# Launch altitude and fuel cost [duplicate]

In this question, higher altitude launches are discussed, but no one seems to address fuel consumption.

Let's take the Saturn V for example. A Saturn V rocket on the launch pad weighed approximately 3,350 tons. With the launch at sea level, it took about 39 seconds to reach 2200 m (the altitude of Santa Fe, New Mexico). At approximately 15 tons of fuel per second, the Saturn V consumes 585 tons of fuel (17.5% of its launchpad weight) just to get to an altitude that we can reach with a train.

There are other high altitude cities in the U.S., some of which are near the ocean (if that's needed). Even a not-so-high city like Salt Lake City, Utah saves the Saturn V 31 seconds of burn time and 465 tons of fuel.

I've heard arguments about transporting parts and fuel, but remember that a lot of these things were already shipped across the country just to put them in Florida.

So, from a weight and fuel consumption standpoint, why do we not attempt more high altitude launches?

• Before anyone points it out, yes I am aware that you don't save all of that fuel. At 2.2 km Apollo 11 had a velocity of 138 m/s, where a launch from Santa Fe obviously would start at 0 m/s. But still... you'd save a lot right? Feb 24, 2015 at 20:05
• Because you wouldn't save much fuel at all? Remember, getting into orbit is about achieving orbital speed (here's a calculation for ISS altitude), altitude is the easy part. And gravity a bit higher up isn't that much smaller either (calculation for 30 km above mean sea level). Feb 24, 2015 at 20:05
• High-altitude places are located in the middle of continents, and the rocket would overfly a lot of inhabited land on its way up. Feb 24, 2015 at 20:20
• @TildalWave That may be true, but I'd like to know more about this. How much of a factor is altitude? Obviously if you were starting 99 mi from the surface, the rocket would not need nearly so much fuel as most of the propulsion would be "sideways". Feb 24, 2015 at 20:22
• AlanSE's answer in the linked question actually does address fuel consumption, by way of delta-V; his "gravitational potential" term, saving ~300m/s with a Mount Everest launch versus a sea level launch, is what you're looking for. Feb 24, 2015 at 20:53