Staged TL8/9 spacefighters

raniE · 10-27-2008, 04:26 PM

So I bought GURPS Spaceships recently (Friday) and looking at it got me fired up to make a setting somewhat similar to new Battlestar Galactica, that is carrier ships carrying space fighters, and to do it with fairly hard science at either TL9 or possibly TL8. I've also decided that the spacefighters will use either either the chemical or HEDM rocket type from Spaceships. The problem is of course that neither gives much in the way of delta-V. So, my question to people with more experience with the spaceship combat system is this: Is the delta-V available by making the fighters two-staged worth the cost (in the TL9 version the booster costs almost as much as the actual ship, and is not usually reusable)?

vicky_molokh · 10-27-2008, 04:35 PM

AFAIK fighters are almost never worth the cost.

raniE · 10-27-2008, 04:45 PM

Quote:

Originally Posted by Molokh

AFAIK fighters are almost never worth the cost.

No, but they're cool.

The question of whether the cost of the extra delta-V is worth it can be generalized to other types of combat spacecraft using chemical or HEDM engines too of course (the delta-V amounts in the TL9 case would be 8.4 mps without staging and 15.4 mps with an extra stage).

SuedodeuS · 10-27-2008, 04:54 PM

Fighters are cool, but they aren't that viable in a low TL hard science setting. You might want to take a look at some of the superscience options to see if any of those give you a good delta-v and acceleration combination. I think a lot of them explain why they are superscience, so you can decide if it's too much of a stretch for your setting. Provided your current choices give you a good enough delta-v for combat but not for distance travel, you might want to consider using one of the low acceleration drives in addition to the high performance one(s). So, you could use an ion engine or something for travel, then switch over to the HEDM when you need to fight.

raniE · 10-27-2008, 05:00 PM

Quote:

Originally Posted by SuedodeuS

Fighters are cool, but they aren't that viable in a low TL hard science setting. You might want to take a look at some of the superscience options to see if any of those give you a good delta-v and acceleration combination. I think a lot of them explain why they are superscience, so you can decide if it's too much of a stretch for your setting. Provided your current choices give you a good enough delta-v for combat but not for distance travel, you might want to consider using one of the low acceleration drives in addition to the high performance one(s). So, you could use an ion engine or something for travel, then switch over to the HEDM when you need to fight.

Well, the idea would be for the carrier ship to have an engine with low acceleration and high delta-V, while the fighters have high acceleration and low delta-V engines.

vicky_molokh · 10-27-2008, 05:01 PM

Quote:

Originally Posted by raniE

No, but they're cool.

The question of whether the cost of the extra delta-V is worth it can be generalized to other types of combat spacecraft using chemical or HEDM engines too of course (the delta-V amounts in the TL9 case would be 8.4 mps without staging and 15.4 mps with an extra stage).

If it's a question of coolness, I'll probably keep my comments to myself, as I can only leave remarks regarding why fighters are done wrong, and not about how various numbers interact in specific ways.

Ulzgoroth · 10-27-2008, 05:05 PM

I'd actually contest that at that TL, nothing but fighters is going to be worth the cost. Especially if TL8/9 means pre-laser.

Chemical rocket engines are tricky, though. How far do you want your fighters to be able to fly? Because 24 hour canned life support doesn't actually let you get terribly far on modest delta-V budgets if you want to make a return trip.

For instance, 10 mps will about get you to extreme range and back. An entire stage worth of HEDM fuel is good for 10.4 mps

New Galactica is not within spitting distance of TL9 hard science. Fair warning. The capital ship is way too tough, and most of the ranges are easily a thousand times too short.

(Ok, the nuke aside, a minor eek goes out to people who built a warship that's apparently around SM+17)

raniE · 10-27-2008, 05:18 PM

Quote:

Originally Posted by Ulzgoroth

I'd actually contest that at that TL, nothing but fighters is going to be worth the cost. Especially if TL8/9 means pre-laser.

Chemical rocket engines are tricky, though. How far do you want your fighters to be able to fly? Because 24 hour canned life support doesn't actually let you get terribly far on modest delta-V budgets if you want to make a return trip.

For instance, 10 mps will about get you to extreme range and back. An entire stage worth of HEDM fuel is good for 10.4 mps

New Galactica is not within spitting distance of TL9 hard science. Fair warning. The capital ship is way too tough, and most of the ranges are easily a thousand times too short.

Oh sure, I know that the BSG is not exactly hard science, it's just sort of an inspiration. As for how far the ships are supposed to fly, it's not really how far, but how long they will be able to keep up maneuvering. Dodging bullets and missiles while trying to get in a position to destroy the enemy requires an almost constant expenditure of delta-V, even if you're operating in a relatively small area. So the question is, is 7-8 extra mps of delta-V going to be useful in combat, significantly extending the time a fighter can keep fighting before having to return to refuel?

The entire stage would be 7 mps delta-V by the way (2 engines for 4G thrust capacity and 2 armor systems leaves 10 systems for fuel tanks), somewhat more for the actual ship as opposed to the possible booster stage (got some room left over for fuel in the front section too). Also, no laser weapons will be available.

Ulzgoroth · 10-27-2008, 05:31 PM

7-8mps is quite a lot of combat time if used cautiously. You can maintain minimum tactical thrust for at least 40 minutes on that, which is probably longer than any battle would last. The problem is that unless the battle occurs right on top of the carrier (in which case, bye-bye carrier, really) you need to be able to get to the fight as well.

If you want to, you could go through it all much faster (especially with dual engines), but such high-thrust maneuvers don't actually net you any particular advantage in combat. Once you're burning enough fuel to be allowed a dodge and a maneuver, the rest is kind of pointless. Jockeying for position doesn't really happen when you're blotting your enemies out of space at 30,000 miles.

David Johnston2 · 10-27-2008, 05:34 PM

Quote:

Originally Posted by Ulzgoroth

7-8mps is quite a lot of combat time if used cautiously. You can maintain minimum tactical thrust for at least 40 minutes on that, which is probably longer than any battle would last. The problem is that unless the battle occurs right on top of the carrier (in which case, bye-bye carrier, really) you need to be able to get to the fight as well.

Isn't that what the carrier's catapult is for?

10-27-2008, 04:26 PM	#1
raniE Join Date: Jun 2007	Staged TL8/9 spacefighters So I bought GURPS Spaceships recently (Friday) and looking at it got me fired up to make a setting somewhat similar to new Battlestar Galactica, that is carrier ships carrying space fighters, and to do it with fairly hard science at either TL9 or possibly TL8. I've also decided that the spacefighters will use either either the chemical or HEDM rocket type from Spaceships. The problem is of course that neither gives much in the way of delta-V. So, my question to people with more experience with the spaceship combat system is this: Is the delta-V available by making the fighters two-staged worth the cost (in the TL9 version the booster costs almost as much as the actual ship, and is not usually reusable)?

10-27-2008, 04:35 PM	#2
vicky_molokh GURPS FAQ Keeper Join Date: Mar 2006 Location: Kyïv, Ukraine	Re: Staged TL8/9 spacefighters AFAIK fighters are almost never worth the cost. __________________ Vicky 'Molokh', GURPS FAQ and uFAQ Keeper

10-27-2008, 04:54 PM	#4
SuedodeuS Join Date: Sep 2008	Re: Staged TL8/9 spacefighters Fighters are cool, but they aren't that viable in a low TL hard science setting. You might want to take a look at some of the superscience options to see if any of those give you a good delta-v and acceleration combination. I think a lot of them explain why they are superscience, so you can decide if it's too much of a stretch for your setting. Provided your current choices give you a good enough delta-v for combat but not for distance travel, you might want to consider using one of the low acceleration drives in addition to the high performance one(s). So, you could use an ion engine or something for travel, then switch over to the HEDM when you need to fight. __________________ Quos deus vult perdere, prius dementat. Latin: Those whom a god wishes to destroy, he first drives mad.

10-27-2008, 05:05 PM	#7
Ulzgoroth Join Date: Jul 2008	Re: Staged TL8/9 spacefighters I'd actually contest that at that TL, nothing but fighters is going to be worth the cost. Especially if TL8/9 means pre-laser. Chemical rocket engines are tricky, though. How far do you want your fighters to be able to fly? Because 24 hour canned life support doesn't actually let you get terribly far on modest delta-V budgets if you want to make a return trip. For instance, 10 mps will about get you to extreme range and back. An entire stage worth of HEDM fuel is good for 10.4 mps New Galactica is not within spitting distance of TL9 hard science. Fair warning. The capital ship is way too tough, and most of the ranges are easily a thousand times too short. (Ok, the nuke aside, a minor eek goes out to people who built a warship that's apparently around SM+17) Last edited by Ulzgoroth; 10-27-2008 at 05:19 PM.

10-27-2008, 05:31 PM	#9
Ulzgoroth Join Date: Jul 2008	Re: Staged TL8/9 spacefighters 7-8mps is quite a lot of combat time if used cautiously. You can maintain minimum tactical thrust for at least 40 minutes on that, which is probably longer than any battle would last. The problem is that unless the battle occurs right on top of the carrier (in which case, bye-bye carrier, really) you need to be able to get to the fight as well. If you want to, you could go through it all much faster (especially with dual engines), but such high-thrust maneuvers don't actually net you any particular advantage in combat. Once you're burning enough fuel to be allowed a dodge and a maneuver, the rest is kind of pointless. Jockeying for position doesn't really happen when you're blotting your enemies out of space at 30,000 miles.