How do Ha'taks move?

[K^2]

i always assumed that they used a form of magnetism as sublight propulsion i mean dont tauri ships still use combustable fuel?

Magnetism? Why? How?

And no. Other than boosters on 302s, no combustion rockets. But the sublights on larger ships do appear to be reaction drives of some sort. Ion drives, perhaps.

[Sealurk]

Magnetism? Why? How?

And no. Other than boosters on 302s, no combustion rockets. But the sublights on larger ships do appear to be reaction drives of some sort. Ion drives, perhaps.

I might be going off on a slight tangent here (and a near-terminal geek-out), but one of the things I never quite understood was why so many people think the Prometheus' and 304's main engines were ion drives, beyond the fact that "Ion Drive" is a cool-sounding phrase.

As I understand it, ion drives have feeble thrust, their main strength lying in excellent fuel efficiency compared to chemical rockets and the ability to build up substantial velocity over a long period of time. Even with a whopping great naquadah power source, powerful magnetic fields and inertial dampening, could Prommie's acceleration possibly be accomplished by that kind of engine - not to mention moving in atmosphere.

Okay, I'm taking this waaay too seriously, I know, and Stargate writers are not rocket scientists. But surely fusion drive is a more realistic explanation (plasma rocket at the very least) for Tau'ri sublight propulsion!

[knowles2]

304s uses a nuclear plasma engine, it was stated on one of the ship computer screens in one epidsode. They probably also uses a gravity drive for lift off an landings.

Promethious used chemical engine combine with a gravity drive.

301 uses a combination of jet engine, rocket engine an ramjet I believe. They later been equip with some sought anti gravity propulsion units as well as we have seen them hovering over atlantis.

The Gould gliders most likely glide on artificial gravity waves which it create it self. Ha'tak likely use the same technology. Al'kesh most likely uses the in universe version of a ion drive an probably anti gravity drive. Cargo ships are purely gravitational drive engine.

[Cmdr. Setsuna F. Seyei]

I think this is just one of the archaic theories and nothing more. But what else can be used to fantasize? It is better to use one of the archaic theories than the "pink elephant".

the idea is not archaic. See here: http://www.searleffect.com/free/overview.html

[Edi]

... But surely fusion drive is a more realistic explanation (plasma rocket at the very least) for Tau'ri sublight propulsion!

aha, and what does a fusion drive fundamentally differ from an advanced ion drive or plasma rocket? They are basically the same thing - spew out low mass with very high velocity (close to c) using an electromagnetic field... Ok, fusion drive... however you make it work, the same thing can be done with an advanced ion drive (plasma rocket) and that Naquadah generator...

Actually, when people say ion drive, I think they simply don't know that the real thing is a plasma rocket...

[Sealurk]

aha, and what does a fusion drive fundamentally differ from an advanced ion drive or plasma rocket? They are basically the same thing - spew out low mass with very high velocity (close to c) using an electromagnetic field... Ok, fusion drive... however you make it work, the same thing can be done with an advanced ion drive (plasma rocket) and that Naquadah generator...

Actually, when people say ion drive, I think they simply don't know that the real thing is a plasma rocket...

Fair point! Maybe it comes down to wanting to avoid using anything associated with the word 'Nuclear'. I remember a physicist telling me he couldn't get any sponsors interested in his design for a "nuclear fusion reactor" because 'nuclear' puts people off, and 'fusion' and 'reactor' don't help, but as soon as he referred to it simply as a "plasma electric generator", he had no end of interest!

[K^2]

As I understand it, ion drives have feeble thrust, their main strength lying in excellent fuel efficiency compared to chemical rockets and the ability to build up substantial velocity over a long period of time.

Modern ion drives, yes. But in principle, an Ion Drive can have substantial drive, and is the most energy efficient drive one can construct, with ability to trade between rate of propellant consumption and power consumption.

Besides, 304 is equipped with inertial dampeners, which in SG universe means that it needs relatively low thrust to accelerate.

Plasma rocket is exactly the same thing as Ion Drive.

The Gould gliders most likely glide on artificial gravity waves which it create it self.

No. That's like riding an electromagnetic wave you create yourself, and that's also known as a photon drive. Photon drive is terribly inefficient, and pure gravity drive would have exactly the same problem. It is a zero-rest-mass propulsion system, which can give you maximum thrust of W/c, where W is power consumption and c is the speed of light. That's an insane amount of power even considering gliders dampener.

Gliders are stated to have their inertial dampeners reduce their effective inertial mass to nearly zero. What they actually use for propulsion from there on is left unexplained.

[QuantumDragon]

I might be going off on a slight tangent here (and a near-terminal geek-out), but one of the things I never quite understood was why so many people think the Prometheus' and 304's main engines were ion drives, beyond the fact that "Ion Drive" is a cool-sounding phrase.

As I understand it, ion drives have feeble thrust, their main strength lying in excellent fuel efficiency compared to chemical rockets and the ability to build up substantial velocity over a long period of time. Even with a whopping great naquadah power source, powerful magnetic fields and inertial dampening, could Prommie's acceleration possibly be accomplished by that kind of engine - not to mention moving in atmosphere.

Okay, I'm taking this waaay too seriously, I know, and Stargate writers are not rocket scientists. But surely fusion drive is a more realistic explanation (plasma rocket at the very least) for Tau'ri sublight propulsion!

an ion drive doesn't have to have a low acceleration. as long as you have the fuel to dump in and the power to accelerate it you can acheive even more acceleration than a chemical engine. using magnetic fields the fuel can be accelerated to relativistic velocities. chemical thrust drops off as the forward acceleration of the craft excedes the expantion velocities of the fuel combustion. the reason that real MODERN ion drives are so weak is that we dont have the power capacity to use the stronger magnetic fields that would allow us to have greater fuen consumption and therefore more thrust

[K^2]

chemical thrust drops off as the forward acceleration of the craft excedes the expantion velocities of the fuel combustion.

No way in hell are you going to have high enough acceleration to even note this. Mass of the craft is much, much greater than the mass of the propellant in combustion chamber at any given time.

The main problem with chemical fuels is the inherently limited specific impulse. The specific impulse of an ion drive is only limited by power availability and relativistic limit. Specific impulse of any reaction drive cannot exceed c.

[Serenity000]

304s uses a nuclear plasma engine, it was stated on one of the ship computer screens in one epidsode. They probably also uses a gravity drive for lift off an landings.

Promethious used chemical engine combine with a gravity drive.

301 uses a combination of jet engine, rocket engine an ramjet I believe. They later been equip with some sought anti gravity propulsion units as well as we have seen them hovering over atlantis.

The Gould gliders most likely glide on artificial gravity waves which it create it self. Ha'tak likely use the same technology. Tel'tak most likely uses the in universe version of a ion drive an probably anti gravity drive. Cargo ships are purely gravitational drive engine.

cargo ships are tel'taks I think you mean Al'kesh has an ion drive.

[knowles2]

cargo ships are tel'taks I think you mean Al'kesh has an ion drive.

corrected.

[QuantumDragon]

No way in hell are you going to have high enough acceleration to even note this. Mass of the craft is much, much greater than the mass of the propellant in combustion chamber at any given time.

The main problem with chemical fuels is the inherently limited specific impulse. The specific impulse of an ion drive is only limited by power availability and relativistic limit. Specific impulse of any reaction drive cannot exceed c.

well we are talking about ground to orbit in 30 sec for prometheus so i'm kinda taking this arguement in that context

[K^2]

Ground to orbit in 30s is about 25g. That's just a few times more rapid than a modern orbit delivery vehicle. About the same as some ICBMs. No trouble at all for chemical rocket to keep up with.

[QuantumDragon]

ok fine, you got me there.

on the other hand chemical propultion is inefficient as most of the energy of the fuel is spent in a manner other than generating thrust whereas an electromagnetis propultion system can generate the same thrust with no energy being wasted as light or heat.

[Mister Oragahn]

Ground to orbit in 30s is about 25g. That's just a few times more rapid than a modern orbit delivery vehicle. About the same as some ICBMs. No trouble at all for chemical rocket to keep up with.

I'd say more like 888.889 m/s², or 90.7 g, and that's not counting fighting against gravity. Since at 400 km, the local g' would be of 8.69 m/s², let's pull an average between g and g' and make that 9.245 m/s².Then, times 30, or 28.3 g.

The total is 119 g.

I picked 400 km cause that's the highest orbit for the ISS, and that station is certainly not going to suffer from the same atmospheric drag as the Prometheus would.

Would the ship's mass be 500,000 metric tons, with such an acceleration its engines would have to be capable of generating at the very least a power of 3.4 e14 W (like 5 to 6 Hiroshima nukes per second), and that's while ignoring thrust, fuel efficiency concerns and conservation of momentum.

I suspect therefore that the ship cheat that with anti-gravity tech, and therefore it means that a ship's acceleration in space is not so stellar.