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Sea Dragon
The very large rocket was probably Sea dragon and the advantages were more on allowing a massive vehicle to be built at all rather than inherent advantages in starting underwater.
(image credits)
Building the launch vehicle on a slip way and floating it to the launch site bypasses a number of size constraints in building and moving large ...
20
The center of the Earth is, for any reasonable approximation, in one of the focus points of an elliptical orbit. For a circular orbit, there is only one focus point, so the center of the Earth is in the center of the orbit.
The plane of the orbit thus would intersect both the center of the Earth as well as the launching site.
If the launch site was on the ...
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The short answer is that a spacecraft is attracted to the center point of the earth, not to the earth's rotational axis.
[I]t would make sense to me that launching east would result in a 0° inclination with the orbital plane raised so it's parallel to the equator but above or below it.
Here's one explanation of why that wouldn't happen that you might ...
8
You might be thinking of the Sea Dragon project, although this never got past the conceptual / early planning stages.
Some of the advantages of a sea launch are that you can be far away from habitation and the water can provide cooling and acoustic damping during launch.
But the disadvantages are also serious. You are even more at the mercy of the weather ...
8
Early in the development of the Polaris missile system, there was a lot of work on launching a missile from underwater.
Polaris was a nuclear deterrent to rapidly launch multiple missiles from a fully submerged submarine. Staying submerged until a boat-load of launches were complete was a key goal: the boat was to be very difficult to track and destroy ...
7
Molniya orbits
As written by Aurovrata
Plesetsk is actually ideally situated to launch satellites into
Molniya orbits, and as a result saw many more launches than Baikonour.
A or better THE molniya orbit has an inclination of 63.4°.
The lauchpades are located about 62.9° N.
So launching nearly straight east (which gives you the maximum input from ...
7
Earth's gravity pulls you towards the centre of the Earth, so if you're above Kennedy, that pull has a Southwards component, as well as the component towards the Earth's axis. So your path curves South, so that in the end the orbit spends equal amounts of time North and South of the equator, and the pulls in that direction balance out over time. All orbits ...
3
As you correctly noted, the S he's using is a combination of effective surface area and drag coefficient. All literature I've come across uses S for surface area and expresses drag as $D = C_D\frac{1}{2}\rho V^2S$ where $C_D$ is the drag coefficient and S is the effective surface area.
Combining these two into one parameter makes sense to me however. $C_D$ ...
3
Launching from international waters.
In addition to the factors mentioned in other posts, there's an additional benefit from launching from the ocean: you can launch from international waters. This could be handy if you're launching a rocket that uses some form of material or process that is illegal or heavily regulated for civilian use in your home country....
2
Reductio ad absurdum
If you could choose freely on which circle to orbit, the most convenient place to take off from would be the North pole. That would set the circle diameter to zero. You would then climb to whichever altitude you pleased and remain there, immobile in space, for as long as you wanted. How cool would that be?
An attempt at analogy
In ...
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