Designing an Onager Catapult: Tips and Tricks for Optimal Performance

In summary: Code=as2&camp=1789&creative=390957&creativeASIN=B005HF42XYIn summary, the expert thinks that the long thin ropes are probably the best option because they give the user more torque. They also suggest using thick ropes because they will not be able to pass by the arm easily. They suggest creating a locking mechanism and place it where the user desires. They also suggest using a round arm over a rectangular arm because it is probably better.
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TofuBoy
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Hi! I'm making a onager for a project and so far I'm not having much luck! My Onager has to fit inside a 0.5m x 0.5m x 0.5m cube, and it will be throwing tennis balls.

I've been browsing around a few nights already and found this topic, which has helped me the most by far: .physicsforums.com/archive/index.php/t-155437 (please add "www" in front and ".html" at the end, I can't post links :cry:)

But there are a few things I still don't quite grasp.

1. Long thin ropes vs Short thick ropes, which one would give me more torque?

I'm guessing it's the long thin ropes because most pictures I've seen use those.
I'm using really thick natural fibre ropes right now I can only have two pass-bys on the arm with 3 full-revolution twists on each side.​

2. How would I get the sling to release the at 45 degrees like the one in this picture?
.onager.net/pict12 (please add "www" in front and ".jpg" at the end, I can't post links :cry:)

This just befuddles me

3. How would I make a locking mechanism and where do I place it?
I attempted a few ones but only to end in failure --it was either too weak or I couldn't pull it to release it.

4. Round arm vs Rectangular arm
Would it be better to have a round arm like most of the Onagers I've seen? I'm not sure if it would help with anything.

I'm currently using a rectangular arm with two nails on the side to secure it in the rope​


Any help would be MUCH appreciated!
I'm getting a headache from trying to figure these things out​
 
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1. How does the weight of the projectile affect the performance of the onager catapult?

The weight of the projectile plays a crucial role in the performance of the onager catapult. A heavier projectile will require more force to launch, resulting in a slower and shorter trajectory. On the other hand, a lighter projectile will require less force and can travel farther. It is important to find the right balance between the weight of the projectile and the capabilities of the catapult for optimal performance.

2. What type of materials should be used for constructing an onager catapult?

The materials used for constructing an onager catapult should be strong, durable, and flexible. Wood, such as oak or ash, is a common choice for the frame and arms of the catapult. The throwing arm should be made of a flexible material, such as rope or sinew, to store and release the energy efficiently. It is also important to use sturdy materials for the base and support structure to ensure stability during use.

3. How can the tension of the throwing arm be adjusted for optimal performance?

The tension of the throwing arm can be adjusted by changing the position of the sling and the length of the rope or sinew used for the arm. The closer the sling is to the pivot point, the greater the tension will be, resulting in a stronger launch. The length of the arm can also be adjusted to fine-tune the tension. It is important to experiment and find the optimal tension for the desired distance and accuracy.

4. What is the best angle to launch the projectile from an onager catapult?

The optimal launch angle for an onager catapult will depend on the weight and shape of the projectile, as well as the tension of the throwing arm. Generally, a launch angle of 45 degrees will result in the farthest distance. However, it is important to experiment and adjust the angle for the best results. A lower angle may be more suitable for shorter distances, while a higher angle may be better for accuracy and hitting a specific target.

5. How can the onager catapult be calibrated for consistent performance?

To calibrate an onager catapult for consistent performance, it is important to keep track of the variables that affect its performance, such as the weight of the projectile, tension of the throwing arm, and launch angle. By recording and adjusting these variables, the catapult can be calibrated for consistent launches. It is also important to regularly maintain and repair any worn or damaged parts to ensure optimal performance.

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