Questions tagged [liquid-fuel]

Questions regarding rocket propellant in liquid form, the main type used for chemical rockets.

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6
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1answer
67 views

Does anyone know the stay time, or what characteristic length should be used, for a LOX/LCH4-fuelled rocket engine?

Just what it says on the tin. I need to know either the "stay time" (Ts) or characteristic length (L*) that would be used to figure combustion chamber dimensions used with a LOX/LCH4-...
12
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1answer
3k views

Why can solid rockets be both the skinniest and most spherical launch vehicles while liquid fuel rockets have a more limited range of aspect ratios?

Question: Why can solid rockets be both the skinniest and most spherical launch vehicles while liquid fuel rockets have a more limited range of aspect ratios? Are there fundamental engineering ...
1
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1answer
128 views

Comparison of rocket engines using LH2 & LOX as propellants

I am a bit confused - If it is correct that RL 10 and LR 87-LH2 both were developed in 1950 by Aerojet, and both used LOX and LH2 as the propellants, if so, then why was there a huge difference in ...
2
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1answer
120 views

What expansion ratio is the best for mars surface level engines?

What expansion ratio is the best for mars surface level engines? For launches from Earth, first stage nozzles are much shorter than second stage nozzles because of Earth's high sea-level pressure. For ...
4
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1answer
122 views

Can rocket engines which use hypergolic propellants be augmented with LOX for increased efficiency?

Hypergolic rocket engines typically use NTO and hydrazine based propellants. Wikipedia page on Liquid Rocket Propellants shows N2O4 and N2H4 at 1.36 ratio to have 286s Isp at sea level. My question is ...
3
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1answer
116 views

Was liquid ozone + fluorine ever tested as an oxidizer? Ever with jet fuel?

Searching for ozone layer circa 1957 I got Theoretical Rocket Performance of JP-4 Fuel with Mixtures of Liquid Ozone and Fluorine, NACA RM E56K14, Issue 58, Volume 63, Vearl N. Huff, Sanford Gordon. ...
4
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1answer
68 views

Can kerolox or SRB soot particles grow too large too quickly; not accelerated in expanding exhaust leading to a loss of mass-specific impulse?

In this answer to Is methyl silane CH6Si ever considered as fuel in rocketry? I argue that there's no huge loss in mass-specific impulse (Isp) when producing sand (and by extension soot) in the ...
12
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1answer
3k views

Why is an inflatable balloon inside a fuel tank not used to prevent fuel from “sloshing around”?

After seeing all the Starship failures, having something with a membrane keep things in place seems like an obvious solution. Has it been considered or tested - or do we simply lack a material that is ...
4
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1answer
157 views

Why are propellant tanks filled from the bottom?

It seems that the norm is to (fast-) fill fuel and oxidiser tanks from the bottom. For example, on this drawing of the Saturn S-IC stage you can see the LOX and RP-1 fill valves at the bottom of the ...
3
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0answers
68 views

Injector design - LOX vs nitrous oxide

What will be the main design differences between using liquid oxygen and liquid nitrous oxide as oxidizer in a bi-propellant rocket engine? What liquid/gas properties (vapor pressure etc.) play the ...
3
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1answer
266 views

Open source liquid rocket engine

Is there an open source bi-propelant liquid rocket engine that would have all the documentation, computations, test results and 3D design files (CAD) freely accessible?
0
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1answer
74 views

Highest Isp achieved with nitrous oxide as oxidizer

What is the highest Isp achieved on orbital rocket for an engine that used nitrous oxide as oxidizer? Both hybrid and liquid engines can be considered. Not considering nitrous oxide monopropellant ...
4
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1answer
207 views

If high-test peroxide is most stable when pure, why are most uses of it in rocketry at lower concentrations?

Per the Wikipedia article for High-test peroxide: Hydrogen peroxide becomes more stable with higher peroxide content. For example, 98% hydrogen peroxide is more stable than 70% hydrogen peroxide. ...
2
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2answers
132 views

Is there a “green” hypergolic propellant?

Is there any such thing as a non-cryogenic, liquid, "green" hypergolic bipropellant, where green means environment friendly and non-toxic?
3
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1answer
85 views

What is the products of a catalyzed reaction between Hydrogen Peroxide and Ethanolamine with Copper(II) Chloride?

I found this article about Hypergols, specifically H2O2. It mentions in table 3 and in the body of the paper that they found that Ethanolamine with Copper Chloride reacted vigorously. In my search for ...
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102 views

Liquid fueled suborbital rockets?

Which suborbital (sounding, balistic, amateur or else) rockets use or used liquid fuel? I could find (with help from A. Rumlin) New Shepard - Blue Origin - RP-1 Spica - Copenhagen Suborbitals - ...
4
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2answers
3k views

Rocket fuel cost to launch 1 kg to orbit

I have 2 questions about the cost of liquid rocket fuel to launch (anything) to LEO orbit. Let's assume we use fuels used in commercial spaceflight today (probably LOX+LH2 or LOX+RP-1 etc.). What is ...
5
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1answer
92 views

Is there a distinct flame-front in a liquid-fuelled rocket combustion chamber?

Liquid fuel and liquid oxidizer are injected at high pressure through small orifices into the 'top' of a rocket's combustion chamber. The intention is that these mix quickly and then burn completely ...
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2answers
86 views

How many times is a single rocket engine tested?

When a rocket engine is loaded into a test stand is it tested once before removal or is it allowed to cool and then tested again. Is every liquid-fueled rocket motor that flies to space first tested ...
2
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3answers
242 views

Can liquid rocket engines have the same thrust as solid rocket engines?

Take the Vega rocket launcher for example. Its first three stages are solid rocket engines and burn at a relatively short time. If I were to change its first stage into a liquid rocket engine, can ...
1
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1answer
56 views

What is the effect of calorific value of fuel on the specific impulse of a rocket engine?

What is the effect of calorific value of a fuel on the specific impulse of a rocket engine? Other things remaining the same, and if it is possible to use both, will the same fuel provide the same ...
3
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0answers
94 views

Dinitrogen tetroxide decomposes to nitrogen dioxide at room temperature, but rockets that use it are usually said to use N2O4 and not NO2 - why?

To the best of my understanding, both dinitrogen tetroxide and nitrogen dioxide are usable and perform quite similarly as oxidizers, but rockets that use either are almost always said to use ...
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5answers
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Using of the rocket propellant for engine cooling

Why does liquid space propellant make a good engine coolant? I was researching the regeneratively cooled nozzle and combustion chamber on the Merlin 1D when I found this out. I do know that the pipes ...
4
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0answers
149 views

Why didn't propylene fly? (Vector—yes, Vector—is back)?

Ars Technicha's Rocket Report: SLS has technical problems, Vector—yes, Vector—is back links to Vector restarting operations under new ownership which says: One thing they did wrong was the technology ...
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1answer
105 views

Concerns/challenges with LOX as a regenerative coolant

What are the fundamental issues that make LOX as a regenerative coolant difficult to work with or less ideal than using fuels as a coolant instead in small scale engines (<7000lbs of thrust/ ...
4
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1answer
88 views

How to experimentally determine the degree of atomization of the propellants mixing in a fuel injector?

When validating a fuel injector design on a test stand using liquid water to simulate a liquid-liquid fuel injector(the one i'm working with currently is a pintle design but I suppose one could ...
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4answers
3k views

Do the SpaceX Falcon-9 rockets use foam insulation similar to the Space Shuttle? Is it still a potential problem?

The Space Shuttle used polyurethane and polyisocyanurate foams for insulation. A chunk of foam breaking off during launch resulted in the Space Shuttle Columbia disaster. Do all chemically-fueled ...
3
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1answer
101 views

At which pressure does a liquid fueled rocket start producing supersonic flow?

In a compressed-tank LOX+ethanol (or similar liquid fuel) rocket: How much should the tank or combustion chamber pressure (which should be the same) be to have a significant exhaust velocity increase ...
3
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0answers
830 views

How do Falcon-9's cold gas thruster maneuvers account for the center of mass changes due to “floating fuel shifts”?

The Art of Engineering video How SpaceX Lands Rockets with Astonishing Accuracy after 07:19 explains: Cold Gas Thrusters The falcon 9 is equipped with a total of ...
5
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1answer
408 views

How much does launch costs have to come down to make chemical fuel deep space probes feasible?

Considering that NASA have been running short of plutonium for their RTGs, it makes sense to consider alternatives. For the inner solar system up to Jupiter, solar cells have been demonstrated on ...
3
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1answer
55 views

How to predict reaction of propellants at chamber temperature and pressure? [duplicate]

I would like to understand how to calculate the complete reaction of propellants at chamber temperature and pressure. For instance taking ethyl alcohol (75%) and LOX combustion with mixture ratio of 1....
10
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1answer
627 views

why do under-expanded engines have less than ideal thrust?

I've been looking into rocket propulsion a bit and got stumped on something. I read that the thrust generated by an engine can be determined by the following: $$ F = \frac{w}{g}v_{e}+A_{e}(P_{e}-P_{a})...
8
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1answer
213 views

Is methylsilane CH6Si ever considered as fuel in rocketary?

Methylsilane CH6Si seems to have some useful properties for rocket fuel: High hydrogen content, 6 atoms per molecule, 13% of overall mass, High combustion energy, -2612KJ/mol or 56.8 MJ/kg (better ...
10
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4answers
4k views

Why can't cryogenic oxygen and cryogenic kerosene be “stored” together?

This question, to my knowledge, is only applicable to Rocket Lab's Electron, pressure-fed engines that use non-hypergolic fuels, and other engine cycles that don't use a fuel/oxygen-rich preburner. My ...
7
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1answer
665 views

Why is RP-1 dyed red?

I was interested to learn that RP-1 is at least sometimes dyed to a red color. What is the reason for doing this / what benefit does it give compared to leaving it the usual hydrocarbon clear-to-...
2
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1answer
249 views

Fat as hydrocarbon rocket fuel?

Have fat/grease or fatty acids ever been studied as a liquid rocket fuel? (I don't expect it to be a good rocket fuel, but I wonder if anybody has ever burned it in an engine or made a serious study ...
18
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1answer
624 views

What is the MXP-351 storable bipropellant?

Masten Space Systems has a proprietary hypergolic bipropellant called MXP-351 intended for use in the XL-1 lunar lander. We seem to know the following information: Non-cryogenic, with storage life of ...
24
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1answer
3k views

What actually is RP-1, and how is it different from any other hydrocarbon liquid fuel?

Related: Russian "kerosene" versus American "RP-1", however that's more about the details of specific rocket kerosene specs than rocket kerosene in the context of hydrocarbon and ...
7
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1answer
422 views

Do mixture ratio always need to be constant throughout the flight?

What factors can change the mixture ratio of propellant? I think they can be changed to control the thrust of a rocket.Stay safe. EDIT:What about considering only one stage? Do they change or can they ...
3
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0answers
105 views

How are cryogenic fuels and oxidizers generated and procured?

I understand hydrogen can be generated from steam-methane reforming or from electrolysis of water and then cooled to liquid through a series of cryogenic coolers. For steam reforming, the hydrogen ...
10
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1answer
658 views

How are fuel/hydraulics pipes coupled in spacecraft?

How are pipes coupled in spacecraft? I found Shape memory alloy pipe couplings (SCoup, see image taken from link) are sometimes used. -Is this still the case and in what quantity are they used? -...
4
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2answers
225 views

Bio-Fuel for Rocket Science

In season 1 of the 2018 Lost In Space Series which aired on Netflix† the last Episode has the Robinson family using the by-products of living beings (faeces) as biofuel. If we were to use the same ...
3
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1answer
362 views

How did JPL detonate a liquid oxygen methane mixture with light?

This answer to Pre-mixing cryogenic fuels and using only one fuel tank quotes John D. Clark's Ignition! Chapter 11: The Hopeful Monoprops, and the quote includes the line: How he avoided ...
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1answer
1k views

What is the density of supercooled LOX at −206 °C, as SpaceX uses it

I want to calculate the size in cubic meters of Starship's propellant tanks. The only figures for LOX I can find are at −183 °C. 1141.7 kg/m³ at −183 °C. Could somebody please calculate it at −206 °C,...
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6answers
4k views

Is it possible to use gases instead of liquids as fuel in a rocket engine?

Im reading about rocket engines and I have a question about is it possible to use fuels in the form of gases than a liquid in a rocket engine?
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3answers
1k views

Rocket explosion compared to kT of TNT; has one ever knocked something over at a distance?

The energy equivalent of 1 gram of TNT is about 1 kcal or large Calorie. For reference, 1 gram of carbohydrates gives us almost 4 Calories of energy (if we are lucky enough to use it and not store it)....
3
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1answer
300 views

Why did Virgin Galactic decide to use a hybrid engine vs liquid on their space ship?

To me, it seems like their business case is very dependent on rapid reuse. With this in mind, using a hybrid engine that would need to be replaced every flight seems very counter intuitive vs a liquid ...
4
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0answers
168 views

Are there examples of a spacecraft designed for transitions from supercritical to liquid+gas mixtures?

The question What happens when supercritical fuel tanks deplete below critical point? suggests some possible scenarios when the pressure of a tank is in danger of dropping below the supercritical ...
3
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1answer
344 views

What's the viscosity of chilled RP-1?

I would like to compare the viscosity of "chilled" RP-1 as it is used for Falcon 9 launches to that of some everyday fluids. However, I am unable to find this information elsewhere. Would you please ...
21
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2answers
2k views

Do liquid propellant rocket engines experience thrust oscillation?

I know SRBs have a quite bit of thrust oscillation, and it's pretty much part and parcel of burning solid propellant. Do liquid-propellant engines experience something similar albeit at a much smaller ...