Re: Optimal location of world capital

On Thu, 28 Feb 2008 11:09:48 GMT, Tim Tyler <seemysig@xxxxxxxxxxxxxx>
wrote:

Derek Lyons wrote:
John Mianowski <spamfree@xxxxxxxxxx> wrote:

Launching Eastward gives you the speed of the Earth's rotation (almost
1000 mph @ equator) in your favor. Launching Westward, you'd have it
working against you.

That was a Big Deal back in the stone ages of the 1950's. Like so
much else that was a Big Deal back then, it is essentially meaningless
now.

That is nonsense - e.g.:

``An object on the surface of the Earth already has an
eastward velocity, because of the Earth's rotation,
but it is much too small: 409 meter/sec on the equator,
and 409 times cosL at latitude L. That is much too small
to fling you or me into orbit (for which we ought to be
grateful), but it's still something, and satellite
launchers, eager to make use of the smallest advantage,
fire their rockets eastward. At Cape Canaveral you get
a bonus of about 360 m/s.''

Yes, and with a stock Delta IV Medium running empty you get a
delta-V of 14,000 m/s. Meanwhile, you only need about 8,000 m/s
of delta-V to reach low Earth orbit.

How meaningful is ~400 m/s, give or take, to a vehicle that
has 6,000 m/s more delta-V than it needs to get where it's
going? A modest change in the payload that can be carried
and still make orbit, sure, so maybe "essentially meaningless"
is overstating things a bit.

But:

Delta IVM, from KSC to LEO, launching East: 8825 kg payload
Delta IVM, from KSC to LEO, launching North*: 7800 kg payload
Delta IVM, from KSC to LEO, launching West*: 6820 kg payload

* Neglecting the fact that this will drop rocket parts on
inhabited areas

and to get back to the original question,

Delta IVM, Equator to LEO, launching East: 8975 kg payload

So if you're planning to build a spaceport, I suppose you might
want to put it on the equator, if it isn't too inconvenient, which
it usually is. If you're planning to build a World Capital, I
don't think you're going to misplace an entire city by thousands
of miles, just to squeese an extra hundred fifty kilograms onto
each rocket that you for whatever reason decide to launch from
your capital.

Heck, even if your otherwise-optimal World Capital Site can only
launch rockets due West, you'll still do OK, and you certainly
won't need multiple extra rocket stages or any such thing.


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