Gravitic thrusters?

SharkHunter wrote: Would it be stealthy though? We're not told that the reaction thrusters are extremely visible because they're the tail of a chemical reaction, for example, but keep in mind that accelerating any quantity of any kind of molecule significantly is adding insane amounts of energy to them, that is, the molecules themselves aren't particle shielded and stealthed.

I think ANY form of particle thrust would end up having the "tail of a comet" type problem, and comets aren't even travelling at a super-significant fraction of C.

I do think that the pressed ejecta would light up brilliantly. If they're moving hundreds of thousands or millions of tons of shipping by inflicting an opposite force on a bit of gas, the bit of gas is going to undergo womdiginous acceleration.

The tractors should be very to entirely stealthy though: spider drives work by dragging themselves along by tractor to the alpha wall, so if tractors were bright and shiny, so would be the spider drive ships. That said, if tractors can be detected at all, that may be one of the better ways to try to detect a spider drive unit.

JeffEngel wrote:

SharkHunter wrote: Would it be stealthy though? We're not told that the reaction thrusters are extremely visible because they're the tail of a chemical reaction, for example, but keep in mind that accelerating any quantity of any kind of molecule significantly is adding insane amounts of energy to them, that is, the molecules themselves aren't particle shielded and stealthed.

I think ANY form of particle thrust would end up having the "tail of a comet" type problem, and comets aren't even travelling at a super-significant fraction of C.

I do think that the pressed ejecta would light up brilliantly. If they're moving hundreds of thousands or millions of tons of shipping by inflicting an opposite force on a bit of gas, the bit of gas is going to undergo womdiginous acceleration.

The tractors should be very to entirely stealthy though: spider drives work by dragging themselves along by tractor to the alpha wall, so if tractors were bright and shiny, so would be the spider drive ships. That said, if tractors can be detected at all, that may be one of the better ways to try to detect a spider drive unit.

Mostly the thrusters are used near ships to prevent deadly drive interactions. Possibly improved tractors could reduce the need for thruster. The rest makes sense, I don't see this as being stealthy unless there is absolute vacumn, ie nothing for the moving gas to interact with. I wonder if it could be used as a weapon, even a few ounces at near light speed would be very deadly; more momentum/energy than a laser/graser, although at the distances involved, it would be harder to make a hit with it.

DDHvi wrote:Mostly the thrusters are used near ships to prevent deadly drive interactions. Possibly improved tractors could reduce the need for thruster. The rest makes sense, I don't see this as being stealthy unless there is absolute vacumn, ie nothing for the moving gas to interact with. I wonder if it could be used as a weapon, even a few ounces at near light speed would be very deadly; more momentum/energy than a laser/graser, although at the distances involved, it would be harder to make a hit with it.

It can't get close to light-speed. I already pointed out the very short time that the material would be subject to acceleration before it moved out of range of the tractor beam.

The distance formula is d = (1/2) a t^2. The velocity formula is v = a t. So t = v / a. Replace t in the first formula: d = (1/2) a (v^2 / a^2), or d = (1/2) v^2 / a. Solve for a: a = (1/2) v^2 / d. This is of course the non-relativistic version, for simplicity.

So, if we wanted to reach the velocity of 50% light-speed (still non-relativistic), over the course of 100,000 km (the proposed range of this tractor beam), you would need an acceleration of 450,000,000 m/s^2, or about 46 million gees. And that's just to reach half of light-speed.

SWM wrote:

DDHvi wrote:Mostly the thrusters are used near ships to prevent deadly drive interactions. Possibly improved tractors could reduce the need for thruster. The rest makes sense, I don't see this as being stealthy unless there is absolute vacumn, ie nothing for the moving gas to interact with. I wonder if it could be used as a weapon, even a few ounces at near light speed would be very deadly; more momentum/energy than a laser/graser, although at the distances involved, it would be harder to make a hit with it.

It can't get close to light-speed. I already pointed out the very short time that the material would be subject to acceleration before it moved out of range of the tractor beam.

The distance formula is d = (1/2) a t^2. The velocity formula is v = a t. So t = v / a. Replace t in the first formula: d = (1/2) a (v^2 / a^2), or d = (1/2) v^2 / a. Solve for a: a = (1/2) v^2 / d. This is of course the non-relativistic version, for simplicity.

So, if we wanted to reach the velocity of 50% light-speed (still non-relativistic), over the course of 100,000 km (the proposed range of this tractor beam), you would need an acceleration of 450,000,000 m/s^2, or about 46 million gees. And that's just to reach half of light-speed.

And hopefully that little calculation will put a stake through the heart of this discussion (he says very hopefully)

SWM wrote:

DDHvi wrote:Mostly the thrusters are used near ships to prevent deadly drive interactions. Possibly improved tractors could reduce the need for thruster. The rest makes sense, I don't see this as being stealthy unless there is absolute vacumn, ie nothing for the moving gas to interact with. I wonder if it could be used as a weapon, even a few ounces at near light speed would be very deadly; more momentum/energy than a laser/graser, although at the distances involved, it would be harder to make a hit with it.

It can't get close to light-speed. I already pointed out the very short time that the material would be subject to acceleration before it moved out of range of the tractor beam.

The distance formula is d = (1/2) a t^2. The velocity formula is v = a t. So t = v / a. Replace t in the first formula: d = (1/2) a (v^2 / a^2), or d = (1/2) v^2 / a. Solve for a: a = (1/2) v^2 / d. This is of course the non-relativistic version, for simplicity.

So, if we wanted to reach the velocity of 50% light-speed (still non-relativistic), over the course of 100,000 km (the proposed range of this tractor beam), you would need an acceleration of 450,000,000 m/s^2, or about 46 million gees. And that's just to reach half of light-speed.

[edited]Sorry, slight miscalculation by a factor of 4. The correct value is 12 million gees.