28
votes
Would launching a shuttle from a 45 degree angle be the most fuel efficient for a rail gun?
Two issues:
Any orbit achieved will (discounting perturbations) pass through the point at which it was last altered by some external force. In the case of your rail gun, if it's on the ground, any ...
- 17.3k
18
votes
Would launching a shuttle from a 45 degree angle be the most fuel efficient for a rail gun?
To keep the acceleration manageable, you need a very long rail gun: say 8000 m/s of speed needed, 40 m/s2 acceleration (4G), that's 8000/40= 200 seconds of 'flight' on the rail. That's 800 km. That's ...
- 128k
10
votes
Would launching a shuttle from a 45 degree angle be the most fuel efficient for a rail gun?
45 degrees is probably not ideal.
...but it depends on your shuttle design.
To get to orbit, you need to go fast, not high. It's hard to go fast at low altitudes though, because there is a lot of ...
- 1,009
10
votes
Accepted
Orbital Railgun for launching deep space probes
Concepts for mass-drivers or railguns situated on the moon exist.
What you're asking about is a mass driver space station in low earth orbit that a payload or ship launched from earth can dock with, ...
- 6,458
10
votes
Orbital Railgun for launching deep space probes
Let's look at some numbers. For the sake of argument let's target a delta-V from the railgun of 4 km/s enough to get to low lunar orbit or Mars transfer orbit.
If the railgun is 1km long, that would ...
- 19.6k
7
votes
Would launching a shuttle from a 45 degree angle be the most fuel efficient for a rail gun?
Ignoring the atmosphere, let's say you're launching from the moon, the best angle to launch at would be 0 degrees.
This way you can accelerate to orbital speed at sea-level plus however much you need ...
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5
votes
Is railgun propulsion being researched?
I suspect that if you have the electric power available to fire macroscopic projectiles from a railgun, you're better off accelerating Xenon gas with it. Current ion thrusters yield exhaust velocities ...
- 169k
5
votes
Accepted
Is railgun propulsion being researched?
Yes, Made on Space is researching a similar idea. Plan to Turn Asteroids Into Spaceships
the propulsion system might be some sort of catapult that launches boulders or other material off the ...
- 1,392
4
votes
Ideal shape for a long, skinny reaction mass for LEO to cis-lunar and beyond? (a "space rail gun")
I've answered some aspects of this, but considering a 1km railgun in my answer to the "parent" question. A much longer railgun doesn't make a lot of difference to the calculations there, except for ...
- 19.6k
3
votes
Orbital Railgun for launching deep space probes
For the purpose of orbiting other planets; this solution adds lots of complexity, without (almost) any benefit.
You still need propellant, both on the craft and the railgun
The probe still need a ...
- 12.6k
3
votes
Accepted
Electromagnetic accelerator in space
According to Newton, for every action there is an equal and opposite reaction. As the magnets were applied to the craft, it would apply as much force on the accelerator. The accelerator would have to ...
- 376
3
votes
Accepted
Can I push the atmosphere out of the way?
Some starting numbers here would be that the leading hypersonic projectile will be scooping up a cylinder of atmosphere equal to the frontal area and it's traveled path. The first approximation of the ...
- 22.4k
3
votes
Ideal shape for a long, skinny reaction mass for LEO to cis-lunar and beyond? (a "space rail gun")
Having asked and thought about a similar question, I think the answer is simple. Don't build accelerators for humans. Build them for cargo.
The total mass of cargo that a human needs to be ...
- 355
2
votes
What limits are put on mission profiles by maximum tolerated G-force?
The Moon escape velocity is 2380 m/s.
For a constant acceleration, the needed distance and time are:
...
- 49k
2
votes
Accepted
Can ISS trash be used as reaction mass for orbital maintenance
Guns would not be practical--you get more boost by simply bringing up rocket fuel than with gun propellant throwing trash.
However, this does not preclude a mass driver approach. Break the trash into ...
- 11.5k
2
votes
Can ISS trash be used as reaction mass for orbital maintenance
Yeeeeees, it can.
For some very horrid variants of the word "can", which includes things like "Can students make a good bonfire? Yes they can, if you stack them high enough before ...
2
votes
Is railgun propulsion being researched?
From a science fiction perspective, there is a book Heart of the Comet by Gregory Benford and David Brin about an attempt to corral Halleys comet into Earth orbit. At apogee, they use mass-slingers, ...
- 79.6k
2
votes
Is it possible to launch picosatellite into orbit from railgun on high-altitude plane?
Another problem that would rear it's ugly head if you were to try this: Wake turbulence.
Your satellite will be leaving the barrel at a stupendous velocity. It's going to slam into the atmosphere ...
- 11.5k
2
votes
Is it possible to launch picosatellite into orbit from railgun on high-altitude plane?
Is it possible? Yes, but not with current technology (sorry not sorry for that pun). Right now railguns can't shoot projectiles fast enough to launch picosats from altitude. At least that's what my ...
- 167
2
votes
Accepted
would launching from a vacuum tunnel in a mountain from a 45 degree angle be the best way to launch a space shuttle
Yes, No, Maybe.
First, you have to define what is the "best way"
Considering the technology for such a railgun is science fiction it's impossible to answer you without detailed parameters.
Firsts ...
- 12.6k
1
vote
Would launching a shuttle from a 45 degree angle be the most fuel efficient for a rail gun?
As many before me have commented, there is a trade-off between gaining altitude (for purposes of reducing drag and raising the highest possible perigee) and gaining horizontal speed (reducing ...
1
vote
Would launching a shuttle from a 45 degree angle be the most fuel efficient for a rail gun?
As others have mentioned, orbits pass through the last point where a force acted upon the body, so a 45 degree angle shot will (attempt) to pass back through the ground at the point of launch at the ...
- 294
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