CA1072195A - Helicopter warning system - Google Patents
Helicopter warning systemInfo
- Publication number
- CA1072195A CA1072195A CA239,974A CA239974A CA1072195A CA 1072195 A CA1072195 A CA 1072195A CA 239974 A CA239974 A CA 239974A CA 1072195 A CA1072195 A CA 1072195A
- Authority
- CA
- Canada
- Prior art keywords
- helicopter
- signal
- voltage
- voltage signal
- altitude
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C5/00—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels
- G01C5/005—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels altimeters for aircraft
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Emergency Alarm Devices (AREA)
- Navigation (AREA)
- Radar Systems Or Details Thereof (AREA)
Abstract
Abstract of the Disclosure To prevent inadvertent ground contact of the tail of a helicopter during a landing operation without providing a continuous warning signal for normal landings the altitude and attitude signals are scaled such that when they are equal and opposite in voltage and phase compared to a ground contact curve the comparator will energize a relay for actuating a pilot warning signal. A rate of descent signal biases the altitude signal upward varying in proportion to rate of descent as to enable the pilot to have sufficient warning time to take corrective action.
Description
~7~19~
BACKGROUND OF THE INVENTION
This invention relates to helicopters and particularly to a warning system that provides sufficient time for the pilot to avoid a tail contact during a landing operation.
Heretofore, the helicopter provided means for warning the pilot of a potential tail contact whenever the wheels are in the down or landing position, the aircraft is below 150' and the nose of the helicopter is above 10 referenced with the horizon. When all of these criteria were met, a sound signal was imposed in the intercom system. Obviously, these criteria were not necessarily indicative of the tail striking and as a matter of fact the criteria could exist--for a normal landing approach. Hence, the signal nonetheless was actuated and has been a cause of annoyance to the pilot.
Our invention contemplates providing a warning signal solely when a tail contact is imminent and a normal landing cannot ensue without corrective action. Hence, our invention --is designed to scale the altitude and attitude signals such that when they are equal and opposite in voltage and phase the comparator will trip turning on a relay driver which will cause the warning note to be applied to the intercom system.
A rate of descent signal is also summed serving to bias the line upward varying in proportion to the rate of descent.
Thus, sufficient warning prior to tail contact will allow pilot sufficient time to remedy the situation.
BACKGROUND OF THE INVENTION
This invention relates to helicopters and particularly to a warning system that provides sufficient time for the pilot to avoid a tail contact during a landing operation.
Heretofore, the helicopter provided means for warning the pilot of a potential tail contact whenever the wheels are in the down or landing position, the aircraft is below 150' and the nose of the helicopter is above 10 referenced with the horizon. When all of these criteria were met, a sound signal was imposed in the intercom system. Obviously, these criteria were not necessarily indicative of the tail striking and as a matter of fact the criteria could exist--for a normal landing approach. Hence, the signal nonetheless was actuated and has been a cause of annoyance to the pilot.
Our invention contemplates providing a warning signal solely when a tail contact is imminent and a normal landing cannot ensue without corrective action. Hence, our invention --is designed to scale the altitude and attitude signals such that when they are equal and opposite in voltage and phase the comparator will trip turning on a relay driver which will cause the warning note to be applied to the intercom system.
A rate of descent signal is also summed serving to bias the line upward varying in proportion to the rate of descent.
Thus, sufficient warning prior to tail contact will allow pilot sufficient time to remedy the situation.
-2-SUMMARY_OF THE INVENTION
An object of this invention is to provide means to improve the warning signal to the pilot of a helicopter when-ever ground contact of the tail is imminent.
A further object of this invention is to trigger a warning signal whenever the voltage and phase of the attitude and altitude are equal and opposite in value referenced to a precalculated ground contact reference line that is biased as a function of helicopter rate of descent.
In accordance with one embodiment of the invention,, there i5 provided, for a helicopter of the type that includes a tail stabilizer or tail skid, means for providing a warning signal solely when the tail is in a position that it might contact the ground, and for avoiding the signal when the hel-icopter lands normally, said means including a first operational amplifier providing a first voltage signal that is proportional to helicopter altitude, a second operational amplifier for providing a second voltage signal that is proportional to a helicopter attitude, a voltage comparator responsive to said - -first and second voltage signals, audio or visual warning means responsive to said comparator for being actuated whenever the voltage of ~aid first voltage signal is equal to and opposite in polarity from said second voltage signal, and a third oper-ational amplifier responsive to the rate of descent of said helicopter for producing a biajs voltage on said first voltage signal.
Other features and advantages will bè apparent from the specification and claims and from the accompanying drawings which illustrate an embodiment of the invention.
BRIE_ DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic and block diagram representing the preferred embodiment of this invention.
~07Z~9s Fig. 2 is a graph plotting the altitude V9 attitude - and illustrating the aspect of rate of descent.
Fig. 3 is a circuit diagram of the preferred embodiment.
DESCRIPTION OF THE PREEERRED EMBODIMENT
The invention can best be understood by referring to Figs. 1 and 2 which illustrate the preferred embodiment al-though the detailed circuitry is omitted for the sake of simplicity and convenience. It is to be understood that in this embodiment while the well known conventional electronic circuitry is preferred as one skilled in the art will appreciate this invention can be practiced with the utilization of other mediums.
;^,~ a ~ - 3a -... .. , ._ . .. .
10'7Zi9S
Signals indicative of the helicopter's pitch and altitude by a commercially available vertical gyroscope and a commercially available radar altimeter are processed by the altitude warning network shown in the block diagram generally illustrated by numeral 10.
As can be seen by referring to Fig. 1 the vertical gyro pitch signal illustrated by block 14 is an AC error signal which is processed by demodulator 16 to a DC
magnitude signal. All signals indicative of a nose down condition of the helicopter which could otherwise trigger the warning signal is rejected by this circuitry.
The demodulated pitch signal is then amplified by the amplifier 18 which produces a signal proportional to the pitch a,ttitud,e of the aircraft.
Also noted from a viewing of Fig. 1 the radar altimeter height signal represented by block 22 which is conventionally a DC signal is routed in three directions, a) to the proportional amplifier 24, the rate of descent amplifier 26 and the altitude cut-off circuit 28. Both the gains of the proportional and rate of descent amplifiers 24 and 26 are precalculated to satisfy comparator actuation at various rates of descents as compared to helicopter attitude.
Additionally, the warning network provides means for assuring that the warning signal is not actuated whenever the pitch of the aircraft is such that the tail would not contact the ground during a normal landing approach. Inhibit logic circuit represented by block 21 responding to the output of amplifier 18 assures that the warning signal is never actuated when-t~e pitch is below a predetermined angle of say 8.5.
' `' ~0~2195 The output of proportional amplifier 18, proportional amplifier 24, and rate of descent amplifier 26 are summed in summer 30 which is the input to comparator 20. The comparator 20 in turn produces an output signal solely when the voltage and phase of the altitude and pitch (attitude) signals are equal and : opposite. The summer 30 is biased, as noted from Fig. 1, by the output of rate of descent amplifier 26 so that the altitude signal is shifted upwardly as a function of the rate of descent -. of the helicopter. This signal `anticipates contact by measuring rate of descent.
This is more apparent b~ a view of Fig. 2 which is a graphical representation of altitude vs attitude. As noted, the actual tail contact is represented by the dash line A. The minimum line B (ground level) is indicative of the value when -i- the comparator will trigger a signal to the relay driver 32 (Fig. 1) to actuate either the audio or visual indicators 34 and 36 respectively or both. This line is shifted upwardly as a function of an increase in rate of descent (calculated by the ; rate amplifier 26) of the helicopter. Hence B' represents when warning occurs at a 1000 FPM rate of descent and B ' when a 2000 FPM rate of descent, etc.
The purpose of the altitu~e cut-off 28 is to prevent the warning signal from being inadvertently actuated above some predetermined maximum altitude, say ~00'. Hence the warning signal can occur anyeime ~elow S00' and touchdown.
,~ ` .
:B ` - 5 -107'~19~
Circuitry embodying this invention has been built and flight tested which circuitry is shown in Fig. 3. As noted in Fig. 3 a suitable commercially available radar altimeter 38 produces a voltage drop across input resistor 40 as a function of altitude. This signal is amplified by the operational amplifier 42 and applied across resistor 46.
The gain of amplifier 46 is established by the resistance selected for input resistor 40 and feedback resistor 44.
The output of resistor 46 which is always positive with respect to the altitude input signal is applied to the summation junction 48.
; A suitable commercially available pitch vertical gyro 50, which produces an AC signal proportional to the pitch of the aircraft is applied to input resistor 52 after being demodulated by a suitable commercially available demodulator 54. This signal after being amplified by a suitable operational amplifier 58 is applied to resistor 56 so that its voltage drop is proportional to the pitch of the aircraft.
The gain of amplifier 58 is established by input resistor 52 and feedback resistor 60. Hence, the voltage drop across resistor 56 is proportional to the altitude of the aircraftp When its magnitude and polarity is equal and opposite to the polarity of the altitude signal at junction 48 the input to the comparator 63 will be negative with respect to junction point 62 and pass through amplifier 64 to be applied to the base 66 of transistor 68.
.~
107~195 The output of inhibit logic circuit 70 is applied to junction point 62 and is always such that its polarity is - negative when the attitude is say below 8.5 nose up condition. Hence the output of amplifier 58 is also applied across resistor 72 and when it is equal and opposite to the output of resistor 74 the polarity of the output of ampli ffer 76 of the inhibit logic circuit 70 will neutralize the negative signal at junction 62. This permits the output of amplifier 64 of comparator circuit 63 to turn on base 66 of transistor 68 whenever it is positive with respect to the input of amplifier 64.
The rate of change of altitude is sensed by the R - C
circuit 90 which comprises the serially connected resistor 92, capacitor 940 This signal is amplified by suitable operational amplifier 96 and applied to resistor 98. The voltage drop across resistor 98 is hence, proportional to the rate of descent of the aircraft and is applied to summation junction 48 to bias the altitude and attitude signal. As shown in Fig. 2, this serves to shift the curve B upwardly as a function of rate of descent. The gain of operational amplifier 96 is obtained by the values of input resistor 94 and eedback resistor 95.
The light and/or horn are actuated by the relay 86 consisting of coil 84 operating contact arm 860 Hence when the base 66 is positive. This turns on the relay driver 68, actuating coil 84 and connecting the horn and light to the 28 voltage source.
107~195 The voltage divider consisting of resistors 97, 99 and 100 connected to the 15 DC voltage source biases the output of resistor 40 to establish the lower limit of curve B of Fig. 2.
What has been shown by this invention is a simple, yet effective means for actuating a warning signal to provide adequate time to permit the pilot to take corrective action so as to avoid the tail propeller from contacting the ~ ground. This concept avoids the constant warning that would occur if the warning device was actuated upon reaching two predetermined variables as was the heretofore situation.
It should be understood that the invention is not limited to the particular embodiments shown and d~scribed herein, but that various changes and modifications may be made without departiag from the spirit or scope of this novel concept as defined by the following claims.
'
An object of this invention is to provide means to improve the warning signal to the pilot of a helicopter when-ever ground contact of the tail is imminent.
A further object of this invention is to trigger a warning signal whenever the voltage and phase of the attitude and altitude are equal and opposite in value referenced to a precalculated ground contact reference line that is biased as a function of helicopter rate of descent.
In accordance with one embodiment of the invention,, there i5 provided, for a helicopter of the type that includes a tail stabilizer or tail skid, means for providing a warning signal solely when the tail is in a position that it might contact the ground, and for avoiding the signal when the hel-icopter lands normally, said means including a first operational amplifier providing a first voltage signal that is proportional to helicopter altitude, a second operational amplifier for providing a second voltage signal that is proportional to a helicopter attitude, a voltage comparator responsive to said - -first and second voltage signals, audio or visual warning means responsive to said comparator for being actuated whenever the voltage of ~aid first voltage signal is equal to and opposite in polarity from said second voltage signal, and a third oper-ational amplifier responsive to the rate of descent of said helicopter for producing a biajs voltage on said first voltage signal.
Other features and advantages will bè apparent from the specification and claims and from the accompanying drawings which illustrate an embodiment of the invention.
BRIE_ DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic and block diagram representing the preferred embodiment of this invention.
~07Z~9s Fig. 2 is a graph plotting the altitude V9 attitude - and illustrating the aspect of rate of descent.
Fig. 3 is a circuit diagram of the preferred embodiment.
DESCRIPTION OF THE PREEERRED EMBODIMENT
The invention can best be understood by referring to Figs. 1 and 2 which illustrate the preferred embodiment al-though the detailed circuitry is omitted for the sake of simplicity and convenience. It is to be understood that in this embodiment while the well known conventional electronic circuitry is preferred as one skilled in the art will appreciate this invention can be practiced with the utilization of other mediums.
;^,~ a ~ - 3a -... .. , ._ . .. .
10'7Zi9S
Signals indicative of the helicopter's pitch and altitude by a commercially available vertical gyroscope and a commercially available radar altimeter are processed by the altitude warning network shown in the block diagram generally illustrated by numeral 10.
As can be seen by referring to Fig. 1 the vertical gyro pitch signal illustrated by block 14 is an AC error signal which is processed by demodulator 16 to a DC
magnitude signal. All signals indicative of a nose down condition of the helicopter which could otherwise trigger the warning signal is rejected by this circuitry.
The demodulated pitch signal is then amplified by the amplifier 18 which produces a signal proportional to the pitch a,ttitud,e of the aircraft.
Also noted from a viewing of Fig. 1 the radar altimeter height signal represented by block 22 which is conventionally a DC signal is routed in three directions, a) to the proportional amplifier 24, the rate of descent amplifier 26 and the altitude cut-off circuit 28. Both the gains of the proportional and rate of descent amplifiers 24 and 26 are precalculated to satisfy comparator actuation at various rates of descents as compared to helicopter attitude.
Additionally, the warning network provides means for assuring that the warning signal is not actuated whenever the pitch of the aircraft is such that the tail would not contact the ground during a normal landing approach. Inhibit logic circuit represented by block 21 responding to the output of amplifier 18 assures that the warning signal is never actuated when-t~e pitch is below a predetermined angle of say 8.5.
' `' ~0~2195 The output of proportional amplifier 18, proportional amplifier 24, and rate of descent amplifier 26 are summed in summer 30 which is the input to comparator 20. The comparator 20 in turn produces an output signal solely when the voltage and phase of the altitude and pitch (attitude) signals are equal and : opposite. The summer 30 is biased, as noted from Fig. 1, by the output of rate of descent amplifier 26 so that the altitude signal is shifted upwardly as a function of the rate of descent -. of the helicopter. This signal `anticipates contact by measuring rate of descent.
This is more apparent b~ a view of Fig. 2 which is a graphical representation of altitude vs attitude. As noted, the actual tail contact is represented by the dash line A. The minimum line B (ground level) is indicative of the value when -i- the comparator will trigger a signal to the relay driver 32 (Fig. 1) to actuate either the audio or visual indicators 34 and 36 respectively or both. This line is shifted upwardly as a function of an increase in rate of descent (calculated by the ; rate amplifier 26) of the helicopter. Hence B' represents when warning occurs at a 1000 FPM rate of descent and B ' when a 2000 FPM rate of descent, etc.
The purpose of the altitu~e cut-off 28 is to prevent the warning signal from being inadvertently actuated above some predetermined maximum altitude, say ~00'. Hence the warning signal can occur anyeime ~elow S00' and touchdown.
,~ ` .
:B ` - 5 -107'~19~
Circuitry embodying this invention has been built and flight tested which circuitry is shown in Fig. 3. As noted in Fig. 3 a suitable commercially available radar altimeter 38 produces a voltage drop across input resistor 40 as a function of altitude. This signal is amplified by the operational amplifier 42 and applied across resistor 46.
The gain of amplifier 46 is established by the resistance selected for input resistor 40 and feedback resistor 44.
The output of resistor 46 which is always positive with respect to the altitude input signal is applied to the summation junction 48.
; A suitable commercially available pitch vertical gyro 50, which produces an AC signal proportional to the pitch of the aircraft is applied to input resistor 52 after being demodulated by a suitable commercially available demodulator 54. This signal after being amplified by a suitable operational amplifier 58 is applied to resistor 56 so that its voltage drop is proportional to the pitch of the aircraft.
The gain of amplifier 58 is established by input resistor 52 and feedback resistor 60. Hence, the voltage drop across resistor 56 is proportional to the altitude of the aircraftp When its magnitude and polarity is equal and opposite to the polarity of the altitude signal at junction 48 the input to the comparator 63 will be negative with respect to junction point 62 and pass through amplifier 64 to be applied to the base 66 of transistor 68.
.~
107~195 The output of inhibit logic circuit 70 is applied to junction point 62 and is always such that its polarity is - negative when the attitude is say below 8.5 nose up condition. Hence the output of amplifier 58 is also applied across resistor 72 and when it is equal and opposite to the output of resistor 74 the polarity of the output of ampli ffer 76 of the inhibit logic circuit 70 will neutralize the negative signal at junction 62. This permits the output of amplifier 64 of comparator circuit 63 to turn on base 66 of transistor 68 whenever it is positive with respect to the input of amplifier 64.
The rate of change of altitude is sensed by the R - C
circuit 90 which comprises the serially connected resistor 92, capacitor 940 This signal is amplified by suitable operational amplifier 96 and applied to resistor 98. The voltage drop across resistor 98 is hence, proportional to the rate of descent of the aircraft and is applied to summation junction 48 to bias the altitude and attitude signal. As shown in Fig. 2, this serves to shift the curve B upwardly as a function of rate of descent. The gain of operational amplifier 96 is obtained by the values of input resistor 94 and eedback resistor 95.
The light and/or horn are actuated by the relay 86 consisting of coil 84 operating contact arm 860 Hence when the base 66 is positive. This turns on the relay driver 68, actuating coil 84 and connecting the horn and light to the 28 voltage source.
107~195 The voltage divider consisting of resistors 97, 99 and 100 connected to the 15 DC voltage source biases the output of resistor 40 to establish the lower limit of curve B of Fig. 2.
What has been shown by this invention is a simple, yet effective means for actuating a warning signal to provide adequate time to permit the pilot to take corrective action so as to avoid the tail propeller from contacting the ~ ground. This concept avoids the constant warning that would occur if the warning device was actuated upon reaching two predetermined variables as was the heretofore situation.
It should be understood that the invention is not limited to the particular embodiments shown and d~scribed herein, but that various changes and modifications may be made without departiag from the spirit or scope of this novel concept as defined by the following claims.
'
Claims (6)
1. For a helicopter of the type that includes a tail stabilizer or tail skid, means for providing a warning signal solely when the tail is in a position that it might contact the ground, and for avoiding the signal when the helicopter lands normally, said means including a first operational amplifier providing a first voltage signal that is propor-tional to helicopter altitude, a second operational amplifier for providing a second voltage signal that is proportional to a helicopter attitude, a voltage comparator responsive to said first and second voltage signals, audio or visual warning means responsive to said comparator for being actuated when-ever the voltage of said first voltage signal is equal to and opposite in polarity from said second voltage signal, and a third operational amplifier responsive to the rate of descent of said helicopter for producing a bias voltage on said first voltage signal.
2. The helicopter warning means of claim 1 including a vertical pitch gyro for producing a voltage signal propor-tional to the attitude of said helicopter.
3. The helicopter warning means as claimed in claim 2 including a demodulator for converting an alternating current produced by said vertical pitch gyro to a direct current.
4. The helicopter warning means in claim 1 including a radar altimeter for producing a voltage signal proportional to the altitude of said helicopter.
5. The helicopter warning means as claimed in claim 1 including an input resistor and a feedback resistor operatively connected to each of said first and second operational amplifiers for establishing the gain of said first and second operational amplifiers, the values of said input resistors and feedback resistors determining the operational value of turning on said operational amplifiers in relationship to the operating points of actuating the warning system with relation to the altitude and attitude of said helicopter.
6. The helicopter warning means as claimed in claim 1 including an inhibit logic circuitry including an additional amplifier biasing the output of said comparator to inhibit the voltage signal when said attitude is below a predetermined value.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/559,452 US3979717A (en) | 1974-06-03 | 1975-03-18 | Helicopter warning system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1072195A true CA1072195A (en) | 1980-02-19 |
Family
ID=24233647
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA239,974A Expired CA1072195A (en) | 1975-03-18 | 1975-11-18 | Helicopter warning system |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS5725041B2 (en) |
| CA (1) | CA1072195A (en) |
| DE (1) | DE2549884A1 (en) |
| FR (1) | FR2304515A1 (en) |
| GB (1) | GB1522506A (en) |
| IL (1) | IL48315A (en) |
| IT (1) | IT1048840B (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3228557A1 (en) * | 1982-07-30 | 1984-02-09 | Ulrich 8000 München Trampnau | WARNING DEVICE FOR HELICOPTER |
| CA1240771A (en) * | 1983-06-10 | 1988-08-16 | Noel S. Paterson | Warning system for tactical rotary wing aircraft |
| US4818992A (en) * | 1983-06-10 | 1989-04-04 | Sundstrand Data Control, Inc. | Excessive altitude loss after take-off warning system for rotary wing aircraft |
| US4769645A (en) * | 1983-06-10 | 1988-09-06 | Sundstrand Data Control, Inc. | Excessive pitch attitude warning system for rotary wing aircraft |
| DE3434758C2 (en) * | 1984-09-21 | 1986-08-07 | Ulrich 8000 München Trampnau | Helicopter landing aid |
| DE19930559B4 (en) * | 1999-07-02 | 2004-08-12 | Airbus Deutschland Gmbh | Arrangement and method for protecting an aircraft fuselage |
| DE102008058029B3 (en) | 2008-11-18 | 2010-01-07 | Deutsches Zentrum für Luft- und Raumfahrt e.V. | helicopter |
| CN113335538A (en) * | 2020-03-02 | 2021-09-03 | 中航西飞民用飞机有限责任公司 | Aircraft test flight tail wiping monitoring method |
-
1975
- 1975-10-17 IL IL48315A patent/IL48315A/en unknown
- 1975-10-30 GB GB44871/75A patent/GB1522506A/en not_active Expired
- 1975-11-06 DE DE19752549884 patent/DE2549884A1/en not_active Withdrawn
- 1975-11-12 IT IT29201/75A patent/IT1048840B/en active
- 1975-11-12 FR FR7534396A patent/FR2304515A1/en active Granted
- 1975-11-13 JP JP13674675A patent/JPS5725041B2/ja not_active Expired
- 1975-11-18 CA CA239,974A patent/CA1072195A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE2549884A1 (en) | 1976-09-30 |
| AU8573375A (en) | 1977-04-21 |
| IL48315A (en) | 1978-08-31 |
| FR2304515A1 (en) | 1976-10-15 |
| IT1048840B (en) | 1980-12-20 |
| JPS51109699A (en) | 1976-09-28 |
| GB1522506A (en) | 1978-08-23 |
| JPS5725041B2 (en) | 1982-05-27 |
| IL48315A0 (en) | 1975-12-31 |
| FR2304515B1 (en) | 1979-01-19 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |