
lead to the exertion of forces on the doors in a direction tending
to maintain the doors in the rest position, which becomes a stable
position, with said surfaces S.sub.1A, and S.sub.2A being delimited
respectively by the free of the external door and of the internal
door and the pivot linkages of said doors with the extremities of
the arms.
3. The thrust reverser pursuant to claim 1, wherein said means of
sliding have a reversible ball nut held on an endless screw, said
nut being designed to be displaced longitudinally along said screw
between a position located on the upstream side of said screw in
which the doors are in the rest position, and a position located on
the downstream side of said screw in which the doors are in the
deployed position, with the extremities of said nut being linked to
pivot both at the extremity of the external door and at the
extremity of the internal door.
4. The thrust reverser pursuant to claim 3, wherein the screw has a
first extremity linked to a structural element of the nacelle
located on the downstream side of said nacelle and a second
extremity linked to a second structural element of the nacelle
located on the upstream side of said nacelle.
5. The thrust reverser pursuant to claim 3, further comprising a
motor designed to displace said nut along the screw.
6. The thrust reverser pursuant to claim 1, wherein said pivoting
arms are connecting rods.
7. A nacelle for double-flow engine comprising a cowling, an engine
mounted inside an internal volume of the cowling, and an annular
channel for the flow of a secondary flow arranged between the
engine and the cowling, with said nacelle being equipped with at
least one thrust reverser pursuant to claim 1 to form a reversed
flow from said secondary flow.
8. The nacelle pursuant to claim 7, wherein said thrust reversers
are arranged in said cowling by being arranged around an external
circumference of said cowling.
9. The nacelle pursuant to claim 8, further comprising four groups
of three thrust reversers each arranged around said circumference,
with said groups being diametrically opposed in pairs.
10. An aircraft equipped with at least one nacelle pursuant to
claim 7.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to and the benefit of
French Application No. 08 55880, filed Sep. 2, 2008, which is
incorporated herein by reference in its entirety.
BACKGROUND
[0002] The disclosed embodiments relate to a thrust reverser to
form a reverse flow from a secondary thrust flow in a double-flow
nacelle. The disclosed embodiments also relate to a nacelle for a
double-flow engine equipped with such a reverser for aircraft.
[0003] In general, the nacelle has a cowling in which there is an
engine. Air is drawn into the nacelle at a front extremity of said
nacelle, located at the forward part of the aircraft. The nacelle
ejects the absorbed air at high velocity toward the rear of the
aircraft. To permit forward motion of the aircraft, it is necessary
for the air mass passing through the nacelle to have a discharge
velocity higher than the intake velocity. The discharge velocity of
the air mass is increased by a known method inside the nacelle.
[0004] The air passing through the nacelle is composed of two
different flows. A first flow, called the primary flow, passes
through the engine. The primary flow is ejected directly out of the
nacelle from the rear of the engine. A second flow, called the
secondary flow, passes through an air passage channel before being
ejected out of the nacelle. This air passage channel is an annular
channel formed between an inside wall of the nacelle cowling and an
outside wall of the engine, and extends along said engine.
[0005] When the aircraft lands, mechanical brakes provide for
mechanical braking of said aircraft. However, once the aircraft is
on the ground it is known how to utilize thrust reversers in
addition to the mechanical brakes. The thrust reversers in
particular favor reducing the landing distance of the aircraft. The
landing distance of the aircraft means the distance traveled by the
aircraft between the moment the landing gear of the aircraft
touches the runway and the moment when the aircraft has completely
stopped on the runway. The thrust reversers deflect all or part of
the air flow ejected from the rear of the nacelle and eject it
toward the front of the aircraft. The reversers thus create an
aerodynamic drag and accordingly a braking force called the
"counterthrust," which contributes to the slowing of the
aircraft.
[0006] Thrust reversers with two pivoting doors made in the
thickness of the nacelle cowling are known as thrust reversers. The
doors are distributed over an outer circumference of the nacelle
cowling. The number of reversers may vary, depending on the
particular applications, and according to the method of mounting
the propulsion apparatus assembly on the aircraft. In the inactive
position the doors are closed, in other words they extend in an
extension of the cowling. In the active position, the doors are
open. A displacement of the doors is such that parts of the doors
then extend toward the outside of the nacelle in a direction
essentially perpendicular to a longitudinal axis of the nacelle.
Generally speaking, each of the two doors has a free extremity and
a pivoting extremity. By a free extremity is meant the extremity of
the door that describes motion in an arc when the door is displaced
from the closed position to the open position. By a pivoting
extremity is meant the extremity of the door on which the pivoting
axis is positioned. Thus, when the doors are open, the free
extremity of one of the two doors extends toward the interior of
the nacelle, thus at least partially blocking the air passage
channel. The flow of air is then blocked, and is evacuated to
outside the nacelle by an opening made by opening the second door
toward the outside of the nacelle, which deflects the flow of air
toward the front of the nacelle so as to produce a thrust
reversal.
[0007] The document FR 2 887 225 discloses a nacelle equipped with
thrust reversers. Each thrust reverser is equipped with an internal
door and an external door, with each of these doors having a unique
direction of displacement. These two directions of displacement are
opposed, so that when the thrust reverser is in the active
position, the external door sends the air flow blocked by the
internal door inside the nacelle, toward the front of the nacelle.
Locking mechanisms are provided to guarantee that no untimely
opening of the doors can occur while the aircraft is in flight.
[0008] One of the problems of the known reversers is the complexity
of the movable elements that constitute the door displacement
apparatus, so that there is a risk of more frequent failure.
Furthermore, these movable elements are arranged relative to the
door in such a manner that a portion of these elements is situated
outside the cowling of the nacelle, inducing aerodynamic
perturbations at the nacelle.
[0009] The thrust reversers with pivoting doors are also
questionable in principle since they can be opened in an untimely
manner. Actually, the secondary flow passes under pressure into the
air passage made between the inside wall of the cowling and the
outside wall of the engine. Also, the secondary flow exerts
pressure against the inside wall of the cowling and accordingly
also on the doors. Since the displacement of the doors is directed
toward the outside of the nacelle, the force exerted by the flow of
air against the inside wall of the cowling favors the opening of
the doors. The risk of untimely opening is all the greater when the
control mechanism fails. A locking apparatus is generally proposed
to block the doors while the airplane is in flight. However, such
an apparatus does not guarantee for certain the closing of the
doors; actually it can also become inoperative itself during
flight, and this supplementary apparatus also causes an increase in
the cost of manufacture and also in the weight of the nacelle
equipped with such a reverser.
[0010] In general, the currently proposed thrust reversers are
associated with burdensome maintenance and design constraints
linked to the risk of untimely opening in flight.
SUMMARY
[0011] The disclosed embodiments attempt to resolve the problems
exposed above by producing a thrust reverser that is simple in
design and in its mode of operation.
[0012] The purpose of the disclosed embodiments is accordingly to
propose a new thrust reverser with doors to deflect the secondary
flow to as to produce a thrust reversal that is simple in
structural terms and in kinematic terms to minimize its weight and
its manufacturing cost, while providing for complete integration in
the nacelle cowling, thus providing for suppression of the
aerodynamic perturbations that may be introduced by their
presence.
[0013] Another purpose of the embodiments disclosed herein is to
propose thrust reversers whose inactive position is a stable
position, with the doors remaining closed or closing automatically
when the control mechanism of the doors fails, in order not to
generate any risk of untimely opening when the airplane is in
flight.
[0014] To this end, the presently disclosed embodiments relate to a
thrust reverser for a double-flow nacelle that has a cowling, said
thrust reverser comprising an internal door and an external door
intended to be produced within the thickness of said cowling, and
means for simultaneously displacing said doors between a first
position called the rest position, in which said doors are
integrated in said cowling to form an aerodynamic continuity with
the outside wall and the inside wall of said cowling, and a second
active position in which said doors are open so that said internal
and external doors extend toward the inside and toward the outside,
respectively, of the nacelle, thus at least partially blocking the
annular secondary flow channel, to deflect the secondary flow and
produce a thrust reversal.
[0015] According to one or more embodiments, said means of
displacement of said doors comprise [0016] means for sliding along
a shaft essentially parallel to the principal axis of the nacelle,
with the extremities of said means being designed to be linked in a
pivoting manner to one extremity of said doors, [0017] each of the
doors being also linked to said shaft through at least two
intermediate pivoting arms whose extremities are hinged
respectively to the door and to the shaft, so that the sliding of
said means along said shaft entails the displacement of the doors
between the two positions, and said displacement means are arranged
relative to the doors so that they are designed to be received in a
compartment produced in said cowling formed by the doors in the
rest position.
[0018] According to at least one embodiment, the external and
internal doors have such dimensions that the forces generated by
the pressure P1 of the external flow applied to a surface S.sub.1A
of the external door and by the pressure P2 of the secondary flow
applied to a surface S.sub.2A of the internal door lead to exertion
of forces on the doors in a direction tending to keep the doors in
the stable inactive position, said surfaces S.sub.1A and S.sub.2A
being delimited respectively by the free extremity of the external
and internal doors, and the pivot linkage of said doors with the
extremity of the arms.
[0019] This particularly advantageous configuration confers very
stable positions on the doors. Thus, by way of illustration, in
case the means of displacement fail, the external and internal
doors are no longer able to be kept permanently in the closed
position by the means of displacement. When the doors tend to open
under the force exerted by the secondary flow and the external flow
at the nacelle, because of the system disclosed herein, the doors
are automatically returned to the closed position under the action
of the forces generated by the pressure applied to the doors
only.
[0020] According to an embodiment, said means of sliding comprise a
reversible ball nut held on an endless screw, said nut being
intended to be moved longitudinally along said screw between a
position on the upstream side of said screw, in which the doors are
in the rest position, and a position on the downstream side of said
screw, in which the doors are in the open position, with the
extremities of said nut being linked to pivot at the same time on
the extremity of the external door and on the extremity of the
internal door.
[0021] In a general way and in the rest of the description, the
upstream and downstream positions are defined relative to the
normal direction of circulation of the gases with direct
thrust.
[0022] According to an embodiment, said pivoting arms are hinged
connecting rods.
[0023] According to an embodiment, the screw has a first extremity
linked to a structural element of the nacelle located on the
downstream side of said nacelle, and a second extremity linked to
another structural element of the nacelle located on the upstream
side of said nacelle.
[0024] According to an embodiment, the reverser also has a motor
designed to displace said nut along the screw.
[0025] At least one embodiment also relates to a nacelle for a
double-flow engine comprising a cowling, an engine mounted in an
internal volume of the cowling, and an annular flow channel for a
secondary flow provided between the engine and the cowling, said
nacelle being equipped with at least one thrust reverser such as
that described above to form a reverse flow from said secondary
flow.
[0026] According to an embodiment, said thrust reversers are
provided in said cowing arranged around an external circumference
of said cowling.
[0027] In a particular example of an embodiment, the nacelle
comprises four groups of three thrust reversers arranged on the
external circumference, said groups being diametrically opposite
one another, two for two.
[0028] Finally, an aircraft equipped with at least one nacelle is
also the subject matter of the disclosed embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The aspects of the disclosed embodiments will be better
understood by reading the following description and examining the
Figures that accompany it. They are shown by way of example and do
not limit the disclosed embodiments in any way. The Figures
show:
[0030] FIG. 1: a schematic representation in longitudinal cross
section of a nacelle equipped with thrust reversers according to
the disclosed embodiments, said reversers being shown in both the
active position and the inactive position;
[0031] FIG. 2: a more detailed representation in longitudinal cross
section of 1 reverser from FIG. 1 in the inactive position;
[0032] FIG. 3: a more detailed representation in longitudinal cross
section of the reverser in the active position;
[0033] FIG. 4: an illustration of the forces generated by the
external flow and the secondary flow, respectively, on the external
door and on the internal door of the thrust reverser; and
[0034] FIG. 5: a schematic representation of the nacelle viewed
from the front equipped with four groups of three thrust reversers
pursuant to the disclosed embodiments in the open position.
DETAILED DESCRIPTION
[0035] FIG. 1 shows a double-flow nacelle 100 equipped with two
diametrically opposed reversers pursuant to an example of an
embodiment. For example, an aircraft may be equipped with two
nacelles 100, with each nacelle 100 being integral with the lower
surface of a wing of said aircraft.
[0036] The nacelle 100 is equipped with an external cowling 101 and
a superposed internal cowling 102, with the external cowling 101
covering the internal cowling 102. An engine 3 is arranged in an
internal volume 104 of the cowling 102.
[0037] The thrust reversers 300 are made on the external 101 and
internal 102 cowlings of the nacelle. In FIG. 1, the reversers are
shown in both the inactive position and the active position on the
nacelle, to illustrate the two possible positions of the reverser.
Of course, in the normal operation of the nacelle, when the nacelle
is in direct thrust or in reversed thrust, the two positions of the
doors cannot coexist; the thrust reversers are either in the closed
position or in the open position. Each thrust reverser 300 has two
doors, an external door 301 and an internal door 302. The external
door 301 is made within the thickness of the external cowling 101.
The internal door 302 is made within the thickness of the internal
cowling 102. The external and internal doors 301 and 302 of the
same thrust reverser 300 are located in the same area of the
nacelle. The same area of the nacelle means that the internal door
302 and the external door 301 of a thrust reverser 300 are
superposed.
[0038] Air penetrates through a forward extremity 106 of the
nacelle 100 and leaves the nacelle 100 through a rear extremity 107
of said nacelle opposite the forward extremity 106. A portion of
the entering air forms a primary flow of air passing through the
engine 3 before being ejected out of the nacelle 100. Another
portion of the entering air forms a secondary flow of air. This
secondary flow passes into an air passage channel 2 before being
ejected out of the nacelle 100. This air passage channel 2 is
arranged between an external wall 109 of the engine and an internal
wall 102 of the internal cowling.
[0039] In the case in which the thrust reverser is in the inactive
position, the secondary flow is evacuated through the rear
extremity 107 of the nacelle 100. The doors are closed, and they
extend in the extension of the external cowling 101 and of the
internal cowling 102 in which they are arranged respectively, so as
to form an aerodynamic continuity with the external wall and the
internal wall of said cowlings.
[0040] In the case in which the thrust reverser is in the active
position, the doors are open simultaneously, so that said internal
and external doors extend toward the inside and toward the outside,
respectively, of the nacelle. Thus the displacements to open the
internal door 302 and external door 301 of a thrust reverser 300
are in opposite directions. The internal door 302, when it is open,
has a free extremity 14 directed toward the external wall 109 of
the engine 3. By free extremity of the door is meant the extremity
opposite the hinged extremity of said door. The opening of the
internal door 302 then obstructs the air passage channel 2 through
which the secondary air flow is passing. This flow can no longer be
directed toward the rear extremity 107 of the nacelle 100 to be
ejected outside the nacelle.
[0041] The free extremity of the external door 301 is pointed
toward the exterior of the nacelle 100, thus revealing an opening
111 through which the secondary flow is expelled. In addition, the
external door 301 extends in a direction essentially perpendicular
to a longitudinal axis 4 of the nacelle 11. The external door thus
deflects the secondary flow to leave toward the front 106 of the
nacelle, thus generating a thrust reversal.
[0042] FIGS. 2 and 3 show in further detail a thrust reverser
pursuant to an embodiment showing it in the inactive position and
the active position, respectively.
[0043] The thrust reverser also has means for displacement
providing for the simultaneous displacement of the external and
internal doors of the same reverser, between a first inactive
position in which said doors are integrated in the cowling, and a
second active position in which said doors are open so that said
internal and external doors extend toward the inside and toward the
outside of the nacelle, respectively.
[0044] This means of displacement is composed of a smaller number
of movable elements than in the known reversers, thus providing for
kinematics that are simple to put into action.
[0045] In order not to perturb the aerodynamic profile of the
nacelle, and more precisely the flowing of the secondary and
external flow around the wall of the cowling, the movable elements
are arranged so that when the external and internal doors are in
the inactive position, they are lodged in a compartment 112 formed
by the external door 301 and the internal door 302.
[0046] In a particularly advantageous way, when the doors are open,
these elements are arranged relative to the doors so that they are
no longer in the path of the deflected secondary flow, so as not to
perturb the flowing of the secondary flow during the
reversed-thrust phase.
[0047] Each of the doors has a free extremity 13, 14 and an
opposite extremity 5, 6 that are linked to pivot on a nut 502. The
free extremity of the door means the extremity opposite the hinged
extremity of said door. Said reversible ball nut 502 is mounted on
an endless screw 503 that has a longitudinal axis essentially
parallel to the principal axis of the nacelle 4. Said nut is
designed to slide along the screw 503.
[0048] The external door 301 and internal door 302, respectively,
are each linked to the screw 503 through two intermediate arm
assemblies 401, 402. Each assembly has at least two arms. The
extremities 7, 9 of the arms are hinged, respectively, to the door
and to the shaft 503 so that the sliding of the nut along the screw
entails the displacement of the doors 301, 302 between the inactive
position in which they are closed and the active position in which
they are open. Said arms typically are hinged connecting rods.
[0049] The screw 503 has a first extremity linked to a fixed
structural element 11 of the nacelle located on the downstream side
of said nacelle and a second extremity linked to another fixed
structural element 12 of the nacelle located on the upstream side
of said nacelle.
[0050] In the inactive position of the thrust reverser 300, the nut
is in a position located on the upstream side of the screw 503, and
the external doors 301 and 302 [sic] extend in the extension of the
external cowling 101 and the internal cowling 102. When it is
desired to move the thrust reverser 300 into the active position,
the displacement of the nut is brought about by means of a motor
501. The displacement of the nut toward the downstream side of the
screw drives the pivoting extremities of the doors toward the
interior of the compartment 112. The arms 401, 402 are hinged on
the screw and the external door 301 and the internal door 320,
pushing the doors toward the exterior of the nacelle. The external
door 301 and the internal door 302 pivot at the location of the
pivot 7, 8, so that the external door 301 is then opened toward the
exterior of the nacelle and the internal door 302 is opened toward
the air passage channel 2.
[0051] Thus, to go from the inactive position to the active
position, the free extremities of the doors have described an arc
in the direction from the rear of the nacelle toward the front of
the nacelle. The dimension of the door and the distance of
displacement of the nut along the screw are designed so that the
internal door extends toward the interior of the nacelle in a
direction essentially perpendicular to the axis 4 of the nacelle,
to obstruct the air passage 2.
[0052] When the thrust reverser 300 returns to the inactive
position, the nut returns to its initial position, guiding the
doors 301, 302 into the closed position by the intermediation of
the pivots.
[0053] As shown in FIG. 4, the thrust reverser pursuant to the
disclosed embodiments is equipped with means for automatic closure
of the external door 301 and the internal door 302 so as to
maintain the doors in the closed position, which becomes a stable
position.
[0054] The external door 301 is composed of two surfaces S.sub.1A
and S.sub.1B, and the internal door 302 is also composed of two
surfaces S.sub.2A and S.sub.2B. The surfaces S.sub.1A and S.sub.2A
are delimited respectively by the free extremities 13, 14 of the
external door 301 and the internal door 302, and the pivot linkages
7, 8 of said doors with the extremities of the arms 401, 402. And
the surfaces S.sub.1B and S.sub.2B are delimited respectively by
the pivot linkages 7, 8 of said doors and the pivot linkages 5, 6
of said doors with the extremities of the nut 502.
[0055] The dimensions of these surfaces are such that the forces
generated by the pressure P1 of the external flow applied to the
surface S.sub.1A of the external door 301 and by the pressure P2 of
the secondary flow applied to the surface S.sub.2a of the internal
door 302 are greater than the pressure forces of the external flow
on the surface S.sub.1B and of the secondary flow S.sub.2B [sic],
with the resultant of the forces exerted on the doors then being in
a direction tending to maintain the doors in the stable closed
position. In this way, these means of automatic closure based
solely on the utilization of the pressures provide a guarantee that
no untimely opening of the doors 301, 302 can be produced when the
aircraft is in flight.
[0056] In addition, these means provide for avoiding the provision
of a locking mechanism for the reverser that necessitates
supplementary elements and supplementary manufacturing steps.
[0057] FIG. 5 shows an example of embodiment of a nacelle 100 for a
double-flow engine intended to be installed on an aircraft equipped
with reversers. In FIG. 5, the nacelle has four groups 601, 602,
603, 604 of three reversers each, arranged around an external
circumference 105 of the nacelle.
[0058] In another example of embodiment of a nacelle 100 for
aircraft, the thrust reversers are distributed at a regular
interval around the circumference. Depending on the spacing between
two adjacent doors, the number of thrust inverters per nacelle can
be varied. In particular, if the number of thrust reversers is
increased, the surface area of each door can be reduced, and the
risks of deformation of said doors can be limited.
[0059] Of course the nacelle can be equipped with different types
of thrust reversers. For example it is equipped with a thrust
reverser 300 according to the disclosed embodiments and a thrust
reverser pursuant to the prior art.
[0060] In the same way, it is possible to equip an aircraft with
one nacelle of the disclosed embodiments and one nacelle equipped
with thrust reversers of the prior art.
* * * * *