Abstract:
A drainmast which releases water into an airstream traveling in a fore-aft direction includes a water-discharging exit on its underside for communicating with the airstream, a post-exit stage on its underside situated aft of the water-discharging exit, where the water-discharging exit is vertically offset downward from the post-exit stage. The drainmast also includes a fairing having a mounting flange and a mast projecting downward from the mounting flange, the mast having a main body with a window and a door fastened to the main body to close the window.

Description:
RELATED APPLICATION 
     This application claims priority under 35 USC 119(e) to U.S. Provisional Patent Application No. 61/485,674 filed on May 13, 2011. The entire disclosure of this provisional patent application is hereby incorporated by reference. 
    
    
     BACKGROUND 
     A drainmast can be installed on an aircraft to discharge water into the ensuing airstream. A drainmast can comprise a water-discharging exit communicating with the airstream, a draintube defining a water entrance into the drainmast, a heater for heating the draintube (to prevent water from freezing therein) and a fairing encircling internal regions of the draintube and the heater. If the drainmast also includes an exit-defining foot, it must usually also be heated to avoid ice from accumulating thereon. 
     SUMMARY 
     A drainmast design is provided with water-steering features that effectively and efficiently discharge water into the airstream. If the drainmast includes an exit-defining foot, some or all of these features can be incorporated thereinto. The water-steering features allow a drainmast and/or foot construction with smaller size, lighter weight, lower heating-power requirements, and/or decreased drag. 
    
    
     
       DRAWINGS 
         FIG. 1  shows an aircraft  100  with a drainmast  200  installed thereon. 
         FIGS. 2A-2H  show various views of the drainmast  200 , and  FIGS. 2I-2W  schematically show the drainmast&#39;s water-steering features. 
         FIGS. 3A-3G  show various views of a foot  300  of the drainmast and  FIGS. 3H-3K  show various views of the foot with a pedestal installed therein. 
         FIGS. 4A-4F  show various views of a fore draintube  400  mounted on the foot. 
         FIGS. 5A-5F  show various views of an aft draintube  500  mounted on the foot and  FIGS. 5G-5L  show various views of both draintubes mounted to the foot. 
         FIGS. 6A-6F  show various views of a heater  600  and  FIG. 6G-6I  show various views of the heater assembled with the foot and the draintubes. 
         FIGS. 7A-7Q  show various views of a fairing  700  and parts thereof. 
     
    
    
     DESCRIPTION 
     Referring now to the drawings, and initially to  FIG. 1 , an aircraft  100  is shown with a drainmast  200  installed thereon. The drainmast  200  is designed to discharge liquid into airstream A traveling in a fore-to-aft direction. The liquid can comprise, for example, potable water and/or gray water from the aircraft&#39;s plumbing system. 
     As shown in  FIGS. 2A-2G , the drainmast  200  has drain water entrances  201 - 202  and drain water exits  211 - 212 . When the drainmast  200  is installed on the aircraft  100 , the entrances  201 - 202  are connected to its internal drain lines. For example, the fore entrance  201  can be connected to a potable water drain line and the aft entrance  202  can be connected to a gray water drain line. The exits  211 - 212  are located on an underside  220  of the drainmast  200  and they communicate with the airstream A. 
     The illustrated drainmast  200  comprises a foot  300 , a draintube  400 , another draintube  500 , a heater  600 , and a fairing  700 . The foot  300  defines the exits  211 - 212  and the draintubes  400  and  500  define the entrances  201 - 202 . The heater  600  heats the draintubes  400  and  500  to prevent water from freezing therein, and also heats the foot  300  to prevent ice from accumulating thereon. The fairing encircles internal regions of the draintube  400 , the draintube  500 , and the heater  600 . 
     Fluid-steering features are provided on the drainmast underside  220  to efficiently and effectively introduce exiting drain water into the airstream A. While the illustrated drainmast  200  includes two exits  211  and  212 , this need not be the case. The fluid-steering and other features of the drainmast  200  can be used in the same or similar manner with single-exit and/or more-exits drainmast designs. 
     As shown schematically in  FIGS. 2I-2W , the fluid-steering features can include a post-exit stage  250 , a water-spraying step  260 , a water-kicking barrier  270 , and a water-escorting plank  280 . The stage  250  is situated aft of the exit area and vertically offset upward therefrom by the water-spraying step  260 . The water-kicking barrier  270  extends downward from the stage&#39;s aft end and the water-escorting plank  280  is cantilevered therefrom. Side rails  290  may extend downward from the lateral edges of the stage  250 . 
     Referring first to  FIGS. 2I-2L  (wherein only one exit  212  is shown), drain water leaving the exit  212  is positioned downward of the stage  250 . Assuming the airstream A has a vector substantially parallel with the stage level, the drain water is swept in a path below the stage  250  beyond the drainmast, as it passes over or off of the fore and aft corners of step  260 . ( FIG. 2I .) 
     Should some water creep upwards and engage the stage  250 , it quickly contacts the step  260 . The step-contacting water will migrate to the step&#39;s aft corner and will be carried off by the airstream A. ( FIG. 2J .) 
     If some stage-engaging water is not removed, this residual water is funneled downstream on the stage  250  and hits the barrier  270 . The barrier  270  kicks the water outward from the stage  250  so that it can be swept away by the airstream A. ( FIG. 2K .) While the barrier  270  can have a straight step-like construction, providing it with a V-shaped (with a pointed apex at its aft end) will also funnel water as it migrates aft so as to concentrate it centrally for efficient discharge at a single location. 
     And if any water climbs over the barrier  270 , it encounters the plank  280 . The plank  280  projects beyond the rest of the drainmast  200  and it has shape that aerodynamically encourages the airstream A to flow substantially evenly therearound. Thus, any water encountering the plank  280  is immediately escorted aft by the airstream traveling therearound. ( FIG. 2L .) 
     As shown in  FIGS. 2M-2P , the same series of fluid-steering events will occur with two exits  211  and  212 . 
     The drainmast  200  can incorporate each of the above-discussed fluid-steering features as they tend to complement each other in progression. However, depending upon the drainmast design, less than all of these features can be employed. For example, as shown in  FIGS. 2Q-2T , the step  260 , the barrier  270 , and the plank  280  can be used individually. And as shown in  FIGS. 2U-2W , the step  260  can be used with the barrier  270  without the plank  280  ( FIG. 2U ), the step  260  can be used with the plank  280  without the barrier  270  ( FIG. 2V ), and/or the barrier  270  can be used with plank  280  without the step  260  ( FIG. 2W ). 
     Referring now to  FIGS. 3A-3G , as was indicated above, the foot  300  defines the drainmast exits  211 - 212 . In the illustrated embodiment, the foot  300  includes passages  311 - 312 , the lower ends of which delineate the exits  211 - 212 . And as is explained in more detail below, the foot  300  also incorporates the fluid-steering features  250 ,  260 ,  270 , and  280  of the drainmast  200  (in the form of a deck  350 , a pulpit  360 , a bannister  370 , and a lip  380 , introduced below). 
     The foot  300  can comprise a ceiling  320  through which the passages  311  and  312  transverse. The topside of the ceiling  320  can host components adapted for fairing-connecting, heating, tube-holding and/or other purposes. For example, a fairing-connection tab  321  can be attached to the ceiling&#39;s fore edge, a heat-transfer island  322  can stand on an aft region, and a curved crest  323  can extend along its upper stern. Other components (such as the tube-holding pedestal  330  introduced below) can be connected or otherwise integrated into the foot ceiling  320 . 
     The underside of the ceiling  320  forms a prelude deck  340  fore of the exits  211 - 212  and a finale deck  350  aft of the exits  211 - 212 . A pulpit  360  is situated between the decks  340  and  350  and extends downward from ceiling  320 . The passages  311  and  312  extend transversely through the pulpit  360  whereby the exits  211  and  212  are located on the pulpit&#39;s bottom face  361 . At the fore end of the pulpit  360 , a ramp  362  forms a gradual transition between its bottom facel  361  and the prelude deck  340 . At the aft end of the pulpit  360 , a wall  363  forms a sharp stepped transition between its bottom face  361  and the finale deck  350 . If, for example, the pulpit&#39;s bottom face  361  is parallel with the decks  340  and  350 , the wall  363  can extend perpendicularly therebetween 
     A bannister  370  extends downward along an aft edge of the deck  350  and it can have a height approximately the same as that of the pulpit  360 . The bannister  370  can span across the deck&#39;s aft edge in straight path, but a more funnel-like form may enhance the efficiency of this fluid-steering feature. 
     In the illustrated embodiment, for example, the bannister  370  includes side sections  371  which angle inward and meet at an aft apex section  372  making a V-shape. This and other funnel-like forms will focus water towards the deck center to prevent lateral migration away from the deck  350 . And small water drips along the deck  350  will be collected and concentrated towards the apex section  372 , for efficient shedding from the foot  300 . 
     A converging lip  380  cantilevers outward from the aft edges of the finale deck  350  and thus extends beyond the crest  323  and the bannister  370 . As is best seen by referring briefly back to  FIGS. 2A-2B , the lip  380  also extends aft beyond the fairing  700 . The lip  380  has shape causing the airstream A to flow substantially evenly therearound. For example, the lip  380  can have a duckbill shape with smooth upper and lower surfaces that taper towards each other and smooth lateral edges that converge towards each other in the fore-aft direction. 
     Rails  390  can extend downward from lateral edges of the ceiling  320  to form side fences around the post-exit deck  350 . The rails  390  can also surround some or all of the prelude deck  340  and/or the pulpit  360 . The rails&#39; height can be slightly taller than that of the pulpit  360  and/or the bannister  370 . 
     As was alluded to above, the illustrated foot  300  incorporates the fluid-steering features  250 ,  260 ,  270 , and  280  of the drainmast  200 . Specifically, the deck  350  creates the post-exit stage  250 , the pulpit  360  causes the exit-stage vertical offset, the pulpit&#39;s rear wall  363  forms the spray-producing step  260 , the bannister  370  builds the water-kicking barrier  270 , and the lip  380  produces the water-escorting plank  290 . The rails  390  can function as the optional rails  290  of the drainmast  200 . 
     The foot  300  can be made any suitable metal (e.g., aluminum, stainless steel, titanium, alloys thereof), although copper and copper alloys may be preferred because of their heat-conducting and/or wear-enduring characteristics. The foot  300  can be formed in one piece by an appropriate manufacturing technique (e.g., casting and machining). That being said, non-metal foot materials (e.g., fiber-reinforced plastic) and/or plural-piece foot constructions are possible and contemplated. 
     The incorporation of efficient and effective fluid-steering features into the drainmast  200  allows a foot construction with smaller size, lighter weight, lower heating-power requirements, and/or decreased drag. For example, as is best seen by referring briefly back to  FIG. 2A-2C  and  2 H, the foot  300  does not span the entire length (i.e., fore-to-aft dimension) of the drainmast  200 , but instead only occupies non-fore regions. 
     The fore region of the drainmast underside  220  is formed by the fairing  700  (and particularly a bottom nose panel  731  introduced below). In the mid region of the drainmast  200 , only the very thin side edges of the prelude deck  340  and the walls of the pulpit  360  are laterally exposed. In the aft region of the drainmast, exterior surfaces of the crest  232  and bannister  370  are unsheltered by the fairing  700 . The lip  380  also extends beyond the fairing  700 , as this may be necessary to its water-escorting purpose. 
     Side rails  290 / 390  may still be necessary in many drainmast designs to prevent heavy discharge plumes from wrapping around the foot  300  and contacting the fairing  700 . However, the rails  290 / 390  may be made shorter in length (i.e., fore-aft dimension) and/or shorter in height (i.e., the up-down dimension). 
     Referring now to  FIGS. 3H-3K , a pedestal  330  can be attached to the foot  300 . The pedestal  330  can comprise a stand  331  and a heat-transfer block  332  attached to the stand  331 . In the illustrated pedestal  330 , the stand  331  is mounted on the foot&#39;s ceiling  320  just fore of the passage  321  and extends upward therefrom at a tilt in the fore direction. The stand&#39;s fore side  333  can be flat and the heat-transfer block  332  can be appended thereto. The aft side  334  of the stand  300  can be curved to cradle the draintube  400 . 
     The pedestal  330  can be made of the same or different material as the foot  300 , but preferably has strong heat-conducting characteristics. The stand  331  can be attached to the foot  300  by welding, brazing, or other suitable attachment technique. A pedestal  330  formed in one piece with the foot  300  (or a part of a multi-piece foot) is further feasible and foreseeable. 
     As shown in  FIGS. 4A-4F , the draintube  400  has an inlet adapter  401  at its top end which defines the the drainmast&#39;s entrance  201 . The draintube&#39;s outlet  411  extends through the fore passage  311  in the foot  300  and communicates with the drainmast exit  211 . The draintube  400  can lean tightly against the pedestal  330 , as the stand&#39;s aft side  334  conforms to its curved contour. 
     As shown in  FIGS. 5A-5F , the draintube  500  has an inlet adapter  502  at its top end which defines the drainmast entrance  202 . The outlet  512  of the draintube  500  extends through the fore foot passage  312  whereby it communicates with the drainmast exit  212 . A posing bracket  530 , with a circular aperture  531 , can be attached to the draintube  500  and project outwardly therefrom in the aft direction. 
     As shown in  FIGS. 5G-5L , when both the draintube  400  and the draintube  500  are mounted on the foot  300 , the drainmast entrance  201  communicates with the drainmast exit  211  and the drainmast entrance  202  communicates with the drainmast exit  212 . The inlet adapter  401  of the fore draintube  400  is attached to an aircraft drain line (e.g., a potable water drain line) and the inlet adapter  502  of the aft draintube  500  is attached to another aircraft drain line (e.g., a gray water drain line). And as is best seen by referring briefly back to  FIGS. 2A-2B , the adaptors  401  and  502  project above the fairing  700  so that they may extend into the aircraft fuselage for connection to the appropriate drain lines. 
     The draintubes  400  and  500  can be made of the same or different materials. But again, certain metals (e.g., aluminum, stainless steel, copper, titanium, alloys thereof) may be preferred because of their heat-conducting and/or wear-enduring attributes. They can be fixed to the foot  300  by welding, brazing, or any other appropriate affixing procedure. Draintubes  400 / 500  formed individually in one piece, in one piece with each other, in one piece with the pedestal  330 , in one piece with the bracket  530 , and/or in one piece with the foot  300  are achievable and acceptable. 
     The bracket  530  can be made of any suitable material and joined to the draintube  500  in any suitable manner. However, because the bracket  530  is primarily a posing part, high heat-conducting characteristics may not be necessary and could even be undesirable. Instead, a material encouraging heat to remain with the draintube  500  may be more advantageous. 
     As shown in  FIGS. 6A-6F , the heater  600  comprises a supply connector  610 , a return connector  620 , and a conduit  630  extending therebetween. The conduit  630  contains a resistantance-type heating element which is often best known under the General Electric tradename Calrod™. While other types of heaters may be used, a conduit-type heater can include continuous sections which are bent, wrapped, coiled, or otherwise shaped to closely conform with the to-be-heated components. The illustrated conduit  630  includes, for example, sections  631 - 637 . 
     As is shown in  FIGS. 6G-6I , section  631  extends down from the supply connector  610  to the pedestal  330 . Section  632  wraps around the heat-transfer block  332  of the pedestal  330 . Section  633  extends upward from the pedestal  330  along the fore draintube  400 . Section  634  bridges across the draintubes  400  and  500 . Section  635  extends downward along the aft draintube  500  to the foot  300  along one side of the posing bracket  530 . Section  636  coils around the island  332  in the foot  300 . And section  637  extends up from the foot  300  to the return connector  620  along the other side of the posing bracket  530 . 
     The connectors  610  and  620  are electrically connected to a power source onboard the aircraft  100  to thereby form an electrical path through the heating element in the conduit  630 . As is best seen by referring briefly back to  FIGS. 2A-2B , the connectors  610  and  620 , and the sections  631  and  637 , project above the fairing  700  so that they may extend into the aircraft fuselage for connection to onboard electrical lines. 
     As was indicated above, the fluid-steering features of the drainmast  200  allows for reduced heating-power requirements. As such, a separate heater for the foot  300  is not necessary. The pedestal&#39;s block  332  (which heater section  632  is wrapped around) and the foot&#39;s island  322  (which heater section  636  is coiled around) serve as heat sinks and sufficiently transfer heat to the otherwise ice-prone areas of the foot  300 . 
     It may be further noted that, except for the tube-briding section  634 , heater sections do not reside on lateral surfaces of the draintubes  400  and  500 . Specifically, for example, the section  631  and section  633  extend along the fore surface of the draintube  400  and section  635  and  637  extend along the aft surface of the draintube  500 . And is best seen by referring briefly back to  FIGS. 2A-2B , the tube-briding section  634  is situated above the fairing  700 . As such, the heater  600  does not widen the fairing-encircled span of the drainmast  200 . This contributes to a thinner profile, resulting in lower weight and decreased drag. 
     Referring now to  FIGS. 7A-7Q , the fairing  700  comprises a mounting flange  710  and a mast  720 . The flange  710  can include openings  711  for fastener receipt when mounting the fairing  700  to the aircraft  100 . A central slot  712  can be provided in the flange  710  for the draintube adapters  401 / 502  and the heater connectors  610 / 620  to extend therethrough. 
     The mast  720  extends downward from the flange  710  and forms a hollow  721  encircling the rest of the draintubes  400 / 500  and the heater  600 . Posing components can be strategically situated within the hollow  721  for properly positioning of the foot  300 , the draintubes  400 / 500 , and the heater  600  relative to each other and/or the fairing  700 . Specifically, for example, a slot  722  and/or a knob  723  can be posed within the fairing hollow  721 . 
     The fore region of the mast  720  forms its nose  730  and a rear region forms its tail  740 . A bottom panel  731  spans the nose  730  to form a fore region of the drainmast underside  220 . And as is best seen by referring briefly back to  FIGS. 2D and 2H , the remainder of the drainmast underside  220  is formed by the foot  300 . 
     The tail  740  includes a foot-accommodating profile, with cutouts  741 , an awning  742 , and a thin groove  743 . The cutouts  741  fit over the foot&#39;s crest  323  and the awnings  742  canopy over the crest  323 . The groove  743  receives fore and mid regions of the floor  320 . 
     The illustrated mast  720  comprises a main body  750  and a door  760 . The main body  750  has a window  751  which is situated on either its port or starboard side and which looks into the hollow  721 . In the illustrated fairing  700 , the window  751  has an open edge extending along the bottom of the body  750 . The door  760  closes the window  751  and sits flush with the main body  750 . Fasteners  770 , received in apertures  771 , are used to secure the door  760  to the main body  750 . 
     On the windowless side of the mast  720 , the main body  750  forms the cutout  741 , the awning  742 , and the groove  743 . On the windowed side of the mast  720 , the cutout  741  and the awning  742  are formed together by main body  750  and the door  760 , and the door  760  forms the groove  743 . 
     The door  760  can also include posing components on its inner surface. For example, the illustrated stub  761  works with the slot  722  to properly position the tab  321  of the foot  300  relative to the fairing  700 . And the illustrated knob  762  coordinates with the knob  723  on the main body  750  to sandwich the draintube bracket  530  therebetween. 
     The fairing  700 , the main body  750 , and/or or the door  760 , are constructed from a fitting medium, such one containing plastic, metal, and/or fiberglass. For example, they can be made from a fiber reinforced plastic by compression molding, resin transfer molding, and/or filament winding. Preferably, the main body  750  and the door  760  are each made in one piece. 
     With a one-piece fairing, there is no seam line between parts and thus no inherent weakness tempting mechanical failure. However, it is difficult to inspect interior components of the drainmast assembly after they are inserted into the hollow of a one-piece fairing. A two-piece fairing provides the advantage of after-insertion inspection, but this has traditionally come at the price of a seam line on the mounting flange. The doored design of the fairing  700  allows inspection of the interior components during assembly, without the compromising of a one-piece fairing  710 . 
     One may now appreciate that a drainmast design is provided with water-steering features that effectively and efficiently discharge water into the airstream. While the aircraft  100 , the drainmast  200 , the foot  300 , the draintube  400 , the draintube  500 , the heater  600 , and/or the fairing  700  have been shown and described with respect to a certain embodiment or embodiments, other equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this disclosure.