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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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 ...
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5 votes
0 answers
113 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 ...
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5 votes
1 answer
530 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 ...
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2 votes
2 answers
154 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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15 votes
5 answers
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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14 votes
4 answers
3k views

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 ...
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4 votes
4 answers
262 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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  • 1,117
0 votes
1 answer
360 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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-2 votes
1 answer
167 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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  • 1,117
2 votes
1 answer
144 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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  • 1,117
3 votes
2 answers
651 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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2 votes
0 answers
52 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 ...
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5 votes
2 answers
215 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 ...
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2 votes
1 answer
567 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 ...
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7 votes
2 answers
216 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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6 votes
0 answers
87 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 ...
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3 votes
1 answer
259 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, ...
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3 votes
1 answer
239 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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3 votes
0 answers
108 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 ...
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  • 101
6 votes
2 answers
869 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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1 vote
0 answers
84 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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1 vote
3 answers
885 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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  • 135
0 votes
1 answer
106 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 ...
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  • 3,422
6 votes
2 answers
192 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?
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  • 3,422
7 votes
3 answers
2k views

Why was the Delta Clipper cancelled?

The Delta Clipper (McDonnell Douglas DC-X) achieved vertical landing two decades before SpaceX's Falcon 9. And its cost was very low — only 60 million dollars. Why was such an awesome rocket cancelled?...
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  • 2,502
4 votes
2 answers
217 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 ...
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  • 652
2 votes
1 answer
133 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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  • 3,422
1 vote
0 answers
318 views

Can Chemical Engineer work on something related to space?

I am an undergraduate student (scientific section) living in Qatar. I have a big interest in astronomy and astrophysics and have participated in the IOAA (International Olympiad on Astronomy and ...
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2 votes
0 answers
133 views

Design of propellant tanks of a rocket [duplicate]

I understand that the propellants (e.g. LOX & LH2) are stored in a rocket tank which is pressurized by Helium or a neutral gas, so as to push the propellants towards the tank outlet, to the turbo-...
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  • 3,422
11 votes
3 answers
998 views

Why are spin-stabilized rockets stable?

Spinning rigid bodies are stable about their axes of smallest and largest moments of inertia. When there are energy dissipation modes, such as bending and propellant slosh, only the largest moment of ...
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2 votes
0 answers
77 views

Federal Limitations on Model Rocketry in India

I am hoping to find information on the rules regarding model rocket launches in India. How high can I fly? How heavy can a custom rocket be? Can I legally make and fly custom engines/motors?
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7 votes
1 answer
213 views

Does thrust depend on rocket chamber shape?

I mark with green part of rocket which produce forward thrust and with red backward thrust. integration of pressure around rocket walls gives total thrust,which always act in forward direction.. Does ...
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-1 votes
0 answers
54 views

Does thrust depends on rocket chamber shape? [duplicate]

i mark with green part of rocket which produce forward thrust and with red backward thrust. integration of pressure around rocket walls gives total thrust,which allways act in forward direction.. Does ...
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2 votes
2 answers
87 views

What stage of a Scout G-1 rocket enters orbit?

Last night I saw a Scout G-1 rocket body part called 1986-088B (according to COSPAR) with my binoculars. I researched a little and found that these rockets had 4 stages, called Algol, Castor, Antares ...
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2 votes
1 answer
133 views

Will the Mars 2020 rocket be visible in the night sky?

When a Space X rocket was launched towards the ISS this year, the rocket could be seen in the night sky in Europe. The information as to where and when to look in the sky was even easily available ...
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23 votes
2 answers
8k views

If rocket engines only need fuel and oxidizer, then why there are so many pipe lines on the engines?

If fuel and oxidizer are pumped by turbines to the combustion chamber, then why there are so many pipes around? It should only have a two-cylinder shaped turbine assembly. I doubt there are other ...
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7 votes
1 answer
258 views

Which are good resources to learn more about the components of a rocket engine?

A detailed and annotated image of a SpaceX raptor engine (found on a SpaceX website) illustrates that in addition to the major components (e.g. pumps, inlets, combustion chamber, nozzle), there are ...
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3 votes
0 answers
60 views

Why there are small holes just at the ending of RS-25 rocket engine? [duplicate]

I have seen these holes in many pictures and I can't understand what are these and why are they used?
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2 votes
2 answers
238 views

Best shape for Orion nuclear pulse-propelled ships?

I have been doing research on Project Orion. There was this big expensive canceled NASA program to build armored spaceships that had to be blasted into space by exploding nuclear charges underneath ...
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5 votes
0 answers
126 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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3 votes
3 answers
2k views

What (if anything) limits the efficiency of a rocket engine?

Humans have developed lots of rockets. I observe that in most cases to increase the payload capacity we just increase the amount of fuel. Is it not possible to exponentially increase the efficiency ...
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2 votes
0 answers
75 views

Full Flow Staged Combustion Benefits vs Closed Staged Combustion [duplicate]

I am aware that the RS-25 space shuttle engine was a closed staged combustion engine, and used two preburners (both fuel rich) to drive the turbines and pumps to pump the LOX and fuel into the ...
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  • 21
3 votes
2 answers
544 views

What is the maximum practical deltaV obtainable from a chemical rocket launched from earths surface?

What is the maximum practical deltaV obtainable from a chemical rocket launched from earths surface? Not an exact number as there are too many variables but an approximate maximum assuming a 10,000kg,...
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4 votes
1 answer
224 views

Do converging-diverging engine nozzles need to be bell-shaped?

Many rockets designed after the V2 but prior to Saturn V, do not show the typical "Bell" shaped diverging nozzle. Why is it so? Do they achieve supersonic speeds for the exhaust gases in any other way?...
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  • 3,422
1 vote
1 answer
119 views

Pump Power related queries

I know that pump power can be calculated using this formula $$P_p = \frac{\rho \ Q \ \Delta H \ g_0}{\mu_p}$$ Source: Rocket Propulsion Elements by Sutton 8th Ed. Equation 10-16, Chapter 10. Page ...
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27 votes
3 answers
4k views

Falcon 9 launch process - perception of launch speed

One of the things that drew attention from my local group of rocket-watchers with the Falcon 9/Crew Dragon launch is the perceived speed of the actual launch process. We have been conditioned for ...
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  • 379
10 votes
1 answer
857 views

why do under-expanded engines have less than ideal thrust?

I've been looking into rocket propulsion a bit and got stumped on something. I read that the thrust generated by an engine can be determined by the following: $$ F = \frac{w}{g}v_{e}+A_{e}(P_{e}-P_{a})...
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10 votes
2 answers
2k views

How was Demo-2's Falcon 9 booster different from any other F9?

According to The Sum Of All Knowledge, the Falcon 9 has only twice (including the 2016 ground fire destroying the payload) failed to put the primary payload in orbit. Thus, the May 30 2020 Demo-2 ...
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2 votes
1 answer
300 views

How much LOX is vented / wasted while loading?

We're all aware of the recently aborted SpaceX Demo-2 launch... While talking with friends we discussed the venting of LOX pre-launch. I presume that the reason for this venting is largely to achieve ...
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  • 123
4 votes
2 answers
378 views

single thrust vs. multiple thrust

Does using one 5000 pound thrust engine give the same amount of thrust as five 1000 pound thrust engines? I am asking in terms of effectiveness not efficiency. Do the two different configurations ...
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