US 3675582 A
A high speed mass transportation system, in which a train unit rides in an arcuately concave, narrow guideway and is aerodynamically supported on airfoils conforming to the arcuate form of the guideway. The center mass of the vehicle is below the center of radius of the guideway, which provides a self-stabilizing and automatic banking action in high speed turns, so that passengers are not subjected to lateral accelerations. The airfoils are spaced several inches above the guideway at cruising speed, so that the surface finish of the guideway is not unduly critical and cost is minimized. Retractable wheels are provided for supporting the train unit at low speeds and on flat surfaces. Propulsion may be by means of direct thrust, such as a propeller, or by electrical drive means, such as a linear induction motor.
Claims available in
Description (OCR text may contain errors)
United States Patent Girard et al.
[ 51 July 11, 1972  MASS TRANSPORTATION SYSTEM  Inventors: Peter F. Glrard, La Mesa; John M. Peterson, San Diego, both of Calif.
3,477,387 ll/l969 Bing 104/23 FS 3,155,050 ll/l964 Hafner l04/l38 R 3,52l,$66 7/l970 Van Veldhuizen... l04/23 FS 3,583,323 6/1971 Paris 104/23 FS Primary Examiner-Arthur L. La Point Assistant ExaminerD. W. Keen Attorney-Carl R. Brown, Stephen L. King and Kenneth W. Mateer ABSTRACT A high speed mass transportation system. in which a train unit rides in an arcuately concave, narrow guideway and is aerodynamically supported on airfoils conforming to the arcuate fonn of the guideway. The center mass of the vehicle is below the center of radius of the guideway, which provides a self-stabilizing and automatic banking action in high speed turns, so that passengers are not subjected to lateral accelerations. The airfoils are spaced several inches above the guideway at cruising speed, so that the surface finish of the guideway is not unduly critical and cost is minimized. Retractable wheels are provided for supporting the train unit at low speeds and on flat surfaces. Propulsion may be by means of direct thrust, such as a propeller, or by electrical drive means, such as a linear induction motor.
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INVENTORS PETER F. GIRARD JOHN M. PETERSON az-aam ATTOR NEY PATENTEDJuL 1 1 m2 SHEET 7 BF 7 INVENTORS PETER F. GIRARD JOHN M. PETERSON ATTORNEY MASS TRANSPORTATION SYSTEM BACKGROUND OF THE INVENTION In the field of mass transportation, many different proposals have been made for increasing vehicle speed. Studies have determined that a cruise speed of about 300 mph is practical for various stage lengths, with reasonable acceleration and deceleration. At such speed, wheels become impractical due to the loads and wear imposed by very high rotational speed. A number of tracked air cushion vehicles have been proposed or developed, in which a vehicle is supported on a special track by pressurized air, to provide a low friction bearing. Since air leakage must be minimized to maintain the air cushion, clearances between the track and the vehicle are small and the track must be precisely made, at high cost. This is particularly true with high pressure air pad support, in which clearance is a few thousandths of an inch. In addition to direct support of the vehicle, cushioning or other support must be provided for handling side loads and for stabilization in turns. In any such arrangement, the air cushion requires a power source of considerable size, which must be carried on the vehicle.
SUMMARY OF THE INVENTION In the system described herein, the generated air cushion and its attendant power source are eliminated, resulting in a lighter and less complex vehicle. The guideway is a trough-like track of arcuately concave cross section, and is readily constructed from concrete with simple forms. The train unit, or vehicle, comprises an elongated body supported on longitudinally spaced airfoils, which extend transversely and conform to the arcuate shape of the guideway. At high speed, the airfoils ride, in ground efl'ect, several inches above the guideway surface and provide lifting support for the vehicle. The center of mass of the vehicle is well below the center of radius of the guideway cross section, which gives the vehicle an automatic rolling and self-stabilizing capability in banked turns, thus avoiding subjecting the passengers to lateral accelerations The ail-foils are supported below the vehicle body on legs which provide roll stabilization, and also contain retractable wheels which are lowered to support the vehicle at low speeds and when stopped. Certain of the wheels are steerable for maneuvering the vehicle on a flat surface. By spacing the airfoils below the body, the transverse span of the airfoils can be reduced, minimizing the required width of guideway. Some or all of the alrfoils are provided with automatic flaps which vary the lift in accordance with pressure fluctuations and thus aid in damping longitudinal oscillations. Propulsion may be by propeller means at the rear of the vehicle, or by electrical means such as a linear induction motor.
The primary object of this invention, therefore, is to provide a new and improved mass transportation system.
Another object of this invention is to provide a new and imroved system in which a vehicle rides in a concave guideway and is aerodynamically supported on airfoils conforming to the guideway in such a manner, that the vehicle is self-stabilizing in turns.
Another object of this invention is to provide a new and improved system in which the vehicle has retractable wheels for support at low speeds, and for handling and maneuvering out of the guideway.
A further object of this invention is to provide a new and improved vehicle which is adaptable to different means for high speed propulsion.
Other objects and many advantages of this invention will become more apparent upon a reading of the following detailed description and an examination of the drawings, wherein like reference numerals designate like parts throughout.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a propeller driven vehicle in a section ofguideway.
FIG. 2 is a perspective view of linear induction motor powered vehicles in a covered dual guideway.
FIG. 3 is a top plan view of the propeller driven vehicle.
FIG. 4 is a side elevation view thereof, with the guideway shown in section.
FIG. 5 is a side elevation view of the linear induction motor powered vehicle.
FIG. 6 is a front elevation view, as taken from the right hand end of FIG. 5.
FIG. 7 is an enlarged sectional view taken on line 7-7 of FIG. 5.
FIG. 8 is an enlarged front elevation view showing the cruising position of the vehicle relative to the guideway.
FIG. 9 is a front elevation view showing the wheels extended.
FIG. 10 is a diagrammatic showing of the roll stabilizing action.
FIG. 11 is a diagrammatic showing of displacement as caused by excess speed in a turn.
FIG. 12 is a diagrammatic showing of the stable turning position of the vehicle.
FIG. 13 is an enlarged sectional view taken on line 13-13 of FIG. 6, showing automatic flap structure.
FIG. 14 is a similar sectional view showing the flap lowered.
FIG. 15 is a diagram of the roll control rudders.
FIG. 16 is a side elevation view of a modified vehicle using only two airfoils.
FIG. 17 is a top plan view of the arrangement of FIG. 16.
FIG. 18 is a front elevation view as taken from the right hand end of FIG. 16.
FIG. 19 is a diagram of the banking action of the modified form of the vehicle.
FIG. 20 is a transverse sectional view of a dual guideway.
FIG. 21 is a front elevation view of a leg with shock absorbing means.
FIG. 22 is a sectional view taken on line 22-22 of FIG. 21.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Three forms of the train unit or vehicle are shown, a propeller driven type III, shown in FIGS. 1, 3 and 4 and a linear induction motor driven type 100, shown in FIGS. 2, 5 and 6, both having multiple airfoils spaced along the vehicle. Of these two, the propeller driven type will be described in detail, the only difference being in the means of propulsion and all other Figures of the drawings being applicable to both types. The third type 140, shown in FIGS. 16-19, uses only two airfoils at the front and rear and can be operated in a very narrow guideway where space is limited.
The vehicle I0 rides in a guideway 12 with a concave channel or trough 14 of arcuate cross section, and having flangelike bafiles 16 extending from opposite sides. At high speed the air flow disturbance caused by the vehicle is considerable and the bafiles prevent debris from being sucked into the guideway. The guideway is best made by conventional techniques with suitably reinforced concrete poured in simple fonns. A smooth finish layer may be added on the arcuate face, as at 18 in FIG. 8, but may not be essential. In a complete system the guideway would extend unbroken between selected destinations and, at certain terminals, would open to flat areas for vehicle servicing and related operations. In undulating terrain the guideway could be supported on pillars or other structure where necessary.
Since the vehicle operates in the performance range of a transport aircraft, construction may follow accepted aircraft practises, particularly for minimizing weight, no specific structural details being shown. The vehicle 10 comprises an elongated generally cylindrical body 20, with a suitably streamlined nose 22 and tail section 24. In the tail section is a propulsion unit, shown as a gas turbine engine 26 driving counterrotating pusher propellers 28 through a gearbox 30. An air intake 32 on top of the body supplies air to the engine and the exhaust outlet 34 is directly downwardly. Flow directing means of well known type could be used to direct the exhaust rearwardly to augment the propeller thrust. In the nose section is a control cabin 36, the main cabin 38 having suitable seats 40 and the body being provided with windows 42 and doors 44, as necessary.
Spaced beneath the body are longitudinally spaced airfoils 46, each secured to the body by a pair of downwardly divergent legs 48. Each airfoil is a small wing with suitably eambered surfaces for efficient aerodynamic lift and having pronounced arcuate dihedral conforming to the cross section of the guideway trough 14. Each airfoil is mounted at a predetermined angle of incidence for effective lift, depending on the airfoil section used, and the required performance range. Six airfoils are shown, but any suitable number may be used, the rearmost airfoil having extended legs 50 to suit the tapered tail section 24. By spacing the airfoils below the body, rather than making them side extensions from the body, the transverse span can be reduced since the area beneath the body is clear of aerodynamic interference and can be effectively used. This allows the width of the guideway to be minimized, resulting in low structural and right of way costs. Each airfoil has downwardly projecting tip plates 52, which have an aerodynamic purpose in controlling spanwise flow, and also serve as skids to protect the airfoil from contact with the guideway. Each leg is of streamlined cross section and has a rearwardly extended lower portion 54, on which is a hinged rudder 56 controlled by a suitable actuator 58, as in FIG. 7.
In each leg is a wheel 60 mounted on a bracket 62, which is on the outer end of an arm 64, pivotally attached to the airfoil structure inboard of the leg. As shown in FIG. 9, the wheels extend, swinging about the inboard hinges 66 of arms 64, extension and retraction being controlled by telescopic actuators 68 connected between the upper portion of each bracket 62 and fixed structure in the respective leg. In the extended position the wheels support the vehicle with the airfoils clear of a flat surface 70. To facilitate maneuvering the vehicle at terminal areas, the front and rear wheels are mounted on steerable brackets 72, as in FIG. 7, and are turned by actuators 74 coupled to any conventional steering system adaptable to the vehicle. The other wheels are preferably similarly mounted for steering and are free castering within a limited range to avoid tire scrubbing. For convenience of handling, some or all of the wheels may be provided with individual hub mounted drive motors, indicated at 76 in FIG. 9. Electrical and fluid powered hub drive motors for such a purpose are well known. In the retracted position the wheels project slightly below the airfoils, preferably beyond the tip plates 52 to avoid any contact of the airfoil structure with the guideway in normal operation.
The lift of a wing operating in ground effect is essentially inversely proportional to the distance of the wing above the surface. Thus if a wing sinks toward the surface, the under surface pressure and the effective lift increase, tending to lift the wing to its normal stable position for the particular speed. This has a natural damping effect on vertical oscillation and results in a smooth ride. Damping may be augmented by means of automatic flaps, such as shown in FIGS. 13 and 14. Some or all of the airfoils can be fitted with flaps on portions of their trailing edges. In the under side of the flapped airfoil is a cavity 78, in which is a vertically movable diaphragm 80, biased to a neutral position by a spring 82. A flap 84 is attached to the trailing edge portion 86 of the airfoil by a hinge 88, to swing downwardly through a small range. The flap 84 is connected to diaphragm 80 through a connecting rod 90 and bellcrank 92 so that, when the diaphragm is forced upwardly by an increase in pressure below the airfoil, the flap is correspondingly pulled down, as in FIG. 14. The lowered flap causes a considerable increase in lift for a slight variation in the height H of the airfoil above guideway surface 14, providing a very efi'ective damping action.
The rudders 56 are primarily for roll control, but can also be used for aerodynamic braking if required. A simple diagram of a typical control system is shown in FIG. 15, in which a roll sensor 94, such as a gyroscope, is coupled through a control valve 96 to actuators 58, to move both rudders in the same direction in response to a roll deviation of the vehicle. The arrangement is comparable to a simple one axis autopilot and various systems are well known. For braking efiect, a control unit 98 is coupled to actuators 58 to move the rudders in opposite directions.
The vehicle 100 is similar in all respects except for the propulsion means. The linear induction motor 102, the principles of which are well known, comprises an armature 104 riding along a stator rail 106. In FIGS. 5 and 6, the armature is shown as a streamlined saddle element straddling the rail 106, which is above the vehicle and supported by spaced stanchions 108. To allow for deviations in height and rolling or banking actions of the vehicle, the armature 104 is attached to a fin structure on the vehicle by an arm 112. The arm 112 has double universal joints 114 and a roll axis bearing 116 at the forward end to accommodate the various motions. Since the armature and stator rail can be made to close tolerances by conventional techniques, the armature may be supported by a pressurized air cushion, not shown, to reduce friction. Power may be obtained from a power source in the vehicle. or from conductors along the rail.
A development of the system is shown in FIG. 2, in which dual guideways 14 are used to carry vehicles in opposite directions and are covered by a roof 1 18. The arrangement is adaptable to the vehicles 100 shown, or to the propeller driven type. Roof 118 is supported by truss members 120, which include portions to hold the stator rails 106.
The width of the guideway 14 is not excessive but, where space is critical, the configuration shown in FIGS. 16-19 may be used. In this form the vehicle is lowered as much as possible and the airfoil span reduced to minimize the necessary guideway cross section. The vehicle has a streamlined body 142 with an underside 144 which is arcuate in cross section to conform to the guideway trough 146.'Under the extreme forward portion of the body is a forward airfoil 148 supported on short legs 150 and at the rear is an aft airfoil 152 supported on legs 154. Both airfoils have arcuate dihedral conforming to the trough 146 and are provided with end plates 156. The airfoils are mounted at suitable angles of incidence and positioned so that the body 142 also assumes a small angle of positive incidence in cruising position, as shown in FIG. 16. The body is as low as possible in the guideway and rides in ground effect, so contributing to the aerodynamic lift.
Propulsion is by means of a linear induction motor 158 connected to the body by an articulated arm 160 and riding on a stator rail 162. The legs 150 and I54 may be provided with rudders and the airfoils may have flaps, as described for vehicle l0. Retractable wheels may be mounted in the airfoils and legs, or could be in the body in this configuration.
By lowering the body as much as possible, the radius R of the trough can be minimized, while still keeping the vehicle center of mass 164 well below the center of radius 166. The automatic banking and stabilizing action, indicated in FIG. 19, is thus as described above, the desirable performance characteristics being common to each vehicle.
Where dual guideways are necessary to carry a heavy traffic load, and space is critical, the arrangement shown in FIG. 20 may be used. The structure includes a lower guideway 168 and a coextensive upper guideway 170, which is spaced directly above the lower guideway on posts 172. A roof 174 is supported above the upper guideway on posts 176. The arrangement is adaptable to any of the vehicle types described and provides for double the traffic flow within the ground space of a single guideway.
For maximum ride comfort it may be desirable to control the dynamic motion of the vehicle by some type of shock absorbing means, particularly at low speeds when the vehicle is riding on its wheels. In FIGS. 21 and 22, a typical airfoil supporting leg 178 has a telescopic lower portion 180 to which an airfoil 46 is attached. Cushioning is provided by shock absorbers 182, secured between suitable structural members 184 in upper leg 178 and a structural member 186 in the lower portion 180. The shock absorbers may be spring or other resilient types, or fluid types which would allow ride adjustment. The wheel mounting, similar to that shown in FIGS. 7 and 9 and correspondingly numbered, is adaptable to the telescopic leg by attaching the upper end of the actuator 68 to a racket 188 on the structural member 186.
In a typical operation, starting from a flat surfaces terminal, the vehicle is moved on its wheels to the guideway, where the wheels are almost entirely retracted to lower the airfoils to the guideway surface. With the main propulsion unit in operation, the vehicle is accelerated until the airfoils develop sufficient aerodynamic lift to raise the wheels from the surface, when retraction can be completed. if the wheels project sufficiently in the fully retracted position, the intermediate position of retraction may not be necessary. As speed increases the vehicle will rise to its normal operating height in stable cruising configuration. it should be noted that the vehicle will seek a stable level under a wide range of loading conditions. When heavily loaded the vehicle will ride lower, but the aerodynamic lift increases as the airfoil to surface gap decreases, so the action is self-balancing.
If the vehicle is subjected to a rolling condition, by wind or any oflrer disturbance, indicated by the roll direction arrow 122 in FIG. 10, the rudders 56 are deflected in the opposite direction to counter the roll aerodynamically. The legs themselves provide a degree of roll damping. In a simple rolling condition, or in stable flight, the lift is equal along the full span of each airfoil as indicated by the equal length directional arrows 124.
The arcuate form of the guideway 14 is ideal for making turns at high speed. Since the center of mass 126 of the vehicle is well below the center of radius 128 of the guideway, the vehicle will tend to climb the extended outer wall 130 of a turn structure with a banking action. In the ideal condition, shown in FIG. 12, the acceleration load will be downwardly in the direction of a line 132 through the center of radius 128 and the center of mass 126, with no lateral accelerations affecting the passengers. The lift is constant along the airfoil, as indicated by arrows 134, and is effectively directed toward the center of radius.
In the event that the vehicle is subjected to a lateral load, as by excessive speed in a turn, the outboard portion of the airfoil, as related to the direction of turn, will be forced closer to the guideway surface. However, as shown in FIG. 11, the resultant lift will be higher at the outboard portion of the airfoil, indicated by graduated directional arrows 136 to 138, due to the non-constant airfoil to surface separation. As a result, the vehicle will be aerodynamically returned to the stable turn condition of FIG. 12, with a self-stabilizing action.
The automatic banking and stabilizing action, without the need for special guidance structure, ensures a smooth ride and greatly simplifies guideway construction.
When approaching a destination, the vehicle is decelerated until the load is transferred to the wheels. The wheel hub motors 76 could be readily adapted to spin up the wheels prior to contact with the guideway, to reduce tire wear. lfthe vehicle is to leave the guideway for lading and unloading, the wheels are extending to raise the airfoils to clearance height.
It will be evident that the use of aerodynamic support in ground effect, makes it possible to use a simple light weight vehicle, requiring considerably less accessory and support equipment than a comparable air cushion type vehicle.
Having described our invention, we now claim:
1. In a mass transportation system,
an elongated guideway having a concave trough of arcuate cross section,
a vehicle, comprising an elongated body, with a plurality of longitudinally spaced, vehicle supporting, aerodynamic lifting airfoils mounted below the body substantially clear of aerodynamic interference therewith, said airfoils extending transversely to the length of the body and having arcuate dihedral conforming to the cross section of said guideway, to operate in ground effect with the guideway surface,
the radius of curvature of said guideway cross section being such that the effective center of mass of the vehicle is below the center of radius, when the vehicle is riding in the guideway,
and propulsion means mounted on said vehicle.
2. A mass transponation system according to claim 1, wherein said body has a pair of legs fixed to and supporting each of said airfoils, said legs being of streamlined cross section, at least some of said legs each having a rearwardly extended lower portion, with a rudder pivotally mounted thereon, and control means connected to said rudders for selective operation thereof.
3. A mass transportation system according to claim 2, wherein at least some of said legs each has a rearwardly extended lower portion, with a rudder pivotally mounted thereon, and control means connected to said rudders for selective operation thereof.
4. A mass transportation system according to claim 2, wherein said control means includes roll sensing means in said vehicle, and actuating means controlled by said roll sensing means to move said rudders in a direction to oppose the sensed roll.
5. A mass transportation system according to claim 4, wherein said control means further includes means for moving the rudders on each pair of legs in opposite directions.
6. A mass transportation system according to claim 2, and including wheels retractably mounted in at least some of said pairs of legs, said wheels extending below said airfoils.
7. A mass transportation system according to claim 6, and including actuating means for extending said wheels sufficiently to raise said airfoils clear of a flat supporting surface.
8. A mass transportation system according to claim 6, wherein said airfoils have downwardly projecting tip plates thereon, said wheels being movable between a retracted position projecting below said airfoils slightly further than said tip plates, and an extended position in which the airfoils are sup ported clear of a flat surface.
9. A mas transportation system according to claim 1, wherein certain of said airfoils each has a flap pivotally mounted on a trailing edge portion thereof to swing downwardly through a limited range, and control means, sensitive to changes in pressure below the respective airfoil, connected to each flap.
10. A mass transportation system according to claim 9, wherein said control means comprises a cavity in the underside of the airfoil, a pressure sensitive diaphragm mounted in said cavity and linkage means connected from said diaphragm to the associated flap to lower the flap when pressure below the airfoil increases.
11. A mass transportation system according to claim 1, wherein said airfoils are spaced substantially equally along the length of said body.
12. A mass transportation system according to claim 1, wherein said airfoils include a forward airfoil below the extreme front portion of said body, and an aft airfoil below the extreme rear portion of the body.
13. A mass transportation system according to claim 12, wherein said body has an underside portion of substantially arcuate convex cross section conforming to said guideway, said airfoils being positioned to hold the body at a positive angle of incidence relative to the guideway surface and in ground effect proximity thereto.
14. A mass transportation system according to claim I, wherein said guideway has slipstream deflecting baffles extending outwardly from opposite sides and coextensive therewith.