I was watching a video of a Saturn 5 Rocket launch and I was amazed at how much fuel was used and how massive the explosion at the beginning was (and how massive the continuous fuel burn was).
But it got me thinking can we, in the future, develop rockets which can lift more payload per gallon of fuel or are all of our rockets equally efficient in terms of the rocketry version of “Miles per Gallon” because of some law of physics which we already mastered?
And I know there are alternatives like Space Elevators, but I’m specifically curious about rockets.
In: 6
As other commenters have said for a normal rocket engine the efficiency is measured in “specific impulse”. I found [this link](https://thephysicsofspacex.files.wordpress.com/2016/07/isp-upper-limits.pdf) which gives the theoretical upper limit of specific impulse for some common rocket propellants.
Since you asked about the Saturn V rocket specifically, it used kerosine/oxygen for the first stage and hydrogen/oxygen for the other stages. For kerosine/oxygen the theoretical maximum would be around 470s whereas the F-1 engines on the Saturn V only achieved 260s at sea-level, so only 55% efficiency. The second and third stage used the hydrogen/oxygen J-2 engine which has a specific impulse of 420s vacuum, which is already about 80% efficiency compared to the theoretical maximum of about 530s.
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