I made a trebuchet but have no clue of how to add the projectile and launch it.
guys pls help…
First of all your work and simulation looks great. I don`t like the model. To me the counter weight is placed much to high and makes physical sense. It is just because my friends and me did a real one based on historic “blueprints”. It was about 5 Meters in hight and worked for some years… it was grazy fun 
after a woodpecker destroyed the arm. However…The Rope in your sim is not behaving ralistic. But looks quite well.
Back to your question…
Maybe first add or fake a double rope how it is in reality. Then you can maybe parent an empty to the “Projectile holding” part or vertices of the rope. Use that Empty to parent the “projectile” on it. Do it by constraints an disable that constraint during physics simulation. Good luck!
sorry for my late reply. we got a local electrical shutdown right here due to bad weather.
um…i actually got the way how to do so. i just attach the projectile to the rope by giving vertex group and let it swing over the trebuchet. then i copy the projectile and make it invisible before launch it to the air.
nice way to solve it. think you are on the right way. 
