Help me with some math. It'll be fun.
I want a society on a planet or planet-like object that has multiple modes of mass transit.
T1: Something like buses -- the local. Max distance: 5 kilometers.
T2: Something like subway/metro -- the within a city. Max distance: 50 kilometers.
T3: Something like Amtrak -- go from city to city. Max distance: 500 kilometers.
T4: Something like planes -- go from one side of a continent to the other. Max distance: 5,000 kilometers.
T5: Something like intercontinental planes -- go from one side of a planet to another. Max distance: 50,000 kilometers (goes around the world)
Assumptions:
A1: For 1-5, the max time from end to another is an hour.
A2: For 1-3, assume lots of stops. Feel free to assume stops for 4-5, but explain how.
A3: For the sake of the math, assume constant acceleration or say why it is bogus.
Question: What acceleration do you need to get this to work? What amount of energy do you need to expend? What information do you need or need to make up to answer those questions? Can they all be on the ground, or is there a point at which you must fly?
is there a different shape to the world that makes this easier? Harder?
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ReplyDeletePassenger capacity? Gravity? Atmosphere density?
ReplyDeleteI think guesses can be made for many other issues, but the above paramaters could change 4 and 5 by orders of magnitude.
You mentioned shape, so I guess the question is what are the cost differences between 50megameters around the outside of a sphere around the inside of a torous? Is this the idea?
Yes, Luke Miller. Or a hypercube. Whatever you want.
ReplyDeletePax: Mass is pretty important to how much energy something takes, isn't it?
Kilograms of pax & crap, not including the ship you'll design:
T1: 2,000 kilograms (~30 pax)
T2: 10,000 kilograms (~150 pax)
T3: 20,000 kilograms (~300 pax)
T4, T5: Same as T3.
G: 1 G. Feel free to have that changes nearer or farther from the center of mass if it is fun to do so, but for my purposes we can be in a consistent 1G field.
Atmospheric density: Hmm... Oh, wow. Yeah. That's reasonably hard. You tell me, but explain why.
So, quick back-of-the envelope says that, if you’re maintaining a constant acceleration of K (positive for half the trip, negative for the other half) then your maximum speed is 50,000km / time taken.
ReplyDeleteThat should let you know how bad a problem air resistance can get / how bad debris on the track are, and so whether you need to travel through a near-vacuum.
I provide some vague estimations here - https://docs.google.com/document/d/1dARcbTRhh1RA3V22cew9O-twfHWf6hdWo7BMJCecrYo/edit?usp=sharing
ReplyDeleteThe spread sheet is here - https://docs.google.com/spreadsheets/d/1Qi2To8cVUe-D8cWYjHSsR7KF1Djip93fArf2i-V6jlM/edit?usp=sharing
In short,
T1 is a very slow bus
T2 is a reasonably light rail.
T3 is a scary fast train.
T4 is passenger version of the SR71-Blackbird.
T5 is spaceship.
docs.google.com - William Nichols' Transport Question
I'm interested in the logistics of stuff. Does A1 mean that I can get from any point to any point within 1 hour using T5? Or do I need to use T1-4 to reach a T5-station? Are the uses of T1-4 included in the hour or is each counted as a seperate trip?
ReplyDeleteJaye Foster This is faaantastic. Thanks! Was it fun?
ReplyDeleteMichel Kangro Use a T1-4 to get to a T5, like how now I take the bus to get to the airport.
ReplyDeleteWilliam Nichols yep. Much googling
ReplyDelete