[Spaceships] Missiles

[RyanW]

Originally Posted by Witchking

If it is the only choice, or if markedly superior, or if the other drive choices are dangerous in there own ways; then you might go for it. Otherwise a lot of naval designers might wish to avoid them...

Prior to TL9 there is simply no alternative to chemical rockets for achieving the 6G acceleration that seems standard for missiles, aside from external pulsed plasma which is impractical at any TL in something as small as a missile. At TL9+, HEDM offers significant improvements over chemical rockets at the expense of being more volatile. Nuclear thermal (at TL9+) and antimatter thermal (at TL10+) can both manage 6G, but only by taking every thrust boosting option and sacrificing so much fuel capacity that they have substantially less dV than more conventional rockets.

[Witchking]

Originally Posted by RyanW

Prior to TL9 <snip> substantially less dV than more conventional rockets.

Kewl...thats why I phrased my reply the way I did...my hands on GURPS SPACE experience is 3E or older...

So if the setting boxes one in like that as a naval designer I would be looking to "compensate" with appropriate Damage Control Systems...

Again much like the Americans at Midway who by chance (somewhat) were lucky enough to have their arm/rearm cycles running right so that ordinance was not scattered over the hangar deck. Also by design as they "invented" the idea of flooding the AV Gas transmission lines with CO2 prior to seeing action. These two steps taken together greatly lowered their combustibility and since "Fire Killls Ships!" kept them alive.

Both of those combined allowed US Carriers to take a greater pounding and stay afloat than their opponents.

Missles are worth having...but within the systems I would be looking to take steps to avoid the "Magazine Hit...no one had a chance to reach the lifepods" scenario.

my 2 creds

[Ulzgoroth]

Originally Posted by jacobmuller

Nice workups.
The payload space is the biggest puzzle for me.
With only 10% payload you can get TL7-8 5G, 5mps, TL9+ 10G 10mps*.
But SS3 has TL7-8 6G 6mps and TL9 5G 10mps. There's seems no way to get 6mps at TL7-8, unless I've got my numbers wrong (not a surprise) or the SS3 stats are wrong [errata?].

And then there's the probes - replace warhead with sensors, eg a 96cm drone has the same stats as an SM+5 vessel which puts the warhead weight at 5%...

*actually about 4.9 and 10.2 but they look nice GURPSed.

Unfortunately, the "Missiles are not built with spacecraft components" point means you can't draw interesting conclusions unless your Spaceship-missile can outperform the official missile.

Originally Posted by Witchking

Missles are worth having...but within the systems I would be looking to take steps to avoid the "Magazine Hit...no one had a chance to reach the lifepods" scenario.

my 2 creds

Missiles are must-have.

Officially (SS1:62) any section containing missiles is volatile and has a fairly significant chance to vaporize the ship if disabled or destroyed. Usually you'll have the duration of a space combat turn (however long that happens to be) to bail out.

[Fred Brackin]

Originally Posted by Witchking

Missles are worth having...but within the systems I would be looking to take steps to avoid the "Magazine Hit...no one had a chance to reach the lifepods" scenario.

Solid fuel rocket motors will burn of course but they won't explode if hit. HEDM would. HEDM goes "BOOM" if the tank fails in any way.

I actually never assumed anything but solid fuel for lower TL missiles. You still need something else for reaction control but solid fuel is safer than any other contemporary alternative for main propulsion (for missiles at least, that "no shut-off is a serious problem for other uses).

[Ulzgoroth]

Originally Posted by Fred Brackin

I actually never assumed anything but solid fuel for lower TL missiles. You still need something else for reaction control but solid fuel is safer than any other contemporary alternative for main propulsion (for missiles at least, that "no shut-off is a serious problem for other uses).

I'm pretty sure inability to shut off is unsuitable for RAW Spaceships missiles too. The SS3 mechanics allow them to start and stop thrusting at will.

[Fred Brackin]

Originally Posted by Ulzgoroth

I'm pretty sure inability to shut off is unsuitable for RAW Spaceships missiles too. The SS3 mechanics allow them to start and stop thrusting at will.

There's not a lot of good reason for them to do so. Change direction of thrust sure but you simply want as much velocity as possible on impact for KK missiles. Even for nukes you want as short a a closing time for defenses to work on the missile.

If the issue is coasting in the mid-phase of the transit time for very long range attacks you could make the missile two stage.

Anyway, don't overthink this. Spaceships isn't made for thsi sort of detail. The main book combat system doesn't even measure exact distances. Even the mapped system isn't very fine scale.

[Witchking]

Originally Posted by Fred Brackin

Anyway, don't overthink this. Spaceships isn't made for thsi sort of detail. The main book combat system doesn't even measure exact distances. Even the mapped system isn't very fine scale.

KK. I thought I might be dropping below the rules granularity.

The same impulse that made me buy a $40ish trade paperback on the US Airship program (I just cant help it...Zepplins with Trapeeze based Aircraft...pictures!!).

Good Luck Guys!!

[Wanderer]

Originally Posted by Ulzgoroth

Unfortunately, the "Missiles are not built with spacecraft components" point means you can't draw interesting conclusions unless your Spaceship-missile can outperform the official missile.

Actually space-to-space missiles are spacecrafts (as in reality and as per stated repeatedly in various GURPS books). Just as the same as the larger manned versions are.

Also i seriously doubt solid fuel rockets would be actually capable of '6G with 6 mps' performance. They are bound by the same laws of physics as other chemical rockets (liquid fuel). Since solid fuel things lack from the spaceships it 'needs' to be done in the hard way via Tsiolkovsky. With really optimistic assumptions and 5% payload i got 8.4 mps and with actual 30% payload (ie. the bomb) i get meager 3.4 mps. And that is with really optimistic values for both waste mass and for exhaust velocity, with more realistic ones i get 3.1 mps and 1.5 mps respectively.

[Fred Brackin]

Originally Posted by Wanderer

Actually space-to-space missiles are spacecrafts (as in reality and as per stated repeatedly in various GURPS books). Just as the same as the larger manned versions are.

Also i seriously doubt solid fuel rockets would be actually capable of '6G with 6 mps' performance. They are bound by the same laws of physics as other chemical rockets (liquid fuel). Since solid fuel things lack from the spaceships it 'needs' to be done in the hard way via Tsiolkovsky. With really optimistic assumptions and 5% payload i got 8.4 mps and with actual 30% payload (ie. the bomb) i get meager 3.4 mps. And that is with really optimistic values for both waste mass and for exhaust velocity, with more realistic ones i get 3.1 mps and 1.5 mps respectively.

Of course you do with 30% payload. A 6 mps chemical rocket needs needs the proportions of a Saturn 5.

Moral: You probably don't want to conduct Spaceships combat at TLs 7 and 8. A hard science TL9 is probably marginal. These are eras when dying in space is too easy without help.

[jacobmuller]

Originally Posted by Ulzgoroth

Unfortunately, the "Missiles are not built with spacecraft components" point means you can't draw interesting conclusions unless your Spaceship-missile can outperform the official missile.

Well, how about calling it an autonomous hunter killer kinetic kill small craft and designing it with SM+5 rules:)
The numbers I get from SM+5 stats using 5% control and 5% "cargo" are satisfying enough that I'll be happy with extrapolating to a TL10 limited superscience setting.

All I really needed to know was if I was doing the arithmetic correctly: at TL7-8 a vessel with 5% control, 5% cargo, 8.333'% drive and the rest fuel comes out as 5G and approx 5mps?

It's the thrust and delta-v bothers me - you can have 1 fuel tank and 6 drives and still get he smae delta-v, you just get there sooner - right?