Questions tagged [efficiency]
The efficiency tag has no usage guidance.
21
questions
1
vote
0
answers
63
views
Is using a variable Isp (constant power & acceleration) more efficient than a constant Isp when launching?
So after I wrote a particularly poorly received answer about variable specific impulse, based on discussion I read here, I realise I may have misinterpreted what was being discussed in that thread. ...
11
votes
1
answer
2k
views
What's the typical temperature of a reactor core in a nuclear thermal rocket?
I am curious of the typical temperature of a nuclear fission reactor in a NTR and I heard that increasing temperature could increase Isp but couldn't find any useful data online. Please provide viable ...
- 121
1
vote
1
answer
171
views
What is the point of having a central rocket engine when it receives performance losses?
Recently I asked this question about center engine performance and received an excellent answer from @OrganicMarble. The first sentence of the answer is
If anything, the flow field interactions hurt ...
- 3,055
5
votes
2
answers
2k
views
What is wrong with hydrazine as a monopropellant?
While answering a question about if N2O was a practical monopropellant, I found that hydrazine was considerably more efficient. So, why do people want to replace it with N2O, if hydrazine is more ...
4
votes
2
answers
365
views
How to compute each of these link budget terms?
The terms in Equation are all in decibels (dB), which is logarithmically scaled. In Equation, $P_{rx}$ is the received peak power, $P_{tx}$ is the transmitted peak power, $G_{tx}$ is the transmitter ...
- 115
40
votes
6
answers
8k
views
How much has fuel efficiency increased in rockets since the Apollo missions?
I have been talking with a friend of mine and the subject turned to modern rockets versus Apollo era rockets and fuel efficiency.
My friend stated that today’s rockets use half the fuel of the rockets ...
- 501
3
votes
1
answer
561
views
ISP losses associated with exhaust vane TVC
What is the impact of exhaust vanes, such as those in the A4 and Redstone rockets, on exhaust velocity and overall ISP? As well as this, what is the relationship between ISP losses and the width of ...
- 792
2
votes
2
answers
116
views
Efficiency in Space Capsule Docking Process
I'm watching the first operational Crew Dragon Capsule proceed through the regimented, and VERY careful International Space Station (ISS) docking process, which was turned on after pausing another ...
- 545
3
votes
2
answers
926
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 ...
- 817
2
votes
2
answers
299
views
Is it more efficient to burn all needed fuel in an Oberth manoeuvre at once or burn a fraction of the fuel for each orbit?
I was looking into Parker Solar Probes trajectory and was wondering what would be the most optimal way to utilize a retrograde thrust at perihelion to reduce the number of needed gravity assists. I ...
- 173
12
votes
2
answers
19k
views
Is the concept of the Epstein Drive based on actual theorized scientific research which is considered plausable?
I've always found it interesting when we see real life taking its cues from fictional arts, especially when it comes to Science Fiction technology. There are plenty of examples of classic books, TV ...
- 545
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 ...
- 69
4
votes
1
answer
312
views
Disadvantage of interstage trusses on Soyuz launch vehicle?
Brian Tompsett gave a detailed explanation of the advantages of the trussing in his answer to the question Why do the Russians use these fence-like interstage fairings?
The gap between Stage II and ...
- 6,837
2
votes
1
answer
281
views
Does "Air Launch to Orbit" makes the best use of Earth's Rotation?
Usually, all artificial satellites are launched in the prograde direction, since this minimizes the amount of propellant required to reach orbit by taking advantage of the Earth's rotation. Further, ...
- 3,156
5
votes
2
answers
430
views
Launch capabilities of GSLV Mark III
What are the parameters of determining the launch capabilities of a rocket? Also, How does ISRO's GSLV Mark III fare against rockets like N-1, Proton, R-7 etc?
- 193
0
votes
1
answer
162
views
Coupling satellites already in orbit reduce drag and debris?
How would 2 or more satellites be joined to reduce atmospheric drag? Could a 3rd satellite tow and join 2 or more satellites that are in similar orbits to prevent Kessler syndrome?
At the very least ...
- 1
-2
votes
3
answers
321
views
Can more thrust come from launching parallel to water?
Would having the exhaust of a rocket or air breathing engine in an early stage in close proximity to water on a horizontal launch provide more thrust?
Could a rocket launch off water horizontally in ...
- 1
0
votes
1
answer
106
views
What types of engines are able to go from Earth orbit to Martian orbit? [closed]
What engine is the most efficient in fuel and/or time to go from Earth orbit to Mars orbit and back again that are not capable of launching from the ground?
- 1
1
vote
0
answers
204
views
Orbit to Orbit Transport Stage
Would it be faster or cheaper to have a lander, SSTO, and/or SpaceX Mars rocket to rendezvous connect with a more efficient engine or "transport stage" or another lander, SSTO?
When the spacecraft ...
- 1
9
votes
0
answers
164
views
What rocket uses the largest percentage of Fuel/Oxidizer before liftoff?
inspired by this question: How much propellant is used up until liftoff?
which asks how much propellant (fuel/oxidizer) a typical rocket uses before liftoff. What has been or is the most non-typical ...
- 317
16
votes
1
answer
1k
views
How much propellant is used up until liftoff?
How much of the total propellant mass (fuel+oxidizer) of the first stage/boosters is usually burnt between ignition and liftoff?
- 5,385