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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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35
votes
9answers
12k views

Why do rocket nozzles flare?

Why do rocket nozzles open wider at the end than, let's say, get narrower? Let me explain: A jet engine works by having this amazing thing called a combustion chamber. The combustion chamber ignites ...
2
votes
1answer
365 views

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 ...
33
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3answers
6k views

Why do the exhaust flames from cryogenic stage engines appear to be separated from the nozzle?

Why do the exhaust flames from cryogenic stage engines appear to be separated from the nozzle?
12
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1answer
6k 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??
5
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2answers
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 ...
18
votes
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?
13
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1answer
1k 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 ...
5
votes
1answer
426 views

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 ...
2
votes
1answer
865 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 ...
32
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2answers
4k views

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 ...
6
votes
0answers
228 views

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 ...
20
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2answers
2k views

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 ...
8
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1answer
1k views

Is there a diagram of different nozzle diameters to scale?

I am looking for a diagram that shows the different diameters of various nozzle openings, including Rocketdyne's F1 (150 inches) SpaceX's Merlin (66 inches), the Air Force's Delta IV Heavy, and NPO ...
15
votes
2answers
2k views

How hot do rocket engine nozzles get?

What temperatures are encountered by the nozzles of rocket engines like those in SpaceX's Merlin series? Radiative or regenerative cooling, atmosphere or vacuum. There's plenty of info about exhaust ...
8
votes
1answer
400 views

How can firing a Space Shuttle OMS engine below 21 km cause its nozzle to "collapse"?

This answer to Can the space shuttle use OMS engines during landing? says: No and quotes Section 3.7 of the Orbital Maneuvering System Workbook; OMS 21002 October 10, 2006, Final version, USA006500 ...
5
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1answer
2k views

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.
5
votes
1answer
453 views

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 ...
4
votes
1answer
403 views

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 ...
2
votes
2answers
295 views

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 ...
9
votes
1answer
489 views

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 ...
8
votes
1answer
331 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?
5
votes
1answer
830 views

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 ...
5
votes
2answers
327 views

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 ...
5
votes
2answers
343 views

What factors determine the altitude at which rocket exhaust plumes start blooming hugely?

The images below are from a much larger set of photos in Spaceflight Now's August 8, 2019 article Photos: Atlas 5 paints the sky with spectacular sunrise launch. They show several effects related to ...
4
votes
1answer
326 views

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? $\hskip 3.4 cm$...
4
votes
1answer
159 views

What were the stingiest and most generous vacuum nozzle? (records for the smallest and largest expansion ratios)

Vacuum nozzles are huge compared to their sea-level or atmospheric counterparts, as can be seen by comparing the first stage engines on an Electron or Falcon-9 to their second stages, where a big ...
3
votes
2answers
2k views

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 ...
2
votes
1answer
259 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?
2
votes
1answer
132 views

What expansion ratio is the best for mars surface level engines?

What expansion ratio is the best for mars surface level engines? For launches from Earth, first stage nozzles are much shorter than second stage nozzles because of Earth's high sea-level pressure. For ...
2
votes
2answers
662 views

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 ...
2
votes
0answers
82 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 ...
2
votes
1answer
458 views

Under-expanded nozzle at sea level - is it a problem?

I'm designing a solid rocket motor with a fixed pressure in the combustion chamber $p_{cc} = 70~bar$. When it comes to the choice of the right nozzle, I have to consider the proper expansion ratio, in ...
2
votes
0answers
133 views

Why nozzle extensions for ULA's Vulcan; why not make them this long in the first place?

This answer to What is the difference between the Vulcan 562 configuration and the Vulcan 5H2 ("Heavy") configuration? explains that the 2nd stage nozzles were modified by extending them, ...
1
vote
1answer
434 views

What is a typical sea-level engine nozzle/expansion ratio? What about vacuum engines?

On a sea-Level engine, what is the average nozzle ratio? What about an upper-stage vacuum engine?
1
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2answers
1k views

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?
1
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0answers
82 views

Need help finding a clean expression for exit velocity [duplicate]

I'm trying to calculate a engine burning LOX and ethanol (96%) and for that I am using both CEAgui, a GUI for NASA's CEA (Chemical Equilibrium with Applications) code Sutton's Rocket Propulsion ...