I have to agree with Dawid a projector is only suited for flat surface and eve then you risk distortion if yo got the angle wrong on a rounded surface you will get a distortion no maat what
I fully understand but if I do photo realism on a tank I use the old school trace methode and correct the distortions you get by putting a flat reference to a round surface by hand and eye , doing it this way you get a much better result than using a projector to trace the ref . a projector wont correct the distortions for you