Ion rocket engine powerfull enough for space flight?

[-Slacker-]

Take NIF or ITER and build either of them the size of a car?

 

[QuantumPion]

How are you going to get that much electricity onto a ship without using massive batteries, unwielding solar panels (which will never provide enough power at Earth distances from the sun), or fusion/fission power?

The problem of weight remains (except for fusion which doesn't work yet).

Again, there is no current better way to get into LEO without using chemical rockets. I am still waiting for that space elevator though.....

Actually we had working nuclear thermal rocket engines in the 60's capable or producing enough thrust for the Saturn V 2nd stage. With modern technology NTR's are well within the realm of feasibility for a Mars mission.

http://large.stanford.edu/courses/2011/ph241/hamerly1/

 

[SMOGZINN]

I see.

So, from what I gather, the thrust on an ion engine doesn't scale with the amount of electric power you feed it.

No, not at all.

What about using obscene amounts of electricity to heat up fuel inside a container to scorching temperatures and ejecting it at very high speeds, pretty much like a chemical rocket, but without the need to carry shitloads of fuel because the low amount of fuel this conceptual vehicle would carry would be offset by the much higher temperatures/pressures inside the ignition container, and thus the thrust could be equal or even greater than that of a chemical rocket? (The advantage would be that such a vehicle could take off like a plane because it can adjust it's trust, or even turn the engine off at the pilot's discretion)

If you had virtually unlimited amount of energy to work with you could just build something like a turbo-ramjet engine that would just get you going fast enough in atmosphere to slingshot you into near space, where you could switch over to Bussard ramjets to keep you going. Assuming you had the material science to build a flight structure strong enough to withstand the pressures needed to get to those speeds.

 

[greenhawk]

any news about them putting a spacecraft on a long magnetic rail that is positioned on the side of a mountain? using magnetic force, it would accelerate to astronomical speeds and simply sling the craft into space?

i think its possible, but they said the real challenge is to make a track long enough that there is enough time to accelerate slow enough that the g forces dont kill the passengers....

rusty with my physics but taking the escape velocity of earth at the surface being 11.2Km/s, a 1 G accelleration, from a standing start, you would need about 106 seconds of travel time, on about 600Km of track.

that is ignoreing air resistance, energy in turning "up" near the end and assuming no thrust from the object to assist launch.

aiming for the space station at about 400Km, having a small rocket engine and a higher acceleration of 2 G, will probably need a far shorter track. (something I might try to remember to have a crack at when I have the time and want to re-adjust the numbers).

Of course, being on Mt Everest as a exit point on the rail at about 8Km heigh (short of the peak), would only change the numbers a small bit given the radius of the earth is much larger at about 6,378 km (so effecting escape velocity). Ruff numbers with the formula for escape velocity puts 8Km high at 11.192Km/s vs 11.2Km/s at the surface. Against a mountin will only help with allowing a more gental ramp between horizontal and vertical.

 

[ArizonaSteve]

You're out by a factor of ten. Acceleration @ 1G (9.8 m/s2) would require around 1,150 seconds to reach 11.2 Km/s.

 

[PsiStar]

Ignoring air resistance is a biggy. That is, ignoring air friction ... the craft will burn up before it gets to the end of the ramp.

 

[DrPizza]

From the end of your ramp on, it will be slowing down due to air resistance. Once it's through the atmosphere, it has to reach the same speed that the space shuttle travels in space (and that's just for a low Earth orbit.) Think about that - on the way up, the Space Shuttle reaches that speed above most of the atmosphere. Then, when it comes back down, that's the maximum speed, and air resistance slows it down - a ton of energy is lost (and turned into heat. On the way up, you would have to greatly exceed that speed before air resistance slows it down to what was before, the max speed for the space shuttle.

So, no, you can't ignore air resistance.

 

[Howard]

http://books.google.ca/books?id=P8W...gG91fH3CQ&ved=0CE4Q6AEwAA#v=onepage&q&f=false

 

[Skabirian]

Hi my friends
this may be irrelevant to your topic so I'm sorry at first

I was planning to build a Ion thruster for my degree of Aerospace Engineering
so my Master told me go and search to find out how much it'll cost?
so if you know any references or other useful information on your own please contact me:
Skabirian@gmail.com
Thank you very much

 

[Lemon law]

Am I a nay sayer if I point out accelerating at 1G per second gets us no where. When the gravity of earh pulls us down at the same 1G per second.

 

[richaron]

Am I a nay sayer if I point out accelerating at 1G per second gets us no where. When the gravity of earh pulls us down at the same 1G per second.

9.8 metres per second per second per second just sounds confusing... But since youre talking about a rate of (rate of) change, I think it's safe to assume there is/has been movement.

 

[irishScott]

Am I a nay sayer if I point out accelerating at 1G per second gets us no where. When the gravity of earh pulls us down at the same 1G per second.

Depends on the direction. Accelerating 1G straight off the ground gets us nowhere, the acceleration vectors simply cancel out. Accelerating at 1G at an angle on the other hand...

 

[Abwx]

Sigh... space is depressing. We are so weak and limited.

What i was concluding as well...

Some dont realize that Wright was still beaten by birds , technicaly
speaking , but when i read about 10% light speed as being the same
step , i guess some dont realize this is numerous orders of magnitude higher..

 

[Abwx]

Depends on the direction. Accelerating 1G straight off the ground gets us nowhere, the acceleration vectors simply cancel out. Accelerating at 1G at an angle on the other hand...

Assuming you re in the air , temporarly suspended , if you accelerate
to the right at 1G you might go west at 9.8m/s2 but once the gravity
is working you ll fall at 9.8m/s2 you and your movement as a whole.....

 

[irishScott]

Assuming you re in the air , temporarly suspended , if you accelerate
to the right at 1G you might go west at 9.8m/s2 but once the gravity
is working you ll fall at 9.8m/s2 you and your movement as a whole.....

Oh... right. It's been a while since basic kinematics.

 

[Abwx]

Well , i was half right , surely , so you re still half right as well...

 

[GWestphal]

Either the world needs to become forward looking and intelligent about space exploration or we need a major discovery regarding harnessing gravity, electromagnetics, strong or weak forces differently than how we currently understand them. I wouldn't hold my breath on the former...