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Questions tagged [combustion]

The burning process, especially of propellants, or as it otherwise relates to spacecraft or missions in space.

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36 votes
9 answers
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Why do rocket nozzles flare?

Why do rocket nozzles open wider at the end than, let's say, get narrower? Let me explain: A jet engine works by having this amazing thing called a combustion chamber. The combustion chamber ignites ...
Frank's user avatar
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17 votes
2 answers
4k views

How exactly is the pressure inside the combustion chamber monitored?

Given that temperatures in the combustion chamber are crazy high, are there any pressure sensors rated for the high temperature and high pressures located there? Or is there a cooling mechanism for ...
Vasanth C's user avatar
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17 votes
1 answer
8k views

What are the advantages of Ox-rich staged combustion?

In the context of staged combustion, I understand that burning ox-rich creates complications associated with having hot, high pressure, oxidizer. Some engines, notably the RD-170 and RD-180 family run ...
randomUsername's user avatar
16 votes
4 answers
3k views

Are there any known atmospheres that would support traditional combustion engines?

If we landed a traditional automobile on the moon, the combustion engine would lack oxygen, and, for obvious reasons, would not function. I'm wondering if a planet terrestrial body exists where we ...
Magic Octopus Urn's user avatar
16 votes
2 answers
2k views

How do you confirm ignition in the combustion chamber of a rocket?

Is ignition confirmed using a temperature sensor, pressure sensor or another device?
Edward Jane's user avatar
13 votes
2 answers
4k views

Could a deadly fire start within a spacesuit?

At the end of S02E08 of the TV show "For All Mankind", a cosmonaut is shot on the moon and a fire erupts within his suit. My understanding is that the pressure of pure oxygen within a ...
phil1008's user avatar
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13 votes
4 answers
16k views

Why don't rockets drive the turbopump from the combustion chamber?

As I understand it, liquid-fueled rockets typically burn some amount of their fuel in a separate low-pressure combustion chamber, and then use the combustion products produced to drive the turbopump. ...
Witnaaay's user avatar
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10 votes
1 answer
1k views

How is blow-back prevented in monopropellant chemical rockets?

Let's say we have a monopropellant, pressure-fed rocket engine. We don't want the combustion in the chamber to propagate back up the fuel line and into the fuel tank or we will have a big kaboom. (...
DrZ214's user avatar
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8 votes
2 answers
1k views

Do any rocket engines besides the F1 need/require baffles?

The F1 engine required baffles on the injector plate to control combustion instabilities so that it wouldn't blow itself up. Was that unique? Or do other engines also have baffles for the same reason? ...
Greg's user avatar
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8 votes
1 answer
453 views

Has methylsilane (CH₆Si) ever been considered as fuel in rocketry?

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, -2612 KJ/mol or 56.8 MJ/kg (better ...
WOW 6EQUJ5's user avatar
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7 votes
2 answers
280 views

How do you calculate what percent of hydrogen combustion is turned into heat vs pressure?

As a high school calculus and physics student interested in aerospace engineering, I was trying to understand the basics of how a rocket works and couldn’t find an equation or any analysis online on ...
Mason Quinn's user avatar
7 votes
0 answers
255 views

Tory Bruno mentioned "unsolvable combustion instability" of "large methane engines". What, why, how?

Relevant tweet, an hour ago: https://twitter.com/torybruno/status/1405210138189864960?s=19 a Tweeted Question: Why wasn't methane used in the 2000s, when it was readily available unlike the time ...
Anton Hengst's user avatar
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6 votes
1 answer
12k views

Can I make my own RP1? [closed]

Is it possible for me to buy kerosene from a local store and then try to refine it to the extent where it would be considered RP1. If so how would I do it? For those who are wondering me and a group ...
jack's user avatar
  • 167
5 votes
1 answer
520 views

Does peroxide spontaneously decompose when introduced into hot combustion chambers?

I understand that hydrogen peroxide (HTP) can be decomposed into superheated steam and oxygen using a catalyst, but I haven't been able to find any information on whether or not it will decompose in ...
R. Hall's user avatar
  • 822
5 votes
1 answer
611 views

Detonation Liquid rocket engine

What is the detonation liquid rocket engine (LRE)? How does this work? How is it better than the average rocket engine? Russian scientists have successfully tested the first detonation liquid ...
Isrorian's user avatar
  • 569
5 votes
1 answer
179 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 ...
Roger Wood's user avatar
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5 votes
5 answers
785 views

What would adding 15% nitrogen do to pure oxygen as an oxidizer?

I'm working through Sutton's "Rocket Propulsion Elements," (8th Ed.) and it is mostly gibberish. However, I understand a little bit. Anyways, the question is: When using RP-1 as a fuel, your oxidizer ...
Tawooh's user avatar
  • 208
5 votes
1 answer
166 views

How does a liquid rocket engine prevent the combustion from going back in? [duplicate]

To my knowledge, the liquid engines usually utilize a turbopump to gush fuel into the combustion chamber. Later that fuel is mixed and injected in a mist form through the injector to be ignited. ...
Aerospace_Nerd's user avatar
5 votes
1 answer
221 views

How is pressure distributed in the combustion chamber of a rocket engine?

How, if at all, does the pressure of the combusting fluid change within a combustion chamber from the injector to the choke? Is it monotonically decreasing in pressure as you go from the injector to ...
Anton Hengst's user avatar
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5 votes
1 answer
5k views

How are the combustion chamber length and diameter decided

How are the combustion chamber length and diameter decided? Are there any proper formulations or procedures?
Amar's user avatar
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5 votes
1 answer
213 views

Does injection provide any significant thrust?

In all liquid rockets, you've got to inject the fuel into the combustion chamber at a higher pressure than the combustion chamber itself. This is why turbopumps may be used--to raise the pressure ...
Anton Hengst's user avatar
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5 votes
0 answers
217 views

What is the droplet size that is desirable for pintle injectors?

The pintle injectors tend to generate droplets after impingement of the fuel and the oxidiser stream and I understand that the droplets will be premixed. In such a case, even a larger premixed ...
karthikeyan's user avatar
  • 4,479
4 votes
2 answers
1k views

Platinum Colloid in Liquid Hydrogen fuel to increase fuel efficiency

In certain chemical reactions, catalysts can be used to decrease the activation energy of those reactions. For example, platinum is a catalyst for hydrogen/oxygen reactions, so, therefore, the ...
Boris Deletic's user avatar
4 votes
3 answers
448 views

How much of the exhaust speed is due to combustion and how much is due to the injection?

The thrust $F$ of a rocket engine is given by $$F=\dot{m}v$$ where $\dot{m}$ is the mass flow and $v$ is the exhaust speed. Now the first factor, $\dot{m}$, is almost entirely due to the turbo pumps (...
Everyday Astronaut's user avatar
4 votes
1 answer
409 views

How are rocket propellants ignited repeatedly without the ignition source melting

I know that SpaceX's Falcon uses TEA-TEB instead of a physical igniter, but if I remember correctly, NASA has never used hypergolic propellants to start their restart-able engines. How does NASA's (or ...
user22624's user avatar
4 votes
1 answer
897 views

Cooling a hydrolox rocket with Water

Would it be efficient to use water as a coolant in a hydrolox rocket, then feed the steam after the water has boiled (due to heat transfer from the engine nozzle) into the combustion chamber, so as to ...
C. Bird's user avatar
  • 43
4 votes
1 answer
197 views

Is there a relation between combustion instabilities and chamber pressure?

Is there a relation between the combustion chamber pressure, and either an increase or decrease in both high and/or low frequency combustion instabilities. If so, how has this influenced engine design,...
R. Hall's user avatar
  • 822
4 votes
1 answer
249 views

Discrepancy in local Mach behavior between CEA and other sources

I'm exploring some designs using the NASA CEA (Chemical Equilibrium with Applications) code and I ran into a discrepancy between CEA predicted values for local Mach number at the exit plane and values ...
ecfedele's user avatar
  • 527
4 votes
1 answer
610 views

Don't Preburner exhaust fumes disturb the combustion in a Full-flow Staged Engine?

Since Full-Flow Staged Engine uses preburned fuel/OX-rich gases in combustion chamber, don't those exhaust fumes produced by the preburner somehow unbalance or 'pollute' the pure combustion of fuel ...
Spacha's user avatar
  • 168
3 votes
2 answers
346 views

Is presssuized gas absent in a turbopump-driven rocket engines?

For RL-10 rocket engines, are the propellent pumps able to provide the propellent without a source of pressurant gas?
user28833's user avatar
  • 499
3 votes
1 answer
162 views

Other than rockets, have internal combustion engines run in space?

According to https://en.wikipedia.org/wiki/Advanced_Cryogenic_Evolved_Stage The Advanced Cryogenic Evolved Stage (ACES) .. proposed (using) a lightweight internal combustion engine to use hydrogen ...
Woody's user avatar
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3 votes
2 answers
1k views

What are the choice of materials for LOx pumps casing and impellers?

Given the highly corrosive nature of LOx and the extremely low temperature, what materials are usually used for the LOx pumps? Steel, Copper, and many alloy tend to be flammable in liquid Oxygen ...
karthikeyan's user avatar
  • 4,479
3 votes
1 answer
462 views

I don't know where to start with the calculations - rocket engine

Last year I stumbled upon the "How to design, build and test a rocket engine" pdf and since then I have been intrigued by making one (or at least calculating it). So I've been doing some ...
StarshipGood's user avatar
3 votes
1 answer
242 views

What would happen if we ignited one of the gas giants? [closed]

Since we have the technology to launch an enormous explosive into the atmospheres of the gas giants, would it be possible to light one on fire since their atmospheres are pretty much all just hydrogen ...
Josh Withee's user avatar
3 votes
1 answer
996 views

How long does Augmented Spark Igniter fire?

The heroicrelics.org page J-2 Rocket Engine Augmented Spark Igniter mentions that The ASI operates continuously during entire engine firing Does this how all spark igniters function in rocket ...
karthikeyan's user avatar
  • 4,479
3 votes
1 answer
487 views

Which are more efficient: oxidizer-rich or fuel rich rocket engines?

Several internet articles claim that the high Isp of the Soviet RD-180 engine (as used in the Atlas III and V launch vehicles) was (at least partially) due to the fact the RD-180 ran oxidizer-rich, ...
Woody's user avatar
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3 votes
0 answers
143 views

Atlas V RD-180 Analysis

I was tasked with researching certain properties of the RD-180 engine. I am finding contradictory information, or I am unable to find it at all. I am looking for the following information Mixture ...
PilotGeometer's user avatar
3 votes
0 answers
209 views

What is the cause of soot in the plume of the Raptor engine?

Though the Raptor engine burns quite clean, it was clear from some early test flights that it did produce some visible soot: There have been differing explanations for the exact cause of/source of ...
quinnkenri's user avatar
  • 1,130
3 votes
0 answers
142 views

Closed oxygen cycle methane-burning internal combustion engine for Titan rover/helicopter? Works like a battery together with RTG that won't freeze?

@TildalWave's answer to Methane internal combustion engines for rovers on Mars and Moon. Feasibility? raises the possibility of using Titan's atmospheric methane for an energy source as long as you ...
uhoh's user avatar
  • 149k
3 votes
0 answers
58 views

Where could I find more propellant combustion charts for more different/more broad examples/numbers?

So after asking how I could calculate this kind of propellant combustion charts for different fuels/oxidizers and other ratios and other stuff and getting some really good answers, especially from ...
StarshipGood's user avatar
2 votes
2 answers
733 views

Could chemical energy quicken ion propulsion?

Background Tsiolkovski's rocket equation says that change of speed is proportional to the exhaust velocity. Chemical propulsion seems to have a strictly limited and since long achieved maximum ...
LocalFluff's user avatar
2 votes
1 answer
322 views

What happens when LOX and H2 are injected into the combustion chamber of a rocket?

I can't seem to find an answer on this. I thought that when oxygen and hydrogen get injected they collide and break bonds etc. to form water vapour which because of the pressure in the combustion ...
Krem's user avatar
  • 21
2 votes
1 answer
408 views

What is the effect of poorly choosing L* in combustion chamber design?

I am a member of a university rocketry club and we are in the process of designing a liquid rocket engine. One of the previous propulsion leads did the primary conceptual design of this engine in RPA. ...
landobean's user avatar
  • 151
2 votes
1 answer
1k views

Why spray LOx into combustion chamber, if GOx is more effective?

Are there any issues in transforming the liquid oxygen into gaseous oxygen before injecting into the combustion chamber? Gaseous Oxygen will be readily available for combustion and will mix well with ...
karthikeyan's user avatar
  • 4,479
2 votes
1 answer
194 views

combustion chamber evolution

Comparing photos of combustion chamber designs from the the 1940's and 1950's to those of today, it looks to the amateur observer such as myself that the size of the chamber proper, where fuel and ...
jpfop's user avatar
  • 341
2 votes
1 answer
278 views

For F1 rocket engine, why propellant holes were not in proportion to the fuel to oxidizer ratio?

I understand that the F1 rocket engine had (approximately) 1428 Oxidizer holes and (approximately) 1404 Fuel (RP1) holes in the injector plate. Since the Oxidizer to fuel ratio was 2.27:1 for the F1 ...
Niranjan's user avatar
  • 3,796
2 votes
1 answer
161 views

How heavy can a fuel tank get before making it heavier is a liability under any circumstances?

This Question may bend the boundaries of this community a little, since it's mostly about hypothetical rockets that would never be built. Considering a filled fuel tank has to withstand a lot of ...
justthisonequestion's user avatar
2 votes
1 answer
348 views

What proportion of a rockets fuel remains unburnt?

Presumably liquid rocket combustion is never 100% efficient, so what proportion of fuel does typically remain unburnt, venting into the atmosphere, and does this vary for different rocket designs and ...
Dent Arthur Dent's user avatar
2 votes
2 answers
284 views

Do full flow rocket engines still use injectors? If so, how? How exactly are the oxidizer and fuel sent into the combustion chamber?

I'm learning about rocket engines and full flow engines, and I'm a little confused about what goes on in the combustion chamber. It was my understanding that injectors were pretty much necessary to ...
Aferb's user avatar
  • 21
2 votes
0 answers
55 views

What impact do inhibitants have on H2O2 performance?

How do the combustion characteristics, as well as the speed of decomposition, of inhibited hydrogen peroxide differ from those for pure H2O2. If a smoother combustion is achieved with pure hydrogen ...
R. Hall's user avatar
  • 822