A method for designing a power limitation of a tail rotor of a helicopter
Patent Information
- Application Number
- CN202510418148.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-03
- Publication Date
- 2026-10-16
AI Technical Summary
以往关于直升机尾桨限制功率的设计主要是经验公式，定量化设计成熟度较低，不再满足直升机精细化设计要求
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Figure CN122926596A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of flight mechanics technology, and in particular relates to a design method for limiting the power of a helicopter tail rotor. Background Technology
[0002] The design of power limiting for the tail rotor of conventional configuration helicopters plays a crucial role in tail rotor drive design, tail rotor load assessment, and flight usage restrictions. The flight states that affect the power limiting of the tail rotor in conventional configuration helicopters are hovering turns and high-speed sideslip flight. The latter is a quasi-steady state and can be calculated using existing conventional flight performance analysis models with sideslip analysis capabilities; while the former is actively induced by the pilot, as illustrated in the maneuver diagram. Figure 1 It is necessary to consider the changes in tail rotor control over time and capture the peak thrust and power of the tail rotor during hovering and turning maneuvers. In the past, the design of tail rotor power limits for helicopters was mainly based on empirical formulas, and the maturity of quantitative design was low, which no longer meets the requirements of refined helicopter design. Summary of the Invention
[0003] To meet the requirements of quantitative and refined helicopter design, this invention provides a method for designing tail rotor power limitation. This invention targets the design of tail rotor power limitation, decomposes the hovering and turning maneuver process, and establishes a simulation calculation method for the time-varying tail rotor control. This method can accurately capture the peak tail rotor thrust and power during hovering and turning maneuvers, thereby completing the tail rotor power limitation design.
[0004] To achieve the above objectives, the present invention employs the following technical solution.
[0005] A method for limiting the power of a helicopter tail rotor, wherein the power limit occurs during the helicopter's hovering and turning maneuver, the hovering and turning maneuver phase including: a target hovering and turning phase, a stable hovering and turning phase, and a counter-steering hovering and turning phase; the method includes:
[0006] S1, determine the target hovering angular velocity during the hovering and turning maneuver phase;
[0007] S2, in any of the three stages, by adjusting the control timing point of collective pitch control direction reversal, a collective pitch control time curve is generated.
[0008] S3, calculate the peak hovering angular velocity based on the collective pitch control time curve;
[0009] S4. If the peak hovering angular velocity deviates from the target hovering angular velocity, the control timing of the collective pitch control direction is adjusted until the peak hovering angular velocity is equal to the target hovering angular velocity, and the collective pitch peak values corresponding to the three stages are obtained respectively.
[0010] S5, based on the maximum value of the collective pitch peak corresponding to the three stages, obtains the maximum power of the helicopter tail rotor.
[0011] Furthermore, in S1, the target hovering angular velocity is obtained based on the quality level standard of hovering angular velocity given in the flight quality specification.
[0012] Furthermore, in S2, the collective pitch is increased based on the given maximum collective pitch speed, and then the collective pitch is decreased based on the given maximum collective pitch speed. By adjusting the control timing point of the collective pitch control direction reversal, a time curve for collective pitch control is generated.
[0013] Furthermore, in S3, the tail rotor thrust T TR (ω,θ T ) represents the angular velocity ω and the collective pitch θ of the tail rotor. T The function;
[0014] Determine the angular acceleration and collective pitch θ of the tail rotor T The expression;
[0015] Integrating the angular acceleration, we obtain the peak hovering angular velocity.
[0016] Furthermore, the method also includes: during the stable hovering and turning phase,
[0017] Based on the control time point determined by S4, the time history curve of collective pitch control is generated by adjusting the minimum limit collective pitch.
[0018] Based on the time history curve of the collective pitch control, the final angular velocity is calculated; the final angular velocity is the angular velocity corresponding to the collective pitch remaining constant.
[0019] The ending turning angular velocity is compared with the target turning angular velocity. If the ending turning angular velocity deviates from the target hovering turning angular velocity, the minimum limit collective distance is adjusted until the ending turning angular velocity is equal to the target hovering turning angular velocity, thus obtaining the minimum limit collective distance.
[0020] Furthermore, during the reverse-push hovering and turning phase, S2 specifically refers to:
[0021] The process of generating a collective pitch control time curve involves two control points at which the collective pitch control direction is adjusted.
[0022] The first step is the process of accelerating to the target hovering turning angular velocity at the fastest speed;
[0023] The second process involves reversing at the fastest speed to the target in the opposite direction and hovering to restore the angular velocity.
[0024] Furthermore, the target hovering and turning phase specifically includes:
[0025] During the acceleration phase, the pilot depresses the pedals at the fastest speed to perform hovering turn acceleration; during the counter-push phase, the pilot depresses the pedals at the fastest speed to reduce hovering turn acceleration. At this time, the tail rotor collective pitch is greater than the collective pitch required to maintain the heading, and the hovering turn angular velocity is still increasing until the target hovering turn angular velocity is reached; at the instant of counter-push, the tail rotor collective pitch reaches the peak value of the entire maneuver, corresponding to the peak value of tail rotor thrust and power.
[0026] Furthermore, the stable hovering and turning phase specifically includes:
[0027] Based on the target hovering and turning phase, during the counter-push phase, the collective pitch of the tail rotor remains at the collective pitch value required to maintain the target hovering and turning angular velocity, so the hovering and turning angular velocity will remain at the target value.
[0028] Furthermore, the specific steps of the reverse pedaling hovering and turning phase are as follows:
[0029] Based on the target hovering and turning phase, an additional reversal phase is added to achieve the target hovering and turning angular velocity in another direction. This increases the tail rotor collective pitch to a larger peak value, so the reversal hovering and turning will generate greater tail rotor power and thrust.
[0030] Based on the aforementioned method for solving hovering and turning maneuvers, the tail rotor power can be calculated under different conditions and tail rotor control limitations. This allows for the determination of the tail rotor power limit that may occur during hovering and turning maneuvers, thus enabling the quantitative design of tail rotor power limitations. Compared to traditional empirical formula design methods, this method significantly improves calculation accuracy and meets the requirements of modern helicopter fine-tuning design. This method can also meet the power calculation needs for hovering and turning states in the power spectrum. Attached Figure Description
[0031] Figure 1 A flowchart illustrating a helicopter tail rotor power limiting design method provided in an embodiment of the present invention;
[0032] Figure 2 This is a schematic diagram of the target hovering and turning stage provided in an embodiment of the present invention;
[0033] Figure 3 This is a schematic diagram of the components of the stable hovering and turning stage provided in an embodiment of the present invention;
[0034] Figure 4 This is a schematic diagram of the components of the anti-push-alert hovering and turning stage provided in an embodiment of the present invention;
[0035] Figure 5 This is a schematic diagram of the target hovering and rotation solution process provided in an embodiment of the present invention;
[0036] Figure 6This is a schematic diagram of the stable hovering and rotation solution process provided in an embodiment of the present invention;
[0037] Figure 7 This is a schematic diagram of the solution process for reverse pedaling hovering and turning provided in an embodiment of the present invention. Detailed Implementation
[0038] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.
[0039] The purpose of hovering and turning is to quickly and accurately adjust the helicopter's maneuvering direction. Flight quality specifications require the total time and stopping angle accuracy for a helicopter to complete a 180-degree hovering turn, thereby determining the flight quality level.
[0040] The maximum power of the tail rotor is mainly related to the angular velocity of hovering turns. Therefore, the hovering turns involved in flight performance analysis are all extreme hovering turns aimed at a given hovering turn angular velocity. An extreme hovering turn maneuver refers to increasing collective pitch at a given collective pitch speed (representing the pilot pedaling at maximum speed) and then decreasing collective pitch at a given collective pitch speed (representing the pilot pedaling back at the maximum speed to reduce the increase in turn angular velocity in order to control the peak hovering turn angular velocity at a given value). In this way, the maximum possible tail rotor collective pitch can be excited under a given control rate and hovering turn angular velocity, thus obtaining the tail rotor thrust and power under extreme conditions.
[0041] Analyzing the torque along the Z-axis in the rotation direction, the fuselage angular acceleration can be obtained as follows. Since the rotational angular velocity ω changes the tail rotor inflow velocity, the tail rotor thrust T... TR (ω,θ T It is significantly affected by the angular velocity of the turning wheel and the collective pitch θ of the tail rotor. T The effects are the angular velocity ω and the collective pitch θ of the tail rotor. T The function is used to establish the collective pitch θ of the tail rotor. T The impact on hovering and turning maneuvers; the yaw torque M of the main rotor about the center of gravity. MR Since the main rotor speed is significantly greater than the rotational speed ω, it basically does not change with the rotational speed ω and can be considered constant, the same as in the stable hovering trim state; L TR I is the lever arm of the tail rotor thrust to the center of gravity. ZZ This refers to the moment of inertia of the fuselage's axis of rotation. It is particularly important to emphasize L. TR The lever arm is to the center of gravity, not to the main rotor shaft. This shows that the tail rotor lever arm is short in the rear center of gravity state, which is a harsh state of hovering and turning, consistent with the actual situation.
[0042]
[0043] Therefore, based on the time step ΔT, the first-order partial differential equation can be established as follows.
[0044]
[0045] This invention provides a method for designing power limiting for helicopter tail rotors. This invention targets the design of power limiting for helicopter tail rotors, decomposes the hovering and turning maneuver process, and establishes a simulation calculation method for tail rotor control changes over time. This method can accurately capture the peak thrust and power of the tail rotor during the hovering and turning maneuver, thereby completing the design of tail rotor power limiting.
[0046] Based on the characteristics of hovering and turning maneuvers, hovering and turning maneuvers can be divided into three typical types, as follows:
[0047] a) Target Hover Turn: A hover turn that accelerates to the target angular velocity as quickly as possible and then reverses. During the acceleration phase, the pilot depresses the accelerator pedals at maximum speed to accelerate for the hover turn; during the depressor phase, the pilot depresses the accelerator pedals at maximum speed to reduce the acceleration, but the tail rotor collective pitch is still greater than the collective pitch required to maintain heading, so the hover angular velocity continues to increase until the target hover angular velocity is reached. At the moment of depressor, the tail rotor collective pitch reaches its peak value during the entire maneuver, corresponding to the peak tail rotor thrust and power, which is the key focus of hover turn maneuver analysis. During the reversal phase, the angular velocity begins to decrease from the target angular velocity. This method can excite the maximum collective pitch angle at the target hover angular velocity, thus obtaining the peak tail rotor thrust and power that may occur during the hover turn. See the specific diagram below. Figure 2 .
[0048] b) Stable hovering turn: A stable hovering turn achieved by accelerating to the target angular velocity as quickly as possible. Building upon the maneuver in a), the tail rotor collective pitch remains at the value required to maintain the target angular velocity during the pushback phase, thus keeping the hovering angular velocity at the target value. The tail rotor collective pitch does not peak during the stable hovering turn, therefore it does not affect the peak tail rotor thrust and power results obtained from a). See the detailed diagram below. Figure 3 .
[0049] Reverse-push hover turn: A hover turn that accelerates to the target yaw rate as quickly as possible, then reverses to the target yaw rate in the opposite direction as quickly as possible. It adds a reversal segment to maneuver a), reaching the target hover yaw rate in the opposite direction. Because the reverse yaw rate accelerates from -24° / s to 24° / s, the reverse-push segment, compared to maneuver a) which accelerates from 0° / s to 24° / s, results in a larger peak tail rotor collective pitch. Therefore, the reverse hover turn generates greater tail rotor power and thrust. Many helicopters limit the reverse-push during hover turns, including the duration and speed of the reverse-push, to avoid the load caused by the reverse-push during hover turns. See the diagram for a specific example. Figure 4 .
[0050] The solution process is as follows:
[0051] Starting from the first level, the solution for the current stage is completed iteratively in the second level. During this process, the third level is called to obtain timing results. After completing the first level's stage progression, a complete hovering turn solution that meets expectations is obtained, thus completing the solution. Schematic diagrams of the solution flowcharts for target hovering turn, stable hovering turn, and reverse-push hovering turn are shown below. Figure 5 , Figure 6 , Figure 7 .
[0052] Target hovering and turning:
[0053] For the design phase, the hovering turn rate quality level standard given by the flight quality specification guides the hovering turn maneuver analysis in the design phase. Based on this, the first level proposes the current stage target hovering turn rate.
[0054] The control timing is determined by increasing the collective pitch at a given collective pitch speed (representing the pilot pedaling at maximum speed) and then decreasing the collective pitch at the same speed (representing the pilot using extreme counter-pumping to reduce the increase in angular velocity in order to control the peak hovering angular velocity within a given value). By adjusting the control timing of the collective pitch control direction, a collective pitch control time curve is generated and passed to the third level for time series solution. The time series returned from the third level yields the corresponding extreme angular velocity solution. The extreme angular velocity solution is compared with the angular velocity target from the first level to identify deviations. The control timing is then adjusted iteratively until the angular velocity solution matches the target, completing the second level solution.
[0055] Stable hovering and turning
[0056] For the design phase, the hovering turn rate quality level standard given by the flight quality specification guides the hovering turn maneuver analysis in the design phase. Based on this, the first level proposes the current stage target hovering turn rate.
[0057] The control timing is determined by increasing the collective pitch at a given collective pitch speed (representing the pilot pedaling at maximum speed) and then decreasing the collective pitch at the same speed (representing the pilot using extreme counter-pumping to reduce the increase in angular velocity in order to control the peak hovering angular velocity within a given value). By adjusting the control timing of the collective pitch control direction, a collective pitch control time curve is generated and passed to the third level for time series calculation. The time series returned from the third level yields the corresponding extreme angular velocity solution. The extreme angular velocity solution is compared with the angular velocity target from the first level to identify deviations. The control timing is then adjusted iteratively until the angular velocity solution matches the target.
[0058] The minimum limiting collective pitch (tail rotor collective pitch corresponding to stable hovering turn) is determined. Based on the control time points determined above, the minimum limiting collective pitch is adjusted to generate a time history curve of collective pitch control, which is then passed to the third layer for time series solution. The result of the final turn angular velocity solution is compared with the turn angular velocity target from the first layer to obtain the turn angular velocity deviation. The minimum limiting collective pitch is then adjusted accordingly. Through iteration, the final turn angular velocity solution is made consistent with the turn angular velocity target. The stable turn solution is then completed.
[0059] Reverse pedal hovering and turning
[0060] For the design phase, the hovering turn rate quality level standard given by the flight quality specification guides the hovering turn maneuver analysis in the design phase. Based on this, the first level proposes the current stage target hovering turn rate.
[0061] The first control timing is determined by increasing the collective pitch based on a given collective pitch velocity (representing the pilot pedaling at maximum speed), and then decreasing the collective pitch based on the same velocity (representing the pilot using extreme counter-pumping to reduce the increase in angular velocity in order to control the peak hovering angular velocity within a given value). This initial adjustment of the collective pitch control direction generates a collective pitch control time curve, which is then passed to the third layer for time series calculation. The time series returned from the third layer yields the corresponding extreme angular velocity solution. Comparing this extreme angular velocity solution with the angular velocity target from the first layer reveals any deviations. The control timing is then adjusted iteratively until the angular velocity solution aligns with the target.
[0062] The second control timing point is determined by adjusting the control timing point for the second collective pitch maneuver. This generates a collective pitch maneuver time curve, which is then passed to the third layer for time series calculation. The time series returned from the third layer yields the corresponding extreme value of the counter-push turning angular velocity. This extreme value is compared with the turning angular velocity target from the first layer to identify deviations. The second control timing point is then adjusted, and through iteration, the counter-push turning angular velocity solution is made consistent with the target. This completes the counter-push turning angular velocity solution.
[0063] Based on the aforementioned method for solving hovering and turning maneuvers, the tail rotor power can be calculated under different conditions and tail rotor control limitations. This allows for the determination of the tail rotor power limit that may occur during hovering and turning maneuvers, thus enabling the quantitative design of tail rotor power limitations. Compared to traditional empirical formula design methods, this method significantly improves calculation accuracy and meets the requirements of modern helicopter fine-tuning design. This method can also meet the power calculation needs for hovering and turning states in the power spectrum.
Claims
1. A method for limiting the power of a helicopter tail rotor, characterized in that, The maximum power occurs during the helicopter hovering and turning maneuver, which includes: a target hovering and turning phase, a stable hovering and turning phase, and a counter-push hovering and turning phase; the method includes: S1, determine the target hovering angular velocity during the hovering and turning maneuver phase; S2, in any of the three stages, by adjusting the control timing point of collective pitch control direction reversal, a collective pitch control time curve is generated. S3, calculate the peak hovering angular velocity based on the collective pitch control time curve; S4. If the peak hovering angular velocity deviates from the target hovering angular velocity, the control timing of the collective pitch control direction is adjusted until the peak hovering angular velocity is equal to the target hovering angular velocity, and the collective pitch peak values corresponding to the three stages are obtained respectively. S5, based on the maximum value of the collective pitch peak corresponding to the three stages, obtains the maximum power of the helicopter tail rotor.
2. The helicopter tail rotor power limiting design method according to claim 1, characterized in that, In S1, the target hovering angular velocity is obtained based on the quality level standard of hovering angular velocity given in the flight quality specification.
3. The helicopter tail rotor power limiting design method according to claim 1, characterized in that, In S2, the collective pitch is increased based on the given maximum collective pitch speed, and then the collective pitch is decreased based on the given maximum collective pitch speed. By adjusting the control timing point of the collective pitch control direction reversal, a time curve for collective pitch control is generated.
4. The helicopter tail rotor power limiting design method according to claim 1, characterized in that, In S3, the tail rotor thrust T TR (ω,θ T ) represents the angular velocity ω and the collective pitch θ of the tail rotor. T The function; Determine the angular acceleration and collective pitch θ of the tail rotor T The expression; Integrating the angular acceleration, we obtain the peak hovering angular velocity.
5. The helicopter tail rotor power limiting design method according to claim 1, characterized in that, The method further includes: during the stable hovering and turning phase... Based on the control time point determined by S4, the time history curve of collective pitch control is generated by adjusting the minimum limit collective pitch. Based on the time history curve of the collective pitch control, the final angular velocity is calculated; the final angular velocity is the angular velocity corresponding to the collective pitch remaining constant. The ending turning angular velocity is compared with the target turning angular velocity. If the ending turning angular velocity deviates from the target hovering turning angular velocity, the minimum limit collective distance is adjusted until the ending turning angular velocity is equal to the target hovering turning angular velocity, thus obtaining the minimum limit collective distance.
6. The helicopter tail rotor power limiting design method according to claim 1, characterized in that, During the reverse-push hovering and turning phase, S2 specifically refers to: The process of generating a collective pitch control time curve involves two control points at which the collective pitch control direction is adjusted. The first step is the process of accelerating to the target hovering turning angular velocity at the fastest speed; The second process involves reversing at the fastest speed to the target in the opposite direction and hovering to restore the angular velocity.
7. The helicopter tail rotor power limiting design method according to claim 1, characterized in that, The target hovering and turning phase is specifically as follows: During the acceleration phase, the pilot depresses the pedals at the fastest speed to perform hovering turn acceleration; during the counter-push phase, the pilot depresses the pedals at the fastest speed to reduce hovering turn acceleration. At this time, the tail rotor collective pitch is greater than the collective pitch required to maintain the heading, and the hovering turn angular velocity still increases until the target hovering turn angular velocity is reached; at the instant of counter-push, the tail rotor collective pitch reaches the peak value of the entire maneuver, corresponding to the peak value of tail rotor thrust and power.
8. The helicopter tail rotor power limiting design method according to claim 1, characterized in that, The stable hovering and turning phase specifically includes: Based on the target hovering and turning phase, during the counter-push phase, the collective pitch of the tail rotor remains at the collective pitch value required to maintain the target hovering and turning angular velocity, so the hovering and turning angular velocity will remain at the target value.
9. The helicopter tail rotor power limiting design method according to claim 1, characterized in that, The specific steps of the reverse pedaling hovering and turning phase are as follows: Based on the target hovering and turning phase, an additional reversal phase is added to achieve the target hovering and turning angular velocity in another direction. This increases the tail rotor collective pitch to a larger peak value, so the reversing hovering and turning will generate greater tail rotor power and thrust.