Monday, December 8, 2014

Go! Hamster Go!

We are big fans of the human hamster catapult known as Shooda Noed Beter from Elkton, Virginia. Their team motto is "Go! Hamster Go!" They are also the current world record holder, at 2048 feet, and 2013 world champion (and still champion) in the Punkin Chunkin Adult Human Powered Class. A 600 pound, 11 foot diameter, "hamster wheel" with one human hamster provides the power that loads up their catapult with approximately 30,000 Joules of energy for their pumpkin hurls.

The human hamster climbs the 11' hamster wheel

Specifications for Shooda Noed Beter, Human Powered Catapult

Adult Human Powered Class rules:
  1. Pumpkins must weigh between 8 and 10 pounds.
  2. Machines can use any kind of stored energy that can be stored by a single person in two minutes. (Energy must be stored by the power of this one person, not by other means.)...

If you are interested in the science of hurling pumpkins then you need to checkout SNB's very interesting website and dive into their year-round study of hurling pumpkins for distance.

Here is a sample of some of the topics SNB discusses:

How Strong Should a Catapult Arm Be? (Part One) (December 2, 2014)
There are a thousand different parts that can give way, and adding more power only helps you find the next weakest link in the chain. Even worse, if you're like Yankee Siege II, you run the risk of your counterweight getting so large that it collapses in on itself and creates a black hole. So, efficiency is critical for any team looking to compete at the World Championships.
Evolution of Punkin Chunkin World Records (November 25, 2014)
Ever wondered how the progress of the different Punkin Chunkin Classes stacks up? Me, too. So, here's what it looks like since 2002...

You Don't Need More Power: 3 Better Ways to Improve Your Catapult (August 26, 2014)
a wise man shared some knowledge with us our first year at the chunk. According to him, "You need 5 times more power to throw it twice as far." At first that seems non-sensical. Why wouldn't twice as much power make it go twice as far? Well, a lot of reasons, but most importantly, because that's just not how physics works...
Launch Angle (November 13, 2013)
There is a significant amount of debate on numerous forums about pin angle. There are some links at the bottom of this post that point to some very intelligent discussions about how to make the projectile go farther. I encourage you to read through them if you'd like some more information on this topic. However, we don't necessarily agree with a lot of what's written out there. First off, 45 degrees is absolutely not the right answer for any projectile not launched in a vacuum. The moment that air resistance starts factoring into the equation the launch angle must get lower to achieve optimum distance. Fortunately, most catapult enthusiasts out there bought into that concept a long time ago.

However, most of the recommendations I see still center around 40 degrees. For low speed or low profile objects, that is probably the case, but our testing indicates that at the speeds we're launching our 8-10 pound pumpkins we get more distance with a launch angle around 35 degrees. We also believe that our launch angle should get lower when we are throwing into a headwind. However, I think the key thing to take away is that you need to conduct testing of your specific machine with the actual projectiles you intend to throw in order to determine your optimum launch angle.
Shooda Noed Beter Youtube Channel (more great videos)