90 u00b0 with a given longitudinal distance between sections fig1 a 16 b a configuration 2 with holes that follow an helicoidal path with a u201c separation u201d in the longitudinal direction and angle between holes of different sections fig1 a 17 b or a configuration 3 three holes per tranverse section with a given longitudinal distance fig1 a 18b fig1 a b illustrate one extreme end of hollow rod 803 with 2 holes 804 per transverse section 180 u00b0 apart distributed in an alternate way each set opposed at 90 u00b0 to the adjacent set of holes with a given distance between sections p fig1 a and 16b the preferred hole diameter dh is between 5 mm to 7 mm the preferred longitudinal distance between sections p is between 50 to 100 mm the preferred total longitudinal length of the zone at each extreme end that has such holes l is 3000 mm to 4000 mm with the zone comprising between 62 to 162 holes fig1 a b illustrate one extreme end of hollow rod 805 with 1 hole 806 per transverse section the holes follow a helicoidal path with a preferred longitudinal separation or pitch p fig1 b and a rotation angle from one section to the following of 120 u00b0 fig1 a and 17b the preferred hole diameter dh is between 5 mm and 7 mm the preferred longitudinal distance between sections p is between 25 to 50 mm the preferred total.