DE2549884A1 - WARNING DEVICE FOR A HELICOPTER - Google Patents

Description

UNITED TECHNOLOGIES CORPORATION "Λ * ^{θ n} * ^a " wa I t

Dipl .-! Ng. Rolf Menges 1 Financial Plaza son ροππο h. Munich \

Hubertusstrasse 2O · töl. O81OG / 2176

Hartford, Connecticut 06101

USA Änwaitsakte U 269

fr Nov 1975

WARNING DEVICE FOR A HELICOPTER.

25A9884

The present invention relates to a warning device for eii A helicopter that gives the pilot enough time j tail touching the ground during landing

i;

: to prevent. ;

In known devices of this type, means were provided to protect the pilot from possible contact with the ground; i to warn the tail that whenever the landing gear is extended or in landing position, the aircraft is lower than j I flew 46 m and the nose of the helicopter was raised over 10 ° with respect to the horizon. If all these criteria were met,

t;

! a tone signal was superimposed on the intercom. Of course they were

j these criteria do not necessarily indicate that

I the tail hit the ground and so these criteria could be

, a normal landing must be met. That is why the signal was

'was given anyway and was a cause for concern for the pilot. '· ■

j The present invention seeks to generate a warning signal only when

• when the tail is about to come into contact with the ground and normal

j Landing cannot take place without a correction. That's why this is

■ System designed so that it receives flight altitude and attitude signals

1 processed in such a way that when they are equal and tension and

are opposite in phase, a comparison circle

I output signal generated, which switches on a relay driver,

j that feeds the warning tone into the intercom. A signal is

I speaking of the rate of descent is also summed with and

j serves as a preload, which is proportional to the rate of descent is changed. Thus the warning becomes sufficient / before

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given the ground contact to give the pilot enough time to influence the attitude. !

The object of the present invention is a warning device for a helicopter which provides a warning signal to the pilot whenever there is a touch of the tail with the floor is imminent. According to the invention, the device comprises Means for generating a warning signal whenever the tail of the helicopter is in a position in which he could touch the ground, these means a responsive to the altitude of the helicopter device for Generating a first signal include, as well as means responsive to the attitude of the helicopter, to a second To generate a signal that responds to the two

i talking device for combining both signals into one signal whose value is with a predetermined one, the ground contact the displayed value is compared in order to excite a relay,

if there is a predetermined difference in signals, and means responsive to the rate of descent of the helicopter to shift the first signal in the direction of higher values with respect to the predetermined value proportional to the rate of descent. j

The invention will now be made with reference to the accompanying drawings / which represent a preferred embodiment of the same, for example

wisely described. In the drawings are:

Figure 1 is a schematic block diagram of a preferred embodiment the invention; j

FIG. 2 shows a graphic representation of the flight altitude as a function of the flight attitude to show the effect of the descent speed i and

Figure 3 is a circuit diagram of the preferred embodiment of the invention.

The invention can best be seen with reference to Figures 1 and 2 which illustrate a preferred embodiment thereof represent, although the details of the circuits of the

half _# I

Simplicity / and / omitted for ease of understanding:

/the ;

have been. It goes without saying that in this embodiment, although known, conventional electronic circuits , j

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are preferred, the invention can also be understood with the aid of other media, which is easily recognizable for the person skilled in the art is.

Signals according to the angle of attack and the altitude of the helicopter are generated by a commercially available vertical gyro and a commercially available radar altimeter and processed in a height warning circuit 10, which is shown as a schematic block diagram.

From Figure 1 it can be seen that the signal of the vertical gyro 14 is an AC voltage error signal, which in a demodulator 16 is converted into a DC voltage amplitude signal. All signals that indicate that the bow of the helicopter pointing downwards and which could otherwise trigger the warning signal are switched off by this circuit. ,

The demodulated signal of the angle of attack of the helicopter is then amplified in an amplifier 18, which one of the pitch of the helicopter generates a proportional signal.

According to Figure 1, the radar altimeter 22 generates a signal which is usually a DC voltage signal which is divided into three; Directions is passed, namely to a proportional | Amplifier 24, a descent rate amplifier 26, and an altitude switch-off circuit 28. Both the amplification of the proportional

the ;

Functional amplifier 24 as / of the descent rate amplifier 26 are precalculated to the comparator 20 at different Operate descent rates compared to the helicopter attitude. j

Also are provided in the warning circuit means to ensure that the warning signal is not turned on, always \ when the pitch of the helicopter or aircraft is such that the tail of the same soil would while not touch a j normal landing ensure. A blocking logic 21, j

which is responsive to the output signal of the amplifier 18, si- ■ ensures that the warning signal is never switched on if the pitch is below an angle of e.g. 8.5 °.

The output signal of the proportional amplifier 18, the proportional amplifier 24 and the descent rate amplifier 26 are summed in a summing unit 30, which is an output

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output signal is only generated if the voltage and phase of the

Altitude signal and the signal from the longitudinal tilt (attitude) which ^appear: other are equal and opposite. The summing unit 30
is, as can be seen from Figure 1, biased by the output signal of the descent rate amplifier 26 so that it
The amplitude signal is shifted to higher values as a function of the descent rate of the helicopter. This signal
Prevents contact with the ground by measuring the rate of descent. . j

This can be seen more clearly from FIG. 2, which shows a graphic representation of the flight altitude as a function of the flight attitude.
The actual contact with the ground by the tail is shown by the dashed line A. The minimum line B (ground level) represents the value at which the comparison circuit the 'relay driver 32 (Figure 1) supplies a signal to either the i audible or visual display 34, and 36, respectively, or turn both of them. This line is shown as a function of an increase. the descent rate (calculated by the descent rate amplifier 26) of the helicopter shifted upwards,
so that B ¹ represents when a warning is given at a descent speed of 5 m per second and B ¹ 'when a warning is given

a descent speed of 10 m per second,

etc. The purpose of the altitude shutdown circuit 20 is unintentional

To prevent activation of the warning signal above a certain maximum height of 150 m, for example. This means that the warning signal can be triggered at any time below 150 m and when it comes into contact with the ground. ■ ^;

Circuitry for practicing the invention is built and

has been tested and is shown in FIG. A suitable. The commercially available radar altimeter 38 produces a chip! voltage drop at an input resistor 40 as a function of height; This signal is amplified by the operational amplifier 42 and ί applied to a resistor 46. The gain of the amplifier | 42 is ΐίοη the resistance selected as input resistance 40 '

. i

stood and a feedback resistor 44 is determined. The output signal at resistor 46, which is always positive with respect to the
An altitude input signal is fed to a summing point 48.

609840/0284

A suitable, commercially available pitch gyro 50, which is one of the pitch of the aircraft proportional alternating voltage signal is generated at an input resistor 52 connected, a demodulator 54 being interposed. After amplification of the input resistor 52 occurring signal by means of a suitable operational amplifier, this signal is fed to a resistor 56, so that the voltage drop across it is proportional to the pitch of the aircraft. The gain of amplifier 58 is from Input resistor 52 and a feedback resistor 60 set. Thus, the voltage drop across resistor 56 is the attitude of the aircraft proportionally. If its amplitude and polarity match the polarity of the flight altitude signal at the connection point is equal and opposite, the input signal to the comparison circuit 63 becomes negative with respect to the connection point 62 and pass through amplifier 64 to be applied to base 66 of transistor 68.

The output of the blocking logic 70 is connected to the connection point and always carries such a signal _/ that has its polarity

is Q

did negative / if the pitch is less than 8.5 when raised Bug is. The output signal of the amplifier 58 is also fed to a resistor 72 and, if it is equal and opposite

■.

j resets the signal on resistor 74, becomes the polarity of the j output of the amplifier 76 of the blocking logic 70 the negative

Neutralize the signal at connection point 62. This can do that.,

Output signal at the amplifier 64 of the comparison circuit 63 the

! Turn on base 66 of transistor 68 every time it is positive j with respect to the input of amplifier 64.

! The rate of change in flight altitude is measured by means of an RC circuit 90, which consists of the series connection of a resistor 92 and a capacitor 94 consists. This signal is amplified and _eineni by a suitable operational amplifier 96 Resistor 98 supplied. The voltage drop across resistor 98 is therefore proportional to the rate of descent of the aircraft ' and is fed to the summing point 48 to the signal of the height and,

is to bias attitude. As can be seen from FIG. 2 / this is used for this to shift curve B upwards as a function of the rate of descent. The gain of the operational amplifier 96 becomes

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by the input resistance 94 and the feedback resistance was 95 determined.

The light and / or the horn are switched on by a relay 86 with a coil 84 which actuates a contact arm 86. Then base 66 is positive. This turns on the relay driver 68 a, energizing the coil 84, and connects the horn or the light with a 28 volt voltage source. I.

The voltage divider consisting of the resistors 97, 99 and 100 is connected to a 15-volt direct voltage source and operates the output of the resistor 40 before to a lower limit for the Define curve B of FIG.

What has just been described is simple but effective Device for triggering a warning signal to provide sufficient time to enable the pilot to make a corrective Take action to prevent the stern propeller from touching the ground. This invention avoids the constant Warning which would occur if the warning device were actuated when two predetermined variables were reached., as has been the case with known devices up to now. 1

609840/0264

Claims (5)

PATENT CLAIMS j 1. Warning device for a helicopter with a tail rotor, characterized by means (10) for providing a warning signal whenever the stern is in a position ', where it could touch the ground, the means (10) having a first one responsive to the altitude of the helicopter
Signal generating device (22), one on the attitude of the
Helicopter responsive, a second signal generating device (14), a responsive to the first and the second signal, combining the two signals and with a ground contact representing a predetermined value comparing device (30,20), which a relay (32) when a predetermined excited _f
Difference is reached / and comprise a device (30) responsive to the descent rate of the helicopter for shifting the first signal to higher values with respect to the predetermined value proportional to the descent rate. 2. Warning device according to claim 1, characterized in that ■ that the device comprises electronic circuits and the
The value of the combined signal at which the relay (32) is energized is present when the first and second signals are opposite and equal to each other. ι 3. Warning device according to claim 1 or 2, characterized; indicates that the relay (32) an acoustic and / or optical Warning device for the pilot of the helicopter actuated. ί 4. Warning device according to claim 1 to 3, characterized
by a device responsive to the altitude of the helicopter for blocking the actuation of the relay above a predetermined altitude. 5. Warning device according to one of claims 1 Jbis4, characterized by responsive to the attitude of the helicopter
Device for preventing the relay (62) from being energized in a certain flight position. 609840/0264 Blank page