Questions tagged [combustion]

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

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1answer
136 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 ...
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2answers
199 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? ...
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3answers
227 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 (...
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1answer
91 views

Conditions on Titan under which human breath can be set to fire

Motivated by the question Titan vs Mars for colonization, I wonder what exactly happens if human exhalation products are released into Titanian atmosphere and, say, a spark igniter happens to be ...
2
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1answer
91 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 ...
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2answers
209 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?
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0answers
70 views

What causes these plume features on Delta IV Heavy?

Just catching up on the Jan 19th launch of NROL-71 on board the Delta IV Heavy and I noticed these very prominent features in the exhaust plumes, beginning around the time the centre core is throttled ...
1
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1answer
145 views

What would happen if air hitting heatshield was ignited?

During Earth's atmospheric entry of an Apollo-like capsule, what would happen if oxygen hitting heatshield was mixed with fuel injected through heatshield, and ignited? Edit & addendum : During ...
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0answers
43 views

Iron powder reaction in chlorate candle [closed]

When a sodium chlorate candle is ignighted, the iron powder is burned to allow the oxygen to be released with the reaction 2NaClO3 → 2NaCl + 3O2 The iron powder is not included in this equation, and ...
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2answers
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?
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1answer
184 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 ...
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1answer
723 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?
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0answers
190 views

Why is Rocketlabs having lengthy combustion chamber?

Looking at different rocket engines, L/D(CC_length/CC_diameter) ratio of combustion chamber is very much less compared to Rocket labs. Even the modern age engines like Merlin 1d and Raptor engines ...
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0answers
71 views

Is it undesirable for LOx to splash on the walls of combustion chamber?

Typically, there are annular ports on the injector plate to introduce fuel to cool the combustion chamber. Why is LOx not used for cooling despite it being extremely cold? Given there will be a lot ...
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1answer
321 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 ...
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2answers
2k 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 ...
16
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4answers
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 ...
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0answers
142 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 ...
6
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2answers
115 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 ...
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2answers
356 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 ...
2
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1answer
711 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 ...
3
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1answer
265 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 ...
3
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1answer
646 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 ...
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1answer
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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 ...
6
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1answer
7k 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 ...
32
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6answers
10k views

Why do rocket nozzles open near the end?

Question: Why do rocket nozzles open wider at the end than, let's say, get narrower? Let me explain: I recently learned from random internet sources, that a jet engine works by having this amazing ...
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1answer
142 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 ...
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2answers
928 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 ...
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1answer
274 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 ...
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1answer
419 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 ...
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1answer
420 views

Controlling Combustion Chamber Pressure

When designing a rocket engine, what degrees of freedom do you have to get the combustion chamber to a desired pressure? I assume you have mass flow rate, type and mixture ratio of fuel and oxidizer, ...
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3answers
494 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 ...
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4answers
12k 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. ...
2
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2answers
496 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 ...
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1answer
969 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. (...