To be fair, it’s not the cost of the fuel itself that is an issue for rocket launches, just that so much of it is required, and it adds so much weight to the rocket. Fuel is less than 1% of the cost of a rocket launch, yet typically over 90% of the mass of the entire launch. If you could somehow spend fuel on the ground moving things to an optimal launch point to have to put less fuel in the rocket, it would absolutely be worth it.
The real issue is that launching from a mountain would not save you much fuel anyways. To get to orbit requires you to go very fast sideways. The initial “upward” part of a launch is just to get past the thickest part of the atmosphere, then it quickly pivots sideways for the majority of its journey.
You save more fuel by launching from a lower altitude closer to the equator, where you can take more advantage of earth’s spin to gain additional sideways velocity. So we do spend a lot of fuel to do this, for example SpaceX manufactures their rockets in Hawthorne, California, where there is a lot of aerospace manufacturing expertise, and spends a lot of fuel to ship them to Cape Canaveral, Florida, which is closer to the equator.
The radial difference between equatorial sea level and the peak of Mt Chimborazo is about 0.1%. It provides very little benefit but would be a logistical nightmare to launch from.
We'd be better off building a electromagnetic launcher up the side of it and then we can put everything at the bottom and save fuel by using solar wind and nuclear to juice the em rails.
You'd have to engineer the payload to withstand ridiculous acceleration. No big deal if the payload is a HILE projectile but if you have living things or moving parts, that can be trickier.
that's only for a cannon, for an installation like that we could make it pretty long to keep the acceleration g's down, don't wanna hit max q while still on the ground.
Acceleration as you head up is one part of the problem, but deceleration as it leaves the tube and hits the atmosphere is another. The faster you go, the more friction slows you down. Trying to get productively much speed in that situation is tough.
Okay so I used AI for this, so take it with a grain of salt, but to accelerate a projectile at a constant 4.5G and have it reach escape velocity, at the end of the barrel, you'd end up with a ~720km cannon.
Doesn't need to reach escape velocity... Any velocity you reach is less fuel having to be carried and spent in later stages, so more payload. You could compare costs of building such a launcher or just grabbing a plane and take it 20,000m high and also give it a spin. I'm not a rocket scientist (unless Kerbal gives you a degree lol) but I guess nobody is willing to spend that much for a reason.
0.1% of what???
It's definitely past more than 0.1% of the air molecules.
15 PSI at sea level, 7 psi at the mountain top. For every square inch of cross section on your rocket, instead of having to push 15 pounds of air out of the way, it's down to 7. That seems like >50% improvement?
Yeah but you spend more time fighting gravity when you keep things slow enough that the vessel doesn't rip apart when travelling through soup. Fwiw Im kerbal trained only
Things dont move fast enough through the atmosphere to lose their structural integrity. These spacecraft can handle forces of greater than 10g. Its just gravity
They do put significant stresses on the vehicle, but the point of maximum stress (max q) is at least 10km for most orbital rockets (Everest is 8.5km for scale). You aren't getting out of intense aerodynamic forces unless you build another Everest on top of Everest, and then another Everest on top of that, and then launch from that.
The conversation you jumped into is about the speed gained from the spin of the earth, which is directly correlated with radial distance from the Earth's axis of rotation.
Aerodynamic losses only accounts for a couple percent total of the delta-v budget. Even then, you don't even hit the peak aerodynamic forces (max q) until you're tens of kilometers above the launch altitude. This is because you're moving more slowly through the thicker atmosphere, so it doesn't have as much force.
Your in a really weird spot here where you are saying that all rocket engineers are wrong because you did the math on an idea that has been floating around pop science for years. Please go watch a livestream of a rocket launch. Watch how long it takes until it gets to about the height of a mountain. Then watch how much longer it takes before its done firing its engines.
Edit: also watch how quickly they turn sideways. By your thinking they should get out of the atmosphere before they turn.
I read a summary of a scott manley video, and he's an actual expert who I trust.
The raw delta v savings are marginal, the specific impulse improvement from optimizing the nozzle for lower pressure is marginal, and it looks like he doesn't even get into the high TWR builds that would take advantage of less drag to get higher speed faster...
Marginal improvements are a nice thing to have, when your up against the rocket equation
Yes but there are trade offs
1. Rocket launch sites are selected for being near the equator and with no population down range. This is already difficult and finding a mountain there is unlikely
2. Launch sites need lots of infrastructure. Building way up on a mountain requires building roads and utility lines up the mountain and all the materials to build a launch site. That is a significant additional cost.
3. People have to work at a launch site. The further from population centers you go the more you have to pay people to work there. If you go rally high up a mountain now you have to deal with altitude and weather events that happen up there.
All of this makes these marginal gains not worth it. His video is about why it isn't done anf is not a good idea. So maybe you should actually watch it.
I'm not wrong, what did I even say?
My actual position is that it's not worth it right now, but changes to infrastructure and TWR technology might make it more desirable in the future.
The rest is just .... I don't know what to call it while the mods are watching. The rocket science section of the didn't-get-the-joke club seems to be unsavory AF
Equatorial launches are cheaper, but not because it is easier to enter the orbit, but because it is easier to get to the desired orbit(inclination and parking orbit, this is from my memory of playing RP 1 in KSP, may not be correct)
Eh, you an orbit at any inclination you want and park in any orbit you want, but the reason the equator is useful is because you do get that added speed boost and most interesting things beyond earth are also on that plane (like the moon and geostationary orbital distances).
But there are tons of reasons to launch in more high inclination orbits too and a good chunk of satellites are launched in those orbits because they are better for earth observation (since you go around up and and down and the earth rotates under you, so every pass you get a different slice of land under you on the day side of the earth).
Wait so was it just because it's easier to plan inclination changes or was it something else. I remember reading something about rendezvous and orbital launching makes that easier?
It really has to do with human space flight more than anything and ground infrastructure. An orbit on a lower inclination is going to bring you over generally the same spot under you every orbit which is good for when you need to come home and for comms with the ground. The closer you get to the equator when launching the easier this is as it requires less of an inclination change (and also your ground infrastructure is going to be there, which is what you want the spacecraft to be going over).
We also get the added benefit that if you launch eastward you get a free boost in speed (this is why you rarely see launches that head west, even at places like Vandenberg, they usually go west only to dogleg north or south for whatever reason, and even then Vandy lets you go north and south pretty easily without having to make a dogleg), and also again, because things that we want to go to like GEO or the moon are also roughly on that same orbital plane.
There are also the logistical concerns as well as the desire to launch towards a large body of water in the east for detached rocket stages and malfunctions. This is why almost all rocket sites are by the ocean.
9.78 according to google. It also spat out a 7-10% increase in payload vs a florida launch which seems like a lot. Short term the logistics suck but thats an infrastructure problem that could be built out, bring the manufacturers to the best launch zone. Hardest part would be keeping the debris away from homes given you can't launch over an ocean as its land on all sides of the mountain.
To provide context, a cue ball seems really smooth right? The bump and pockets of a cue ball are much larger than Earth relative to its size. If you blew the cueball up to Earth's size, the mountains would be insane.
That's why, mountains are insignificant to space itself.
SpaceX is putting a launch site in South Louisiana for the same reason. There is also an advantage of movement of parts by water, from either the Mississippi, through the Panama Canal, or down the East Coast.
Pretty sure yall know our reputation for flatness and sea levels. Solid rock and high ground is pretty much non existent, in most of the state. Our only "mountain" is something like 300ft.
They’re putting it there for longer time over water when launching south for polar orbits. Also fuel is made there so less to pipe or ship. They’re planning on making starship there too so not so much for shipping.
I’d known about the time over water thing, considering Canaveral has always been our main launch site. I was very interested in the shuttle as an 80’s kid.
Ive been getting back into that interest, since buying Rocket Lab stock.
There was a local company that manufactured the “big gas tank” for the space shuttles, and there was a much larger ship building industry here in the past. I suppose that played into the decision.
If you could somehow spend fuel on the ground moving things to an optimal launch point to have to put less fuel in the rocket, it would absolutely be worth it.
Yeah, ultimately to get more effective rockets without just making "more rocket" requires a huge amount of ground infrastructure.
This is also the reason the European Space Agency primarily launches in... South America. Fresh Guiana to be exact, which is super close to the equator whereas Europe is not.
Seems like the easiest way to solve both the sideways velocity and the less fuel problem would be to use a giant maglev / gauss cannon track to get the rocket up to speed before activating the thrusters.
Hell, we could use a mountain to brace the track. What kind of speeds could we get up to with a maximum track height of Mount Whitney, or Guadalupe Peak?
In a fictional equation where the only thing you had to consider was the cost of transporting the rocket and fuel up the mountain, then it would probably be worth it.
But the reality is maintaining a launch complex is a major operation and requires hundreds of personnel and complicated infrastructure which needs to be maintained even between launches. The ongoing cost of doing this on a mountain outweighs the tiny benefit gained from the altitude.
On the other hand, the launch complex in Florida is easily accessible from several major cities, so while operating it is expensive, it’s not necessarily more expensive than operating it anywhere else.
In the pile of ideas about this, OP, daspowerhouse here has the basic explanation for you. "To get to orbit requires you to go very fast sideways" - Yes. Depending on orbit shape and altitude, in Low Earth Orbit (LEO) more than 90% of the energy is in velocity (kinetic) where less than 10% is due to altitude (geopotential). Most fuel is used to get orbital speed rather than to get altitude.
The rocket needs a huge amount of thrust and fuel to get out of Earth's gravity in the first place. That's where most of the combustion and fuel consumption happens.
In space, a spacecraft mostly coasts once it has enough velocity. The hard part is getting it there.
Air breathing space launch vehicles don’t really exist for launching any meaningful payload. Even at sea level, if you limit yourself to the fuel you can burn with an air-breathing engine, your thrust wouldn’t be enough to launch anything other than a microsat.
The Falcon 9, for example is roughly 2/3 liquid oxygen by volume. Having more oxygen means you can burn more fuel, and more fuel means more thrust. The same way super chargers and Nitrous deliver more oxygen to a car engine, allowing to to burn more fuel and have better performance.
9.6k
u/rysy0o0 4d ago
It would cost a lot of money to haul all the rocket parts and fuel on top of a mountain