The discussion centers on the effectiveness of nuclear propulsion, particularly nuclear thermal propulsion (NTP), and its potential applications in space travel. Participants explore theoretical aspects, comparisons with chemical propulsion, and the current state of technology.
Participants express varying levels of uncertainty regarding the effectiveness of nuclear thermal propulsion, with no consensus on its practical application or performance compared to existing systems.
The discussion highlights limitations in current knowledge, particularly the absence of in situ testing for nuclear thermal propulsion systems, which affects the ability to evaluate their effectiveness accurately.
The space shuttle does have rockets attached to it! It has three main engines (SSME). The large fuel tank contains the liquid oxygen and liquid hydrogen that is pumped through piping between the large tanks and Space Shuttle. The booster rockets (SRBs) provide the propulsion for the large tank. The SRBs then separate when the shuttle gets high enough to atmospheric drag reduces to the point that the tank can travel with the shuttle without being torn away.Josiah said:Hi I was wondering how fast a space shuttle could go, if it didn't have to first escape the earths gravity. As in if it had the rockets attached to it.
That would result in an exhaust velocity of a whopping 4,725,000 m/s (about 1.575% c, a specific impulse of 482,140 seconds). In a ship with a mass ratio of 10, it would have a delta V of 3.63% c. Now you're talkin...
No, I mean if it had the rockets still attached to it once it had left the earths atmosphere. And if they still had the full amount of fuel. How fast could it go?Astronuc said:The space shuttle does have rockets attached to it! It has three main engines (SSME). The large fuel tank contains the liquid oxygen and liquid hydrogen that is pumped through piping between the large tanks and Space Shuttle. The booster rockets (SRBs) provide the propulsion for the large tank. The SRBs then separate when the shuttle gets high enough to atmospheric drag reduces to the point that the tank can travel with the shuttle without being torn away.
Nuclear thermal propulsion alleviates the need for the chemical reaction between hydrogen and oxygen; the hydrogen is simply passed through the reactor core and thermal energy is conducted from the reactor fuel elements into the hydrogen. Even with only hydrogen, a Space Shuttle would still require a tank (vessel) to hold the hydrogen, whether external or internal.
The space shuttle is design to return to earth much like an aircraft, and thus serves in low earth orbit. For venturing further out from LEO, one would require a different configuration, much like Apollo system or the successor, Artemis.
https://www.nasa.gov/humans-in-space/artemis/
https://en.wikipedia.org/wiki/Artemis_program
So far, only ground tests of NTR systems have been tested (NERVA). There have been no in situ deployments of NTRs, so it is not clear how effective such a system would be. Theoretically, the specific impulse of a nuclear thermal system is about twice that of a hydrogen-oxygen chemical propulsion.
sbrothy said:In response to "That would result in an exhaust velocity of a whopping 4,725,000 m/s (about 1.575% c, a specific impulse of 482,140 seconds). In a ship with a mass ratio of 10, it would have a delta V of 3.63% c. Now you're talkin..."sbrothy said:My personal favorite:
https://projectrho.com/public_html/rocket/enginelist2.php#nswr
Although it might be pure scifi.
What does exhaust velocity mean? How does it translate to the speed of the rocket?
https://projectrho.com/public_html/rocket/enginelist2.php#nswr
Although it might be pure scifi.
sbrothy said:My personal favorite:
https://projectrho.com/public_html/rocket/enginelist2.php#nswr
Although it might be pure scifi.
For simplicity's sake, we will assume a shuttle in orbit with a fully fueled external tank. IOW, we won't factor in the Solid fuel boosters. The Shuttle itself has a mass of 75,000 kg. The external tank has a empty mass of 35,500 kg and holds 718,500 kg of fuel and oxidizer. This puts the fully fueled mass at 829,000 kg and the total "empty"mass at 110,500 for a mass ratio of ~7.5. The main engines of the shuttle have an exhaust velocity( Ve) of of ~4400 m/s. Delta v ( change in velocity_ can be found by Dv = Ve * ln(mass ratio) . So plugging the above numbers in, we get Dv = 4400 m/s *ln(7.5) = 8.87 km/sec. That's for a empty shuttle. If it had its full payload of 29,500 kg, this drops to 7.83 km/sec. ~3.2 km/sec of that will be used up just in achieving escape velocity from orbit. If we add in the solid boosters, this increases by about 4.7 km/secJosiah said:No, I mean if it had the rockets still attached to it once it had left the earths atmosphere. And if they still had the full amount of fuel. How fast could it go?
How many boosters would you need to go to the nearest star, in a human life time, or 100 years, again assuming there is no need to escape earths gravity.Janus said:For simplicity's sake, we will assume a shuttle in orbit with a fully fueled external tank. IOW, we won't factor in the Solid fuel boosters. The Shuttle itself has a mass of 75,000 kg. The external tank has a empty mass of 35,500 kg and holds 718,500 kg of fuel and oxidizer. This puts the fully fueled mass at 829,000 kg and the total "empty"mass at 110,500 for a mass ratio of ~7.5. The main engines of the shuttle have an exhaust velocity( Ve) of of ~4400 m/s. Delta v ( change in velocity_ can be found by Dv = Ve * ln(mass ratio) . So plugging the above numbers in, we get Dv = 4400 m/s *ln(7.5) = 8.87 km/sec. That's for a empty shuttle. If it had its full payload of 29,500 kg, this drops to 7.83 km/sec. ~3.2 km/sec of that will be used up just in achieving escape velocity from orbit. If we add in the solid boosters, this increases by about 4.7 km/sec