Abstract:
A retractable deflector serves to deflect birds and debris from an air intake duct of an aircraft jet engine. The intake duct has a central longitudinal axis and a forward opening for the receipt of air. The deflector includes a plurality of elongate first support members disposed on the air intake duct in spaced relation to each other and having leading ends which extend from a perimeter of said forward opening. These members are mounted for movement to extend and retract the leading ends. A second support member is coupled to the leading ends of these first support members to retain said leading ends in spaced relation. The second support member is extendible in length and configured to hold the leading ends of the first support members sufficiently close together to cause said first support members to deflect at least one of a bird and debris, when in a first, deployed position, and to allow the leading ends of the first support members to maintain a spaced-apart relation along a line which approximately corresponds to the perimeter of the air duct when in a second, retracted position.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The subject matter of this application is related to, and claims priority from, the following provisional applications: 
         [0000]    1) Provisional Application No. 61/205,381 filed Jan. 16, 2009, and
 
2) Provisional Application No. 61/205,785 filed Jan. 22, 2009.
 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Large sized debris which enters the intake of a jet engine may have disastrous consequences, including engine damage, functional engine destruction, and, if all or most engines become non-functional, emergency termination of a flight. This is what occurred on Jan. 15, 2009 with a flight out of LaGuardia Airport which made an emergency landing in the Hudson River after both of its engines failed: The source of damage was a flock of birds some of which entered the air intake of the engines, and rendered both engines non-functional. 
         [0003]    U.S. Pat. No. No. 4,354,346 to Wooding discloses an intake duct for a jet engine which is not retractable. The engine intake extension of the invention is long and expected to be aerodynamically very demanding. 
         [0004]    U.S. Design Pat. No. 433,029 to Eidson comprises an non-retractable cowl. Because it is non-retractable, it will exert aerodynamic inefficiencies throughout a flight. 
         [0005]    U.S. Pat. No. 5,385,612 to Li discloses a cleaning system which is intended to be useful for jet engine intake. However, the device is not retractable, and is not able to provide jet air intake without very substantial aerodynamic limitation. 
         [0006]    U.S. Pat. Nos. 4,137,535; 5,102,375 and 5,139,464 all relate to mechanisms for extending a telescoping antenna. 
         [0007]    The subject matter of these prior U.S. patents is incorporated herein by reference. 
         [0008]    The invention herein discusses methods and apparatus for preventing birds and other debris from doing damage to a jet engine using a deployable/retractable apparatus with acceptable aerodynamic features. 
       SUMMARY OF THE INVENTION 
       [0009]    It is a principal object of the present invention to provide protection to an operating jet engine against airborne birds and other debris which may damage the engine. 
         [0010]    It is a further object of the present invention to provide such protection using retractable apparatus, so that the aerodynamic consequences of such an apparatus are minimized, with respect to duration of use. 
         [0011]    The invention herein discusses methods and apparatus for preventing birds and other debris from damaging a jet engine. It entails the deployment of a radially distributed set of first elements in front of the engine air intake. During the process of deployment, the leading edges of these first elements converge as they are extended from the engine housing. In order to prevent these first elements from suffering damage or mal-positioning due to air turbulence, a second element, oriented transverse to the first elements, and positioned at the leading edge of the first elements, is also deployed. The second element features an adjustable circumference, allowing it to maintain the leading edges during the process of deployment, with the circumference changing as the length of the deployed portion of the first element changes. 
         [0012]    The first elements are retractable into the housing of the engine, so that once the aircraft rises above the altitude where such a strike may occur, better aerodynamic performance may be attained. During the landing phase of the flight, the first elements may be re-deployed when the aircraft has descended to an altitude where such protection is need. The 
         [0013]    There are a variety of possible first element configurations involving variations in (a) the shape of the first element (straight and curved), (b) the number of first elements, and (c) the structural details of the first elements (for example: rigid rod terminating in eyelet, rigid rod terminating in tubular structure, hollow rod terminating in T-shaped tubular structure, and cable terminating in eyelet). 
         [0014]    There are a variety of possible second element configurations involving variations in (a) the quality of the second element material (elastic, spring, cable), and (b) the number of second elements. 
         [0015]    In one preferred embodiment of the invention, electromagnetic coupling secures adjacent leading edges of first elements in the fully deployed state. 
         [0016]    In another preferred embodiment, de-icing apparatus warms the first and/or second elements. 
         [0017]    In yet another preferred embodiment, the entire deflector apparatus rotates about the longitudinal axis, to provide additional protection. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1A  is a perspective view of a jet engine with a deployed deflector apparatus having multiple curved first elements and a single transverse second element. 
           [0019]      FIG. 1B  is a perspective view of a jet engine with a deployed deflector apparatus having multiple straight first elements and a single transverse second element. 
           [0020]      FIG. 1C  is a representational diagram of a jet engine indicating the storage of retracted first elements and a retracted second element. 
           [0021]      FIG. 1D  is a representational diagram of a jet engine indicating the storage of telescoping first elements. 
           [0022]      FIG. 1E  is a front view of the placement of first elements within an engine housing. 
           [0023]      FIG. 2A  is a representational diagram showing a front view of a fully deployed deflector apparatus with 16 first elements arrayed in a radially symmetric configuration, and a second element. 
           [0024]      FIG. 2B  is a representational diagram showing a front view of a partially deployed deflector apparatus with 16 first elements arrayed in a radially symmetric configuration, and a second element. 
           [0025]      FIG. 2C  is a representational diagram showing another front view of a partially deployed deflector apparatus with 16 first elements arrayed in a radially symmetric configuration, and a second element, showing a lesser degree of deployment than that shown in  FIG. 2B . 
           [0026]      FIG. 2D  is a representational diagram showing another front view of a partially deployed deflector apparatus with 16 first elements arrayed in a radially symmetric configuration, and a second element, showing a lesser degree of deployment than that shown in  FIG. 2C . 
           [0027]      FIG. 2E  is a representational diagram showing a front view of the deflector apparatus of  FIG. 2D  in a fully retracted state. 
           [0028]      FIG. 3A  shows a representational cross sectional diagram of a deflector apparatus with curved, telescoping first elements, and a second element, in a deployed position. 
           [0029]      FIG. 3B  shows a representational cross sectional diagram of a deflector apparatus with curved, telescoping first elements, and a second element, in a retracted position. 
           [0030]      FIG. 4A  shows a representational cross sectional diagram of a deflector apparatus with straight, telescoping first elements, and a second element, in a deployed position. 
           [0031]      FIG. 4B  shows a representational cross sectional diagram of a deflector apparatus with straight, telescoping first elements, and a second element, in a retracted position. 
           [0032]      FIG. 5A  shows a representation diagram of a deflector apparatus with four first elements, a second cable element, and a single winch for adjusting the length of the cable. 
           [0033]      FIG. 5B  shows a representation diagram of a deflector apparatus with four first elements, two second cable elements, and two winches for adjusting the length of the cables. 
           [0034]      FIG. 5C  shows a representation diagram of a deflector apparatus with four first elements, four second cable elements, and four winches for adjusting the length of the cables. 
           [0035]      FIG. 5D  shows a representational diagram of a T-shaped leading end of a first element, showing apparatus to decrease the friction due to motion of a cable. 
           [0036]      FIG. 6A  is a representational diagram showing a coiled second element, in a configuration corresponding to a fully deployed state. 
           [0037]      FIG. 6B  is a representational diagram showing a coiled second element, in a configuration corresponding to a partially deployed state. 
           [0038]      FIG. 6C  is a representational diagram showing a coiled second element, in a configuration corresponding to a partially deployed state, showing a lesser degree of deployment than that of  FIG. 6B . 
           [0039]      FIG. 6D  is a representational diagram showing a coiled second element, in a configuration corresponding to a partially deployed state, showing a lesser degree of deployment than that of  FIG. 6C . 
           [0040]      FIG. 6E  is a representational diagram showing a coiled second element, in a configuration corresponding to a fully retracted state. 
           [0041]      FIG. 7A  is a representational diagram showing a coiled second element passing through the leading edge of each of two T-shaped first elements, in a deployed configuration. 
           [0042]      FIG. 7B  is a representational diagram showing a coiled second element passing through the leading edge of each of two T-shaped first elements, in a retracted configuration. 
           [0043]      FIG. 8A  is a perspective view of a jet engine with a deployed deflector apparatus having multiple curved first elements and two transverse second elements. 
           [0044]      FIG. 8B  is a perspective view of a jet engine with a deployed deflector apparatus having multiple straight first elements and two transverse second elements. 
           [0045]      FIG. 8C  is a representational diagram of a jet engine indicating the storage of retracted first elements and two retracted second elements. 
           [0046]      FIG. 9A  is a representational diagram showing a front view of a fully deployed deflector apparatus with 16 first elements arrayed in a radially symmetric configuration, and two second elements. 
           [0047]      FIG. 9B  is a representational diagram showing a front view of a partially deployed deflector apparatus with 16 first elements arrayed in a radially symmetric configuration, and two second elements. 
           [0048]      FIG. 9C  is a representational diagram showing another front view of a partially deployed deflector apparatus with 16 first elements arrayed in a radially symmetric configuration, and two second elements, showing a lesser degree of deployment than that shown in  FIG. 9B . 
           [0049]      FIG. 9D  is a representational diagram showing another front view of a partially deployed deflector apparatus with 16 first elements arrayed in a radially symmetric configuration, and two second elements, showing a lesser degree of deployment than that shown in  FIG. 9C . 
           [0050]      FIG. 9E  is a representational diagram showing a front view of the deflector apparatus of  FIG. 9D  in a fully retracted state. 
           [0051]      FIG. 10A  is a representational diagram showing a cross sectional view of a tubular T-shaped first element, with projections forming two pairs of second elements, containing cables. 
           [0052]      FIG. 10B  shows a representation diagram of a deflector apparatus with four first elements, four second cable elements each located at the leading edge of the first elements, four additional second cable elements each located between the leading edge and the trailing edge of the first elements, and four winches for adjusting the length of the additional cables elements. 
           [0053]      FIG. 10C  is a representational diagram of a jet engine indicating the storage of retracted first elements and two retracted second elements. 
           [0054]      FIG. 11A  is a perspective view of a jet engine with a deployed deflector apparatus having multiple curved first elements and six transverse second elements. 
           [0055]      FIG. 11B  is a perspective view of a jet engine with a deployed deflector apparatus having multiple straight first elements and six transverse second elements. 
           [0056]      FIG. 12A  is a representational diagram showing a front view of a fully deployed deflector apparatus with 16 first elements arrayed in a radially symmetric configuration, and six second elements. 
           [0057]      FIG. 12B  is a representational diagram showing a front view of a partially deployed deflector apparatus with 16 first elements arrayed in a radially symmetric configuration, and six second elements. 
           [0058]      FIG. 12C  is a representational diagram showing another front view of a partially deployed deflector apparatus with 16 first elements arrayed in a radially symmetric configuration, and six second elements, showing a lesser degree of deployment than that shown in  FIG. 12B . 
           [0059]      FIG. 12D  is a representational diagram showing another front view of a partially deployed deflector apparatus with 16 first elements arrayed in a radially symmetric configuration, and six second elements, showing a lesser degree of deployment than that shown in  FIG. 12C . 
           [0060]      FIG. 12E  is a representational diagram showing a front view of the deflector apparatus of  FIG. 12D  in a fully retracted state. 
           [0061]      FIG. 13  is a representational diagram of a deflector apparatus with 40 T-shaped first elements in a fully deployed configuration. 
           [0062]      FIG. 14  is a representational diagram of two T-shaped first elements with electromagnetic apparatus at two adjacent projections. 
           [0063]      FIG. 15A  is a representation diagram of a deflector apparatus with four cable-based first elements, four winches for adjusting the length of the respective cables, and a cable-based second element associated with a tubular T-shaped additional first element and with an additional associated winch. 
           [0064]      FIG. 15B  is a perspective view of a jet engine with a deployed deflector having the apparatus shown in  FIG. 15A . 
           [0065]      FIG. 16A  is a cross sectional view of a portion of a hinge and a hinge-controlling apparatus for attaching a first element to a jet engine, showing a deployed state of the first element. 
           [0066]      FIG. 16B  is a cross sectional view of the hinge and hinge-controlling apparatus of  FIG. 16A , showing a transitional state between the deployed state and the retracted state. 
           [0067]      FIG. 16C  is a cross sectional view of the hinge and hinge-controlling apparatus of  FIG. 16B , showing the retracted state. 
           [0068]      FIG. 17  is a perspective view of a jet engine with a deployed deflector apparatus having multiple straight first elements and a single transverse second element, with the deflector apparatus showing rotational motion about the longitudinal axis of the engine. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0069]      FIGS. 1A and 1B  show two types of deflector apparatus for a jet engine.  FIG. 1A  shows  12  curved first elements  102  projecting from the air intake end of jet engine  100 .  FIG. 1B  shows  11  straight first elements  104  projecting from the air intake end of jet engine  101 . Many other configurations are possible. Both figures show first elements in a radially symmetric distribution. Configurations with a greater or lesser number of first elements are possible. 
         [0070]    To stabilize the first elements during deployment, a second expandable element connects the leading end of the first elements, shown as  103  in  FIG. 1A and 105  in  FIG. 1B . 
         [0071]    Embodiments of the invention in which the first elements link at a point or a small area without an aperture (i.e. an opening at the most forward point) are possible. Embodiments of the invention in which the circular apparatus is substituted by an apparatus of another shape are possible. Elliptical shapes, hexagonal shapes, octagonal shapes, polygonal shapes (and any shape in which the number of sides to the central aperture is equal to the number of first elements) are possible. A shape which is identical to that of the engine housing, if not circular, is possible. 
         [0072]      FIG. 1C  shows the first elements  108  in the fully retracted position (indicated in the figure as broken lines) within the housing of engine  106 . In the embodiment shown in  FIG. 1C , the first elements in the retracted state are stored inside the engine housing, and are not telescoped. The configuration shown in  FIG. 1C  would be suitable for straight first elements, and could also be used for curved first elements with a large radius of curvature. Curved first elements with a smaller radius of curvature (i.e. approximately the same radius of curvature as the engine housing) could be stored by rotating them 90 degrees so that they would, in the stored state, lie along the circumference of the engine. 
         [0073]      FIG. 1D  shows the storage of telescoped first elements  110 . The advantage of telescoping is ease of storage in the retracted state. The telescoped configuration for the retracted state shown in  FIG. 1D  could also accommodate curved first elements (e.g. as shown in  FIGS. 3A and 3B ) with a smaller radius of curvature (without having to rotate 90 degrees for storage) than that of the engine housing of  FIG. 1C . 
         [0074]      FIG. 1E  shows a front view of telescoped first elements  114  within compartments  112 , situated in engine housing  118 . The engine apparatus is situated centrally, in the location indicated by  116 . 
         [0075]      FIGS. 2A through 2E  show front views of an engine with the first elements joined at the leading edge by a circular second element. During the deflector retraction process, the circular second element increases in circumference as shown in the sequence of  FIGS. 2A to 2E .  FIG. 2E  shows the fully retracted state—where most or all of the first element apparatus has been withdrawn into the engine housing, as the radius of what was the central circular element is increased to the point that it equals approximately that of the engine housing. A 16 first element configuration is shown; configurations with fewer and larger numbers of first elements are possible. 
         [0076]      FIGS. 3 and 4  show a side view of an embodiment of the apparatus, emphasizing a first element structure with a telescoping configuration.  FIGS. 3  shows an apparatus with curved first elements, and  FIGS. 4  shows an apparatus with straight first elements. Each figure shows that the first element structure consists of a series of cylindrical elements with a telescoping structure, much like a retractable automobile antenna.  FIG. 3A  shows the first elements  300 A fully extended, with circular stabilizing apparatus  310 A assuming a minimal circumference. In the fully retracted state shown in  FIG. 3B , the telescoping of concentric cylindrical first elements  300 B allows the first elements to fit inside the engine housing, while the circular apparatus  310 B expands (in a process described hereinbelow) so that it may also fit into the engine housing. Only two sets of first elements are shown for simplicity. Configurations with more sets of first elements are desirable to allow for greater stability and ease of retraction. Arrows above  FIGS. 3A and 3B  show the direction of air flow into the engine. Electrically controllable telescoping elements which are controlled by one or more electric motors, by hydraulic apparatus and by pneumatic apparatus are known. 
         [0077]      FIG. 4A  shows the first elements  400 A fully extended, with circular stabilizing apparatus  410 A assuming a minimal circumference. In the fully retracted state shown in  FIG. 4B , the telescoping of concentric cylindrical first elements  400 B allows the first elements to fit inside the engine housing, while the circular apparatus  410 B expands (in a process described hereinbelow) so that it may also fit into the engine housing. Only two sets of first elements are shown for simplicity. Configurations with more sets of first elements are desirable to allow for greater stability and ease of retraction. Arrows above  FIGS. 4A and 4B  show the direction of air flow into the engine. 
         [0078]      FIGS. 5A-5C  show a possible structure for controlling the configuration of the second element. Apparatus with only four first elements is shown for ease of interpretation. Referring to  FIG. 5A , as first elements  510 A-D are retracted (by movement which is radially outward in the figure), cable  512 , the second element, is gradually unspooled from spool  518  by motorized apparatus  516  in housing  514 . (The segment of cable which lies between each of  510 A/B,  510 B/C,  510 C/D and  510 D/A is shown in a curved configuration, which would be the conceptual limiting case with an infinite number of first elements; In the case of a large number of first elements, a many-sided polygon would approximate the circle shown in the figure.) As shown in the figure, the terminal segment of each radial arm forms a curved cylindrical shape which allows the cable to pass through. When the first elements go from the retracted state to the deployed state, motor  516  causes cylinder  518  to take up cable slack as it becomes available. Embodiments of the invention in which  512  is a spring apparatus (see hereinbelow) are possible. 
         [0079]      FIG. 5B  shows an apparatus similar to that of  5 A, except that there are two cables,  542 A and  542 B. The slack for one end of each of  542 A and  542 B is controlled by slack uptake and release apparatus  544 A and  544 B (each of which operate in similar fashion to that of  514 ). 
         [0080]      FIG. 5C  shows an apparatus similar to that of  FIGS. 5A and 5B  except that there is one cable segment ( 572 A-D) for each pair of adjacent retractable arms, and one slack uptake and release apparatus ( 574 A-D) for one end of each pair of adjacent cable ends. For example, when the apparatus in  FIG. 5C  goes from the deployed to the retracted state: 
         [0000]      574 A unrolls appropriate portions of one end of cable  572 A and one end of cable  572 B;
   574 B unrolls appropriate portions of one end of cable  572 B and one end of cable  572 C;
   574 C unrolls appropriate portions of one end of cable  572 C and one end of cable  572 D; and
   574 D unrolls appropriate portions of one end of cable  572 D and one end of cable  572 A.
 
         [0081]    Configurations of the invention with various friction reducing elements are possible.  FIG. 5D  shows a representational cross sectional view of the terminal protuberance of a first element in one embodiment of the invention. In order to minimize friction between the cable and the first element, one or more of friction reducing elements  592 A,  592 B,  594 A,  594 B,  596 A,  596 B,  598 A, and  598 B are included. These may be flat rolling elements, or grooved wheels. In another embodiment of the invention,  592 A and B may be considered to be a cross-sectional representation of a circular bearing device which guides the cable with minimal friction; the same is true of the  594 A and B pair, the  596 A and B pair and the  598 A and B pair. Embodiments of the invention with either a greater or lesser number of guiding elements are possible. Embodiments of the invention in which the friction-reducing elements are actively lubricated, or are self-lubricating are possible. Many other friction reducing configurations will be apparent to those skilled in the art. 
         [0082]      FIGS. 6A to 6E , shows a circular spring apparatus which provides the attractive force between adjacent distal ends of the first elements when they are deployed.  FIGS. 6A to 6E  correspond, respectively to the states of deployment/retraction shown in  FIGS. 2A to 2E , i.e. five states ranging from first elements fully deployed ( FIG. 6A ) to first elements fully retracted ( FIG. 6E ). 
         [0083]      FIG. 7 , consisting of  FIGS. 7A and 7B  shows the circular spring apparatus of  FIG. 6  in conjunction with first elements in two different states of retraction/deployment: 
         [0084]      FIG. 7A  corresponds to  FIGS. 2B and 6B ; while 
         [0085]      FIG. 7B  corresponds to  FIGS. 2D and 6D . 
         [0086]    Embodiments of the spring apparatus shown in  FIGS. 6 and 7  in which one end of the spring is anchored to a first element are possible. 
         [0087]      FIGS. 8A and 8B  (analogous to  FIGS. 1A and 1B  respectively) show a configuration of the apparatus in which there are two transverse/second element supporting apparatus structures ( 810  and  820  for engine  815  in  FIG. 8A , and  830  and  840  for engine  835  in  FIG. 8B ). The mode of operation of the transverse apparatus shown in each of the two figures is similar to that of the configurations with one transverse supporting apparatus, i.e. in the case of two such apparatus, each is retractable as shown by  850  and  860  in  FIG. 8C . In  FIG. 8C , the engine is indicated by  855  and the first support elements are indicated by broken lines  870 . 
         [0088]      FIGS. 9A-E  (each showing two circular second elements) are analogous to  FIGS. 2A-E  (each showing one circular second element). As indicated hereinabove, in many configurations the circle representing the second element in the figure represents the theoretical upper limit of a many-sided polygon. 
         [0089]    In  FIG. 9A , the fully deployed configuration, the distal (i.e. nearest to the leading end) circular apparatus is  910 A and the proximal (i.e. nearest to the trailing edge) one is  920 A. In  FIG. 9B , the partially retracted configuration, the distal circular apparatus is  930 B and the proximal one is  940 B. In  FIGS. 9C-E , the proximal circular apparatus is retracted within the engine housing, so the appearance is identical to  FIGS. 2C-2E , respectively. 
         [0090]      FIG. 10A  shows a representational view of a complex first element for a configuration with one distal transverse supporting apparatus and one transverse supporting apparatus in the mid-portion of the first element. In principle, such a complex element has features of both a first element (i.e. as it exits the engine housing, one section extends longitudinally) and a second element (has projections which, as they exit the housing, extend in a direction transverse to the longitudinal section). The entire apparatus of  FIG. 10A  is analogous to element  510 A in  FIG. 5A  (which is a first element without a transverse supporting apparatus in its midportion). Referring again to  FIG. 10A , cables  1000 A and  1000 B help to align and hold together the distal ends of the complex first elements; They are analogous to any of [a]  512  in  FIG. 5A ; [b]  542 A and  542 B in  FIG. 5B ; and [c] any of (i)  572 A and  572 B, (ii)  572 B and  572 C, (iii)  572 C and  572 D. and (iv)  572 D and  572 A in  FIG. 5C . In addition, cables  1000 C and  1000 D serve to anchor the midportion of each complex first element. 
         [0091]    When the apparatus in  FIG. 10A  is utilized in a configuration analogous to that of  FIG. 5C  (i.e. an array of four of complex first element  1002 ), each cable segment analogous to  1000 C in  FIG. 10A  extends to the neighboring first element to the left (see  FIG. 10B ), enters its main shaft, and comprises the segment analogous to  1000 D in that left neighboring first element. Similarly, each cable segment analogous to  1000 D in  FIG. 10A  extends to the neighboring first element to the right (see  FIG. 10B ), enters its main shaft, and comprises the segment analogous to  1000 C in that right neighboring first element. 
         [0092]    In a configuration analogous to that of  FIG. 5A , the cable segment  1000 C would extend from shaft  1002 , out through projection  1004 , and thence through the midportion of each first element (via projections analogous to each of  1004  and  1006 ), and ultimately return to first complex element  1002  via projection  1006  to form cable segment  1000 D. 
         [0093]    In configurations analogous to that shown in  FIG. 5B , the cable segment  1000 C would extend from shaft  1002 , out through projection  1004 , through the midportions of two or more adjacent first elements, each first element (via projections analogous to each of  1004  and  1006 ), and ultimately enter another first element via a projection analogous to  1006 , and form a cable segment analogous to segment  1000 D in another first element. 
         [0094]    In configurations analogous to that of  FIG. 5B , the cables within first elements traversed by transverse cable segment must be geometrically set up so that the transverse segment does not contact longitudinal segments analogous to  1000 A and  1000 B. Although  FIG. 10A  shows all four cable segments lying in the same plane (i.e. the plane of the figure), in three dimensions, the transverse segment could cross through the shaft either so that it does not contact either of the segments analogous to  1000 A or  1000 B (i.e. by crossing above or below the plane defined by  1000 A and  1000 B). 
         [0095]    The advantage of projections  1004  and  1006  is that they help guide and secure the transverse cable in the midportion of the first element, and allow for a locking mechanism to further stabilize the apparatus. The disadvantage is that they add weight, they further restrict the open area in front of the engine, and they make retraction of the first element more complex. Embodiments of the invention in which each of projections  1004  and  1006  are absent, replaced by respective openings in the shaft of  1002  to accommodate respective cables  1000 C and  1000 D are possible. 
         [0096]    Though  FIG. 10A  shows projections  1004  and  1006  to be in the midportion of the first element, configurations are possible in which the junction is asymmetrically located, either proximally (i.e. nearer to the engine housing) or nearer to the distal end of the apparatus. 
         [0097]    The proximal ends of each of  1000 C and  1000 D are linked to cable control apparatus which appropriately releases or takes in cable, as the situation may require. Such cable control apparatus is analogous to any of [a]  514 ,  516  and  518  shown in  FIG. 5A ; [b]  544 A and  544 B shown in  FIG. 5B ; and [c]  574 A,  574 B,  574 C and  574 D shown in  FIG. 5C . 
         [0098]    Cables may be secured within  1002  by a variety of means and mechanisms including: 
         [0000]    a) situating the cable within a non-moving sheath;
 
b) grooves within  1002  for each cable; and/or
 
c) one or more guiding wheels, rollers, or bearings along the length of the cable within  1001 ,  1002 ,  1003 ,  1004  and/or  1006 , analogous to that which is shown herein in conjunction with  FIG. 5D .
 
         [0099]      FIG. 10B  shows a deflector which includes an array of four of the complex first elements shown in  FIG. 10A . The apparatus shown in the figure is analogous to that shown in  FIG. 5C . However, the apparatus in  FIG. 10B  includes an additional transverse support group of structures. Cable take-up apparatus  1008  controls the length of cable segment  1000 D, which passes through  1002 , exits through projection  1006  and enters the corresponding structure on the right side of the figure. Similarly, cable take-up apparatus  1008  controls the length of cable segment  1000 C, which passes through  1002 , exits through projection  1004  and enters the corresponding structure on the left side of the figure. The operation of  1008  and associated components is similar to that of  574 A-D in  FIG. 5C . These aforementioned structures link the midsection (which need not be located at the geometric middle) of the complex first elements (e.g.  1002 ). 
         [0100]    The cable segments which forms the distal second element exit through projection  1003  as  1000 B, and then enters the corresponding structure indicated by elements on the right side of the figure; Another cable segment which forms the distal second element exit through projection  1001  as  1000 A, and then enters the corresponding structure indicated by elements on the left side of the figure. 
         [0101]    The four cable take-up apparatus for the distal second elements is not shown in the figure, but is similar to that of  1008 , and  574 A-D. Long broken lines in the figure indicate cable for the distal/ leading edge second elements which are contained within  1002 . Although these cable segments extend into the proximal shaft of  1002  (as shown in  FIG. 10A ), these segments of cable are not shown in the figure, for clarity. Short broken lines indicate cable for the proximal/ midportion second elements, which are shown in their full extent. 
         [0102]      FIG. 10C , analogous to  FIG. 1D , shows a representational view of the retracted state, of an embodiment with (a) one transverse stabilizing cable  1020  in its midportion, and (b) collapsible/telescoping first elements  1022 . With embodiments of the invention with lateral protuberances in the midsection, there will be a limitation to the collapse above and below such midsection protuberances. An embodiment of the invention is also possible in which the midsection protuberances themselves are able to collapse/telescope. 
         [0103]    The telescoped configuration for the retracted state shown in  FIG. 10C  could also accommodate curved first elements (e.g. as shown in  FIGS. 3A and 3B ), as discussed hereinabove in conjunction with  FIG. 1D . 
         [0104]    Whereas the aforementioned embodiments contain either no transverse elements along the first elements, or one such element ( FIGS. 8A to 9E ),  FIG. 11A  shows a configuration with  5  transverse elements and curved first elements (analogous to  FIGS. 1A and 8A ) and  FIG. 11B  shows a configuration with 5 transverse elements and straight first elements (analogous to  FIGS. 1B and 8B ). Configurations with greater and lesser numbers of first elements are possible. More first elements result in a greater degree of first element stability and the ability to limit the maximum size of an object which may cross the barrier resulting from the deployment of the apparatus described herein. On the other hand, more first elements result in greater weight, greater resistance to air entry and more complex cable arrangements within first elements and more complex cable supporting apparatus. 
         [0105]    FIGS.  12 A-E—analogous to  FIGS. 2A-E  and  9 A-E—show a front view of some of the successive steps in the transition from a fully deployed apparatus ( FIG. 12A ) to a fully retracted one ( FIG. 12E ) for a configuration with five transverse elements,  1200 ,  1202 ,  1204 ,  1206  and  1208  (in addition to the distal transverse support common to all of the configurations hereinabove).  FIG. 12B  shows a state in which two of the five transverse elements have been retracted (and in which the non-retracted transverse elements and the distal supporting apparatus have each (i) been pulled back and (ii) undergone an increase in radius).  FIG. 12C  shows a state in which four of the five transverse elements have been retracted (and in which the one remaining non-retracted transverse element and the distal supporting apparatus have each (i) been further pulled back and (ii) undergone a further increase in radius).  FIG. 12D  shows a state in which all of the five transverse elements have been retracted (and in which the remaining non-retracted distal supporting apparatus has (i) been still further pulled back and (ii) undergone a still further increase in radius). 
         [0106]      FIG. 13  shows a front view of a fully deployed engine protection device with  40  first elements ( 1300 A), in which first element has a terminal protuberance ( 1300 B) which is analogous to  1001  and  1003  of  FIG. 10A  herein. Cable or cables  1302 , analogous to the cable shown in any of the configurations of  FIGS. 5A ,  5 B and  5 C, serve to draw the protuberances together as the device is deployed, and to stabilize the protuberances as the device is retracted. In addition  1302  may secure each of the 40 protuberances  1300 B so that they are in secure contact with each other. Another mechanism for securing each  1300 B to its two adjacent neighboring  1300 Bs is to have the surface of each form a secure fit with its neighboring  1300 B, either because the surfaces are parallel, or because the surfaces have complementary extensions and depressions which promote such a fit. Furthermore, by making the projections and depressions cone-shaped rather than cylindrical, a non-perfect alignment of adjacent first elements during deployment may be corrected for. 
         [0107]    In another embodiment of the invention, a magnetic attraction between adjacent protuberances may be used to promote their attraction during deployment. The magnetic mechanism may be from fixed elements (e.g. one side of each protuberance is a north magnetic pole, and the other side is a south pole, such that the arrangement is: 
         [0000]      . . . (N-S)-(N-S)-(N-S)-(N-S) . . . 
         [0108]    Alternatively, the source of magnetism may be electromagnetic, as shown in  FIG. 14 , thereby allowing for a simple means of turning off the attractive mechanism.  FIG. 14  shows a coil of conducting wire  1404 A on one end of first element  1400 A for generating a magnetic field when a current is passed through it. The wires need not be on the surface of the object, and may be embedded beneath the surface. The ends of the coil  1404 B pass through the shaft of  1400 A to a power supply and control unit. There is corresponding apparatus  1406 A on the end of first element  1402 A for generating a magnetic field when a current is passed through it. The ends of the coil  1406 B pass through the shaft of  1402 A to a power supply and control unit. The orientation and winding of the coils is such that  1404 A attracts  1406 A when a current is passed through each. In a preferred embodiment, additional coils are placed symmetrically on each projection, i.e.  1400 B and  1402 B, to allow for the attraction to each of their respective neighboring projections. 
         [0109]    In yet another embodiment of the invention, an active locking mechanism between adjacent protuberances is possible. Activation and deactivation of the locking mechanism may be electric or via one or more cables which traverse one or more of first elements with such a mechanism. 
         [0110]      FIG. 15A  shows an embodiment of the invention in which the first elements are not composed of rigid rods. These first elements consist of cables  1502 A-D. At their respective proximal ends are cable take-up and release apparatus  1500 A-D; At their respective distal ends is an eyelet  1504 A-D, which allows each of  1502 A-D to be pulled during the deployment process. Deployment is caused when cable take-up  1506  winds in  1510 , causing the perimeter of this cable loop to decrease. As the decrease occurs cables  1502 A-D are pulled out of  1500 A-D. The tension on the loop  1510  exerted by each of  1500 A-D is adjusted to keep loop  1510  centered over the air intake. In one version of this embodiment of the invention, an apparatus  1520  (either electromechanical, hydraulic or pneumatic) pushes  1508  distally (toward the center of the air intake) during deployment. The retraction of the deflector involves active uptake of cables  1502 A-D by take-up apparatus  1500 A-D, with simultaneous spooling out of cable from  1506 . In the version which includes  1520 , it may be used to facilitate the retraction of  1508 . The tension of each of  1500 A-D on each respective one of  1502 A-D is adjusted, during the retraction process, to keep the deflector properly centered at all times. 
         [0111]      FIG. 15B  shows a perspective view of a jet engine  1530 , and the first elements and second elements (with element numbers corresponding to those of  FIG. 15A ) which make up this embodiment. The embodiment shown in the figure contains no rigid support elements except for  1508 . It would therefore be situated at the mouth of the engine. 
         [0112]    Versions of this embodiment with two or more sets of apparatus to shorten loop  1510  are possible. Versions are also possible in which each of  1502 A-D is a rigid telescoping rod, anchored to the engine housing, and deployed by the force exerted by cable take-up device  1506 . 
         [0113]      FIGS. 16A-C  show an embodiment of a hinge which anchors a first element  1600  to the engine housing, and is retractable. The first element is joined to one hinge component  1602 , and retraction rod  1608  is joined to the other hinge component  1606 .  1602  and  1606  pivot about  1604 .  1608  is moved in and out by apparatus  1610 , either mechanically or electromagnetically.  1608  is anchored to inner housing wall  1612  (anchoring not shown in figure), which is contiguous with  1614  which is the support apparatus for the engine. 
         [0114]      FIG. 17  shows an embodiment of the invention in which the first and second elements apparatus rotate along the long axis of the engine, thereby to reduce the aerodynamic consequences of a fixed first element configuration, to reduce asymmetric engine wear, and to more efficiently deflect debris and/or birds. In the figure, the base of the deflector apparatus  1702  is contiguous with engine  1700 , but is able to rotate about the long axis of the engine. 
         [0115]    Embodiments of the inventions hereinabove are possible in which: 
         [0000]    1) There is more than one distal cable running around the circumference of the device, to impart additional stability;
 
2) There are two or more cables running in parallel through the transverse/ non-distal second elements (one cable illustrated hereinabove);
 
3) The cable is replaced or supplemented by one or more ribbon shaped elements;
 
4) There are two tandem deflector apparatuses, each of which has the appearance of all of the protection elements shown in  FIG. 11A  (or  11 B,  1 A,  1 B,  8 A or  8 B). In a preferred embodiment of the invention, the first elements of the first apparatus are placed so that debris which passes through the outer apparatus is geometrically unlikely to pass through the second apparatus. The longitudinal first elements of the outer apparatus may have a different angular location than those of the inner apparatus, and/or the transverse elements of the outer apparatus may be situated in a more (or less) distal location than those of the inner apparatus. The outer apparatus may rotate (a) at a different speed than the inner one; and/or (b) in a different direction than the inner one;
 
5) The arrangement of first elements functions to (a) deflect airborne debris, and/or (b) break up airborne degree into smaller pieces.
 
6) Embodiments of the invention with other first element retraction and extension mechanism are possible.
 
7) Embodiments of the invention with other stabilizing mechanisms for the distal end of the first elements are possible.
 
8) Embodiments of the invention with a device, such as a device for passing electric current through the deflector elements, for maintaining the temperature of the elements above freezing, thereby to prevent formation of ice on the deflector.
 
         [0116]    There has thus been shown and described novel apparatus and methodology for controlling an implantable medical device which fulfills all the objects and advantages sought therefor. Many changes, modifications, variations and other uses and applications of the subject invention will, however, become apparent to those skilled in the art after considering this specification and the accompanying drawings which disclose the preferred embodiments thereof. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention, which is to be limited only by the claims which follow.