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Questions tagged [nozzle]

Questions regarding the rocket engine nozzles, semi-open compartments of various shapes and sizes into which propellant components are injected by their own pressure or with a help of a turbine, often preheated and ignited to start a thermochemical reaction in the nozzle's combustion chamber, producing thrust with expansion into gases and ejecting them through the nozzle's exhaust as plumes, accelerating the rocket to high-mach velocities.

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Why does the Superdraco exhaust seem so under-expanded in this photo?

The Ars Technica articles From zero to 100mph in 1.2 seconds, the SuperDraco thruster delivers Dragon was destroyed just before the firing of its SuperDraco thrusters both include this "file photo" ...
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What are these big shiny metallic “lumps” on the bottom edge of each Falcon Heavy nozzle?

What are these big shiny metallic "lumps" on the bottom edge of each nozzle of each core of this Falcon Heavy image from the Teslarati article SpaceX reveals Falcon Heavy Block 5 in first official ...
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1answer
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What is the white spray-pattern residue inside these Falcon Heavy nozzles?

What is the white residue in a spray pattern seen on the inside of each nozzle of each side core of this Falcon Heavy image from the Teslarati article SpaceX reveals Falcon Heavy Block 5 in first ...
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Issue with units for a rocket nozzle throat area problem

I'm working through How to Design, Build, and Test Small Liquid-Fuel Rocket Engines. The guide explains calculating a rocket nozzle throat area using Eq. (7): $$A_t = \frac{w_t}{P_t} \sqrt{\frac{R ...
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1answer
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Weight Flow Rate

I read in the book INTRODUCTION TO ROCKET SCIENCE AND ENGINEERING by T.S.T that Rocket Engineers design how big the throat of the nozzle should be based on the Weight Flow Rate. So my question is HOW?
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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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1answer
100 views

How is the exit velocity of the flow in a sounding rocket nozzle?

How is the exit velocity of the flow in a sounding rocket nozzle? Is it subsonic or supersonic? Is a de Laval nozzle required for sounding rockets? Bonus Question: What about Model Rockets?
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Could ablative material sublimation slow down a spacecraft?

Thought experiment illustrated below: Suppose a weird spacecraft entering Earth's atmosphere from low Earth orbit, payload first. Behind it there is an inverted nozzle shaped structure, attached with ...
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Why are exhaust nozzles in space shaped the way they are? [duplicate]

Why are nozzles in space shaped like a cone and not like a tube ensuring all the exhaust is directed strait?
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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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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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What causes those curtain-like hot and cool spots in the 2nd stage nozzle of this Electron ELaNa 19 launch?

Here is a GIF that I made of the recent Electron Launch from frame grabs in the Rocket Lab video ELaNa 19 Launch - 12/16/2018 It is about 4M, so it won't fit in SE's normal image import. Frames are ...
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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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1answer
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Are there rocket nozzles that use non-elliptical shapes?

I was reading this question: Why the non-symmetric design of rocket nozzles? Which got me thinking, have there been any nozzles that don't end in an ellipse? Even the one in that question ends in a ...
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Why is SpaceShipTwo's nozzle scarfed? [duplicate]

As seen in this photo (from here) there appears to be a significant scarf to the nozzle. I'm familiar with scarfing reaction control jet nozzles to fit fuselage contours, but this one is completely ...
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1answer
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Analytical approximations for the shapes of these plots of ISP vs nozzle diameter? (Raptor engine)

A comment on the currently unanswered question Is there an authoritative catalog for rocket launch identifiers? led me to this Github page which links to r/spacexlounge on which currently appears a ...
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Nozzle extension(skirt) attachment mechanism

I am looking for the nozzle skirt attachment mechanism, for RocketLab it looks like nuts and bolts and for SpaceX I don't have any idea. If anybody have any reference for what mechanism should be ...
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Nozzle skirt in the second stage of Rocketlab's Electron [duplicate]

As we can see, in the first stage of Rocketlab's Electron the nozzles have small nozzle exit area. Source (all) But for second stage why are they using nozzle skirt/ extension with huge exit area?
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F1 engine specification?

I am collecting the engine specification data of different engines. I want to know the nozzle length and combustion chamber length and diameter of the F1 engine of Saturn-5. Please give some ...
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1answer
676 views

Red color in the nozzles of Soyuz-2 rocket engines RD-107 and RD-108, is it only a decoration?

Many pictures of the Soyuz-2 show the inside of the nozzles painted with a brilliant red. Is there any function of the paint during ignition and operation of the rocket engines, or is it just a ...
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1answer
232 views

new nozzle design, is it a fail?

So I'm an amature rocket scientist. while having a conversation with a friend on a nozzles we though of a new nozzle: Its a double nozzle where it expands a lot and then compress. I want to put this ...
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1answer
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How might an internal combustion engine generate substantial external thrust?

This answer mentions the proposed use of an internal combustion engine (ICE) in ULA's ACES upper stage to extract energy from LH2/LOX in multiple forms for multiple uses, which is described further in ...
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Where does the thrust act in a rocket engine and how is it transferred to rocket structure?

A rocket engine is basically a device that generates a high pressure inside the chamber and the pressure difference creates a force. A nozzle helps in effectively accelerating the flow and increases ...
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1answer
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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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1answer
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How to design a bell nozzle from scratch [closed]

I need help creating my own custom model rocket nozzle. I'm making a model rocket, it will have many intricate parts, but the most intricate maybe the nozzle. My question is where do I start if I want ...
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1answer
597 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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Did I see the Formosat-5 F9 2nd stage nozzle vibrate at about 2Hz at SECO-1?

Did I see the F9 2nd stage nozzle vibrate at about 2Hz at SECO-1? It looked like the bottom of the bell vibrated in an elliptical shape. Did I imagine that? Has this happened before? $\hskip 3.4 cm$...
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1answer
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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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1answer
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Why are exhaust flames “jumping around” the bases of the Falcon-9 engine nozzles; NROL-76? [duplicate]

I see something interesting the webcast of the NROL-76 launch. At around T+00:00:55 it looks like flames from the exhaust start jumping around the bases of the ring ...
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1answer
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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 ...
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1answer
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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??
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1answer
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Why is the X-37B's large nozzle offset to right from the spacecraft's mid-plane?

Perhaps I'm naive to think that the single large nozzle at the back of the X-37B is a nozzle for an engine, but regardless of the purpose, gas exiting from a nozzle will produce thrust. Is the X-37B's ...
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1answer
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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 ...
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1answer
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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 ...
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J-2 rocket nozzle length

The total length of the J-2 rocket engine is 133 inches, but what is its nozzle length from throat to exit?
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What are the pros and cons of expansion-deflection nozzle?

From the Wikipedia, E-D nozzle works similarly to aerospike nozzle which compensates the exhaust gas in the atmosphere to increase specific impulse.
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1answer
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Was a large-nozzle variant of the J-2 ever considered?

The J-2 engine used on the upper stages of the Saturn launchers has a specific impulse in vacuum of 421 seconds. This is substantially lower than that of the smaller RL10, 440-460 seconds depending on ...
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1answer
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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 ...
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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 ...
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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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What is this yellow light on the side of the 2nd stage nozzle - Shenzhou-11 launch

According to Wikipedia the single engine on the 2nd stage is a YF-20 series engine. What is causing the faint yellow light on the side of the nozzle where there is a tube wrapped around it? above: ...
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How much efficiency is lost from a fixed De Laval nozzle when modified for atmospheric use?

Fixed nozzles designed for vacuum are larger/broader than those designed for atmospheric or combined air/space use, which have less flanged nozzles due to the drag a larger flange would incur in the ...
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Can someone tell me the effect on performance of overexpanded nozzles?

I understand that underexpanded nozzles lose efficiency, due to untapped potential in the gas before exiting the nozzle, but what happens to overexpanded nozzles? I understand that the pressure of the ...
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How complex is the science of a fixed nozzle shape?

Obviously in the simplest variant it's not complex at all. I've seen amateur rocket engine nozzles shaped through applying a nail to packed clay layer. How complex is the science behind the shape of ...
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1answer
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What's the nature of hoop stresses on a rocket nozzle?

On a rocket nozzle, are the stresses (namely hoop stresses) from pressure differentials compressive or tensile? Obviously, in a combustion chamber, the pressure inside is greater than outside. As ...
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1answer
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Is there any rule for rocket engine nozzle proximity from each other?

I wonder if there is any rule for how closely you can put engine nozzles to each other. Are there any vibration, heat, etc. constraints when you are assembling two or more engine bells together? ...
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1answer
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In space, how far from the nozzle is the exhaust from a space-craft capable of causing damage?

I suspect the question may be a trifle subjective; dependent upon the nature of the propulsion system, the energy levels, as also the nature of the object impinged The exhaust from a space-craft is ...
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Why are the exhaust plumes exiting the nozzles of SpaceShip Two segmented along their length?

Here is a photo of SpaceShip 2's exhaust shortly after ignition during the test flight in January Why do they have that segmented structure, and how does it affect thrust?
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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?
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Convergent-Divergent / De Laval Nozzle Dimensions

I'm creating a super sonic ping pong ball cannon like the one recently shown on Mythbusters. I plan on using pressure rated steel pipe so it's as safe as realistically possible and showing it off at ...