How does the sling work on a trebuchet?

Hi Instructables community,
I don't quite understand how the sling on a trebuchet releases.  I understand how a handheld sling works but what happens with a trebuchet sling.
Thanks guys!

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Burf5 years ago
Its basically the same as a hand held sling. But on a trebuchet, one end of the sling is fixed the the trebuchet arm and the other has a loop in it that slips over an open hook. When the trebuchet is released, the arm and sling start to pivot around the axle, when the sling reaches a per-determined position, the looped end slips off the hook and releases the projectile.
It takes some tinkering and time to adjust the hook for the best release point but generally, you want to begin where that point is approximately 45 degrees above the horizontal and go from there.
SirNoodlehe (author)  Burf5 years ago
thanks, best answer
Burf Burf5 years ago
pre-determined not per-determined.
Lore_Keeper2 years ago


rickharris5 years ago
In the drawing below the important parts are identified as A B and C

A - The Treb frame should be on wheels if the ground is hard and flat - This allows a slight movement that adds momentum to the throw and prevents the frame shaking itself to bits.

B the weight should be in the form of a swinging box so that as the arm goes over the weight maintains the perfect relationship imparting the maximum momentum to the arm

C The sling is long enough to allow the stone to lie on the platform of the treb as the arm swings it up at the top of the swing the stone will come free and pass between the ropes of the sling. This is an improvement on the fixed cup at the end of the arm because it effectively lengthens the treb arm imparting more momentum.

Vyger5 years ago
In the very early designs they had a guy with an axe try and chop it when it swung by but they had to redesign it because they couldn't find anyone willing to take the axe job. It was kind of like those special moments when someone says "here, hold this for me" and then everybody runs away.
Re-design5 years ago
When the arm first starts the loop and projectile are behind the hook/release. At the end of the swing the loop and projectile catch up with the hook and it releases.