Sorry, my English is too bad to explain. Something you're doing wrong.
Ok. There are two ways. The first is to edit a file f-15.skins
and replace the code value = 0.6;
material = ("F15C_1", "standart", "F15C-1-07.bmp");
material = ("F15C_1_met", "standart", "F15C-1-07.bmp");
material = ("F15C_2", "standart", "F15C-2-02.bmp");
material = ("F15C_2_met", "standart", "F15C-2-02.bmp");
material = ("F15C_Numbers", "standart", "F15C-numbers-01.tga");
material = ("F15C_lattice", "standart", "F15C-lattice-01.tga");
material = ("F15C_Logo", "standart", "F15C-Logo-02.tga");
material = ("F15C_Logo2", "standart", "F15C-Logo2-00.tga");
with code value = 0.6;
material = ("F15C_1", "standart", "F15C-1-07.bmp");
material = ("F15C_1_met", "standart", "F15C-1-07.bmp");
material = ("F15C_2", "standart", "F15C-2-02.bmp");
material = ("F15C_2_met", "standart", "F15C-2-02.bmp");
material = ("F15C_Numbers", "standart", "F15C-numbers-01.tga");
material = ("F15C_lattice", "standart", "F15C-lattice-01.tga");
material = ("F15C_Logo", "standart", "F15C-Logo-00.tga");
material = ("F15C_Logo2", "standart", "F15C-Logo2-00.tga");
disappear all the inscriptions and emblems (including the tails)
The second way - this is to edit the alpha channel in the file F15C-Logo-02.tga
all that in the alpha channel is filled with black-becomes invisible