Excellent travail!
D'ou vient l'info pour modeller le moteur et tous les autres pièces tellement en détail?

i can imagine that just grabbing and moving them on the screen is difficult whitout a plugin. But it could be a step forward for the time being that we could just use the keyboard instead of het sliders on the right.
For exemple R-key + arrows for rotating and T-key + arrows for translating, the ...

it would be much easier if you coud just select them and move them in the viewport.