In space, big ships moves slower than small ships...@_@

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66 comments, last by Stangler 16 years, 1 month ago
If we are going by real life physics...should big space ships (battlecrusiers etc) move sluggish and slow compared to small fighters that are often portrayed as fast and maneuverable? Since space doesn't have friction and air resistance, won't the bigger engine on big ships compensate for its mass? But I guess for balance reasons we need to give big ships a weak point...
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inertia.
Quote:Original post by RDragon1
inertia.


The bigger engine should compensate for bigger inertia. (mass to propulsion ratio remains constant)
Keep in mind you'd have to scale the power of the engines up by the cube of the size differences. If your capital ship is a hundred times larger than a fighter, then it'd need engines a million times more powerful.

Forgot to add: I also don't know what sort of properties a futuristic spaceship would have, but most of the ones I've seen in sci-fi appear to have thrust properties proportional to their outtake, or the area of "glowy bits" at the back of the ship. If your engine thrust varies on output area but the thrust you need depends on volume, then you'd expect larger ships to be slower by a factor of their size: if you scale a ship up a hundred times, you'd expect it to be a hundred times slower.

[Edited by - Trapper Zoid on March 2, 2008 1:25:22 AM]
I suppose the argument would then be this:
why not outfit the smaller ship with the larger engines allowing it faster speeds in a zero friction environment? And are we assuming a zero directional vector during propulsion? Because if the ship happens to be part of a gravitational pull (nearby planets / stars / or an orbit of some sort) wouldn't it then require more energy to move said battlecruiser compared to the smaller fighters? But then we're moving from a friction argument to gravitational force argument. Still - it would have an effect on propulsion speeds vs mass.

- Xyphyx

(Just a thought - I'm no physicist)


-Nevermind - I like Trapper Zoids answer better...
The best justification I can think of is that a fighter craft that will be docked in a carrier when not in battle is light since it doesn't need to haul around supplies and crew accommodations and can have a engine thats lighter but less efficient since it can refuel after a mission.

so its logistical independence vs speed and maneuverability

It could also be possible that capital ships have more armor since their more valuable or to compensate for being a bigger target.
Quote:Original post by Trapper Zoid
Keep in mind you'd have to scale the power of the engines up by the cube of the size differences. If your capital ship is a hundred times larger than a fighter, then it'd need engines a million times more powerful.


Sorry, this isn't true. F=ma, so in order to accelerate a craft that is 100x larger you just need 100x the force. On top of that, you could probably make the larger engine more efficient because of the economy of scale.

If anything, Kaze's suggestion is the best. Large ships implies that the ship will tkae large trips that require increased fuel/supplies. In addition, they are larger targets and have to compensate with either stronger defense or offense, which invariably adds mass to the ship.
Turring Machines are better than C++ any day ^_~
Original post by intrest86
Quote:Original post by Trapper Zoid
Keep in mind you'd have to scale the power of the engines up by the cube of the size differences. If your capital ship is a hundred times larger than a fighter, then it'd need engines a million times more powerful.


Sorry, this isn't true. F=ma, so in order to accelerate a craft that is 100x larger you just need 100x the force. On top of that, you could probably make the larger engine more efficient because of the economy of scale.

No hes right, its just he's saying 100x as big is 100x times the size as in 100*longer. Then its volume would be 100^3. Volume grows cubically with length.
Original post by ibebrett
Quote:Original post by intrest86
Quote:Original post by Trapper Zoid
Keep in mind you'd have to scale the power of the engines up by the cube of the size differences. If your capital ship is a hundred times larger than a fighter, then it'd need engines a million times more powerful.


Sorry, this isn't true. F=ma, so in order to accelerate a craft that is 100x larger you just need 100x the force. On top of that, you could probably make the larger engine more efficient because of the economy of scale.

No hes right, its just he's saying 100x as big is 100x times the size as in 100*longer. Then its volume would be 100^3. Volume grows cubically with length.

Yes, that's what I meant. I should have written "longer" instead of "larger". Sorry about the confusion.

My point is that the engine power (probably*) grows proportional to the surface area of the ship, while the mass is proportional to the volume.

* This is sci-fi after all - who know how the engines work?
My new theory is that they are meant to fill different tactical roles. Large ships that have better offense and defense at the expense of speed for attacking at long range and holding lines as a semi mobile fortress and small fast ships that fight close up weaving through the enemy's lines make more sense than the other way around.

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