Yes, I’m critiquing the plausibility of this trebuchet while ignoring the dragons.
The “Battle of the Bastards” episode from Game of Thrones introduced a new twist on the trebuchet, utilizing gravity but defying physics and logic.
It was in the background of the siege of Meereen. Blink and you’ll miss it.
Like a trebuchet, the machine utilizes gravity to propel an object toward a target. However, there are some major problems with this machine.
1.) The counterweight just isn’t enough
Instead of a traditional counterweight, there is a mini-rollercoaster that sends the entire arm down before flinging it forward. This is an adoption of a modern design affectionately named Merlin (thanks to Son_of_mogh for pointing this out).
However, the modern design was made from metal, not wood. In addition, the drop is also much higher for the Merlin design. Finally, Merlin tossed a pumpkin, not a 250-lb projectile.
Thus, in terms of the necessary force to propel an object, Game of Thrones‘ wooden creation will hardly do.
The secret of the trebuchet is that it transfers the energy from the gravity of the counterweight to the arm that hurls the projectile. An engineer of a trebuchet would want to extract as much of this energy as possible, which means using a heavy counterweight (we’re talking tons!) falling toward the earth for as long as possible.
By way of comparison, the fixed-counterweight trebuchet built at Urquhart Castle required 6 tons’ worth of counterweight just to propel a 250-lb projectile 200 yards. The trebuchets in this fantasy scene are covering much further distances. Simply put, the short drop and quick flick in the Game of Thrones‘ trebuchet would not be enough to hurl such a projectile at that speed or distance.
2.) Loading it
The next question is how do they load it? Obviously, they couldn’t lift the ball up there. There is no visible crane. Thus, the operators would need to pull the whole thing in place with ropes while the projectile is attached to the sling.
Remarkably, the lack of a counterweight makes this plausible. However, it introduces the third problem.
3.) Safety!
The projectile is ablaze in the middle of a wooden framework. How does the whole thing not catch fire while it loads and waits to launch? Is the projectile ablaze when they load the trebuchet or does someone climb up there with a torch to do the honors?
Still, in terms of conveying medievalism to viewer, this is a creative reinterpretation of the trebuchet, a distinctly medieval machine.