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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3
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1answer
65 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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4answers
1k views

Using of the rocket propellant for engine cooling

Why does liquid space propellant make a good engine coolant? I was researching the regeneratively cooled nozzle and combustion chamber on the Merlin 1D when I found this out. I do know that the pipes ...
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2answers
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Can we just throw a satellite in to mars orbit with a very high spin?

I am thinking about this scenario of throwing a satellite to Mars orbit with a high spin, Can we just throw that? one hypothesis can be that high-frequency spinning generates apparent gravity so it ...
7
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1answer
196 views

Why do some rockets have closed boattails around the engines and others do not?

During launch and landing, dust, dirt and debris may be stirred up. For non-gimbaling engines like the vac Raptors on Starship, can't the engine fairing/boattail be closed? I imagine titanium sheet ...
5
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0answers
88 views

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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1answer
1k views

What happens to where umbilical lines are connected when a rocket lifts off?

I've read about umbilical lines in rockets but I don't understand what happens with the places where each umbilical is connected to the rocket once it lifts off. I guess they are sealed in some way in ...
16
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1answer
2k views

Why is the tip of this Russian ICBM folding/closing during launch?

This question refers to the page on which a YouTube video Soviet Missile SS-18 Satan / Most Powerful Rocket is shown. Screenshots below are from circa 01:10 for ...
2
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1answer
119 views

How do we maintain the RPM of turbo pumps in liquid rocket engine?

How do we maintain the RPM of turbo pumps in liquid rocket engine? And how do we control it? And in the case of electric pump fed engine (like Rocket Labs's Rutherford engine) is easy but how we do it ...
3
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1answer
101 views

Is the Ceres-1 the first Chinese rocket that was given an official Romanized name?

The news feed in the The Pod Bay links to NASA Spacelfight's 2020-11-08 news item Introducing China’s new commercial rocket, Ceres-1. China’s latest commercial rocket, the Ceres-1 (Gushenxing-1) ...
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1answer
1k views

Why is butane never used in rockets as fuel?

From what I know, it seems good, so why does no one use butane as a rocket fuel?
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1answer
107 views

Let's say I build an orbit-capable launch vehicle, what tests/certifications would the LV have to acquire to be allowed to launch payloads into orbit?

For the purpose of the question, let's assume said launch vehicle is 100% identical to Electron. What sort of tests/certifications would I have to send the rocket through in order to make it legal to ...
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1answer
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Merlin 1-D Vacuum - Side Exhaust Noted in Flight Videos

During the Falcon 9 second stage firing of the Merlin 1D Vac engine, the video shows an exhaust plume ejecting from near the top of the nozzle bell, and canted outward (say 10 degrees) from the bell. ...
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3answers
2k views

Which theoretical propulsion system has the highest specific impulse?

I know that NERVA physically demonstrated 811 seconds, and the theoretical range for Orion was around 10,000. After stipulating that we can't really know for sure until it's built, given plausible ...
2
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1answer
51 views

What is the effect of poorly choosing L* in combustion chamber design?

I am a member of a university rocketry club and we are in the process of designing a liquid rocket engine. One of the previous propulsion leads did the primary conceptual design of this engine in RPA. ...
1
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1answer
70 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 ...
6
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2answers
865 views

How do launch vehicles measure speed during lift off and ascent?

What kind of instruments does a rocket use to track its trajectory and velocity during ascent? Do they use pitot tubes or barometric sensors? What exactly are the instruments used?
3
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2answers
92 views

Isentropic flow through a rocket nozzle and constant mass flow rate

The definition of isentropic flow is that the flow is both adiabatic (no heat is transferred into or out of it) and reversible (energy is conserved in it). I am wondering why the flow through a rocket ...
2
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1answer
67 views

Why maintain nominal engine inlet mixture ratio for a gas generator engine?

I was reading up on gas generator cycles and came across the following paragraph talking about fuel or oxidizer rich gas generators and the different mixture ratios for the main combustion chamber ...
6
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1answer
85 views

Electron rocket holding & releasing mechanism

Launch vehicles generally include a holding & releasing mechanism so that it will not leave the ground until proper engine function is confirmed and stable and sufficient thrust is achieved. These ...
12
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2answers
2k views

Is there such a thing as a “rocket license” in the US?

I heard in a video that a 15 year old got their rocket license before getting driving license. The video does not explain further; but what I'd like to know is: *In the US, is there any such a thing ...
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0answers
30 views

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 ...
2
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1answer
135 views

Flight characteristics of a three-passenger rocket with a range of up to 500 miles (800 km)?

If I could bring two of my best friends to a spaceport and take a rapid trip to a city hundreds of kilometers away (think half an hour to cross a continent), what would would be the vehicle's flight ...
4
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1answer
135 views

Do lower pressure pressure-fed rockets get more Delta-V?

I was playing around with the math for getting a pressure-fed rocket to orbit and came across something that I haven't seen addressed anywhere. In a pressure-fed rocket, the chamber pressure of the ...
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61 views

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 ...
5
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1answer
316 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 ...
5
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0answers
80 views

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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2answers
132 views

Trying to make a program to calculate (liquid) engine size. Can you please help me check for any problems?

So as the title says I am trying to write code to calculate engine size and some other parameters. For the equations, I used mostly : Sutton's Rocket Propulsion Elements 8th Edition, and for the ...
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5answers
4k views

Did anyone ever launch a rocket, filmed by another rocket in mid air?

I recently analyzed some SpaceX launch footage (a Starlink deployment on September 3). I noticed a switch in camera perspective at T+00:02:20: from cameras on the ground to those attached to the ...
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4answers
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Do the SpaceX Falcon-9 rockets use foam insulation similar to the Space Shuttle? Is it still a potential problem?

The Space Shuttle used polyurethane and polyisocyanurate foams for insulation. A chunk of foam breaking off during launch resulted in the Space Shuttle Columbia disaster. Do all chemically-fueled ...
4
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4answers
178 views

Alternative to GPS navigation for vertical landing, especially on other planets

Is the GPS data reliable or meaningful only on Earth or below the geo-stationary Earth orbit? For GPS navigation, does a rocket has to fly below the geo-stationary orbit? If GEO is a physical ...
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1answer
126 views

How much anti-matter is needed for an anti-matter propelled rocket to reach $P$ % ($P\lt{100}$) of the speed of light (c)?

I think this is a tough one. Imagine a rocket is produced which is propelled by a matter-anti-matter device. Its sole purpose is to reach high velocity. Which means the mass can be kept low, say $m$ ...
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1answer
145 views

Dispose Earth's nuclear wastes towards the sun [duplicate]

If rockets are reliable, can we throw our nuclear wastes towards the sun? The sun's gravity and it's internal energy will do the rest.
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1answer
111 views

Why not bring a rocket to idle velocity for less violent and safer re-entry? [duplicate]

Since kinetic energy have to be converted into heat during re-entry, the re-entry into the earth's atmosphere seems very violent. Why most rockets or crew re-entry modules plunge into the earth's ...
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2answers
222 views

How much more cost efficent are SRB's over the main engine?

Why use SRBs instead of a simpler rocket design that dispenses with SRB's and instead has a bigger main engine? The Saturn V escaped earth's gravity just fine without boosters. Since then though SRBs ...
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0answers
48 views

Roll Maneuver in SpaceX Demo-2 Launch?

I couldn't see a roll maneuver early in the launch of the demo-2 mission, and this left me wondering if SpaceX skipped the maneuver. Would they do the pitchover without roll? Also, I've noticed in one ...
5
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1answer
79 views

Source of Gregorek's popular drag equation in ESTES TR-11?

In the early 1970s, Gerald Gregorek wrote a technical note on drag for ESTES (maker of model rockets and parts from what I gather). The note is still very popular in the model rocket community, and it ...
2
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1answer
153 views

How does a rocket go from gravity turn to orbit?

A rocket launch normally begins with a roll to align with the orbital plane and a pitch to allow gravity to gradually torque the rocket down as it climbs. The combined roll and pitchover maneuver last ...
5
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0answers
84 views

Did any rockets have 5- or 7-fold symmetry?

Have any rockets ever been made with fivefold or sevenfold symmetry? Five or seven (or larger prime numbers, or multiples thereof) identical engines or boosters equally spaced around the center. (...
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0answers
69 views

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 ...
3
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1answer
126 views

What is the difference between the Vulcan 562 configuration and the Vulcan 5H2 (“Heavy”) configuration?

I was looking up some information about ULA's Vulcan rocket, and noticed something odd. There are two configurations, Vulcan 5H2 and 562 that have the same number of boosters, the same size of tanks, ...
3
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1answer
117 views

I don't know where to start with the calculations - rocket engine

Last year I stumbled upon the "How to design, build and test a rocket engine" pdf and since then I have been intrigued by making one (or at least calculating it). So I've been doing some ...
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0answers
58 views

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 ...
5
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2answers
541 views

How does spin stabilization intuitively work?

I am not very familiar with physics or rocketry and I am having a lot of difficulty grasping why spinning a rocket or satellite stabilizes it. Most sources I have looked at have said either that it ...
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0answers
77 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 ...
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3answers
797 views

Getting back from the Moon

This link describes the way back from the Moon surface to the orbiting spacecraft. But how could that spacecraft get back to the Earth? It is a long journey. How much rocket fuel would be needed, in ...
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1answer
81 views

Efficiency of rocket stages and converging/diverging nozzle

It is a fact (to the best of my knowledge) that for optimum thrust from a rocket engine, one of the most important factor is the design of its converging/diverging Nozzle - the diverging cone to be ...
6
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2answers
172 views

Did rockets use turbopumps prior to the V-2?

Did the liquid propellant rockets before V-2 use turbopumps or were their fuel tanks pressurized with gas? Or perhaps were their engines gravity-fed?
6
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3answers
2k views

Why was the Delta Clipper cancelled?

Delta Clipper (McDonnell Douglas DC-X) achieved vertical landing two decades before Falcon 9. And its cost was very small - 60 million dollars. Why was such an awesome Rocket cancelled? How is NASA ...
3
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2answers
129 views

how does the open expander cycle seperate the fuel for the pump and combustion chamber

I'm designing a single open cycle expander rocket engine using propane. However, I've been unable to find out whether or not the fuel is split into the turbine and combustion chamber before or after ...
2
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1answer
90 views

Rocket staging by use of strap on Boosters

Will it be advantageous to have multiple (say-3) stages of a rocket, arranged in a "strap-on" type SRBs' assembly, geometrically well distributed around the circumference w.r.t. their ...

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