What is hurling?
Hurling is the art and science of throwing anything with a hurling device.
A nice description of why to hurl is found in Craig's Essay on the benefits of hurling.
What is a hurling device?
A hurling device is any machine built to throw projectiles. Some people consider all hurling devices catapults, but the term catapult is quite unspecific and poorly defined so it is usually avoided here. There are many types of hurling devices; most hurling devices fall under one of two categories, torsion or trebuchets (great videos on both these pages!). There are other types such as sling shots and rubber band spoon-a-pults but these are less commonly perused by the hurling community.
Where do I start?
This site is probably the best starting point around. While it may not have the information you need it has links to many other great sites. Once you have wandered around on this site, and looked at some others you may know what type of device to build assuming you want to build one. If you want to build a device but have not decided what kind, the first thing to consider are your goals and restrictions. To form a list of goals and restrictions you will have to ask yourself several questions, some of which are listed below. If you are having trouble getting started, or construction challenged, a kit can be a fine way to start. A good starting point would be the SPECK from RLT.
Form a list of goals
To make a meed your goals, you must first form them!
- What are the limits?
- Size limits?
- Cost limits?
- Range limits?
- Materials limits?
- Time limits?
- What are your abilities?
- Can you cut metal?
- Can you weld?
- Are you good at wood working?
- Can you get help from people with these skills?
- What are your resources?
- What materials can you buy?
- What materials do you have?
- What tools do you have?
- What do you want to maximize?
- Ease of use?
- Penetrating power?
- What will you throw?
- Golf balls? Bouncy balls? Tennis balls? Baseballs? Pumpkins? (etc.)
- How much will it weigh?
- Roughly how far do you want to throw it?
- What do you want to minimize?
- What power source would you like to use?
After answering as many of these as possible you should have chosen a projectile. Choosing a projectile, or a few ones of similar weight is a great thing to do early in design, but it can be changed later. You should now also be able to come up with a set of goals for your machine. An example set of goals and requirements/limits is below ranked from most important to least:
- Power with gravity.
- Throw a golf ball around 100 yards.
- Maximize range.
- Easy or no assembly.
- Minimize size.
- Minimize weight.
- Made with mostly supplies I have (3/4 inch lumber)
- Fit in car disassembled (3 feet*2 feet*2 feet)
- No welding and minimal metal work.
Your lists can be very general to extremely specific. The one above could be considered specific. Both work well. The list can often be a vague mental list, but writing it down will help especially if you need to ask for help with your design because you will not be able to be helped much until a rough list is provided.
Choosing device type
This can be one of the hardest parts and depends greatly on the situation. Below is a very rough guide to choosing a device type based on several different factors, but also look at some pictures and video to see what you like. You can also see an essay on the comparison at Craig's Site. If you are still not sure what device type you want to build and would like help ask for advice on The Hurl by posting a new topic and describing your situation. Be sure to include your goals and requirements as described above.
Choosing your device type is easy if you know your power source. If it is torsion your type is torsion, if the power source is springs or gravity your type is trebuchets. The device type is mainly the power source choice.
Size vs. Range
If you want something small that will throw very far you will likely want torsion or possibly a spring trebuchet or an advanced modernly invented trebuchet such as a king arthur or whipper. These devices can usually exceed 100 arm lengths in range, and sometimes more than 200 or 300. This extra range for the size does come at the cost of complexity and frame stress which means more labor, design and materials will be needed and often more problems will be encountered.