Front landing gear and aircraft

Abstract

The present disclosure relates to the technical field of aircraft structures, and particularly relates to a front landing gear and an airplane. The front landing gear comprises a buffer strut, a rotating sleeve sleeved on the buffer strut and rotating around an axis of the buffer strut, a rudder mechanism fixedly connected to the buffer strut and connected to the rotating sleeve through a first rocker arm, a pendulum damper fixedly connected to the buffer strut and connected to the rotating sleeve through a second rocker arm, a wheel fork connected to the buffer strut, and a wheel assembly rotatably connected to the wheel fork. In this way, the rudder mechanism and the pendulum damper are connected in parallel, and the torque transmission paths are relatively independent. During the steering of the front landing gear, the shock absorber can exhibit a low-damping characteristic, and the interference with the steering torque is small, avoiding the situation that the front landing gear is not sensitive enough to respond when rectifying at a small angle, and avoiding the situation that the motor of the rudder mechanism needs to bear the damping torque generated by the pendulum damper when the pendulum damper is damping, thereby reducing the damage to the rudder mechanism.

Description

Technical Field

[0001] This disclosure relates to the technical field of aircraft structures, and more particularly to a nose landing gear and an aircraft. Background Technology

[0002] In related technologies, the nose landing gear of drones typically uses only a steering servo. Without a damper, the shimmy torque generated by ground shimmy is transmitted entirely to the fuselage through the servo's output shaft without any dissipation. Repeated exposure to alternating loads significantly impacts the output accuracy of the servo, affecting its lifespan. Even when a damper is used in the nose landing gear, it's usually a steering damping system where the steering servo and damper are connected in series. In this structure, the damper must be compressed before turning, resulting in insufficient responsiveness for small-angle corrections. Furthermore, the motor needs to withstand the damping torque generated by the damper during damping, which can cause significant damage to the motor, especially considering the higher precision of the servo.

[0003] Therefore, it is necessary to propose a nose landing gear and aircraft to at least partially solve the problems existing in the prior art. Utility Model Content

[0004] This disclosure aims to address at least one of the technical problems existing in the prior art or related technologies.

[0005] Therefore, the first aspect of this disclosure proposes a front landing gear;

[0006] The second aspect of this disclosure proposes an aircraft.

[0007] In view of this, a front landing gear is provided according to a first aspect embodiment of the present disclosure, comprising:

[0008] Buffer pillars;

[0009] A rotating sleeve is fitted onto the aforementioned buffer support column, and the rotating sleeve rotates around the axis of the aforementioned buffer support column;

[0010] A turning servo is fixedly connected to the aforementioned buffer support, and the turning servo is connected to the aforementioned rotating sleeve via a first rocker arm;

[0011] The sway damper is fixedly connected to the aforementioned buffer support column, and the sway damper is connected to the aforementioned rotating sleeve via a second rocker arm;

[0012] Wheel fork, connected to the aforementioned buffer support;

[0013] The wheel assembly is rotatably connected to the aforementioned wheel fork.

[0014] In one feasible implementation, the aforementioned front landing gear further includes:

[0015] The torque arm assembly is disposed between the aforementioned rotating sleeve and the aforementioned wheel fork.

[0016] In one feasible implementation, the above-mentioned torque arm assembly includes:

[0017] The first torque arm is connected to the aforementioned rotating sleeve via the first connecting bolt;

[0018] The second torque arm is connected to the aforementioned wheel fork via a second connecting bolt;

[0019] The first torque arm is connected to the second torque arm via a pin.

[0020] The first torque arm can rotate around the first connecting bolt; the second torque arm can rotate around the second connecting bolt; and both the first torque arm and the second torque arm can rotate around the pin.

[0021] In one feasible implementation, the aforementioned buffer support, the output shaft of the aforementioned steering servo, the aforementioned first rocker arm, and the aforementioned rotating sleeve together form a four-bar linkage mechanism, and the aforementioned wheel fork is driven through the aforementioned four-bar linkage mechanism when steering.

[0022] In one feasible implementation, the aforementioned buffer pillar includes:

[0023] The main support body, the aforementioned rotating sleeve is fitted onto the main support body, and the aforementioned steering servo and the aforementioned damper are both fixedly connected to the main support body;

[0024] A buffer mechanism is provided inside the main body of the aforementioned support column, and the aforementioned wheel fork is connected to the aforementioned buffer mechanism.

[0025] In one feasible implementation, the buffer mechanism is a hydropneumatic buffer mechanism, and the wheel fork is connected to the piston rod of the hydropneumatic buffer mechanism.

[0026] In one feasible implementation, the aforementioned wheel assembly includes:

[0027] The axle is connected to the aforementioned wheel fork;

[0028] The hub is fitted onto the aforementioned axle;

[0029] The tire is fitted onto the aforementioned wheel hub.

[0030] An aircraft is provided according to a second aspect of this disclosure, comprising:

[0031] The front landing gear as described in any of the above technical solutions;

[0032] Airframe, the aforementioned front landing gear is connected to the aforementioned airframe.

[0033] In one feasible implementation, after the aircraft slides to a preset speed on the ground, the turning servo is de-energized so that when the turning servo reaches the minimum static starting torque, the output shaft of the turning servo can rotate freely.

[0034] Compared to existing technologies, this disclosure offers at least the following advantages: The nose landing gear provided in this embodiment includes a shock absorber strut, a rotating sleeve, a steering servo, a yaw damper, a wheel fork, and a wheel assembly. The shock absorber strut is connected to the aircraft fuselage to support the aircraft. The wheel assembly is rotatably connected to the wheel fork, which in turn is connected to the shock absorber strut. During landing, after the wheel assembly touches the ground, the shock absorber strut absorbs part of the impact force, reducing the load transmitted to the aircraft fuselage during takeoff and landing, thereby reducing the impact on the fuselage. The rotating sleeve is fitted onto the shock absorber strut and can rotate around the axis of the shock absorber strut. The steering servo is fixedly connected to the shock absorber strut and can be connected to the rotating sleeve via a first rocker arm. The steering angle of the nose landing gear can be adjusted via the steering servo. The yaw damper is also fixedly connected to the shock absorber strut and can be connected to the rotating sleeve via a second rocker arm. The damping characteristics of the yaw damper dissipate most of the yaw energy, effectively reducing the load transmitted to the fuselage and improving the strength and stiffness of the front section of the fuselage. This configuration allows the steering servo to be connected to a sway damper in parallel. The steering servo can transmit steering torque through the first rocker arm, while the sway damper can transmit torque through the second rocker arm. The torque transmission paths are relatively independent. During the nose landing gear's steering, the damper can exhibit low-damping characteristics, minimizing interference with the steering torque. This avoids the need to compress the sway damper before steering, which could lead to insufficient response of the nose landing gear when correcting at small angles. In addition, it avoids the steering servo motor having to bear the damping torque generated by the sway damper during sway reduction, reducing damage to the steering servo and extending its service life. Attached Figure Description

[0035] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of exemplary embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this disclosure. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0036] Figure 1 A schematic structural diagram of one angle of the front landing gear according to an embodiment of this disclosure;

[0037] Figure 2 A schematic structural diagram of the front landing gear from another angle, according to one embodiment of the present disclosure;

[0038] Figure 3 This is a schematic structural diagram of a wheel sleeve according to an embodiment of the present disclosure.

[0039] in, Figures 1 to 3 The correspondence between the reference numerals and component names in the attached drawings is as follows:

[0040] 100 Front landing gear, 110 Buffer strut, 120 Swivel, 130 Turning servo, 140 First rocker arm, 150 Damper, 160 Second rocker arm, 170 Wheel fork, 180 Wheel assembly, 181 Axle, 182 Wheel hub, 183 Tire, 190 Torque arm assembly, 191 First torque arm, 192 Second torque arm. Detailed Implementation

[0041] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that the description of these embodiments is intended to aid in understanding the present invention, but does not constitute a limitation thereof. The specific structural and functional details disclosed herein are only for describing exemplary embodiments of the present invention. However, the present invention may be embodied in many alternative forms and should not be construed as being limited to the embodiments described herein.

[0042] like Figures 1 to 3 As shown, a front landing gear 100 is provided according to a first aspect embodiment of the present disclosure, comprising: a buffer strut 110; a rotating sleeve 120 sleeved on the buffer strut 110, the rotating sleeve 120 rotating about the axis of the buffer strut 110; a steering servo 130 fixedly connected to the buffer strut 110, the steering servo 130 being connected to the rotating sleeve 120 via a first rocker arm 140; a yaw damper 150 fixedly connected to the buffer strut 110, the yaw damper 150 being connected to the rotating sleeve 120 via a second rocker arm 160; a wheel fork 170 connected to the buffer strut 110; and a wheel assembly 180 rotatably connected to the wheel fork 170.

[0043] It is understood that the nose landing gear 100 provided in this embodiment includes a buffer strut 110, a swivel 120, a steering servo 130, a yaw damper 150, a wheel fork 170, and a wheel assembly 180. The buffer strut 110 is connected to the aircraft fuselage to support the aircraft. The wheel assembly 180 is rotatably connected to the wheel fork 170, and the wheel fork 170 is connected to the buffer strut 110. During aircraft landing, after the wheel assembly 180 touches the ground, the buffer strut 110 absorbs part of the impact force, thereby reducing the load transmitted to the aircraft fuselage during takeoff and landing, and thus reducing the impact on the aircraft fuselage. A rotating sleeve 120 is fitted onto the buffer strut 110 and can rotate around the axis of the buffer strut 110. A steering servo 130 is fixedly connected to the buffer strut 110 and can be connected to the rotating sleeve 120 via a first rocker arm 140. The steering angle of the nose landing gear 100 can be adjusted via the steering servo 130. A yaw damper 150 is also fixedly connected to the buffer strut 110 and can be connected to the rotating sleeve 120 via a second rocker arm 160. The damping characteristics of the yaw damper 150 dissipate most of the yaw energy, effectively reducing the load transmitted to the fuselage and being more favorable to the strength and rigidity of the front section of the fuselage. Furthermore, this configuration allows the steering servo 130 to be connected in parallel with the damper 150. That is, the steering servo 130 can transmit steering torque through the first rocker arm 140, and the damper 150 can transmit torque through the second rocker arm 160. The torque transmission paths are relatively independent. During the turning process of the front landing gear 100, the damper can exhibit low damping characteristics, with less interference to the turning torque. This avoids the situation where the damper 150 must be compressed first when turning, which would result in the front landing gear 100 not responding sensitively when correcting at small angles. In addition, it avoids the need for the motor of the steering servo 130 to bear the damping torque generated by the damper 150 when the damper 150 is reducing yaw, thus reducing damage to the steering servo 130 and extending its service life.

[0044] It should be noted that during aircraft turning, since the turning servo 130 is connected to the rotating sleeve 120 via the first rocker arm 140, and the yaw damper 150 is connected to the rotating sleeve 120 via the second rocker arm 160, when the turning servo 130 deflects, the output device of the yaw damper 150 will inevitably rotate under the action of the rotating sleeve 120, generating a damping force. However, at this time, the turning speed of the turning servo 130 is low, and the piston rod movement rate of the yaw damper 150 is low. Therefore, the damping torque generated by the yaw damper 150 is small, and its impact on the output torque of the turning servo 130 is small, thus ensuring the accurate steering of the nose landing gear 100 and improving reliability.

[0045] Understandably, compared to the hydraulic steering damping system typically used in the nose landing gear 100 of traditional aircraft, the steering servo 130 can be an electric steering servo 130, thus eliminating the need for an additional hydraulic source, reducing costs and the weight of the airframe and nose landing gear 100, and also reducing the complexity of the overall structure of the nose landing gear 100, reducing maintenance costs, and ensuring economic efficiency.

[0046] Understandably, by setting up the damper 150, the shimmy torque generated by ground shimmy can be prevented from being entirely transmitted to the fuselage through the output shaft of the turning servo 130, thereby consuming the shimmy force and preventing the turning servo 130 from being subjected to repeated alternating loads, which would significantly affect the output accuracy of the turning servo 130 and reduce its service life. Furthermore, it can reduce the strength and rigidity requirements of the front section of the fuselage.

[0047] In some examples, the aforementioned front landing gear 100 further includes a torsion arm assembly 190 disposed between the aforementioned swivel 120 and the aforementioned wheel fork 170.

[0048] Understandably, the nose landing gear 100 may be equipped with a torque arm assembly 190. The torque arm assembly 190 may be positioned between the rotating sleeve 120 and the wheel fork 170 so that the shimmy torque generated at the wheel fork 170 during shimmy of the wheel assembly 180 can be transmitted through the torque arm assembly 190 to the rotating sleeve 120. The rotating sleeve 120 rotates around the axis of the buffer strut 110, and transmits the torque to the steering servo 130 through the first rocker arm 140 and to the shimmy damper 150 through the second rocker arm 160. At this time, the static starting torque of the steering servo 130 and the damping torque generated by the shimmy damper 150 work together to dissipate the shimmy work, reduce the load transmitted to the fuselage, improve the protection of the fuselage, and extend the service life.

[0049] In some examples, such as Figure 1 As shown, the torque arm assembly 190 includes: a first torque arm 191, connected to the rotating sleeve 120 via a first connecting bolt; and a second torque arm 192, connected to the wheel fork 170 via a second connecting bolt. The first torque arm 191 is connected to the second torque arm 192 via a pin. The first torque arm 191 is rotatable around the first connecting bolt, and the second torque arm 192 is rotatable around the second connecting bolt. Both the first torque arm 191 and the second torque arm 192 are rotatable around the pin.

[0050] Understandably, the torque arm assembly 190 may be provided with a first torque arm 191 and a second torque arm 192. The first torque arm 191 is connected to the rotating sleeve 120 via a first connecting bolt, and the first torque arm 191 is rotatable around the first connecting bolt. The second torque arm 192 is connected to the wheel fork 170 via a second connecting bolt, and the second torque arm 192 is rotatable around the second connecting bolt. Furthermore, the first torque arm 191 and the second torque arm 192 can be connected by a pin, and both the first torque arm 191 and the second torque arm 192 can rotate around the pin. This allows the oscillation torque generated at the wheel fork 170 during oscillation of the wheel assembly 180 to be transmitted to the rotating sleeve 120 through the first torque arm 191 and the second torque arm 192. The rotating sleeve 120 rotates around the axis of the buffer support 110, and transmits the torque to the turning servo 130 through the first rocker arm 140, and to the oscillation damper 150 through the second rocker arm 160. At this time, the static starting torque of the turning servo 130 and the damping torque generated by the oscillation damper 150 work together to dissipate the oscillation work, reduce the load transmitted to the fuselage, improve the protection of the fuselage, and extend the service life.

[0051] For example, the pin can be a quick-release pin to improve assembly and disassembly efficiency.

[0052] In some examples, the aforementioned buffer strut 110, the output shaft of the aforementioned steering servo 130, the aforementioned first rocker arm 140, and the aforementioned rotating sleeve 120 together form a four-bar linkage, through which the aforementioned wheel fork 170 is driven when turning.

[0053] It is understandable that a four-bar linkage can be formed from the center of the buffer strut 110 to the output shaft of the steering servo 130, from the output shaft of the steering servo 130 to the first rocker arm 140, and from the first rocker arm 140 to the center of the buffer strut 110 to the connection point of the rotating sleeve 120 and the rocker arm. This allows the wheel fork 170 to be driven by the four-bar linkage, resulting in a direct and reliable transmission. Furthermore, the tilt angle of the wheel fork 170 and the tilt angle of the steering servo 130 are linearly related, making the steering control of the front landing gear 100 simple and reliable.

[0054] In some examples, the aforementioned buffer support 110 includes: a support body, the aforementioned rotating sleeve 120 being fitted onto the aforementioned support body, the aforementioned steering servo 130 and the aforementioned sway damper 150 being fixedly connected to the aforementioned support body; a buffer mechanism being disposed within the aforementioned support body, and the aforementioned wheel fork 170 being connected to the aforementioned buffer mechanism.

[0055] Understandably, the buffer strut 110 can be provided with a strut body and a buffer mechanism. The strut body serves as a support, with one end connected to the aircraft body and the other end having an opening. The buffer mechanism can be housed within the strut body through this opening to save space and is protected by the strut body. The wheel fork 170 is connected to the portion of the buffer mechanism that extends out of the opening. With this configuration, after the wheel assembly 180 lands, the impact on the wheel assembly 180 is transmitted to the wheel fork 170, and then to the buffer mechanism. The buffer mechanism absorbs some of the impact force, reducing the load transmitted to the aircraft body during takeoff and landing, thereby reducing the impact on the aircraft body.

[0056] In some examples, the aforementioned buffer mechanism is a hydropneumatic buffer mechanism, and the aforementioned wheel fork 170 is connected to the piston rod of the aforementioned hydropneumatic buffer mechanism.

[0057] Understandably, the buffer mechanism can be a commercially available, mature hydropneumatic buffer mechanism, depending on the buffering requirements. Specifically, the wheel fork 170 is connected to the piston rod of the hydropneumatic buffer mechanism. When the wheel fork 170 applies pressure to the hydropneumatic buffer mechanism, the piston rod moves upward, causing the high-pressure gas and hydraulic oil inside the hydropneumatic buffer structure to deform and absorb the impact force. After the landing piston rod is compressed to its maximum stroke, the pressure of the high-pressure gas is relatively high, and the piston rod rebounds.

[0058] In some examples, such as Figure 1 As shown, the aforementioned wheel assembly 180 includes: an axle 181 connected to the aforementioned wheel fork 170; a wheel hub 182 fitted onto the aforementioned axle 181; and a tire 183 fitted onto the aforementioned wheel hub 182.

[0059] Understandably, the wheel assembly 180 may be equipped with an axle 181, a hub 182, and a tire 183. The axle 181 is connected to the wheel fork 170, and the hub 182 is fitted onto the axle 181, supporting the tire 183. When the wheel assembly 180 lands, the hub 182 and the tire 183 can rotate synchronously and absorb part of the impact force.

[0060] An aircraft is provided according to a second aspect of the present disclosure, comprising: a nose landing gear 100 as described in any of the above technical solutions; and an airframe, wherein the nose landing gear 100 is connected to the airframe.

[0061] It is understood that the aircraft is equipped with the nose landing gear 100 as described in any of the above technical solutions, and therefore has all the beneficial effects of the nose landing gear 100, which will not be repeated here. The nose landing gear 100 is connected to the fuselage to ensure smooth landing of the aircraft. For example, the aircraft may be an unmanned aerial vehicle (UAV).

[0062] Understandably, when the aircraft needs to correct its course during ground taxiing, the flight control computer issues a command to the steering servo 130. The steering servo 130 transmits torque to the rotating sleeve 120 through the first rocker arm 140. The rotating sleeve 120 then transmits torque to the wheel fork 170 through the first torque arm 191 and the second torque arm 192, thereby achieving the purpose of steering correction.

[0063] In some examples, after the aircraft slides to a preset speed on the ground, the steering servo 130 is de-energized so that when the steering servo 130 reaches the minimum static starting torque, the output shaft of the steering servo 130 can rotate freely.

[0064] Understandably, after the aircraft lands and taxis to a preset speed on the ground, there is no need for steering correction via the tires 183 of the nose landing gear 100. At this time, the steering servo 130 is in a de-energized state, and the output shaft of the steering servo 130 can rotate freely once the minimum static starting torque is reached.

[0065] It should be understood that the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. Although the terms "first," "second," etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another. For example, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit, without departing from the scope of the exemplary embodiments of this utility model.

[0066] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist simultaneously. The term " / and" in this article describes another relationship between related objects, indicating that two relationships can exist. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " in this article generally indicates that the related objects before and after it are in an "or" relationship.

[0067] It should be understood that in the description of this utility model, the terms "upper," "vertical," "inner," "outer," etc., indicate the orientation or positional relationship when the disclosed product is used, or the orientation or positional relationship commonly understood by those skilled in the art. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0068] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0069] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” “containing,” and / or “including” as used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, and do not exclude the presence or addition of one or more other features, quantities, steps, operations, units, components, and / or combinations thereof.

[0070] Specific details are provided in the following description to provide a complete understanding of the exemplary embodiments. However, those skilled in the art will understand that the exemplary embodiments can be implemented without these specific details. In other embodiments, well-known processes, structures, and techniques may be omitted in the depiction of non-essential details to avoid obscuring the exemplary embodiments.

[0071] The above are merely specific embodiments of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

[0072] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art.

Claims

1. A front landing gear characterized by, Comprising: a buffer strut; a rotating sleeve, sleeved on the buffer strut, the rotating sleeve rotating around the axis of the buffer strut; a turning rudder, fixedly connected to the buffer strut, the turning rudder connected to the rotating sleeve through a first rocker arm; a roll damper, fixedly connected to the buffer strut, the roll damper connected to the rotating sleeve through a second rocker arm; a wheel fork, connected to the buffer strut; a wheel assembly, rotationally connected to the wheel fork.

2. The front landing gear according to claim 1, characterized in that, Further comprising: a torsion arm assembly, arranged between the rotating sleeve and the wheel fork.

3. The front landing gear according to claim 2, characterized in that The torsion arm assembly comprises: a first torsion arm, connected to the rotating sleeve through a first connecting bolt; a second torsion arm, connected to the wheel fork through a second connecting bolt; the first torsion arm connected to the second torsion arm through a pin shaft; wherein the first torsion arm can rotate around the first connecting bolt; the second torsion arm can rotate around the second connecting bolt; the first torsion arm and the second torsion arm can both rotate around the pin shaft.

4. The nose landing gear according to claim 3, wherein: the buffer strut, the output shaft of the turning rudder, the first rocker arm and the rotating sleeve jointly form a four-bar linkage mechanism, the wheel fork steering through the four-bar linkage mechanism.

5. The front landing gear of claim 1, wherein, The buffer strut comprises: a strut body, the rotating sleeve sleeved on the strut body, the turning rudder and the roll damper both fixedly connected to the strut body; a buffer mechanism, arranged in the strut body, the wheel fork connected to the buffer mechanism.

6. The nose landing gear according to claim 5, wherein: the buffer mechanism is an oil-gas buffer mechanism, the wheel fork connected to the piston rod of the oil-gas buffer mechanism.

7. The front landing gear of claim 1, wherein, The wheel assembly comprises: a wheel shaft, connected to the wheel fork; a wheel hub, sleeved on the wheel shaft; a tire, sleeved on the wheel hub.

8. An aircraft, characterized in that Comprising: the nose landing gear according to any one of claims 1 to 7; a machine body, the nose landing gear connected to the machine body.

9. The aircraft according to claim 8, wherein: after the aircraft slides on the ground to a preset speed, the turning rudder is in a power-off state, so that the output shaft of the turning rudder can rotate freely when the turning rudder reaches a minimum static starting torque.

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