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Questions tagged [fuel]

Questions about rocket oxidizer, propellant, reactive mass, or other fuels used in spacecraft or rockets.

6
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1answer
148 views

What temperature difference do the injectors in a cryo engine experience?

A quick follow-up to Does ISRO's Cryogenic Upper Stage have restart capability? What temperature difference do the injectors in a cryo engine experience between the propellant tank, and the ...
8
votes
2answers
611 views

Proportions of a reentering spacecraft as compared to fuel mass

Call this a thought experiment. Spacecraft to Earth orbit and beyond are traditionally launched by means of one or more rocket engines. The fundamental principle is that a rocket moves by expelling ...
16
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2answers
2k views

How are fuel tanks filled with cryogenic hydrogen?

Cryogenic hydrogen can react with the atmospheric Oxygen to produce an explosion: as well as being cold enough to liquefy (and possibly solidify) atmospheric oxygen, which can be an explosion ...
10
votes
1answer
478 views

How are fuel leaks discovered on a rocket?

Most are aware of the fact that the launch of GSLV has been aborted due to a fuel leakage, but how was the cryogenic fuel leak discovered? I'm not interested in this case only, but in general. What ...
11
votes
1answer
1k views

What is this red gas at the exhaust of the Long March 3B rocket during liftoff?

While watching today's live stream of the launch of the China National Space Administration (CNSA) Long March 3B rocket carrying Chang'e 3 lunar exploration probe and the Yutu rover to the Moon, @...
12
votes
2answers
939 views

Which currently operational orbital launch vehicle achieves highest system-specific impulse?

I'm primarily looking for comparison of currently operational orbital launch vehicles by system-specific impulse, or Issp, and to get a fair impression of achievable rocket propellant performance and ...
13
votes
1answer
1k views

What is a typical energy demand and carbon footprint of a space launch?

How much greenhouse gases are released per kg launched into space, what other energy is needed? For the scope of this question, let's ignore the embedded energy in all the machinery and just look at ...
14
votes
1answer
2k views

How long is it feasible to store cryogenic fuels?

Working with liquid nitrogen all day, I am constantly bothered by their boiling away, forcing me to go get more from the storage dewar. Likewise should be the case with any cryogen, e.g. LH2 and LOX ...
7
votes
1answer
583 views

Approximately how much fuel will ISRO Mars Orbiter have available when it enter Mars' orbit?

मंगलयान (Maṅgalayāna) is due to launch on November 05, 2013 AD of the Gregorian Calendar at 1436H (GMT+0530). Wikipedia writes to say The November 2013 launch will place the Mars Orbiter Mission ...
14
votes
2answers
1k views

How was reserve fuel calculated for the Apollo missions?

A quick follow-up to How much fuel was used for a Space Shuttle launch? My memory is a little foggy; I seem to recall reading the Apollo 11 mission commander depleted his reserve fuel landing Eagle. ...
15
votes
1answer
53k views

How much fuel was used for a Space Shuttle launch?

Many of us have watched the launch of a Space Shuttle space ship, I think: a giant red rocket, some smaller, and the way smaller space ship on the red one. It reaches Mach 23 to be able to leave ...
11
votes
2answers
975 views

Nuclear thermal rocket specific impulse calculation uses 1 amu, is that wrong?

Following the parameters in the Wikipedia nuclear thermal rocket article, it seems to paint somewhat of a shaky world view. Consider these quotes: Current (2010) 25,000 pound-thrust reference ...
30
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3answers
4k views

Why do the exhaust flames from cryogenic stage engines appear to be separated from the nozzle?

Why do the exhaust flames from cryogenic stage engines appear to be separated from the nozzle?
6
votes
2answers
537 views

What are the deal-breakers with a preheated Hydrogen gas tank orbital rocket?

Consider this thought process: In selecting the propellant for a reaction engine, lower atomic mass is better because equipment is largely temperature limited, and lighter gas will get higher ...
16
votes
2answers
482 views

Can solid fuel leak?

Recently the ISRO GSLV launch was called off on account of a fuel leak. Other launches too have, on occasion, been called off for similar reasons. Fuel used to launch a craft to orbit may be solid, ...
12
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5answers
4k views

Can a rocket motor be shut off after ignition?

After ignition, if any problems occur such as fuel leakage, can a rocket motor can be shut off?
31
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3answers
12k views

Why are hydrogen-fluorine fuels not used for rockets more frequently?

Many rockets use hydrogen- and oxygen-based propellants as fuel. Why are hydrogen-fluorine fuels not used? It has a specific impulse of 390 seconds, higher than hydrogen-oxygen combustion (360 ...
12
votes
1answer
200 views

Are there any proposals to vacuum up gases in orbit for use as propellant?

Space stations like the ISS orbit at an elevation that puts them squarely in the Thermosphere, and while this has extremely rarefied gas (which is probably more accurately a plasma at many times), it ...
13
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1answer
1k views

Are MMH and UDMH interchangeable?

Can Monomethylhydrazine and Unsymmetrical dimethylhydrazine be used one in place of another for the class of the existing orbital maneuver engines (with reduced performance may be)? Such as Shuttle's ...
8
votes
2answers
395 views

Could waste methane be recycled as propellant on the ISS?

Under standard condition methane burns with oxygen in stoichiometric ratio of 1:2 to liberate 891 kJ/mol of energy. Why is the ISS not making use of the methane, which is expelled as waste instead? ...
14
votes
1answer
1k views

Changes made to ISRO GSLV-D5's CUS and FBTP since GSLV-D3's LH2/LOX CUS failure to sustain ignition?

The launch of the ISRO GSLV-D5 launching India's GSAT 14 advanced communications satellite (weighing 1,980 kg) is slated for 19th of August, 2013, flying in the GSLV Mk.2 configuration with an Indian-...
7
votes
2answers
714 views

Is it safe to use a coilgun or railgun as an engine inside the solar system?

Given a large iron body and a coilgun or railgun to impart thrust, You can turn an asteroid into a fuel tank (sort of). Sending large or small bits of iron at high speed towards someone is likely to ...
16
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3answers
2k views

In a cryogenic fuel rocket, at what pressure is the fuel injected into the engine?

The pressure in the Space Shuttle's main engines must be very high to get the vehicle off the ground (with the SRB assist, of course). With such high pressures inside the engine, how do you inject ...
10
votes
3answers
2k views

How much fuel would one need to launch a 1kg object from 100,000 feet?

Back in the old days of the cold war the US and Russia were trying to develop a Nuclear powered aircraft. Problems with radiation shielding and "safety" held them back. Let's say that they got this ...
16
votes
2answers
519 views

How does the launch risk posed by plutonium compare to the launch risk posed by propellants?

For outer solar system exploration, virtually the only feasible power subsystem are Radioisotope thermoelectric generators (RTGs). These include plutonium, which may carry considerable risks (see ...
13
votes
1answer
592 views

At what travel distances are ion engines faster and more efficient than conventional fuel engines?

According to Scientific American (February 2009), ion engines start off slow, but build up speed as they travel. At what travel distance would an ion engine (such as an ion thruster, a Hall thruster, ...
8
votes
3answers
512 views

What creative orbital maneuvers might I do to save fuel for a geosynchronous spacecraft?

I've heard that there might be some creative ways to get to Geosynchronous Orbit that could save a lot of fuel. How might I manage to make this happen?