How does a catapult work?

Before we go into the working of a catapult you had to understand that catapult is actually the type of the weapon and not the actual weapon because catapult is that technology which uses a projectile which is aimed at the enemy and it is released because of the tension in the wire which is holding it back and any kind of catapult weapon uses gravity, tension, torsion.

The older catapult weapons are hardly used in these days but in the earlier days they used to be used extensively to inflict the first attack on the enemy so that the important units of the enemy whether they are the artillery units or manual units would be inflicted a great damage the giving a big blow to the moral of the enemy right at the start.

Some of the most famous types of catapult weapons are trebuchet, onager and mangonel.

While the working mechanism of all of these catapult weapons is different but the basic principle is the same and that is of the catapult physics.

Basics of catapult physics:


The basic working of the catapult revolves around the tension and certain part of the weapon and that part can be a piece of wood or it can be a rope which is twisted and therefore when the tension is released on the rope or on the spring, or wooden block and it allows the machine to throw the projectile along a predetermined angle and the range of the weapon depends upon the tension in the rope or the piece of wood and it also depends on the weight of the projectile as well and the incoming winds.

Since most of the catapult weapons are capable of shooting from a great distance they can inflict damage on the enemy without being inside of the enemy. The distance which is covered by the projectile as we mentioned above depends on the energy which is stored in the form of tension in the twisted rope or in the piece of wood.

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You can compare this tension to that of a bowstring which is used to shoot a bow.

Below we would be speaking about the individual types of catapult weapons.

Each of them has a similar mechanism but the structure varies depending on the range which is to be covered and the type of projectile.

Catapult weapon-The trebuchet:

This was the most widely used catapult weapon during the ancient times and it was often used to break the walls of the fort of the enemy. The reason that it was the most widely used catapult weapon is because it is a great consistency as compared to the other catapult weapons because the amount of energy which can be transferred to the projectile can be kept constant time and again and therefore if you have set the angle according to the target then you can head the exact same target again and again and this can be very useful when you are trying to break a wall or when you’re trying to break a guard tower.

This catapult weapon uses the principle of mechanical advantage and it actually consists of a lever which is a fulcrum which is more nearer to the counter balancing weight then to the projectile which is to be launched and the projectile is placed in the sling.

In order to place the projectile the lever is actually more down and therefore this works against the gravity which is acting on the counter balancing weight and since the counter balancing weight is much greater than the rate of the projectile when the sling is released and the liver is allowed to move along with the gravity the counterweight comes down at a far greater force and this causes the projectile to come out of the sling and to get shot at a distance which is directly proportional to the counterweight which is at one end of the lever.

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This is the basic working mechanism of the trebuchet.

Catapult weapon-The Mangonel:

this catapult weapon actually consist of a arm in which the projectile is placed and the angle of the arm is controlled by the crossbar which is placed at the centre of the arm and therefore you can change the place of the crossbar to decide the angle at which the projectile is launched and depending on this you can also calculate the distance which would be covered by the crossbar as well.

The speed at which the projectile is launched depends on the velocity of the arm.

This type of catapult mechanism was actually used to destroy walls since this is a horizontal projectile arc as compared to the trebuchet which used to launch projectiles from a far greater distance and these would not have a horizontal projectile arc.

The energy efficiency of this type of catapult weapon is on the lower side because the arm is actually reaching a very high velocity during the launch but the same is not being transferred entirely to the projectile and that is why there is a vestige of energy and the only way in which this vestige of energy can be minimised is to make sure that the arm is made from a lighter material but you had to also understand that the arm is made from such a material that it is able to handle the pressure of the crossbar as well as the projectile during the launch.

For the launching of the projectile the arm of the weapon is actually dragged down with the help of a rope.

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Due to the pulling down of the arm there is tension in the arm because it is tilted from its normal position and therefore as soon as the rope or the material which is holding the arm back is released the arm starts to move back into its normal position with the help of a cantilever type of assembly and the speed at which the arm was back to its original position is very fast and this is what gives velocity to the projectile.

This is the basic working of the Mangonel.

Catapult weapon-The Onager:

The Onager
The onager is similar to the trebuchet with only one difference that is instead of the counterweight being placed on other side of the lever there is a higher torsion material which is being placed on the other side of the lever. Since the amount of energy which can be stored in the higher torsion material can change it is not as consistent as the trebuchet.

Catapult weapon-The ballista:

The ballista
The ballista is nothing but a large crossbow. The rope which is used as a twisted rope to produce higher amount of tension. It is used to throw rose as well as peers and since Crossbow is are famous for their accuracy the aim can be set very precisely as well. It can also be used to shoot projectiles of various measurements.

These are the most famous types of catapult weapons which were used in the earlier times and some of which are even pretty popular today.