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45

It's even simpler than a German-American disagreement. It's use of ambiguous units. The term "specific X" means the amount of X you can get from a unit mass of something. For instance, in batteries, specific energy means the total amount of energy you can get from one unit mass of battery. As described in the Wikipedia article, *specific impulse" is the ...


11

It's the turbopump exhaust from the booster (jettisonable) engines. From Spacecraft and Boosters by Gatland p. 222-224 Exhaust stack discharges fuel-rich efflux outside reverse aerodynamic flow at base of missile In other words, the main purpose of the long duct is to get the fuel-rich turbopump exhaust away from the bottom of the vehicle to prevent ...


9

The J-2 was, to use a technical term "kind of throttleable". The engine incorporated a Propellant Utilization (PU) valve that could change the mixture ratio and thrust during operations. Picture from the J-2 Fact Sheet (really a whole, fabulous book). During engine operations propellant sensing devices in the vehicle propellant tanks control the ...


9

Your question is a bit confusing because of your use of "fuel" to sometimes mean "fuel" and sometimes mean "propellants". Based on my interpretation of the question here is an answer. The RD-170 consumes ~2400 kg/s of propellant. ~1800 kg/s of this propellant flows through the preburner of which ~33 kg/s is fuel (RP-1) and ~1767 kg/s is oxidizer (O2). The ...


8

Paraphrasing parts of an answer to a different question, hot-staging has a few advantages: It's less complex than staging using ullage motors since fewer parts are involved (whole rocket motors and their plumbing and tanks are missing, as well as the sensors and controllers to make them work correctly). Reduced complexity often means improved reliability. ...


6

Normally the tank is the wall is the structure. This minimizes weight. There are usually cylindrical regions connecting the different propellant tanks - sometimes called "intertanks". This portion of the structure does not contain propellant as the rest does. The shuttle external tank and the Saturn V are examples of that style; I do not know about Falcon ...


5

The difference in loading a flown booster and a brand new booster is the same. SpaceX starts loading RP1 and first stage LOX at T-35 min. RP1 fueling on the first stage finishes around the T-3 min and second stage around T-2 min time. For LOX fueling, they never really finish loading, they will keep topping off the LOX that's boiled off til about liftoff. So ...


4

Not a planetological exposition in sight so, I'll add my two cents to this rather theoretical discussion. Amongst exoplanetologists, the consensus has emerged that 1.6 Earth radii and 5 Earth masses is likely to be the upper limit to rocky planets¹. Simulations have shown that above these figures, the bodies develop increasingly Mini-Neptune² like ...


4

The term "specific" means "per unit." Specific impulse is defined as the impulse available per unit of fuel, and it has units of seconds when weight is chosen as the dividing unit. See this derivation by NASA for a step-by-step derivation of $I_{sp}$. I'll cover the important steps in this answer without relying on a unit system. We begin with the equation ...


2

There are three different devices being described here. The second two are closely related, while the first is different. The picture you have included is a device that functions first as a rocket until its solid rocket propellant is exhausted, and then reconfigures to use the rocket chamber as a ramjet chamber. It cannot operate as a ramjet before the ...


2

Earth Satellites: get TLEs from Celestrak or Space-Track and propagate them with SGP4. One way to do that and to also calculate their ground tracks (latitude and longitude) is the Python package Skyfield but there may be others. However I'm not aware of proper databases that you can download constantly updated positions already calculated each second. Things ...


2

A rotating detonation engine is at its heart a gas-turbine engine - i.e. it's meant for fuel to be mixed with air that you don't have to carry with you. Aerojet Rocketdyne has been testing them, but only mentions their application as a more efficient way to burn fuel--basically, the rotating shockwave helps to get complete combustion. But a rocket ...


1

Petroleum engineers design and develop methods for extracting oil and gas from deposits below the Earth’s surface source. The planet Earth is surely not the only celestial body that may have deposits below the surface that are worth extracting. I think it may be possible to find a research group or laboratory that would see such a project on topic. Probably ...


1

A "classical" fairing is a ballistic object, meaning it has no active controls. You'll find that trying to model its tumbling path through a highly variable atmosphere exceeds our current computational capacity. If you're thinking about the SpaceX fairing recovery techniques, be aware that there are some active controls, as explained in this space.SE ...


1

What are some of the known risks towards long term sustainability of manned space missions? What are the limited resources that could keep us sadly grounded? These days there aren't any special and essential resources for manufacturing spaceflight hardware that aren't also used more widely. Liquid fuels are produced or refined materials that are also ...


1

Your question is very broad, which is why it might be better suited to Worldbuilding.SE . There's a big difference between no longer being able to reach and operate an orbiting lab, and not being able to send humans to, e.g., Mars or the Kuiper Belt. For that matter, a nice global thermonuclear war would preclude sufficient resources to build a rocket....


1

You place it wherever you want. Unlike specific impulse, thrust is not an inherent property of a fuel. Every one of the entries in the second column refers to a specific engine design. If you need more thrust, you just make the engine bigger (or add more of them), keeping in mind that doing so will increase your vehicle's fuel requirements and overall ...


1

The way it was done in lost in space was pure science fiction as their engine technology is totally different, and that plot aspect was never really explained, so it's really a plot device (not that there's anything wrong with that, I'm not above doing it myself). In reality it is possible to create biofuel from waste, for example: Collecting Methane from ...


1

First, Season 1 of Lost In Space: In episode 9, the protagonists discover that their spaceship can be fueled with "petrified biomass" which has built up over hundreds of years in the cave. If I remember correctly, there was also some 'secret ingredient' that made this specific bat guano from that specific cave have the right minerals or chemicals in it or ...


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