This application claims priority under 35 U.S.C. §§119 and/or 365 to 0007927 filed in France on Jun. 21, 2000; the entire content of which is hereby incorporated by reference.

BACKGROUND

1. Technical field

The invention relates to a device designed to support a flying instrument such as a prototype or a missile model in a wind tunnel, so as to study the behavior of this instrument under different attitudes, with its motor on.

The invention applies to wind tunnel tests carried out on any type of motorized flying instrument and particularly a prototype or a scale one model, fitted with a motor, of a missile of which it is desired to study the behavior in real time in a supersonic tunnel, hands off, by reconstructing the changes in dynamics representative of the flight attitudes of the instrument.

2. Prior art

As shown in documents FR-A-2 159 548 and FR-A2 641 378, there is a known technique of wind tunnel testing the aerodynamic behavior of a model of a flying instrument such as an aeroplane by mounting this model on a boom connected to the fixed structure of the wind tunnel by a set of mechanisms allowing the attitude of the model being tested to be varied in real time. When this technique is used, the rear end of the model is connected to the front end of the boom and the latter extends backwards approximately in the extension of the model.

Support devices of this type make it possible to study, hands off, the aerodynamic behavior of the flying instrument surfaces which are in contact with the ambient air, when the attitude of the instrument changes in time.

On the other hand, such support devices cannot be used to study the behavior of a flying instrument whose motor or motors are switched on. Indeed, the presence of a boom approximately in the extension of the model, to its rear, does not allow a motor located in the longitudinal axis of the instrument to be switched on and greatly disturbs the airflow leaving a motor offset relative to this axis.

At the present time, when flying instruments are wind tunnel tested with their motors on, support devices of a different design are used. These support devices include several articulated supports connecting the instrument to the fixed structure of the wind tunnel. The articulated supports are presented usually in the form of arms or pylons at least one of which comprises length adjustment means. Most often, three or four articulated supports are used.

In such a support device, the articulated supports are offset towards the rear relative to the front part of the instrument, so as not to disturb the airflow in this zone. Moreover, to allow the behavior of the instrument to be studied while the motor is on, the articulated supports are also located clearly outside the airflow zones located upstream and downstream of the motor.

When such a support device is used to study the behavior of an instrument the motor of which is on, operators adjust the required configuration and flight attitude (sideslip value, incidence angle, etc.) by acting on the length adjustment means, before proceeding to a test. When another configuration and another flight attitude are to be tested, it is necessary to stop the instrument motor and to intervene again manually on the length adjustment means before proceeding to a new test.

This conventional technology is particularly long and tedious to implement. Moreover, it does not allow the dynamic behavior, in real time, of an instrument with its motor on to be studied. In particular, existing support devices are ineffectual for studying the behavior of an instrument with its motor on when it describes a pre-set trajectory or trajectory fraction.

BRIEF SUMMARY

The exact object of the invention is a support device designed to allow the study of the behavior of a motorized flying instrument in a wind tunnel when the instrument motor is on, by enabling a modification in real time of the attitude of the instrument for the articular purpose of simulating a trajectory or rajectory fraction followed by the latter.

In accordance with the invention, this result is obtained by means of a device able to support a motorized flying instrument in a wind tunnel, so as to study the behavior of said instrument, with its motor on, under different attitudes, said device including several articulated supports able to connect the instrument to a fixed structure of the wind tunnel, at places offset relative to airflow zones located around a front part of the instrument and upstream and downstream of the motor, at least one of said supports comprising length adjustment means, the device being characterised in that the length adjustment means are connected to remote control means able to modify in real time the instrument attitude.

Since the length adjustment means are remote controlled, the instrument attitude may be modified in real time, hands off. It thus becomes possible, particularly, to study the behavior of a flying instrument with its motor on, by simulating a trajectory or trajectory fraction followed by this instrument.

In a preferred embodiment of the invention, the supports include a front support, of invariable length, incorporating articulation means to at least two degrees of freedom of rotation around two axes oriented along two directions orthogonal to each other and to a longitudinal axis of the instrument, and two rear supports each incorporating length adjustment means and pivot connections.

To advantage, the front support is oriented approximately radially relative to the longitudinal axis of the instrument and arranged in a vertical plane passing through this axis. The rear supports are then oriented radially relative to the longitudinal axis of the instrument and arranged symmetrically relative to the aforementioned vertical plane, when the two rear supports are in an initial state corresponding in particular to a zero sideslip value and to a zero incidence angle.

In this same initial state, the rear supports preferably form with the vertical plane an angle such that the mounting of the instrument on the device is isostatic. This angle is for example approximately equal to 45°.

In the preferred embodiment of the invention, the rear supports are offset towards the rear by about one meter relative to the front support, along the longitudinal axis of the instrument.

Furthermore, the length adjustment means are constituted preferably by hydraulic jacks servo-controlled lengthwise.

To reduce as far as possible the airflow disturbance induced by the front and rear supports, each of these supports is generally placed inside a streamlined casing. This casing also provides thermal protection for the supports and contributes to their mechanical strength.

To provide control in real time of the configuration and flight attitudes of the instrument, angular measurement means such as resolvers are to advantage associated with the articulation means.

To take account of the significant increases in temperature which occur in the wind tunnel, in the vicinity of the instrument (about 350° C.), cooling means are additionally provided to cool the pivot connections and the angular measurement means located in the immediate vicinity of the instrument.

BRIEF DESCRIPTION OF THE DRAWINGS

A description will now be given, as a non-restrictive example, of a preferred embodiment of the invention, with reference to the appended drawings, in which:

FIG. 1

is a side view showing diagrammatically a motorized flying instrument mounted in a wind tunnel by a mounting device according to the invention;

FIG. 2

is a front view showing the instrument diagrammatically in its initial state (solid line), with a modified incidence angle (dot and dash line) and with a modified sideslip value (dotted line);

FIG. 3

is a perspective view of the encased front support of the mounting device according to the invention;

FIG. 4

is a front view, on a larger scale and in partial cross-section, of the front support; and

FIG. 5

is a front view, in partial cross-section, of the rear supports of the mounting device according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

In

FIGS. 1 and 2

, a diagram is given showing a flying instrument

10

such as a prototype or a missile model, placed in a wind tunnel

11

. The flying instrument

10

is fitted with one or more motors intended to be switched on when wind tunnel tests are carried out.

In accordance with the invention, the flying instrument

10

is connected to the fixed structure of the wind tunnel by a support device

12

designed to simulate, in real time and hands off, changes in dynamics of the instrument

10

, representative of the its flight attitudes when it passes through a given trajectory or trajectory fraction.

In the preferred embodiment of the invention shown in the figures, the support device

12

includes a front support

14

and two rear supports

16

.

In this case, the front support

14

, of invariable length, connects the instrument

10

to the floor

15

of the fixed structure of the wind tunnel

11

. It is located in a vertical plane passing through the longitudinal axis A of the instrument

10

and oriented approximately radially downwards relative to this axis.

As is shown more exactly in

FIG. 4

, the front support

14

includes a vertical pylon

18

constituted by a rigid metal tube the lower end of which is fixed to the floor

15

of the fixed structure of the wind tunnel

11

and the upper end of which supports the flying instrument

10

, through articulation means

20

. These articulation means

20

define at least two degrees of freedom of rotation around two axes B and C oriented along two directions orthogonal to each other and to the longitudinal axis A of the instrument

10

. A first B of these two axes is merged with the vertical axis of the pylon

18

. The second axis C, oriented along a transverse direction relative to the instrument

10

, passes preferably approximately through its lower generator.

More exactly, the articulation means

20

include a vertical mast

22

a lower part of which forming a pivot is received into a bore

23

formed in the pylon

18

, along the axis B. This arrangement allows the mast

22

to swivel freely around the vertical axis B of the pylon

18

, by means of bearings

19

. Thrust ball bearings

21

, locked by a nut

17

, are also provided between the foot of the pylon

18

and the mast

22

, to give a system without play. The pylon

18

is made in two parts, to make it possible to mount the bearings

19

, the stops

21

and a resolver

56

which will be described subsequently.

In its upper part, located above the pylon

18

, the mast

22

forms a clevis in which is received a pivot

24

, by means of bearings

25

. This pivot

24

is integral with a complementary clevis

26

fixed under the flying instrument

10

on which tests are to be conducted. The axis of the pivot

24

corresponds to the transverse axis C defined previously. This arrangement allows the instrument

10

to swivel freely around the axis C, relative to the mast

22

.

The clevis

26

, by which the front support

14

is fixed to the flying instrument

10

, is located in the front half of this instrument. However, this location is offset towards the rear relative to the front part of the instrument, so as not to disturb the airflow in this particularly sensitive region. By way of an example which is not in any way restrictive on the invention, the clevis

26

is located at least one third of the way up the length of the instrument

10

, starting from its front point.

It may be noted that as an alternative, instead of being placed underneath the flying instrument

10

, the front support

14

could be located above it and connected by its upper end to the ceiling (not shown) of the fixed structure of the wind tunnel

11

.

As shown in

FIG. 1

, the two rear supports

16

are oriented radially relative to the longitudinal axis A of the instrument

10

and located in the same vertical plane P

1

perpendicular to this axis, preferably about one meter behind the front support

10

. More exactly, when the support device

12

is in its initial state, in which incidence and slip are zero, as shown in a solid line in

FIG. 2

, the two rear supports

16

(shown here diagrammatically in segments) are arranged symmetrically on either side of the vertical plane P

2

passing through the front support

14

and through the longitudinal axis A of the instrument

10

.

As shown in

FIG. 5

, each of the rear supports

16

includes length adjustment means constituted, in the embodiment shown, by hydraulic jacks

28

servo-controlled lengthwise. More exactly, each of the rear supports

16

essentially includes a hydraulic jack

28

and two pivot connections

30

and

32

by which the opposite ends of the jack

28

are articulated on a first clevis

34

fixed to the floor

15

of the fixed structure of the wind tunnel

11

and a second clevis

36

fixed under the flying instrument

10

respectively.

The lower end of each of the hydraulic jacks

28

is articulated on the corresponding clevis

34

by a pivot

38

oriented parallel to the longitudinal axis A of the instrument

10

. Comparably, the upper end of each of the hydraulic jacks

28

is articulated on the clevis

36

by a pivot

40

the axis of which is oriented parallel to the longitudinal axis A of the instrument

10

.

When the support device

12

is in its previously defined initial state, the two hydraulic jacks

28

(and, consequently, the two rear supports

16

) are the same length. Moreover, they are both inclined by 45° relative to the vertical plane P

2

passing through the longitudinal axis A of the instrument, so as to form between them an angle of 90°.

The arrangement which has just been described is such that the mounting of the instrument

10

on the fixed structure of the wind tunnel, provided by the support device

12

, is isostatic.

The hydraulic jacks

28

constituting the length adjustment means are connected to remote control means

42

(FIG.

1

). These remote control means

42

act on the hydraulic jacks

28

, in real time and hands off, so as to modify their length in a controlled way. It is thus possible to vary in real time and continuously characteristics specific to the attitude of the instrument in flight, such as sideslip and/or incidence, while the instrument motor is operating. This arrangement makes it possible to study the behavior of the instrument

10

, with its motor on, under different attitudes and particularly during a complete trajectory or trajectory fraction able to be followed subsequently by the instrument.

So it can be seen in a dot and dash line in

FIG. 2

that a same increase in length of each of the two jacks

28

is translated by an increase dz in the height of the instrument

10

in the vertical plane P

1

. Because the height of the instrument in the vertical plane passing through the front support

14

remains unchanged, we move from zero incidence to controlled negative incidence.

Comparably, it can be seen in a dotted line in

FIG. 2

that the combination of an increase in length of one of the jacks

28

and a decrease in length of the other jack

28

, in a controlled relationship by remote control means

42

, is translated by a lateral offset dy of the instrument in the plane P

12

. We thus move from zero slip to controlled slip, to the right or to the left.

As shown in

FIGS. 3 and 4

, the front support

14

, the length of which is invariable, is housed within a streamlined casing

44

. This casing has in cross-section approximately the shape of a diamond with broken corners, the main diagonal of which is oriented parallel to the axis A of the instrument. It may be noted that the cross-section of the streamlined casing

44

steadily increases the further it gets from the instrument

10

.

Comparably (FIG.

5

), each of the rear supports

16

is placed within a streamlined casing

46

which also has in cross-section approximately the shape of a diamond the main diagonal of which is oriented parallel to the axis A of the instrument

10

. The casing

46

is fixed to the upper end of the corresponding jack

28

articulated on the clevis

36

by the pivot

40

. The lower end of each of the casings

46

penetrates freely in a sleeve

48

which surrounds the lower part of the jack

28

. The lower and upper ends of each of the sleeves

48

are fixed to the clevis

34

and to the wind tunnel

11

respectively. The arrangement is such that the upper part of the sleeve

48

is connected to the wind tunnel

11

at a location such that the lower end of the casing

46

is always within the sleeve

48

when the jack

28

is extended to its maximum. The positioning of the lower part of the casing

46

around the jack

28

is provided by a centring bush

50

fixed to the casing

46

and allowing the jack rod

28

to slide (the casing

46

follows the movements of the jack).

Each of the sleeves

48

houses control components

54

(

FIG. 1

) of the corresponding jack

28

. These control components

54

include particularly a servovalve and a clack valve system connected to the remote control means

42

. The positioning of the control components

54

outside the wall

50

of the wind tunnel allows these components to be placed outside the hot areas located in the vicinity of the instrument being tested. These hot areas can in fact reach very high temperatures, generally in the region of 350° C.

So as to provide a very accurate control of the pivoting angles around the axes B and C defined by the articulation means

20

of the front support

14

, a first angular measurement means

56

(

FIG. 4

) is interposed between the mast

22

and the pylon

18

to measure the rotations around the axis B and a second angular measurement means

58

is interposed between the mast

22

and the clevis

26

, to measure the rotations around the axis C. These two angular measurement means

56

and

58

are constituted to advantage by resolvers able to supply an angular measurement with an accuracy of about one hundredth of a degree.

The first resolver

56

is placed inside the pylon

18

. It is therefore protected from the high temperature prevailing inside the wind tunnel. On the other hand, the second resolver

58

is placed in the immediate vicinity of the wall of the instrument being tested and it is only separated from the very hot ambient air by the sheet of the casing

44

.

Consequently, cooling means are to advantage provided for the resolver

58

. These cooling means include a tube

60

(shown diagrammatically by a line in

FIG. 4

) housed inside the casing

44

and allowing cool air to be conveyed to the resolver

58

from a cooling system (not shown) located outside the wind tunnel

11

.

Comparably, cooling means are provided to cool each of the pivots

40

by which the jacks

28

are articulated on the clevis

36

fixed to the instrument

10

. Airflow rates from the cooling means are controlled by means of calibrated necks located at the end of the tubes, at the level of the parts to be cooled (for example 100 g/s). These cooling means include, in this case too, tubes

62

(shown diagrammatically by lines in

FIG. 5

) passing within the corresponding casing

46

and within the sleeve

48

. At their end located outside the wind tunnel

11

, these tubes

62

are also connected to a cooling circuit (not shown) delivering cold air. It may be noted that the tubes

62

comprise at least one telescopic or flexible part allowing them to support variations in length of the hydraulic jacks

28

of the corresponding rear supports

16

.

Clearly, the invention is not restricted to the embodiment which has just been described as an example, but covers all its alternatives. Thus, it will be understood particularly that the front support and/or the rear supports could be placed not underneath but above the instrument being tested, without departing from the framework of the invention. Furthermore, the hydraulic jacks

28

can be replaced by electrical jacks, provided that their relatively long response time is compatible with the simulated trajectory, or by pneumatic jacks, provided that the volume taken up by the latter is not too restricting. Lastly, the articulation means

20

may incorporate a third degree of freedom of rotation orthogonal to the two degrees of freedom of rotation described.