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Questions tagged [mass-fraction]

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Conceptually, the lower the propellant mass fraction the better, right?

Rocket Propulsion Elements, 7th ed. Sutton, pg 30 states: "A high value of the propellant mass fraction is desirable." - I tend to disagree with this statement as described in that section because a ...
2
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1answer
179 views

Problem in finding Propellant Mass using Rocket equation where total mass includes components dependant on Propellant Mass

Formulation - $$e^{\Delta v/v_{exhaust}} - 1=mass_{fuel}/mass_{structure}$$ $\text{let } k=e^{\Delta v/v_{exhaust}} - 1 $ $$\implies mass_{fuel}= k \times mass_{structure} $$ According to SMAD (...
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0answers
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Understanding the multi-stage mass tables in Wiesel's Spaceflight Dynamics

In Wiesel's Spaceflight Dynamics, 3rd Edition (2010) Chapter 7.5 (pg 220), there is a table of mass values for Von Braun's 1951 design for a three-stage space station supply rocket. In the book, the ...
12
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1answer
400 views

Flying fuel tanks! Which deep-space spacecraft had the largest fuel mass fraction?

The Los Angeles Times' Deborah Netburn just wrote a really nice retrospective; ‘OK. Let’s do it!’ An oral history of how NASA’s Cassini mission to Saturn came to be with plenty of photos and quotes ...
5
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1answer
461 views

Why will SLS Block I bring less mass to LEO than the STS shuttle system did?

The Space Transportation System (STS) could bring a fully loaded shuttle orbiter of 109 tons to orbit (or maybe empty+payload 68+25=93 tons). The Space Launch System (SLS) Block I is based on STS, but ...
6
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2answers
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Fuel needed for rocket lift-off as a function of the altitude

Suppose I want to send a rocket to Mars, or to the Moon, from earth. How much fuel (in percentage of the full load) is needed for the rocket lift-off as a function of the altitude? I don't know if it ...
3
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2answers
456 views

How much fuel can Falcon 9's upper stage bring to orbit, without any other payload?

I wonder how useful SpaceX' second stage would be as a propulsion stage docking in LEO or so with separately launched payload. It seems to carry 92 tons of propellant on the launch pad. How much could ...
2
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5answers
361 views

Could fuel be “hosed” (pumped) from the ground to a launcher?

Most fuel on board a launcher is used during the first couple of minutes. Most of the propellant is needed to carry other propellant. For example, Saturn V (kerosene) and Delta IV (hydrogen) use about ...
1
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1answer
246 views

How does the mass of launchers change over time between ground and orbit?

I would like to see some comparison between different launchers wrt how quickly their mass is reduced over time (or altitude or velocity). There are differences in overall size class, propellant type, ...
5
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0answers
505 views

Falcon 9 v1.1 Full Thrust Specifications

Does anyone know what the dry mass and mass ratio of the Falcon 9v1.1 Full Thrust Stage 1 is? The best info I've been able to find was by taking the specified burn time and multiplying it by the mass ...
15
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3answers
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Is this a correct understanding of Tsiolkovsky's rocket equation?

When I graph the rocket equation, substituting arbitrary values for v(exhaust) and m1, so m0 because m1 - m0, the graph implies that increasing propellant mass past a certain point does not increase ...
13
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2answers
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How much mass could the Saturn V rockets have landed on the Moon if nothing was coming back?

What dry mass could have soft-landed on the Moon if a Saturn V had been reconfigured to launch a robotic mission going entirely to the surface? Obviously, that wasn't possible at the time, but for a ...
13
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4answers
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Why are rocket mass on the launch pad and payload mass to LEO not strongly correlated?

What explains the relation between how much a launcher weights on the launch pad, and how much mass it can lift to orbit? I had expected that more payload requires more fuel to be launched and that a ...
6
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3answers
2k views

How is “payload to LEO” estimated for a launcher?

Payload to LEO is commonly used as the bottom line of what a launcher can accomplish. But it must depend on factors which are not launcher specific, such as launch location and orbital characteristics....
5
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1answer
417 views

Why are pressure-stabilized rockets not more common?

The Atlas rockets and Centaur upper stages (often used in combination) successfully use(d) pressure-stabilized tanks to minimize dry mass. This technology was not used in any other rocket stages I'm ...
4
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1answer
622 views

Most energy efficient mass ratio of a rocket, or exhaust velocity

In the process of thinking about some hard science fiction, I need to substitute some mass fractions that will minimize the amount of energy used in order to be maximally generous to the author. So ...