Questions tagged [rockets]

Questions regarding the boosters or thrusters used to propel man-made objects.

73 questions with no upvoted or accepted answers
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8
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439 views

Why isn't stainless steel used for rocket engines?

Most people have probably heard by now that Elon is changing Starship to a complete stainless steel build. Anyways, it got me thinking, why isn't stainless steel ever used for rocket engines (nozzle, ...
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285 views

Why is SpaceX's Raptor's design so simple in comparison to SSME?

What is especially striking to me is how simple Raptor is in configuration compared to SSME. The Raptor doesn't have an LP fuel or oxygen pump. What's even more surprising, if we are to compare the ...
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203 views

Convective heat transfer on rocket during ascent

I'm looking for a way to (very) roughly estimate the convective heat transfer onto a rocket hull during atmospheric ascent (ideally through different planetary atmospheres). While I'm comfortable with ...
6
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140 views

Why aren't injector pumps used in rockets?

Is there something that makes injectors unsuitable as oxidizer pumps? Seems to me that rockets would benefit significantly from a pump with no moving parts that runs off its own exhaust.
6
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2k views

Propellant mass calculation

I have been given the following problem: To solve it I used the formulas: $v_e = I_{sp}.g_0$ $M_{propellant} = (e^{\Delta_v/v_e} - 1).M_{final}$ And I assumed that the apogee kick manoeuvre was ...
6
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429 views

What would be the range safety for vertically landing over land rockets?

sideFrom the Wikipedia article on range safety: Rockets are usually launched into a space above the launch range called the launch corridor. If rocket engines fail while the rocket flies inside ...
6
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1answer
401 views

How does the flight trajectory of a GEO vs LEO mission vary for a Falcon 9 first stage?

How does the trajectory vary between the two types of missions? Specifically, how does the speed and velocity vary for the booster for a Falcon 9 mission?
5
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118 views

What is the difference between “Air-augmented rocket propulsion” and “integral rocket-ramjet propulsion”?

While going through the topic called "Combinations of Ducted Jet Engines and Rocket Engines" in Chapter 1 of Sutton & Biblarz's Rocket Propulsion Elements, 9th Ed I found the section below. Line ...
5
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77 views

Russian Soyuz MS-09 Launch - back and forth rotation of the second stage (along the length axis). Precession?

In the ISS Expedition 56-57 Launch of Russian Soyuz MS-09, in the first view from the external camera at around 3:30, an obvious back and forth rotation (along the length axis) of the rocket can be ...
5
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0answers
1k views

Potential improvement to BFR or New Glenn if equipped with aerospike exhaust on their engines?

Aerospikes basically tackle the issue of the variability in required expansion ratio for a rocket engine to be efficient at a given altitude. A recent example though mired in legal issues is a small ...
5
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321 views

Are there any benefits on Venus compared to Earth with respect to reusing launch vehicles?

My assumptions around building up infrastructure for dealing with space launches from Venus assumes colonization based on the principles outlined by Geoffrey A. Landis of NASA in paper Colonization of ...
4
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73 views

Books on Vertical-Landing Vertical-Takeoff (VTVL) of Rockets? or Rocket Design in General?

I am working on a rocket control system design and I am trying to understand the the fundamental principles and concepts to design an efficient controller for recovering and landing the rocket, ...
4
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1answer
235 views

how reusable are electric pump fed rocket engines like Rutherford Engines of Electron rocket?

In electric pump fed rocket engines, propellants are pumped by two electric motors. So there is just one combustion chamber and that is the main combustion chamber. I guess electric pumps are fairly ...
4
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54 views

How do international students attend the SA Cup sounding rocket competition?

How do the international students carry the rocket along with propellants to this competition, if Airport Authority does not allow flammable substances?
4
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60 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 - $3000 K$ ...
4
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75 views

How much would mass-production impact the cost of solid-fuel rockets?

Let's imagine that, for some arbitrary reason, solid-fuel rocket stages were needed and built en masse in factories, like planes or even like cars. How much would it drive down the cost of an ...
4
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79 views

Marman vs collet seperation mechanism

The Marman and the Collet mechanisms are used for stage separation in rockets and launch vehicles. Which of these is most efficient, cost wise, weight wise and ease of usability wise? Which of the ...
4
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171 views

What would be the implications of high-altitude or catapult launch for orbital rocket?

There are lots of questions on here which ask "Why aren't rockets launched from railguns/mountains/balloons/etc." and lots of nice answers mainly dealing with the practical difficulties of doing so, ...
4
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282 views

The Shape of a Rocket

What is the shape of a rocket? My English teacher has challenged me with that question and I am not sure of the answer. My friends suggest 'polygon' but I believe the answer is a little more ...
4
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184 views

From a strictly engineering standpoint, would Venturestar have worked as an SSTO?

In looking at the questions here and here, I'm wondering - was the VentureStar platform doomed from the start (in ways nobody could foresee), or was it only the cooling problems with aerospike engines ...
4
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156 views

Mathematical reasoning behind pe=pa leading to maximum thrust

I've been looking at both the thrust and thrust coefficient equations (below) and I understand that they will be optimum in a vacuum when $P_a=0$. But, I see in textbooks that $p_e=p_a$ corresponds to ...
4
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186 views

What is the minimum melting point a material need to have in order for it to be used for the rocket chamber and nozzle?

I know the rocket temperature can go up to 3500 degree Celsius especially at the combustion chamber where it is the hottest. However I know there are cooling measures to cool the surface of the ...
4
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154 views

Is the variety in the Delta rocket family the result of an artisanal rocket industry?

Between the years of 1980 and 1990 the McDonnell Douglas company supplied at least 10 different variants of the Delta rocket family. Some of these were considered to be Delta rockets while some were ...
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366 views

Deriving the thrust of a rocket

I understand the the thrust of a rocket is given by $$F_x = M_e V_e - M_i V_i + (P_e - P_i) A_e$$ However when I try to derive it myself using Reynold's transport theorem I get the following: ...
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1k views

How is the process of launching a rocket mathematically modeled up front?

What I am looking for is an example where real persons in the real world really need to mathematically model a situation before they need to calculate the average and instantaneous rate of change. I ...
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65 views

What is the physics behind a rocket landing on a celestial body with an atmosphere?

I would like to know the different physics concept I would need to land a rocket being in orbit. I know the timing is important to leave it, how can one find this out ? Then how to compute the ...
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117 views

What is holding SLS back from launching?

I'm kind of confused on this point SLS has engines, a tank, side rocket boosters, a capsule, and seemingly all of the pieces. What is the major technical issue right now that is keeping SLS from ...
3
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69 views

Why are hexa airfoils used on rockets despite having more drag that diamond airfoils?

I was doing a study on airfoils shape for a rocket. I tested the diamond and the hexagonal airfoil with Missile DatCom, RasAero and the Shock Expansion theory and from my results it seems like the ...
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161 views

Falcon 9 Landing Speed

I wanted to know what the fastest speed is that a Falcon 9 can land at and thus the max force the landing legs can withstand. I assumed the mass when landed is 26,000 kg (I once heard that somewhere). ...
3
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102 views

Problems with shutting off “torch igniter” during the operation of combustion chamber

With reference to the presentation pp 76, where SSME's Augmented Spark Igniter is said to have their flame "On" even after the main combustion chamber ignition, is to prevent the blowback from the ...
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84 views

Maturity of interplanetary rockets technology with known fuel supply is close?

Considerably, the scale of current jet propulsion rocket technology to leave Earth is closely connected to the target delivery mass, mission goal and the required fuel quantity to lift and deliver ...
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80 views

Reliability of self pressurization of propellant tanks for liquid engines

In a cryogenic propellant tank, the liquid always continuously changes into gas which pressurizes the tank. To pressurize the tank more we can run the liquid through the pipes along the outer wall and ...
3
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1answer
99 views

Pressurization line (Helium to LOX tank line) chilling while pressurizing LOX tank

I have read that in rockets and launch vehicles Helium is used for the pressurization of propellant tanks. What temperature Helium is stored at? If Helium is stored at room temperature then while ...
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260 views

What is meant by chamber pressure in rocket engines?

Is "chamber pressure" the pressure at the tip of the injector, or the pressure before combustion inside the chamber, or the pressure after combustion inside the chamber?
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123 views

Do rocket labs store propellants at higher pressure than the other rockets?

It is known that the Rutherford engines run on an electric pump-fed cycle. There must be a trade-off between the tank pressure of the electron rocket and battery capacity, for batteries are dead ...
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46 views

Why GSLV uses different stage seperation mechanism for their different varients

Why GSLV mk II is using Marman mechanism for stage separation but GSLV mk III is using Collet mechanism for stage separation?
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79 views

How is supersonic rocket exhaust able to match sea-level pressures?

I understand that the diverging portion of a rocket nozzle speeds up the flow and also expands it, in order to best match ambient pressure outside. However, doesn't higher speed flow lower the ...
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150 views

What are the maintenance benefits of SABRE engine technology for SSTO launchers?

What are the maintenance benefits of the SABRE engine over all the other engines being considered for the propulsion concepts for SSTO Reusable launchers?
2
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1answer
95 views

What kind of methane-fueled rocket engines exist?

I have heard of methane being a strong contender for Mars and beyond. Methane is a cryogenic fuel and is said to have a high specific impulse, and work with closed- and open-expander cycles. I have ...
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0answers
47 views

What is the minimal distance of clearance in the direction of flight path for a rocket?

Usually the rocket launch sites are placed on a coast or a place where there's basically no civilian buildings in the direction of flight path. Is there a standard/regulation on the minimal ...
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0answers
31 views

How to create a new reactant Ammonium Dinitramide NH4[N(NO2)] in NASA CEA?

Ammonium Dinitramide(ADN) is a compound used as a green propellant for spacecraft propulsion applications. ADN-blends like LMP103S and FLP-106 are currently under development. However, performing a ...
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0answers
93 views

Payload fairing separation- Event based or time based?

Refer the answer for this question How strong and "hot" is the wind on the payload after the fairing is deployed at ~110km? It is clear that the fairings are separated when the free ...
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43 views

Conditions and sensors that can be used for parachute deployment?

I'm looking for an explanation on ideal conditions/considered factors when a parachute is deployed (particularly in large competition rockets). Also what sensors should be used to measure these ...
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0answers
37 views

Effect of the location of igniter in starting liquid rocket engine

What will be the effect of off axis igniter, say a Spark igniter has to be used along with a pintle? Will the igniter being off axis have any effect on engine start? Also, will an off-center igniter ...
2
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0answers
58 views

How to make a orbital launch tube work?

Normal rockets would not work in a pressurized tube, but could a stage be made for the diagonal launch tube to save fuel and weight? Can the bottom stage be nuclear powered? Unlike the piston launch ...
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0answers
61 views

Is it feasible to take liquid Helium in a Pressure Fed System?

Can liquid Helium be flowed through a heat exhanger to increase its temperature and pressure which will further pressurize fuel-oxidizer tanks.
2
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0answers
184 views

Exhaust plume length variation across different rocket types

In rockets we see exhaust plume smaller and bigger. I know length has some relation with the fuel mixture ratio (not confident about it). How to calculate, or at least understand, the variation in ...
2
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0answers
102 views

Which solid fuel is optimal for light rocket?

I am in search of comparatively cheap and powerful enough solid fuel. I've found rocket candy, but is it enough to reach 1km altitude? (My aim is a 2 metre high rocket with 0.5kg of payload.)
2
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0answers
57 views

Building a Drag model for rocket optimization

I need to build a drag model for my rocket optimization program and I stumbled upon by the following formula: $CD = CD_c(M)$, $K_n < K_{nc}$, $CD = CD_{fm}$, $K_n > K_{nf}$, $CD = CD_c +(CD_{...
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0answers
70 views

How can the delta-V be calculated depending on the launch altitude above sea level?

If we assume that we have a given launcher that is able to produce a $\Delta v$ of 10km/s at sea level takeoff, and is able to reach an LEO of 200km above sea level, what LEO altitude would that ...