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Old 03-06-2011, 05:57 PM   #31
Fred Brackin
 
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Default Re: [Spaceships] Actually GMing a world with Pseudovelocity drives?

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Originally Posted by vicky_molokh View Post
An idea for another solution to the question of kinetic/potential energy and similar stuff - how about a PV drive:
  • Has a an effect that makes this pseudo-velocity semi-persistent - it 'bleeds off' gradually if the drive is turned off (or if it exceeds the drive/ship's max PV), and it is reduced or redirected significantly on a collision (e.g. PV loss/deflection is 50× the value of normal velocity's loss/deflection).
  • Has an effect that neutralizes 'real' velocity opposing its movement direction first, and only then starts giving PV. So if objects moves downward at 10 m/s, the PV drive of 1m/s² will spend the first 10 seconds neutralizing real speed, and spend the next 10 seconds giving PV upwards.
  • (Optional) A PV drive grants a speed that is pseudo in a large fraction, but not completely. E.g. a drive/ship combo rated for 50mps of PV actually attains a speed of 5 'real' mps and 45 pseudo-mps.
Well if love un-needed complexity.

When you turn on a PV drive you are violating the laws of physics as we understand them. You're doing it pretty severely too. You are effectively de-coupling the ship from interacting with all massive particles. It's halfway to hyperspace. It does protect you from cosmic rays as a handy side effect.

Retaining a "real" velocity comes quite close to declaring the frame of reference where you turned on the drive to be "preferred". At least I'm not sure how you calculate a "real velocity" on a universal basis without a preferred frame of reference.

Really, you broke the rules when you turned on the drive. The easiest thing to do is avoid trying to "repair" the rules when the drive shuts down. Just declare that the ship gained a "normal" velocity compared to the nearest significant object in adjacent space.

You probably do need some technobabble explaining this but something about "interactions with higher dimensions" ought to cover it.

Do as you please but but adding quasi-arbitrary complications doesn't make PV drives any harder physics.
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Old 04-25-2012, 10:05 AM   #32
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Default Re: [Spaceships] Actually GMing a world with Pseudovelocity drives?

Quote:
Originally Posted by vicky_molokh View Post
An idea for another solution to the question of kinetic/potential energy and similar stuff - how about a PV drive:
  • Has a an effect that makes this pseudo-velocity semi-persistent - it 'bleeds off' gradually if the drive is turned off (or if it exceeds the drive/ship's max PV), and it is reduced or redirected significantly on a collision (e.g. PV loss/deflection is 50× the value of normal velocity's loss/deflection).
  • Has an effect that neutralizes 'real' velocity opposing its movement direction first, and only then starts giving PV. So if objects moves downward at 10 m/s, the PV drive of 1m/s² will spend the first 10 seconds neutralizing real speed, and spend the next 10 seconds giving PV upwards.
  • (Optional) A PV drive grants a speed that is pseudo in a large fraction, but not completely. E.g. a drive/ship combo rated for 50mps of PV actually attains a speed of 5 'real' mps and 45 pseudo-mps.
After being forgotten for a long time, it seems that indeed I'll have to use an arrangement similar to the one above in my Æthereal Sun campaign. Here's how and why:

Mono-Polarised Displacers are the setting's semi-reactionless drives. The setting is sketchy on whether Einstein or Newton got the universe right. Basically, I'm intending to say that there is a semi-preferred frame against which the drive pushes, and this frame gradually matches that of the most gravitationally influential nearby objects (i.e. planet in its orbit, moon when really close to it, but sun when in the general vicinity of the star system).

Since MPDs produce ½-1G of thrust per system and consume one Power Point, that gives us roughly 1MW/10kN, or a speed limit of 100m/s for 'real' velocity (otherwise we get perpetual motion engines). So everything above 100m/s* has to be Pseudovelocity. Nicely, this solves the issue of collisions with planets by limiting collision energy to that of 100m/s-speed collision.

Sure, some collision courses can be set up in such a way that the 'natural' speed will still cause an impact, but it's not that trivial any more. I think.

Basically, PV doesn't go away on simple drive shutdown immediately, but is 'bled off' both by entering a different dominant gravity frame and by interacting with the world in other ways.

So . . . surely there are more unforeseen troubles. Anyone who can already see them?

* == Alternatively, MPDs can have 'shifting gears' which reduce thrust but increase the real-speed limit.
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Old 04-26-2012, 07:02 PM   #33
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Default Re: [Spaceships] Actually GMing a world with Pseudovelocity drives?

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Originally Posted by David Johnston2 View Post
"Our weapons fire at the speed of light and our engines move us at faster than the speed of light."

"So?"

"We just shot our own ship down."

Unless the projectiles have their own pseudovelocity propulsion, the ship will collide with them if it is firing forward at any speed worth mentioning. It could I suppose launch them rearward or to the sides.

This came up in an E. E. Doc Smith novel about why missiles were the only weapons used in FTL space battles--beams won't get to the target, and projectiles are right out.
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Old 04-26-2012, 08:28 PM   #34
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Default Re: [Spaceships] Actually GMing a world with Pseudovelocity drives?

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This came up in an E. E. Doc Smith novel about why missiles were the only weapons used in FTL space battles--beams won't get to the target, and projectiles are right out.
Then they worked out a clever way to make a projectile work...
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Old 04-26-2012, 10:08 PM   #35
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Default Re: [Spaceships] Actually GMing a world with Pseudovelocity drives?

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This came up in an E. E. Doc Smith novel about why missiles were the only weapons used in FTL space battles--beams won't get to the target, and projectiles are right out.
Whatever happened to all those ravening beams, rods, cones, stilettos, icepicks, corkscrews, knives, forks, and spoons of collimated energy I seem to remember from the Lensman books?

Last edited by Anaraxes; 04-26-2012 at 10:34 PM.
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Old 04-26-2012, 10:25 PM   #36
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Default Re: [Spaceships] Actually GMing a world with Pseudovelocity drives?

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Originally Posted by Anaraxes View Post
Whatever happened to all those ravening beams, rods, cones, stilettos, icepicks, corkscrews, knives, forks, and spoons of energy of collimated energy I seem to remember from the Lensman books?
The novel was said to be "an E. E. Doc Smith novel" not a Lensman novel. The Bergenholm means that any attack even lasers will just push the enemy away. They use tractor beams to keep it in place to blast it with starkly astounding ravening beams. Well after shooting it and throwing explosives at it in stubborn refusal to face the fact that aside from negamatter, free planets, and free N-Space planets kinetic weaponry and explosives have been obsolete for most of the books.

Last edited by Sindri; 04-26-2012 at 10:29 PM.
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Old 04-28-2012, 12:39 AM   #37
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Default Re: [Spaceships] Actually GMing a world with Pseudovelocity drives?

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Originally Posted by Anaraxes View Post
Whatever happened to all those ravening beams, rods, cones, stilettos, icepicks, corkscrews, knives, forks, and spoons of collimated energy I seem to remember from the Lensman books?

Those were used for non-FTL battles. Also, it was early on and they hadn't got to sophisticated stuff with force beams yet. :)
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Old 04-28-2012, 12:45 AM   #38
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Default Re: [Spaceships] Actually GMing a world with Pseudovelocity drives?

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For one thing - pseudovelocity is the best explanation I've heard for Star Wars and its imitators type spacecraft behaviour. Far better and more consistent with what we see on screen than the argument that these ships must be capable of thousands of g of acceleration... and yet for some reason all choose to spend most of their time doing nothing of the sort. If Luke was feeling pressured by Darth Vader as they roared down that trench - why didn't he just execute a few thousand g turns, lose the bad guys, and get back to shooting that exhaust port? Hmmm?

The actual explanation is that the fighter battles in the first three movies used footage from the Battle Of Britain for the movements, which is why X-wings move like they have rudders. :) The novels solidified this by referring to Ether Rudders for cornering and manoeuvring purposes.

larger ships used water ship combat, then specified that they were not properly in orbit just at an altitude, which is why badly damaged ships go nose down and start to leave the fight.

With ether manoeuvring controls and orbit held by gravity plates, SW space battles are valid. ;)
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Old 04-28-2012, 07:55 AM   #39
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Default Re: [Spaceships] Actually GMing a world with Pseudovelocity drives?

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This came up in an E. E. Doc Smith novel about why missiles were the only weapons used in FTL space battles--beams won't get to the target, and projectiles are right out.
I do not believe this to be accurate.

Doc's Bibliography is at the bottom of this.....

http://en.wikipedia.org/wiki/E._E._Smith

......and I have read all of the fictional works in question. There was no situation such as you have mentioned in any of them that I can remember.

Specifically, In the Skylark and Lensmen novels FTL combat featured beams of energy that travelled at FTL speeds.

The two Subspace books used a subspace drive whether ships did not interact at FTL speeds. Same for Masters of Space.

In Galaxy Primes interstellar travel was by means of psionic teleportation and ship combat was by other psionic means.

There was little or nothing about FTL ships in the Family D'Alembert novella that Smith actually wrote and Lord Tedric was about Time Travel and medieval fantasy. Goldin and Eklunds continuations of these series are soemthing I can't comment on though I believe I read the Goldin works.
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Old 04-28-2012, 10:44 AM   #40
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Default Re: [Spaceships] Actually GMing a world with Pseudovelocity drives?

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I do not believe this to be accurate.


There was little or nothing about FTL ships in the Family D'Alembert novella that Smith actually wrote and Lord Tedric was about Time Travel and medieval fantasy. Goldin and Eklunds continuations of these series are soemthing I can't comment on though I believe I read the Goldin works.
Goldin's continuation just used a 'conventional' sfnal hyperdrive and called it subspace, it was just a part of the general background.

Smith himself considered the Skylark stories to be fantasy rather than SF because he simply ignored relativity entirely (matter in the Skylark world can travel as fast as it can be accelerated, there's no limit) and he also ignored the kinetic impactor issue (even without relativistic effects, any spacecraft moving at many times the speed of light is a WMD even under Newtonian physics, and Smith did know that).
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