Monday, September 19, 2011

How To Build A Spaceship - Part 1

1961 Ferrari 250 GT California
So you wanna build a spaceship, eh? Well, first we are gonna need a car. A Ferrari, in fact.

That's what we'll use for this little opening metaphor, anyway. Don't worry, it will be a lot more fun than a typical "If Train A leaves Chicago at 50mph..." story problem. This metaphor will get us into space!

Let's say you want a fun road trip from from Los Angeles to New York City. Being a curious and thrifty person, you also want to know how long it will take and how gas you'll need. To determine these things, you need to figure out a bunch of other things. We'll simplify our trip (this is, after all, just a metaphor) and say that you will drive non-stop, Smokey And The Bandit style. We will need to know how far it is from LA to NYC, how fast your car can go, what kind of gas mileage the car gets at that speed and how much gas the car's fuel tank holds. We're going to say "who cares" to the cost of both gas and car and "borrow" a car, Ferris Bueller style.)

So here are the things we can find out after a quick bit of Googling:
  • Distance from LA to NYC = about 2800 freeway miles
  • Average speed = 65mph (estimated most efficient speed for bright red Ferrari or Black & Gold Trans-Am. At higher speeds, the lost time due to traffic tickets and possible loss of license would hurt our overall travel time too much.)
  • 1961 Ferrari 250 GT California fuel mileage = 16 mpg
  • Size of Ferrari fuel tank = 31.7 gallons
We can plug that info to plug into a few simple equations, and find:

Time = 43 hours
Fuel used = 175 gallons
Refueling stops = 5.5 stops to refuel

So let's put all those shiny numbers together. It will take us 43 hours to get to NYC. No, wait! We need to add the time it takes to stop at the gas station. We can't really make a half of a stop, so we'll round up to 6 fuel stops. Say about 10 minutes per stop, so that adds an extra hour. So our final numbers are:

LA to NYC Ferrari Road Trip:
Time = 44 hours or 1 Day and 20 hours
Fuel used = 175 gallons
Refueling stops = 6 stops to refuel

Now let's mull over those final numbers for a second. First, they assume we are capable of staying awake for nearly two days straight, or that we have a co-driver to help out. Second, we'll probably get pretty hungry and thirsty since there is no money in the budget for food or drink. Third, while the fun-factor may be high, cruising from LA to NYC in a 50 year old convertible Italian sports car is not the most efficient way to go cross country. Much of its 160mph top speed is wasted. A less glamorous, more reliable modern econobox would easily fulfill our 65mph average speed, get much better gas mileage, and have a lower probability of breaking down in the middle of nowhere. And if it did break down, it would be guaranteed easier, cheaper and quicker to fix than an antique Ferrari. The old Ferrari also doesn't have much room, and hopefully it won't be raining somewhere along the trip (we're traveling with the top off, naturally.)

But, the numbers do give us a pretty good rough estimate of time and cost. And they also give us a pretty good starting point if we want to modify some of the parameters. For instance, if we really needed to make the trip fast, we could double our average speed to 140mph. Our fuel mileage would go down, and our cost and number of fuel stops would increase, but we'd still get there in less than a day. At least we'd get the satisfaction of using most of the capabilities of the high performance Ferrari, even if we still sacrificed in the areas of cargo space and overall cost.

So what does this have to do with building a spaceship? First, let's imagine that we're writing a science fiction story for an audience living in the year 1860. Our heroine will drive a "horseless carriage" from LA to NYC. If we said she drove north at 1000mph and arrived in New York in five minutes, our audience would laugh. Even an audience with an 1850 tech level would realize our storyline is laughably rediculous. They are familiar with locomotives and how far California is from New York. Our story just isn't "plausible." However, if instead we wrote about our red "sports car" that took our heroine at the blazing speed of 65mph eastward on the "freeways" to NYC in less than two days, it might seem far fetched, but at least on the edge of possibility.

To come up with a "realistic" spaceship, we'll need to use the same kind of logic as we did with our road trip. Only instead of driving a Ferrari to New York, we'll use a spaceship with artificial gravity and a Magnetoplasmadynamic (MPD) drive that travels to Mars. Believe it or not, we'll use design elements from existing NASA studies. We'll use these design elements to determine some need-to-know numbers (similar to our Ferrari Road Trip's distance, speed and fual miliage, etc.) and plug them into some simple equations to figure out how fast our ship will go and how long it will take to get to the Red Planet.

Now that you've warmed up with the Ferrari Road Trip, you're ready to use that knowledge for some cool Rocketpunk calculations for a little jaunt to Mars.

Tune in next time for How To Build A Spaceship - Part 2!

Other parts of this series:
How To Build A Spaceship


  1. I used NASA to build mine. They're very handy.

  2. Yep, they sure are :) It's amazing what cool designs they come up with. Hopefully some of them will actually get funded and be built one day!

  3. This sounds hard. Can it be completed by a novice DIYer over the weekend?

  4. Hey Lindsay - yes, it can :) The fun begins in Part 2...