Abstract:
An airliner in which the wheel bogies of the main landing gear are stored one behind the other in a narrow, hollow keel at the bottom of the fuselage. The narrow keel replaces the usual voluminous hold under the passenger cabin. This decreases the cross-sectional area of the fuselage, to reduce aerodynamic drag. 
     One main strut of the landing gear angles forward during retraction, while the other strut angles backward. That allows the bogie tandem storage. It also requires swiveling a bogie as it enters the keel. The folding of the drag brace during strut retraction powers the swiveling mechanism. Elsewhere, the side brace folds and twists during retraction. 
     Dividing the main wing spar at the fuselage and passing only the bottom half under the cabin preserves the reduced hold volume. The decreased cross-sectional area allows the passenger cabin to be enlarged. It creates a “wide-body” supersonic airliner able to carry more passengers.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    An airliner design is disclosed which includes a greatly reduced hold volume under the passenger cabin. The bulky wing spar divides into thinner halves where it reaches the fuselage, passing over and under the passenger cabin, for a thin profile. 
         [0002]    Similar structure already exists. In the B-1 bomber, which lacks a passenger cabin, the flanges of the wing spar follow the contours of the fuselage, and the spar&#39;s web is a tall, thin bulkhead joining the flanges. See  FIG. 5  of Paper 730348, Transactions of the Society of Automotive Engineers, 1973, page  1138 . The goal there was weight savings. 
         [0003]    A variant of that is “How Different a Modern SST Would Be”, Aerospace America, November 1986, page 26. It proposes to divide the spar at the fuselage. The upper half of the spar is routed through the roof structure of the cabin. The lower half is part of the cabin floor. Wing loads are carried that way. A shallower fuselage is obtained. 
         [0004]    The reduction in the cross sectional area of our fuselage suggests widening it to carry more passengers. The usual voluminous hold under the passenger cabin is eliminated. A hollow keel is kept, just wide enough to store the wheel bogies of the main landing gear. The bogies are stored in tandem. This keeps the cross-sectional area of the keel at a minimum. No prior example of tandem bogie storage was found. 
         [0005]    To make tandem bogie storage possible, one landing gear strut retracts with a forward angle, and the other strut retracts with a backward angle. Retraction with an angle is seen in U.S. Pat. No. 5,000,400. Bogies must also swivel to enter the keel cleanly. Swiveling during retraction is found in U.S. Pat. No. 4,984,755 and many others. Our side brace twists while folding. In U.S. Pat. No. 3,086,733, the drag brace twists while folding. 
       SUMMARY OF THE INVENTION 
       [0006]    The first object of the invention is to significantly reduce the cross-sectional area of an airliner. The hold volume below the passenger cabin is greatly decreased. That is where the large wing spar normally passed through. The method begins by dividing the wing spar and re-routing the thinner branches over and under the passenger cabin. The method is already known in the art. We may add partial bulkheads to brace the fuselage&#39;s corners. The main problem is where to store the bulky wheel bogies of the landing gear now that the voluminous hold is gone. A substitute is found. 
         [0007]    Another goal is to make the changes useful to a civilian super-sonic airliner. In such an aircraft, the wings are usually too thin to house the wheels of the landing gear. The solution is to retract the wheel bogies of the landing gear into a narrow, keel-like volume just under the passenger cabin. The narrowness is for reduced cross-sectional area. This decreases drag. It&#39;s the smallest replacement possible for the hold volume obviated by the use of a divided spar. Thus, retracting the landing gear involves placing the wheel bogies one behind the other in the narrow keel. During retraction, one strut angles sharply forward, and the other strut angles sharply backward. Therefore, the axis of retraction for a strut is skewed relative to the fuselage. But during landing, the bogie pointed straight ahead; it was “toed-in” relative to the re-traction axis. A mechanism is added to swivel the wheel bogie back to parallel to the retraction axis. Then the bogie avoids bottoming one wheel too soon in the keel at the end of the strut&#39;s retraction. 
         [0008]    The narrow keel preserves the large reduction in the cross-sectional area of the fuselage. That decreases the supersonic wave drag. Thus, the passenger cabin can be widened to carry more passengers. The overall intent is to achieve a “wide-body” supersonic transport aircraft design with performance approaching that of existing narrow-body Mach 2 airliners. Calculations will be presented at the end to support this view. 
     
    
     
       BRIEF DESCRIPTION OF THE VIEWS 
         [0009]      FIG. 1  is a transverse elevation of the cabin of a wide-body airliner. 
           [0010]      FIG. 2  is an oblique elevation side view of a supersonic airliner. 
           [0011]      FIG. 3  is a ¾ underside view of an extended main landing gear. 
           [0012]      FIG. 4  is an elevation of the bogie orientation scissors in the position for landing the aircraft. 
           [0013]      FIG. 5  is an elevation of the bogie orientation scissors in the position of landing gear retracted. 
           [0014]      FIG. 6  is a side elevation of the composite parts in  FIGS. 4 and 5  plus a slide rod. 
           [0015]      FIG. 7  is a side elevation of the parts in  FIG. 4  fully compressed during a landing. 
           [0016]      FIG. 8  is a plan phantom view from above of the retracted main landing gear. 
           [0017]      FIG. 9  is a cross-section of the side brace ball joints and an elevation of the side brace links. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    A limitation on the speed of an aircraft is the cross-sectional area which the aircraft presents to the airstream. The larger this area, the greater the profile drag at subsonic speed, or the greater the wave drag when supersonic. One of the things which increases cross-sectional area is the wing spar where it crosses the fuselage. The spar is a deep structure, for stiffness. In airliners the spar can&#39;t very well cross the passenger cabin, so it passes under it instead. This creates a large hold volume handy for storing the landing gear. We eliminate the large hold by dividing the wing spar and routing the thinner halves over and under the passenger cabin. The fuselage becomes slimmer. But this is already known in the art. We build on it for our purposes. Therefore, the text begins with a different set of details about the fuselage. Then a landing gear which is essential to the invention will be shown. 
         [0019]      FIG. 2  shows a supersonic airliner design which benefits from the invention. The airliner design is inspired by the Mach 2 Concorde, which was in airline service for two decades. Our general layout is similar to Concorde&#39;s. The first differences are the wide-body fuselage  14  which will house more passengers, and the narrowed waist of fuselage  14  to reduce wave drag. But the second item is already known in aerodynamics as area ruling, and will not be further discussed. The invention features a narrow keel  7  below fuselage  14 . Keel  7  comprises an empty volume in which the wheels of the main landing gear will be stowed. It is desired that the sum of keel  7 &#39;s cross-sectional area plus that of passenger cabin  14 , is comparable to Concorde&#39;s oval fuselage. The ultimate goal is to approach Concorde&#39;s performance. 
         [0020]      FIG. 1  is a cross section of the fuselage  14  showing passenger cabin volume  16  and keel  7 . Cabin  16  contains passenger seat  2  plus six others in the row reaching across to a total of seven (compared to Concorde&#39;s four.) Keel  7  encloses main landing wheels  8  and  9 . There are more wheels behind them, shown in a later figure. Wheels  8 ,  9  et al are held by beam  6  which is ultimately connected to main landing gear strut  3 . The hole at the right end of strut  3  can turn on a pivot, shown later, which is attached to wing  4  structure. Strut  3  was retracted by hydraulic cylinder  18 . The whole aircraft has nearly bilateral symmetry. On the other side of the aircraft, strut  10  is also shown in the retracted position. The two bends in strut  10  enable it to squeeze through the limited space below passenger cabin volume  16 . Strut  3  is the mirror image of strut  10  and also has a reverse bend. Strut  3  may fit between the floor joists, if any, in cabin floor  1 , and will position the bulky wheels  8 ,  9  substantially below cabin floor  1 . 
         [0021]    When extended by hydraulic cylinder  13  for landing, strut  10  would be in a position indicated as  11 . An engine nacelle (omitted) would normally be just outboard of position  11 . Hydraulic cylinder  13  is housed in partial bulkhead  15  which extends into the cabin volume  16  without, however, intruding into aisle  16 &#39;s walking space. Bulk-head  15  also braces fuselage corner  14  against flexing when the shock load of landing is carried in part to the roof portion of the fuselage. Attention now turns to the main landing gear. 
         [0022]    In  FIG. 3 , sheet metal is removed around wing spar  21  for visibility. The conventional parts of the landing gear are listed: 
         [0023]    Strut  3  pivotably mounted on wing spar  21 ; drag brace  5 ,  26 ;
       side brace  33 - 35 ; lower strut  29 , which can slide upward relative to strut  3  to absorb the mechanical work of landing impact; A-frames  30  and  31  as the alignment scissors for lower strut  29  to strut  3 ; beam  6  pivoted on lower strut  29  and carrying wheels  8 ,  9  et al, thus constituting a main wheel bogie  28 .       
 
         [0025]    Lower strut  29  could be of smaller diameter than strut  3 , and slide inside it. That is the usual arrangement. But here it is drawn as sleeve  29  wider than strut  3  and sliding over it. The reason will be given later. 
         [0026]    Door  42  in keel  7  will swing downward during retraction, revealing the keel  7  volume to stow bogie  28 . Door  42  pivots on hinges  43  when pushed by actuator  44 . 
         [0027]    In  FIG. 3 , the main landing gear is extended for landing. Accordingly, bogie  28  is tracking in the same direction as edge  7  of the keel, which is equivalent to the heading of the aircraft. Of course, the aircraft and bogie  28  are at a high angle of attack, for landing, but the track of the wheels is approximately aligned with the landing strip. Axis  22  of the pivot for drag brace  5  also points straight ahead, so that drag brace  5  can absorb fore-and-aft loads. Side brace  33 - 35  conventionally absorbs side loads. Thus, landing is completely ordinary. It is largely ignored hereafter. Landing gear retraction after takeoff is the big item. 
         [0028]    The bogies of conventional landing gears may swivel, for crosswind landings, and they can level themselves, to land flat on the runway. Our gear has the same two freedoms. Thus, it&#39;s tricky to insert bogie  28  cleanly into very narrow keel  7  at the end of landing gear retraction. Bogie  28  has to be oriented carefully. It&#39;s the most important single operation for the invention. 
         [0029]      FIG. 3  shows the landing gear right after takeoff. The side brace has two links  33  and  35  and a hinge  34 . There are ball-and-socket joints  32  and  41 . Retraction starts with a pull from hydraulic cylinder  37 &#39;s piston rod upon link  35 . Side brace  33 - 35  will break at hinge  34 , unlocking strut  3  from the vertically extended position. Simultaneously, rod  36  (the piston rod of hydraulic cylinder  18  in  FIG. 1 ) will pull diagonally on strut  3  in  FIG. 3 . Strut  3  would start to move upward and inward. That would be the beginning of main landing gear retraction. Mostly conventional so far. 
         [0030]    However, axis  23  of strut  3 &#39;s pivot points not straight ahead, but in an outward direction. This is so that strut  3  will angle forward when it retracts upward. Bogie  28  will then enter the front part of keel  7 . This is visible in  FIG. 8 . Simultaneously, strut  10  on the other side of the aircraft would angle backward during retraction. Then its bogie  85  (seen in  FIG. 8 ) would lie in tandem with bogie  28  within keel  7 . This is the first goal of the invention. The details of achieving it follow. 
         [0031]    Returning to  FIG. 3 , it&#39;s expected that drag brace  5 ,  26  will shorten during retraction because axis  22  is on the inside of axis  23 . Pushed by hydraulic cylinder  24 &#39;s piston rod, drag brace  5 ,  26  will break&#39; at joint  25 . The end result is seen in  FIG. 8 . Drag brace  5 ,  26  is fully broken. Lower strut  26  has turned downward, pushing on slide rod  27 . The use of that will be shown later. 
         [0032]    In  FIG. 3 , the difference from usual landing gear retraction will appear as strut  3  turns about axis  23  in order to move upward and forward. Bogie  28  must then start to swivel to its left. That is because wheels  8  and  9  were “toed-in” relative to axis  23  when the gear is down as shown. The toe-in means that wheel  8  would be too high when bogie  28  reached keel  7 . Wheel  8  would hit the keel ceiling  45  before the other wheels were fully housed in keel  7 . Therefore, bogie  28  must swivel left during retraction. 
         [0033]    It is noted that U.S. Pat. No. 5,000,400 neatly sidesteps the problem by making the strut pivot (his trunnion  92 ) point partly toward the ground. That is seen in his  FIGS. 2 ,  13 , and  15 . It counteracts his wheel truck&#39;s toe-in. However, his partly downward trunnion  92  would load his wing spar sideways during landing. We chose a different solution. As a result, our strut  3 &#39;s pivot axis is level with the wing. 
         [0034]      FIG. 4  shows the scissors made by A-frames  30  and  31  pointing straight ahead as in  FIG. 3 . This is the position for landing the aircraft. It remains the same right through the next takeoff. The alignment is established by stud  46  being located in the top part  48  of angle groove  47 . Stud  46  is part of A-frame  30 , and angle groove  47  is part of A-frame  31 . That sets the alignment of sleeve  29  to strut  3  for landing. How stud  46  got to where it is will be shown in  FIG. 6 . 
         [0035]      FIG. 5  illustrates the position of the components when the landing gear will be fully retracted. Now stud  46  is at the bottom of the angled part of angle groove  47 . A-frame  30  has been forced to turn. It turned sleeve  29  with it. Sleeve  29  in  FIG. 3  carries bogie  28 , so that is how bogie  28  is swiveled for retraction. 
         [0036]      FIG. 6  shows that the motions of stud  46  are obtained by the action of slide rod  27 .  FIG. 6  is a side view of the components and is a composite drawing which recaps both  FIGS. 4 and 5 . Thus, there are two images of A-frame  30 . The top image of A-frame  30  corresponds to  FIG. 4 : Stud  46  is in the high position within angle groove  47 . The bottom image of A-frame  30  corresponds to  FIG. 5 , with stud  46  in the low position within angle groove  47 . Stud  46  was pulled up by the bottom loop  62  of slide rod  27 , or else pushed down by the heel  63  of the slot in slide rod  27 . Thus, the whole operation is controlled by the motions of slide rod  27 . They correspond to the two positions of bogie  28 . The position for landing and takeoff was seen in  FIG. 3 . The position when the landing gear is retracted is seen in  FIG. 8 . 
         [0037]      FIG. 8  illustrates the desired end of landing gear retraction. Viewed from above the aircraft, passenger cabin  16  and its contents are omitted, including floor  1  from  FIG. 1 . The outlines of fuselage  14  and keel  7  remain. Wing skin is omitted for visibility. The direction of flight is to the right. Strut  3  has fully retracted by pivoting about axis  23 , which is fixed to wing spar  21 . Strut  3  is now substantially flat in the wing, and the aircraft is in flight. 
         [0038]    Reviewing previous material, the offset of drag brace hinge  22  to strut  3 &#39;s pivot axis  23  has caused drag brace  5 ,  26  to shorten during strut  3 &#39;s retraction. Drag brace  5 ,  26  broke at hinge  25 , and the brace&#39;s lower half  26  turned on its pivot at strut  3 . Slide rod  27  was pushed toward stud  46 , causing the action resulting in  FIG. 5 . That is how bogie  28  was “steered” for retraaction. Viewed in a different way, in  FIG. 8  bogie  28  is co-planar with axis  23 . Additionally, beam  6  now had to dip to a new angle for bogie  28  to enter keel  7  cleanly. Its former alignment, the perpendicularity of beam  6  to sleeve  29  in  FIG. 3 , had to be altered to “droop” wheels  8  and  9 . In  FIG. 8 , that was accomplished by a push from hydraulic cylinder  82 . It&#39;s just an adaptation of a bogie beam damper. 
         [0039]    The end result of all these operations is to place bogie  28  inside keel  7  cleanly. Bogie  28  is now substantially aligned with keel  7  in horizontal and vertical planes. The other landing gear strut  10  went through similar operations and ended up fully retracted in  FIG. 8 . It caused bogie  85  to enter keel  7  aligned with it too. This accomplishes one goal of the invention: Bogies  28  and  85  stored in tandem allow keel  7  to be much narrower than fuselage  14 . 
         [0040]    However, the topic of landing gear retraction is not exhausted. Next is the issue of side brace  33 - 35  folding as strut  3  retracts. It&#39;s a little involved. Side brace links  33  and  35  formed a “V” as strut  3  angled forward while it moved upward. Pivots  32  and  41  are ball joints to allow this motion. But joint  34  is a simple hinge, so it had to twist a lot from its orientation in  FIG. 3  to let links  33  and  35  form the “V” seen in  FIG. 8 . These items are seen in more detail in  FIG. 9 . 
         [0041]      FIG. 9  shows ball joints  32  and  41  in cross section and links  33  and  35  in elevation. Ball joint  32  is connected to strut  3 , and ball joint  41  is connected to spar segment  40 . The long links  33  and  35  appear foreshortened because they are seen in the length of the “V” in  FIG. 8 . In  FIG. 9 , hinge  34  has almost closed. Axis  91  of hinge  34  makes an angle of 70 degrees to former axis  92  from  FIG. 3 . Thus, the folding of side brace  33 - 35  during retraction is a three-dimensional affair. Links  33  and  35  had to twist considerably to reach the position seen in  FIGS. 8 and 9 . The twist was started when hydraulic cylinder  37  of  FIG. 3  pulled on ball joint  39 , which is off-center on link  35 . In  FIG. 9 , the ball of ball joint  39  is seen to be considerably off-axis to the centerline of link  35 . (The centerline is not shown, but would run down the middle and the length of link  35 .) Of course, the fully twisted link  35  has turned ball joint  39  seventy degrees beyond its orientation in  FIG. 3 . The pull on ball joint  39  would have ceased long before ball  39  reached the point seen in  FIG. 9 . Otherwise, continued pull would have stopped the twist. A brief pull from actuator  37  in  FIG. 3  will start the twisting while it breaks the brace. Once started in  FIG. 3 , the rest of the twist and the break should follow naturally as links  33  and  35  continue to fold toward the end seen in  FIG. 8 . 
         [0042]    The twisting folding of side brace  33 - 35  is largely anticipated by the twisting folding of brace  23 ,  24 ,  31  of U.S. Pat. No. 3,086,733. The progression of the folding is seen in his  FIGS. 2-4 . His  FIG. 2  corresponds to our  FIG. 3  (gear down) and his  FIG. 4  corresponds to our  FIG. 8  (gear retracted.) His  FIG. 3  shows an intermediate position during twisting folding. The most significant difference is that his hydraulic cylinder  38 , which breaks the brace, pulls at the center of his hinge  31  (His  FIG. 5 .) Apparently the twisting will start automatically. Our method is a more positive beginning to the action. A lesser difference is his double articulate joints  26 - 27  and  32 - 33  instead of our ball joints  32  and  41 . His may be //easier to manufacture. They are considered equivalent in the Claims. 
         [0043]    In  FIG. 9  the large open arc in ball socket  32  is only the clearance groove for ball post  93 . Ball socket  32  can enclose the ball much more than the cross section suggests. The same thing with ball socket  41 . Ball socket  32  with its clearance groove is seen more completely in  FIG. 8 . The clearance groove is partly seen in  FIG. 3 . Its orientation should let link  33  start to twist when the brace breaks. Of course, the shape of the clearance grooves must allow the twisting to synchronize with the folding. This concludes the discussion of landing gear retraction. Re-capping, only the half of the main landing gear on the left side of the aircraft, namely strut  3 , its braces and its bogie, was examined in detail. The operations on strut  10  and its equipment were assumed to be similar. 
         [0044]    In  FIG. 7 , the scissors made by A-frames  30  and  31  close up during landing. Sleeve  29  rides upward over the end of strut  3 , absorbing the landing impact through conventional oleo action. The shock of landing, however, might cause A-frames  30  and  31  to bounce in and out of the engagement seen in  FIG. 4 . In other words, stud  46  could slip out of the top part of angle groove  47 . Then the bogie would swerve, a problem. In  FIG. 7 , spring  61  tension should prevent that by pulling A-frames  30  and  31  together. Stud  46  will stay in the vertical part  48  of angle groove  47  in  FIG. 4 . 
         [0045]    At the same time, stud  46  is at the midpoint of slide rod  27  in  FIG. 7 . Slide rod  27  has no effect there. Landing should proceed without incident. This concludes the discussion of landing gear operation. The text reverts to the fuselage modifications. 
         [0046]      FIG. 1  shows the airframe&#39;s adaptation to the landing gear. Strut  3  and strut  10  have a certain thickness for which room is found at the bottom of the fuselage. The same goes for cabin floor  1  under passenger cabin volume  16 . In addition to that, upward loads from wing  4  during flight and when landing must be transmitted in part along the bottom of fuselage  14 . (Keel  7  is omitted completely from this discussion.) Thus, three types of structural members will compete for the space below passenger cabin volume  16 . First in consideration is the loads from wing  4 . 
         [0047]    In  FIG. 3 , wing spar  21  divides into two thinner portions  38  and  40  where it meets the fuselage. Numerals  21 ,  38  and  40  point to the suggested cross sections. Spar portion  40  continues horizontally to the left. As seen in  FIG. 8 , spar portion  40  crosses the width of fuselage  14 . It thereby transmits some of the wing loads. Secondary spar  81 ,  83  supports the pivot  22  for drag brace  5 ,  26  and also crosses fuselage  14 . Similarly with secondary spar  84 ,  86 . These, then, are the main load-carrying members at the bottom of fuselage  14 . Between them is enough space to store landing gear struts  3  and  10  in  FIG. 8 . There&#39;s enough room for drag brace  5 ,  26  and side brace  33 ,  35  beside strut  3  too. Similarly with strut  10  and its braces. Thus, two out of the three types of load-bearing members are accommodated. 
         [0048]    Strut  3  or  10  is about the same thickness as spar  40 . If a strut can fit under the passenger cabin, so can spars  40 ;  81 ,  83 ; and  84 ,  86 . In  FIG. 1 , struts  3  and  10  do fit under passenger cabin  16 , so there was no need to draw the spars. It&#39;s understood that they fit too. That leaves cabin floor  1 . It is drawn symbolically as an un-differentiated thickness. Floors are usually joists spaced apart and supporting a thin slab to walk on. Our spars could double as joists, and the slab (not shown specifically) could be honeycomb sandwich panels resting on the spars. Thus, it appears that spars, struts, and cabin floor members can all fit under passenger cabin  16 . 
         [0049]    The wide, flat roof of fuselage  14  will bulge from cabin pressurization, and buckle under aerodynamic loads. A solution from the past is applied. Stays  17  like from old fire-tube boilers strengthen the long walls by tying them together. Stays  17  should fit between the seat backs of passenger seats to avoid cramping the passenger cabin volume. 
         [0050]    Further bracing of the cabin structure is supplied by floor-to-ceiling partial bulkheads  15  and  20 . Too, vertical dividers  19  of the overhead luggage racks can stiffen the upper corners of fuselage  14 . Also, thin fillet  12  below the passenger&#39;s knees braces a lower corner without cramping the legs too much. These additions strengthen the structural loop around cabin volume  16  which starts with spar branch  38  of  FIG. 3 . In  FIG. 1 , partial bulkhead  20  turns the right side of fuselage  14  into a more rigid whole. Then the bending load from wing  4  is transmitted to the cabin roof where bulkhead  20  ends. In other words, along an angle similar to that made by the slanting of hydraulic cylinder  18 . This is a more efficient way to transmit the loads than to route them all the way around the perimeter of the rectangular envelope of fuselage  14 . 
         [0051]    Still, nothing herein prevents a drastic rounding of the fuselage upper corners such as  14 , in order to decrease fuselage cross-sectional area and therefore drag some more, at the cost of some headroom. 
         [0052]    Continuing the process, partial bulkheads  15 ,  20  could be duplicated at other cabin stations crossed by spars such as  81 ,  83  and  84 ,  86  of  FIG. 8 . Spar  81  is seen interrupted at slide rod  27 . Spar  81  would have to become shallow to squeeze over sleeve  29  and join spar segment  83 . The same thing would happen to spar segment  84  passing over bogie  85  to join spar segment  86 . 
         [0053]    Two short topics follow.  1 ) In  FIG. 8 , bogies  28  and  85  stored in tandem by no means fill the whole length of keel  7 , which stretches fore and aft for streamlining. The extra volume can store passenger luggage.  2 ) In  FIG. 2  the wide flat roof of fuselage  14  extends backward to the tail, where a control surface  50  is a natural addition. Control surface  50  trims the aircraft at low speeds, but reverts to streamline when the center of lift moves aft during supersonic cruise. It avoids having to pump fuel to a balancing tank to level the aircraft. 
         [0054]    Returning to the landing gear, lower strut  29  in  FIG. 3  is in the form of a sleeve  29  which is wider than strut  3 . This is contrary to usual practice. For instance, in  FIG. 2  of U.S. Pat. No. 4,720,063, lower strut  24  is thinner than upper strut  22 . In  FIG. 2  of U.S. Pat. No. 4,984,755 lower strut  5  is thinner than upper strut  1 . Our reason for inverting the normal arrangement is found in our  FIG. 1 . Strut  10  is relatively thin so it can pass under passenger cabin  16  and still leave a little thickness from cabin floor  1  above strut  10  for the passengers to walk on. That was part of how the cross-sectional area of fuselage  14  was kept to a minimum, for lower drag losses. But certain consequences follow. Returning to  FIG. 2  of U.S. Pat. No. 4,720, 063, it is seen that lower strut  24  is nearly as thick as upper strut  22 . In  FIG. 2  of U.S. Pat. No. 4,984,755, lower strut  5  is nearly as thick as upper strut  1 . The implication is that the lower struts must be relatively thick for enough strength to support the bogie or wheel. Since our struts  3  or  10  are already thin, it&#39;s difficult for an even thinner strut sliding inside strut  3  or  10  to avoid bending under the landing shock. Sleeve  29  solves the strength problem by being wider than strut  3 . Also, since sleeve  29  can be the stronger of the two, it might be made of titanium, which is only 57% as heavy as steel, a significant weight saving. Still, some other, thinner lower strut, in the form of a solid rod, is not excluded from the Claims, because of continuing advances in metallurgy. 
         [0055]    A fringe benefit would be that, in  FIG. 8 , minor spars  81 ,  83  wouldn&#39;t need to flatten so much to squeeze over lower strut  29  if it was thinner than strut  3 . 
         [0056]    An overview. It is apparent from the cross section seen in  FIG. 1  that the aircraft is close-cowled. That is, not only is the landing gear squeezed into a minimum volume (keel  7 ), but so is passenger cabin space  16 . The low ceiling, partial bulkhead  15 , stay  17  and fillet  12  are all intrusions into the passenger area which decrease passenger comfort. On the other hand, flight time at Mach 2 on overseas routes would be half of the time in a subsonic airliner. The two realities could largely offset each other. The passenger seating in  FIG. 1  is the maximum row size. The pinched waist of fuselage  14  for area ruling seen in  FIG. 2  means that there would be fewer than seven seats across. Say  5  seats; but there is room for more seats in the tail, which is no longer too narrow. Similarly up front, because the crew didn&#39;t get more numerous. The seating ratio to Concorde&#39;s can be kept at 7:4. Then passenger seat miles rise by 75%, and per-capita operating costs drop by 3/7=43 per cent. 
         [0057]    A side benefit of  5 -across seating is that the now-isolated window seats can be bigger, for large passengers. 
         [0058]    We end with a long segment to see how close the invention comes to reaching its stated goals. It starts with measuring the cross section of our wide-body fuselage, then comparing to Concorde&#39;s fuselage&#39;s cross section. The widths of the fuselages scale as 7:4, the ratio of seats across in the cabin. This sets the dimensions of the drawings for comparison. A cross section of Concorde&#39;s fuselage is  FIG. 22  of Paper 912162, Society of Automotive Engineers (“SAE”). Comparing our  FIG. 1  to that  FIG. 22 , it is found that our  FIG. 1  has 50.5% more cross-sectional area. A sizeable enlargement. A downward adjustment is the elimination of Concorde&#39;s high-drag landing gear fairing, shich costs 10% of payload (Section 6.4, SAE Paper 912162.) Our keel  7  is the most streamlined component of the aircraft. Subtracting Concorde&#39;s landing gear fairing&#39;s area from our nominator lessens the cross-sectional area increase represented by our  FIGS. 1  to 39.5%. 
         [0059]    The fuselage creates only part of the profile drag. Wings, tail, and nacelles also contribute. Measuring those drags uses the frontal view of Concorde in the lower Figure on page  83 , JANE&#39;s All The World&#39;s Aircraft, 1978-79. It is found that its fuselage constitutes some 27.2% of the total cross-sectional area. Our wider fuselage then represents a (0.272)(39.5%)=10.7% increase in form drag. 
         [0060]    A further penalty is that our wide-body fuselage adds some surface to the wetted area of the aircraft. Another comparison reveals a 19% increase by our passenger cabin plus keel over Concorde&#39;s fuselage plus landing gear fairing. Adding the tail, nacelles, and the wings to the denominator of a comparison ratio, our 19% increase corresponds to only 2.8% more total surface, therefore friction drag. 
         [0061]    Subsonic form drag computed above becomes wave drag past Mach 1. This makes up 37.5% of total drag at cruise. ( FIG. 2  of SAE Paper 751056, also in 1975 SAE Transactions, page 2944.) Friction drag adds a 32.5% share. Thus, only a fraction of the losses found so far would apply: ((37.5)(10.7)+(32.5) (2.8 ))/100=4.94% greater total drag. It is seen that the graph,  FIG. 2  of SAE Paper 751056 is the main basis for the analysis. 
         [0062]    Additionally, there will be two weight increases. These will necessitate more wing lift, which creates more drag. The first weight increment is caused by 75 more passengers.&#39; At an average weight of 160 lbs each, that is (75)(160)=12,000 lbs. The second weight increment is caused by the wide fuselage. It is roughly proportional to the increase in the aircraft cross-sectional area computed above of 10.7%. Concorde empty weight is 173,500 lbs (JANE&#39;S, page 84). Structure weight can be approximated by subtracting the weight of things which don&#39;t change: Four engines at 7465 lbs each (JANE&#39;s, page 695), totaling 29,860 lbs; two nacelles, whose volume proportion of total bulk is 10.4 percent, giving some 10,400 lbs estimated; landing gear 17,350 lbs (ten percent of empty weight, an estimate); air conditioning, fuel tanks or liners, windows, avionics, instrument panel, wiring, fittings, nose droop mechanism: 15,000 lbs estimate. Structure weight of Concorde is then approximately 173,500−29,860−10,400−17,350−15,000=100,890 lbs. Structure weight goes up by (10.7%)(100,890)=10,790 lbs. Total weight increment is 12,000+10,790=22,790 lbs. 
         [0063]    Concorde maximum takeoff weight is 400,000 lbs (JANE&#39;s, page 84). The per cent increase in gross weight is 22,790/400,000 32 5.7%. That translates to greater wing lift required, which means more drag. Using again  FIG. 2  from SAE Paper 751056, the remainder is drag due to lift, plus wave drag due to lift, which add up to 30% of total drag at Mach 2.0. The net drag increase from the wing is (30%)(5.7%)=1.71%. 
         [0064]    Grand total drag increase is then 4.94%+1.71%=6.65%. Using strict proportionality, the new cruise speed is Mach 2−(2)(0.0665)=1.867. That&#39;s how close we can come to existing Concorde performance without other changes. We note that a representative of the engine manufacturer implied that a Mach 1.8 cruise is acceptable (Aviation Week &amp; Space Technology, Jan. 1, 2000, page 56.) 
         [0065]    At Mach=1.867 cruise speed, Concorde&#39;s range of 4,000 miles would drop by 6.65% to our 3,734 miles. Range can be increased by adopting the “B” wing design (briefly described in SAE Paper 800732 also in SAE Transactions, 1980, page 2276.) The lift/drag ratio is 7.8, compared to Concorde&#39;s 7.3 (SAE Paper 892237, page 3.) It is an improvement of 6.8%. When it is applied at the 30% wing drag fraction of total drag, or 2.04%, speed and range go back up by that amount to 3,820 miles and Mach=1.907. It&#39;s not much trouble to incorporate the “B” wing: Our wing structure, for instance the spars in  FIG. 8 , is different anyway. Gas mileage is (3,820)/4,000=95.5% of what it was. Thus, with the help of the “B” wing, a wide body Mach 2 airliner design is nearly achieved. The real payoff remains, 75 more passengers, which reduces the per-capita operating cost by (43%)(0.955)=41 percent. 
         [0066]    Standard construction in aluminum was assumed, but the growing use of lighter and stronger modern composites would reduce weight and allow a thinner wing, for higher cruise speed and more range. Advances in engine design were not considered, although they would be required at least to meet FAR Part  36  noise limits. Still, a proposal known as the Mark 622 was some simple changes to the Olympus 593 engines from the manufacturer and reported in previouslycited SAE Paper 800732, also in  1980  SAE Transactions. On pages 2276, 2278, and 2280-83, small enlargement of the first three stages of the low pressure compressor gave airflow growth of 15 or 20% (changes 2 and 7 on page 2282.) The 20% increase, after some small compression, was routed directly to the jet pipe as bypass flow, giving a 4% drop in fuel use. The 15% increase had the advantage of requiring only a small increase in low-pressure turbine diameter (using paragraph 5, page 2282.) It was also notionally retrofittable in the existing aircraft. 15% extra flow going to bypass would give a 3% drop in fuel use. Range would be back up to 3,820+(0.03)(4,000)=3,940 miles. Thus, practically unchanged for an airline. That, and cruise speed of Mach 1.9, are the closest approach to Concorde performance without completely new engines. Savings in per capita operating costs are back up to (43%)(0.985)=42.3 percent. 
         [0067]    Housekeeping items follow:
   a) The outline of fuselage  14  in  FIG. 8  ignores the pinched waist for area ruling of  FIG. 2 . This is so that a proper comparison of the widths of narrow keel  7  versus the typical width of fuselage  14  can be made in  FIG. 8 . In a real aircraft, the greatest indentation of the pinch would be near the axial station of sleeve  29 .   b) In  FIG. 1 , drag brace  5  is drawn as straight, but that&#39;s only to avoid obscuring the right-most end of strut  3 . Brace link  5  could have a shallow upward bend in it too.   c) The proposed “B” wing  4  in  FIG. 2  was planned to have moveable leading-edge slats, for better low-speed lift. These weren&#39;t shown in  FIG. 2  because they are well known in the art.   d) A Concorde-type bogie comprising four wheels in two pairs was pictured throughout. Other bogie styles can work: Three wheels in a single column like in  FIGS. 13-14  of U.S. Pat. No. 5,000,400. Then our keel  7  would be even smaller, for less drag.   
 
         [0072]    The scope of the invention can be found in the appended Claims.