FI74254B - VARNINGSSYSTEM FOER FOER HOEG SJUNKHASTIGHET FOER ETT TAKTISKT FLYGPLAN. - Google Patents

Description

1 74254

Excessive rate of descent warning system for a tactical airplane

The present invention relates generally to ground warning systems, and more particularly to a system according to the preamble of claim 1 which, in the approach phase of a flight, warns the pilot of a tactical aircraft such as a fighter or combat aircraft if the aircraft descent speed is excessive at an altitude .

Systems are already known which provide a warning to the pilot of an aircraft in the event that the aircraft sinks too quickly when approaching. Typical of these systems are those disclosed in U.S. Patent Nos. 3,946,358, 3,947,808, 3,958,219, and 4,215,334, all of which are incorporated herein by reference.

Although all of the above systems 20 perform the basic function of alerting the pilot if the aircraft's rate of descent exceeds a predetermined safe speed determined by the aircraft's radio altitude, the above systems are designed to operate in commercial aircraft, particularly large jet-25 turbine aircraft of the type operated by commercial airlines. Because the flight profiles of such aircraft are typically significantly different from tactical aircraft, such as a fighter aircraft or a land fighter aircraft landing on 30 aircraft carriers, systems designed for commercial aircraft are not effective on tactical aircraft because they tend to generate false warnings, thus losing significance. .

Thus, it is an object of the present invention to provide a proximity warning system which overcomes many of the disadvantages of the prior art warning systems.

It is a further object of the present invention to provide a warning system for the pilot of an approaching tactical aircraft which warns if the rate of descent of the aircraft is excessive at the altitude at which the aircraft is flying.

It is still a further object of the present invention to provide a ground warning system to alert a pilot of a tactical aircraft if his rate of descent on approach is dangerously high, the warning criteria being selected to suit the mode of operation of that tactical aircraft.

The set objects are achieved by a warning system according to the invention, which is characterized by what is set forth in the characterizing part of claim 1.

Briefly, in accordance with a preferred embodiment of the invention, a system is provided that monitors the rate of descent of 20 aircraft when the landing gear is low, the indicated airspeed is less than 300 knots (562 km / h) and armament is ensured, and provides an audible warning to the pilot if pressure altitude -25 at the speed at which the airplane flies.

These and other objects and advantages of the invention will become readily apparent upon consideration of the following detailed description and accompanying drawings, in which: Figure 1 shows a logic block diagram of a warning system according to the invention; and Figure 2 shows a diagram of the rate of change of pressure altitude as a function of radio altitude required to generate a warning.

Referring now to the drawings, and in particular to Figure 35 1, there is shown an embodiment of a proximity warning system 3 74254 according to the invention, generally designated 10. The system 10 of the invention is shown in Figure 1 as a logic block diagram for gates, comparators and the like; however, it should be understood that the actual implementation of the logic may be different from that shown in Figure 1, with several digital and analog implementations possible. The signals used by the described system include radio altitude, pressure altitude change-10 rate, airspeed, and signals indicating the position of the landing gear and whether the armament is tuned, as well as multiple eligibility signals. Depending on the type of aircraft on which the warning system is installed, the signals shown in Figure 1 may be obtained from individual gauges 15 such as altimeter 12, altitude rate circuit 14, radio altimeter 16, airspeed signal source 18 such as ADC calculators, whether the armament is tuned-20 and whether the wheels have weight. Alternatively, signals can be obtained from the digital data bus on certain newer aircraft.

Because this system is designed to operate only during the pre-landing approach of the flight profile, it is prevented from operating during other phases of the flight to avoid the possible development of false warnings during those phases. The blocking operation is performed by a pair of AND gates 20 and 22, which monitor a number of flight situations and the movement of the aircraft to determine if the aircraft is approaching for landing. The two parameters monitored by the gate 20 are whether the landing gear is down and whether the wheels have a weight. In addition, a signal indicating whether the armament is armed is fed to the gate 20, because during normal landing situations 35 the armament should not be armed. If the armament had been tuned 4 74254, it would indicate that the airplane is operating at a stage other than the pre-landing approach. In addition, the airspeed is monitored by a comparator 24, which provides a signal to the AND gate 20 when the airspeed is less than 300 sol-5 mua (562 km / h), indicating a probable landing situation. In addition, signals indicating that the radio altitude signal and pressure altitude signals are not blocked are applied to the AND gate 22 to prevent the development of warnings in the event of a faulty pressure or radio altimeter.

In addition, to further reduce the likelihood of false alarms, the system is prevented below 50 feet (15.2 m) radio altitude and 1000 feet (305 m) radio altitude by comparator circuit 26, which is opposite to signals from radio altimeter 16 and provides enable signals to AND gate 22. only when the airplane is between 50 ft (15.2 m) and 1000 ft (305 m) radio altitude.

If all of the above conditions are met, the I-gate 22 and the OR gate 28 are brought under the control of comparators 30 and 32. The comparators 30 and 32 are responsive to radio altitude pressure altitude change rate signals and supply the signal to the OR gate 28. when the rate of descent is too high at a certain radio altitude. Upon receiving the signal from the OR gates 30 or OR gates 32, the gate 28 causes the gate 22 to supply a warning start signal to a warning circuit such as a digital audible warning generator 34. This causes the alert generator 34 to generate a digitally generated audible signal such as "SINK RATE" and either directly or indirectly to transducer 36, which may be a loudspeaker, earphone, or the like.

In the illustrated embodiment, two comparators 30 and 32 are used to determine the required rate of change of pressure altitudes and radio altitude "SINK RATE" - 5 74254 to generate a warning, but one comparator may also be used. However, due to the particular shape of the warning curve shown in Figure 2, it has been found practical to use two separate comparators. Comparator 5 is used to initiate warnings at low radio altitudes and subsidence rates below 3000 ft / min (914 m / min), while comparator 32 is used to initiate warnings at subsidence rates above 3000 ft / min (914 m / min). Thus, the comparator 32 monitors the signal from the pressure altitude change-10 rate circuit 14 and compares it to a reference signal representing a 3000 ft / min (914 m / min) descent rate applied to the second pole of the comparator 32. Whenever the signal from the speed circuit 14 exceeds the reference signal representing the descent rate of 3000 ft / min (914 m / min) 15, the comparator 32 supplies a signal to the OR gate 28. This signal causes the OR gate 28 to allow the AND gate 22, and causes alert development. At descent speeds below 3000 ft / min (914 m / min), the comparator 30 controls and provides warning generation 20 as a function of both pressure descent rate and radio altitude according to a two-part curve at radio altitudes below 600 ft (183 m) and at descent rates below 3000 ft / min (914 m / min). at speeds as shown in Figure 2. The "SINK RATE" warning is generated when the rate of descent exceeds 3000 ft / min 25 (914 m / min) at 600 ft (183 m) radio altitude, when the rate of descent exceeds 2500 f / min (762 m / min) at 200 ft / min (m) At radio altitude, and when the rate of descent exceeds 1250 ft / min (381 m / min) at 50 ft (15.2 m) radio altitude.

The above-described relationship between the pressure altitude change rate and the radio altitude required to generate a warning is shown in more detail in Figure 2. The shaded area within the curve of the diagram in Figure 2 shows several relationships between descent rate and radio altitude values that cause a "SINK RATE" warning. This warning model is determined by the flight characteristics of 74254 fighter or grenade bombers, such as the "Fairchild AIO", and the manner in which those aircraft are flown during the landing phase of the flight. Because these airplanes often fly at relatively low altitudes and may experience relatively high subsidence rates during such low altitude flights, the upper part of Figure 2 is limited to 1000 ft (305 m) to avoid false warnings during movements above 1000 ft (305 m). . This results in 10 significantly different models compared to the model used in commercial aircraft, where warnings are allowed up to an altitude of about 2450 feet (747 m). In addition, the allowable descent rates at lower altitudes are substantially higher for tactical aircraft 15 than for commercial aircraft. For example, the warning pattern shown in Figure 2 always allows a descent speed of 2500 ft / min (762 m / min) at an altitude of 200 ft (61 m), while the warning system used in commercial aircraft generates a warning at a descent speed of about 20 to half that speed. However, at altitudes below 200 ft (61 m), the allowable rate of descent decreases rapidly at approximately 1500 ft / min (457 m / min) at 50 ft (15.2 m) above the ground to avoid landing contacts at excessive rate of descent.

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Claims (8)

A warning system (10) for entering an approaching aircraft equipped with a retractable landing gear to warn the pilot when the aircraft sinks too fast, comprising first activating means (20) which, in response to a signal representing the landing gear position, activates said warning only when the landing gear is down, and a warning means (22, 30, 34, 36) which, in response to signals representing the altitude of the aircraft above the ground (16), the rate of descent of the aircraft (14) and the position of the landing gear (20), generates a warning if the aircraft is about 305 m below the ground and its rate of descent exceeds about 914 m / min, characterized by signaling means (18) for producing a signal representative of the airspeed of the aircraft; a second Akti actuating means (24) for activating said warning when the airspeed is below a predetermined airspeed. A warning system according to claim 1, characterized in that the warning means (22, 30, 34, 36) generates a warning at descent speeds of less than about 914 m / min when said aircraft is at an altitude of about 183 m above the ground. Warning system according to claim 2, characterized in that the warning means (22, 30, 34, 36) generates a warning when the rate of descent exceeds about 762 m / min at a height of about 61 m above the ground, the rate of descent required to generate the warning increases with the altitude above until a rate of descent of about 914 m / min is required to generate a warning at a height of about 183 m above the ground. A warning system according to claim 3, characterized in that the warning means (22, 30, 35 34, 36) generates said warning when said descent speed exceeds about 457 m / min at a height of about 15.2 m above ground level, said descent speed , which is required to generate a warning, increasing with altitude above ground level until a rate of descent of about 762 m / min is required to generate a warning at an altitude of about 61 m 5 above ground level. Warning system according to claim 4, characterized in that said rate of descent increases linearly with height between 15.2 m and 61 m above the ground and between 61 m and 183 m above the ground. A warning system according to claim 1, characterized by means (26) for generating a warning when the height of the aircraft is less than about 15.2 m above the ground. A warning system according to claim 1, characterized in that said predetermined air speed is about 562 km / h. 7 74254 A warning system according to claim 1, characterized in that said aircraft is armed and that the warning means (22, 30, 34, 36) is responsive to the confirmation of the aircraft's armament to activate the development of said warning only when the armament is unsecured. i 9 74254