Patent Publication Number: US-2018050791-A1

Title: Aircraft landing gear and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit under 35 U.S.C. 371 based on co-pending International Application No. PCT/CA 2015/000147 filed Mar. 10, 2015, and published as WO 2016/141447, the specification and drawings thereof being incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to the field of amphibious aircraft and to landing gear for aircraft. 
     BACKGROUND 
     Amphibious aircraft are designed to land either on water or on land. Amphibious aircraft may typically be of two types, namely those with a pair of pontoons; and true flying boats with a water-tight hull. For fixed-wing aircraft, whether using skis or a hull, there will be a forward, or leading, direction, and a rearward or trailing direction. 
     In either instance it is possible to land, or to attempt to land, a fixed wing amphibious aircraft with the landing gear in an inappropriate configuration. That is, it is possible to make a landing on terrain with the wheeled landing gear retracted; and it is possible to make a landing on water with the wheeled landing gear extended. One cause of accidents in amphibious aircraft is landing in water with the wheels down. A water landing with wheeled gear extended may be catastrophic: as the gear descends into the water, it may tend to function as an oar or paddle that generates a substantial overturning moment on the aircraft, such as may tend to flip the aircraft over on its nose (if the gear plunges into the water symmetrically) or to spin and flip the aircraft, possibly in cartwheel fashion, if one wheel catches the water before the other. In either case the result may be very significant damage or personal injury, or both. 
     Alternatively, when the aircraft lands on terrain with the wheeled landing gear retracted, the effect may be that of a belly landing, with the possibility of doing significant damage to the aircraft hull (or pontoons). Damage may similarly occur if one or another wheel of the landing gear extends, while one or more other wheels remain retracted. As amphibious aircraft may, by their nature, fly to destinations that may have non-optimal field conditions, retrieving a damaged aircraft after an unintentional gear-up landing may itself become an undesired adventure. 
     SUMMARY OF THE INVENTION 
     In an aspect of the invention there is a fixed-gear amphibian aircraft. 
     In another aspect of the invention there is a fixed gear amphibian aircraft having a movably mounted water-riding hull portion. In a feature of that aspect, the hull portion is resiliently mounted. In a further feature of that aspect, the water-riding hull portion is mounted forwardly or, and as a shield for, a first wheel if the fixed gear. In another feature, the water-riding hull portion is mounted to move when the fixed gear deflects under load. 
     In another aspect of the invention there is an amphibian aircraft having at least a first fixed landing gear. 
     feature, the aircraft has a fixed nose gear. In another feature, the aircraft has tricycle landing gear. In another feature, all of the landing gear is, or are, fixed landing gear. In another feature, the landing gear includes at least one resiliently mounted landing gear. In another feature, the aircraft has at least a first water riding member mounted to extend forwardly of the first fixed landing gear. In still another feature, the first water-riding member is movably mounted. In yet another feature, the first water-riding member is mounted to deflect when the first fixed landing gear deflects. 
     In another aspect of the invention, there is a landing gear for an amphibious aircraft. The landing gear includes a wheel for rolling contact with a landing surface, and a deflector. The deflector defines a water-riding hull extending predominantly forwardly of the wheel. The deflector has an accommodation in which the wheel is mounted. The wheel extends partially downwardly proud of the deflector. The wheel and the deflector are mounted to move together, with the wheel protruding partially downwardly proud of the deflector. The landing gear is a single position landing gear. 
     In a feature of that aspect of the invention, the wheel is resiliently mounted in a single position, and is resiliently movable in a range of motion in response to loading, the water-riding hull being correspondingly movable in co-operation with the wheel. In another feature, the range of motion has a first end of travel and a second end of travel. The first end of travel is a fully loaded position, and the second end of travel is an unloaded position. In another feature, immediately forward of the wheel the deflector has a centerline slope forwardly and upwardly of the wheel of less than 30 degrees from horizontal when the wheel is in the unloaded position. In still another feature, in the fully loaded position, immediately forward of the wheel the deflector has a centerline slope forwardly of the wheel that is tangent to horizontal. 
     In another feature, the deflector forms one leg of a four-bar linkage, and the wheel is carried in a seat defining at least one other leg of that four-bar linkage. In still another feature the wheel has a foremost exposed portion and at the foremost exposed portion of the wheel a tangent to the wheel, when seen in side view has an angle of less than 45 degrees of arc from horizontal. In yet another feature the deflector has an opening formed therein, and the wheel protrudes through the opening. In another feature, the opening has a first edge portion running along a first sidewall of the wheel, and an opposed second edge portion running along a second sidewall of the wheel. In still another feature, the deflector has a first side portion, a second side portion, and a keel portion therebetween, the wheel being mounted between the first side portion and the second side portion. In another feature, the deflector extends at least three wheel diameters forward of the wheel. In yet another feature, immediately forward of the wheel the deflector has a centerline slope forwardly and upwardly of the wheel of less than 20 degrees from horizontal. In still another feature, the deflector has a sacrificial spine. In a further feature, the sacrificial spine is exposed and foremost, whereby in a gear-up landing the sacrificial spine is closer to the ground than any other non-wheel structure. 
     In another aspect of the invention, there is an amphibious aircraft having a wheeled landing gear for landing on a landing field. The wheeled landing gear is a fixed gear having a range of motion between an unloaded position and a fully loaded position. The landing gear is mounted within, and extends partially downwardly proud of, a movable landing gear housing, or housings, that define water-engaging surfaces forwardly and laterally of the landing gear and, when the landing gear moves within the range of motion, the landing gear housings and the landing gear move together, with the landing gear extending partially downwardly proud thereof. 
     In a feature of that aspect, the landing gear is a tricycle landing gear. In another feature, one of the landing gear wheels is a steerable nose gear. In a further feature, as installed on the amphibious aircraft the landing gear housing defines one bar of a four bar linkage. In another feature, the shell has a keel extending along the leading portion thereof. In another feature, the keel is a sacrificial wear member. In a further additional feature, the landing gear housing, or shell, has an external surface defining an external surface of the amphibious aircraft during both flight and water borne operation. In still another feature, the shell has at least one hydrofoil member mounted thereto. 
     It may be understood that the various aspects and features may be mixed and matched as may be appropriate. It may also be understood that the foregoing is not intended to be an exhaustive listing of aspects and features of the invention. These and other aspects and features of the invention may be understood with reference to the description which follows, and with the aid of the illustrations of a number of examples. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The description is accompanied by a set of illustrative Figures in which: 
         FIG. 1  is an isometric, general arrangement view of a portion of an amphibious aircraft shown in intermittent dashed line, with landing gear nose wheel and main gear housing assemblies shown in dashed lines, and landing gear transmission assembly members shown in solid lines for the purpose of establishing the general spatial arrangement of the various components of the aircraft; 
         FIG. 2 a    shows a side, or elevation, view of the amphibious aircraft portion of  FIG. 1 , with wheeled landing gear in the up or retracted position or condition; 
         FIG. 2 b    shows a side, or elevation, view of the amphibious aircraft portion of  FIG. 1 , with wheeled landing gear in the down or extended position or condition; 
         FIG. 3 a    is an isometric, general arrangement view of an enlarged detail of a steerable nose gear of the aircraft of  FIG. 1 ; 
         FIG. 3 b    is a side, or elevation, view of the steerable nose gear of  FIG. 3 a    in the retracted position; 
         FIG. 4 a    is an isometric, general arrangement view of an enlarged detail of the left main gear of the aircraft of  FIG. 1 ; 
         FIG. 4 b    is a side, or elevation, view of the left main gear of  FIG. 4 a    in the retracted position; 
         FIG. 5 a    shows an isometric, view of a main landing gear housing assembly of the aircraft of  FIG. 1  in a retracted position or condition seen from inboard, rearward and below; 
         FIG. 5 b    an isometric view of the landing gear housing assembly of  FIG. 5 a    from outboard, rearward and below; 
         FIG. 5 c    shows a trailing end view of the landing gear housing assembly of  FIG. 5 a    looking forward; 
         FIG. 5 d    is an outboard side view of the landing gear housing assembly of  FIG. 5   a;    
         FIG. 5 e    is an outboard side view of the landing gear housing assembly of  FIG. 5   a;    
         FIG. 6 a    shows an isometric, view of a main landing gear housing assembly of the aircraft of  FIG. 1  in an extended position or condition seen from inboard, rearward and below; 
         FIG. 6 b    an isometric view of the landing gear housing assembly of  FIG. 6 a    from outboard, rearward and below; 
         FIG. 6 c    shows a trailing end view of the landing gear housing assembly of  FIG. 6 a    looking forward; 
         FIG. 6 d    is an outboard side view of the landing gear housing assembly of  FIG. 6   a;    
         FIG. 6 e    is an outboard side view of the landing gear housing assembly of  FIG. 6   a;    
         FIG. 7 a    shows a perspective view of a steerable nose wheel landing gear housing assembly of the aircraft of  FIG. 1  in a retracted position as seen from one side, in front, and below; 
         FIG. 7 b    is a side view of the steerable nose wheel landing gear housing of  FIG. 7   a;    
         FIG. 7 c    is a front view of the nose wheel landing gear housing of  FIG. 7   a;    
         FIG. 8 a    shows a perspective view of a steerable nose wheel landing gear housing assembly of the aircraft of  FIG. 1  in a retracted position as seen from one side, in front, and below; 
         FIG. 8 b    is a side view of the steerable nose wheel landing gear housing of  FIG. 8   a;    
         FIG. 8 c    is a front view of the nose wheel landing gear housing of  FIG. 8   a;    
         FIG. 9 a    shows a simplified side view of the main landing gear of  FIG. 5 a    in the retracted position; and 
         FIG. 9 b    shows the main landing gear of  FIG. 6 a    in the extended position. 
         FIG. 10 a    shows an alternate embodiment to that of the aircraft of  FIG. 1 , with landing gear in an uncompressed position or condition; 
         FIG. 10 b    shows the aircraft of  FIG. 10 a    with landing gear in a compressed or deflected position or condition; 
         FIG. 11 a    is a side view of the aircraft of  FIG. 10 a   ; and 
         FIG. 11 b    is a side view of the aircraft of  FIG. 10   b;    
     
    
    
     DETAILED DESCRIPTION 
     The description that follows, and the embodiments described therein, are provided by way of illustration of an example, or examples, of particular embodiments of the principles, aspects or features of the invention. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the invention. In the description, like parts are marked throughout the specification and the drawings with the same respective reference numerals. The drawings may be taken as being to scale unless noted otherwise. 
     The terminology used in this specification is thought to be consistent with the customary and ordinary meanings of those terms as they would be understood by a person of ordinary skill in the aircraft industry in North America. The Applicant expressly excludes all interpretations that are inconsistent with this specification, and, in particular, expressly excludes any interpretation of the claims or the language used in this specification such as may be made in the USPTO, or in any other Patent Office, other than those interpretations for which express support can be demonstrated in this specification or in objective evidence of record, (for example, earlier publications by persons not employed by the USPTO or any other Patent Office), demonstrating how the terms are used and understood by persons of ordinary skill in the art, or by way of expert evidence of a person or persons of at least 10 years&#39; experience in the aircraft industry in North America or equivalent. 
     In terms of general orientation and directional nomenclature, for aircraft described herein the longitudinal or lengthwise direction is defined as being coincident with the fore-and-aft direction of flight of the aircraft in straight and level flight. In the case of a fixed wing aircraft, the longitudinal direction is parallel to the rolling direction of the wheeled landing gear and to the keel direction of the hull or pontoons, as may be. The leading direction, or leading edge lies toward the forward direction of travel; the rearward or trailing direction or trailing edge is oriented away from (i.e., backwards relative to) the normal direction of advance of the aircraft. Unless otherwise noted, vertical, or upward and downward, are terms that use the landing terrain (or, alternatively, undisturbed water level), as a datum. In the context of the aircraft as a whole, the terms cross-wise, lateral, spanwise, or laterally outboard, or transverse, or transversely outboard refer to a distance or orientation relative to the longitudinal centerline of the fuselage, or of the landing gear nacelles or sponsons or pontoons, as may be. The commonly used engineering terms “proud”, “flush” and “shy” may be used herein to denote items that, respectively, protrude beyond an adjacent element, are level with an adjacent element, or do not extend as far as an adjacent element, the terms corresponding conceptually to the conditions of “greater than”, “equal to” and “less than”. 
     The directions correspond generally to a Cartesian frame of reference in which the x-direction is longitudinal, the y-direction is lateral, and the z-direction is vertical. Pitching motion is angular motion of the aircraft about a horizontal axis perpendicular to the longitudinal direction. Yawing is angular motion about a vertical axis. Roll is angular motion about the longitudinal axis. Given that the aircraft described herein may tend to have a longitudinal axis of symmetry, a description of one half of the aircraft may generally also be intended to describe the other half as well, allowing for differences between right hand and left hand parts. Also, it may be taken as a default that the structure of the aircraft is of aluminum fabrication except as otherwise shown in the illustrations or indicated in the text, although reinforced composite structure may also be employed. Other materials, such as stainless steel, or wood, might be also be used for some components. 
     In this discussion it may by understood that persons of ordinary skill are familiar with the aircraft construction and maintenance in North America, and may include aircraft maintenance engineers having knowledge of US Department of Transportation, Federal Aviation Administration publication EA-AC 43.13—1A &amp; 2A “Acceptable Methods, Techniques and Practices, Aircraft Inspection and Repair”, or any successor publication thereof, as updated at the date of priority filing of this specification. This specification is to be interpreted in a manner consistent with that publication. 
     The discussion herein pertains to amphibious aircraft. The terminology “amphibious aircraft” is understood to be, and is intended to be understood as being, interchangeable with the terms “amphibian aircraft” or simply “amphibian”. An amphibious aircraft, or amphibian, by definition is an aircraft that is capable of landing on terrain in one mode, and also capable of landing on water in another mode. 
     There is also discussion herein, and distinction between “fixed gear” and retractable landing gear. For the purposes of this discussion, retractable landing gear is landing gear whose position is selectable between an extended or deployed, or “down” position, and a raised or retracted, or “up” position. In many aircraft, when the landing gear are “up” or retracted, the wheels of the lading gear are concealed within a faired housing or cowling, such as a nacelle or a hull blister. However, it is not necessary that the wheels be fully hidden. It is possible to have a retracted position in which the wheels are only partially concealed, or partially faired. In either case, the aircraft has a drive, or drive train or transmission system, or linkage or assembly that the pilot operates to select between a first position (e.g., the raised or “up” position) and a second position (e.g., the lowered, extended, or “down” position). The transmission may be a mechanical system of linkages, or an electrical system, or an hydraulic or pneumatic system, or a mixture or combination of electrical, mechanical or hydraulic elements. 
     In a “fixed” landing gear aircraft, there may tend not to be a landing gear drive or transmission, and the pilot is not able to select as between positions. The gear has a single mounting condition or position. While the term “fixed” may be used in the sense of a permanent mounting and lack of choice on the part of the pilot, the gear itself may nonetheless retain a degree of movement in respect of one or more degrees of freedom in the sense of tolerating deflection, as, for example, during landing on terrain. Most typically the deflection is a resilient deflection since the landing gear is sprung. The resilience may arise from the structure of the landing gear legs or struts, or from spring or spring-damper systems with which the landing gear is provided. 
       FIG. 1  shows a portion of an aircraft,  20 . Aircraft  20  is an amphibious aircraft. Although principles, aspects, and features of the invention herein may be applied to rotary wing aircraft as may be appropriate in respect of landing gear apparatus for use in landings with non-trivial forward approach velocity, it may be taken that in the embodiment of  FIG. 1  aircraft  20  is a fixed-wing aircraft. Aircraft  20  may be a high-wing monoplane, with a fuselage indicated as  22  and the wing structure indicated as  24 , the join of wing structure  24  being at the top of fuselage  22 . Wing  24  extends laterally outboard to port and starboard of fuselage  22 . 
     Fuselage  22  of aircraft  20  may further include a lower portion  26  which may have formed on the underside thereof a hull  28  for use in water, hull  28  having a leading portion such as may be termed a bow, and a trailing portion, such as may be termed a stern, or step  30 . Hull  28  may be curved and, in the main portion thereof, may have a profile centrally downwardly and rearwardly curved to a central, longitudinally extending keel  32 . The tail  34  of aircraft  20  may extend rearwardly and generally upwardly of hull  28 . 
     Hull  28  may include lateral bulges  36  such as may tend to extend laterally outboard of the lower portions of fuselage  22 . Bulges  36  may also extend somewhat downwardly and may each define a sponson  38 . Sponson  38  may include, or may have mounted thereto, a main landing gear housing, or cowling, or apparatus, such as may be designated as main gear housing assembly  40 , which, may be either left hand or right hand. Although asymmetric aircraft are known, aircraft  20  may be generally symmetrical about its longitudinal centerline, such that the right hand main gear housing assembly is the mirror image of the left hand one, and the description of one is the same as the other but for their handedness. Hull  28  may also include a nose landing gear housing, or cowling, or apparatus such as may be designated as nose gear housing assembly  42 . The nose gear mounted within nose gear assembly  42  may be a steerable nose gear. The left and right hand main gear and the steerable nose gear may define a tricycle undercarriage, and, to the extent that they include respective main wheels  44  and nose wheel  46 , provide a tricycle landing gear for use on terrain, be it tarmac, hardpack, a prepared landing field, a beach, or other surface suited to wheeled motion. The landing gear may be extended, such as for a wheeled landing; or may be retracted, such as for a water-borne landing. 
     Referring to  FIG. 3 a   , nose wheel  46  of assembly  42  is mounted in a clevis or yoke  52  having a central, vertically oriented pivot shaft that is pivotably mounted in a mating steering mount assembly  54 . Steering mount assembly  54  includes a pair of laterally spaced apart left and right side frames  56 , each of which may be substantially planar, the two being mutually parallel. When viewed in profile, side frames  56  have a generally four-sided shape, interrupted by a rearwardly extending arm  58 . Side frames  56  are held in spaced relationship the rearwardly mounted box-structure of the steering head shaft mount  60 , and by a forward lateral shear web  60  mounted on, or across, the downwardly and rearwardly angled lower edge of side frames  56 . 
     Upper and lower linkages  62  and  64  are pivotally mounted at the upper and lower forward corners of sideframes  56 . Linkages  62  and  64  are of the same length. Each has a first end mounted to the aircraft structure, such as in the nose of the fuselage as at  66  and  68  respectively, that first mounting being a pivotal mounting having a single degree of freedom, namely pivotal motion about the y-axis. The second end also has pivotal mountings having axes of rotation in the y-direction. Since the respective first ends and second ends are spaced the same distance apart, the quadrilateral of the four bar linkage so formed (i.e., two linkages, the main aircraft fuselage structure, and sideframes  56 ) defines a parallelogram such that while sideframes  56  follow the arc of the second ends (i.e., the ends distant from fixed structure) of linkages  62  and  64 , the angular orientation of sideframes  56  about the y-axis is constant. Thus the orientation of the z-axis of the steering stub shaft may tend to remain vertical. Steering yoke  52  has a laterally extending tiller or arm  70  and steering linkage  72  by which nose wheel  46  may be turned left and right, as appropriate. 
     The nose gear assembly, and therefore nose gear housing assembly  42  which moves with the nose gear, is driven up and down by a nose gear actuator assembly, indicated generally as  74 . Actuator assembly  74  includes a main shaft, or torque tube  76  that extends laterally across the fuselage (i.e., in the y-direction) between pivotal mountings mounted to the fuselage structure, such as bushings. Torque tube  76  is able to pivot in a single degree of freedom, namely angular rotation about the y-axis. An input arm  78  is mounted generally centrally to toque tube  76 , and may be pushed or pulled to create a moment couple driving torque tube  76  clockwise or counter-clockwise. Left and right hand output arms  80  extend forwardly and downwardly of torque tube  76  to straddle nosewheel  46 . A lateral cross-member  82  is rigidly mounted to, and across, sideframes  56 , and extends laterally from either side of the lower aft-ward corner thereof. Lateral cross-member  82  may be a shaft that is free to rotate about the y-axis. Drag links  84  extend between the respective ends of lateral cross-member  82  and the distal ends of output arms  80 , such that when torque tube  76  turns, the ends of arms  80  move clockwise or counter-clockwise, drawing (or pushing) on drag links  84 , thereby forcing shaft  86 , (and hence sideframes  56  and nose wheel  46 ), to follow the arc of motion of links  62 ,  64 . Assembly  42  may also include a return spring, or counter-weight spring,  88 , such as may tend to bias nose gear housing assembly  42  to the retracted position. When not being moved, the nose gear assembly, or actuator assembly  76 , as may be, has locks that retain the nose gear in either the up position or the down position, with associated up-lock and down-lock indicators. 
     Nose gear housing assembly  42  is, not surprisingly, mounted at or near the nose of the aircraft. Nose gear housing assembly  42  may also have, or be, a nose gear shield, or deflector assembly, or shoe, which may be identified generally as nose gear deflector  90 . Deflector  90  is pivotally mounted to fuselage  22  at a pivot fitting location well forwardly of nose wheel  46 , as indicated at location  92 , and may be co-axially mounted with either first end  66  or first end  68  of linkages  62  or  64 , such that deflector  90  may follow the same arc. The axis (or respective axes) of rotation of the pivot fitting connection at location  92  (be it at  62  or  64 ) runs horizontally cross-wise to the aircraft longitudinal centerline. Thus any point of nose wheel landing gear housing assembly  42  moves in an arc in a vertical plane parallel to the longitudinal centerline (and the presumed direction of forward motion) of aircraft  20  more generally. Deflector  90  may have the form of a hull or prow, or stem, or planing surface with a central ridge or stem, such as may tend to displace or ride over, water in the manner of a ski or planing hull. Although deflector  90  may have an aerodynamic or hydrodynamic form, deflector  90  is not a cosmetic cowling. It has the structural strength to support the aircraft when landing on water; it is also intended to have structural strength to support the aircraft in an unintentional gear-up landing on terrain, should the range of deflection on impact exceed the limits of deflection of nose wheel  46  alone while nose wheel  46  is in the retracted position. To that end, the longitudinal centerline of deflector  90  may have a central spine, or rib, or keel, or protector, or wear member, wear strip, such as may be in the nature of a sacrificial member or sacrificial keel  94  extending along the most exposed centerline portion thereof. In the event of a hard landing, or in the event of striking a floating object, sacrificial keel  94  may tend to contact the terrain or floating object first, and skid along or over it. To either side of sacrificial keel  94  extending obliquely rearwardly, upwardly and laterally inboard or outboard as the case may be, are first and second side portions identified as  93 . Which terminate rearwardly in substantially vertical sidewalls  95  that seat within the side edges of the well in fuselage  22  that accommodates nose wheel housing assembly  42  more generally. To the extent that sacrificial keel  94  is thereby damaged, it is intended that it may be replaced as necessary or suitable. Deflector  90  may be attached to, or suspended from, spring  88 . 
     As can be seen, deflector  90  extends forwardly of wheel  46  on a gentle curve that is more forwardly than upwardly, and that, at the point of intersection of the projected curve of the hull and the tangent of the profile of the tire is an oblique angle of perhaps something greater than 120 degrees. As can be seen, nose wheel  46  is mounted within nose gear housing assembly  42 , such that the bulk of wheel  46  is between the inboard and outboard sides of the housing, and the lowermost cusp or portion of wheel  46  extending through the accommodation, namely aperture  48 , downwardly proud of the deflector centerline. In the case of a steerable nose-wheel, aperture  48  is of a shape (such as circular in plan view) to permit wheel  46  to turn. Nose gear housing assembly  42  has a main portion that extends forwardly of wheel  46 , but also side portions that extends alongside, and outwardly and upwardly, of the axle, and most of the sidewall of the body of wheel  46 . Thus wheel  46  is mounted within nose gear housing assembly  42 , generally toward the rearward or trailing end thereof distant from the pivot mounting at the forward or leading end of housing  42 . 
     In the example, the extent to which wheel  46  extends downwardly proud may by 4-6 inches. Expressed differently, the point of intersection of the curves may be somewhere between the 7 o&#39;clock and 8 o&#39;clock positions. Expressed differently again, the wheel may protrude proud of the surface a distance S, where S=D(1−Cos(Theta)), D being the outside diameter of wheel  46  and theta being the angle (measured from the six o&#39;clock position of wheel  46 ) at which the wheel profile intersects the deflector profile on the centerline. Theta may be in the range of perhaps 15 to 65 degrees, and, in one embodiment, may be in the range of 30-50 degrees. The general tangent slope at mid arc of deflector  90 , indicated as alpha, may be of the order of 15-40 degrees from the horizontal. In the embodiment shown, it may be 20-35 degrees, with the local tangent angle being closer to 15 or 20 degrees immediately forwardly of nose wheel  46 , and closer to 35 or 40 degrees in the neighbourhood of forward pivot point  68 . Expressed differently yet again, deflector  90  has a length L 90  forwardly of the axle of nose gear wheel  46  that may be in the range of about 3-8 times the diameter of nose gear wheel  46 . 
     In general, deflector  90  provides a smooth lead-in-surface extending forwardly of wheel  46  for engaging, and riding upon, water—like a ski, or hull or slipper or shoe. In some embodiments, the surface of deflector  90  may also extend aftward of wheel  46  in a trailing edge tail. Wheel  46  extends partially downwardly proud of the profile of deflector  90 . The extent to which it stands downwardly proud may correspond to the expected deflection of the tire of wheel  46  during a normal landing, plus an allowance of extra travel, perhaps 50% of nominal normal landing load travel. In the event that aircraft  20  should land on water with the nose gear extended, nose wheel  46  can only partially immerse itself before the aftmost portion of deflector  90  also engages the water. At speeds of interest, the clock-wise counter-acting lift arising from deflector  90  planing on the water may tend to counter-act the counter-clockwise pitching moment generated by hydrodynamic drag on the exposed protruding portion of wheel  46 . 
     As illustrated in  FIGS. 7 a  and 8 a   , the forward facing surface deflector  90  of housing assembly  42  defines a portion of the aerodynamic form, or fairing, of the nose of the aircraft in both the retracted and the extended conditions. As seen in  FIG. 7 b   , in the retracted position deflector  90  seats flush with the aftwardly extending keel of fuselage  22 . 
     In some embodiments, aircraft  20  may have hydrofoil members  96  such as may be mounted to the upstanding laterally spaced apart sidewalls  95  of housing assembly  42 . In the retracted position, hydrofoils  96  seat in accommodations  97  defined in fuselage  22 , such that hydrofoils  96  are substantially flush with the adjacent structure and form a relatively smooth, continuous streamline or continuous fairing surface as shown in  FIGS. 7 a , 7 b  and 7 c   . In the extended position of the nose gear as shown in corresponding  FIGS. 8 a , 8 b  and 8 c   , hydrofoil members  96  are exposed to passing water flow, and, upon contact with the water, may tend to exert a lifting force that is transmitted back through the structure to lift the nose of aircraft  20  (i.e., to give aircraft  20  a clockwise turning moment in the side view of  FIG. 7 b    to counter-act the counter-clockwise over-turning moment such as may be generated by wheel  46  (or wheels  44  further aft, as may be). In the embodiment shown, hydrofoil members  96  are mounted abreast of wheel  46 , at a level comparable to, and in some embodiments slightly above, the axle centerline of wheel  46 . 
       FIG. 4 a    shows the landing gear transmission, identified generally as  100 . Many structural features have been omitted from this illustration for the purpose of making the landing gear components more easily visible. As with nose gear housing assembly  42 , main gear housing assembly  40  (be it port or starboard) has main gear wheel  44  installed in a landing gear housing generally indicated as  102 . Housing  102  has a stationary upper, or main, portion  104 , which is rigidly mounted to sponson  38 ; and a co-operating, movable, or lower portion  106 , which may include a pivotally mounted main gear vane, or protector, deflector, or deflector assembly  110 . The pivot mounting may be at the first, or leading, end of housing  102 . Inasmuch as housing  102  may ultimately transmit the reactive force from the main gear to carry the aircraft structural load, housing  102  is structurally connected to a laterally extending spar or beam structure, indicated as  108 . Structure  108  may include an I-beam and a deep central frame assembly  98  as shown in  FIG. 4 a   . The ends of beam-and-frame structure  98  are cantilevers, which have a measure of vertical flex, and the main gear loads are carried at the ends of the cantilevers. Main portion  104  may have an inboard wall  112 , an outboard wall  114 , and an upper wall or covering or cowling  116  all of which may be rigidly interconnected, and which may have a faired aerodynamic shape. Housing  102  is mounted to the outboard margin of sponson  38 , be it port or starboard. Sponson  38  is water tight, and the bottom wall of sponson  38  forms a portion of hull  28 . Housing  102  has a downwardly opening accommodation  118 . Accommodation  118  is generally rectangular, being much longer in the x-direction than wide in the transverse y-direction, such as may be co-operatively shaped matingly to work with the generally box-shaped main gear slipper, or shoe,  120  of lower portion  106 . 
     As seen in  FIGS. 5 a  to 5 e   , and in  FIGS. 6 a  to 6 e   , shoe  120  may have an inboard longitudinal wall  122 , an outboard longitudinal wall  124 , a bottom deflector plate  126 , joined together to form a generally U-shaped structure, with side walls  124 ,  126  being generally vertical, parallel and spaced apart. Main gear wheel  44  is mounted between the inboard and outboard portions or walls of deflector shoe  120 . There may be lateral shear webs or shear frame braces  123  extending laterally therebetween forward of main gear wheel  44  to maintain walls  122  and  124  in spaced parallel relationship from each other. The forward end of shoe  120  is enclosed, as where bottom deflector plate  126  is curved forwardly and upwardly to define the forward tip of the ski or slipper, or vane, however it may be called. A pivot mount is located at the foremost tip of shoe  120 , being indicated as  128 , and is mounted in structural load spreading bushing assemblies in main portion  104 . The axis of rotation of the pivot mounting may be horizontal and cross-wise to the vertical plane of symmetry of the aircraft centerline. Bottom deflector plate  106  may be backed by reinforcements in the nature of longitudinal stringers and transverse frames suitable for maintaining its structural integrity in expected operation. 
     Bottom deflector plate  106  has a rearwardly located relief  107  near its trailing end to accommodate protrusion of main gear wheel  44 . As shown in  FIGS. 5 a  and 5 b , 6 a  and 6 b   , relief  107  may have the form of an accommodation  130  which may be a rectangular opening, or it may be a generally oval or rounded elongate opening corresponding to the shape of the tire of wheel  44 . The opening is such as to have a first edge portion forwardly of wheel  44 , and side portions running along the sidewalls of wheel  44 . Main gear wheel  44  seats, or is mounted within assembly  40  between the sidewalls thereof, with a portion, or cusp of wheel  44  protruding through relief  107 . Since wheel  44  moves and housing assembly  40  move together, wheel  44  protrudes from plate  106  in both the extended and retracted positions of the landing gear. Bottom deflector plate  106  may also have, or be formed to have, a lengthwise extending keel,  132 , which may have a replaceable sacrificial wear member or skid  134 . Skid  134  may be made of a consumable material such as stainless steel. As seen in  FIGS. 5 d  and 5 e    keel  132  is gently upwardly angled, being nearly horizontal at the point at which the foremost portion of wheel  44  crosses the profile of keel  132 , and is formed forwardly curvedly with an increasing angle of slope toward the nose. As may be understood, in a normal landing, shoe  120  may tend to plane along the water. In an inadvertent gear-up landing on terrain, wheel  44  may contact the terrain first, and only to the extent that the landing is heavy will shoe  120 , and, in particular skid  134 , ride along the terrain. In an inadvertent gear-down landing on water, even as fully deployed in  FIG. 5 e   , the clockwise overturning moment due to drag on the exposed portion of wheel  44  may tend to be counteracted by the lift generated in planing as soon as leading portion  136  of shoe  120  immediately forward of wheel  44  begins to bear on the water surface. The protective presence of the slipper or shoe  120  forward of wheel  44  may tend to limit or counteract the overturning drag that can be developed by water drag on wheel  44 . Further, considering  FIG. 3 a   , to the extent the nose gear deflector  90  may also engage the water, the counter-acting lifting force of deflector  90  planing on the water has a very long moment arm relative to wheel  44 . 
     The primary element of transmission  100  of  FIG. 4 a    is a laterally extending shaft  140  that extends outboard to both port and starboard. At its most outboard extremity shaft  140  is connected to a co-axial outer tube  142 , which may be termed a torque tube. At its most inboard end, torque tube  142  terminates at a lever arm  144  that has a hollow center to permit the passage of shaft  140 . Arm  144  extends to the top end of a damper or spring-damper combination, identified as shock absorber  146 . The other end of shock absorber  146  is mounted to a bushing, which is itself mounted to a load spreading bracket (not illustrated) within the frame of the fuselage or sponson. An input arm  150  is mounted to a sleeve  152  on shaft  140 . As may be understood, moving input arm  150  clockwise and holding arm  144  stationary will cause shafts  140  and  142  to wind up as two torque springs in series. 
     As shown in  FIG. 4 a   , the outboard end of torque tube  142  is carried in a bearing mounted to upper portion  104  of housing  102 . There may also be a central bearing at sleeve  152 , and another bearing mounted about torque tube  142  immediately outboard of arm  144 . At the outboard end of torque tube  142  is a first pair of matched rearwardly extending arms defining a first wishbone  154 . At the tips of the legs of first wishbone  154  is a cross-shaft  156  that ties the two tips together. A second wishbone  158  with hollow shaft mounted co-axially with cross-shaft  156 , and two extending legs (i.e., a fork or clevis, or wishbone) reach from shaft  156  to axle  160  of wheel  44 . The ends of axle  160  are mounted in seats or bushings that are themselves mounted to inboard wall  122  and outboard wall  124  respectively. The assembly so described defines a four bar linkage. That is, the first bar of the linkage is the fixed structure of the aircraft. The second bar of the linkage, effectively pivotally mounted to the fixed structure, is the first wishbone,  154 . The third bar of the linkage is the second wishbone  158 , and the fourth bar of the linkage is the deflector or slipper, or shoe,  120  which is pivotally mounted to the fixed structure of the first bar at pivot  128 . That is, relative to the fixed structure of the aircraft, shoe  120  defines the fixed radius arm constraining the arc of motion of wheel  46  and main gear bottom deflector plate  126 . Input to shaft  140  uniquely determines the position of first wishbone  154 , and therefore also the position of second wishbone  158  which functions as a drag link or slave link in this mechanism. Thus wheel  44  is limited to translation in a single degree of freedom along the circumferential arc described by the axle bushings mounted to deflector  120 . Given the relative length of the arm defined by deflector  120 , and given the close to horizontal orientation of the arm, that motion is substantially, predominantly, upward-and-downward. Wheel  44  is movable between retracted and extended positions, as shown. There is an up-lock, and there is a down-lock, not shown. On landing, shaft  140  and torque tube  142  provide a somewhat resilient response, that response being damped by shock absorber  146 . 
     Transmission  100  is driven between retracted and extended positions by actuator assembly  170  mounted within hull  28 . Actuator assembly  170  includes a motor (and motor control)  172 , a gear reducer  174  driven by motor  172 ; a worm drive  176  connected to the output of gear reducer  174 ; and a reciprocally movable actuator  178  driven by worm drive  176 . As will be understood, driving motor  172  in a first direction will cause the jack of actuator  178  to extend, driving arm  144  clockwise with the effect of extending the main gear; driving motor  172  in the opposite direction will cause the jack of actuator  178  to retract, driving arm  44  counter-clockwise, with the effect of retracting the main gear. Other arrangements of drives could be used. In each case, deflector  120  moves with the main gear, or, expressed differently, the deflector and the wheeled landing gear move together. 
     Sleeve  152  also carries an output interface, or output arm  180 , which is connected to a drag link  182 , which drives a bell-crank  184 . The output of bell crank  184  is connected to a shock absorber  186 , which in turn carries the aftmost end of a connecting rod  188 . Connecting rod  188  has a foremost end mounted to input arm  78  which drives torque tube  76  of nose gear assembly  42 . Shock absorber  186  may tend to provide a measure of damping decoupling of the nose gear from the main gear. Thus motion of actuator  178  drives all three wheels of the tricycle assembly in a co-ordinated manner up and down. In each case, the action of the respective wheel carries the associated deflector up and down as well. 
     Referring again to the main gear, deflector  120  protects the forward side of main wheel  44 . As noted, deflector  120  has a long and thin shape, deployed leading main wheel  44 . The moving protective deflector, or vane, or shoe, may extend 2-8 wheel diameters forward of the main gear axle centerline, and, as above, it may be positioned and angled to leave exposed only a portion of main wheel  44 , as seen from looking aft along the wheel centerline. 
     Expressed differently, the point of intersection of the curves of the profile of deflector plate  126  and wheel  44  may be somewhere between the 7 o&#39;clock and 8 o&#39;clock positions. Expressed differently again, the wheel may protrude proud of the surface a distance S, where S=D(1−Cos(Theta)), D being the outside diameter of wheel  44  and theta being the angle (measured from the six o&#39;clock position of wheel  44 ) at which the wheel profile intersects the deflector profile on the centerline. Theta may be in the range of perhaps 15 to 65 degrees, and, in one embodiment, may be in the range of 30-50 degrees. The general tangent slope at mid arc of deflector plate  126  may be of the order of 15-40 degrees from the horizontal. In the embodiment shown, it may be 20-35 degrees, with the local tangent angle being closer to 15 or 20 degrees immediately forwardly of main gear wheel  44 , and closer to 35 or 40 degrees in the neighbourhood of forward pivot point  68 . Expressed differently yet again, deflector plate  126  has a length L 126  forwardly of the axle of main gear wheel  44  that may be in the range of 2-10 times the diameter of main gear wheel  42 . Deflector  126  may provide a smooth lead-in-surface extending forwardly of wheel  44  for engaging, and riding upon, water—like a ski, or hull or slipper or shoe. Wheel  44  extends partially downwardly proud of the profile of deflector plate. The extent to which it stands downwardly proud may correspond to the expected deflection of the tire of wheel  44  during a normal landing, plus an allowance of extra travel, perhaps 50% of nominal normal landing load travel. In the event that aircraft  20  should land on water with the main gear extended, wheel  44  can only partially immerse itself before the aftmost portion of deflector plate  126  also engages the water. At any significant speed, the clock-wise counter-acting lift arising from deflector plate  126  planing on the water may tend to counter-act the counter-clockwise pitching moment generated by hydrodynamic drag on the exposed protruding portion of wheel  44 . 
     In an alternate, or additional, embodiment, main gear housing assembly  40  may include hydrofoil members, such as a first or outboard hydrofoil member  190  and a second or inboard hydrofoil member  192 , and, should the deflectors not be considered sufficient, hydrofoils  190  and  192  may tend also to generate a clockwise lifting moment tending to counteract the overturning moment arising from hydrodynamic drag. Hydrofoils  190  and  192  may be relatively small, and may have the appearance of relatively short “fins” extending laterally of the sponson structures respectively. Aircraft  20  may have respective outboard and inboard reliefs or rebates, or seats or accommodations  191  and  193  corresponding to hydrofoils  190  and  192 , such that in the retracted position of the landing gear, hydrofoils  190  and  192  are at least partially (in the case of hydrofoil member  190 ) or fully (in the case of hydrofoil member  192 ) concealed or seated in a position that is flush with the adjacent faired structure, giving a relatively smooth streamlined form. As above, in the extended position of the landing gear hydrofoils  190  and  192  are fully exposed. Hydrofoils  190  and  192  may be located generally abreast of wheel  44  and set at a level near the level of the axle of wheel  44 , such that in the event that a gear-down landing is made on water, and hydrofoils  190  and  192  may engage the water and begin to provide a lifting force even while the depth of wheel  44  in the water is relatively shallow. 
     In the event of a flat tire, or in the event of a gear transmission failure in which not all of the gear move to the selected position (be it up or down), the presence of nose deflector  90  and main gear deflector plates  126  may be such as to tend to provide a back-up skid surface for landing on terrain. 
     Nose wheel  46  has two rotational degrees of freedom—namely rotation about its axle, and pivoting rotation about its predominantly vertical steering shaft. Motion of the nose gear between retracted and extended positions is restricted to a single degree of freedom along the constrained arc of the parallelogram in the x-z plane. Deflector  90  has a single degree of freedom of motion—namely translation in the arc in the x-z plane associated with motion of the nose gear assembly generally. The up-and-down orientation of the nose gear steering shaft remains constant in the x-z plane. 
     Similarly, the main gear four bar linkage is constrained to motion in an x-z plane, and the wheel itself, while rotatable in the normal manner about its own axis of rotation to permit wheeled operation, is restricted to the single degree of freedom of travel along the arc traced by the bushings of shoe  120  relative to pivot point  128 . 
     The wheeled landing gear deflectors or shoes or slippers or protectors, however termed, shown and described herein are not to be confused with landing gear “spats”. First, “spats” are aerodynamic fittings employed to reduce fixed landing gear drag that generally are not intended to, and typically do not, produce lift (aerodynamic or otherwise); the shoes described herein are hydrodynamic lift members. Second, true “spats” tend to be a feature of fixed landing gear rather than retractable landing gear. Third, “spats” are aerodynamic fairings of very light structure, as opposed to being structural members intended to take substantial dynamic loads such as landing loads. Fourth, spats tend to extend predominantly rearwardly of the axle of the wheel, with the form of a trailing edge of diminishing section to reduce rearward separation of airflow. The present hydro-dynamic deflectors or slippers or shoes extend predominantly forwardly of the gear, as opposed to aftward. 
     As described above, the anti-flip, or flip discouraging aspect is passive. That is, it does not rely on pilot intervention, or on electronic sensing or control systems to prevent landing in the wrong configuration. Of course, aircraft  20  may have such warning systems. However, even if they fail, the deflector may tend to work to protect against an overturning moment. 
     The deflector moves with the landing gear, and the forward facing surface of the deflector also defines a portion of the exterior fairing of the aircraft in its normal operation in flight. That is, the deflector is not concealed behind other structure, or inside a nacelle in the retracted position, but rather forms a surface of the normal exterior of the aircraft. In the retracted position that surface may be flush with adjacent external surfaces to form a relatively smooth, streamlined form. The deflector protects its respective wheel in both the retracted and the extended position. 
     Also, as described, the wheel protrudes from the deflector, or shoe, structure in both the extended and the retracted position. In both positions the wheel is in its rolling orientation, i.e., the axle is horizontal and perpendicular to the line of forward motion of the aircraft. In both positions the shoe or deflector protects, or encloses, more than half of the wheel, with the sides of the shoe or deflector extending from the downward portion thereof upwardly and rearwardly or the axle. That is, the wheel is covered on both front and sides. 
     In the embodiment of  FIGS. 10 a , 10 b , 11 a  and 11 b    there is an amphibious aircraft  220 , which, unless otherwise noted, may be taken as being the same, or substantially the same, as aircraft  20 , but that does not have a drive train, or actuator and mechanical transmission, for moving the landing gear from an extended (or “down”) position to a retracted (or “up”) position. That is, aircraft  220  is a fixed-gear amphibian, and, more particularly, a fixed gear flying-boat amphibian. It has a fixed, or single position, gear. The fixed gear is sprung, i.e., resiliently mounted, such that there is a range of motion of deflection of the wheels such as may be desired for lending on terrain, without a selection of positions. In respect of aircraft  220 , it may be taken that the views of  FIGS. 5 a  to 5 e  and 6 a  to 6 e , 7 a  to 7 c , 8 a  to 8 c , 9 a  and 9 b    apply to aircraft  220  as they do to aircraft  20 . However, rather than representing selected “up” and “down” positions, the two positions shown may be thought of as representing a range of travel from the passive, extended, or no-load position, to the passive, deflected position at full load during landing, e.g., landing on terrain. To see the differences between aircraft  220  and aircraft  20 ,  FIG. 10 a   , with the landing gear deflected upward as under load, and  FIG. 10 b    with the landing gear in an un-loaded condition may be compared with  FIGS. 1, 3   a  and  4   a . Similarly,  FIGS. 11 a  and 11 b   , the corresponding side views, may be compared with  FIGS. 2 a , 2 b , 3 a , 3 b    and  4   b.    
     The embodiment of aircraft  220  of  FIGS. 10 a , 10 b , 11 a  and 11 b    may be thought of as being equivalent to the embodiment of  FIG. 1  with the gear selected “down”, except that there is no selection. The gear has only a single “fixed” position. The fixed position nonetheless is the fixed position of a resilient suspension, the resilience of the suspension permitting deflection of the wheels. In this deflection, the leading cowlings, or protectors, or deflectors, or vanes, or shoes, however they may be termed, move with the wheels. The lead-in vane remains in the position to engage water at all positions of travel of the wheels within their resilient range of motion. Expressed differently, aircraft  220  is an amphibian in which a portion of the water-riding hull is resiliently mounted to deflect on landing. Alternatively, it can be said that aircraft  220  is an amphibian in which a portion of the water-riding hull moves with, or deflects with, a wheel of the landing gear. 
     In terms of the nose gear, nose gear  222  may be generally similar to nose gear  42 . Nose gear  222  has a torque tube  226  corresponding to torque tube  76  of aircraft  20 . However, torque tube  226  is in a fixed position corresponding to the extended position of the nose gear as seen in  FIG. 3 a    (and in  FIG. 10 a   ). Torque tube  226  does not have an input crank arm  78 , and is likewise not connected to a drive linkage such as connecting rod  188 . An input crank arm, analogous to input crank arm  78 , and having a distal end of the arm secured to fixed structure could be used in place of input arm  78  to secure torque tube  226  in the fixed position. Otherwise, nose gear  222  may be understood as being the same as, or substantially the same as nose gear  42 . 
     Considering the main gear, main gear assembly  230  is substantially the same as the main gear assembly of aircraft  20 . Main gear wheels  46  are resiliently sprung on a spring such as torque shaft assembly  232 . Torque shaft assembly  232  includes a laterally extending shaft  240  and respective left and right hand co-axial outer torque tubes connected at either ends thereof, (substantially the same as shaft  140  and tubes  142 ). As before, left and right hand lever arms  144  are connected to respective shock absorbers, or spring dampers,  146 . In contrast to the structure of aircraft  20  shown in  FIG. 4 a   , the main gear assembly of aircraft  220  does not a driven input arm  150 , but may have a fixed arm  250  secured in a position that may otherwise correspond to the “down” position of the main gear in aircraft  20 . Similarly, there is no transmission  100 , and no actuator  170  or its motor, worm drive linkages, or other features. Given that there is no nose gear transmission, parts  180 ,  182 ,  184 ,  186  and  188  may be omitted as well. Thus, as can be seen, the resilient torque tube arrangement of the main gear suspension is retained, without the drive and transmission. This may permit a reduction in aircraft weight and complexity. As such, the landing gear may be termed a “single position” landing gear since there is no active choice of more than one position. 
     Alternatively, the aircraft may have a combination of fixed gear and retractable gear. In an alternate embodiment, the aircraft may have a retractable nose gear, as in aircraft  20 , and fixed main gear as in aircraft  220 . In a further alternative, the aircraft may have a fixed nose gear as in aircraft  220  and retractable main gear as in aircraft  20 . 
     As can be seen, aircraft  220  is a fixed-gear amphibian aircraft. It has a fixed gear having three movably mounted water-riding hull portions—one at the nose, and two at the main gear sponsons. Those hull portions are resiliently mounted. In a further feature of that aspect, the water-riding hull portion is mounted forwardly or, and as a shield for, a first wheel if the fixed gear. The water-riding hull portion is mounted to move when the fixed gear deflects under load. 
     The amphibian aircraft having at least a first fixed landing gear. The aircraft has fixed main gear. It has a fixed nose gear. It has tricycle landing gear. All of the landing gear is, or are, fixed landing gear. The landing gear includes at least one resiliently mounted landing gear. Aircraft  220  has a first water riding member mounted to extend forwardly of the first fixed landing gear. The first water-riding member is movably mounted. The first water-riding member is mounted to deflect when the first fixed landing gear deflects. 
     There description is of a landing gear for amphibious aircraft  220 . The landing gear includes a wheel for rolling contact with a landing surface, and a deflector. The deflector defines a water-riding hull extending predominantly forwardly of the wheel. The deflector has an accommodation in which the wheel is mounted. The wheel extends partially downwardly proud of the deflector. The wheel and the deflector are mounted to move together, with the wheel protruding partially downwardly proud of the deflector. The landing gear is a single position landing gear. The wheel is resiliently mounted in a single position, and is resiliently movable in a range of motion in response to loading, the water-riding hull being correspondingly movable in co-operation with the wheel. The range of motion of the wheel has a first end of travel and a second end of travel. The first end of travel is a fully loaded position, and the second end of travel is an unloaded position. Immediately forward of the wheel the deflector has a centerline slope forwardly and upwardly of the wheel of less than 30 degrees from horizontal when the wheel is in the unloaded position. In the fully loaded position, immediately forward of the wheel the deflector has a centerline slope forwardly of the wheel that is tangent to horizontal. 
     The deflector forms one leg of a four-bar linkage. The wheel is carried in a seat defining at least one other leg of that four-bar linkage. The wheel has a foremost exposed portion and at the foremost exposed portion of the wheel a tangent to the wheel, when seen in side view has an angle of less than 45 degrees of arc from horizontal. The deflector has an opening formed therein, and the wheel protrudes through the opening. The opening has a first edge portion running along a first sidewall of the wheel, and an opposed second edge portion running along a second sidewall of the wheel. The deflector has a first side portion, a second side portion, and a keel portion therebetween, the wheel being mounted between the first side portion and the second side portion. The deflector extends at least three wheel diameters forward of the wheel. Immediately forward of the wheel the deflector has a centerline slope forwardly and upwardly of the wheel of less than 20 degrees from horizontal. The deflector has a sacrificial spine. The sacrificial spine is exposed and foremost, whereby in a gear-up landing the sacrificial spine is closer to the ground than any other non-wheel structure. 
     Aircraft  220  is an amphibious aircraft having a wheeled landing gear for landing on a landing field. The wheeled landing gear is a fixed gear having a range of motion between an unloaded position and a fully loaded position. The landing gear is mounted within, and extends partially downwardly proud of, a movable landing gear housing, or housings, that define water-engaging surfaces forwardly and laterally of the landing gear and, when the landing gear moves within the range of motion, the landing gear housings and the landing gear move together, with the landing gear extending partially downwardly proud thereof. One of the landing gear wheels is a steerable nose gear. The landing gear housing, or shell, has an external surface defining an external surface of the amphibious aircraft during both flight and water borne operation. The shell has an hydrofoil member mounted thereto. 
     It may be understood that the various aspects and features may be mixed and matched as may be appropriate. It may also be understood that the foregoing is not intended to be an exhaustive listing of aspects and features of the invention. These and other aspects and features of the invention may be understood with reference to the description which follows, and with the aid of the illustrations of a number of examples. 
     Various embodiments have been described in detail. Since changes in and or additions to the above-described examples may be made without departing from the nature, spirit or scope of the invention, the invention is not to be limited to those details.