[Spaceships] Actually GMing a world with Pseudovelocity drives?

[vicky_molokh]

Greetings, all!

I'm curious: how problematic is the actual implementation of a setting where all space drives (or at least all Inertialess drives) are Pseudovelocity drives. Specific things that I suspect would warrant special consideration:

• missiles;
• shells from 'normal' guns;
• bombs;
• AKVs;
• the whole issue of breaking/deceleration and Reversals (or whatever it is called, from SS4);
• takeoff and reentry.

Anybody has good knowledge of these issues and their interaction with PV drives?

Thanks in advance!

[David Johnston2]

Well as soon a projectile left the pseudo-velocity sphere it would be moving at the ship's real speed plus it's acceleration. So I'd recommend not using guns and only using missiles with their own pseudo-v drives (meaning they'd do no momentum damage. You'd have to rely on the warhead).

[vicky_molokh]

Originally Posted by David Johnston2

Well as soon a projectile left the pseudo-velocity sphere it would be moving at the ship's real speed plus it's acceleration. So I'd recommend not using guns and only using missiles with their own pseudo-v drives (meaning they'd do no momentum damage. You'd have to rely on the warhead).

Well, just how much does it invalidate the use of shells and missiles?

[weby]

Originally Posted by Molokh

Greetings, all!

I'm curious: how problematic is the actual implementation of a setting where all space drives (or at least all Inertialess drives) are Pseudovelocity drives. Specific things that I suspect would warrant special consideration:[*]missiles;[*]shells from 'normal' guns;[*]bombs;[*]AKVs;[*]the whole issue of breaking/deceleration and Reversals (or whatever it is called, from SS4);[*]takeoff and reentry.[/list]
Anybody has good knowledge of these issues and their interaction with PV drives?

Thanks in advance!

Basically any attack form that uses kinetic energy is useless unless it can gain that kinetic energy somehow.

Thus if the pseudovelocity drive is capable of lifting a ship to orbit, that ship could then drop a bomb and let the gravity do the stuff.

This and other acceleration issues are a good reason to not allow pseudovelocity drives to work in strong gravity wells.

If the pseudovelocity drive was usable in lifting the ship up from a gravity well, the ship could just repeat: "raise, turn off pseudovelocity, dive to gain energy" until it has way too much potential energy thus loosing one of the main reasons in having psedovelocity drives. (no C-fractional strikes of starships on planets)

Originally Posted by Molokh

Well, just how much does it invalidate the use of shells and missiles?

In most likely scenarios the kinetic energy of a projectile is thus neglible, whereas in "more realistic" games kinetic energy is a true killer.

As said a missile with a Pseudo velocity drive is still fully usable if it can carry a warhead capable of damaging ships.

Ofcourse if the pseudovelocy drives have low acceleration then a short range kinetic missile using a non pseudovelocity drive would still work.

In general a raw pseudovelocity drive is most gameable if it is deep space use only or alternatively you say "normal physics does not work wih pseudovelocity drives" and wave away the problems.

[David Johnston2]

Originally Posted by Molokh

Well, just how much does it invalidate the use of shells and missiles?

"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.

[Ulzgoroth]

Or you could change your pseudovelocity. Make it 'sticky'. Objects moving with pseudovelocity retain pseudo-inertia even if they have no active pseudovelocity drive. Optionally, it could bleed off slowly enough not to pose a problem for your projectile weapons.

This is not going to negate the fact that pseudovelocity collisions are deeply weird. Two objects can slam into each other with a near-c closing pseudovelocity while their 'real' velocities are pointing away from each other...what happens?

This could be negated if you make the pseudovelocity system kill normal momentum relative to a locally privileged reference frame. Yes, physics is suddenly very upset with you, but at least you no longer have to know your target's native velocity before you can shoot them...

[thalassogen]

We are using (some kind of) pseudo-velocity drives in our GURPS Firefly game. The grav drive unit "just reduces the inertia of the ship" (as Serenity RPG states) by 99% for "forward motion" only. The real propulsion systems are fusion rockets/torches. While the grav drive is activated the rockets are 100 times as efficient (sAcc * 100, mps * 100). This affects only speed and travel time (as long as the drive is active), not kinetic/collision damage (that is just the 1% of real mps expended). Shutting down the drive immediately drops speed back to the real 1%.

Hope that helps.

EDIT: during fights grav drives are normally switched off, but switching them on is commonly used to escape; in general we try to avoid fights as they are too expensive

[Kax]

Originally Posted by David Johnston2

"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.

[Johnny1A.2]

Originally Posted by Kax

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...

[Anaraxes]

Originally Posted by Kax

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?