3D Animation size problem

Hallo people

I have been using Matlab for a week and have the task of programming a 3D figure. The figure must consist of several small figures and I have already managed to program two small figure, but I have a problem with the size when I start the program, the figure comes very zoomed and I have to zoom in every time.

Hauptkoerper_Flugzeug = struct ();

Hauptkoerper_Flugzeug.Groesse =1;

P1 = [1 0 0];

P2 = [2 0 0];

P3 = [2.5 1 0];

P4 = [2 2 0];

P5 = [1 2 0];

P6 = [0.5 1 0];

P7 = [1 0 9];

P8 = [2 0 9];

P9 = [2.5 1 9];

P10 = [2 2 9];

P11 = [1 2 9];

P12 = [0.5 1 9];

P13 = [1.5 1 12];

P14 = [0.5 1 0];

P15 = [0.5 1 7];

P16 = [-2.5 1 0];

P17 = [0.6 0.8 0];

P18 = [0.6 0.8 7];

Hauptkoerper_Flugzeug.Ecken = ([P1;P2;P3;P4;P5;P6;P7;P8;P9;P10;P11;P12;P13;P14;P15;P16;P17;P18]-0.5)*Hauptkoerper_Flugzeug.Groesse

F1 = [1 2 8 7 1 1];

F2 = [7 1 6 12 7 7];

F3 = [12 6 5 11 12 12];

F4 = [5 11 10 4 5 5];

F5 = [4 10 9 3 4 4];

F6 = [3 9 8 2 3 3];

F7 = [1 2 3 4 5 6];

F8 = [7 8 9 10 11 12];

F9 = [7 8 13 7 7 7];

F10 = [8 9 13 8 8 8];

F11 = [9 10 13 9 9 9];

F12 = [10 11 13 10 10 10];

F13 = [11 12 13 11 11 11];

F14 = [14 16 15 14 14 14];

F15 = [16 15 18 16 16 16];

F16 = [16 14 17 16 16 16];

F17 = [16 17 18 16 16 16];

Hauptkoerper_Flugzeug.Flaechen = [F1;F2;F3;F4;F5;F6;F7;F8;F9;F10;F11;F12;F13;F14;F15;F16;F17]

plot3(0,0,0)

grid on

patch('Vertices',Hauptkoerper_Flugzeug.Ecken,'Faces',Hauptkoerper_Flugzeug.Flaechen,'FaceColor','red')

axis equal

a=Hauptkoerper_Flugzeug.Groesse * 1.5;

axis ([-a a -a a -a a])