TETHER ASSEMBLY FOR A RADIO FREQUENCY CONTROLLED AIRCRAFT

Abstract

A tether assembly for a radio-controlled model aircraft, including: a bracket arranged for fixed connection to the radio-controlled model aircraft and including a stop portion; and a bar with a first end pivotably connected to the bracket, and a second end arranged to connect to a flexible wire for a model aircraft anchoring system. Pivoting of the bar in a first rotational direction with respect to the bracket is limited by contact of the bar with the stop portion.

Description

This application is a continuation-in-part patent application under 35 USC 120 of U.S. patent application Ser. No. 13/250,103 filed Sep. 30, 2011, which application is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates generally to a tether assembly for a radio-controlled model aircraft, in particular, a tether assembly for a radio-controlled model helicopter to prevent a guide wire from becoming entangled in the rotor for the helicopter.

BACKGROUND

Radio-controlled model helicopters are relatively difficult to control due to the multiple degrees of freedom of movement possible for the helicopter. Thus, it is difficult for a novice user to learn to fly a model helicopter is an untethered state without causing erratic behavior and uncontrolled movement of the helicopter. In fact, the learning process can result in damage to the helicopter. As a result, it is desirable to provide a more controlled method of learning to fly a model helicopter. However, the prior art fails to teach a means by which movement of the helicopter can be restricted while enabling relative freedom of movement of the helicopter.

SUMMARY

According to aspects illustrated herein, there is provided a tether assembly for a radio-controlled model aircraft, including: a bracket arranged for fixed connection to the radio-controlled model aircraft and including a stop portion; and a bar with a first end pivotably connected to the bracket, and a second end arranged to connect to a flexible wire for a model aircraft anchoring system. Pivoting of the bar in a first rotational direction with respect to the bracket is limited by contact of the bar with the stop portion.

According to aspects illustrated herein, there is provided a radio-controlled model helicopter, including: a fuselage; and a tether assembly including: a bracket fixedly connected to the fuselage and including a stop portion; and a bar with a first end pivotably connected to the bracket, and a second end arranged to connect to a flexible wire for a model aircraft anchoring system. Rotation of the bar in a first rotational direction with respect to the bracket is limited by contact of the bar with the stop surface.

According to aspects illustrated herein, there is provided a method of operating a radio-controlled model helicopter including a fuselage, a rotor located at a top of the helicopter, and a tether assembly with a bracket fixedly connected to the fuselage and with a bar with first end and a second end pivotably connected to the bracket, the bracket including a stop portion, including: connecting the first end to a flexible wire for a model aircraft anchoring system; displacing the helicopter upward, against gravitational force, by rotating the rotor; pivoting the bar, with respect to the bracket, away from the rotor as the helicopter displaces upward; displacing the helicopter downward; pivoting the bar, with respect to the bracket, toward the rotor; contacting the stop portion; and halting movement of the bar toward the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a prospective cut-away view of a radio-controlled model airplane;

FIG. 2 is a representation of reference axes for an aircraft;

FIGS. 3A-C are details of a distal end of a wing for the airplane shown in FIG. 1;

FIG. 4 is a perspective view of a model airplane system;

FIG. 5 is a plan view of the model airplane system of FIG. 4 showing the airplane of FIG. 1 flying at a constant tangent;

FIG. 6 is a perspective view of the model airplane system of FIG. 4 showing the airplane of FIG. 1 flying above the cap of the pylon;

FIG. 7 is a perspective view of the model airplane system of FIG. 4 showing the airplane of FIG. 1 performing a figure 8;

FIG. 8 is a perspective view of a model helicopter with a tether assembly;

FIG. 9 is a perspective bottom view of the tether assembly shown in FIG. 8;

FIG. 10 is a perspective top bottom view of the tether assembly shown in FIG. 8;

FIG. 11 is an exploded view of the tether assembly shown in FIG. 8;

FIG. 12 is a detail of a stop surface for a tether assembly; and,

FIGS. 13A through 13D are pictorial representations of a radio-controlled model helicopter with a tether assembly.

DETAILED DESCRIPTION

At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the invention. While the present invention is described with respect to what is presently considered to be the preferred aspects, it is to be understood that the invention as claimed is not limited to the disclosed aspects.

Furthermore, it is understood that this invention is not limited to the particular methodology, materials and modifications described and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present invention, which is limited only by the appended claims.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. Although any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the preferred methods, devices, and materials are now described.

FIG. 1 is a prospective cut-away view of a radio-controlled model airplane, or aircraft, 100. In the description that follows, the terms airplane and aircraft are used interchangeably. Airplane 100 includes fuselage 102, horizontal stabilizer 104 with controllable rear elevator 106 connected, for example, hingedly connected, to the horizontal stabilizer, and wings 108 and 110 including controllable flaps 112 and 114 connected, for example, hingedly connected, to the first and second wings, respectively. The airplane also includes tail fin 115 and control system 116 including battery 118, and receiver 120 powered by the battery and arranged to receive radio frequency signals from a transmitter (not shown), and computer 124 powered by the battery, electrically connected to the receiver, and arranged to transmit control signals in response to the received radio frequency signals. In an example embodiment, the receiver operates at 2.4 GHz; however, it should be understood that other frequencies are possible. In an example embodiment, the receiver and computer are on single electronic board 125; however, it should be understood that other configurations are possible. Motor 126 is powered by the battery and arranged to receive the transmitted control signals to rotate propeller 128. That is, the propeller provides the force to launch and sustain the airplane in flight according to signals received by the receiver and transmitted by the computer.

Aircraft 100 is not restricted to any particular configuration or shape, except as needed to implement the configurations and functions described below. Receiver 120 and computer 124 can be any receiver and computer known in the art. In an example embodiment, computer 124 is a microprocessor. Motor 126 can be any motor known in the art. Receiver 120 can receive signals from any radio frequency transmitter known in the art. The battery can be any battery known in the art, for example, including, but not limited to, a rechargeable and replaceable LiPO battery of 3.7 volts with a capacity of 150 MAH

In an example embodiment, the airplane includes motor 128 powered by the battery and arranged to receive the transmitted control signals to swivel elevator 106 or flaps 112 and 114. For example, motor 128 is arranged to perform the following operations:

1. Swivel, with respect to a same frame of reference (indicated by arrow 129), flaps 112 and 114 in clockwise direction CD and to swivel the rear elevator in counter clockwise direction CCD; or,

2. Swivel, with respect to the same frame of reference, flaps 112 and 114 in direction CCD and the rear elevator in the direction CD.

Thus, using a single motor 128 and a linkage system described below, computer 124 is able to control flaps 112 and 114 and flaps 106 simultaneously. Motor 128 can be any motor known in the art. In an example embodiment, motor 128 is a servo-motor.

In an example embodiment, the tail fin includes rudder 130 which is fixed with respect to the tail fin. For example, the rudder is in a “zero” position of maximum alignment with the tail fin, or the rudder is at a fixed angle with respect to the tail fin, for example, to maintain tension on the guide wire noted below. In an example embodiment, rudder 130 is displaceable, for example, the rudder is hingedly connected to the tail fin, and the airplane includes motor 132 powered by the battery and arranged to receive the transmitted control signals. Motor 132 is arranged to swivel the rudder in response to the control signals from the computer. Motor 132 can be any motor known in the art. In an example embodiment, motor 132 is a servo-motor. In an example embodiment, the computer is arranged to transmit the control signals to simultaneously control motors 128 and 132.

Airplane 100 includes single flexible wire 134 passing through opening 136 at distal end 138 of one of the wings, for example, the wing pointing inward as the plane traverses a circular path. As shown in the figures, airplane 100 is oriented to fly in a counterclockwise direction (looking down from above the airplane); therefore, opening 136 is located on wing 108. If airplane 100 is oriented to fly in a clockwise direction (looking down from above the airplane); opening 136 is located on wing 110. End 140 of the wire is fastened to point 142 at or near a junction of the fuselage and the wing, for example, wing 108, upon which opening 136 is located. In an example embodiment, the wire passes through an internal space in the wing from opening 136 to point 142. Second end 144 of the wire, not shown in FIG. 1, but shown in FIG. 4 below, is arranged for connection to a point outside of the model airplane. The single flexible wire is used solely to guide the airplane and restrain the airplane to a circular flight path as further described below. However, the flexibility of the wire enables the airplane to fly within the circular flight path as further described below. The wire is not used to transmit power or control signals to the model airplane.

FIG. 2 is a representation of reference axes for aircraft AP. It should be understood that the location of the axes in FIG. 2 is substantially applicable to airplane 100. Longitudinal axis LOA passes through fuselage F of airplane AP, substantially from tail to nose. “Roll” is movement or rotation about LOA. Lateral axis LAA passes through wings W and fuselage F and is perpendicular to LOA. “Pitch” is movement or rotation about LAA. Vertical axis VA passes through F and is perpendicular to LOA and LAA. “Yaw” is movement or rotation about VA. As in known in the art, the exact locations and intersects of the axes depends on the specifics of a particular airplane, for example, the configuration and propulsion system of the airplane.

The following should be viewed in light of FIGS. 1 and 2. Advantageously, the presence of wire 134 and the positioning of opening 136 and point 142 enable desirable stability of airplane 100 while in flight, combined with optimal sensitivity to control commands. In an example embodiment, the location of point 142 is selected through careful analysis of the structure, configuration, and flight characteristics of airplane 100 such that when flaps 112 and 114 are at a position of greatest alignment with wings 108 and 110, respectively, and flaps 106 are at positions of greatest alignment with the horizontal stabilizer, the model airplane is arranged to fly with LOA horizontal. That is, airplane 100 flies in a steady horizontal plane without “pitch.” The respective positions of greatest alignment described above for flaps 112 and 114 and flaps 106 are referred to as “zero positions” in the art. For example, swiveling the flaps out of the zero positions causes some type of pitch. Without the careful placing of point 142 undesirable pitch occurs. For example, if point 142 is too close to nose 146 of airplane 100, the nose pitches downward and if point 142 is too close to tail 148 of airplane 100, the nose pitches upward.

As further described below, wire 134 has a length defining a circular flight path for the model airplane. In an example embodiment, the location of opening 136, in particular with respect to LOA, is selected through careful analysis of the structure, configuration, and flight characteristics of airplane 100 such that when the rudder is in a position of greatest alignment with the tail fin, the model airplane is arranged to fly at a constant tangent with respect to the circular path. That is, airplane 100 flies without undesirable yaw. For example, nose 146 does not point too far inward of the circular path or too far outward of the circular path. The position of greatest alignment described above for the rudder is referred to as “zero position” in the art. For example, swiveling the rudder out of the zero positions causes yaw. Without the careful placing of opening 136 undesirable yaw occurs. For example, if point 142 is too close to nose 146 of the airplane, the nose yaws inward of the flight path and if opening 136 is too close to tail 148 of the airplane, the nose yaws outward of the flight path.

The location of point 142 influences the handling characteristics of airplane 100. For example, is point 142 is too close to nose 146 the response of airplane 100 to control is undesirably sluggish, and if point 142 is too close to tail 148 the response of airplane 100 to control is undesirably sensitive and unstable.

Airplane 100 includes linkage system 150 connecting motors 128 and 132 to flaps 106 and flaps 112 and 114, and the rudder, respectively. In an example embodiment, system 150 includes pushrod 152 connected to motor 128 and control horn 154 in order to actuate the swiveling of flaps 112 and 114. Control horn 154 transmits this motion through pushrod 156 to control horn 158 connected to flaps 106. Thus, the linkage system enables the synchronized motion of flaps 112 and 114 and elevator 106 noted above. Thus, motor 128 provides a linear movement through pushrods 152 and 156 to control horns 154 and 158 in order to move flaps 112 and 114 and elevator 106 in tandem. Therefore, a single motor is used to execute two mechanical commands (flaps 112 and 114 and elevator 106, respectively), eliminating the need for a second motor, which advantageously reduces the weight of aircraft 100. The reduction in weight increases performance, and provides the operator with more precise control of aircraft 100. Via the aerodynamic principle of moving flaps 112 and 114 and elevator 106 in unison and in opposite directions, the aircraft is able to optimally create moment and lift at the same time allowing the operator of the model aircraft to generate sharper turns (corners) and loops which in turn allows for better performance indoors and in smaller space environments.

In an example embodiment, system 150 includes pushrod 160 connected to motor 132 and control horn 162 in order to actuate the swiveling of the rudder. It should be understood that system 150 is not limited to the components and configuration shown and that other components and configurations are possible.

FIGS. 3A-C are details of a distal end of a wing for airplane 100. The presence of the wire in wing 108 or wing 110 also enables desirable flight characteristics and a desirable flight path for airplane 100. The following description is with respect to wing 108; however, it should be understood that the description also is applicable to wing 110. In general, as airplane 100 flies in the circular path noted above and wire 100 is substantially taut, forces exerted by the wire, in particular at distal end 138, urge wing 108 upward or downward such that end 140 of the wire, opening 136, and the other end of the wire are in a straight line, that is, are aligned, as shown in FIG. 3A. If end 138 rolls upward too far, as shown in FIG. 3B, bottom edge 164 of opening 136 contacts the wire and exerts force F1 on the wire so that the ends of the wire are no longer aligned through opening 136. However, the wire reacts to F1 with opposite force F2, pushing end 138 down so that the configuration shown in FIG. 3A is attained. If end 138 rolls downward too far, as shown in FIG. 3C, top edge 166 of opening 136 contacts the wire and exerts force F3 on the wire so that the ends of the wire are no longer aligned through opening 136. However, the wire reacts to F3 with opposite force F4, pushing end 138 up so that the configuration shown in FIG. 3A is attained. Thus, wire 134 provides automatic stabilization with respect to roll about LOA. The operation of wire 134 is further described below.

FIG. 4 is a perspective view of model airplane system 200. Model airplane system 200 includes anchoring system 202 and airplane 100. System 200 is shown with a single airplane 100; however, it should be understood that system is not limited to a single airplane 100 and that a plurality of airplanes 100 can be used in system 200. Further, it should be understood that if a plurality of airplanes 100 are used in system 200, different types of airplanes 100 can be used. By different types of airplanes 100 we mean that the shape and configurations of the airplanes can vary as long as the airplanes include the applicable structure and function described above and below for airplane 100. System 202 includes base 204, pylon 206 fixedly secured to the base, cap 208 at distal end 210 of the pylon, and ring 212 disposed about the pylon, rotatable about the pylon, and displaceable along a length of the pylon. That is, ring 212 fits loosely enough about the pylon such that the ring can rotate around the pylon and be moved up and down along the pylon in direction AD. Base 204 can be a hollow reservoir base to be filled with water, sand or gravel in order to add weight to stabilize the centrifugal force created by the aircraft, and the pylon can be fixed in the middle of the base. The pylon can be made of multiple segments to allow for height adjustment. The ring or rings fit loosely about the pylon to allow the aircrafts to fly around the pylon at variable speeds. Since the rings slide vertically, the rings adapt themselves to the desired altitude of the aircraft as the operator controls the aircraft via flaps 106 and flaps 112 and 114. The cable is thin and flexible and has any desired length in order to fit enclosed indoor spaces or outdoors. The only function of the cable is to tether the aircraft to the ring and pylon.

End 144 of wire 134 is fixedly connected to the ring. The cap prevents the ring from displacing past the distal end, that is, the ring cannot slide over the cap. Any base, pylon, cap, or ring known in the art can be used. It should be understood that other configurations are possible, with the general understanding that a ring is rotatable about and axially displaceable along a fixed element such as a pylon that is securely anchored. As described above, end 140 of the wire is connected to point 142 in airplane 100.

As noted above, the location of point 142 is selected through careful analysis of the structure, configuration, and flight characteristics of airplane 100 such that when flaps 112 and 114 are at a position of greatest alignment with wings 108 and 110, respectively, and elevator 106 are at a position of greatest alignment with the horizontal stabilizer, the model airplane is arranged to fly with LOA horizontal. In portion 214A of the circular flight path, airplane 100 is flying with LOA horizontal.

FIG. 5 is a plan view of system 200 showing airplane 100 flying at a constant tangent. The following should be viewed in light of FIGS. 1 through 5. As noted above, wire 134 has length L defining circular flight path 214 for the model airplane. L is not restricted to any particular value. L can be relatively short, for example, 8 feet, to enable use of system 200 within a room or L can be longer for use of system 200 outdoors. As noted above, the location of opening 136, in particular with respect to LOA, is selected through careful analysis of the structure, configuration, and flight characteristics of airplane 100 such that when the rudder is in a position of greatest alignment with the tail fin, the model airplane is arranged to fly at constant tangent CT with respect to the circular path. That is, angle TA between CT and 214 remains constant and airplane 100 flies without undesirable yaw. The operation of airplane 100 in FIG. 5 can be explained as follows. The airplane flies in direction CCD and force DF acts to keep the airplane moving in direction CCD. Centrifugal force 216 pushes the plane outward and centripetal force 218 pulls the plane inward (with respect to the pylon). The key to the stability and the ability of the airplane to maintain the constant tangent is tension force TF generated by the wire in reaction to the direction force. When point 144 is properly selected, the combination of forces results in the airplane maintaining the constant tangent.

If the guide wire does not pass through the wing and is only attached to the fuselage, undesirable yaw of the nose occurs, for example, inward or outward of the flight path. As a result, the airplane assumes an undesirable orientation, for example, LOA of the airplane crosses the circular flight path (the nose points more toward or more away from a center point for the circular path) rather than being tangential to the circular flight path. If opening 136 is improperly placed undesirable yaw also occurs, for example, if the opening is too close to tail 148 of the airplane, the nose yaws outward of the flight path.

The use of a single flexible guide wire in conjunction with the positioning of the guide wire and the controllability of elevator 106, flaps 112 and 114, and the rudder enable a wide-ranging and complex set of maneuvers for airplane 100. For example, returning to FIG. 4, the airplane is shown performing an internal loop. In this case, elevator 106 and flaps 114 and 114 are swiveled to enable the loop and the guide wire and the positioning of the guide wire enable the airplane to remain stable during the loop.

FIG. 6 is a perspective view of model airplane system 200 showing airplane 100 flying above the cap on the pylon. The use of a single flexible guide wire in conjunction with the positioning of the guide wire and the controllability of elevator 106, flaps 112 and 114, and the rudder also enable the airplane to fly above the cap. This capability increases the vertical maneuvers possible in system 200. Approximate sequential positions of wire 134 in the sequence of FIG. 6 are shown by numerals 134A-E.

FIG. 7 is a perspective view of model airplane system 200 showing airplane of 100 performing a figure 8. Since guide wire 134 is flexible, airplane 100 is able to fly within circular flight path 214. For example, the rudder can be used to move the airplane inward of path 214. Thus, as shown in FIG. 8 a complicated figure 8 pattern, which requires the airplane to fly above the cap, perform loops, and fly inward of path 214 is accomplished. To clarify the view of FIG. 8, the guide wire has not been shown.

Thus, airplane 100 is a totally wirelessly radio controlled tethered model scale airplane able to take off, land, climb, accelerate, dive, perform loops, vertical flight, knife flight, Cuban eight, stalls, inverted flight, flips, regular eight, square loops, and many three dimensional flight maneuvers while the operator is situated remotely outside the flight circumference. The preceding motion occurs within flight paths that are prescribed in an outward direction by flight path 214 and length L of the wire which form a dome-capped right angle cylinder. However, as noted above, for example, as shown in FIG. 8, flight within the cylinder is possible.

In general, the centrifugal force created by the airplane will tend to tense the guide wire as this force urges the airplane away from the pylon. However, through the use of the controllable rudder, the airplane also can fly inside the circumference of the cylinder.

In an example embodiment, the RPM of motor 126 are regulated by electronic speed control (ESC) 154, which is also located in the aircraft, for example, associated with computer 124. This arrangement enables the operator to regulate the speed of the aircraft. To accomplish this control wirelessly, the aircraft used the radio frequency control signals noted above. Computer 124 transmits control signals to the ESC that open or close the throttle of motor 126 to regulate the speed of airplane 100 and converts the radio frequency control signals into an electronic signal in order to command motors 128 and 132 which in turn convert these electronic commands into lineal mechanical commands to actuate elevator 106, flaps 112 and 114, and the rudder.

FIG. 8 is a perspective view of a model helicopter with tether assembly 300.

FIG. 9 is a perspective bottom view of tether assembly 300 shown in FIG. 8.

FIG. 10 is a perspective top view of tether assembly 300 shown in FIG. 8.

FIG. 11 is an exploded view of tether assembly 300 shown in FIG. 8. The following should be viewed in light of FIG. 8 through 11. Tether assembly 300 includes bracket 302 arranged for fixed connection to the radio-controlled model aircraft, for example, model helicopter 304. The assembly also includes stop portion 306 and bar 308 with end 310 pivotably connected to the bracket and end 312 arranged to connect to a flexible wire for a model aircraft anchoring system. As further described below, pivoting of the bar in rotational direction RD1 with respect to the bracket is limited by contact of the bar with the stop portion. Although bar 308 is shown in three portions in FIG. 11, it should be understood that the bar could have more than three portions or fewer than three portions.

In an example embodiment, the bracket includes at least one attachment portion 314 arranged for fixed connection to an aircraft, and side walls 316 and 318 extending from portion 314. The stop portion is disposed between and connected to the walls, and end 310 is disposed between the side walls. In an example embodiment, the stop portion includes stop surface 320 with indent 322 arranged to matingly engage end 310. For example, the curve of the indent matches the curve of the outside surface 324 of the bar.

In an example embodiment, the assembly includes pin 326, end 310 includes slot 328 at least partially formed by distal end 330 of the bar and including opening 332 facing away from the stop portion when the bar is in contact with the stop portion. The pin passes through the slot, and the bar is pivotable about the pin. In an example embodiment, the bar is removable from the bracket by pivoting the bar away from the stop portion, that is, pivoting the bar in direction RD2, opposite RD1, such that opening 332 faces the bracket and the bar can be displaced in direction AD away from the pin.

In an example embodiment, the bracket includes attachment surface 334 arranged to contact an aircraft, and when the bar is in contact with the stop portion, longitudinal axis LA for the bar is about orthogonal to the attachment surface. That is, the bar extends away from a side of the aircraft. In an example embodiment, the attachment portion includes attachment surface 334 arranged to contact the radio-controlled model aircraft, and stop surface 320 is orthogonal to the attachment surface.

FIG. 12 is a detail of a stop surface for a tether assembly. In an example embodiment, stop surface 320 is orthogonal to the side walls, that is, the stop surface is flat instead of curved.

In an example embodiment, radio-controlled model aircraft 304 is a model helicopter including fuselage 336 to which the tether assembly is secured. In an example embodiment, the tether assembly is directly fixedly connected to the fuselage. The helicopter includes landing assembly 338 connected to bottom 340 of the helicopter, and rotatable rotor 342 with blades 343 at top 344 of the helicopter. Direction RD1 is from bottom 340 toward top 344. The rotor includes axis of rotation AR. In an example embodiment, when the bar is in contact with the stop surface, the bar is about orthogonal to the axis of rotation. In general, the stop portion limits movement of the bar toward the rotor, for example, to prevent the flexible line from contacting the rotor/blades. In an example embodiment, the bar has a pivoting range of motion of at least 90 degrees with respect to the bracket. In an example embodiment, the bar has a pivoting range of motion of no more than 90 degrees with respect to the bracket.

FIGS. 13A through 13D are pictorial representations of radio-controlled model helicopter 304 with tether assembly 300. The following should be viewed in light of FIGS. 8 through 13D. The following describes a present invention method for operating a radio-controlled model helicopter. Although the method is presented as a sequence of steps for clarity, no order should be inferred from the sequence unless explicitly stated. An example of the use of a radio-controlled model helicopter with assembly 300 is shown in FIGS. 13A through 13D. In an example embodiment, the radio-controlled model helicopter is helicopter 304 including fuselage 336, rotor 342, and tether assembly 300. A first step connects end 310 to a flexible wire for a model aircraft anchoring system, for example, wire 134 for system 200, as shown in FIG. 13A. In this position, bar 308 can be orthogonal to AR; however, the bar could be rotated further in direction RD2 than shown in FIG. 12A, that is, the bar may not be in contact with surface 320.

A second step displaces the helicopter upward, against gravitational force, by rotating the rotor, as shown in FIG. 13B. A third step pivots the bar, with respect to the bracket, away from the rotor as the helicopter displaces upward, also as shown in FIG. 13B. That is, the bar pivots in direction RD2. In FIG. 13B, the bar has rotated as far as possible in direction RD2. It should be understood that the amount of rotation of the bar in direction RD2 is at least partially a function of the shape of the helicopter and fuselage, which the bar may contact to prevent further rotation in direction RD2. A fourth step displaces the helicopter downward, as shown in FIG. 13C. A fifth step pivots the bar, with respect to the bracket, toward the rotor, that is, in direction RD1, also as shown in FIG. 13C. A sixth step continues to displace the helicopter downward such that bar 308 rotates further in direction RD1 to contact the stop portion with the bar, as shown in FIG. 13D. A seventh step halts movement of the bar toward the rotor, also as shown in FIG. 13D. It should be understood that during the course of operating the helicopter, the orientation of the bar can vary between the positions shown in FIGS. 13A and 13B. For example, the helicopter can rise with the bar in contact with the stop portion.

In general, halting movement of the bar toward the rotor/blades includes halting movement of the flexible wire toward the rotor/blades. Stated otherwise, halting movement of the bar toward the rotor\blades includes preventing the flexible wire from contacting the rotor\blades and becoming entangled with the rotor\blades.

As noted above, learning to fly a radio-controlled model helicopter in an untethered state can be difficult, resulting in frustration for the learner and damage to the helicopter. Advantageously, assembly 300 enables the helicopter to be connected to a tethering system, such as system 200, while ensuring that a tether line or wire, such as wire 134, does not become entangled in the rotor\blades of the helicopter. At the same time, assembly 300 enables a large degree of freedom of movement for the helicopter. For example, the helicopter is able to take off, fly upwards and downwards, and land virtually unhindered by the assembly, as shown in FIGS. 13A through 13D. For example, when the helicopter is connected to wire 134 and system 200, as the helicopter descents, the bar contacts the stop portion, locking any further rotation of the bar toward the rotor. As a result, the bar causes the slip ring to descend in unison with the bar. Without the bar, the helicopter would descend, the slip ring could remain fixed, or descend at a lesser rate, and the wire would contact the rotor\blades.

Thus, it is seen that the objects of the invention are efficiently obtained, although changes and modifications to the invention should be readily apparent to those having ordinary skill in the art, without departing from the spirit or scope of the invention as claimed. Although the invention is described by reference to a specific preferred embodiment, it is clear that variations can be made without departing from the scope or spirit of the invention as claimed.

Claims

1. A tether assembly for a radio-controlled model aircraft, comprising:

a bracket arranged for fixed connection to the radio-controlled model aircraft and including a stop portion; and,

a bar with: a first end pivotably connected to the bracket; and, a second end arranged to connect to a flexible wire for a model aircraft anchoring system, wherein:

pivoting of the bar in a first rotational direction with respect to the bracket is limited by contact of the bar with the stop portion.

2. The tether assembly of claim 1, wherein:

the bracket includes: at least one attachment portion arranged for fixed connection to the radio-controlled model aircraft; and, first and second side walls extending from the at least one attachment portion;

the stop portion is disposed between and connected to the first and second side walls; and,

the first end is disposed between the first and second side walls.

3. The tether assembly of claim 2, wherein:

the first and second side walls are parallel to each other; and,

the stop portion includes a stop surface orthogonal to the first and second side walls.

4. The tether assembly of claim 2, wherein the stop portion includes a stop surface with an indent arranged to matingly engage the first end.

5. The tether assembly of claim 1, further comprising a pin, wherein:

the first end includes a slot at least partially formed by a first distal end of the bar and including an opening facing away from the stop portion when the bar is in contact with the stop portion;

the pin passes through the slot; and,

the bar is pivotable about the pin.

6. The tether assembly of claim 5, wherein the bar is removable from the bracket by pivoting the bar away from the stop portion.

7. The tether assembly of claim 1, wherein:

the bracket includes an attachment surface arranged to contact the radio-controlled model aircraft; and,

when the bar is in contact with the stop portion, a longitudinal axis for the bar is about orthogonal to the attachment surface.

8. The tether assembly of claim 1, wherein:

the attachment portion includes an attachment surface arranged to contact the radio-controlled model aircraft; and,

the stop portion includes a stop surface: arranged to contact the bar; and, orthogonal to the attachment surface.

9. A radio-controlled model helicopter, comprising:

a fuselage; and,

a tether assembly including: a bracket fixedly connected to the fuselage and including a stop portion; and, a bar with: a first end pivotably connected to the bracket; and, a second end arranged to connect to a flexible wire for a model aircraft anchoring system, wherein:

rotation of the bar in a first rotational direction with respect to the bracket is limited by contact of the bar with the stop surface.

10. The radio-controlled model helicopter of claim 9, wherein the tether assembly is directly connected to the fuselage.

11. The radio-controlled model helicopter of claim 9, wherein:

the helicopter includes: a landing assembly connected to a bottom of the helicopter; and, a rotatable rotor at a top of the helicopter; and,

the first rotational direction is from the bottom toward the top.

12. The radio-controlled model helicopter of claim 9, wherein:

the helicopter includes a rotatable rotor at a top of the helicopter;

the rotor includes an axis of rotation; and,

when the bar is in contact with the stop surface, the bar is about orthogonal to the axis of rotation.

13. The radio-controlled model helicopter of claim 9, wherein:

the helicopter includes a rotatable rotor at a top of the helicopter; and,

the stop portion limits movement of the bar toward the rotor.

14. The radio-controlled model helicopter of claim 9, wherein:

the bracket includes: at least one attachment portion arranged for fixed connection to the radio-controlled model aircraft; and, first and second side walls extending from the at least one attachment portion;

the stop surface is disposed between and connected to the first and second side walls; and,

the first end is disposed between the first and second side walls.

15. The radio-controlled model helicopter of claim 9, wherein the bar has a pivoting range of motion of at least 90 degrees with respect to the bracket.

16. The radio-controlled model helicopter of claim 9, wherein the bar has a pivoting range of motion of no more than 90 degrees with respect to the bracket.

17. A method of operating a radio-controlled model helicopter including a fuselage, a rotor located at a top of the helicopter, and a tether assembly with a bracket fixedly connected to the fuselage and with a bar with first end and a second end pivotably connected to the bracket, the bracket including a stop portion, comprising:

connecting the first end to a flexible wire for a model aircraft anchoring system;

displacing the helicopter upward, against gravitational force, by rotating the rotor;

pivoting the bar, with respect to the bracket, away from the rotor as the helicopter displaces upward;

displacing the helicopter downward;

pivoting the bar, with respect to the bracket, toward the rotor;

contacting the stop portion; and,

halting movement of the bar toward the rotor.

18. The method of claim 17 wherein halting movement of the bar toward the rotor includes halting movement of the flexible wire toward the rotor.

19. The method of claim 17 wherein halting movement of the bar toward the rotor includes preventing the flexible wire from contacting the rotor.