What is Squirrelpower?
My friend Mark and I got into a discussion about the absurdities of the measure of horsepower. Why did James Watts use the horse to determine the power of an engine? Since we know the power a horse makes, why couldn’t you deduce the power of other animals? I have an affinity toward squirrels, and the shop in which we started the RWD Talon project in had an awful lot of furry squirrely friends who stopped by and stared at us while we were working on the car (Lansing, Michigan is literally covered in squirrels!) Anyway, with the thousands of hours we spent in that shop working on the car, we end up coming up with a few great ideas, and a bunch of useless dumb ideas, too. The Horsepower to Squirrelpower conversion is one of the more mathematically complicated ideas we came up with. Mark and I used different methods for computing squirrelpower, and we both came up with surprisingly similar results:
Our Method
It was quite hard to come up with a way to compute squirrelpower. I mean, the biggest challenge wasn’t the math required, but actually finding statistical information about squirrels. How much do they weigh? How much power can they produce? Even on the Internet, these things are a mystery. I did happen to find some little bits of information about them from
http://www.squirrels.org/faq.html: “There is an old story of an Illinois state police officer that once clocked a gray squirrel, with his radar gun at 20 mph. as it ran across a highway. Other research has confirmed similar speeds for squirrels.”I also found information about the average weight of a squirrel – it weighs 1.2 pounds. Given the average weight of a squirrel, and the top speed of a squirrel, I figured out that an average squirrel can generate .0007492446677193555 bhp. That means 1334.677 squirrels can produce one horsepower!
Mark’s Method
For those of you who don’t know Mark, he’s a geek. Here’s part of an email I got from him about squirrelpower:
We all know that 1hp = 746 watts, but the definition that’s going to be more useful for this conversion is 1hp = 33,000ft-lb/min. That’s 33,000 pounds times feet per minute, originating in the arrangement where horses were used with ropes and pulleys to lift rocks out of mine shafts – 330 lbs lifted 100 feet in one minute, or theorhetically 33 lbs 1000 feet or 3300 lbs 10 feet – you get the idea. So if we can figure out a meaningful measurement of weight over distance per unit time with a squirrel, we can totally translate it up.
So, he had a strong thesis statement. Unfortunately, he didn’t find the information I found about squirrels. So, based on body mass alone, Mark determined that:
I don’t think we’re going to be able to generate an accurate squirrelpower figure 🙁 Basically, I’ve not been able to find any data to indicate how much weight a squirrel can lift, pull, or carry. I don’t imagine many people have bothered to measure this. We could always use body mass to equivalate them, in which case 1hp ~= 1100sqp.
Summary
Because our completely different methods for computing Squirrelpower came up with surprisingly similar results, we decided to take our numbers and choose the average of the two. This gives us 1217 squirrels per horsepower. But, since squirrel weight varies by season, and sometimes we see some really fat squirrels, and to come up with something a little easier to compute, we chose to round down to the nearest 100 squirrels. So, the number we chose is 1200.
That’s right – based on math, geekness and subjective thinking, 1200 squirrels can do the work of one horse! This also means that the goal of the Talon is to produce just over one million squirrelpower!
