From a very quick overview it seems to me that you have your coordinates wrong. In order to have a tail sitter they should surely have the z component constant (usually negative).
For general purpose I usually use 3 points at 120 degree from each other with z constant.
I think they should look like
V1= 0 , +y , -z
V2 = +x , -y , -z
V3 = -x , -y, -z
I d use trigonometry and say
V1 = 0, radius , z_offset
V2 = radius*sin(120), radius*cos(120), z_offset
V3 = radius * sin(240), radius *cos(240), z_offset
Pseudo code written from mobile phone...
Thank you!! I used z-offset = -78