Questions tagged [engine-design]

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

36 questions with no upvoted or accepted answers
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6
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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 ...
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479 views

What upgrades does the Merlin 1D need to increase its time between overhauls to 1000 hours?

This is a question I've been pondering for the last few weeks after I back-calculated the details of the Merlin 1D engine. Just as a thought exercise, I wanted to see what upgrades the Merlin 1D would ...
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151 views

What modifications constituted the ‘reorificing’ of F-1 engines on later Saturn V flights?

The topic of uprating the Saturn V’s first stage engines appears to have been widely discussed, and yet there is little agreement as to how it was done. Early Rocketdyne F-1 engines quote lower ...
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153 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 ...
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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 ...
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80 views

Maximum speed of rocket propellant flow?

In reading this question (Limiting factors of liquid rocket engine thrust), it prompts me to ask if there is an upper limit in how fast the propellant/oxidizer can be pumped into a combustion chamber ...
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69 views

Why doesn't a regeneratively cooled engine crack due to differential expansion induced by thermal gradients?

A liquid rocket engine with regeneratively cooled chamber walls and nozzles would definitely be one among those components experiencing the steepest thermal gradients (Chamber wall inner - $3000 K$ ...
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175 views

Does Rocket Lab's Rutherford have margin for uprating with improved battery technology?

We've seen with SpaceX's Merlin engines that the initial design had a lot of headroom for subsequent increases in chamber pressure and mass flow rate (from supercooling and densification) to gain ...
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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 ...
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 ...
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37 views

Storage density of a Deuterium-Helium 3 fusion pellet

in a series I am working on I will be using a D-He3 fusion drive system (similar to the one in the expanse according to Project RHO). I am under the assumption that the fuel will be stored in a pellet ...
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229 views

What is the function of this Merlin engine's tube, and why is it getting red hot?

In the video of the recent SpaceX Starlink launch, one view of the Falcon-9 2nd stage engine shows a cane-shaped tube that glows red hot at the "handle" end and seems to get hotter over time....
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127 views

Why did the nozzles on the SRB's igniter initiator point toward the grain of the main igniter while the main igniter's nozzle pointed straight down?

How did the shuttle designers make those decisions? What made it a better decision to point the exhaust of the igniter initiator toward the main igniter's grain at an angle? What made it a better ...
3
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1answer
226 views

Does engine purging cause dry run of turbo pump in a liquid rocket engine? If it occurs, what is the implication?

Does engine purging in a liquid rocket engine cause dry run of the turbopump? If so, does that have any implication for the design, health, maintenance, or operation of the pump? How do we calculate ...
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174 views

Does LOx stay as liquid when entering combustion chamber?

Given the heat from combustion and increased temperature, would the LOx still be in liquid form after emanating from the injector? Or will it instantly transform into gas? Are injectors cooled using ...
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145 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 ...
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24 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 ...
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134 views

Would this 'hybrid expander cycle' engine be practical?

This is another attempt at making closed expander cycle a bit more efficient (the first attempt was here). The design combines some elements of both the open and the closed expander cycles (hence the "...
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61 views

Deep throttling in sea level engines

In this excellent answer, asked for merlin engines deep throttling in first stage and produced here. To help you understand where the cross over point is, here is some math for understanding the ...
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48 views

Are there any staged combustion cycle rocket engines under 1000 kN? Is it easier to produce larger engines with this type of engine cycle?

I found that most engines developed with staged combustion cycles are inherently quite powerful. Are there any engines which was developed with the staged combustion cycle with a thrust under 1 MN. ...
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45 views

What are some common exit pressures for liquid propellant engines?

Most engines are overexpanded at launch so that they reach peak efficiency at altitude. It’s easy to find values for thrust, specific impulse, expansion ratio, chamber pressure, etc, but I’m trying to ...
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104 views

Layout of regenerative cooling tubing?

In F1, and space shuttle engines (I think), the regenerative cooling tubing goes through the inner wall of the nozzle. The russian engines (RD-180 and likes) seem to have smooth inner and outer ...
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110 views

How to overcome the challenge of igniting kerosene using spark plugs?

Discussions in this question and its answer, concerning the use of spark plug ignition for Kero/GOx system outlines the energy limitations of spark plugs to ignite the mixture. But Ignition Transient ...
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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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198 views

Orbit to Orbit Transport Stage

Would it be faster or cheaper to have a lander, SSTO, and/or SpaceX Mars rocket to rendezvous connect with a more efficient engine or "transport stage" or another lander, SSTO? When the spacecraft ...
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712 views

Rao contour nozzle: Calculate throat and exit angle?

The Rao nozzle formula is an empiric formula for a parabolic nozzle used in pretty much all nozzles today. The problem is it depends on the throat and exit-angle of the nozzle, which varies with ...
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212 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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97 views

Detaching parts of engine bell

I was looking at engine bells, and I was wondering: would it be possible or useful for a diamond shaped engine bell, that would stage sections off, creating a wider bell as the rocket leaves the ...
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55 views

Which is preferred for liquid atomization - gas & liquid shear or liquid & liquid shear?

For generating a spray of droplets, liquid need to be disintegrated/atomized through shear forces. Typical injectors in IC engines and aircraft use shear between gas & liquid at the phase ...
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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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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 ...
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282 views

Pintle injector in a Vortex Cooled Chamber Wall (VCCW) Engine

All the articles I have found show the VCCW engines using flat plate injectors. With the inherent combustion stability of a Pintle injector system, it would seem to be a better choice, yet I find no ...
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Why was circa 600 volts used for DAWN's ion propulsion?

This answer estimates that the DAWN spacecraft's solar-electric propulsion accelerated about 3 milligrams of Xe+1 per second, using roughly 1350 Watts of electrical power. I estimate that 3 mg/sec of ...
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142 views

How do toroidal and linear aerospike nozzles compare?

What are the pro's and con's of toroidal and linear aerospike engines with respect to each other? When does one choose one design over the other? A linear aerospike is characterized by multiple ...
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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 ...
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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 ...