Abstract:
A vertical wind tunnel flight simulator comprises a flight chamber wherein a flier may experience a freefall simulation. Airflow to support the flier is induced by fans connected above the flight chamber through a duct. A staging area having openings to the flight chamber is adjacent to the flight chamber. One or two return air ducts are used to return air from the fans outlet to the fans inlet. Opposed louvers are included on at least one duct segment thereby regulating the temperature via forcing ambient air into the simulator. The use of many duct segments having diverging walls adds commercial value to the system by lowering the height. Mounting components on the roof and behind walls creates a spectacular pedestrian viewing scene of people in flight.

Description:
CROSS REFERENCE PATENTS  
       [0001]     U.S. Pat. No. 6,083,110 is incorporated herein by reference.  
       FIELD OF THE INVENTION  
       [0002]     The present invention relates to the field of vertical wind tunnels, more particularly, to temperature controlled return flow vertical wind tunnels used as skydiving simulators and amusement devices.  
       BACKGROUND OF THE INVENTION  
       [0003]     Wind tunnels are well known in the art. Wind tunnels are available in many types and styles depending upon the needs of the user. These include subsonic wind tunnels with and without return flow, transonic wind tunnels with and without return flow, vertical subsonic wind tunnels with and without return flow, supersonic and hypersonic wind tunnels with and without return flow, and compressible flow wind tunnels.  
         [0004]     The majority of the wind tunnels are used for research and testing purposes. These include testing of conventional aircraft, helicopters, parachutes and other aerodynamic devices, wing surfaces, control surfaces, submarines, rockets and other launch vehicles, ground vehicles, buildings and other basic flow investigations.  
         [0005]     Horizontal wind tunnels (those in which the air in the full speed section of the tunnel flow generally horizontally) are used for aerodynamic research and testing and are generally owned by major defense oriented corporations, the Federal government, or educational institutions and universities. Some of these have been converted or adapted for vertical operation (in which the air in the full speed section of the tunnel flows generally vertically) but most or all perform poorly in that role. Design constraints that apply to vertical wind tunnels used for freefall simulation differ from those of horizontal testing tunnels. In a vertical wind tunnel/freefall simulator, it is important that the objects in the full speed section of the wind tunnel (in this case the human beings in flight) be able to move about inside that section to experience or practice human body flight. In a horizontal test tunnel, the objects placed in the tunnel are usually static objects observed or measured by others. For this reason, this fastest part of a horizontal wind tunnel is called a “test section”. In a vertical wind tunnel, this same area is instead referred to as the “flight chamber”.  
         [0006]     In a vertical wind tunnel, it is important that people flying inside the tunnel be allowed to rotate in and out of the flight chamber without stopping the airflow. In contrast, there is little need to move the static objects in the test section of a horizontal wind tunnel during its operation. Furthermore, since fliers in a vertical wind tunnel are free to move about inside flight chamber, it is necessary to constrain their movement to appropriate parts of the system. While it is possible to put a safety net on both the upstream and downstream ends of the flight chamber, these produce an enormous amount of drag which creates noise and increases the power required to attain any given speed. In fact, such a pair of nets can consume as much as 30% to 50% of the total power required to operate such a wind tunnel. It is also important to prevent occupants from flying laterally outside of the air column and falling unsupported to the floor below. For this reason, the most advanced vertical wind tunnels are designed such that the air column extends completely from one wall of the flight chamber to the other. This is not necessary in horizontal wind tunnels.  
         [0007]     Vertical wind tunnels used for freefall simulation often have to operate in noise sensitive environments such as amusement parks and shopping malls. Horizontal testing tunnels can be located away from the crowds where they are free to make as much noise as is necessary.  
         [0008]     As amusement devices, freefall simulators must compete with other amusements on the basis of price and can often be operated on a near continual basis. These two factors make energy efficiency critical to successful commercial operation of a freefall simulator. Energy efficiency is much less important for horizontal testing tunnels in which one often takes hours or days to set up an experiment and then only runs the tunnel for a few minutes to collect the necessary data.  
         [0009]     Height is a major constraint of freefall simulators which stand upright and often must be sited in high-density entertainment venues that have severe height limitations. This is not true of horizontal testing tunnels which sit on their side and can be successfully located far away from any crowds.  
         [0010]     Finally no known prior art has focused on designing these systems to optimize visibility to public spectators in a shopping mall or other high density entertainment venue.  
         [0011]     To make a commercially viable vertical wind tunnel for skydiving simulation, one must (1) move enough air and do so smoothly enough to adequately simulate freefall for one or more persons in the flight chamber; (2) with a device that is short enough and quiet enough to be located where large numbers of potential customers tend to be; and, (3) at power consumption levels low enough to make the price of the experience acceptable to the public.  
         [0012]     The inventive challenge of satisfying these competing requirements is met by the present invention. High airspeeds are required at the flight chamber to float one or more human beings. However, moving air through ductwork at high speeds creates an enormous amount of sound and heat and requires a huge amount of power. Consequently, most modern wind tunnels expand and slow the air just downstream of the flight chamber to decrease power consumption, noise output and heat generation. Doing so can reduce power consumption by more than 60%, and only by doing so will vertical wind tunnels become commercially viable as entertainment devices or skydiving simulators.  
         [0013]     However, if one expands the airflow in any section of a wind tunnel too rapidly, the flow will “separate” and become turbulent rather than laminar. This will make the entire system perform poorly, increasing power consumption and decreasing flow quality to the point that the device will not adequately simulate true freefall. The threshold at which this flow separation occurs in an expanding duct is fairly well defined in the literature; in simple terms, the walls of such an expansion cone cannot diverge away from one another at greater than 9-12 degrees. For that reason, increasing the length of horizontal test tunnels or the height of vertical wind tunnels tends to improve efficiency. Unfortunately, while this is easily done for a horizontal system, doing so in a vertical system dramatically increases the construction and operation cost and reduces the number of places at which one can gain governmental approval to build. Consequently, minimizing height while maximizing the expansion and deceleration of the airflow downstream of the flight chamber is the key to making a vertical wind tunnel commercially successful. Similarly, constraining the occupants to the safe areas of the wind tunnel without increasing drag and power consumption is essential.  
         [0014]     The prior art wind tunnels do not offer a design that is quiet and short enough to be built in high density shopping and entertainment venues while remaining efficient enough to allow commercially viable operation.  
         [0015]     What is needed is a vertical wind tunnel amusement and training device having a flight chamber on the inlet side of the fans for improved airflow, speed and quality, at lower power consumption and higher safety for the fliers.  
         [0016]     What is needed is a vertical wind tunnel amusement and training device having a sealed and pressure balanced staging area adjacent and connected to the flight chamber in a way that allows people to move in between the two without stopping the airflow.  
         [0017]     What is needed is a vertical wind tunnel amusement and training device having transparent windows allowing spectators, instructors or others outside the flight chamber to see into it.  
         [0018]     What is needed is a vertical wind tunnel amusement and training device having a plurality of smaller fans rather than a single, more expensive and difficult to maintain fan.  
         [0019]     What is needed is a vertical wind tunnel amusement and training device having one or more return air ducts to conserve heat, reduce energy consumption, reduce noise and allow all-weather operation.  
         [0020]     What is needed is a vertical wind tunnel amusement and training device having only one or two return ducts even though it may have a greater number of fans than return ducts.  
         [0021]     What is needed is a vertical wind tunnel amusement and training device having fans housed in low profile casings that allow them to be mounted as closely together as possible so that more than one fan can be connected to each return air duct without the need for long transition ducts that would increase the height or width of the entire system.  
         [0022]     What is needed is a vertical wind tunnel amusement and training device having a passive air exchange system that ejects heated air and draws in cooler ambient air in order to most efficiently control the temperature inside the wind tunnel.  
         [0023]     What is needed is a vertical wind tunnel amusement and training device having a passive air exchange system the components of which form a “nozzle” or flow contaction that not only mechanically ejects the air from inside the wind tunnel but also creates the proper pressure gradient between the inside and outside of the wind tunnel and thereby encourages the efficient exchange of air between the wind tunnel and the ambient air.  
         [0024]     What is needed is a vertical wind tunnel amusement and training device having a mesh “floor” made of specially designed cables that produce less drag and, therefore, less noise than conventional cables.  
         [0025]     What is needed is a vertical wind tunnel amusement and training device having at least one zero-drag electronic upper barrier instead of a physical net to prevent fliers from moving too high in the flight chamber and quickly modulating the speed of the air to bring them back down to and hold them at a safe level.  
         [0026]     What is needed is a vertical wind tunnel amusement and training device having the lowest possible total height for any given efficiency in order to reduce construction costs and meet common governmental constraints on building height.  
         [0027]     What is needed is a vertical wind tunnel amusement and training device optimized for height by having most or all of the components downstream of the flight chamber expand the air as rapidly as possible without creating flow separation.  
         [0028]     What is needed is a vertical wind tunnel amusement and training device optimized for height by providing an optional flight chamber in which the air is expanded as much as possible without creating separation as it passes through the flight chamber section or a flight chamber that is actually shaped like a diffuser.  
         [0029]     What is needed is a vertical wind tunnel amusement and training device optimized for height and overall size by mounting the fans in conical ducts that themselves act as “diffusers”.  
         [0030]     What is needed is a vertical wind tunnel amusement and training device that allows installation configurations which optimize spectator viewing areas of the fliers to pedestrians in a shopping mall.  
         [0031]     The present invention meets these needs.  
       SUMMARY OF THE INVENTION  
       [0032]     An aspect of the present invention is to provide a vertical wind tunnel amusement device having a flight chamber situated on the inlet side of a plurality of fans which are in turn connected to a plurality of expanding return air ducts, thereby maximizing efficiency while minimizing the height of the amusement device.  
         [0033]     Another aspect of the present invention is to provide a vertical wind tunnel having a flight chamber on the inlet side of the fans for improved airflow speed and quality, at lower power consumption and higher safety for the fliers.  
         [0034]     Another aspect of the present invention is to provide a vertical wind tunnel having a two-stage staging area adjacent and connected to the flight chamber in a way that allows people to move in between the two without stopping the airflow.  
         [0035]     Another aspect of the present invention is to provide a vertical wind tunnel having transparent windows allowing spectators, instructors or others outside the flight chamber to see into it, including in a shopping mall venue.  
         [0036]     Another aspect of the present invention is to provide a vertical wind tunnel having a plurality of smaller fans angled in a non-parallel alignment rather than a single, more expensive and difficult to maintain fan.  
         [0037]     Another aspect of the present invention is to provide a vertical wind tunnel having one or more return air ducts to conserve heat, reduce energy consumption, reduce noise and allow all-weather operation.  
         [0038]     Another aspect of the present invention is to provide a vertical wind tunnel having only one or two return ducts even though it may have a greater number of fans than return ducts.  
         [0039]     Another aspect of the present invention is to provide a vertical wind tunnel having fans housed in low profile, diffusing casings that allow them to be mounted as closely together as possible so that more than one fan can be connected to each return air duct without the need for long transition ducts that would increase the height or width of the entire system.  
         [0040]     Another aspect of the present invention is to provide a vertical wind tunnel having a passive air exchange system with adjustable inlet/outlet doors that mechanically ejects heated air from the system and draw in cooler ambient air in order to most efficiently control the temperature inside the wind tunnel with minimal extra work by the fans.  
         [0041]     Another aspect of the present invention is to provide a vertical wind tunnel in which the adjustable inlet/outlet doors are arranged such that they also form a “nozzle” or flow contraction thereby creating a favorable pressure gradient between the inside and outside of the tunnel and encouraging the air exchange in order to efficiently control the temperature inside the wind tunnel with minimal extra work by the fans and without the use of other more costly air cooling technologies.  
         [0042]     Another aspect of the present invention is to provide a vertical wind tunnel in which the position of the inlet/outlet doors is controlled by known means in order to maintain a comfortable temperature inside the wind tunnel.  
         [0043]     Another aspect of the present invention is to provide a vertical wind tunnel having a mesh “floor” made of specially designed cables (preferably steel) that produce less drag and, therefore, less noise than conventional cables.  
         [0044]     Another aspect of the present invention is to provide a vertical wind tunnel having one or more zero-drag electronic upper barriers instead of a physical net designed to prevent fliers from moving too high in the flight chamber and capable of quickly modulating the speed of the air to bring fliers back down to and hold them at a safe level.  
         [0045]     Another aspect of the present invention is to provide a vertical wind tunnel having the lowest possible total height for any given efficiency in order to reduce construction costs and meet common governmental constraints on building height.  
         [0046]     Another aspect of the present invention is to provide a vertical wind tunnel optimized for height by having not just the primary diffuser just downstream of the flight chamber but also most or all of the components downstream of the flight chamber expand the air as rapidly as possible without creating flow separation.  
         [0047]     Another aspect of the present invention is to provide a vertical wind tunnel optimized for height by expanding the air as much as possible without creating separation as it passes through the flight chamber. This diffusing flight chamber could also be thought of as a zero-height flight chamber or zero-length test section.  
         [0048]     Another aspect of the present invention is to provide a vertical wind tunnel optimized for height by mounting the fans in conical ducts that themselves act as “diffusers”.  
         [0049]     Another aspect of the present invention is to provide a zero height flight chamber wherein the fliers fly in an expanding diffuser chamber with a reduced air velocity the higher they fly, thereby forming a self-catching flow in the chamber to slow the flier as he or she descends.  
         [0050]     Other aspects of this invention will appear from the following description and appended claims, reference being made to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.  
         [0051]     To eliminate the risk of occupants falling out of the air column and injuring themselves, the air column extends completely from one wall of the flight chamber to the other. This “wall to wall” airflow also reduces drag at the edges of the air column and increases efficiency of the entire system. The airflow passes through a “cable floor” into the flight chamber. The cable floor provides support for the users when the airflow through the flight chamber is not sufficient to support them. At or near the upper (or downstream) end of the flight chamber, a “virtual net” comprised of one or more electronic (preferably optic) sensors, monitors the position of the occupant(s) within the flight chamber. In the preferred embodiment, the control system will automatically lower the speed if the occupant(s) fly too high in the flight chamber.  
         [0052]     The flight chamber can be round, oval or polygonal and can range from a bit less than 75 square feet to over 160 square feet in area. The flight chamber may accommodate up to six users at a time. The airflow velocity in the flight chamber can reach as high as 160+ mph, which-will fully support as many as six users. In the preferred embodiment, one or more of the walls of the flight chamber include or comprise flat or curved windows constructed of transparent Plexiglas®, acrylic plastic, glass or similar high strength transparent material. When present, the windows into the flight chamber allow an unrestricted view of the activities taking place within the therein.  
         [0053]     Adjacent to the flight chamber is a staging area. The flight chamber has an entry opening and exit opening to the staging area through which a user or multiple users may enter and exit the flight chamber. In certain embodiments in which rotations of occupants in and out of the flight chamber might be less frequent, these opening may be fitted with doors which slide, roll or otherwise move to close one or both of these openings. Users wait in the staging area for their turn in the flight chamber. The staging area has transparent windows so that an observer may view the flight of any person(s) within the flight chamber without entering the staging area. The staging area has a single or multiple doors that open periodically to allow people to exit the entire system. The staging area may also be fit with an optional “piggyback” or secondary staging area. This creates an airlock that allows groups to rotate in and out of the staging area from outside the system without requiring the airflow to stop.  
         [0054]     The area above (downstream of) each doorway in upper section of the flight chamber may include perforated panel which provides an alternate airflow path when users are entering and exiting the flight chamber. In the preferred embodiment, a small flow deflector will also be located below (upstream of) the cable floor just below each opening between the flight chamber and staging area to minimize the amount of air moving between them and reduce the amount of balancing necessary.  
         [0055]     The fans and other controls can be operated from inside the staging area, inside the flight chamber or from an attached or remote control room. The fans are controlled to achieve the optimum airflow velocity through the flight chamber.  
         [0056]     Next above the perforated section is the primary divergent diffuser. The primary diffuser diverges at approximately 3.5 to 5 degrees from the major axis providing a “equivalent cone angle” of 7 to 10 degrees. The increasing cross-sectional area reduces the velocity of the airflow from the flight chamber to the fans. Above (or downstream of) the primary diffuser is the upper plenum which may include the first set of high efficiency turning vanes. In a single return system these turning vanes (or simply the plenum if no vanes are used) redirect the airflow from substantially vertical to substantially horizontal. In a multiple return system, these vanes (or simply the plenum if no vanes are used) split the air into to basically equal flows and turn each flow from substantially vertical to substantially horizontal.  
         [0057]     The airflow then passes through the inlet ducts and into the fans. The fan inlet duct transitions the flow from roughly square or rectangular to roughly round. In the preferred embodiment, the fan inlet ducts act as diffusers expanding the flow area as much as possible without creating flow separation. The fans are preferably high-efficiency axial flow fans, although any fan adapted for use in a wind tunnel is acceptable. In the preferred embodiment, the fans contain a bullet-shaped nosecone and a teardrop-shaped tailcone. In the preferred embodiment, the fan casings act as diffusers and are sized such that, after taking into account the area in the center of the fan obscured by the nosecone, fan centerbody and tailcone, the net flow area through the fans increases as much as possible without creating flow separation. The velocity of the airflow through the invention is controlled by either changing the pitch of the fans or by changing the rotational speed of the fans.  
         [0058]     The airflow passes through the fans and into the exit ducts which also transition from roughly round to roughly square or rectangular. In the preferred embodiment, the exit ducts are act as diffusers expanding the airflow as much as possible without creating flow separation. The airflow travels through a set of exit ducts to the second set of high-efficiency turning vanes (if used) which turn the air from substantially horizontal to substantially vertical.  
         [0059]     The airflow then enters the return air ducts. In the preferred embodiment, these return air ducts are also shaped as divergent diffusers expanding the airflow as much as possible without creating flow separation. In the preferred embodiment, each return air duct has an air exchange mechanism comprised of an even number of louvers located on opposing faces of the return air duct. These are situated and sized so that they together create a nozzle or sudden contraction in the flow area at the point of the louvers. This nozzle [increases] decreases the [dynamic] static pressure at that point of the system and assists in the expulsion of heated air from the wind tunnel through the exhaust louver. This lowers the pressure in the system and assists the inlet louvers as they draw in cooler ambient air from outside of the system. This arrangement allows heated air in the system to be replaced with cooler ambient air, thereby allowing a user to adjust the temperature in the flight chamber for flyer comfort without the need for expensive alternatives such as air conditioning or evaporative cooling.  
         [0060]     At the bottom (or downstream) end of the return air towers, the air again passes through a set of turning vanes (or simply a duct with a 90 degree turn if no vanes are used) that redirects the air from a substantially vertical to a substantially horizontal path. The air then enters the bottom plenum which may also act as a divergent diffuser expanding the air as much as possible without causing flow separation. At the end or the (or downstream) end of the bottom plenum, the air again passes through a set of turning vanes (or simply a duct with a 90 degree turn if no vanes are used) that redirects the air from a substantially horizontal to a substantially vertical path. In a multiple return system, the flows will be re-joined at this point.  
         [0061]     The air then passes into the inlet contractor. This trumpet-shaped or bell-shaped device quickly reduces the flow area and accelerates the air to its maximum speed just ahead of the flight chamber. Here again aerodynamic laws govern how quickly one can reduce this flow area without degrading the quality of that flow. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0062]      FIG. 1  is a top perspective view of a single return simulator.  
         [0063]      FIG. 2  is a cutaway view of the  FIG. 1  embodiment.  
         [0064]      FIG. 3  is a top perspective view of the flight chamber of  FIG. 1 .  
         [0065]      FIG. 4  is a top plan view of an oval outlet, rectangular inlet airflow contractor.  
         [0066]      FIG. 5  is a schematic view of an oval/polygon shaped outlet of an airflow contractor.  
         [0067]      FIG. 6  is a schematic view of an oval outlet airflow contractor.  
         [0068]      FIG. 7  is a schematic view of an oval viewing area.  
         [0069]      FIG. 8  is a top perspective view of a double airlock staging area.  
         [0070]      FIG. 9  is a schematic view of a temperature regulator.  
         [0071]      FIG. 10  is a side, cutaway view of the temperature regulator of  FIG. 9 .  
         [0072]      FIG. 11  is a top perspective view of deflectors on flight chamber entrance doors.  
         [0073]      FIG. 12  is a close up view of a deflector.  
         [0074]      FIG. 13  is a side cutaway view of a fan and housing.  
         [0075]      FIG. 14  is a side cutaway view of two fans and housings mounted divergent from a centerline therebetween.  
         [0076]      FIG. 15  is a top perspective view of a two return simulator.  
         [0077]      FIG. 16  is a cutaway view of the  FIG. 15  embodiment.  
         [0078]      FIG. 17  is a schematic view of a V footprint two return simulator.  
         [0079]      FIG. 18  is a schematic view of a V footprint two return simulator in a mall.  
         [0080]      FIG. 19  is a schematic view of a multi-simulator configuration in a building.  
         [0081]      FIG. 20  is a side perspective view of a mall type viewing area for a simulator.  
         [0082]      FIG. 21  is a schematic view of a dual contractor (one underground and horizontal) system.  
         [0083]      FIG. 21A  is a sectional view taken along lines  21 A- 21 A of  FIG. 21 .  
         [0084]      FIG. 22  is a top perspective view of a cable floor.  
         [0085]      FIG. 23  is a side perspective view of an anti-drag cable, first embodiment.  
         [0086]      FIG. 24  is a view of a second embodiment cable.  
         [0087]      FIG. 25  is view of a third embodiment cable.  
         [0088]      FIG. 26  is a schematic view of a floor sensor/shutoff system.  
         [0089]      FIG. 27  is a top perspective view of a rounded diffuser.  
         [0090]      FIG. 28  is a schematic view of a cruise ship having a water-cooled simulator. 
     
    
       [0091]     Before explaining the disclosed embodiment of the present invention in detail, it is to be understood that the invention is not limited in its application to the details of the particular arrangements shown, since the invention is capable of other embodiments. Also, the terminology used herein is for the purpose of description and not of limitation.  
       DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0092]     Referring first to  FIG. 1 a  single return simulator  1  is shown, wherein height L 1  is preferably in the range of about 50-120 feet. Some installations may bury all components below a ground level of either G 1  or G 2 . The flight chamber  10  may be made entirely or partially with transparent panels. If ground level is at G 2 , then an opaque pedestal-type image formed in area d 1  which may be about seven feet high. This embodiment in a mall creates an eye-catching, live action human flight studio in the flight chamber  10 . This design attracts new “fliers” who pay to experience simulated skydiving in flight chamber  10 . Dotted line R represents a roof, wherein components above R can be roof-mounted to reduce noise. Dotted line W represents a wall, wherein components beyond the wall W away from the flight chamber  10  could be isolated from the flight chamber to reduce noise near the flight chamber  10 .  
         [0093]     Most prior art flight chambers provide for parallel walls in the flight chamber so that experienced fliers can practice maneuvers at a constant wind velocity perhaps at around 140 miles per hour. Simulator  1  has a “zero height” flight chamber along elevation  11 . Elevation  11  is the line which joins the airflow contractor  9  to the airflow diffuser  10 , wherein the diffuser  10  has diverging walls  20 , 21 , 22 , etc., and the diffuser  10  also serves as the flight chamber  10 .  
         [0094]     Nominally the air speed at line  11  is at about 140 mph, the maximum speed in the simulator. As the flier goes higher in the flight chamber  10  to the top of the flight chamber  10  to junction  110 , the air speed drops, perhaps to about 120 mph. Fliers can change their drag profiles from a maximum spread eagle position to a minimum human ball position. Thus, if a flier ascends to the top of the flight chamber  10  and then changes his drag to a human ball shape, he will fall downward. The diffuser shape of the flight chamber  10  will provide a self-braking system due to the increasing airspeed with each incremental descent down into the flight chamber  10 . A safety net is provided a line  11 .  
         [0095]     The diverter  2  meets the diffuser  10  at junction  110 . The air is diverted from a vertical path to a horizontal path in the diverter  2 . All the diverters  2 , 4 , 6 , 8  change the air direction by about 90 degrees.  
         [0096]     The fan assembly  3  accelerates the air, perhaps with two side-by-side fans. The basic dynamics in a return air simulator involve compromises in energy efficiency, noise and size. In the simplest design, one would attempt to keep the airflow close to full speed for the entire loop through the simulator. However, the height would have to rise, the noise would be enormous, and the heat from friction in the plenums would be enormous. Therefore, for more efficient operation, it is necessary to slow the air down during its travel through the simulator loop by enlarging the cross-sectional areas of the plenum to attain commercially acceptable levels of height h 1  as well as noise, and simultaneously attempt to use the least horsepower possible for the fans.  
         [0097]     The diverters  2 , 4 , 6 , 8  generally do not have diverging walls due to cost construction considerations. The fan housing segment  300  and the fan section  3  have diverging walls. The top plenum  30  has diverging walls. The Vertical return plenum  5  has diverging walls. The bottom plenum  7  does not have diverging walls due to tradeoffs in cost construction considerations. Bottom plenum  7  could have diverging walls.  
         [0098]     The airflow contractor  9  has converging walls functioning to narrow the cross-sectional plenum area, thereby accelerating the air to about 140 mph for flight simulation.  
         [0099]     The air inlet  12  brings in ambient air to cool the simulator air.  
         [0100]     Referring next to  FIG. 2 a  schematic representation of the internal workings of the simulator  1  is shown. Airflow is shown by the arrows F. Diverting vanes  200 ,  201 ,  202 ,  203  each change the airflow direction by 90 degrees. Two fans  40 , 41  are schematically shown mounted horizontally side by side in their housing  3 , refer to  FIG. 13  for a perspective view, wherein right after the fans a plenum diffuser  300  expands and slows the airflow. The diffusing continues in top plenum  30 , and then in vertical return plenum  5 , and finally through the flight chamber  10 .  
         [0101]     A passive temperature regulation system is provided by having air inlet  12  louver  120  face downstream. Additionally the air outlet  26  has a louver  260  that faces upstream. By mounting the inlet  12  about opposite outlet  26 , a reducing nozzle is formed by louvers  120 ,  260 , thereby creating a decreased static pressure zone V downstream from the inlet  12 . Therefore, ambient air is [forced passively] drawn into the simulator  1  without the use of an additional fan.  
         [0102]     Referring next to  FIG. 3  the diffuser/flight chamber  10  is in the shape of a polygon (octagon) as seen by the base B. Base B is covered by a safety net. The walls  20 , 21 , 22  etc. diverge at an optimal aerodynamic angle in the range of about 7-12 degrees from each other. The top of the flight chamber  10  is seen as a rectangle at arrow  110 . All or some of the walls  20 , 21 , 22  etc. may be transparent.  
         [0103]     Referring next to  FIG. 4  an airflow contractor  400  has the preferred design of a rectangular inlet  401  and an oval outlet  402 . Transition walls  403  contract the airflow from the inlet  401  to the outlet  402 . Preferably the height h 2 ,  FIG. 2 , which is sometimes buried underground equals length d 4 . This combination of shape and dimensions form a cost-effective balance for a relatively low height, and commercially viable simulator  1 .  
         [0104]     Referring next to FIGS.  5 , 6 , 7  the term “oval outlet” airflow contractor covers any oval-like shape such as polygon oval outlet  500  and perfectly oval outlet  600 . The oval-like shape provides for a larger viewing area  700  compared to a round outlet having the same cross-sectional area. Area  701  includes a staging and entry area. The flight chamber bottom B 1  could be in a mall with expensive retail space, wherein the larger viewing area  700  has considerable commercial value.  
         [0105]     Referring next to  FIG. 8 a  two-stage staging chamber  800  consists of a flight chamber bottom B 2  with a flight chamber wall  809  having windows  810  and flier entrances  806 , 807 . Entrances  806 , 807  can be doorless or with hinged doors or with sliding doors. So long as doors  801 , 805  are closed the fans do not have to be shut down to allow fliers to enter/leave the flight chamber  10 . Ambient pressure is shown as A. Doors  801 , 805  open from ambient A to first staging room  802  and second staging room  804 . Door  803  separates the staging rooms  802 , 804 . In operation a group of fliers could enter room  804  while door  803  is closed, then door  805  is closed. Then the fliers would enter room  802  with doors  801 , 805  closed. Flier entrances  806 , 807  are used.  
         [0106]     Referring next to  FIGS. 9,10  the temperature regulating system  1000  consists of a plenum  5  having an airflow F. The outlet  26  is located opposite the inlet  12 , but slightly upstream at a distance d 11  chosen by design parameters. Preferably louvers  120 , 260  are controllable from a control room to vary the air exchange from ambient A to the plenum  5 . Inlet air volume I must approximate outlet air volume  0 . The decrease in internal static pressure V is formed by contracting and accelerating the air at nozzle N.  
         [0107]     The air exchange system used for closed-circuit wind tunnels disclosed herein consist of two large louvers in each return leg of the tunnels: an exhaust louver and an intake louver. The exhaust and intake louvers are located and oriented so that there is favorable interaction between them. This location is part of what is novel about this system.  
         [0108]     The leading edge of the exhaust louver deflects into the tunnel and scoops out the air from inside the tunnel. The intake louver is located on the opposite tunnel wall from the exhaust louver. Its hinge line is designed to line up with the leading edge of the exhaust louver at the design setting. The trailing edge of the intake louver is deflected into the tunnel. It is deflected to a greater extent than the exhaust louver to cause the internal airflow velocity to increase by creating nozzle N. This is the key. That increase in velocity causes a decrease in the internal static pressure (Bernoulli&#39;s law). The lower internal static pressure (below atmospheric) actually sucks air into the inlet. As a minimum, the intake louver has the same chord or length as the exhaust louver. In some wind tunnel configurations it is desirable that the intake louver have a greater length or chord than the exhaust louver to reduce the deflection required.  
         [0109]     Traditional wind tunnel air exchangers either have the exhaust and intake in separate sections of the wind tunnel, or if they are in the same part of the wind tunnel there is not favorable interaction between the two louvers to cause this desired drop in the internal static pressure. Other designs have employed a screen or some other drag-producing device downstream of the exhaust and upstream of the intake to achieve a drop in internal static pressure in order to cause the outside air to enter the tunnel. While this works, it is very inefficient. This results in unnecessary loss in total pressure and the attendant loss in tunnel performance. Often there is additional ducting required to control the internal static pressure which increases the construction cost. The present invention avoids these problems and achieves the desired air exchange with the lowest power loss.  
         [0110]     Referring next to  FIGS. 11,12  a deflector  1100  is placed along the bottom edge of a flier entrance  1101 , 1102  in order to reduce airflow from the flight chamber into the room  802  and thereby minimize cavity resonance in room  802 . The deflector  1100  has an angled leading edge  1103 . The leading edge  1103  inclines into the flight chamber  10  in a downstream direction. The flight chamber  10  could be round instead of a polygon as shown. Optionally a deflector  1196  could be mounted at the top of the door, wherein it bends inward into the staging area from the flight chamber.  
         [0111]     Referring next to  FIGS. 13,14  the fans  40 , 41  of  FIG. 2  are shown in their preferred design. They are oriented slightly away from each other relative to a centerline as shown. The fan planes P 41 ,P 42  are canted downstream forming acute angle P 43 . The fan cowling (fan can)  1300  has diverging walls  1302  after the segment next to the blade  1301 . Nominally W 1  may be 103 inches, and W 2  may be 122 inches. A staggering of the fans can help place the two fan cans  1300  closer together such as by moving the front  149  of fan  41  to dotted line  1499 . This reduces the distance between the two columns of air from the fans which reduces the length of the return plenum and the height. Blade  1301  could be forward.  
         [0112]     Referring next to  FIGS. 15,16  a dual return simulator  1500  is shown. Functional equivalent components to the single return simulator  1  are given like numbers, wherein no further description is needed.  
         [0113]     In this particular embodiment, the flight chamber  1503  has parallel walls rather than diverging walls in order to provide a relatively constant airflow therein. Above the flight chamber  1503  is a diffuser  1504  which connects to a double diverter  1505 . Double diverter  1505  has two diverting vanes  1507 , 1508 . Fan ductwork  1521  supports the fans  40 , 41 . Top diffusers  1520  connect to the diverters  2 , 4  as shown. A left and a right vertical return plenum  5  each has a temperature regulator system  1000 .  
         [0114]     The bottom plenums  7  each connect to a double diverter  1501 . Double diverter  1501  has two diverting vanes  1505 , 1506 . An airflow contractor  1502  accelerates the airflow into the flight chamber  1503 . A larger flight chamber  1503  can be supported with the four fans shown as compared to the two-fan embodiment of  FIG. 2 .  
         [0115]     Referring next to  FIG. 17 a  dual return simulator  1700  has a flight chamber  1701  with flier  1704  therein. The air return components  1702 , 1703  are shown with this top plan view to form a V configuration (angle  1705  is an acute angle) extending from the flight chamber  1701 . One use for this simulator  1700  is in a public pedestrian walkway PW as shown, a viewing area VA juts into the pedestrian walkway PW, while the components  1702 , 1703  are soundproofed and hidden by wall W. As noted above, the fans and related ductwork may be mounted on the roof.  
         [0116]     Referring next to  FIG. 18  another V shaped simulator  1800  is set in a different mall environment. The pedestrian walkway PW has expensive retail store space along area  1805 . Less expensive mall space  1899  may have storage areas and could house return air components  1801 , 1802 . An outside wall WOUT locates the return air components  1803 , 1804  outside as shown.  
         [0117]     Referring next to  FIG. 19 a  wall W creates an enclosed area designated as PUBLIC. Possible configurations of simulators  1  and  1500  are shown. Flying humans  1704  could create an exciting indoor amusement area designated as PUBLIC.  
         [0118]     Referring next to  FIG. 20  an artist&#39;s rendering of the simulator  1  of  FIG. 1  is shown, wherein a mall  2000  has a pedestrian walkway PW. The term “mall” herein includes a high-people density entertainment venue including amusement parks, theatre complexes, family entertainment centers, and college campuses. Ground level G 2  forms pedestal area d 1  so that the public looks up into the transparent flight chamber  10 . A ticketing area  2001  could blend in with other retail store fronts. Walls W and the ground G 2  screen components  5 , 6 , 7 , 8  are shown in dots.  
         [0119]     Referring next to  FIGS. 21 and 21 A, a two-stage airflow contractor is shown. A first stage contractor  2111  is horizontal and feeds diverter  8 . The second stage contractor  2112  is vertical and feeds the flight chamber  10 . The simulator  2110  could bury the first stage contractor  2111  underground. The result is less noise and less height for the second stage contractor  2112 . This invention can provide a lower overall height for the simulator  2110 .  
         [0120]     Referring next to  FIG. 22 a  staging area  2200  has a flight chamber  2202  with a bottom B consisting of a mesh net  2201 .  
       Cable Floor  
       [0121]     The floor of the flight chamber is a 3/32-17-strand stainless steel aircraft cable woven into a 2′×2′ (60 cm×60 cm) grid. Both ends of the cable are run through a compression spring. One hundred-twenty two (122) cables make up the tunnel floor.  
         [0122]     The compression of the springs is adjusted to give the proper “bounce to the floor providing increased safety should a flyer become unstable and fall to the cable floor.  
       Tunnel Viewing Walls  
       [0123]     There are 11 large 1¼″ (31 mm) acrylic panels which allow the controller, flyers and spectators in the staging/viewing area to see the activity in the flight chamber and flight deck.  
         [0124]     There is a large acrylic panel that allows spectators to see inside the control room. FIGS.  23 , 24 , 25  offer individual cable designs which could form mesh net  2201 . Basic aerodynamics teaches that a wing-type profile reduces drag as opposed to a blunt or flat profile. Cable  2300  has a standard twisted element core  2301  with an external helical wrap  2302 .  
         [0125]     Cable  2400  has a modified twisted element core  2401  with a single helical element  2402  missing.  
         [0126]     Cable  2500  has a modified twisted core  2501  with double helical elements  2502  missing.  
         [0127]     Referring next to  FIG. 26 a  flight chamber  10  has a flier sensor  2600  that uses energy waves  2601  (light, radio, sound, UV, etc.) to detect a flier moving too high into the flight chamber  10 . A controller  2602  may consist of simple on/off output logic, or current modulator or the like to temporarily reduce the airflow to drop the flier lower into the flight chamber. An emergency ambient door  2604  could also be opened by the controller  2602 . A mesh net  2605  may also be used to prevent fliers from traveling too high.  
         [0128]     Referring next to  FIG. 27  another diffuser  2700  might also serve as a flight chamber. The walls  2701  could be three-inch acrylic panels. The oval outlet  2702  has curved edges.  
         [0129]     Referring next to  FIG. 28 a  ship  2850  has a simulator  2801  with a seawater cooling system  2800 . A seawater inlet  2851  feeds a heat exchanger  2853  in the simulator via a flow controller  2852 . An air temperature sensor  2854  communicates to a temperature controller  2802  to keep the air temperature at a set point by controlling the flow controller  2852 .  
         [0130]     Although the present invention has been described with reference to preferred embodiments, numerous modifications and variations can be made and still the result will come within the scope of the invention. No limitation with respect to the specific embodiments disclosed herein is intended or should be inferred. Each apparatus embodiment described herein has numerous equivalents.