U.S. patent application number 14/607162 was filed with the patent office on 2016-07-28 for flight instrument displaying a variable rotational speed of a main rotor of an aircraft.
The applicant listed for this patent is AIRBUS HELICOPTERS. Invention is credited to Patricia GAUTHIER, Patrick HELLIO, Setareh TAHERI, Jean-Baptiste VALLART.
Application Number | 20160214733 14/607162 |
Document ID | / |
Family ID | 56432320 |
Filed Date | 2016-07-28 |
United States Patent
Application |
20160214733 |
Kind Code |
A1 |
VALLART; Jean-Baptiste ; et
al. |
July 28, 2016 |
FLIGHT INSTRUMENT DISPLAYING A VARIABLE ROTATIONAL SPEED OF A MAIN
ROTOR OF AN AIRCRAFT
Abstract
A flight instrument that displays the rotational speed of a main
rotor of a rotary-wing aircraft, with the flight instrument
including display means, a first indicator of a setpoint for the
rotational speed of the main rotor, a second indicator of the first
current value of the rotational speed of the main rotor, and third
and fourth indicators of the limit values of the rotational speed.
The setpoint for the rotational speed of the main rotor is variable
and the first indicator is stationary on the display means, with
the second, third and fourth indicators being movable in relation
to the first indicator.
Inventors: |
VALLART; Jean-Baptiste;
(Marseille, FR) ; HELLIO; Patrick; (Bouc Bel Air,
FR) ; GAUTHIER; Patricia; (Les Milles, FR) ;
TAHERI; Setareh; (Marseille, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AIRBUS HELICOPTERS |
Marignane |
|
FR |
|
|
Family ID: |
56432320 |
Appl. No.: |
14/607162 |
Filed: |
January 28, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B64C 27/04 20130101;
B64C 27/57 20130101; B64D 43/00 20130101 |
International
Class: |
B64D 45/00 20060101
B64D045/00 |
Claims
1. A flight instrument intended for a rotary-wing aircraft equipped
with at least one main rotor, at least one motor, and at least one
set of means for determining atmospheric parameters and flight
parameters of the aircraft, including a first current value
consisting of a rotational speed of the main rotor, with the flight
instrument displaying first information about the rotational speed
of the main rotor and including: display means; at least one set of
computation means enabling the determination of a variable setpoint
for the rotational speed of the main rotor, along with at least one
lower limit and at least one upper limit of the rotational speed of
the main rotor; a first indicator of the variable setpoint for the
rotational speed of the main rotor; a second indicator of the first
current value of the rotational speed of the main rotor; and a
third indicator and a fourth indicator, corresponding respectively
to at least one lower limit and at least one upper limit of the
rotational speed of the main rotor; wherein either the first
indicator or the second indicator is represented in a fixed manner
on the display means, while the other one of the first indicator
and the second indicator is represented movably on the display
means, with the third and fourth indicators being represented
movably on the display means.
2. The flight instrument according to claim 1, wherein the first
indicator is represented in a fixed manner on the display means,
while the second indicator is represented movably in relation to
the first indicator.
3. The flight instrument according to claim 1, wherein the second
indicator is represented in a fixed manner on the display means,
while the first indicator is represented movably in relation to the
second indicator.
4. The flight instrument according to claim 1, wherein the flight
instrument includes a transition zone located between the first
indicator and the second indicator, with the computation means
determining a difference between the first current value and the
variable setpoint for the rotational speed of the main rotor, with
the transition zone representing the difference.
5. The flight instrument according to claim 4, wherein the
transition zone has a specific color depending on an amplitude of
the difference and/or depending on a transitory period during which
the difference is greater than a threshold value of the difference,
with the transitory period being determined by the computation
means.
6. The flight instrument according to claim 1, wherein the aircraft
includes at least one turboshaft engine and a main power
transmission gearbox; each turboshaft engine including a free
turbine that rotatively drives the main rotor by means of the main
power transmission gearbox; and the flight parameters including a
second current value of the rotational speed of the free turbine of
each turboshaft engine, the flight instrument displaying second
information about the rotational speed of the free turbine of each
turboshaft engine, and including at least one fifth indicator of
the second current value of the rotational speed of the free
turbine of each turboshaft engine.
7. (canceled)
8. The flight instrument according to claim 1, wherein the first
indicator is located at a center of the display means.
9. The flight instrument according to claim 1, wherein the display
means are circular in shape.
10. A rotary-wing aircraft including a main rotor, at least one
turboshaft engine, a main power transmission gearbox, and at least
one flight instrument, with each turboshaft engine including a free
turbine that rotatively drives the main rotor by means of the main
power transmission gearbox, wherein the flight instrument is
according to claim 1.
11. A flight instrument procedure that displays first pieces of
information about a rotational speed of a main rotor of a
rotary-wing aircraft equipped with at least one main rotor and at
least one motor, during which procedure: atmospheric parameters and
flight parameters of the aircraft are determined, including a first
current value of the rotational speed of the main rotor; a variable
setpoint is calculated for the rotational speed of the main rotor,
along with at least one lower limit and at least one upper limit of
the rotational speed of the main rotor; the variable setpoint for
the rotational speed of the main rotor is displayed via display
means; the first current value of the rotational speed of the main
rotor is displayed on the display means, with one of the variable
setpoint for the rotational speed of the main rotor and the first
current value of the rotational speed of the main rotor being
represented in a fixed manner on the display means and the other
one of the variable setpoint for the rotational speed of the main
rotor and the first current value of the rotational speed of the
main rotor being represented in a movable manner on the display
means; and the at least one lower limit and at least one upper
limit of the rotational speed of the main rotor are displayed
movably on the display means.
12. The flight instrument procedure according to claim 11, wherein
the variable setpoint for the rotational speed of the main rotor is
represented in a fixed manner on the display means, and the first
current value of the rotational speed of the main rotor is
represented in a movable manner on the display means.
13. The flight instrument procedure according to claim 11, wherein
the first current value of the rotational speed of the main rotor
is represented in a fixed manner on the display means, and the
variable setpoint for the rotational speed of the main rotor is
represented in a movable manner on the display means.
14. The flight instrument procedure according to claim 11, wherein
a difference is determined between the first current value and the
variable setpoint for the rotational speed of the main rotor, and
the difference is displayed on the display means.
15. The flight instrument procedure according to claim 14, wherein
a transitory period is determined during which the difference is
greater than a threshold value of the difference between the first
current value and the variable setpoint for the rotational speed of
the main rotor, and the difference is displayed using a color that
depends on the amplitude of the difference and/or depending on the
transitory period.
16. The flight instrument procedure according to claim 11, wherein
with the aircraft including at least one main rotor, at least one
turboshaft engine, and one main power transmission gearbox, with
each turboshaft engine including a free turbine that rotatively
drives the main rotor by means of the main power transmission
gearbox, at least one second current value of the rotational speed
of the free turbine of each turboshaft engine is displayed.
17. A flight instrument for a rotary-wing aircraft having a main
rotor, the flight instrument comprising: a display having a first
indicator of a current value of a variable setpoint for a
rotational speed of the main rotor and a second indicator of a
current value of the rotational speed of the main rotor; and
wherein one of the indicators is a fixed indicator that is fixed on
the display and the other one of the indicators is a movable
indicator that is movable on the display relative to the fixed
indicator in correspondence with variation of the current value of
the movable indicator and the current value of the fixed indicator
relative to one another.
18. The flight instrument of claim 17 wherein: the first indicator
is the fixed indicator and is fixed on the display regardless of
variation of the current value of the variable setpoint, and the
second indicator is the movable indicator.
19. The flight instrument of claim 17 wherein: the first indicator
is the movable indicator, and the second indicator is the fixed
indicator and is fixed on the display regardless of variation of
the current value of the rotational speed of the main rotor.
20. The flight instrument of claim 17 wherein: the display further
includes a third indicator of a lower limit of the rotational speed
of the main rotor and a fourth indicator of an upper limit of the
rotational speed of the main rotor, and the third and fourth
indicators are movable on the display.
Description
BACKGROUND OF THE INVENTION
[0001] (1) Field of the Invention
[0002] The present invention lies in the area of aircraft flight
instruments. More specifically, the invention relates to a flight
instrument that displays a variable rotational speed of a main
rotor of a rotary-wing aircraft, and also relates to a flight
instrument procedure for displaying such a speed.
[0003] (2) Description of Related Art
[0004] A rotary-wing aircraft usually includes at least one main
rotor that is rotatively driven by a power plant on board the
aircraft. Thus, the main rotor supports the aircraft and provides
its propulsion. Such an aircraft may also include an anti-torque
rear rotor, or, for example, one or two propellers.
[0005] In particular, such a rotary-wing aircraft is piloted
through the monitoring of numerous instruments that represent the
operation of the power plant and of the aircraft. In fact, numerous
mechanical, physical, and aerodynamic limitations must be taken
into consideration by the pilot while the aircraft is being
flown.
[0006] In particular, one instrument indicates, in real time, the
rotational speed of the main rotor of the aircraft. This rotational
speed of the main rotor of the aircraft is often designated by the
abbreviation "NR".
[0007] In particular, the main rotor provides the lift that is
necessary in order to support the aircraft. This lift provided by
the main rotor is directly linked to the rotational speed of this
main rotor. Therefore, control of this rotational speed of the main
rotor of the aircraft is essential in order to ensure this lift
and, consequently, to ensure the flight of the aircraft.
[0008] In contemporary aircraft, the rotational speed of the main
rotor is often essentially constant. However, this rotational speed
may vary over a limited range above and below a constant value that
constitutes a fixed setpoint for the rotational speed of the main
rotor. This rotational speed may vary depending on flight
conditions, such as the altitude of the aircraft or even the path
followed by the aircraft.
[0009] For example, this limited range may represent up to 7% of
this fixed setpoint, with the speeds that constitute variations of
this rotational speed of the main rotor (that is, the acceleration
or the deceleration of the main rotor in rotation) being on the
order of 1% of this fixed setpoint per second. The term "range" is
understood as referring to an interval of values that may be taken
on by the rotational speed of the main rotor of the aircraft.
[0010] For example, for a rotational speed of the main rotor on the
order of 300 revolutions per minute (300 rpm), the variation speed
of this rotational speed is on the order of 3 revolutions per
second (3 rpm/sec).
[0011] Thus, for this type of aircraft and in certain phases of
flight, the control of this rotational speed of the main rotor is
based on sound. In fact, the pilot typically knows, through
habituation, the sound emitted by the main rotor when it is
rotating at the fixed setpoint. Indeed, thanks to his experience,
the pilot is capable of confirming by ear that this rotational
speed of the main rotor is in fact constant and essentially
compliant with the fixed setpoint.
[0012] The instrument that indicates this rotational speed of the
main rotor makes it possible to control the value of this
rotational speed of the main rotor of the aircraft, and is used
essentially by the pilot during flight phases for which this
rotational speed of the main rotor varies.
[0013] This instrument is also used during specific flight phases,
such as during flight under autorotation or in the event of an
engine failure during stationary flight.
[0014] In most aircraft this instrument is an analog instrument,
and is graduated in terms of percentages of the fixed setpoint for
the rotational speed of the main rotor, with this fixed setpoint
corresponding to a graduation mark of "100%". This instrument also
includes indications that correspond to fixed rotational speed
limits that must not be exceeded. In fact, if these fixed limits
are exceeded, damaging effects on the mechanical power-transmission
train may occur, or a risk of engine flameout may arise, for
example, due to excessively sudden deceleration.
[0015] In certain aircraft, this instrument may also indicate the
rotational speed of the free turbine of each turboshaft engine that
drives the main rotor. In fact, by means of their free turbine,
these turboshaft engines drive the main power transmission gearbox,
and, consequently, the main rotor. Indeed, there is a constant
ratio of proportionality between the rotational speed of each free
turbine and the rotational speed of the main rotor.
[0016] In recently manufactured aircraft this instrument has been
replaced by a digital display that indicates, in numerals, the
percentage of the fixed setpoint that constitutes the current value
of the rotational speed of the main rotor. An analog instrument may
still be present; however, in such a case it constitutes a back-up
instrument in the event of a failure of the digital display.
[0017] Nevertheless, the rotational speed of the main rotor of a
rotary-wing aircraft can be caused to vary voluntarily and
continuously over an expanded range that may represent, for
example, as much as 15 or 20% of an average rotational speed of
this main rotor. Therefore, the setpoint that this rotational speed
of the main rotor must maintain is no longer fixed, but instead is
variable, and may change continuously within this expanded range
during the flight of the aircraft.
[0018] Such variations in the rotational speed of the main rotor,
which may occur with major speed variations, make it possible to
obtain several improvements in the operation of the aircraft,
including, in particular, a reduction in the noise generated by the
main rotor, as well as an increase in the maneuverability of the
aircraft and in its performance.
[0019] In the specific case of a hybrid aircraft that flies with a
high forward speed, the rotational speed of the main rotor must be
reduced in order to prevent excessive speed in relation to the air
at the end of each blade of this main rotor and, in particular, to
prevent the said speed from exceeding the speed of sound.
[0020] For example, the variation speed of the rotational speed of
the main rotor is on the order of 5% of this rotational speed of
the main rotor per second.
[0021] Conversely, because the setpoint for the rotational speed of
the main rotor is variable, the rotational speed of the main rotor
may be equal to each value within the expanded range, depending on
the flight conditions.
[0022] Indeed, the pilot of the aircraft must make sure that this
rotational speed of the main rotor always remains essentially equal
to the variable setpoint--a task that requires his attention even
when the flight status is normal.
[0023] Furthermore, the instrument that currently indicates this
rotational speed of the main rotor does not provide effective
assistance to the pilot, because the variable setpoint does not
appear on this instrument. Obviously, this variable setpoint could
be added to this instrument. However, because the setpoint can vary
continuously, such an instrument would make heavy demands on the
attention of the pilot of the aircraft in order to identify the
variable setpoint for the current rotational speed of the main
rotor.
[0024] Furthermore, because this rotational speed of the main rotor
varies continuously, the sound emitted by the main rotor changes
routinely during the course of the flight. Similarly, even if the
pilot continues to monitor the rotational speed of the main rotor
by ear, the pilot can no longer maintain accurate and effective
sound-based control of this rotational speed of the main rotor
(that is, control based on the frequency of the sound emitted by
the rotor). Thus, the pilot requires an instrument that accurately
indicates this rotational speed of the main rotor of the
aircraft.
[0025] Consequently, the use of a variable setpoint for the
rotational speed of the main rotor of an aircraft requires the use
of an instrument that indicates to the pilot, in a clear and simple
manner, both the variable setpoint and the current rotational speed
of the main rotor. Furthermore, the use and the broader
dissemination, in the near future, of such a variable setpoint may
be confusing or disconcerting to pilots of rotary-wing aircraft,
because it calls into question certain customary practices for
flying such an aircraft in relation to its traditional use.
[0026] Thus, the presence of such an instrument should be included
among the key stages of the acceptance of this variable setpoint by
the pilots. Conversely, the use of inappropriate instruments may
limit the range covered by the rotational speed of the main rotor
and/or its dynamic operation, thereby limiting the improvements
contributed by the use of this variable setpoint in terms of the
operation of the aircraft per se.
[0027] Document FR2756256 is known, which describes a power-margin
indicator for a rotary-wing aircraft. This indicator shows the
current value of the collective pitch of the blades of the main
rotor of the aircraft, as well as an available power margin that is
represented in terms of a collective pitch margin. This power
margin is calculated in terms of the technical limitations of the
motors and of the main power transmission gearbox of this
aircraft.
[0028] Furthermore, document WO97/42466 describes a variable
parameter display whose background changes depending on the
operating mode and/or the circumstances. The graduation marks are
fixed, but the display of these graduations, as well as the color
of the marks, may vary, particularly as a function of the
circumstances. The parameter that is displayed may consist, for
example, of the rotational speed of the main rotor of a rotary-wing
aircraft.
[0029] Meanwhile, document EP2402716 describes a system that is
capable of drawing the attention of the pilot of an aircraft to a
particular indicator. For this purpose, the system may zoom in on a
specific portion of this indicator, for example, when this
indicator approaches a setpoint value or a limit value.
[0030] Document WO2006/081334 is also known, which describes a
power indicator for a rotary-wing aircraft. In particular, this
power indicator may provide information about the rotational speed
of the main rotor of this aircraft. It displays, in columns on a
graph, the setpoint for this rotational speed of the main rotor;
the current value of this rotational speed of the main rotor; and
minimum and maximum values for this rotational speed of the main
rotor.
[0031] Moreover, document FR2943131 describes a flight indicator
that shows, on a graduated moving scale, information about the
current collective pitches, the limit values, and the target values
for the main-rotor blades.
[0032] Last, document FR2946322 describes a flight instrument for a
hybrid helicopter that makes it possible to display a maximum
average pitch that is applicable to the propellers of this hybrid
helicopter.
BRIEF SUMMARY OF THE INVENTION
[0033] Thus, the purpose of the present invention is to propose a
flight instrument and a procedure that make it possible to meet the
needs of the pilots of rotary-wing aircraft in terms of managing
the variable setpoint for the rotational speed of the main
rotor.
[0034] One goal of the present invention relates to a flight
instrument that makes it possible to determine flight information
and to ensure the visual conveyance of this information to the
pilots of rotary-wing aircraft. More specifically, one of the goals
of the present invention involves the task of displaying
information about the rotational speed of the main rotor of a
rotary-wing aircraft.
[0035] According to the invention, a flight instrument is intended
for a rotary-wing aircraft. Such an aircraft is usually equipped
with at least one main rotor; at least one motor, such as a
turboshaft engine; and at least one set of means for determining
atmospheric parameters and the flight parameters of the aircraft,
including a first current value of a rotational speed of the main
rotor. The flight instrument displays first pieces of information
about this rotational speed of the main rotor, and includes:
[0036] display means,
[0037] at least one set of computation means enabling the
determination of a setpoint for the rotational speed of the main
rotor, along with a lower limit and at least one upper limit of the
rotational speed of the main rotor,
[0038] a first indicator of the setpoint for this rotational speed
of the main rotor,
[0039] a second indicator of the first current value of this
rotational speed of the main rotor, and
[0040] a third indicator and a fourth indicator, corresponding
respectively to at least one lower limit and at least one upper
limit of this rotational speed of the said main rotor.
[0041] The term "current value" of a parameter is understood as
referring to the value of this parameter in real time.
[0042] The aircraft includes at least one set of means for
determining atmospheric parameters and the flight parameters of the
aircraft that are useful, in particular, in terms of the operation
and piloting of this aircraft. These atmospheric parameters
include, for example, the atmospheric pressure and the temperature
outside the aircraft, and the flight parameters may consist of the
forward speed of the aircraft, its altitude, the rotational speed
of the main rotor, or even the operating parameters of each
motor.
[0043] This flight instrument according to the invention may be
located on the instrument panel of the aircraft, in order to
indicate these first pieces of information about the rotational
speed of the main rotor to the pilot.
[0044] This flight instrument is notable in that either the first
indicator or the second indicator is represented in a fixed manner
on the display means, while the other indicator is represented
movably, with the third and fourth indicators being represented
movably.
[0045] The first indicator is preferably represented in a fixed
manner on the display means, regardless of the value of this
setpoint. The value of the setpoint may be a constant, or else may
be variable. In fact, the setpoint for this rotational speed of the
main rotor, which is traditionally fixed, may be variable,
particularly in order to improve the performance of the aircraft
and to reduce these noise nuisances. This setpoint for the
rotational speed of the main rotor may vary, in particular,
depending on atmospheric parameters and on the flight parameters of
the aircraft, such as, for example, the forward speed of the
aircraft and/or its flight phase.
[0046] The second indicator is then represented movably and is
shifted as a function of the first current value of this rotational
speed of the main rotor, as shown on the display means, in relation
to the first indicator.
[0047] Accordingly, this flight instrument makes it possible to
indicate, clearly and continuously, the difference between the
setpoint and the first current value of this rotational speed of
the main rotor, with this difference being represented by the space
between the first indicator and the second indicator. Indeed, when
the first current value is equal to the setpoint, the first and
second indicators coincide.
[0048] The first indicator is preferably centered on the display
means, with the shape of these display means being, for example,
circular. The first indicator and the second indicator may take the
shape of a needle that passes through the center of the circular
shape of these display means. In such a case, the second indicator
moves rotatively about this center.
[0049] These display means may also take the shape of a scrolling
or drop-down column, or of a moving band or ribbon, with the first
indicator being located at the center of the scrolling or drop-down
column, or of the moving band or ribbon, and with the second
indicator shifting its position in a rectilinear manner.
[0050] Furthermore, this rotational speed of the main rotor
includes at least one lower limit and at least one upper limit,
which are represented respectively by the third and fourth
indicators.
[0051] The lower and upper limits may be fixed, while the value of
the setpoint is a variable value. In such a case, the third
indicator and the fourth indicator are shifted on the display means
in relation to the first indicator as soon as the setpoint
varies.
[0052] Nevertheless, each lower and upper limit may also be
variable, regardless of whether the value of the setpoint is a
constant value or a variable value. The third indicator and the
fourth indicator may then be shifted on the display means in
relation to the first indicator when the values of each lower
and/or upper limit vary, as well as when the value of the setpoint
varies.
[0053] These lower and upper limits are, for example, variable
following the failure of a motor, in the case of a twin-engine
aircraft, particularly with the lower limit being capable of being
increased in order to approach an optimal rotational speed of the
main rotor.
[0054] Similarly, among other things, the upper limit makes it
possible to prevent excessive speed in relation to the air at the
end of each blade of this main rotor and, in particular, to prevent
the said speed from exceeding the speed of sound. Now, the speed of
sound may vary substantially depending on atmospheric conditions,
and particularly depending on the temperature. Indeed, this upper
limit may vary depending on atmospheric conditions--for example,
when the temperature outside the aircraft varies.
[0055] The third and fourth indicators may take the shape of
markings on the display means. For example, when the shape of the
display means is circular, the third and fourth indicators take the
shape of markings consisting of arcs of a circle. Similarly, when
the display means take the shape of a scrolling or drop-down
column, or of a moving band or ribbon, the third and fourth
indicators take the shape of linear markings.
[0056] Furthermore, each lower or upper limit may include multiple
zones: for example, at least one first zone to be avoided and at
least one prohibited second zone.
[0057] Advantageously, this flight instrument according to the
invention makes it possible to limit the amount of information
provided to the pilot of the aircraft. In fact, even though the
setpoint is variable, it appears in a fixed manner in the form of
the first indicator on the display means of this flight instrument.
Subsequently, the pilot is not distracted by this variable
setpoint, and can concentrate on the difference between the first
current value and the setpoint.
[0058] Moreover, these lower and upper limits are displayed on the
display means in the form of the third and fourth indicators,
depending on the value of the setpoint. Thus, on this flight
instrument, the pilot of the aircraft can continuously see these
lower and upper limits in relation to the setpoint and in relation
to the first current value of this rotational speed of the main
rotor. Accordingly, this flight instrument makes it possible
effectively to recover from the approach to either of these limits
by the setpoint and/or by the first current value of this
rotational speed of the main rotor.
[0059] Conversely, unlike the instruments traditionally used in
aircraft, the display means of the flight instrument according to
the invention do not include graduation marks. Indeed, the pilot
does not know the exact first current value of this rotational
speed of the main rotor based on the second indicator. Instead, the
pilot knows only the position of this value in relation to the
setpoint and in relation to the lower and upper limits.
[0060] Nevertheless, the flight instrument according to the
invention may include a digital indication, in order to display
with exactitude this first value of the rotational speed of the
main rotor.
[0061] For example, the flight instrument according to the
invention displays this first current value of the rotational speed
of the main rotor as a percentage of an average value of this
rotational speed over the expanded range of variation of this
rotational speed.
[0062] Nevertheless, the main rotor of an aircraft may include a
particular operational point, to which a particular value of the
rotational speed of the main rotor corresponds. Conversely, this
particular value of the rotational speed of the main rotor is not
always located at the center of the expanded range of variation of
this rotational speed. In such a case, the flight instrument
according to the invention preferably displays this first current
value of the rotational speed of the main rotor as a percentage of
this particular value of the rotational speed of the main
rotor.
[0063] Furthermore, each lower or upper limit may include multiple
zones: for example, two first zones to be avoided and two
prohibited second zones. In the prohibited zone corresponding to
the upper limit, the rotational speed may be too high, thereby
posing the risk of damaging the turboshaft engines and/or the main
power transmission gearbox. Conversely, in the prohibited zone
corresponding to the lower limit, the rotational speed may be
insufficient to ensure, for example, the safety of the aircraft.
The zones to be avoided may consist, for example, of safety margins
pertaining to the prohibited zones.
[0064] Nevertheless, as mentioned earlier, the use of such a
variable setpoint for the rotational speed of the main rotor may be
confusing or disconcerting to pilots of rotary-wing aircraft,
because it calls into question certain customary flight practices
relating to the traditional use of such an aircraft. Furthermore,
this rotational speed of the main rotor is often monitored by ear,
with the pilot knowing, through habituation, the sound emitted by
the main rotor when it is rotating at a fixed setpoint.
[0065] Because this rotational speed may be variable, this
sound-based control of the rotational speed of the main rotor is no
longer either effective or reliable. Therefore, the pilot must
routinely use an instrument that indicates, in particular, this
rotational speed of the main rotor and its setpoint.
[0066] Advantageously, the flight instrument according to the
invention enables a clear display of the variable setpoint and of
the first current value of this rotational speed of the main rotor.
In fact, because the first indicator represents the variable
setpoint in a fixed manner, the pilot's attention is not
monopolized by this variable setpoint, and the pilot can focus part
of his attention primarily on the difference between the setpoint
for the rotational speed of the main rotor and the first current
value of this rotational speed.
[0067] Indeed, this flight instrument makes it possible to limit
the density of the information provided to the pilot, which
information density is already substantial on board the latest
generation of rotary-wing aircraft. Furthermore, when the first
current value of this rotational speed of the main rotor is equal
to the setpoint, the first and second indicators coincide, with
this flight instrument thus reproducing a pattern that is well
known to aircraft pilots.
[0068] Moreover, in order to facilitate the pilot's awareness of
this difference between the first current value of this rotational
speed of the main rotor and the setpoint, the flight instrument
according to the invention includes a transition zone that consists
of filling, with a specific color, the space separating the first
indicator and the second indicator, with the transition zone
representing this difference. The flight instrument according to
the invention uses calculation means that it includes in order to
determine the amplitude of this difference and to display the
corresponding transition zone with the specific color.
[0069] By showing the difference between the first current value of
this rotational speed of the main rotor and the setpoint, this
transition zone makes it possible to attract the pilot's attention.
Therefore, the pilot does not in fact need to continuously observe
the flight instrument according to the invention. The pilot should
use this flight instrument above all when a difference exists
between the first current value of this rotational speed of the
main rotor and the setpoint--that is, when the transition zone is
visible. In particular, this makes it possible to limit the density
of the information provided to the pilot of the aircraft.
[0070] Advantageously, this transition zone may be shown in
different colors, depending on the amplitude of this difference
between the first current value of this rotational speed of the
main rotor and its setpoint, and also depending on a transitory
period that is used to cause the first current value to move toward
the setpoint. The transitory period may, for example, consist of
the period during which the amplitude of this difference is greater
than a given difference threshold, with the transitory period being
determined by the computation means and with the difference
threshold being predetermined.
[0071] For example, the color of the transition zone may be green
when the amplitude of the difference between the first current
value of this rotational speed of the main rotor and the setpoint
is less than 1% of the setpoint value. The color of this transition
zone is orange when the amplitude of this difference is between 1
and 3% of the setpoint value, and red when the amplitude of this
difference is greater than 3% of the setpoint value,
[0072] Moreover, the amplitude of this difference and the
transitory period do not have the same effects on the color of the
transition zone depending on whether the setpoint is or is not in
the process of varying.
[0073] For example, when the setpoint varies, this difference may
be substantial, and should be rapidly reduced so that the first
current value of the rotational speed of the main rotor approaches
its setpoint. In such a case, the color of the transition zone may,
for example, be orange, to indicate to the user that he must act on
the first current value of the rotational speed of the main
rotor.
[0074] If this difference does not diminish during the transitory
period while the setpoint no longer varies, the color of the
transition zone may turn red, to draw the user's attention to this
difference. For example, the duration of this transitory period may
be on the order of several seconds.
[0075] Conversely, if this difference diminishes rapidly, with the
first current value becoming very close to the setpoint, then the
color of this transition zone may turn green, indicating to the
user that he has maneuvered properly and at the correct speed, in
order to rapidly reach the setpoint.
[0076] The computation means of the flight instrument according to
the invention make it possible to determine the color of the
transition zone in accordance with one or more predefined
algorithms. These algorithms use, for example, the amplitude of the
difference between the first current value and the setpoint, as
well as the transitory period and the difference threshold.
[0077] Similarly, the third and fourth indicators may be of
different colors, in order to alert the pilot when the first
current value of this rotational speed of the main rotor approaches
its lower limit or its upper limit.
[0078] The present invention also relates to a rotary-wing aircraft
that includes at least one main rotor, at least one turboshaft
engine, a main power transmission gearbox, at least one set of
means for determining atmospheric parameters and the flight
parameters of the aircraft, and an instrument panel equipped with
various instruments, including at least one flight instrument as
described hereinabove. Each turboshaft engine includes a free
turbine that rotatively drives the main rotor, doing so by means of
the main power transmission gearbox.
[0079] Furthermore, the flight instrument of this aircraft may also
include at least one fifth indicator of a second current value of
the rotational speed of the free turbine of each turboshaft
engine.
[0080] In fact, each free turbine drives the main rotor, doing so
by means of the main power transmission gearbox. Indeed, there is
an essentially constant ratio of proportionality between the
rotational speed of the free turbine and the rotational speed of
the main rotor. Consequently, it is possible to indicate, on the
flight instrument of the aircraft, a second current value of the
rotational speed of the free turbine of each turboshaft engine,
doing so by means of the fifth indicator. This fifth indicator is
oriented in parallel with the second indicator. The first indicator
then corresponds, on the one hand, to a setpoint for the rotational
speed of the main rotor and, on the other hand, to a setpoint for
the rotational speed of the free turbine.
[0081] Furthermore, supplemental sixth and seventh indicators may
be added to the flight instrument according to the invention in
order to represent the lower and upper limits of this rotational
speed of the free turbine of each turboshaft engine.
[0082] When this aircraft has a single turboshaft engine, the
flight instrument includes a fifth indicator of a second current
value of the rotational speed of the free turbine of this
turboshaft engine. Conversely, when this aircraft has two
turboshaft engines, the flight instrument includes two fifth
indicators, with each fifth indicator representing the second
current value of the rotational speed of the free turbine of each
corresponding turboshaft engine.
[0083] Furthermore, the display logic of the flight instrument
according to the invention may be reversed, particularly in
accordance with the pilot's requirements.
[0084] In such a case, the second indicator is represented in a
fixed manner on the display means, with the first indicator being
represented movably in relation to the second indicator. The third
and fourth indicators are represented movably on the display
means.
[0085] Accordingly, the current value of the rotational speed of
the main rotor is represented in a fixed manner. In such a case,
the setpoint is represented movably on the flight instrument, in
the same way as the lower and upper limits of the rotational speed
of the main rotor.
[0086] The present invention also relates to a flight instrument
procedure for a rotary-wing aircraft. Such a flight instrument
procedure displays first pieces of information about the rotational
speed of a main rotor of a rotary-wing aircraft. During this flight
instrument procedure:
[0087] Atmospheric parameters and the flight parameters of the
aircraft are determined, including the first current value of a
rotational speed of its main rotor,
[0088] A setpoint is calculated for the rotational speed of the
main rotor, along with at least one lower limit and at least one
upper limit of the rotational speed of the main rotor,
[0089] The setpoint for the rotational speed of the main rotor is
displayed on display means,
[0090] The first current value of the rotational speed of the main
rotor is displayed on the display means, and
[0091] At least one lower limit and at least one upper limit of
this rotational speed of the main rotor are displayed movably on
the display means.
[0092] The setpoint for the rotational speed of the main rotor is
preferably represented in a fixed manner on the display means, and
the first current value of the rotational speed of the main rotor
is preferably represented movably.
[0093] Nevertheless, the first current value of the rotational
speed of the main rotor may also be represented in a fixed manner
on the display means, and the setpoint for the rotational speed of
the main rotor may be represented movably.
[0094] Furthermore, during this flight instrument procedure, a
difference may be determined between the first current value of the
rotational speed of the main rotor and its setpoint, and this
difference may be displayed on the display means in the form of a
transition zone.
[0095] A transitory period may also be determined during which this
difference is greater than a difference threshold between the first
current value of the rotational speed of the main rotor and its
setpoint, with this difference then being displayed using a
specific color, depending on the amplitude of this difference
and/or depending on the transitory period.
[0096] Moreover, an aircraft generally includes at least one main
rotor, at least one turboshaft engine, and a main power
transmission gearbox, with each turboshaft engine including a free
turbine that rotatively drives the main rotor, doing so by means of
the main power transmission gearbox.
[0097] A second current value of the rotational speed of the free
turbine of each turboshaft engine may also be displayed on the
display means, in which case the setpoint for this rotational speed
of the free turbine of each turboshaft engine coincides with the
setpoint for the rotational speed of the main rotor on the display
means.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0098] The invention and its advantages will become clear in
greater detail within the scope of the following description, which
includes examples of embodiments provided for illustrative
purposes, with reference to the attached figures, among which:
[0099] FIG. 1 shows a rotary-wing aircraft that includes at least
one flight instrument according to the invention,
[0100] FIG. 2 shows a flight instrument traditionally used in an
aircraft, and
[0101] FIGS. 3 and 4 show an embodiment of the flight instrument
according to the invention.
[0102] Elements that appear in two or more different figures are
indicated by the same reference number.
DETAILED DESCRIPTION OF THE INVENTION
[0103] According to FIG. 1, a rotary-wing aircraft 15 includes a
main rotor 16, a rear rotor 14, a turboshaft engine 17, and a main
power transmission gearbox 19. The turboshaft engine 17 includes a
free turbine 18 that rotatively drives the main rotor 16, as well
as the rear rotor 14, doing so by means of the main power
transmission gearbox 19. Furthermore, the aircraft 15 includes
means 13 for determining atmospheric parameters and the flight
parameters of the aircraft 15 that are useful in terms of the
operation and piloting of this aircraft 15.
[0104] The aircraft 15 also includes an instrument panel 11
equipped with various instruments, including a flight instrument 10
that displays first pieces of information about the rotational
speed of the main rotor 16 and second pieces of information about
the rotational speed of the free turbine 18 of the turboshaft
engine 17. This flight instrument 10 also includes computation
means 12, and is shown in FIGS. 3 and 4.
[0105] FIG. 2 shows a flight instrument 20 that is traditionally
used in a rotary-wing aircraft to inform the pilot by displaying
the rotational speed of the main rotor and the rotational speed of
the free turbine of two turboshaft engines. This flight instrument
20 includes circular display means 21 equipped with graduation
marks 22 and colored zones 24,25 consisting of arcs of a circle, as
well as a needle 23 indicating a first current value of the
rotational speed of the main rotor and two markers 27,27'
indicating a second current value of the rotational speed of the
free turbine of each turboshaft engine.
[0106] The graduation marks 22 correspond to two percent of the
rotational speeds, with the "100%" mark corresponding, on the one
hand, to a fixed setpoint for the rotational speed of the main
rotor and, on the other hand, to a setpoint for the rotational
speed of the free turbine of the two turboshaft engines.
[0107] The colored zones 24,25 correspond respectively to ranges
for the use of the main rotor and of the free turbine of the two
turboshaft engines. The central zones 24a,25a correspond to normal
operating ranges, and may, for example, be green. The zones 24b,25b
correspond to limit operating ranges, which are possible but which
should be avoided, and whose color may be orange.
[0108] Accordingly, the needle 23 and the two markers 27,27'
continuously indicate, respectively and in real time, the
percentage of the current values of the rotational speeds of a main
rotor and of the free turbine of each turboshaft engine in relation
to the corresponding setpoints.
[0109] Furthermore, a digital indicator 28 also indicates the value
of this percentage of the rotational speed of the main rotor in
relation to the corresponding setpoint. This flight instrument 20
is perfectly suitable when these setpoints for rotational speeds
are constant, which is the case with most of the aircraft that are
currently in use.
[0110] Nevertheless, it is worthwhile for the setpoint for the
rotational speed of a main rotor of an aircraft to be variable
within an expanded range consisting, for example, of 15 to 20%, in
order, on the one hand, to improve the maneuverability in the
performance of the aircraft and, on the other hand, to reduce its
noise nuisances. In such a case, the flight instrument 20 is not
suitable, because it cannot tell the pilot about these variables
setpoints. It may be possible to add one or more supplemental
indicators corresponding to each setpoint, but in such a case this
flight instrument 20 would become difficult to use by a pilot who
must simultaneously monitor the change in the setpoints and the
change in the rotational speeds, in addition to the multitude of
other information that must also be monitored during a flight.
[0111] The flight instrument 10 shown in FIGS. 3 and 4 makes it
possible to display clearly such a variable setpoint for the
rotational speed of the main rotor 16 of an aircraft 15, as well as
the rotational speed of the main rotor 16, the rotational speed of
the free turbine 18 of the turboshaft engine 17, and the lower and
upper limits of these rotational speeds.
[0112] The flight instrument 10 includes semi-circular display
means 1 and several indicators 2,3,4,5,7,34,35. The center 9 of the
circle forming the outline of these semi-circular display means 1
is shown in FIGS. 3 and 4.
[0113] The first indicator 2 is shown in a fixed manner on display
means 1, and corresponds to the variable setpoint for the
rotational speed of the main rotor 16. This first indicator 2 is a
needle that is oriented vertically in the middle of the display
means 1, passing through the center 9.
[0114] The second indicator 3 corresponds to the first current
value of the rotational speed of the main rotor 16. This current
value of the rotational speed of the main rotor 16 may vary,
depending on the duration of its presence. Indeed, this second
indicator 3 is movable on the display means 1. This second
indicator 3 is a needle that is located at the center 9 of the
semi-circular display means 1 and that can rotate about this center
9.
[0115] The third and fourth indicators 4,5 correspond to the lower
and upper limits of the rotational speed of the main rotor 16.
These lower and upper limits may be fixed or variable.
Consequently, these third and fourth indicators 4,5 are movable on
the display means 1. These third and fourth indicators 4,5 consist
of markings in the form of arcs of a circle that are located on the
periphery of the display means 1. These arcs of a circle are
centered on the center 9 and can rotate about the center 9.
[0116] Furthermore, the third and fourth indicators 4,5 include
multiple zones, consisting of two first zones to be avoided 4a,5a
and two prohibited second zones 4b,5b. In the second prohibited
zone 5b, which corresponds to the upper limit, the rotational speed
of the main rotor 16 may be too high, thereby posing the risk of
damaging the turboshaft engine 17 and/or the main power
transmission gearbox 19. Conversely, in the prohibited zone 4b,
which corresponds to the lower limit, this rotational speed may be
insufficient to ensure, for example, the safety of the aircraft 15.
The zones to be avoided 4a,5a may consist, for example, of safety
margins pertaining to the prohibited zones 4b,5b.
[0117] A fifth indicator 7 corresponds to the second current value
of the rotational speed of the free turbine 18, and is movable on
the display means 1. This fifth indicator 7 is a marker that is
located at the periphery of the display means 1, outside the third
and fourth indicators 4,5, and can rotate about the center 9.
[0118] The sixth and seventh indicators 34,35 correspond to the
lower and upper limits of the rotational speed of the free turbine
18, which limits may be fixed or variable. Consequently, these
sixth and seventh indicators 34,35 are movable on the display means
1. Like the fourth and fifth indicators 4,5, these sixth and
seventh indicators 34,35 consist of markings in the form of arcs of
a circle that are located on the periphery of the display means 1,
centered on the center 9, and capable of rotating about this center
9.
[0119] The flight instrument 10 also includes a transition zone 6
that is located between the first indicator 2 and the second
indicator 3. This transition zone 6 corresponds to the difference
between the first current value of the rotational speed of the main
rotor 16 and its setpoint. The computation means 12 make it
possible, in particular, to determine the amplitude of this
difference and to display the corresponding transition zone 6 using
a specific color.
[0120] Last, the flight instrument 10 includes a digital indicator
8 that displays the first current value of the rotational speed of
the main rotor 16, which first current value is a percentage of a
specific value of this rotational speed of the main rotor 16. This
specific value of the rotational speed of the main rotor 16
actually corresponds to a particular operational point of the main
rotor 16 of the aircraft 15.
[0121] In FIG. 3, which represents a first example of the display,
the first indicator 2 is near the zone to be avoided 5a of the
upper limit of the rotational speed of the main rotor 16. Moreover,
the digital indicator 8 displays a rotational value corresponding
to 108% of the specific value of the rotational speed of the main
rotor 16. The second indicator 3 is located to the left of the
first indicator 2, signifying that the first current value of the
rotational speed of the main rotor 16 of the aircraft 15 is lower
than its setpoint.
[0122] Furthermore, the transition zone 6 is relatively large, with
the second indicator 3 being located fairly far from the first
indicator 2. In this first example, the color of this transition
zone 6 may be red, in order to tell the pilot to act so that this
first current value of the rotational speed of the main rotor 16 of
the aircraft 15 can be increased rapidly in order to approach the
setpoint. The flight instrument 10 also indicates that the second
current value of the rotational speed of the free turbine 18 is
lower than its setpoint, with the fifth indicator 7 being to the
left of the first indicator 2.
[0123] Operationally, this first example may correspond to an entry
into a stationary flight phase of the aircraft 15.
[0124] In FIG. 4, which represents a second example of the display,
the first indicator 2 is near the zone to be avoided 4a of the
lower limit of the rotational speed of the main rotor 16. Moreover,
the digital indicator 8 displays a rotational value corresponding
to 92% of the specific value of the rotational speed of the main
rotor 16. The second indicator 3 is located to the right of the
first indicator 2, signifying that the first current value of the
rotational speed of the main rotor 16 of the aircraft 15 is higher
than its setpoint.
[0125] Furthermore, the transition zone 6 is relatively small, with
the second indicator 3 being located near the first indicator 2. In
this second example, the color of this transition zone may be
green, in order to indicate to the pilot that the situation does
not present any risks. However, the pilot may act so that the first
current value of the rotational speed of the main rotor 16 moves
closer to the setpoint. The flight instrument 10 also indicates
that the second current value of the rotational speed of the free
turbine 18 is very slightly higher than its setpoint, with the
fifth indicator 7 being to the right of the first indicator 2.
[0126] Operationally, this second example may correspond to a
descending flight phase of the aircraft 15.
[0127] Naturally, the present invention is subject to numerous
variants in terms of its implementation. Although several
embodiments have been described, it will be readily understood that
not all of the possible modes can be identified exhaustively. Any
of the means described herein may of course be replaced by
equivalent means without departing from the scope of the present
invention.
* * * * *