Questions tagged [rockets]

Questions regarding the boosters or thrusters used to propel man-made objects. For rockets firing opposite the primaries, see [retrorockets]. See wiki for other related tags.

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Were there any launch vehicles with so heavily pronounced Plume Induced Flow Separation (PIFS), other than Saturn V?

This answer describes a very interesting phenomenon of Plume Induced Flow Separation on Saturn V vehicle. (Apollo-6 S68-29737 photo, courtesy NASA) This is, basically, when "fire" from ...
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What performance can be expected from chemical rockets under Venusian atmospheric conditions?

Is it feasible to use either solid or bipropellant liquid rocket engines to lift off from the surface of Venus? "Reference datum" air pressure on Venus is around 9.3 MPa; even on the top of, say, ...
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163 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.
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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 ...
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SpaceX Dragon Shape: Power Series, Ellipsoid, or Haack/Von Karman?

The SpaceX Dragon module has a round apex typical of power series, ellipsoid, and Haack/Von Karman shapes. I'm wondering which of these SpaceX actually used. References would be appreciated. My guess ...
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What are these wires on the side of the SLS core stage?

I was reading about the SLS core being moved for testing and I noticed something odd on the core stage. There's several lines on the stage, which in closer inspection are wires. It's not obvious what ...
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163 views

Are DUMBO, TIMBERWIND, and other high-thrust NTRs realistically going to deliver on promises of very high thrust/weight?

Nuclear thermal rockets (NTRs) are notable as the most mature technology (the second-most-mature is Project Orion) to provide both high thrust and higher specific impulse than chemical rockets. But "...
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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 ...
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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 ...
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417 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?
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Have any stages of rocket killed aquatic animals?

This question may seem off-topic but I am curious.Those rockets that aren't reusable let their stages fall and splash down on the ocean. Is there any news reported that they have killed some aquatic ...
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How much cheaper are pressure fed engines compared to other cycles (e.g. staged combustion, gas generator, electric pump-fed)?

It's well known that pressure fed engines are mechanically simpler, and therefore cheaper than pump-fed cycles (although pressure fed has worse performance). However, I haven't found any sources that ...
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101 views

Why does kerosene need inducer?

We see inducers before the main kerosene turbopump in engines such as F1 and RD180. Given the property of kerosene having extremely low vapor pressure (~0.007 bar around room temperature), is this ...
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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 ...
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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 ...
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333 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 ...
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83 views

What are the implications of North Korean black and white patterns on missiles?

Black and white patterns on rockets were originally intended as roll patterns. They helped as a visual back-up for acceleration sensors measuring the roll, as discussed in this previous question What ...
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Low-pressure pump-fed rocket engine?

I saw the above suggested in LEO on the Cheap. In P.130 it says: A compromise between high-performance/lightweight pump-fed vehicle designs and cost-optimized pressure-fed vehicles with heavier ...
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56 views

Is there any work in English that gives a systematic treatment of Soviet/Russian rocket engines?

There seems to be some piecemeal information online such as RussianSpaceWeb.com, and of course, Sutton's History of LPRE gives an anthropological treatment of Soviet/Russian rocket engine lineup ...
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136 views

Why is the relative axial position of oxidizer vs fuel tank inverted in the upper stages of most rockets?

In the first stages of most rockets, e.g. Atlas V, Delta IV and Falcon 9, the oxidizer tank is stacked on top of the fuel tank, with the usual explanation that such an arrangement gives the rocket a ...
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205 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, ...
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136 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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442 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). ...
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55 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?
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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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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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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 ...
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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 ...
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206 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 ...
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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 ...
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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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545 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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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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1answer
160 views

Design of starship fins

How much can the falling speed of starship approximately be reduced by the bellyflop fall with fins? Are we talking about numbers around 5% or 50% here? Wouldn't it make sense to put holes where the ...
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How to experimentally determine the degree of atomization of the propellants mixing in a fuel injector?

When validating a fuel injector design on a test stand using liquid water to simulate a liquid-liquid fuel injector(the one i'm working with currently is a pintle design but I suppose one could ...
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Rocket Engine - Actuator in Loop Simulations

For Actuator-In-Loop simulations, why are the rocket engine nozzles along with the thrust vector control assembly (including the actuators) kept inverted on a platform like in the attached image or as ...
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Can we re-fuel solid-core nuclear thermal rockets?

Most solid-core nuclear rocket designs seem to have a rather short fuel lifetime (and one that wastes most of the uranium or plutonium) due to the buildup of fission products (combined with the very ...
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232 views

Cost of launch unrelated to cost of building rocket

ULA CEO Tory Bruno said long time ago that only 1/2 cost of orbital launch is cost of building of rocket. SpaceX never denied this. F9R block 5 total cost of launch can be about 60-80 million per ...
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What's the most optimal method of motor attachment for Horizontal Static Fire Tests?

I'm a college student new to rocketry, and am working on the horizontal test structure for a static fire test of our motors. The max thrust for the booster motor is about 6000 pounds, and the ...
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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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155 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 ...
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How are the liquid propellant umbilical cord protected from the exhaust?

The launch pad umbilical cords supply propellant to the rocket, and will definitely have some remaining at the time of liftoff. I remember the Saturn V footage wherein a heavy protection door slams ...
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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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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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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 ...
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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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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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91 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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176 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?
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Is steam a good gas to use for a small RCS thruster on a small rocket?

Is steam a reasonable tradeoff from other hot/cryogenic gases in order to have safety and have it easily obtainable? Thanks