DrTemp

Re: Further thoughts about the UES Centauri and the AW space combat environment

The range of mark I lasers is 30' date='000 km [300" normal range mega-scaled to 1"=100 km']. That is a huge range scope of about 1/12 the distance between the earth and the moon. The range mod for that is about -14 but the size of the Xaeran Tro'Gah is -17 DCV so even at extreme range the Centauri is still +3 OCV to hit. The Xaeran is at -1 OCV to hit due to the Centauri's size.

I see. That allows for battles at much longer ranges than I anticipated, but I still believe that due to the limited delta-v available even with fusion rockets, the defender's usual tactics should be to wait in orbit and welcome the intruding fleet from there.

I agree fighters can use something to help them close the distance. At 400" per turn they are looking at 30 seconds to close for each kilometer. At 1,000 km they will never reach their targets before everyone falls asleep.

 

A vacuum booster that gives them x8 NCM or more might do the trick though.

What is a "vacuum booster"?

I thought about the fighters, though- in a widely spread formation, they are more capable to withstand a space nuke as a squadron than a larger spaceship the cost of a aquadron is.

Fighters would have to be built with a similar fusion drive as the larger ships, though- and maybe about the same delta-v. _If_ one assumes that those fusion drives can be built in such a light way that high-thrust-fusion drives are possible, that is.

Re: Things that are cool about Alien Wars

Another thing I liked about Alien Wars was the well detailed military hierarchy and structure. Firmly based on common current-day hierarchy and structure' date=' to make it believable, simplified some to make it easier to play. A definite for that.[/quote']

 

I agree, the given structure is detailed and believable, both at the beginning of the war and at the end.

However, current-day military hierarchy and structure on this planet are a lot more diverse, naturally,

 

The endless stupidity of he Logistics Computers is, sadly, very believable too- large organizations tend to loose contact with reality all the time today, and for a military force without any real wars in the last centuries, this seems even more true. Dramaturgically, the LC's are cool, too- incompetent superiors obeying incompetent computers allow for a lot initiative on the part of the PC's.

Re: Further thoughts about the UES Centauri and the AW space combat environment

I try not to mix too much from Star Hero into AW/TE. It seems that the official world has its own take on how it wants to do things and seems to side-step both SH and TUV most of the time.

Well, in the case of AW, this seems to be rather unintentional. It obviously tries to be hard science where that is applicable.

I remember the Hydrogen Scoop from a 20 year old NASA project

Do you have a name or link on that? That'd be cool.

I know your concern is more about vehicle combat but that aspect really does not bother me that much. With the ranges on the ship's weapons they really don't need to get that close.

Well, encounters usually start at a minimum of 100 000 km. Effective weapon range is about 3000 to 5000 km (or is it?). There's a lot of maneuvering one could do to avoid an opponent whose delta-v is a bit scarce...

Hm- I'm thinking about the role of space fighters in such an environment. Do they make sense?

Re: Further thoughts about the UES Centauri and the AW space combat environment

I would equip the starships with a retractable hydrogen scoop on the front. This scoop would suck up hydrogen molecules and convert them to propellant.

The available hydrogen in space is not that much, though. And that scoop would have to be very big. Star Hero mentions those Bussard ramjets and what their problems are on page 190.

Re: Further thoughts about the UES Centauri and the AW space combat environment

I'm not that familiar with the AW setting' date=' but I do have Star Hero. Just curious, but in the scenario you described how close would the 2 sides be when they started shooting at each other?[/quote']

 

Well, the Centauri uses Lasers that have MegaRange, 1" = 100km. Same is true for the Xenovore ships. If we assume the crews are rather realistic people, I'd assume they would have to wait/miss until the targets are within some 3200 km or so.

 

Edit: Oh, and relative velocities for an intercept maneuver would probably be well above 10 km/s, while accelleration and decelleration are done with rates of 5-15 m/s^2.

Re: Something Star Hero needs, but hasn't-PT2

if you want ship deck plans there are several out there.

Next thing you tell me is that there are other SF settings out there that I could buy.

Re: Something Star Hero needs, but hasn't-PT2

Well' date=' what is stopping us from making our own deckplans? [/quote']

 

Probably the same thing that is stopping us from writing our own RPG system, our own RPG setting, our own ...

Re: Things that are cool about Alien Wars

I vaguely recall that scifi story (SDI that is )...

Well, those technical problems don't seem to be unsolvable by principle:

http://repairfaq.ece.drexel.edu/sam/laserioi.htm#ioixrl

Re: Things that are cool about Alien Wars

X-Ray' date=' definitely beyond our current tech. I wonder how you can reflect the rays to make them uniform? [/quote']

 

A lense from a material that works for X-rays like crystals work for visible light. X-Ray lasers were considered in the US 1980's SDI project, so the technical problem seems to look solvable at least to some people, without using rubber science. Since AW is in the 24th century, I assume they were solved at some time.

Re: Average Seperation

Does it mention any trend as to the types of stars that have planets?

You'll probably find tons of info about that on the 'net. One thing, though: the as-yet-detected planets are almost all of the gas giant variety. AFAIK, only one "terrestrial planet" (which means "a ball of rock") could be located, and they're not sure whether it is that or just a very small gas giant.

The problem with detecting extraterrestrial planets with curent technology is that one cannot spot them directly with a tetelscope or something- they simply look at the star and try to see when it is dragged a tiny bit towards a direction were it douldn't be dragged, thus assuming that there must be some planetary body whose gravity well draws thestars towards them. The exact size of that (_very_...) tiny bit tells the astronomers how large and heavy the planet is. Humanity will need a lot better telescopes for directly spotting extraterrestrial planets.

Well, I could not resist to think more about the Centauri's propellant problem.

First, I thought "Okay, it is flight, not cumulative flight, so they'll probably just spend lots of time in free fall." Space battles thus wouldn't be too exciting, but at least it could work, I thought.

However, they want to be in orbit around an Earth-sized planet and want to make Hyperjumps from there. The Hyperdrive requires "a distance of about a hundred thousand kilometers" from an Earth-sized world, which means essentially leaving orbit. But to do that, one needs escape velocity- 11.2 kilometers per second. The Centauri with chemical rockets, however, could not hope to carry anything but propellant and manage to reach that speed at the same time.

So the obvious solution is another drive, probably a thermal fusion rocket. I am a bit optimistic, so I assume this one has an impulse of about 100 000 seconds, or an exhaust velocity of a about 1 000 000 m/s.

That way, our battleship could use only one-third of its 100 ktons of mass as propellant (leaving about 65 000 tons to the actual ship) to have a delta-v of 20% of its exhaust velocity, which means a delta-v of 400 000 m/s or 400 km/s. If it burns all the propellant, which it won't, of course. (100 ktons initial mass divided by 65 ktons final mass is about 1.5, ln of 1.5 is 0.4)

This "new and improved" Centauri could accelerate to escape velocity and a bit more, say, 20 km/s, proceed in free-fall to the jump point 100 000 km away (which takes it 5000 seconds, or just below one and a half hours), then jump, decellerate if necessary, accellerate into the other direction again to reach a close orbit, decellerate again, and fight its way through enemy ships. It would then have used up about 20% of its propellant.

That's probably as good as it gets with hard SF assumptions. Since we know that Xenovore ships are not far superior to Terran ships, this is probably also close to the technical limits of their dreadnoughts as well.

Now what would that imply for ship combat tactics?

Most of the time, one fleet will jump into the system, then accelerate (having decelerated before the jump) towards the target planet, where the defending fleet waits in orbit. Detection is absolutely no problem for both sides, since the energy required to power such large ships will be detectable pretty easily via infrared.

Intercepting the incoming fleet would not be smart, because that would mean to burn lots of delta-v to get some velocity, then decelerate (with the drive pointing towards the enemy, and no, no Kzinti lesson is applicable here) to match enemy's velocity about the time when the fleets meet each other in space and "escort" the attacking fleet back- if your ships are still in fighting condition after the decelleration maneuver, which the enemy would doubtlessly use to attack you while you can't shoot back accordingly.

The defending fleet might manuver a little in orbit, but given the available acceleration rates and delta-v, they won't be able to "evade" any attacks. That means the two fleets will be mindlessly shooting each other, since outmaneuvering is simply impossible. Space combat will thus be a rather boring "who hits most first" excercise.

Is this true, or did I overlook anything?

Re: Things that are cool about Alien Wars

However - there is a HUGE drawback.

How much smoke is there on the average battlefield? It's a bit much to assume that both sides don't use combustion engines, explosives or smoke grenades...

I'd give everyone a projectile sidearm as well, just in case.

IIRC, those rifles were Xray-Lasers. So smoke is not that much a problem.

Re: Things that are cool about Alien Wars

It's not listed AFAIK (I only bought Alien Wars yesterday and have only skimmed so far) - but squad support rechargers would make sense. The big problem with nuclear is the shielding, of course - which is the majority of the weight.

Well, the setting knows "cold fusion reactors". So not much shielding required.

Well, while there is this certain problem with the setting I mentioned earlier , there are lots of cool things about the setting. One thing I just wanted to point out: Laser rifles.

Now there is a real reason why a modern army should have those. The Laser rifle is a large military's wet dream: While it is not as efficient as a conventional slugthrower, its ammo ist just a few hundered thousand times easier to obtain. That was an idea I had never encountered before, at least not for infantry weapons and it is the most plausible reason for using personal energy weapons I have seen.

Just reread that part and felt the urge to say that. Thank you for your attention, citizen.

Re: Something Star Hero needs, but hasn't-PT2

There are so many web resources for ship deck plans that in the long run I don't think the lack matters.

True, but 1) Terran Empire an Alien Wars would really profit from a deck plan book as proposed (setting-feeling-wise) 2) there's probably "a lot" (as far as SF RPG's are concerned...) of money-earning potential in such a product, because while one can use foreign setting deck plans with AW and TE, the other way round this is also true.

Plus, the ships from Jovian Chronicles are virtually the only ones with deck plans and spin gravtiy AFAIK... and there are not that many deck plans of them

UES Centauri and UES Jupiter deck plans, now!

Re: Usning nanotech in a campaign

Does anyone know how feasible (assuming hard science) it would be to use nanotech to synthesize liquid hydrogen or oxygen that would remain somewhat stable at STP (Standard Temperature Pressure)?

Well, not too much. You'd have to give your nanobots lots of energy to force the gas molecules together. It'd be much cheaper and simpler to cool the gas.

Nanotech is not an all-powerfull super tool, it would probably not even be very competititve against more conventional means for many tasks, such as metalworking. It cannot change he laws of physics, either.

Re: Something Star Hero needs, but hasn't.

OK, here you've lost me. How does using XDM lead to quadratic equations? And your bit about larger distances and travel time and maps I just cannot turn into English I understand.

If you have a reactionless thruster (such as in later TE times), you can accelerate all the time. Now, if your Hyperspace drive works as described in AW und TE, you will accelerate in Hyperspace also (only 1 m/s in Hyperspace will equal 1 000 000 m/s in normalspace).

T is the Time required (in seconds), V is the average velocity (in megameters per second), A your acceleration (in m/s/s)

T= D/V

V= A*T/4

So your travel time is:

T= D/(0.25*AT)

D=0.25*A*T^2

4D/A=T^2

T= [4*(D/A)]^(0.5)

or

T=2*[(D/A)^(0.5)]

Thus, the travel time is not proportional to the distance. A twice as high a distance requires not twice as much travel time, but less. To most people, that does not feel right, and it requires computation that most people aren't used to.

Re: Alien Wars: Before hyperdrive, there was...

Uh' date=' I hate to rain on your parade, but by what mechanism is the excess velocity "bled off"? It's not like they're in an atmosphere where they'd loose velocity due to friction...[/quote']

 

Well, friction is the cause nevertheless. Interstellar space is not as empty as it would seem- it has, indeed, a very, very, very, very thin "atmosphere" of hydrogen and other gases. That does not matter normally, but when moving at the speed of light...

Re: Something Star Hero needs, but hasn't.

I disagree. The fact that a ship in Hyperspace is undetectable, but that two (or more) ships in Hyperspace can interact, combined with better Hyperdrives letting one stay in Hyperspace longer leads me to think that the Power that best models this is Extra-Dimensional Movement.

D'oh! Of course!

Still, with all the work put into the existing stats in AW, TE and SpT, I would prefer simply changing the rubber science explanation to "shunt into another universe which moves (maybe: "rotates"?) at superluminal speeds relative to our own, stay there for a while being dragged, then return when desired". Higher class hyperdrives would allow to shunt into even faster hyperspace universes. (If you like the idea, feel free to use it at no cost. )

After all, using quadratic equations for all interstellar travel could really bog down a game... and the effect of larger distances being not as far away in travel time as is showed in distance on the map is rather un-intuitive.

Re: Alien Wars: Before hyperdrive, there was...

Such a drive would not become obsolete for STL! If there's something that can accelerate to 0.5c or higher, at a reasonable cost (in money, energy, propellent or lack thereof), there would be utterly no reason to abandon it.

Well, it could have been a drive that was of very high impulse, but very low thrust, allowing for accelerations of 0.01 g (0.1 m/s^2) or even less, but for a very long time with a given propellant mass. That would make it useless for tactical or short-term operations, but quite valuable for interstellar travel at STL speeds.

Re: Alien Wars: Before hyperdrive, there was...

Now, one could assume the Colony Act created the concept "Senate Worlds", even though there weren't any,

That's not correct. There was at least Earth.

Suggestion: The Colony Act was actually some kind of political maneuver to achieve some completely different, more day-to-day buisiness-like thing which is now long forgotten. "By accident", it was also a document that allowed for the legal concept of "more than one Senate world", because until then, there was only one world allowed to send senators, and that was Earth, of course. (For example, the real idea behind the Colony Act and a few related documents that in effect changed the UE's constitution could have been to install a new office: That of Earth's senator, who would have been quite powerful given the fact that he was the only one...no one of those who passed the Colony Act really believed that there could ever be a real "Senate" with many Senators.)

Re: Something Star Hero needs, but hasn't.

And instead of the Ultimate Starship they added the FTL flight power to the rules to custom build vehicles.

But it doesn't do that. You cannot "build" a starship with Hero System. You can only *describe* its abilities in game terms and assign a point cost (which is usually rather useless for a spaceship in a campaign where these are regularily bought and sold).

Re: Something Star Hero needs, but hasn't.

2) from Alien Wars p.125, repeated in Terran Empire p.158:

"Trvel within Hyperspace depends on two things: first, a ship's normal propulsion (since the ship has to propel itself through Hyperspace);..." Thus, the whole matter of propellent mass fraction applies to FTL as well as STL.

 

Frankly, I don't think the writer thought things through at all.

Yes, I noticed that too. I decided for myself that the rubber science explanation of hyperspace and the Hyperdrive are wrong, and the stats for the hyperdrives given are correct- both is not possible. OTOH, since the stats for the ships giving would need a rework in the light of what has been shown, maybe one could correct this too in the 2010 "revised edition" of Alien Wars...

I believe for actually mapping the described hyperspace physics one would have to buy the Hyperdrive not as Teleportation, but as normal movement plus Megascale and ignore "not for FTL" rule on that. The STL drive would have to be another one- possibly an antimatter drive of some kind, or maybe a "particle accelerator neutrino drive" (which would have the convenience of not being a _very_ potent weapon, since neutrinos are harmelss particles).

Now that's maybe actually an idea: Building a particle acclerator of high output, powering it with a fusion reactor, and using it as a drive. Based on current technology, it would be very low-thrust, of course, but advanced versions might become better at that too. The impulse would be near light speed. Of course, one would have to miniaturize particle accelerator technology, but that is not completely unthinkable...

Edit: Oops. I just reinvented the ion drive. Sorry

Re: Something Star Hero needs, but hasn't.

When setting up a science fiction campaign, a GM needs to keep one foot based in real science to maintain believability but is eventually faces the need to bend or break the laws physics to make their campaign to work. The creators of most of the successful science fiction franchises such as Star Trek, Star Wars, Babylon 5, Firefly, etc. bend or break the rules of physics at some point or another to make their universes work. The suspension of believability does not seem to stop us from watching these shows or finding inspiration in them.

But that's TV, and thus a different medium. RPG as a medium of storytelling is a different thing and has different requirements, since it has not the all-powerful author to make the epsisode work. Players of an RPG need some base for their imagination and planning. If they have to solve the problem of aquiring, for example, enough propellant for their spaceship to reach starbase X, they need some background about "what" and "how much" of it. With said Centauri, they'd run into a problem here... a problem that could blow up the entire gaming session if the group cares for such details (and they play hard military SF, so they probably do).

In SF, you have lots of equipment, but the story should be the story of the characters. In order to give them something to act, you have to give them a coordinate system to act within.

Besides, there are not that many attempts to make a hard sf TV show, so we have no choice but live with those that are there, even while being annoyed by a lot of details. The new Battlestar Galactica series seems to be the first attempt on hard SF TV. And it is really an order of magnitude better than the others...

When setting up the tech level for any campaign, a little common sense goes a long way when defining the stats for vehicles or gear but in a multi-genre book such as Star Hero, a defined "Build System" would not work. The strength of Star Hero is its wide appeal. In games such as Traveler, which have a defined "Build System," they are a unique settings and do not translate well over into other genres. [...]

Actually, the known-science-parts of the Traveller constructon systems (hull masses, for example) are quite universal. The differences between settings lies in the rubber science parts.

As long as the setting in question is well-thought through, of course. There is lots of bad SF out there, where the technological and super-scientific assumptions don't make sense within themselves at all.

Re: Alien Wars: Before hyperdrive, there was...

It'd also be a ***** to store! It would be dangerous in the extreme, be subject to "shrinkage", etc.

There ain't no such thing as a free lunch.

Also, the "antimatter photonic" rocket idea (advanced by Eugen Sänger in the 1950's) is unworkable. The current thinking is to use antiprotons only, and either "channel" the pions produced when they interact with protons, via a "magnetic nozzle", or to use the interaction to heat a propellent (such as hydrogen, water, methane, etc.) and have that "fly out the back". Either one means a noteworthy amount of propellent.

How can this be for the former? The latter, okay, sure. But simply redirecting the pions should not require any additional propellant?

BTW, according to The Starflight Handbook, for anitmatter rockets (for use in the Solar System, mind you!) to be feasible, the cost of making antiprotons has to come down to ~$10 million per milligram, and the current (1989) cost is $100 billion per milligram.

That is something a revolutionary energy source like fusion power, combined with new, better techniques of producing antimatter and a reason to do so on a large scale could actually do.