to form a loop on the surface of the second laminated structure 2b in the manner as described reinforcing base material for the intended i shaped spar 3 is formed the invention will now be described in more detail first the first textile filament y1 is laminated in the region where said first filament guide tubes g1 are disposed in the order of layout shown in fig3 a and b that is the first textile filament y1 is disposed in a substantially horizontally disposed zigzag pattern in a first layout plane sa1 defined by the x and y axes thereby forming a first layout layer la1 of the first textile filament y1 shown in solid line in fig3 a then the layout arrangement is shifted to a second layout plane sa2 overlying the first layout layer la1 a second layout layer la2 of the first textile filament y1 is formed as shown by the dotted line in fig3 a thereafter the first textile filament y1 has its layout layer position shifted to a third layout plane sa3 overlying said second layout layer la2 the first textile filament y1 is then positioned along the y direction as a y axis oriented filament in the.