[Spaceships] Actually GMing a world with Pseudovelocity drives?

[Fred Brackin]

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.

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.

[Fred Brackin]

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?

I used a pseudovelocity drive in 2 campaigns and found it far, far simpler than normal accleration and deceleration in combat.

The rules were:

There is no energy transfer between colliding bodies while even one of the two has the PV drive is on.

If two PV bodies do collide they stop but regular kinetic weapons may fire without PV effects. A standard weapon was a PV missile with a SEFOP warhead.

I also invented a "sustainer coil" that was cheap enough to put into shells and kept the projectile in PV for approx. 1 second after firing. Effective pseudovelocity (and therefore range) was roughly 1000x normal atmospheric and guns were very common weapons. I imposed TS-like heat restrictions on beam weapons.

Maneuvering was just like in atmosphere and special vaccuum-only maneuvers were not allowed.

<shrug> It was easy and I have no intention of running space combat with "normal" drives in my own campaigns. KE weapons in those situations are a major PITA.

[capnq]

Not being familiar with the [Spaceships] series myself, could someone who is familiar with both comment on whether GURPS Lensman's Technology chapter would be a useful resource on this question? (Specifically, its treatment of inertialess drives.)

[Pomphis]

Depends. The Bergenholm makes the entire ship inertialess, with consequences for boarding actions: people inside the ship are inertialess too. Ships must usually be hold tractorbeams in combat to damage them, as most beams simply push them away. But Lensmen doesn´t care much about physics, so using it to design a campaign is much like using Tales of the Solar Patrol. Lensmen certainly is not bothered by relativity or stuff like that. Whether original momentum is retained is - IIRC - never discussed. And it is on a much larger scale: planetary bergenholms exist, and are countered by smashing the inertialess planet between two planets hitting it from opposite directions.

[Diomedes]

Originally Posted by Pomphis

Depends. The Bergenholm makes the entire ship inertialess, with consequences for boarding actions: people inside the ship are inertialess too. Ships must usually be hold tractorbeams in combat to damage them, as most beams simply push them away. But Lensmen doesn´t care much about physics, so using it to design a campaign is much like using Tales of the Solar Patrol. Lensmen certainly is not bothered by relativity or stuff like that. Whether original momentum is retained is - IIRC - never discussed. And it is on a much larger scale: planetary bergenholms exist, and are countered by smashing the inertialess planet between two planets hitting it from opposite directions.

Original momentum is indeed maintained; it comes back when the Bergenholm is switched off. In one book a rescue party had to match velocity in real space in order to retrieve the craft.

[Fred Brackin]

Originally Posted by Pomphis

Depends. The Bergenholm makes the entire ship inertialess, with consequences for boarding actions: people inside the ship are inertialess too.

The point about what is called "intrinsic velocity" made earlier is correct. It absolutely does "come back" when the Berg is switched off (even if this demands a preferred frame of reference).

Internal inertialessness is only the norm in early versions (specifically the Rodebush-Cleveland device rather than the Bergenholm itself). Artificial inertia is rapidly developed.

Patrolmen still train to deal with inertialess rnvironments in the era of Galactic Patrol and later books but it is seldom seen. SOP is to disable the Berg before you board.

[Anaraxes]

Hoverbombs would be the ultimate weapon

Spaceships doesn't go into a lot of detail, but I recall one sentence that says velocity acquired while under PV drive simply vanishes when you turn the PV off. So no hoverbombs with this definition of PV. Of course, this aggravates the matching course with Mars problem, as you can't gradually accumulate the proper vector while on your way. For interstellar travel it doesn't bear thinking about.

If you bounce radar off a ship under PV drive, what does the Doppler shift look like? I'd assume that you get Doppler readings for the true velocity. The radar equipment would have to determine your PV by taking the difference in position over different samples in time. The display probably returns both values as a matter of course.

Time dilation? It seems like half the point of PV would be to dodge such questions, so base it on true velocity. But Mach's Principle bugs me in that regard.

[vicky_molokh]

Originally Posted by Anaraxes

Spaceships doesn't go into a lot of detail, but I recall one sentence that says velocity acquired while under PV drive simply vanishes when you turn the PV off. So no hoverbombs with this definition of PV. Of course, this aggravates the matching course with Mars problem, as you can't gradually accumulate the proper vector while on your way. For interstellar travel it doesn't bear thinking about.

The velocity is matched with Mars upon turning of the drive in Mars' orbit automagically?

Originally Posted by Anaraxes

If you bounce radar off a ship under PV drive, what does the Doppler shift look like? I'd assume that you get Doppler readings for the true velocity. The radar equipment would have to determine your PV by taking the difference in position over different samples in time. The display probably returns both values as a matter of course.

As if the ship has a true velocity matched with the RADAR-using craft? ;)

[Ulzgoroth]

Originally Posted by Molokh

The velocity is matched with Mars upon turning of the drive in Mars' orbit automagically?

I'd be tempted to go one further and put you in a stable orbit around Mars when you shut off the pseudovelocity.

[Pomphis]

Originally Posted by Anaraxes

I recall one sentence that says velocity acquired while under PV drive simply vanishes when you turn the PV off. So no hoverbombs with this definition of PV.

The bombs do not acquire velocity while under PV. You use PV to go up to 1,000 miles. You switch off PV. You are accelerated downwards by gravity and gain real velocity. 900 miles down you switch PV on and go up to 1,000 miles again. Repeat.

Another option is to say that momentum is not maintained and that when PV is switched off the ship will be at rest relative to - for example - the mass having the greatest gravitional effect on this point of space.