Warning via weight monitoring in case of a spur roll

Abstract

A skid wheel (20) contains a retaining part (22) for attachment to an aircraft (2), a wheel (24), a sensor (26) for detecting the pressure force (F) exerted on the ground (12) and an evaluation module (28) to determine values ​​(W0-4) of the pressure force (F) and to issue a warning message (32) when two values ​​(W0-4) differ from each other by at least a minimum difference (DMIN). In a method for monitoring an aircraft (2), before the aircraft (2) is taken off, the tailwheel (20) is attached to the aircraft (2) and the evaluation module (28) determines at least one value (W0-4), determines values ​​(W0-4) at subsequent time intervals (I0-4) and checks whether the warning message (32) is to be issued and, if so, issues it.

Description

[0001] The invention relates to a tail roller in relation to a warning to remove it from an aircraft before takeoff.

[0002] DE 20 2021 002 662 U1 discloses a warning device for checking the proper condition of an aircraft before takeoff, in particular the removal of the tail dolly on a glider. It is known that gliders are very often temporarily equipped with a so-called tail dolly for maneuvering on the ground. This allows the aircraft to be easily turned on the main wheel with the tail facing in the correct direction and maneuvered. This tail dolly (also called "the dolly" for short) often weighs between 5 and 15 kg. If it is accidentally left on the tail of the aircraft before takeoff, the aircraft can become aerodynamically unstable due to the overall center of gravity being too far back. In the worst case, it could crash after takeoff.A tail roll warning system that can be retrofitted to any aircraft consists of a transmitter, receiver, sensors and evaluation electronics to detect an aircraft ready for takeoff with the tail roll still in place and to give a clear warning.

[0003] EP 0 850 170 B1 discloses a tail support for protecting against and limiting the shock loads acting on the tail section of an aircraft.

[0004] The object of the present invention is to provide improvements with regard to the warning relating to a tail roller to be removed from an aircraft.

[0005] The object is achieved by a spur roller according to patent claim 1. Preferred or advantageous embodiments of the invention as well as other categories of invention emerge from the further claims, the following description and the attached figures.

[0006] The tail dolly is designed to support and maneuver an aircraft on a surface.

[0007] The tail dolly contains a retaining piece. This can be removably attached to the aircraft. The tail dolly is considered assembled when the retaining piece is actually attached to the aircraft.

[0008] The tail-end dolly contains a wheel. The wheel is attached to the support. During proper operation of the tail-end dolly, the wheel rests on a surface. "Proper" means that such use of the tail-end dolly is to be expected or assumed. The invention is therefore based on the fact that this requirement—in this case, resting on the surface—is actually met. This property is therefore assumed within the scope of the invention.

[0009] The intended use also describes the actual purpose of the tail dolly, namely to make the aircraft rollable on the ground at the point where the tail dolly or its holding part is attached, so that it does not have to be lifted or supported manually, for example, in order to maneuver the aircraft on the ground.

[0010] The tail dolly contains a sensor. The sensor is specifically a force sensor. The sensor is designed to detect a compressive force. The compressive force is the force exerted by the aircraft on the ground via the tail dolly. "Compressive force" is to be understood broadly here and refers either to an actual force or a quantity correlated with it. The sensor can therefore detect the force, weight, force, pressure, etc., with which the aircraft is currently exerting a load on the tail dolly and thus on the ground, as this is reflected in the corresponding compressive force or its value.

[0011] The sensor could, for example, be implemented by compressing a (closed) hydraulic cylinder and using a pressure sensor to measure the pressure in the cylinder. Alternatively, the extension / displacement / length change of a spring could be measured, which is compressed with increasing compressive force, or a bending sensor could be used, which is bent more or less depending on the strength of the compressive force.

[0012] The tail roller contains an evaluation module; this is configured as follows: For at least two consecutive time intervals, the evaluation module records or determines a respective pressure force value. The "time interval" is to be understood in the same broad sense and can also be (in the technical sense) a point in time; the length of the time interval is then zero.

[0013] The value can be a single value (e.g., a discrete measured value / sample) or a value already processed from several individual values ​​within a time interval (average value) or at other time intervals (trend value). In other words, the force (weight / pressure, etc.) with which the aircraft exerts a load on the support part or tail roller / ground is recorded at two different times, time periods, or points in time.

[0014] The evaluation module is also configured to issue a warning message if a value from a later time interval deviates from a value from an earlier time interval by at least a minimum difference. The minimum difference can be positive (force increase) or negative (force reduction). In other words, a warning message is issued if the value and thus the corresponding compressive force, weight, pressure, etc. on the tail roller have changed over time by at least the minimum difference. Otherwise (change below the minimum difference), no warning message is issued.

[0015] The minimum difference must be adapted to the force conditions on a specific aircraft or aircraft type or selected accordingly.

[0016] The difference is directed in a specific direction, so only an increase or decrease in force is valid. The magnitude of the minimum difference is crucial here; the time difference between the two time intervals is less important or irrelevant.

[0017] The invention is based on the idea that the weight, and thus force / pressure ratios, relative to the ground on an aircraft, and thus also the pressure force / weight / load exerted on the tail roller change significantly (by at least the minimum difference) when the aircraft is prepared for takeoff by a pilot boarding the aircraft. This is because the additional weight of the pilot in the aircraft changes these force ratios.

[0018] This triggers the warning message when the pilot boards the aircraft. This alerts the pilot or bystanders to the tail ball attached to the aircraft. The warning message can then be used by the pilot or bystanders to remove the tail ball in time before takeoff, preventing accidents with the aircraft caused by tail balls accidentally attached in flight.

[0019] The basic principle of the present invention is based in particular on the fact that the tail dolly or its sensor evaluates the relationship between a nose mass and a tail mass with respect to a support point and thus a pivot point / axis of the aircraft, in this case the sole main landing gear. The tail dolly supports the aircraft in front of or behind this main landing gear. Depending on how much the relationship between the nose mass and tail mass shifts relative to each other, the warning message is issued or not. The basic principle is symbolically comparable to a scale with a support point on the main landing gear / pivot point. In other words, the sensor measures the relationship between the nose and tail mass.

[0020] The invention offers the advantage that the tail roller is configured to issue the warning message on its own, thus requiring no remote station, as is the case with transmitter / receiver solutions, for example, where a transmitter is attached to the tail roller but requires an external receiver, for example, in the cockpit of a glider. The tail roller according to the invention is thus particularly simple in design.

[0021] According to the invention, a self-warning spur roller is obtained.

[0022] Depending on the intended installation location of the tail roller on the aircraft and its conditions, the minimum difference can cause a relief (reduction in pressure force) or a load (increase in pressure force) to trigger the warning message.

[0023] In a preferred embodiment, the tail dolly is one that is designed to be attached to the tail of the aircraft. Tail dollies are often attached to the tail of gliders. They are particularly difficult for the pilot to detect at the tail, so the warning message is particularly useful here.

[0024] In a preferred embodiment, the tail dolly is one that is intended to be attached to a glider as an aircraft. A glider can also be a so-called "motor glider." In gliders, tail dollies accidentally attached in flight are particularly critical, as they have a comparatively high mass compared to the glider itself and can therefore seriously impair the flight characteristics. A self-warning tail dolly is particularly useful in this case.

[0025] In a preferred embodiment, the minimum difference is a minimum decrease in the value over time. In other words, the warning message is issued when the pressure force has decreased between a first point in time / time interval and a later point in time / time interval. This embodiment is based on the knowledge that, particularly in gliders, a pilot takes seat in front of a contact point of the glider on the ground, namely the main wheel. Due to the leverage effect with regard to the contact point (main wheel), the load on the tail of the aircraft is thus relieved when the pilot climbs in. However, the tail dolly is attached to the tail. Thus, the load on the tail of the aircraft decreases when the pilot climbs in. This decrease in pressure force is monitored by the tail dolly, and if there is a corresponding decrease, the warning message is issued.In this respect, the invention provides a particularly simple indirect monitoring system to determine whether a pilot is boarding the aircraft, in order to issue a warning message. This results in a very reliable warning system for a tail roll.

[0026] In a preferred embodiment, the evaluation module is configured to determine at least one of the values ​​(of a specific time interval) by filtering a compressive force curve recorded - in particular only within this time interval. The compressive force curve can be continuous, but it can also be individual values, e.g. digital sample values ​​of the compressive force, which are recorded one after the other or in chronological order. By filtering, for example, fluctuations / noise / measurement errors, etc. of the compressive force or its temporal curve can be eliminated in order to determine a meaningful value that can then be easily processed further in the spur roller or evaluation module.

[0027] In principle, filtering can also be performed using analog filtering (low-pass). Digital filtering (averaging) is preferred.

[0028] In a preferred variant of this embodiment, the filtering includes averaging. The filtering is performed, in particular, exclusively based on the values ​​of the same time interval for which the value is to be determined. Averaging serves, in particular, to filter out noise or fluctuations from the pressure force curve within the time interval in order to create a meaningful value for the respective time interval. The value is then, in particular, or contains, an average value.

[0029] In a preferred variant of this embodiment, the filtering includes determining a trend value of the pressure force in the time interval relative to a reference time interval. In other words, a trend value is determined for a specific time interval that indicates whether the pressure force value in the time interval in question has tended to decrease or increase relative to a previous, i.e. historical, reference time interval. Based on the trend value, it is particularly easy to decide whether and by what amount the pressure force has changed. This makes it particularly easy to infer the above-mentioned boarding or disembarkation of a pilot. The value is then or contains, in particular, a trend value.

[0030] In general, the value can also be represented as a vector / value tuple of multiple (sub)values. For example, the value for a given interval can contain a mean and a trend value.

[0031] The trend value is calculated based on the mean value of the compressive force over a given time interval. In other words, the trend value describes the change in the mean values ​​of different time intervals.

[0032] In a preferred variant of this embodiment, the evaluation module is configured to only issue the warning message when the trend values ​​averaged over several time intervals deviate from the value of the reference time interval by at least one trend threshold. In other words, the trend must, on average, tend in the required direction over at least two, in particular 3, 4, or 5 time intervals, while exceeding the trend threshold, before the warning message is issued. Thus, fluctuations in the compressive force values ​​can be suppressed to prevent the warning message from being accidentally triggered.

[0033] In particular, the following results:The invention is based on the theory of a load jump (difference in the absorbed loads), but does not detect this jump directly using the difference between two mean values. In particular, a trend is formed: a certain number of values ​​(X, e.g., 8, mean values) / samples (time intervals 1 to 8) are always related to the future (i.e., with advancing time) to a reference mean value (mean value in time interval 0). This trend reference is (after completion of the first trend formation, e.g., over 8 values) shifted to the next mean value (trend of the mean values ​​of time intervals 2 to 9, related to time interval 1), etc. The resulting trend diagram (display: How will the mean change on average in the next X mean values) is then summed (integration of time-discrete signals is the sum of those signals). The sum is then classified (e.g.,“Trend threshold exceeded?”) to assess a warning (i.e., is the warning message issued or not).

[0034] In a preferred embodiment, the evaluation module is configured to output the warning message to the environment of the tail roller, in particular the aircraft. In particular, the warning message is output exclusively to the environment, i.e., not to a remote station of the tail roller, such as a receiver. Thus, a particularly simple warning system for a tail roller can be established, which is implemented solely in the tail roller itself and does not require any external devices, especially remote stations.

[0035] In a preferred embodiment, particularly in combination with the output to the environment, the evaluation module is configured to output the warning message as an audio and / or light signal. In other words, the tail dolly draws attention to itself through light and / or audio signals so that it is not forgotten to be removed from the aircraft before takeoff. Such audio and light signals are particularly easy and intuitive to perceive by anyone, in particular the pilot, but also bystanders or, for example, an air traffic control center, and without any other technical aids, so that the pilot can be effectively warned before takeoff not to forget to remove the tail dolly.

[0036] In a preferred embodiment, the evaluation module is configured to terminate the output of the warning message if a value of a later time interval deviates from the value of at least one earlier time interval by at least the negative minimum difference. In other words, the opposite condition to the condition that triggered the warning message is used to cancel the warning message. This also applies analogously to the use of the negative trend threshold or a comparable evaluation based on mean values, etc.

[0037] For example, the warning message will stop being issued when the pilot exits the aircraft, causing the pressure force values ​​to deviate again by the negative minimum difference. For example, the alarm or warning message will be triggered when the values ​​decrease and will stop when the values ​​increase.

[0038] Alternatively or additionally, it is also conceivable that the warning message can be terminated by manual acknowledgment, for example, by pressing a button on the tail roller, or that the warning message can be terminated automatically when the tail roller or the retaining part is released or removed from the aircraft. This can also be monitored by appropriate sensors, which are then linked to the evaluation module.

[0039] In general, all of the mechanisms and procedures explained above for triggering the warning message can also be used in the opposite direction to cancel / terminate the warning message.

[0040] The object of the invention is also achieved by a method according to claim 12. This method serves to monitor the aforementioned aircraft. The following steps are carried out using the tail roller according to the invention: Before the aircraft takes off, the tail dolly is attached to the aircraft. Subsequently, the evaluation module records or determines at least one (first) pressure force value in a first time interval. For example, the aircraft still has a weight distribution that must necessarily change before a possible takeoff. For example, there is no pilot in the aircraft during the first time interval, but the pilot's entry into the aircraft changes the weight ratios in such a way that this can be detected by the change in the pressure force on the tail roller.

[0041] From now on, the evaluation module will determine at least one (second) value for at least one subsequent time interval and, as explained above, will check whether the warning message should be issued and, if so, issue it.

[0042] In a later time interval, i.e. after the first time interval, at least one value is determined again.

[0043] If the aircraft then exhibits the (different) weight distribution required for takeoff, this is detected by a change in the values ​​of at least the minimum difference. For example, once the aircraft is crewed with the pilot required for takeoff, the tail load changes, and the warning message is issued. As explained above, the invention assumes that the pressure and force conditions on the aircraft then change in the assumed manner, meaning that the values ​​determined at the time intervals change and thus deviate from each other by more than the minimum difference, thus issuing the warning message.

[0044] In other words, the weight load / pressure / load on the tail dolly is used to monitor whether a pilot has boarded the aircraft and is therefore, in principle, ready for takeoff. If the tail dolly is still attached, it will alert the pilot with a warning message so that it can be removed in time before takeoff.

[0045] The method is specifically performed on a glider as an aircraft. Specifically, the first time interval occurs when the aircraft is still unoccupied. In other words, the tail roller is then initialized to the first determined value. Subsequent time intervals are cyclically monitored, for example, to determine whether the weight load on the aircraft has changed, which could indicate a pilot boarding, thus triggering the warning message.

[0046] The tail roller / method not only works under the condition that no crew is in the aircraft during system initialization (determination of the first value in the first time interval). The invention / system also works if a pilot is in the cockpit during the first time interval (e.g., engagement of the tail roller). However, this pilot must later exit the cockpit so that the system / tail roller can provide a reference value (value in the reference time interval). This behavior is sometimes used to make it easier to engage the tail roller. In this case, the system would initialize with the warning message "No alarm" even though a pilot is in the cockpit. If the pilot exits after initialization, the alarm is deactivated (exceeding the negative trend threshold: in this case, however, from the initial "No alarm" -> still "No alarm").If the pilot later re-enters the cockpit, the alarm status changes to “Alarm” (due to the negative load jump, i.e. the exceeding of the trend threshold) and the warning signal is issued.

[0047] In a preferred embodiment, the method is performed on an aircraft having a longitudinal axis. Furthermore, the aircraft has a support point at a central position along the longitudinal axis, where it rests on the ground during landing. In a glider, this is, for example, the main wheel. The support point can also be a support line; what is crucial is that the aircraft is mounted at the support point like a balance and is supported by the tail roller outside of this point / line, providing force-measuring support.

[0048] Furthermore, the aircraft only has seating positions for a specific user on one side (on one section) of the longitudinal axis relative to the center position. In particular, a glider, viewed in the direction of flight, only has pilot seating in front of the center position, i.e., in front of the main wheel. Therefore, only there can a significant increase in load on the front part of the aircraft, in front of the center position, occur. This increase in load leads to a reduction in the load on the rear of the aircraft via a leverage effect relative to the main wheel support point. This rear is located beyond the center position along the longitudinal axis.

[0049] Therefore, the procedure is performed on an aircraft that still has a designated mounting location for the tail dolly, which is located on the other side (other section) of the longitudinal axis. The other side is the one that is "opposite" the seating position with respect to the center position, for example, in the tail area of ​​the aircraft.

[0050] In particular, the procedure is carried out for an aircraft which has only one or two seats for one, two pilots or one pilot and one passenger.

[0051] In such aircraft, the assumptions underlying the functioning of the tail roller and its inherent warning system are certainly met. The tail roller can therefore reliably issue warning messages.

[0052] In particular, the following procedure is carried out and the spur roller is set up as follows: After a system start, the sensor (e.g., a load cell) and an alarm controller (e.g., alarm state = "No Alarm") are initialized. Subsequently, a timer call occurs every 2 ms, triggering the following: First, an alarm condition is checked.

[0053] If no alarm is currently being triggered ("No Alarm" status), continue to the procedure below ("Sampling time elapsed?"). If an alarm is currently being triggered ("Alarm" status), a check is made to see whether a switch is set to "Alarm on" or "off." If "on," an alarm tone is triggered and an alarm LED is activated; otherwise, only the alarm LED is activated.

[0054] It then checks whether a sampling time (e.g., 16 ms) has elapsed since the last sensor readout. If not, it waits for the next timer call.

[0055] Once the sampling time (16ms) has elapsed, the sensor is read out and the sensor values ​​(load values) are stored in a ring buffer.

[0056] Now it checks whether the ring buffer has been filled at least once. If not, it waits for the next timer call. Otherwise, it checks whether an evaluation time (e.g., 1 second) has elapsed since the ring buffer was last evaluated. If not, it also waits for the next timer call.

[0057] If so, the ring buffer is evaluated and a decision is made as to whether the alarm state should be set to "Alarm" or "No Alarm," or whether there should be no change in the alarm state. The system then waits for the next timer call.

[0058] The invention is based on the following findings, observations, and considerations and also includes the following preferred embodiments. These embodiments are sometimes referred to as "the invention" for simplicity. The embodiments may also contain parts or combinations of the above-mentioned embodiments or correspond to them and / or may also include previously unmentioned embodiments.

[0059] The invention is based on the observation that, despite proper pre-takeoff checks, gliders occasionally take off with the tail roller attached. Such a takeoff often results in a fatal crash for the occupants.

[0060] In practice, it was previously known to check the aircraft by means of visual inspection and checklists (“tail ball removed”).

[0061] The basic idea of ​​the invention is that a warning module (tail-roll warning module, evaluation module / sensor) monitors the tail load (tail load, weight at the tail) of the aircraft. When a pilot climbs into the cockpit, the weight at the rear of the aircraft decreases.

[0062] In contrast to the familiar checklist approach (which can overlook tail rollers), the warning module actively warns the user of a critical situation. Communication between a transmitter (sensor) and a receiver (display unit) is no longer necessary. The present invention results in a stand-alone module. Everything is thus contained in one module (tail roller or evaluation unit / sensor). This results in easier maintenance of the warning module and simpler installation on the aircraft.

[0063] According to the invention, the condition of the aircraft is measured by means of a force measurement. The tail load is also determined, thus providing information about the situation (pilot in the cockpit).

[0064] According to the invention, the aircraft is monitored by a warning module integrated into the tail roller. The force acting on the tail roller depends on the force acting on the cockpit. When a pilot enters the cockpit, the mass in the nose of the aircraft increases. Thus, the force acting on the tail roller decreases. This change in load is recorded and evaluated by the force sensor.

[0065] The tail load can therefore be used to determine whether a pilot is in the cockpit. Moving the aircraft causes load fluctuations that must be compensated for.

[0066] If a pilot is in the cockpit, a warning is issued. A warning can be given either via audible or visual signals. The tail load lowers when a pilot is in the cockpit.

[0067] The measured values ​​are evaluated by first removing measurement noise. This noise is then removed by averaging. The trend of the individual measured values ​​(X future averages relative to a past average) is then determined. These trends are summed to determine the total.

[0068] The invention provides a warning module that determines the cockpit status ("Pilot in cockpit?") using tail load measurements. This measurement module warns bystanders / the pilot if the aircraft attempts to take off despite the tail roller being engaged.

[0069] The invention provides a warning module for preventing glider takeoffs. The invention is intended to detect a tail roller that has been accidentally attached to the aircraft using a warning module integrated into the aircraft. The pilot is thus warned if a tail roller is mistakenly attached to the aircraft during takeoff.

[0070] Further features, effects, and advantages of the invention will become apparent from the following description of a preferred embodiment of the invention and the accompanying figures. Each of these figures shows a schematic diagram: Fig. 1 a glider in side view with mounted tail dolly, Fig. 2 the course of a pressure force recorded by a sensor in the spur roller over time for two time intervals, Fig. 3 an alternative course of the compressive force over five time intervals with mean values ​​and trend values, Fig. 4a the course Fig. 3 with associated trend values ​​with an evaluation of a first and Fig. 4b at a later date, Fig. 5a the temporal course of mean values ​​and trend values ​​for a constantly loaded aircraft and Fig. 5b when boarding and Fig. 5c when a pilot exits, Fig. 6 a chronological sequence of the pilot’s boarding and disembarkation in accordance with Fig. 5.

[0071] Fig. Figure 1 shows an aircraft 2 in the form of a glider. This has a longitudinal axis 6 along its flight direction 4. At a central position 8 of the longitudinal axis 6, the glider has a support point 10, at which it can be Fig. 1, the landing position L rests or can roll on a surface 12, here the ground. The support point 10 is formed by a main wheel of the aircraft 2 (not explained in detail).

[0072] With respect to the center position 8, i.e., in front of and behind it as seen in the direction of flight 4, the longitudinal axis 6 has two sides 14a, b or sections of the longitudinal axis 6. Only on side 14a of the longitudinal axis 6 does the aircraft 2 have two seating positions 16a, b for respective users of the aircraft 2 (not shown here), a pilot and a co-pilot or passenger. Therefore, only these two seating positions 16a, b can be used by users to fly with the aircraft 2.

[0073] On the other side 14b of the longitudinal axis 6 with respect to the central position 8, the aircraft 2 has a designated mounting location 18 for a tail dolly 20.

[0074] In Fig. 1, the tail dolly 20 is actually attached to the aircraft 2. The tail dolly 20 serves to support the aircraft 2 on the ground 12 and to enable maneuvering. The tail dolly 20 has a holding part 22, here an openable and closable sleeve, which is attached to the aircraft 2 in an assembled state M.

[0075] By opening the sleeve (not explained in detail), the retaining part 22 and thus the entire tail dolly 20 can be removed from the aircraft 2. Thus, the retaining part 22 and thus the entire tail dolly 20 are removably attached to the aircraft 2. The tail dolly 20 is therefore one that is intended to be attached to a tail 34 of the aircraft 2 and is actually attached here.

[0076] A wheel 24 is attached to the holding part 22, which wheel 24 rests on the ground 12 in the landing state L in the intended operation of the tail dolly 20 or aircraft 2 shown here, in order to rest or roll on it.

[0077] The tail dolly 20 also contains a sensor 26, in this case a force sensor. This sensor is used to detect a pressure force F exerted by the aircraft 2 on the tail dolly 20 or via the tail dolly 20 and the wheel 24 on the ground 12, in Fig. 1 symbolized by an arrow.

[0078] The spur roller 20 also contains an evaluation module 28. This is set up as follows:

[0079] Fig. For illustrative purposes, Figure 2 shows a diagram of a curve 30 of the pressure force F over time t. Shown are two consecutive time intervals I1 and I2, each lasting, for example, 30 seconds; however, the time interval can be freely selected. For each of the intervals I1,2, the evaluation module 28 records or determines a respective value W1,2 of the pressure force F. In this case, the value W1,2 is the respective mean value MW1,2 of the time curve 30 of the pressure force F within the intervals I1,2. The significant fluctuations in the shown curve 30 of the signal also arise, for example, from the maneuvering of aircraft 2.

[0080] According to Fig. 2, the curve 30 of the compressive force F is filtered within the respective time interval I1,2 to determine the respective value W1,2. The filtering here is an averaging process.

[0081] At time tE, a pilot (not shown) boards the aircraft 2 and takes a seat at seat position 16a.

[0082] The evaluation module 28 is also configured to output a warning message 32 if the value W2 of the later time interval I2 deviates from the value W1 of the earlier time interval W1 by at least a minimum difference DMIN. In this case, the minimum difference DMIN is a specific decrease in the value W2 compared to the value W1, which was actually exceeded here, which is why the warning message 32 is actually output. The minimum difference DMIN is therefore a minimum decrease in the value W over time t.

[0083] The warning message 32 is issued here as a combined audio and light signal, in which a warning light (not shown) on the support part 22 flashes and a loudspeaker (not shown) on the support part 22 emits a warning tone. Thus, audio and light signals are generated.

[0084] The evaluation module 28 is configured to transmit the warning message 32 to the vicinity 36 of the aircraft 2. For safety reasons, it is thus perceived by the pilot himself, as well as by bystanders and an air traffic control officer. All relevant persons are thus made aware of the necessary removal of the tail roller 20 before takeoff of the aircraft 2. In particular, the air traffic control officer can deny takeoff permission for the aircraft 2 until the tail roller 20 is removed.

[0085] Only by removing the spur roller 20 does the warning message 32 automatically disappear due to a sensor system in the holding part 22 that is not explained in more detail.

[0086] The following procedure is carried out to monitor the aircraft 2 using the tail dolly 20: Before takeoff of the aircraft 2, the tail dolly 20 is attached to the aircraft as shown in Fig. 1 is shown.

[0087] In the first time interval I1, the first value W1 is determined. During this time interval I1, the aircraft still has a weight distribution that must change before takeoff: This is because there is currently no pilot on board, although this is essential for the aircraft's flight. However, the weight distribution inevitably changes when the pilot boards the aircraft. The weight distribution is the ratio of the weight of a nose mass 40 to the weight of the tail mass 42 of aircraft 2 (including all current loads and passengers).

[0088] From now on, at least one value (here, the value W2) is determined for at least one subsequent time interval (here, the time interval I2), and the evaluation module 28 checks whether warning message 32 should be issued. Depending on the result (here, positive), warning message 32 is issued. In detail: When the pilot boards the aircraft at time tE, here at seat position 16a, a significant weight is placed on the aircraft, which is why the tail 34 of the aircraft (leverage via support point 10) is relieved. This is because the nose mass 40 increases, while the tail mass 42 remains unchanged. The leverage or balance principle at pivot point 44 (support point 10) results in the following: The tail 34 presses on the tail dolly 20 with less pressure force F, and the wheel 24 presses on the ground 12 with less pressure force F. This change in force is recorded by sensor 26 as curve 30 of the pressure force F, and the change is determined by the value W2 being smaller than the value W1. Since the minimum difference DMIN is exceeded here, it can be concluded that the pilot has boarded the aircraft. Sensor 26 is continuously read on the tail dolly 20, and the pressure force F is determined as curve 30.Thus, at least one pressure value W2 is also determined in a subsequent time interval I2, after the aircraft has been loaded with the pilot required for takeoff. This leads to the procedure described above, namely, that warning message 32 is issued if the value W2 of a subsequent time interval I2 deviates from a previous value W1 of a previous time interval I1 by at least the minimum difference DMIN.

[0089] The method is carried out here on the aircraft 2, which, as described above, has longitudinal axis 6, center position 8, seat positions 16a,b and mounting location 18 for the tail dolly 20.

[0090] Fig. 1 also symbolically shows the basic principle of the present invention, namely that the tail dolly 20 or its sensor 26 evaluates a relationship between the nose mass 40 and the tail mass 42 with respect to the pivot point 44, here the main landing gear as the only support point 10 (besides the tail dolly 20) on the aircraft 2. Depending on how the relationships between the nose mass 40 and the tail mass 42 shift relative to each other, the warning message 32 is issued or not. The basic principle is symbolically represented by a scale with a support point at the pivot point 44. The respective mass is indicated here by curly brackets.

[0091] Fig. Figure 3 shows an alternative curve 30 of the compressive force F. The evaluation here also includes filtering in the form of averaging. Therefore, in each of the time intervals I0-4, the corresponding mean value MW0-4 is calculated as the respective value W0-4 across all values ​​of the compressive force F within the respective interval I0-4.

[0092] Fig. 4a shows again the situation Fig. 3, however, the underlying curve 30 of the compressive force F has been omitted for clarity. Therefore, only the mean values ​​MW0-4 are shown. Alternatively, the filtering here also includes the determination of trend values ​​TW1-4 as part of the values ​​W1-4, which here are value tuples consisting of the mean and trend values: The tendency value TW1-4 corresponds to the respective difference of the mean value MW1-4 of the time interval 11-4 relative to the mean value MW0 of the reference time interval I0. Fig. Figure 4a shows an example in which interval I1 has a tendency value TW1 of +10 relative to interval I0, in interval I2 of TW2=-10, in interval I3 of TW3=-5 and in interval I4 of TW4=-3.

[0093] Furthermore, the four trend values ​​TW1-4 of the intervals I1 to I4 are averaged. This results in (+10 -10 -5 -3) / 4 = -2 as the average trend value.

[0094] Fig. Figure 4b shows the evaluation at a later time (interval I1) after the expiration of the time interval I0. The reference time interval is now interval I1. The trend values ​​related to this are: I2=-20, I3=-15, I4=-12, and I5=-9 (not shown).

[0095] Here, too, an average of the four trend values ​​TW2-5 of intervals I2 to I5 is calculated, now relative to interval I1. This results in (-20 -15 -12 -9) / 4 = -14 as the average trend value.

[0096] A trend threshold in this case is -6.

[0097] The evaluation unit 28 only issues the warning message if the average trend value is above the threshold value. Fig. 4a, therefore, no warning message 32 is issued in the situation according to Fig. 4b already.

[0098] Fig. 5a-c show different tendencies for different load profiles / load changes over time t, whereby the upper diagram always shows the temporal course of the mean values ​​over time t and the lower diagram shows the corresponding temporal course of the trend values ​​over time t.

[0099] Fig. Figure 5a shows the situation in which aircraft 2 remains unoccupied over time t; the mean values ​​fluctuate only slightly, and the tendencies practically average out over time t.

[0100] Fig. Figure 5b shows the boarding of a pilot: the mean values ​​decrease, the trends are almost exclusively clearly negative.

[0101] Fig. Figure 5c shows the exit of a pilot and thus an increase in the mean values ​​and almost exclusively positive trend values.

[0102] Fig. 6 shows the three situations from Fig. 5a-c are arranged logically in chronological order. The value line here is a classification template for the decision (is an alarm present?). The intersection points of the curly brackets are decision thresholds: boarding at time tE in (evaluation area / evaluation section A, multiple time intervals), remaining in (evaluation section B, multiple time intervals), and disembarking at time tA of the pilot (evaluation section C, multiple time intervals) from aircraft 2.

[0103] Due to the exceedance of the trend threshold in Fig.6 In time period A, warning message 32 is triggered or issued for the first time. In time period B, warning message 32 is maintained; in time period C, warning message 32 is terminated because the negative trend threshold is exceeded, which correctly indicates that the pilot has bailed out. Thus, in time period C, there is no longer any risk of aircraft 2 taking off, and tail roller 20 does not need to be removed from aircraft 2.

[0104] The warning message 32 is therefore issued until the evaluation module 28 determines that the trend value averaged over several time intervals deviates from the value of the reference time interval by at least the negative trend threshold value. List of reference symbols 2 aircraft 4 Flight direction 6 Longitudinal axis 8 Middle position 10 support point 12 Underground 14a,b side (longitudinal axis) 16a,b Sitting position 18 Installation location 20 spur balls 22 Holding part 24 wheel 26 Sensor 28 Evaluation module 30 Course (pressure force, time) 32 Warning message 34 rear 36 Surroundings 40 bow mass 42 rear mass 44 Pivot point L Landing condition M Assembly state F compressive force t time I0-4 interval W0-4 value DMIN Minimum difference MW0-4 mean TW1-4 tendency value AC evaluation section tE,A time

Claims

[1] Tail dolly (20) for supporting and maneuvering an aircraft (2) on a surface (12), - with a holding part (22) which can be removably attached to the aircraft (2) in an assembled state (M), - with a wheel (24) attached to the holding part (22) which rests on a base (12) during normal operation of the spur roller (20), - with a sensor (26) for detecting a pressure force (F) exerted by the aircraft (2) via the tail roller (20) on the ground (12), - with an evaluation module (28) which is designed to - to determine a respective value (W0-4) of the compressive force (F) for at least two consecutive time intervals (I0-4), - to output a warning message (32) if a value (W0-4) of a later time interval (I0-4) deviates from the value (W0-4) of at least one earlier time interval (I0-4) by at least a minimum difference (DMIN). [2] Spur roller (20) according to claim 1, characterized by that the tail dolly (20) is one that is intended to be attached to a tail (34) of the aircraft (2). [3] Spur roller (20) according to one of the preceding claims, characterized by that the tail dolly (20) is one that is intended to be attached to a glider as an aircraft (2). [4] Spur roller (20) according to one of the preceding claims, characterized by that the minimum difference (DMIN) is a minimum decrease in the value (W0-4) over time (t). [5] Spur roller (20) according to one of the preceding claims, characterized by that the evaluation module (28) is designed to determine at least one of the values (W0-4) by filtering a detected curve (32) of the compressive force (F). [6] Spur roller (20) according to claim 5, characterized bythat the filtering includes the formation of an average value (MW0-4) of the curve (32) of the pressure force (F). [7] Spur roller (20) according to one of claims 5 to 6, characterized by that the filtering includes a determination of a trend value (TW1-4) of the compressive force (F) in the time interval (I0-4) related to a value (W0-4) of a previous reference time interval (I0-4). [8] Spur roller (20) according to claim 7, characterized by that the evaluation module (28) is set up to only output the warning message (32) when the trend values (TW1-4) averaged over several time intervals (I0-4) deviate from the value (W0-4) of the reference time interval (I0-4) by at least one trend threshold value. [9] Spur roller (20) according to one of the preceding claims, characterized by that the evaluation module (28) is configured to output the warning message (32) to an environment (36) of the spur roller (20). [10] Spur roller (20) according to one of the preceding claims, characterized by that the evaluation module (28) is designed to output the warning message (32) as an audio and / or light signal. [11] Spur roller (20) according to one of the preceding claims, characterized by in that the evaluation module (28) is designed to terminate the output of the warning message (32) if a value (W0-4) of a later time interval (I0-4) deviates from the value (W0-4) of at least one earlier time interval (I0-4) by at least the negative minimum difference (DMIN). [12] Method for monitoring an aircraft (2), in which with the aid of a tail roller (20) according to one of the preceding claims: - before take-off of the aircraft (2), the tail roller (20) is attached to the aircraft (2), - the evaluation module (28) determines at least one value (W0-4) in a first time interval (I0-4), - from then on, the evaluation module (28) determines at least one value (W0-4) for at least one later subsequent time interval (I0-4) and checks whether the warning message (32) is to be output and outputs it if necessary. [13] Method according to claim 12, characterized by that the method is carried out on an aircraft (2) which has: - a longitudinal axis (6), - at a central position (8) of the longitudinal axis (6) a support point (10) at which it rests on the ground (12) in the landing state (L), - has seating positions (16a,b) for a respective user of the aircraft (2) exclusively on one side (14a) of the longitudinal axis with respect to the central position (8), - has a designated mounting location (18) for the spur roller (20) on the other side (14b) of the longitudinal axis (6).

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