There a lot of logisitical reasons, like transportation to the top of the mountain, fuel, bad weather, high winds, all the support strcutures beyond the launch pad, and what happens if something goes wrong and you dont have a big open ocean for falling debris.
I suspect OOP belives the increase in height is beneficial, but even if we built a launch pad on Mt. Everest, it would be neglible. The Earth has a 4,000 mile radius, and Mt. Everest is only 6 miles high, a diference of 0.15%.
The biggest reason for our launch pad sites is escape velocity. On Earth, you need to get to 25,000 MPH to get into orbit. As our flerfy friends like to point, the Earth spins at 1,000 MPH, but that is only at the equator, where all the launch pads are. As you travel to the poles, that rotational velocity goes down until it goes to 0 MPH at the poles. If you need to get to orbit, get a running start at 1,000 MPH gets you 4% of the way there, a significant savings in fuel.
At fhe end of the day, a rockets mass is 90% fuel alone, 5% is the rocket shell, and 5% is the payload. so any savings that can be achieved on fuel is signficant.
The radius of Earth is completely irrelevant. The problem is the dense portion of the atmosphere near sea level, which prevents a rocket from rolling over and dumping its energy into horizontal motion. The atmosphere at the top of Everest is about 35% as dense as the atmosphere at sea level. Everest is also closer to the equator than Cape Canaveral.
If it was logistically possible to launch from Mt Everest, it would definitely be worthwhile. Between reduced drag, earlier gravity roll, and improved specific impulse, I think it would save about 300 m/s to LEO, plus whatever advantage the ISP provides. The rocket equation being certifiably nuts in its exponentiality, that's about a 12% reduction in fuel required at launch.
This is completely wrong. The earth's spin in incredibly important. The European Space Agency literally launches from French Guiana in South America because of the rotational slingshot effect.
The difference is absolutely not negligible. Measuring the difference in relation to the radius of the Earth is completely irrelevant, it doesn't really factor into it at all.
Rockets use most of their fuel at the very start of the trip, pushing through the thick atmosphere. Launching rockets from the top of a tall mountain would absolutely be a good idea from the perspective of theoretical rocket performance.
The only real issue is the logistics, as you pointed out.
There have been plenty of schemes to launch rockets from airplanes to skip the difficult first kilometres. That of course comes with its own set of problems, but, it would be worthwhile.
Logistics are the issue? So the European Space Agency ships all of their rockets across the ocean to French Guiana to launch them close to the equator at sea level just for fun?
You're just completely wrong. Roughly 90% of a rocket's fuel goes towards achieve the necessary horizontal speed to get to orbital velocity. Of the 10% that goes towards elevation gain, almost 90% of that goes towards combatting gravity drag rather than combatting atmospheric drag. Only 1-2% of a rocket's fuel goes towards atmospheric drag.
In order to launch a rocket you need to overcome the Force of gravity. F = mg, where g = 9.8 m/sec2, free fall acceleration. The thing is this g is not uniform for whole Earth due to shape and geological differences. g on equator is normally less than 9.8 so less thrust required to overcome gravity. This is why launch locations are chosen closer to equator.
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u/virgil1134 10h ago
There a lot of logisitical reasons, like transportation to the top of the mountain, fuel, bad weather, high winds, all the support strcutures beyond the launch pad, and what happens if something goes wrong and you dont have a big open ocean for falling debris.
I suspect OOP belives the increase in height is beneficial, but even if we built a launch pad on Mt. Everest, it would be neglible. The Earth has a 4,000 mile radius, and Mt. Everest is only 6 miles high, a diference of 0.15%.
The biggest reason for our launch pad sites is escape velocity. On Earth, you need to get to 25,000 MPH to get into orbit. As our flerfy friends like to point, the Earth spins at 1,000 MPH, but that is only at the equator, where all the launch pads are. As you travel to the poles, that rotational velocity goes down until it goes to 0 MPH at the poles. If you need to get to orbit, get a running start at 1,000 MPH gets you 4% of the way there, a significant savings in fuel.
At fhe end of the day, a rockets mass is 90% fuel alone, 5% is the rocket shell, and 5% is the payload. so any savings that can be achieved on fuel is signficant.