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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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RS-25 Component weight

I need to determine the weight for specific components of the RS-25 Rocket engine. Namely the combustion chamber and nozzle separate from all other engine components? I must have found hundreds of ...
Slartibartfast's user avatar
2 votes
0 answers
43 views

Nozzle contour estimation (Merlin 1D Vacuum)

I would like to run a fluid simulation of the diverging section of a Merlin 1D Vacuum engine. While most relevant parameters (such as expansion ratio, flow rate, and nozzle area) are readily available,...
FTT's user avatar
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1 vote
0 answers
118 views

Does an overexpanded nozzle behave like a suction cup?

It is generally said that, to obtain optimal specific impulse, a nozzle should be just the right size that the exhaust pressure is equal to the ambient pressure. Quoting this answer, a relevant ...
Charles Staats's user avatar
2 votes
0 answers
103 views

Help with designing nozzle geometry for compressed air thruster

I am designing a compressed air thruster with a conical nozzle geometry. The general design consists of a compressed air tank, pneumatic tubing, and then the actual chamber with the nozzle. The ...
Kyle's user avatar
  • 21
5 votes
1 answer
656 views

Why is the expansion ratio of the nozzle of the 2nd stage larger than the expansion ratio of the nozzle of the 1st stage of a rocket?

As an answer I have two statements, which statement is correct? If one or both are wrong, can you please provide me an explanation? Statement 1: The goal is to achieve maximum efficiency in thrust. ...
RocketEngineerStudent's user avatar
1 vote
0 answers
177 views

How to find the correct size and angle for a conical nozzle on a rocket engine? [closed]

So I need to know the equations for finding the size and angle for a conical nozzle. I am making a rocket engine and I decided the conical nozzle would be the easiest to build. The rocket is going to ...
Anish Kommireddy's user avatar
2 votes
1 answer
192 views

Is specific impulse and thrust maximum in vacuum or for exit pressure equals atmospheric pressure?

According to the thrust formulation of a rocket one can show, that maximum thrust is not delivered for pambient= 0 but for pambient=pnozzle_exit since then the momentum term is maximized. But then I ...
Kevin's user avatar
  • 29
3 votes
0 answers
116 views

How do ablatively cooled rocket engines compare to regeneratively cooled ones, in terms of mass?

Assuming equivalent thrust and single continuous burn duration, is there a figure that roughly tells the difference in mass between these two engines cooling methods? This question focuses on first ...
user avatar
4 votes
1 answer
137 views

Would it make sense to compress air around a bell nozzle during booster ascent?

Regarding boosters having one single liquid fuel engine, such as Delta 4 for example. Would some sort of annular aerodynamic device, attached to the skirt and placed around the bell nozzle, help ...
user avatar
0 votes
1 answer
77 views

Higher nozzle exit velocity generally means higher thrust right?

Higher nozzle exit velocity generally means higher thrust right? If that is the case, then a higher heat capacity could potentially lead to a higher exit velocity, thus higher thrust?
FalconHeavy321's user avatar
0 votes
1 answer
142 views

Calculate Thrust of Rocket Nozzle - Off Design

I have designed a nozzle for the following input parameters $p_{combustion}=p_c=200*10e5 Pa$ $T_{combustion}=T_c=2800 K$ $F=70 kN$ $\kappa=1,2$ $R = 330 J/kgK$ I assume that all my gas properties ...
Kevin's user avatar
  • 29
0 votes
0 answers
125 views

How to avoid big nozzle lengths in high altitude?

I am currently designing a serial staged rocket with 3 stages. The first stage brings me up to 10 km. When I do my calculations for the required expansion ratio and nozzle length (Rao Nozzle) for the ...
Lucas's user avatar
  • 37
2 votes
1 answer
192 views

Difference between Optimum Expansion Ratio and Maximum Thrust

when I look at the equation for thrust of a rocket: $$ F=\dot{m}*v_{exit}+(p_{exit}-p_{amb})*A_{exit} $$ In the book "Rocket Propulsion" from Sutton it says on page 33: In the vacuum of ...
Lucas's user avatar
  • 37
0 votes
1 answer
66 views

Choked Flow: Throat Radius should not change any more below critical pressure ratio?

I am trying to understand some calculations of a student colleague: The pressure inside the combustion chamber is 200 bar. This means, the critical pressure ratio should be p*/p0 with p0=101325 ...
Lucas's user avatar
  • 37
1 vote
1 answer
231 views

How to find the average ambient pressure during rocket ascent?

I am trying to find the average ambient pressure that my rocket will flight through during its ascent to then determine the most optimum conditions in my combustion chamber and nozzle. I have ...
stanisverylow's user avatar
3 votes
1 answer
357 views

What am I missing about rocket nozzle isentropic flow?

Playing a bit with Cpropep-Web, something looked wrong to me about how it models isentropic flow through a CD nozzle. I'm taking the RS-25 characteristics as an example. I ask for a frozen equilibrium ...
Florian Cabot's user avatar
9 votes
1 answer
620 views

What is the area of the SSME nozzle knowing only thrust at sea level and in vacuum?

Looking at the SSME Wikipedia RS-25 Space Shuttle Engines, the data shown that the thrust at sea level ($F_{sl}$) is 1.816*10$^6$ N, while the thrust in vacuum ($F_{vac}$) is 2.278*10$^6$ N. Knowing ...
Julio Gonzalez-Saenz's user avatar
2 votes
1 answer
234 views

Discrepancies in thrust chamber dimensions for RL10

I've recently been developing some automated scripts in Python for the purpose of calculating engine parameters. I've been using the RocketCEA interface library, which links to NASA's Chemical ...
ecfedele's user avatar
  • 527
6 votes
1 answer
766 views

What happens if the mass flow rate is increased continuously in a converging nozzle?

I recently studied about nozzles where I came to know that the maximum velocity one could attain using a converging nozzle is the sonic velocity at the exit of the converging nozzle. An further ...
Prasanna B's user avatar
1 vote
1 answer
212 views

Does thrust vectoring by a gimballed nozzle in rockets affect thrust/efficiency?

I was wondering if thrust vectoring via a maneuvering gimballed nozzle affected the thrust of a rocket. I've read a couple times that a gimballed rocket engine's thrust doesn't change while exhaust ...
Yourhelpismuchapprecciated's user avatar
2 votes
2 answers
197 views

Restartable Solid Rocket Motors Through Expanding Throats?

I recall seeing diagrams on a solid rocket motor that could "blow" itself out through suddenly expanding its nozzle, leading to the propellant no long burning or producing any thrust. First ...
itisyeetimetoday's user avatar
0 votes
0 answers
53 views

Analytical representations for thrust in underexpanded flow (P_e>P_a) [duplicate]

I am familiar with the ideal thrust equation: $F=\dot{m}U_e +(P_e-P_a)A_e$ When $P_a$ is greater than $P_e$, you have thrust losses, and the equation accounts for that. When $P_a=P_e$, you achieve ...
alexmesa's user avatar
5 votes
2 answers
2k views

Are nozzle plugs taken out before launch or are they ejected upon ignition?

Inspired by this question. For most orbital launch vehicles, do their engines have nozzle plugs installed and what happen to them at launch? Are they manually removed during the prelaunch/rollout or ...
WarpPrime's user avatar
  • 3,125
4 votes
1 answer
244 views

Discrepancy in local Mach behavior between CEA and other sources

I'm exploring some designs using the NASA CEA (Chemical Equilibrium with Applications) code and I ran into a discrepancy between CEA predicted values for local Mach number at the exit plane and values ...
ecfedele's user avatar
  • 527
3 votes
1 answer
245 views

Specific impulse of a rocket engine

Keeping other things (fuel, oxidizer, their ratio, mass flow rates, throat diameter, other hardware like pump, injector nozzles & impinging pattern etc.) same, if I changed only the geometry (...
Niranjan's user avatar
  • 3,758
3 votes
0 answers
107 views

Using a laval nozzle as supersonic inlet - what happens at throat? [closed]

I am wondering what will happen, if I use the laval-nozzle , which normaly accelerates a fluid the other way round: So what happens if I fly with my aircraft at Mach 2 and I collect all the air in my ...
Lucas's user avatar
  • 31
1 vote
1 answer
194 views

Designing of CD nozzle with respect to Mass flow rate of propellants

How do I calculate the flow rate of exhaust gases required at the throat of a CD nozzle, with given throat diameter of "D", so as to achieve a "Choked flow condition" (velocity of ...
Niranjan's user avatar
  • 3,758
0 votes
1 answer
141 views

Can Vacuum nozzles be used as cooling radiators in LEO?

Radiators are used for thermoregulation of spacecraft. https://www.academia.edu/934756/Thermal_Control_Handbook . Their effectiveness requires their surface be exposed to deep space, not an IR ...
Woody's user avatar
  • 22.1k
0 votes
1 answer
5k views

Calculating rocket nozzle throat area

I'm trying to calculate a rocket nozzle throat area, $A_t$. My propellant is KNDX. I am trying to do this according to the following equations, taken from this reference: where $P_t$ is and $T_t$ ...
Alatriste's user avatar
  • 117
3 votes
1 answer
196 views

What happens with thrust if I decrease the convergent divergent nozzle exit area?

I am new to rocket design and I have a couple of questions. If I have a convergent - divergent nozzle and I have a choked flow condition for the throat, what will happen a) with my exit pressure b) ...
Lucas's user avatar
  • 31
2 votes
1 answer
217 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 ...
Achillebckr's user avatar
3 votes
1 answer
505 views

Conversion of heat into electricity in rocket nozzles

Can we use advanced thermoelectric materials to reduce the temperature of nozzles by converting heat energy to electric energy and reducing the strain on the nozzle material and the coolant while ...
cntcod3's user avatar
  • 69
3 votes
1 answer
422 views

Sea-level nozzles

I understand that there are sea level-optimised and vacuum-optimised nozzles, but why optimise for sea level when the rocket doesn't spend much time there? I would expect the first stage nozzles to be ...
Paul Price's user avatar
5 votes
0 answers
156 views

Aerospike calculator software doesn't seem to altitude-compensate - am I misunderstanding aerospikes?

I'm using mvernacc's Aerospike Nozzle Design GUI, which is supposed to be able to design and predict the performance of aerospike rocket engines. The workings of the software are apparently based on ...
DodoDude700's user avatar
4 votes
1 answer
826 views

What were/are 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 ...
uhoh's user avatar
  • 149k
1 vote
1 answer
384 views

nozzle throat area calculation for choked flow

I am quite confused for my sugar propellant rocket nozzle. I have designed a CD nozzle by hit and trial method. It worked but produced so less amount of thrust .I have used 2.3 kg propellant which ...
Krishna Mishra's user avatar
10 votes
1 answer
622 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 ...
uhoh's user avatar
  • 149k
17 votes
3 answers
2k views

Is it always one nozzle per combustion chamber and one combustion chamber per nozzle?

When I read about engines like the RD-170 they might have a single turbopump feeding multiple combustion chambers, and each combustion chamber has its own nozzle. Is there, or would it be reasonable ...
Greg's user avatar
  • 4,287
0 votes
0 answers
79 views

Design a cold gas ACS nozzle

I have the total thrust required to be F=16.9 KN. I am using nitrogen gas, and the stored temperature in the nitrogen gas cylinder is 155 bars with a temperature of 325k. How would I design the nozzle ...
letsflybaby's user avatar
6 votes
3 answers
1k views

Aerospike with solid fuel

I was scrolling in youtube and I saw this awesome video and I think, if we put an aerospike nozzle in a sounding rocket,or even a small orbital rocket, as a first stage solid booster, this type of ...
Valentino Zaffrani's user avatar
3 votes
1 answer
227 views

Do pulse detonation rocket engines require any type of nozzle?

Rocket nozzles are used to convert slow moving gas under high pressure and temperature into hypersonic gas under approximately ambient pressure. From many videos of experimental Pulse Detonation ...
WOW 6EQUJ5's user avatar
  • 2,321
1 vote
0 answers
122 views

Which engine has the highest nozzle wall temperature? [closed]

From all the rocket engines that were used in flight, which one has the highest nozzle wall temperature? The nozzle wall is not heated uniformly. But there are regions where they reach max temperature....
Joe Jobs's user avatar
  • 2,650
16 votes
2 answers
4k 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 ...
Camille Goudeseune's user avatar
0 votes
1 answer
246 views

What if we have a DC nozzle instead of a CD nozzle?

My understanding is that the exhaust gas gains velocity as its heat converts to kinetic energy, regardless of the geometry of the nozzle, and the reason we have a convergent-divergent (CD) nozzle is ...
Xi Liu's user avatar
  • 229
1 vote
1 answer
119 views

I'm having a problem with the Throat Area formula derivation

I came upon this when reading "Introduction to Rocket Science and Engineering, he said "by differentiating" , my question is: differentiate with respect to what? and how do you get such ...
Sadok Smine's user avatar
5 votes
1 answer
787 views

Contracting rocket engine nozzles

The efficiency of rocket engine nozzles depends greatly on their expansion ratio an how well the ambient pressure matches the rocket nozzles exit pressure. An optimal expansion ratio means that there ...
publicdomain's user avatar
  • 1,222
3 votes
1 answer
148 views

At which pressure does a liquid fueled rocket start producing supersonic flow?

In a compressed-tank LOX+ethanol (or similar liquid fuel) rocket: How much should the tank or combustion chamber pressure (which should be the same) be to have a significant exhaust velocity increase ...
Sartem Cacartem's user avatar
5 votes
1 answer
1k views

Can exit pressure of nozzle be less than atmospheric pressure?

This is kinda dumb question .I got 5psi pressure at outlet of the nozzle from open motor software. Is that possible because its less than atmospheric pressure 14.7 psi? Am i missing out something?
Auberron's user avatar
  • 1,506
3 votes
0 answers
212 views

Why use 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, ...
uhoh's user avatar
  • 149k
1 vote
0 answers
86 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 ...
StarshipGood's user avatar