A vertical wind tunnel for indoor skydiving comprising: a recirculating airflow plenum; a flight chamber housed within a first vertical member of the airflow plenum; the recirculating airflow plenum including a top horizontal member , a bottom horizontal member , and a second vertical member ; a corner section arranged below the flight chamber and connecting the bottom horizontal plenum to the flight chamber , the corner section comprises a turning vane structure including a centerline forming the base of the corner section at one end of the corner section along the transverse axis of the wind tunnel and an arched member being located where the duct construction of the corner section joints the duct construction of the bottom horizontal member ; wherein the bottom horizontal member has a first section and a second section extending from the second vertical member to the first vertical member, the first section connected to the second vertical member , the second section connected to the corner section ; the first section has a generally rectangular cross section; the second section contracts the airflow between the first section and the corner section , the second section having an upper surface; the walls of the second section comprising transitions between the first section and the corner section ; the corner section contracting the airflow between the second section and the flight chamber ; the walls of the corner section comprising transitions between the second section and the flight chamber , thereby reducing the height of the recirculating airflow plenum; and the upper surface of the second section having an arched shape substantially corresponding to the arched member of the corner section extending from the centerline at least partially in the direction of the first section . a recirculating airflow plenum; a flight chamber housed within a first vertical member of the airflow plenum; the recirculating airflow plenum including a top horizontal member , a bottom horizontal member , and a second vertical member ; a corner section arranged below the flight chamber and connecting the bottom horizontal plenum to the flight chamber , the corner section comprises a turning vane structure including a centerline forming the base of the corner section at one end of the corner section along the transverse axis of the wind tunnel and an arched member being located where the duct construction of the corner section joints the duct construction of the bottom horizontal member ; wherein the bottom horizontal member has a first section and a second section extending from the second vertical member to the first vertical member, the first section connected to the second vertical member , the second section connected to the corner section ; the first section has a generally rectangular cross section; the second section contracts the airflow between the first section and the corner section , the second section having an upper surface; the walls of the second section comprising transitions between the first section and the corner section ; the corner section contracting the airflow between the second section and the flight chamber ; the walls of the corner section comprising transitions between the second section and the flight chamber , thereby reducing the height of the recirculating airflow plenum; and the upper surface of the second section having an arched shape substantially corresponding to the arched member of the corner section extending from the centerline at least partially in the direction of the first section . <EOS>