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Questions tagged [engine-design]

Questions regarding the design or design process for a propulsion system.

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27
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4answers
4k views

Does the NK-33 engine require subcooled kerosene so cold that it turns to wax?

It was mentioned in this answer and in several other places on the internet that the kerosene fuel used by NK-33 engines needed to be subcooled enough so that it reached the same density as the LOX, ...
10
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1answer
6k views

Rocket Engine Plumbing: Still don't understand the Full Flow Staged Combustion Cycle

I just found this incredible video KSP Doesn't Teach: Rocket Engine Plumbing and ran through it a few times. It's very helpful in the way it outlines the various issues first, and then designs the ...
12
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2answers
2k views

Disposition of the Oxidizer Tank in Rockets with Autogenous Pressurization

A little while ago, Ars Technica did a big story on the Firefly rocket under development. http://arstechnica.com/science/2014/11/firefly-space-systems-charges-full-speed-toward-low-earth-orbit/2/ A ...
10
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3answers
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What are the phases of ignition (and flameout) of a liquid fuel engine?

As I observed ignition of several rocket engines (Shuttle, AMDE, Lynx Suborbital, Saturn V) they all come through a couple phases - emitting various vapors, unfocused flame, etc, before the proper "...
4
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3answers
486 views

Can a solar sail be added to an ion engine and work better?

Has there been a concept vehicle that uses both solar sails and ion engines? Does the added mass of each system increase or reduce the spacecrafts total delta V capabilities? Inspired by S.F. As S.F....
4
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1answer
1k views

What are the two very large “blue” cylinders attaching to the combustion chamber of each Rutherford Engine?

The NASA Spaceflight article Rocket Lab’s Electron rocket set for inaugural flight from New Zealand mentions the upcoming opening of a 10 day launch window: Rocket Lab, a U.S.-based launch service ...
23
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7answers
15k views

Why aren't linear aerospike engines in common use?

Linear aerospike engines are an old idea that seem so full of promise. Why are they not widely used today by the likes of Boeing, SpaceX, etc.?
12
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1answer
3k views

How are rocket nozzles made?

How are rocket nozzles made?? Is it a huge chunk of metal that they cut down or is it a "pipe" that they reshape? Or something else??
12
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3answers
3k views

Did any rockets use differential throttling instead of gimbal?

It seems the standard approach to control of rockets during launch is either vernier thrusters, or gimbals on the main engines. Sure that works, and is quite efficient, but I wonder about a simpler ...
4
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4answers
1k views

What kind of engine does this Isp = 1600 refer to? Is it cubesat-friendly?

These two good answers (one and two) to the question "Is there a maximum Isp for 'exothermic chemical reaction rockets?'" put the limits around 500-550 seconds for the limits of practical chemical ...
67
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10answers
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Why is SpaceX considering Methane as fuel for their next engine, the Raptor?

Currently, SpaceX has developed the Merlin 1 family (1B (Falcon 1), 1C (Falcon 9 v1.0), 1D (Falcon 9 v1.1/F9-R/Falcon Heavy), vacuum versions and sealevel versions) which are LOX/RP1 based. (75-...
28
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7answers
12k views

Why are Rocket engines at the base of the rocket?

I don't know much about Rockets, but all that I have seen, from the Saturn V to SpaceX's Falcon 9 have the engine at the bottom. Doesn't this make the Rocket really unstable, like balancing a pencil ...
37
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3answers
11k views

Why are rocket engines operating above 100% often considered nominal?

It was brought to the attention of the community that right before the crash of Antares the commentator noted: "Main engines at 108%" It was noted that other engines were also reported to work at ...
5
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1answer
2k views

How can phenolic (resin?) handle rocket engine nozzle temperatures?

I just saw @OrganicMarble's survey answer that bravely tackles the wide variety of technologies used to make different types of rocket nozzles. One item caught my eye: Nozzles may also be made of ...
21
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2answers
3k views

Are nuclear-powered engines the way to go for space exploration?

I often think about the future of humanity and how to achieve it. Despite criticism, the USA and USSR achieved significant scientific breakthroughs, such as: putting the first man in space landing ...
5
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0answers
1k views

What kind of forces and response times/accelerations are needed to gimbal a mid-sized nine-engine rocket's engines?

This answer explains that the gimbaling actuators on each of the nine Rutherford engines on the Electron rocket are in fact electrically powered DC brushless motors. Currently it's not known if they ...
17
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1answer
2k views

Why the non-symmetric design of rocket nozzles?

Although I have seen many perfectly symmetric nozzles, I have also seen designs such as this (Virgin Galactic) which is only symmetrical about one axis: Why is this?
12
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1answer
2k views

Why was the Apollo CM main engine thought to be unreliable on Apollo 13?

When Apollo 13 had most of its internal systems destroyed by an explosion, NASA decided that the best course of action would be to fire the main engine on the dark side of the moon to send the capsule ...
11
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4answers
2k views

Do rocket engines have shock absorbers?

With a million pounds of thrust and many g of acceleration and a significant fraction of a g of vibration, connecting the engine to the rocket can't be trivial. At launch the mass is very high and ...
2
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4answers
686 views

In the context of calculating mass flow rate from thrust and Isp, how would an additional efficiency be defined?

In this answer I show a quickie derivation for calculating a mass flow rate of a rocket from a known thrust and Isp. A comment there says: That assumes 100% efficiency and ignores the fuel ...
2
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1answer
538 views

Why is the Merlin 1D Vacuum nozzle bigger than the Merlin 1D nozzle?

I know that the Merlin 1D is used in the Falcon first stage and the Merlin 1D Vac in the second stage but i can't find any information as to why the nozzle has to be bigger in vaccuum. I guess that a ...
1
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1answer
395 views

How does the Space Shuttle's SSME engine's thrust vary after ignition?

After writing the question Do Blue Origin's BE-3 engines need to run for 7 seconds to “warm up”?, I took a look at the YouTube video SSME ignition sequence (found in What are the small gas jets at the ...
18
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2answers
3k views

Why do pressure fed engines have combustion instabilities?

Reading about the Sea Dragon idea, I came upon this argument against it, which sounds compelling, but relies on more detailed knowledge than I have: Those are to be pressure-fed to avoid "...
24
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1answer
2k views

How realistic would the Sea Dragon engine be to produce given today's technology?

Just learned of the Sea Dragon proposal from back in 1962. From the Wikipedia entry The first stage was to be powered by a single enormous 80,000,000 pounds-force (360 MN) thrust engine burning RP-...
19
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7answers
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Can ion thrusters be scaled up?

All ion thrusters are quite small. Having read through the more approachable information about them, as they use physics pretty beyond me, I don't understand what it is about them that makes it ...
14
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1answer
2k views

Changes made to ISRO GSLV-D5's CUS and FBTP since GSLV-D3's LH2/LOX CUS failure to sustain ignition?

The launch of the ISRO GSLV-D5 launching India's GSAT 14 advanced communications satellite (weighing 1,980 kg) is slated for 19th of August, 2013, flying in the GSLV Mk.2 configuration with an Indian-...
6
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1answer
302 views

Could oxygen be used in a resistojet in a vacuum environment?

Resistojets heat a compressed gas or vaporize a liquid to expand it through a nozzle for thrust. They improve a bit on the performance of cold gas thrusters. This experimental water resistojet managed ...
32
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6answers
6k views

Why did it take so long for methane to be used as a rocket propellant?

SpaceX have put methane on the map as a rocket fuel, but they weren't the first to consider its use. The first experiments in building a rocket engine that uses methane date back to 2007. Now methane ...
5
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2answers
360 views

Pro/cons of burning propellant in stochiometric ratio?

Several questions and answers here speak of stochiometric ratio. I do understand it is convinient for efficiency (greater ISP). I also read somewhere (I am unable ro find again the reference, it was ...
4
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1answer
2k views

How to seal the connection between the combustion chamber and outer shell in this rocket engine model?

Here is rocket engine drawing. The combustion chamber made from copper and the outer shell from stainless steel. The coolant, either water or gasoline will be between With either pressurised water or ...
4
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1answer
268 views

How often can liquid hydrogen engines be restarted?

A proposal for lunar development, LunarCOTS, relies on a reusable shuttle running on LH2 and LOX to work. It lands, is refueled on the lunar surface, and then takes off again. Presumably it could sit ...
12
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1answer
2k views

Merlin 1D Engine Throttling

How does the SpaceX Merlin engine control the mass flow rate to throttle its thrust? Do the pintle injectors move? Does the mass flow rate to the gas generator change?
5
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1answer
164 views

What are some of the important parameters to scaling a liquid rocket engine

Liquid Rocket Engines can be clustered together on a stage but their performance, weight and size largely decide and constrain the design of the launcher. Data on the newer smaller launcher engines ...
3
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5answers
1k views

Could rockets launched from the ground use wings in the stages?

Could a slower or smaller rocket take advantage of lift if all the stages had wings? Could the stages reduce splashdown impact forces by using a spinning seedpod-like design (as shown in the image ...
3
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1answer
1k views

What is the 'Summerfield criterion' regarding rocket exhaust expansion

In this question the 'Summerfield criterion' is mentioned. Saying that 'Historically, the Summerfield criterion was used, where the minimum pressure in a nozzle must be greater than 0.35...0.4*...
2
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1answer
1k views

Problems with the “How to Design, Build and Test Small Liquid-Fuel Rocket Engines” text

For those that have read or consulted the text: How to Design, Build and Test Small Liquid-Fuel Rocket Engines (Rocketlab/China Lake). Otherwise, see steps 10-13 here: https://risacher.org/rocket/...
12
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2answers
2k views

Quality vs. Quantity for Rocket Engines

I read a while ago about the famous Soviet N-1, called by some the most powerful rocket (in terms of thrust at liftoff) in history. It used an incredible 30 engines in its first stage. The American ...
11
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1answer
634 views

Why does the YF-75D nozzle have such a strong spiral pattern?

Why does the YF-75D nozzle material have such a strong spiral pattern? Is it a result/biproduct of a manufacturing process only, or does it have some specific function? edit: The last, cropped ...
10
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2answers
623 views

Can a booster be designed to withstand 10,000 Gs?

In Could any existing gun reach the Karman Line?, Richard Graf's Kickstarter campaign for his Starfire space-gun is referenced & discussed. Setting aside my native skepticism for a project with ...
7
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3answers
2k views

How does a launch vehicle control its trajectory during the first stage?

It appears during most launches that the only engines working are the main first stage engines. It was my understanding that these engines are fixed in place and cannot turn the rocket, but I must be ...
6
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1answer
200 views

Why do some engines have so many little tubes, and others, not so much?

This comment about the Houston Space Center's Rocket Garden drew my attention to the cropped image below, from that link. I'm under the impression that some liquid propellant engines don't have a ...
3
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3answers
338 views

At what size does a bigger solar sail stop increasing your acceleration?

Is there a point where the larger solar sail would not add more thrust? What is the most thrust a solar sail can produce? Can a solar sail be added to an ion engine and work better?
3
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1answer
455 views

When this F9 2nd stage engine suddenly moves upon shutdown, is it moving along the rocket's axis?

The GIFs are made from frames of the live broadcast of SpaceX JCSat-16 2nd stage around the time of the second engine cut-off (SECO-2). It looks like the engine moves outward axially as the thrust ...
2
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2answers
303 views

Would a self-winding watch work in space without gravity?

Could a watch that winds itself with a pendulum work in space with no gravity? Could a pendulum or the self winding part be modified to work off the movements of the wrist in a microgravity ...
2
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1answer
228 views

How do you determine what the temperature will be in the combustion chamber of a rocket engine?

I am guessing it is dependent on the fuel and oxidiser and the chamber pressure but is there an equation that would calculate the chamber temperature?
2
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1answer
483 views

What is the highest gimbal range ever used on an engine?

This answer here mentions the STS-94's ability to gimbal up to 20 degrees in all directions, that got me thinking, what exactly is the maximum ever feasibly implemented? I've seen a lot of information ...
1
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1answer
86 views

Does an engine's Isp rating always include all mass flow rates, including those for electrical or mechanical power generations?

Discussions here have convinced me to ask this separately. Isp or mass-specific impulse is a ratio of thrust (force) to mass flow rate (kg/s). It comes in two flavors, seconds and meters/second ...
1
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2answers
477 views

What performance specification would be lower for Krypton than for Xenon in Hall effect thrusters?

The Ars Technica article SpaceX scrubs first attempt to launch 60 Internet satellites [Updated] (found here) discusses the use of Krypton rather than Xenon in the Starlink Hall effect ion thrusters: ...
0
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0answers
285 views

How was the Stabilo crewed re-entry vehicle supposed to work? A tractor engine with four nozzles?

ARCA Space's webpage for the Stabilo program has a description and an image. Hydrogen peroxide monopropellant? Reaction closer to the crew than the nozzle? With thrust at the top, it seems that ...
16
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1answer
9k views

Why is the Russian approach to the aerodynamics of their rockets different?

Russian rockets look like this: They flare them out at the bottom. With their newest rocket, the Proton, the flared shape is gone but the boosters still have caps that angle in towards the main ...