FR2545930A1 - WARNING SYSTEM FOR A TACTICAL AIRCRAFT - Google Patents

Abstract

THE INVENTION RELATES TO AIRCRAFT PILOT ASSISTANCE SYSTEMS. THE SYSTEM OF THE INVENTION WARNS THE PILOT OF A TACTICAL AIRCRAFT ENGAGING IN A PICK-UP WHEN HE HAS REACHED THE POINT AT WHICH HE MUST BEGIN RIGHTENING IMMEDIATELY SO AS NOT TO DESCEND BELOW A DESIRED MINIMUM ALTITUDE. FOR THIS PURPOSE, THE SYSTEM INCLUDES IN PARTICULAR A COMPARATOR 28 WHICH RECEIVES A RADIO-ALTIMETER SIGNAL, A TANGAGE ANGLE SIGNAL AND A DESCENT SPEED SIGNAL, AND WHICH PRODUCES A WARNING TRIP SIGNAL FOR DETERMINED CONDITIONS OF THE ENTRY SIGNALS. THE COMPARATOR EXIT SIGNAL ATTACKS A VOICE WARNING GENERATOR 30 THROUGH A LOGIC GATE 26 WHICH ENSURES THAT VARIOUS OTHER CONDITIONS ARE FULFILLED, TO AVOID THE GENERATION OF INTEMPESTIVE WARNINGS. APPLICATION TO TACTICAL AIRCRAFT.

Description

The present invention generally relates to

  the ground proximity warning systems and more specifically to a system that warns the pilot of an aircraft engaged in a tactical maneuver, such as a dive, to indicate that he must immediately begin to recover , to prevent the aircraft from descending below a

  desired minimum altitude that is selected by the

  setting of the radio altimeter marker, or

  minimum descent study (MDA) The system also gives

  warnings concerning unsafe flight conditions during common road segments or

  non-tactical flights, such as take-off, landing

age and the flight of cruise.

  Pro warning systems are known

  However, such systems are generally designed for aircraft from the ground that give warnings about various dangerous flight profiles.

  transport, and they are designed to give warning

  mainly in the take-off phases

  and landing of a flight, in order to prevent inadvertent

  piloted flight causes the aircraft to hit the ground Such systems are not designed to give warnings during tactical maneuvers such as

  dives, in which the pilot deliberately directs

  the aircraft to the ground at high speed and with a

  steep slope, and they would therefore provide warnings

  unsuitable or erroneous conditions under such conditions.

  The object of the invention is therefore to provide a system

  warning system that removes many of the

  prior warning systems of the prior art.

  Another object of the invention is to provide a warning of a dangerous flight condition during maneuvers.

  tactics, as well as during joint road segments

  such as take-off, landing and cross-country theft.

  IESO. Another object of the invention is to give a warning to the pilot of an aircraft engaged in a dive, to indicate to him that he must immediately begin to straighten the aircraft to prevent it from descending.

  from below a desired minimum altitude.

  Tactical aircraft present problems

  my specialties in the design of warning systems.

  proximity to the ground which warns the pilot of the aircraft of a dangerous flight condition. One of these

  problems arise because of the dual mode of

  Such an aircraft is typically

  aircraft operates in a tactical mode, or a mode of

  uses weapons, which includes maneuvers such as dives and various maneuvers at low altitude,

  as well as a non-tactical mode of operation, or corres-

  laying on common road segments, which includes maneuvers such as take-off, landing and

  cruising flight Because the maneuvers we encounter

  be in the tactical mode of operation of an aircraft are significantly different from those encountered

  characteristically in the non-tactical mode, a system

  designed me for a non-tactical aircraft or transport does

  will not provide appropriate warnings for some

  tactical maneuvers, while providing warnings

  mistakes during other maneuvers.

  Similarly, a specially designed system

  to give warnings during maneuvers

  tactics will not give appropriate warnings

  the less severe non-tactical maneuvers of a robbery. Therefore, a preferred embodiment

  of the invention provides a system which provides warnings

  dangerous flight conditions in

  tactical flight as well as in non-tactical phases.

  The system according to the invention controls the angle of tangency.

  and the speed at which the aircraft descends into the tactical mode of operation, and calculates the altitude at which an upright is to be triggered to prevent the aircraft from descending below a desired minimum altitude, selected by setting

  of the radio altimeter marker or the altitude of

  When the minimum altitude of

  is reached, the warning system transmits a

  specific auditory warning which is distinct from

  non-tactical operations, such as "INTERRUPT",

  to indicate that an adjustment must be triggered

  mediately Tactical warnings are not validated

  during the tactical flight phases, and some warnings

  non-tactical actions are invalidated during the

his tactics.

  The invention will be better understood when reading

  of the following detailed description of a mode of

  embodiment, and with reference to the accompanying drawings in which:

  Figure 1 is a schematic block diagram

  logic of the warning system in accordance with the

  tion; Figure 2 shows an aircraft in a dive and shows the dynamic elements of the recovery after the dive;

  Figure 3 is a graph showing

  altitude of an aircraft during a recovery at 4 G after a dive, as a function of the descent speed and the pitch angle; FIG. 4 is a graph showing the altitude loss of an aircraft during a 4 G rectification after a dive, as a function of the airspeed and the pitch angle; and

  Figure 5 is a block diagram of a system

  warning of proximity to the ground in accordance with the

  can be used for tactical maneuvers as for

non-tactical maneuvers.

  We will now consider the drawings, and in

  particular, Figure 1, which represents a mode of realization

  the tactical warning portion of the ground proximity warning system according to the invention,

  which is generally designated by the reference 10.

  For purposes of illustration, the system 10 conforms to the

  The invention is shown in FIG. 1 in the form of a logic block diagram comprising a series of gates;

  comparators and similar elements, but it is necessary

  that the actual realization of logical functions can

  other than that shown in Figure 1, and di-

  digital and analog implementations are possible.

  The signals used by the system described include the radio altitude, the speed of

  barometric altitude, airspeed and tan angle

  pledge of the aircraft, as well as signals indicating

  if the weapons are armed, and various signals of validity.

  Depending on the type of aircraft in which the warning system

  is installed, the signals shown in the figure

  re 1 can be obtained from individual instruments

  duels, such as a barometric altimeter 12, a circuit of

  determination of the speed of variation of the altitude

  14, a radio altimeter 16, a tan gyroscope

  pledge 18, a speed-air signal source 20, such

  which includes an air data dilator or an indicator of

  air-speed transmitter, and various circuit elements

  crunches that indicate whether the weapons are armed and whether the

  According to one variant, in some cases

  Some newer aircraft, these signals can be obtained

  from a digital data bus.

  The tactical warning part of the system

  according to the invention is designed so as to function

  only during a tactical flight phase, such as a

  bombing or ground attack, during which

  a steep dive condition is encountered

  Therefore, the system is validated only when conditions

  In the embodiment under consideration, these conditions are as follows: the wheels do not support the weight of the aircraft, the airspeed is greater than a predetermined airspeed, like for example 300 knots,

and the weapons are not armed.

  The validation function is provided by a

  AND gate 22 which receives signals indicating that the

  my are armed and that the wheels do not support the

  weight of the aircraft, as well as a signal from a

  paratrix 24 which is connected to the signal source of

  The comparator 24 compares the signal

  from the air-speed signal source 20 with a signal

  reference standard representative of a predefined air velocity

  completed, for example 300 knots, and it indicates the moment

  the airspeed of the aircraft exceeds a speed

  predetermined air, for example 300 knots AND gate 22

  additionally receives signals indicating that radio altimetry

  is not off and that the barometric altimeter

  that is not off, in order to put the system

  off in case an instrument is defective.

  When all the above conditions are fulfilled, the gate 22 validates another AND gate 26, to place the gate 26 under the control of a comparator 28 which receives a signal representative of the pitch angle

  of the aircraft, from the pitch gyroscope 8, a

  general representative of the barometric descent speed of the aircraft from the speed variation circuit

  14, as well as a signal representative of the altitude of

  The minimum setting that is set by the ADX setting On the basis of these input signals, comparator 28 determines

  the minimum altitude of recovery, or an altitude of

  HW, to which the adjustment must be

  latched to prevent the aircraft from descending below the minimum descent altitude The comparator receives

  also a signal representative of the altitude of the air-

  nave above the ground from the radio altimeter 16, and

  it applies a signal to the door 26 in the case where the

  received from radio altimeter 16 is representative

  altitude below the minimum altitude of

  At the reception of such a signal, the door 26 de-

  triggers the operation of the warning generator, which is preferably a digital voice warning generator, so that the generator 30 produces a voice warning The voice warning must be a specific warning, such as "STOP" to indicate exactly to the pilot the action he has to

  perform to avoid a dangerous flight condition.

  The voice warning is applied directly or indirectly

  to a transducer 32, such as a loudspeaker or

  listener, to be transmitted to the pilot.

  There are other factors besides

  and the pitch angle of the aircraft, which determine the altitude at which the nose-down turnaround warning is to be generated. These factors relate to the performance of the aircraft and include the reaction time of the aircraft. aircraft and pilot, and the number of G that the aircraft can withstand during a turnaround In a typical rectification maneuver, the aircraft's trajectory is approximately an arc at the bottom of

  the righting maneuver The radius of the circle is deter-

  the number of G that the aircraft can produce during the righting maneuver, and the radius of curvature of the arc is inversely proportional to the number of G that is produced. Looking at Figure 2, we see an aircraft

  50 which has just passed through the minimum altitude of

  or warning altitude, HW, and which starts

  its recovery Assuming that the recovery is

  satisfactorily, the aircraft will arrive in horizontal flight at the minimum descent altitude, ADM, and begin to climb in the manner indicated by the dashed line. The righting course shall be a first approximation of a circle whose radius , R, will be determined by the number of G's that the aircraft can produce

during his recovery.

  For an object moving on a circle, the

  normal celerity, ie radial acceleration, directed inwards, is directly proportional

  squared the speed of the object and conversely

  tional to the radius of the circular path that the object describes Mathematically, this relation is written v 2 an = (1) R denoting by year the normal acceleration, directed towards the interior, which the object undergoes during the turn , by V the velocity of the object and by R the radius of curvature of the

trajectory of the object.

  If the descent angle of the aircraft 50, represented

  given by the dive angle or given approximately by the pitch angle, is equal to 0, it is easy to establish a relationship between the descent speed of the aircraft and its speed, using simple trigonometric relations, or more precisely H b V = sin o (2) denoting by Hb the speed of descent of the aircraft, or more precisely the barometric descent speed. In the embodiment of the invention which is represented,

  the speed of descent

  than; but we can however use in certain modes of

  the speed of approach to the ground or the vi-

  rate of variation of radio altitude.

  If the nose angle of the aircraft is G,

  geometric principles indicate that the angle between a

  yon which is perpendicular to the trajectory of the aircraft and the vertical is also equal to Q (Figure 2) Therefore, the distance between the center 52 of the circle and the warning height, Hw, is equal to R cos 9, and

  the distance between the warning height Hw and the altitude

  minimal descent study, ADM, is equal to R (1-cos 9).

  This last relation makes it possible to calculate the value of

  the altitude loss, at H, between the warning height

  Hw, and the minimum descent altitude, ADM, based on

  angle of the aircraft and the radius, R, of

  the circular trajectory described by the aircraft.

  Because the radius of the trajectory of re-

  is based on the speed of the aircraft and the number of G it can produce during a recovery, the altitude loss between the warning altitude and the ADM can be calculated as a function of the speed of the aircraft.

  the aircraft and the number of G it produces during the

  In addition, because the descent speed of the aircraft is a function of the aircraft speed and the dive angle, it is possible to calculate the altitude loss CH, during the recovery, according to the speed of descent and the number of G that the aircraft produces in the recovery.

  This is accomplished in the following manner.

  both of the relation (2), raising it squarely and

  killing appropriate trigonometric substitutions, one obtains

holds the following relationship

2 2 H

  2 Hb Hb b H V 2 2 (1 + cos G) (1-cos O) (3 o sin Q (1-cos O)

  By rearranging relation (1) and

  in relation (3), we obtain 2 ORV 2 _ Hb R = a Ea (1 + cos 0) (1-cos) (4) nn By multiplying the relation (4) by (1-cos 0), we obtain the altitude loss during the recovery, at H, in the following manner: Hb H 1 n (i + cos 0)

  The relationship mentioned last defines the

  altitude of the aircraft between the moment at which the

  at the end of the dive is triggered and the moment

  which aircraft is flying horizontally; it does not hold

  not take into account the reaction time of the pilot and the aircraft, nor does it take into account the minimum altitude desired.

  these factors in the equation defining the height of warnings

  tation, Hw, to ensure that the warning is

  given sufficiently t 8 t to allow the pilot to

  Safely The minimum descent altitude can easily be taken into account by adding the ADM setting to the altitude loss. The reaction time can be taken into account by adding in the equation a term equal to the time of the descent. pilot and aircraft reaction, for example

  2 seconds, multiplied by the speed of descent

  The warning equation Hw is therefore given by the following equation:

  praise: * 2 Hb Hw ban (+ cos 0) + 2 Hb + ADM (6)

  in which the factor which multiplies the term Hb represents

  feel the 2-second reaction time of the pilot and the aircraft.

  We can use the equation above to de-

  to finish an altitude to warn t, Hp, fear various types

  of aircraft, having various characteristics of performar -

  However, a recovery at 4 G is that which is

  typically read during tactical maneuvers, because it does not subject the pilot to undue stresses. Thus, using 4 G for normal acceleration, ar, and solving the equation above for a recovery at 4 G and a reaction time of 2 seconds,

  using digital techniques, we obtain the

  next result * 2 Hw = (H * (0,005176 + 0,0000236 * (Qp 11) +

0.0000321 * (Q -40) + 2H + ADM

p b In this relationship:

  Hw is the warning height, in meters, corre-

  laying at a radio altitude,

  Hb is the speed of variation of the barometric altitude

  in meters per second, 9 p is the pitch angle in degrees,

  ADM is the minimum desired altitude, in meters.

  In the equation above, the terms (O p-11)

  and (Op-40) can not become negative.

  if the pitch angle is respectively less than 11 degrees or less than 40 degrees, the terms (p 11)

  and (Op 40) are set to zero In addition, we use the

  the pitch of the aircraft instead of the dive angle to represent the angle of descent, because

  easily get the pitch angle, from a gyros-

  cope or similar, while this is not the case for the dive angle; however, we can use

  the actual dive angle in the calculation The dive angle differs

  the angle of pitch by the angle of attack of the wings

  which is typically only a few degrees.

  Thus, the fact of using in the calculation the pitch angle

  instead of the dive angle gives a satisfactory approximation

  warning height In addition, we use

  read the numerical approximation of the trigonometric equation

  that setting the warning height because it allows the warning system according to the invention to perform simple multiplications, instead of trigonometric calculations much more complex, which provides

a shorter response time.

  Figure 3 shows the envelope of

  the recovery mode at the end of the system

  warning device according to the invention, for an adjustment

  at 4 G Figure 3 shows the loss of altitude, b H, as a function of the speed of descent, for various pitch angles As can be seen in Figure 3, the loss

  altitude, to H, and therefore the height of warnings

  hw, increase when the speed of

  the ground increases and when the pitch angle increases

  However, since the cosine function varies slowly

  For low angles, the curve of Figure 3 is relatively independent of the pitch angle for low pitch angles, ie

  less than 400. It is therefore possible to use the same

  be to set the warning boundary for

  pitch gages of about 400 and below.

  In addition, as previously indicated, the descent speed and the airspeed are related by the

  sine of the dive angle Therefore, we can also

  define the warning envelope based on the airspeed, instead of the speed of descent, as

  shown in Figure 4, which shows the loss of

  study at H, as a function of the air velocity and the angle of

  pitching Thus, in another embodiment of the irn-

tion, a comparator 28 signal can be applied to

  velocity-air, instead of the descent rate, and the curves of Figure 4 can be used,

  instead of those in Figure 3, to determine

  altitude and the warning height.

  Looking at Figure 5, we see a

  the end-of-dive recovery warning system which is used in conjunction with

  that produce warnings of flight condition dan-

  in a variety of non-tactical flight conditions.

  In the block diagram of FIG. 5, the same numbers are used to denote the components identical to

  those shown in Figure 1, and use is made of

  assigned the premium symbol to designate components of the non-tactical part of the warning system that are identical to components of the tactical part of the system that are designated by the same number without the premium symbol. Thus, the non-tactical part of the system

  10 'is analogous to the tactical part of the -

  warning system 10, and the warning generator

  non-tactical 30 'is analogous to the warning generator.

Tactical operation 30.

  The system 10 'shown in FIG.

  also reads various signals representative of various

  the aircraft's flight ranges, including airspeed, radio altitude, speed of

  the barometric altitude, the speed of variation of

  radioelectric study, a signal representative of the

  of minimal descent, ADM, a signal representative of

  weapons, a signal representative of the posi-

  landing gear, as well as various validity signals (not shown) as in the case of the

  10, the system 10 'receives the signals either from di-

  individual instruments and various elements of cir-

  cooked discrete, either from a digital data bus.

  The system 10 'analyzes the received signals and performs a warning function in the case where a dangerous flight condition exists. Among the characteristic functions fulfilled by the system 10' are the functions which are described in the patent applications US 494,589,

  494,590, 494,591, 494,593 and 494,594.

  The system 10 'may contain one or more of the warning functions described in the aforementioned applications, or other warning functions, and it operates during the non-tactical phases of the flight of the aircraft. The system 10' controls the operation of a 30 'non-tactical warning generator and it does

  so that the generator 30 'produces various warnings

  voice events that are applied to the transducer 32, or

  to another suitable transducer, to inform the pilot

  Dangerous Flight Condition During Non-Tactical Flight Phases Such warnings include:

  typically: "DO NOT DESCEND", which indicates

  only to a pilot-that he goes down after takeoff, "TOO

  "Indicating to a pilot that he is flying below the

  Minimum descent titrate, "GROUND", which warns a pilot of excessive ground clearance during low-level flight, "DESCENT SPEED", which indicates to a pilot that he is descending too rapidly while approaching a landing, and "TOO LOW, TRAIN RETURN" which warns a pilot in case he tries to land with the train

landing returned.

  Although all these warnings are useful during non-tactical flight phases, some of these warnings may be erroneously triggered during tactical flight phases, thus producing

  In particular, warnings

  the word "SOL" and the warning "SPEED OF DESCENT" are

  likely to be produced during tactical maneuvers

  the fact that the speed of variation of the altitude ra-

  dioelbtric as the speed of variation of altitude

  are high during tactical maneuvers.

  Therefore, the non-tactical modes that are most

  likely to be triggered by mistake must be

  validated during tactical maneuvers The system 10 'thus includes an entry "ARMS NOT ARMED" which prevents the

  generation of any warnings, such as

  the warnings "SOL" and "DO NOT DESCEND", and other warnings that would lead to the generation

  inadvertent warnings during tactical maneuvers

  Such a signal can conveniently be obtained from

  firing of a weapon arming contact 40 used to arm the aircraft weapons Such a contact can be used to apply to the system 10 'a signal "WEAPONS NO

  ARMED ", to invalidate all warnings that

  could be inadvertently triggered during a

  tactical flight, as well as to validate the warning system.

  tactical 10 during tactical flight phases.

  It goes without saying that many modifications can be made to the device described and shown,

  without departing from the scope of the invention.

'

Claims (7)

  1 System intended to indicate to the pilot of an aircraft engaged in a dive the altitude at which he must begin the recovery to avoid descending below a predetermined altitude, characterized in that it comprises: means (28 ) who react to the   speed of descent and the angle of descent of the aircraft   nave so as to determine the minimum altitude at which   the recovery must be started to avoid   below the predetermined altitude; and some   yens (26, 30, 32) which operate in dependence on the altitude of the aircraft and the means of determination so as to give a warning to the pilot when must start the recovery.   System according to claim 1, in the   which means (28) that respond to the speed of des-   and the angle of descent include means responsive to the barometric descent rate of the aircraft.   3 System according to claim 1, characterized   in that the means (28), which respond to the descent rate and the descent angle, comprise means   which react to the pitch angle of the aircraft.   4 System according to claim 1, characterized   in that the means (28) responsive to the altitude of   the aircraft comprise means that react to the from the aircraft above the ground.   A ground proximity warning system operable to produce warnings indicative of dangerous flight conditions of an aircraft in tactical and non-tactical phases of aircraft operation, characterized in that it comprises: first-means ( 10 ',') which respond to flight conditions of the aircraft during non-tactical flight phases by producing a warning indicative of a dangerous flight condition;   second means (10, 30) responsive to conditions   aircraft during flight phases of tactical flight.   ticks, so as to produce a warning indicating a dangerous flight condition; and means (10 ', 22) which invalidate the generation of a warning by the   means responding to non-tactical flight phases,   the aircraft is in a tactical flight phase.   Ground proximity warning system according to claim 5, characterized in that the means   of invalidation comprise means (10 ') which react   feel at a weapon arming signal.   7 Ground proximity warning system   according to claim 5, characterized in that the first   first warning generation means (10 ') react   at the altitude of the aircraft above the ground in   warning if the altitude above the ground decreases at an excessive speed.   8 Ground proximity warning system   according to claim 7, characterized in that the   Disabling means include means (10 ') for preventing the generation of the warning that the altitude above the ground is decreasing excessively fast. 9 Ground proximity warning system   according to claim 5, characterized in that the first   first warning generation means (10 ') react   the speed of descent of the aircraft by producing a   warning if the aircraft descends at an excessive speed.   Ground proximity warning system according to claim 9, characterized in that the means   of invalidation include means (10 ') for   to fish for the generation of the warning that the   in excessively fast, when weapons are armed -