Questions tagged [engine-design]

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

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8
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1answer
661 views

How does turbine power output of a full-flow staged combustion engine compare to Oxygen-rich staged combustion?

One of the benefits of the SpaceX Raptor full-flow staged combustion engine is the extra power generated by having all of the fuel and all of the oxidizer flow through the turbines to produce power to ...
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0answers
98 views

What is the largest number of engines ever used on an orbital class rocket? [duplicate]

Specifically the number of engines simultaneously ignited. So not summing up over different stages. I am interested in the max for both number of engines and number of combustion chambers. What I ...
2
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1answer
661 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 ...
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0answers
160 views

Could a high specific impulse chemical rocket be built by using some of the fuel in a closed cycle to heat the exhaust?

There is a fundamental limit to the specific impulse of a chemical rocket because the propellant is also the fuel so you are limited by the fuels energy density. What if you burnt some fuel in a ...
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0answers
93 views

Are fission thermal engines more expensive to develop than chemical engines?

Is there something inherent in the technology of a fission thermal rocket engine that makes it a more expensive endeavour than developing yet another chemical engine? For example because of the ...
5
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624 views

Pulse Rocket Engine

How feasible would a rocket engine that ignited fuel in fast, high pressure pulses be. This type of engine would be especially applicable for low thrust burns such as for the raising of a small ...
3
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1answer
693 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 ...
8
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1answer
3k 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 ...
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 ...
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67 views

What is the mechanism principle of the grid fins in F9? [duplicate]

What is the mechanism principle of the grid fins in F9? or how to design the mechanism for the electricity grid fins? or how to design a electricity folding wing like the grid fins in F9?
6
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1answer
359 views

Understanding Von Braun's Math: Theoretical Isp

I've just read Wernher Von Braun's Project Mars: A Technical Tale, and I'm trying to understand the math in the back. I can follow some of what he's doing, but other parts I just can't tell where his ...
4
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1answer
948 views

At what pressure ratio did the fuel turbopumps of the F1 and J2 operate?

I would like to know the operating points of the fuel-turbo-pumps used in the Saturn rocket engine. (From what I could learn via google, the turbo pump went under the name Mark III) Is there any ...
8
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1answer
276 views

TR-106 under-expansion in sea-level test?

I was looking at pictures of a test fire of a TR-106 engine, and it appears to be fairly under-expanded. What's the reason for this? Does this somehow increase efficiency with this specific engine?
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107 views

Simulation of Rocket chambers like in Hall Effect Thrusters

I started learning Solidworks in hopes of being able to run simulation to study rocket chambers. Currently, I am studying the flow of plasma and its interaction with the magnetic field, but ...
11
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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
3k 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 ...
12
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1answer
4k 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??
8
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2answers
4k views

How is chamber pressure determined for rocket engines?

I've been looking for this for quite some time now, and I can't find anything other than calculations where they already assume a chamber pressure. So my questions are two: What are the equations for ...
7
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3answers
2k views

Is ISP all there is to engine efficiency?

Most rocket engines have their efficiency measured by the specific impulse of the engine, which is just how fast the exhaust of the engine is going. Is there another measure of efficiency that's ...
3
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1answer
403 views

Do gimbaled engines have to be carefully test-fired to ensure the thrust axis intercepts center of rotation?

A smoothly running rocket engine will have a center of thrust axis. If the engine is gimbaled, that axis should pass through each of the gimbal axes (if it's a classical gimbal), or if it is a ball ...
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0answers
2k 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 ...
4
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1answer
2k 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 ...
0
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1answer
146 views

What organizations correspond to the logos on this ORBITEC Vortex engine rocket?

Images are from the 2012 New Atlas article ORBITEC flight tests new vortex liquid fuel rocket engine. One looks a bit like a US military or DoD logo, one perhaps is ATK, but I'm not sure. Is this ...
5
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1answer
1k views

How is chamber pressure and temperature determined for cold gas thrusters?

I'm trying to get some theoretical performance numbers for a cold gas thruster using quasi-one-dimensional flow, and I don't know where to start. For combustion engines you would just take a given ...
30
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3answers
5k views

Why cool engines with fuel as opposed to oxidizer?

As I was watching Tom Mueller describe the Merlin engine, he said that the RP-1 propellant is pumped through ribs in the nozzle to regeneratively cool the engine. Also, a video about Copenhagen ...
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109 views

Electromagnetic engines in heavy radiation regions

What sorts of peculiarities might affect an electromagnetic rocket (VASIMR or Magneto-Inertial Fusion) crossing Jupiter's radiation belts? Could all of that energy fry a magnetic thrust chamber and ...
1
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1answer
360 views

Does all of the fuel in a Staged Combustion Cycle go to the preburner? [duplicate]

Can anyone tell me the difference between staged combustion and full flow staged combustion? Does full flow mean there are 2 preburners (fuel- and oxidiser-rich respectively) or does it mean that ...
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0answers
329 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 ...
12
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1answer
2k views

The principle behind regenerative cooling?

In regenerative cooling the fuel is passed around the nozzle before being pumped into the combustion chamber right? I don't really see how this affects cooling itself, since the heat captured around ...
2
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3answers
507 views

Rocket Engine demonstrator fuel choice

As rocket Science and Space Exploration is becoming more and more popular, I'm currently running some numbers, whether it would be possible to build a rocket engine for showing at schools or ...
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0answers
146 views

Hypergolic slugs with gaseous reactants

Based on points raised in this question about hypergolic slugs. My understanding of a hypergolic slug is that it is a solid or a liquid on a paper patch placed in the combustion chamber and it will ...
2
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1answer
467 views

Could super-cold LOX be used in every rocket engine?

Super-cold LOX gives advantages in performance for a rocket. But it isn't used in all rockets. SpaceX's Merlin 1D rocket engine uses super-cold LOX. Also NK-33 use sub-cooled LOX. Could super-cold LOX ...
4
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1answer
382 views

Ribbed rocket nozzles

A short while ago I visited a real life dissected rocket and it came to my attention that its nozzle is ribbed across its surface. Why would engineers build it this way and what are the advantages ...
7
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1answer
549 views

What are the issues and concerns related to turbopump blade cracks and manned spaceflight?

While the WSJ headline sounds ominous: Congressional Investigators Warn of SpaceX Rocket Defects, Quartz's SpaceX needs to redesign its engine to ensure it is safe for human spaceflight seems to be a ...
5
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1answer
306 views

How to prevent melting too much paraffin in a hybrid LOX-paraffin rocket?

In a hybrid LOX rocket, only the flow of LOX may be controlled. The amount of paraffin melted by heat is determined by the very complex heat transfer from gas to solid paraffin. If the mixture of ...
3
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1answer
999 views

Is it possible to estimate the nozzle characteristics of the Rocketdyne HG3 engine?

Boeing and the Marshall Space Flight Centre brought to pass many studies of improved Saturn V launch vehicles. The rockets proposed under the MLV and ELV projects would feature longer stages for more ...
3
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1answer
294 views

How is the Rocketdyne J-2S area ratio larger than that of the J-2?

The standard J-2 engine measures 3.38 metres in total length, with a nozzle exit diameter of 2.03 metres, to support its 27.5:1 expansion ratio. However, these dimensions are apparently identical for ...
8
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3answers
3k views

Overcoming pressure differential to feed fuel into rocket engines

When pumping fuel and oxidizer into a rocket engine, I presume the pump must create more pressure than the inside of the combustion chamber, otherwise the liquid would back-flow. Is this right? Then ...
4
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1answer
188 views

Build an engine that burns tholins

My idea is to send an hypothetical lander/rover to Titan, and recover from this some samples of rocks... To create a very efficient engine, I suppose to carry only liquid oxygen, and burn the ...
7
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1answer
510 views

Rocket Throttle vs. Jet Throttle

One of the drawbacks of jet engines is that they suffer from turbo lag, whereby a throttle change will take some amount of time to translate to a change in thrust due to the momentum of the turbine ...
10
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1answer
648 views

What was the maximum thrust of the Rocketdyne F-1 engine?

Reading through several old reports, I have come across studies conducted by MSFC on improved Saturn V designs with greater payload capacity, and with uprated engines. As a result of increasing launch ...
12
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1answer
793 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 ...
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 ...
23
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3answers
19k views

What's so special about SpaceX's Raptor rocket engine with 300 Bar chamber pressure?

What allows the Raptor engine to have a high chamber pressure of 300 Bar? Compared to other rocket engines which have been or that are now operational, it has the highest chamber pressure. What does ...
4
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0answers
225 views

How much propellant is “wasted” in the gas generator power cycle?

The gas generator power cycle is an open cycle, with pre-burner exhaust vented after driving the turbine instead of contributing to thrust as in more advanced power cycles. What percentage of the ...
3
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1answer
2k 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*...
10
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1answer
8k 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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4answers
1k views

SpaceX's ITS - why gimbal only the inner cluster?

Does anyone know the reason why, in SpaceX's newly-announced ITS launch vehicle, only the inner cluster gimbals, and not the whole engine system?
2
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2answers
509 views

Some examples of pressure fed engines used on launch vehicles

Are there any examples of pressure fed engines used on launch vehicles? I already know of the ones on the wikipedia page which include Firefly Space Systems OTRAG (rocket) Quad (rocket) of Armadillo ...
4
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1answer
466 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 ...