FR2553507A1 - WARNING SYSTEM FOR A ROTATING TACTICAL AIRCRAFT - Google Patents

Abstract

THE INVENTION RELATES TO PILOT ASSISTANCE SYSTEMS FOR TURNING-BLADE AIRCRAFT. A WARNING SYSTEM FOR A ROTATING AIRCRAFT AIRCRAFT INCLUDES IN PARTICULAR ALTITUDE AND AIRSPEED COMPARATORS 16, 18, 28, 30 WHICH MONITOR THE AIRCRAFT'S ALTITUDE ABOVE THE GROUND BASED ON ITS SPEED- AIR AND APPLY A WARNING TRIP SIGNAL TO VOICE WARNING GENERATORS 38, 42 WHEN THE AIRCRAFT IS AT INSUFFICIENT ALTITUDE IN CONSIDERATION OF THE SPEED AT WHICH IT IS FLYING. THE WARNING CRITERIA ARE OPTIMIZED FOR A ROTATING CANOPY AIRCRAFT AND ARE CHANGED DEPENDING ON AIRSPEED AND LANDING GEAR POSITION. APPLICATION TO TACTICAL HELICOPTER EQUIPMENT.

Description

The present invention relates generally to systems

  ground proximity warning system, and more particularly to a ground proximity warning system for giving the pilot of a rotary wing aircraft a warning in case of insufficient clearance from the ground, or in case landing attempt with the landing gear retracted. Systems are known to give a warning to the pilot of an aircraft in case of insufficient clearance from the ground, or in case of attempted landing with the gear retracted. US Pat. No. 3,934,221, 3 934,222, 3,944,968 and 4,030,065 disclose

examples of such systems.

  Although these systems do provide

  ground clearance warnings, they are primarily designed for use with transport aircraft, and are not readily applicable to rotary wing aircraft whose flight characteristics and operational characteristics are significantly impaired. different from those of transport aircraft.

  The object of the invention is therefore to provide a system

  warning which removes many of the disadvantages of the warning systems of the prior art.

  The invention also aims to provide a warning to the pilot of a rotary wing aircraft in case

  insufficient clearance from the ground.

  Another object of the invention is to provide a warning system which warns the pilot of a rotary wing aircraft if he attempts to land with the landing gear retracted.

  Yet another object of the invention is to provide a warning system for alerting the pilot of a rotary wing aircraft of an insufficient clearance condition with respect to the ground, in which the criteria

I'553507

  According to a preferred embodiment of the invention, a system which controls the altitude above the ground and the airspeed of the aircraft is optimized according to the performance and operational characteristics of a rotary wing aircraft. the aircraft and that produces a vocal warning such as "TOO LOW, SOL" when the altitude of the aircraft from the ground is insufficient given the airspeed at which the aircraft flies. Criteria required to produce a warning are changed when the

  landing gear is retracted, and a separate separate warning such as "TOO LOW, TRAIN RENTER" is produced if the pilot attempts to land with the landing gear retracted.

  The invention will be better understood on reading the following detailed description of an embodiment.

  and with reference to the accompanying drawings, in which: FIG. 1 is a logical block diagram of the part of the system according to the invention which gives a warning in the case of insufficient clearance from the ground; Fig. 2 is a graph showing the relation between the airspeed of the aircraft and the altitude above the ground which is necessary to produce a warning when the landing gear is retracted; and FIG. 3 is a graph showing the relationship between the airspeed of the aircraft and the altitude of the aircraft above the ground that is required to produce a warning when the landing gear of the aircraft

is out.

  The drawings will now be considered, and in particular FIG. 1, which represents an embodiment of the ground clearance portion of the warning system according to the invention, generally designated by the reference numeral 10. For purposes of illustration, the system 10 according to the invention is shown in FIG. 1 in the form of a logic block diagram comprising a series of gates, comparators, flip-flops and the like; it should be noted, however, that the actual embodiment of the system may be other than that shown in FIG. 1, and various digital and analog implementations are possible. The signals used by the warning system which is described include altitude.

  and airspeed, as well as a signal representative of the position of the landing gear, various discrete signals indicating the operating mode of the aircraft, for example a tactical or non-tactical mode or anti-countermeasures. -Mines CMAM, and various signals of validity.

  Depending on the type of aircraft in which the warning system is installed, the signals shown in FIG. 1 can be obtained from individual instruments such as a radio altimeter 12, a speed-air signal source 14, as for example, a data calculator relating to air or a toy, and various discrete elements such as a contact indicating the position of the landing gear, a tactical mission contact and a contact of anti-countermeasures. According to one variant, in certain newer aircraft, these signals can be obtained from a bus

digital data.

  As indicated above, the warning system according to the invention provides two different warnings of insufficient clearance from the ground, according to two different warning criteria, according to

  the landing gear of the aircraft is retracted or extended.

  In the embodiment shown, the averaging criteria for the "retracted train" configuration are defined

  by a retracted train warning builder, 16, while the criteria for producing a warning in a "train-out" configuration are defined by an outgoing train comparator 18 The two comparators 16 and 18 receive signals representative of altitude of the aircraft

  above the ground from the radio altimeter 12, and a signal representative of the airspeed of the aircraft from the airspeed signal source 14, and they produce a warning trigger signal when the relationship between the altitude above the ground and the airspeed is such

  that there is insufficient clearance from the ground.

  To avoid inadvertent warnings, the system according to the invention is invalidated during take-off. The invalidation function is fulfilled by a departure base 20 which is positioned during take-off and restored during other flight phases. is positioned by an AND gate 22 under the following conditions: the landing gear is extended and the aircraft is below 30 m radio altitude and the aircraft speed is less than 40 knots or the aircraft is within 3 m, as indicated by signals applied to an OR gate. The flip-flop 20 is restored by an OR gate 26 once the aircraft's altitude above the ground exceeds 60 m or when the signal TACTICAL INVALIDATION indicating a tactical mission is applied to the gate 26 The various signals representative of various airspeeds and altitudes are provided by a speed-air comparator 28 and a comparator The airspeed comparator 28 receives signals from the airspeed signal source 14 and compares the speed signal with a reference signal representative of a predetermined speed, such as 40 knots, and it applies a signal to the gate 24 whenever the airspeed is greater than 40 knots. Similarly, the altitude comparator 30 compares the altitude signals from the radio altimeter 12 with various reference signals produced in a manner similar to the internal (or external) representative of various altitudes, and it provides various output signals that

  indicate whether the altitude is higher or lower than the reference altitude. For example,

  The altitude transmitter 30 applies to various gates in the logic circuits output signals which indicate whether the aircraft is below 3 m, above 3 m, below

  30 m and above 60 m radio altitude.

  The system is invalidated by the signal GENERAL INVALIDATION which invalidates a pair of gates 32 and -34 in the event that an instrument is defective In addition, the gates 32 and 34 are invalidated by the INVALIDATICN TACTICAL signal during tactical operations, and they are invalidated by the absence of the validation signal "> 3 METERS" 'when the aircraft is below 3 meters radio altitude IL door 32 is validated by a signal TRAIN RENTER when the landing gear of the The aircraft is retracted so as to place the system under the control of the "retracted train" comparator. The AND gate 34 is enabled by the TRAIN OUT signal to place the system under the control of the "outgoing train" warning comparator 18 when the The landing gear 32 is further disengaged by an OR gate 36 in various flight conditions, among which are the anti-mine countermeasure conditions and the maneuvering conditions. and if the pilot wishes to

  deactivate the landing gear warning retracted The disabling function is provided by the CUAM countermeasures signal, the TRAIN RENTER signal and the TACTICAL INVALIDATION signal.

  When the aircraft is flying with its landing gear retracted and not in a take-off mode, while the other validation conditions have been satisfied, the AND gate 32 is under control of the warning comparator 30. recessed gear 16 which produces the warning trigger signal and applies it through gate 32 to a first voice generator 38 and an AND gate 40, whenever the criteria indicating insufficient clearance from the As long as the airspeed of the aircraft is less than a predetermined airspeed, for example 120 knots, the AND gate 40 is disabled, which prevents the application of the warning trigger signal to The first warning generator 38 responds to the warning trigger signal received by the AND gate 32 and produces a voice signal, such as "TOO LOW, TRAIIH RENT RE ", and applies it to a transducer 44, which may be a loudspeaker, earpiece, or the like, to give a voice warning to the pilot. Although Figure 1 shows a configuration in which the

  If the signal of the generator 38 is applied directly to the transducer 44, the signal can also be applied indirectly, for example via the intercom system of the aircraft.

  When the airspeed of the aircraft exceeds a predetermined airspeed, such as 120 knots, indicating that the aircraft is in cruise flight and not in a landing mode, the ET-40 is validated by the signal "> 120 KNOTS" This allows the application of the warning trip signal from the AND gate 32 to the TOO LOW warning generator, SOL 42, to produce the warning "TOO LOW, SOIL" and 44 Generator 42 also disables generator 38 when the warning "TOO LOW, SOIL" is generated, to avoid confusing the pilot Thus, when the aircraft speed is less than 120 knots , which indicates a landing, any warning product will be the warning "TOO LOW, TRAIN RETURN" At airspeed greater than 120

  knots, which indicates a cruise flight mode, any warning produced will be the warning "TOO LOW, SOIL".

  When the landing gear is out, the AND gate 32 is disabled and the AND gate 34 is enabled to thereby place the warning generator TOO LOW, SOL 42 under the

  control of the warning comparator "TRAIN OUTPUT" 18, 35 via the AND gate 34.

  warning signs will be determined by the comparator

  "out of gear" warning 18, and any warnings produced will be warned "TOO LOW, SOIL".

  In the embodiment shown, the "retracted train" warning indicator 16 and the "outgoing train" warning comparator 18 have been represented as two separate comparators; however, both functions can be implemented in a signal comparator whose warning criteria are changed according to the landing gear in or out position. Similarly, the warning generator TOO LOW, TRAIN RENTER 38 and the warning generator TOO LOW, SOL 42 are shown as two separate warning generators, but one can also use a single warning generator capable of producing two

separate warnings.

  Hatched areas in Figure 2 represent the radio altitude-speed relationships that are required to produce an Au-20 warning under an air speed of approximately 120 knots, the warning "TOO LOW, TRAIN RETURN" "is produced, and above an airspeed of about 120 knots, it is the warning" TOO LOW, SCL "that is produced below an airspeed of about 40 knots, The warning "TOO LOW, TRAIN RENTRE" 25 is produced when the altitude of the aircraft above the ground drops below about 45 m The altitude required to produce the warning decreases linearly according to air velocity above about 40 knots, until an airspeed of about 120 knots is reached, and at this point the warning "TOO LOW, TRAIN RETURN" is produced at uhe altitude about 23 m above the ground The particular shape of the curve is to maximize the warning time when the pilot lands actually, and to minimize unwanted warnings during low altitude maneuvering, as such maneuvers are generally performed at airspeeds greater than about 40 knots above an airspeed. At approximately 120 knots, the warning "TOO LOW, SOIL" is generated whenever the radio altitude falls below about 23 m, regardless of the airspeed, provided that the airspeed is greater than about 120 nodes. The hatched portion of the graph of FIG. 3 shows the relationship between the radio altitude and the airspeed that is required to produce a warning in the "out of train" mode of operation. Because the landing gear is already out. , no warning "TOO LOW, TRAIN RENTER" is produced, and the only warning that is produced is "TOO LOW, SOIL" Above an airspeed of about 120 knots, descending below radio altitude of about 30 m makes the warning appear. This altitude is a little higher than the altitude required to produce the warning in the event that the landing gear has returned, because the helicopters have typically landing gear when operating at low altitude Below about 120 knots airspeed, the altitude at which the warning is produced decreases linearly until the warning altitude 25 is reduced to 3 m at an air speed of 58 knots No warning is given below an airspeed of 58 knots, to allow maneuvers at low altitude and at low speed without making any apparent difference. Unintentional warnings The warnings are also disabled below 3 m radio altitude for operating modes with the landing gear retracted as with the landing gear extended to avoid false warnings generated by signals.

  erratic radio altitude at low altitudes. It goes without saying that many modifications can

  can be made to the device described and shown, without departing from the scope of the invention.

Claims (9)

  A ground proximity warning system for alerting the pilot of a wing aircraft to the extent of insufficient clearance from the ground, comprising: means (16, 18); , 28) for receiving a signal representative of the airspeed-the aircraft; means (16, 18, 30) for receiving a signal representative of the altitude of the aircraft above the ground; and means (32, 34, 38, 40, 42, 44) which operate in dependence on the air-velocity and altitude signal signal receiving means (16, 18, 28, 30) so as to produce a warning if the altitude of the aircraft above the ground is insufficient for the airspeed at which the aircraft is flying, these warning generating means including means for producing the aircraft. warning at a first altitude for a first airspeed, and to produce the warning at a second altitude, lower than the first, for a higher airspeed. Warning system according to claim 1, characterized in that the warning means (32, 34, 38, 40, 42, 44) comprise means for producing a first warning if the aircraft is flying below 'a   predetermined airspeed, and a second warning of the first if the aircraft is flying above the predetermined speed.   Warning system according to claim 1, characterized in that the warning generating means comprises means for generating the warning at an altitude of about 45 m above the ground, if the airspeed aircraft is less than about 40 knots, and to produce the warning at an altitude of about 23 m when the airspeed of the aircraft is greater than about nodes.   4 Warning system according to claim 1 1 3, characterized in that the altitude required to produce a warning decreases linearly between a speed of about 40 knots and an airspeed of about 120 knots. Warning system according to claim   4, characterized in that it comprises means (32, 34) for preventing the generation of a warning at altitudes below about 3 m above the ground.   Warning system according to claim 10, characterized in that the warning generating means (32, 34, 38, 40, 42, 44) comprise means for producing a first warning when the aircraft is flying at airspeeds below about 120 knots, and to produce a second warning, distinct from the first,   when the aircraft is flying at airspeeds greater than about 120 knots.   Warning system according to claim 1, characterized in that it further comprises means   (20, 22, 24) for biasing the generation of warning when the aircraft takes off.   8 warning system according to claim 1, wherein the aircraft comprises a landing gear that can be moved between a retracted position and an extended position, characterized in that it comprises means (32, 34) for receiving a signal representative of the position of the landing gear of the aircraft, and in that the warning generation means operate under the control of the means providing a position signal of the landing gear so as to modify the altitudes at which the warning is produced, so that the altitude   above the ground at which the warning is produced increases with airspeed.   9 Proximity warning system for alerting the pilot of a rotary wing aircraft 35 of the existence of insufficient clearance with respect to the Si: sol, characterized in that it comprises: means (16 , 18, 28) for receiving a signal representative of the airspeed of the aircraft; means (16, 18, 30) for receiving a signal representative of the altitude of the aircraft 5 above the ground; and means (32, 34, 38, 40, 42, 44) operate under the control of the means providing air velocity and altitude signals, so as to produce a warning if the altitude of the aircraft by ground ratio is insufficient for the airspeed at which the aircraft is flying, these warning generating means including means (34, 40, 42) for producing a warning if the altitude of the aircraft above soil goes down below   about 30 m while the airspeed of the aircraft is greater than about 120 knots.