New answers tagged fuel
0
Apart from such issues, would such a propellant offer any benefits such as a high ISP, for example?
There's one and only one property that makes zinc to occasionally show up in NTR contexts.
Density
Everything else about zinc as a propellant is terrible.
The ISP is very bad. Handling what's under normal conditions a solid is bad.
But the density is a nice 7....
answered 6 hours ago
SE - stop firing the good guys
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4
Zinc has too high molar mass to find any practical application in Nuclear Thermal Rockets (NTR) as propellant fluid. An additional limitation in solid core NTR is the difficulty of achieving propellant temperatures higher than 2700°C because there are no such materials that have satisfactory mechanical properties at higher temperatures. Zinc has a relatively ...
3
If a rocket using cryogenic fuel and oxidizer is launched from a blimp, no fuel will be saved.
During the blimp flight from ground to launch height, the rocket will loose a lot of fuel by evaporation.
A rocket to reach an orbit at 400 km height and 8 km/s speed saves only very, very little fuel when launched from about 10 km height provided by a blimb.
So ...
4
In addition to the factors already mentioned: The Falcon operates in a very different economic model than anything that has come before.
Look at the electronics industry for a comparison, specifically the term "bleeding edge". You pay through the nose for the best performance. SpaceX took this lesson to heart in the design of the Falcon--they ...
4
Because in 2002 there were no existing methane engines they could use or copy (at least none suitable for a booster).
SpaceX didn't have the time or money to develop a whole new engine using a whole new fuel from the ground up. Instead, they based the Merlin 1-A off of NASA's existing Fastrac design, which was a kerolox gas generator.
Initial raptor ...
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The first methalox engine I've been able to find, the RS-18, was developed two years after the first flight of Falcon 1 and the Merlin engine. In contrast, RP-1 had a half-century of development history behind it, and hundreds of engine designs that used it.
SpaceX is, first and foremost, a business. Going with a proven technology for your first product is ...
20
SpaceX chose to use RP-1 because the development path for a good RP1 engine was a full decade shorter! Plus many other factors favoring KeroLox for launch from Earth surface, for example the very high energy density of RP-1 allows smaller tankage, which is a great advantage when flying through the atmosphere. The Excellent thrust density of RP-1 also allows ...
3
How much fuel would it take? And how large should be a booster / rocket ?
That depends on the engine and propellant. Tsiolovksy rocket equation is
$$\Delta V = \ln\frac{m_i}{m_f}I_{sp}g$$
where
$\Delta V$ is change in velocity (in this case, 11000 $\frac{m}{s}$)
$m_i$ is the initial mass before the burn (payload plus propellant plus dry mass for the ...
4
There are two figures which matter here: one is the energy that ends up in the thing you are accelerating. This is just given by
$$\frac{m_P \Delta v^2}{2}$$
Where $m_P$ is the mass of the thing, and $\Delta v$ is the change in velocity (I am tacitly assuming that this kinetic energy is relative to someone for whom the object is initially at rest).
The ...
2
Kinetic energy is $\frac {1}{2}mV^2$ so you're looking at $55$ GigaJoules of energy. That's enough to power ~86 U.S. homes for a year according to this U.S. EIA FAQ
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When we talk about the combustion of elements in pure oxygen, per overall reactant mass, silicon is in the fifth place when comparing the highest oxidation states. Seen in descending order (Be>Li>B>Al>Si). Beryllium is very toxic and expensive and has potential application only in space, Lithium is a very reactive element with low density. Boron ...
1
Silicon atomic weight is 28, vs 12 for Carbon. The energy of the silane Si-H bond is 318, vs 412 for C-H (and 432 for H-H).
So probably not for rockets, maybe yes for a "green fuel" that leaves sand rather than CO2 as a waste product. (fine silicates do have issues as lung irritants).
Polyvalent metals, such as finely ground aluminum, do find use ...
6
I was a missile tech on a SSBN in the '70s and worked on the Poseidon C3 SLBM. This missile had six "Thrust Termination Ports" arranged around the periphery of the second stage motor dome. Each TTP was a 10" diameter fiberglass tube angled outward from the motor dome to the side of the missile with det-cord at each end.
When commanded by the ...
1
Okay, so my previous approach didn't work out. So let's try another.
Hydrogen need not have any more ISP than reinforced concrete. Indeed, there's little difference between the two if you are simply throwing hydrogen canisters out of the nozzle to get thrust. That is, if you are accelerating the reaction mass that is stationary macroscopically and ...
21
They do!
Many propellant tank, especially those required to work in zero-g environments, do use just such a bladder-inside-a-tank for the fuel. Typically monopropellants for thrusters.
It completely removes the requirement for Ullage of the propellants, but adds complexity, cost, mass and failure modes.
Additionally, flexible bags are a bit hard to make at ...
3
Why lighter atoms work better as fuel for a rocket:
The simple explanation, with concept only no numbers.
A rocket takes an amount of energy, puts that energy into matter, and that causes the matter to be shoved out the rear of the rocket, producing thrust.
(The energy usually comes from chemical reactions, thus heat. But it could also be pure thermal, or ...
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Thrust termination is the goal of Range Safety in the event of an errant rocket. Rendering the boosters inert is considered secondary, when possible.
The Range Safety Officers don't rely on the current positions of the vehicle to decide to terminate, but instead are looking at the IIP (Integrated Impact Point) on a map. The IIP is the point where the ...
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Well, I can refer you to the Range Safety Wikipedia entry:
Two switches were used, ARM and DESTRUCT. The ARM switch shut down
propulsion for liquid propelled vehicles, and the DESTRUCT ignited the
primacord surrounding the fuel tanks. In the case of manned flight,
the vehicle would be allowed to fly to apogee before the DESTRUCT was
transmitted. This would ...
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