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Questions tagged [engines]

Questions regarding equipment used to propel a spacecraft or a rocket. Questions about attitude control jets should be tagged "attitude".

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Why should nozzles be perfectly expanded?

If I understand it correctly, the only problem with an overexpanded nozzle is (aside from technical difficulties) that the surrounding atmosphere puts pressure on the exhaust gases and reduces engine ...
Saturn V's user avatar
  • 1,335
1 vote
0 answers
71 views

What is the ratio of air and ethyl alcohol that must be in order to power a rocket engine? [closed]

There is a rocket engine that will run on a fuel pair: air + ethyl alcohol, but what percentage of components should be supplied ...
DYNAMIC AEROSPACE's user avatar
4 votes
1 answer
197 views

Theoretical viability of a liquid rocket engine concept [closed]

[DISCLAIMER: I am an aerospace engineer undergrad and I do NOT want to build this. I wanted to come up with an alternative for the usual hypergolic mix so US military personnel would have one less ...
user avatar
2 votes
1 answer
397 views

What rocket engine is this?

I came across a meme depicting a supposedly oxygen rich, fuel rich, and "engine rich" cycle of rocket engine. However, I'm pretty sure at least one of them is incorrect listing what looks a ...
fyrepenguin's user avatar
  • 1,670
2 votes
0 answers
41 views

How to calculate the cooling jacket of a liquid propellant engine with an external component? [closed]

When designing a small rocket engine with a thrust of 100 N, questions arose about the cooling of the combustion chamber and the nozzle apparatus. It was decided to ...
DYNAMIC AEROSPACE's user avatar
0 votes
1 answer
171 views

Does Raptor rocket engine of SpaceX include a cracker or fuel conversion system to crack the hydrocarbon fuel into its constituents?

In the Raptor rocket engine, where is the hot turbine exhaust gas transferred, when gaseous fuel arrives from the heat exchanger? Does the Raptor rocket engine include a cracker or fuel conversion ...
Lakshay's user avatar
  • 11
10 votes
2 answers
2k views

Hydrazine and liquid fluorine as a semi-cryogenic storable lunar space propellant

The use of liquid fluorine as an oxidizer diluted with liquid oxygen has been tested, but wasn't flown, by Bell and Rocketdyne, seperately. http://www.astronautix.com/l/lf2hydrazine.html It was ...
AnarchoEngineer's user avatar
1 vote
0 answers
51 views

Combustion chamber pressure calculation [duplicate]

A liquid propellent rocket engine: how is combustion chamber pressure calculated? Is it the different between turbopump outlet pressure and the drop in the injectors (losses aside)? Thanks!
Mariner's user avatar
  • 11
4 votes
2 answers
270 views

Engine most likely to be available in the next 80 years to accelerate a craft at 1G for 4 weeks [closed]

I am wondering what type of engine would most likely be available in the next 80 that can constantly accelerate a spacecraft at 1G. Preferably, it could accelerate it for 4 weeks. The engine could be ...
Tom's user avatar
  • 141
5 votes
0 answers
218 views

What are the arms for under the nozzle of NASA engine tests?

When NASA tests rocket engines at the Stennis Space Center, the engines have two arms under the nozzle. When the engines start these arms swing out of the way of the exhaust. What are these arms for? ...
Tom's user avatar
  • 51
2 votes
1 answer
284 views

Why aren't more companies manufacturing the RS-25 (Space Shuttle Main Engine)?

The RS-25 is a great engine with a terrific ISP. It was used 42 years ago (on April 12th 1981) for the first Space Shuttle flight; therefore, the most of the patents on it must have expired long ago. ...
phil1008's user avatar
  • 5,642
4 votes
1 answer
177 views

How would one identify ionic thrust vs chemical thrust in an orbit transfer?

My nomenclature might be a bit off, I’m no expert but I’ve been reading to solve the question all the same. Say we detect an orbit transfer based off ephemeris records. We can get the 6 classic orbit ...
Dylan's user avatar
  • 321
0 votes
0 answers
159 views

Can an orbital rocket have an airplane first stage? [duplicate]

The first stage of SpaceX's Nov 18 Starship launch was the Super Heavy. According to the Wikipedia page, it packs 3,400 tones of fuel. In the launch video, it shows the rocket reaches 27 km of ...
paki eng's user avatar
  • 147
1 vote
0 answers
99 views

Single shaft turbopump vs two turbopumps

What are the pros and cons of using same turbopump for fuel and oxidizer and using 2 different pumps for both?
Rocketsss's user avatar
0 votes
0 answers
84 views

Dual expander bleed cycle

Would dual expander bleed cycle be a good idea? The lox will pass through the nozzle and drive the lox pump And the fuel will also pass through the nozzle to drive the fuel pump Both will be expander ...
Guest12345's user avatar
3 votes
0 answers
147 views

What are the major tradeoffs for a launch vehicle having either one 400 kN engine or eight 50 kN engines?

Given the problem of choosing to build and launch a small rocket to put a smallsat into orbit with either of these two configurations, what are the major tradeoffs between them? For specific issues ...
Muhammad Ahsan's user avatar
1 vote
2 answers
319 views

Can hydrogen peroxide and propane be a good rocket propellant combination?

The decomposition of hydrogen peroxide can be used to spin the turbopump and then it can be mixed with propane in the combustion chamber
Guest12345's user avatar
0 votes
0 answers
45 views

How to calculate the tank boost system for the displacement feed system?

There is a liquid rocket engine running on two components: highly concentrated hydrogen peroxide and kerosene, fuel vapor is ...
Андрей Александров's user avatar
0 votes
1 answer
93 views

Semi-Cryogenic HTP/LH2 engine?

Also see HTP as oxidizer for main propulsion (for more info on history of H2O2/HTP in rocketry) Note: HTP and H2O2 will be used interchangeably I know the Black Arrow LV (The first orbital lipstick) ...
AnarchoEngineer's user avatar
2 votes
1 answer
101 views

Combustion stability for the second stage of Sea Dragon

I was listening to a video about SHLV's (Super Heavy Launch Vehicles), and Sea Dragon's first stage engine was mentioned. In terms of combustions stability, the suggested fix would be large combustion ...
AnarchoEngineer's user avatar
15 votes
4 answers
4k views

Do all artificial satellites have engines?

Novice question. A few days ago I watched a TV documentary about Virgin Orbit’s failed mission earlier this year to send satellites into orbit from Spaceport Cornwall. One of the satellites shown ...
Peter4075's user avatar
  • 253
2 votes
0 answers
104 views

Help with designing nozzle geometry for compressed air thruster

I am designing a compressed air thruster with a conical nozzle geometry. The general design consists of a compressed air tank, pneumatic tubing, and then the actual chamber with the nozzle. The ...
Kyle's user avatar
  • 21
7 votes
2 answers
967 views

Why do methane engines require burn-off igniters?

When I was watching the flight readiness test firing of the Vulcan’s BE-4 engines, I noticed that there were igniters similar to the ROFI igniters seen on liquid hydrogen rockets. Why do methane ...
TRK's user avatar
  • 199
1 vote
1 answer
2k views

Why was Booster 9's 29 engine static fire ended 2.36 seconds early? [duplicate]

Suggested by Darth Pseudonym in answer to my other similar question. Recently (August 7), Booster 9 conducted a static fire test where it shutdown after only 2.74 of the planned 5 seconds of burn ...
Starship - On Strike's user avatar
1 vote
1 answer
213 views

The Boeing Big Onion - Why not use the atmospheric engines on landing?

https://www.aerospaceprojectsreview.com/blog/?p=1325 In relation the the Boeing "Big Onion" SSTO LV, I was doing some brief digging on it's flight profile. (See the awesome Hazegrayart ...
AnarchoEngineer's user avatar
-8 votes
1 answer
208 views

Mathematical inconsistences in rocket fuel [duplicate]

Saturn v is 2882 tons. Fuel is 30gj a tons. Escape velocity (11 km/s). 350 TJ of KE. The fuel is 85 TJ. The Saturn v has 3 times less fuel than it would need to escape gravity.
D J Sims's user avatar
12 votes
3 answers
3k views

Would electrically powered thrusters on JWST have made it last for decades longer?

Since the lifespan of the James Webb Space Telescope is determined by the amount of fuel it can carry for its thrusters, used to decelerate the reaction wheels used to orient the telescope, and since ...
Ryan Christiansen's user avatar
12 votes
2 answers
1k views

Rocket Engine Failure Rate

I am a reciprocating engine machinist and understand that rocket engines are much much more complex. But I am curious why they have such a high failure rate. Even modern rockets are designed to ...
still_learning's user avatar
3 votes
0 answers
118 views

How do ablatively cooled rocket engines compare to regeneratively cooled ones, in terms of mass?

Assuming equivalent thrust and single continuous burn duration, is there a figure that roughly tells the difference in mass between these two engines cooling methods? This question focuses on first ...
user avatar
4 votes
2 answers
298 views

How do Centrifugal Turbopumps work? How do you make one?

I recently visited Wikipedia to look at centrifugal pumps and axial pumps. Centrifugal pumps are very interesting, and I was wondering how they work in more depth. I really don't understand how they ...
Anish's user avatar
  • 41
3 votes
1 answer
126 views

ROFI Temperature

Since hydrogen-fueled rockets usually require Radial Outward Firing Igniters (ROFI), what is the temperature of the sparks from this system? When seen at RS-25/RS-68 ignition, they don't melt but ...
TRK's user avatar
  • 199
10 votes
1 answer
768 views

How common have the various orbital launchers' rocket engines been?

A fleeting thought on my sentiments about the disposability of RS-25s (rare! Only 47 made before the RS-25E/F contracts? Few remain! Complain about them being expended for SLS!) versus Raptors (one ...
Erin Anne's user avatar
  • 11.5k
2 votes
0 answers
106 views

Do smaller engines have a higher thrust to weight ratio?

For a given chamber pressure and shape, thrust is proportional to nozzle area, which is proportional to the square of dimensions mass is proportional to the volume, which is proportional to the cube ...
Abdullah is not an Amalekite's user avatar
2 votes
1 answer
189 views

Can rocket engines produce high voltages?

I was reading Michael Collins' account of the Apollo 11 TLI burn [1], and I wonder wheter the "flashes", "lightning", "sparks flying" and "insistent fireflies" ...
Mister Smith's user avatar
2 votes
2 answers
264 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
-1 votes
1 answer
90 views

Air-Augmentation on a VTO&L super heavy lift

I'm working on a basic design for an Air-Augmented first stage, which boosts the second, expendable, stage from a near-orbit, to allow for deorbit of the second stage. Essentially it's an SSTO that ...
AnarchoEngineer's user avatar
7 votes
1 answer
1k views

Has the ISP been published for NASAs new rotating detonation engine demonstrator?

Nasa just announced successful testing of their new rotating detonation engine: https://www.nasa.gov/centers/marshall/feature/nasa-validates-revolutionary-propulsion-design-for-deep-space-missions I ...
David's user avatar
  • 1,001
0 votes
1 answer
145 views

What would be the most fuel-efficient propulsion solution to accelerate a 100-ton piece of NEO asteroid towards Earth?

We need acceleration to about 300-500 m/s relative to an NEO asteroid - to get to an LEO. What is needed is the lightest package possible, that includes engine, fuel tanks, control module and ...
TheMatrix Equation-balance's user avatar
1 vote
2 answers
806 views

Lorentz force space propulsion

While browsing for Space propulsion, I've found the following article As shown in Figure 2, the conductor I0 gets through the coil L0, and they are fixed together and form a system. a is the main ...
StoyanNikolov's user avatar
24 votes
4 answers
8k views

What is SpaceX doing differently with Starship to avoid it exploding like the N1?

Both Starship and the N1 have more than 30 rocket engines. The N1 exploded after having a chain reaction from a failed engine. N1 rocket engines: Starship’s rocket engines: Unlike the N1, SpaceX has ...
The Rocket fan's user avatar
0 votes
0 answers
57 views

What is a bimodal or multimodal space rocket engine? Especially a nuclear-powered one?

I can't seem to find a specific answer anywhere.... I wonder if it means using the radioactive fuel to power the electronic equipment, purely via natural decay, but also using the same fuel to power a ...
Kurt Hikes's user avatar
3 votes
0 answers
203 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
1 vote
1 answer
161 views

What engine cycle is best for a large lunar lander?

I'm specifically looking for an answer to whether a pressure fed or pump fed engine would be more feasible considering a mass of over 50T(metric, of course), and a single stage to descend and then re-...
AnarchoEngineer's user avatar
1 vote
1 answer
146 views

Is an open expander cycle rocket engine driven by a gasified oxygen turbine technically feasible?

Is an open expander (bleed-off) cycle engine that uses the gasified cryogenic oxidizer instead of the gasified fuel to drive the turbo pumps technically feasible? I was thinking of a first stage open ...
Space Otter's user avatar
0 votes
1 answer
102 views

Thrust & acceleration produced by a rocket engine

For given propellants, with their mass flow decided by the rpm of the turbo pump, what decides the thrust and acceleration produced by a rocket engine? Can we control them independently?
Niranjan's user avatar
  • 3,758
5 votes
4 answers
533 views

What is the most promising fusion technology for rocket propulsion?

Given current fusion technology (barely above q=1 as of the 12/12/22), is a fusion plasma torch rocket engine viable? I'm asking in terms of basic science, not engineering, as I know this would ...
AnarchoEngineer's user avatar
4 votes
2 answers
961 views

Whats the exit pressure of the F-1 engine?

I cant find anything online, does anyone know what it is?
boarbytes's user avatar
6 votes
1 answer
127 views

Proton rocket's engine fizzle

Why does one of Proton's engines sometimes leave a dark gas? Is it some sort of byproduct of the UDMH and NTO reaction or did the engine fail?
Spacey XL's user avatar
2 votes
0 answers
979 views

What is the difference between a spin up test and a spin prime test?

What is the difference between a spin up test and a spin prime test? And if there is no difference, why not just use the first of those two terms, it being more descriptive?
tedtoal's user avatar
  • 121
0 votes
0 answers
49 views

How to test vaccum engines at sea level? [duplicate]

SpaceX is testing its Raptor vacuum engine (RVAC) at sea level (without any facility that can simulate near vacuum conditions). How can they do this without flow separation happening?
ikerdc's user avatar
  • 93

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