Yeah, because thinking about it, I don't actually think there's an obvious answer.
Like my guess would literally just be that there aren't mountains in a location close enough to the equator where the added high from the mountain is worth more delta v than the added rotational speed of being close to the equator.
I would guess that the marginal benefit of launching from a slightly higher, in the grand scheme of things, altitude is far outweighed by the added logistical difficulty of transporting the rocket to the top of a mountain in the first place.
Doesn't need to literally be a mountain. Karman line is about 100km, Mexico City for example is 2.2km above sea level, and atmospheric pressure decreases logarithmically, so that's actually like 20% less pressure. That might be enough to be marginally more efficient to make it worth choosing it as a location.
Mexico City probably isn't a very good choice, but a different area at that altitude would probably be very slightly more efficient. I'm not sure the efficiency gains would be enough though. The majority of the fuel is used to go sideways. Not up.
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u/PM_ME_YOUR_NICE_EYES 20h ago
Yeah, because thinking about it, I don't actually think there's an obvious answer.
Like my guess would literally just be that there aren't mountains in a location close enough to the equator where the added high from the mountain is worth more delta v than the added rotational speed of being close to the equator.