Spaceship launch

[AlanH]

On my first game using civ2/3 rules, and reached the point of being able to launch my spaceship. However, although the odds are 100%, it's short of 4 modules. The time it will take is 11.9 years.
What to do? Launch, or build the missing 4 modules to get a swifter journey?
I chose to build the 4 modules.
Mistake.
The spaceship (complete) will now take 15 years. Still 100%.
This has to be a mistake. Surely, a complete spaceship should be making the fastest journey? Am I missing something?

[cazfi]

It's heavier with the additional modules, so it's slower if you have the same number of engines to provide the thrust.

[AlanH]

Lighter, yes, but also riskier. The chance of success should not be 100%.

[Rudolph Lucas]

Lighter space waves free, yes, but also riskier. The chance of success should not be 100%.

What method must we choose to achieve 100%? Have you tried a better method?

[NotTired]

I found a suggestion for the optimal strategy for launching a space ship to Alpha Centauri many years ago. I've used it ever since, and it's never failed. The "Chance of Success" means the odds that you'll get to AC before anyone else. if nobody else is even trying to get there, your odds are pretty much 100%. It is thus important that you keep your plans to yourself, lest another player tried to get there first.


Building Space Ship
Requires three parts for space flight: Structurals, Modules, and Components.
1) Research Space Flight Technology.
2) Build the Apollo Project Wonder – can’t skip this!
3) Research Superconductors and Plastics.
4) Build the following Units, in the following order:
a. three Space Modules (requires Superconductors)
b. 16 Space Components, two or four at a time (requires Plastics)
c. 21 Space Structurals. No advantage to building more.
They need NOT be built in the same City, and need not be transported to one City.
If the Units are built in any City, they are put together automatically.
5) Observe construction progress by tapping [F12] to get to the Space Race Page.
6) Launch Ship by clicking the [Launch] Button in the lower right of the Space Race Page.
7) View the expected Turn of arrival at Alpha Centauri by tapping [F12]
8) After eight more Turns, you win!

[taifo]

I found a suggestion for the optimal strategy for launching a space ship to Alpha Centauri many years ago. I've used it ever since, and it's never failed. The "Chance of Success" means the odds that you'll get to AC before anyone else. if nobody else is even trying to get there, your odds are pretty much 100%. It is thus important that you keep your plans to yourself, lest another player tried to get there first.


Building Space Ship
Requires three parts for space flight: Structurals, Modules, and Components.
1) Research Space Flight Technology.
2) Build the Apollo Project Wonder – can’t skip this!
3) Research Superconductors and Plastics.
4) Build the following Units, in the following order: شركة نقل عفش شركة نقل عفش بالطائف
a. three Space Modules (requires Superconductors)
b. 16 Space Components, two or four at a time (requires Plastics)
c. 21 Space Structurals. No advantage to building more.
They need NOT be built in the same City, and need not be transported to one City.
If the Units are built in any City, they are put together automatically.
5) Observe construction progress by tapping [F12] to get to the Space Race Page.
6) Launch Ship by clicking the [Launch] Button in the lower right of the Space Race Page.
7) View the expected Turn of arrival at Alpha Centauri by tapping [F12]
8) After eight more Turns, you win!

Hey, thanks for the tip! Followed your strategy and it worked great, made it to Alpha Centauri without any issues. appreciate your sharing!

[Dino the Dinosore]

You can build space ship parts in any order. I usually build 6 Components, which then need fewer Structurals (maybe 15?). Once you start building any space ship parts the AI's all instantly know about it and will become more hostile.

[najarq8]

Yeah, it’s a common Civ2/3 quirk only engines and propulsion modules affect travel time. Adding extra (like habitation) increases score but can slow you down. Launching earlier with fewer modules is often faster

[John Campbell]

So I just went and poked around in the spaceship code, and the way the spaceship actually works is:

The "chance of success" is not your chance of getting to Alpha Centauri first. It's your chance of getting to Alpha Centauri at all. (Though if you're playing single-player, that's pretty much the same thing, because the AI has always been completely incapable of building a spaceship, and civ2civ3 has only made that worse .)

The minimum functional spaceship is two Space Components (an engine and a fuel tank), three Space Modules (a habitation module, a support module, and a solar panel module), and eight Space Structurals to connect them all together. If you have less than that of anything, your chances of success are 0.

Every habitation module needs at least one support module. Every habitation or support module needs power, and a solar panel module can power two other modules. So if you have one of each, your habitation module has support from the support module, both of them have power from the solar panel module, and you're all good. 100% chance of success. And if you keep adding them in sets of one of each, you're good.

The problem comes when you don't have the same number of each type of module. If you have more solar panels than you need for the number of habitation and support modules you have, it's not a problem, you just have excess power. If you have more support modules than habitation modules, as long as you have enough solar panels to power them, it's not a problem; you just have redundant support. If, however, you have more habitation modules than support modules, you have a problem. You don't have enough food and air and so on for the number of colonists you've got, and there's a chance they won't all make it. If you have more than twice as many habitation and support modules, combined, as you have solar panels, you have a problem. You don't have enough power to power the whole ship, and there's a chance that things will fail and your colonists won't all make it.

The chance of success is figured by the formula:

[(S/H), max 1] * [(2*P/(S+H)), max 1]

Where S is the number of support modules, H is the number of habitation modules, and P is the number of solar panel modules.

The computer makes the decisions about which kind of Space Module and Space Component to place, and where to put Space Structurals. It always builds Space Components in pairs: one fuel tank, then one engine. It tries to place Structurals as necessary to connect parts that already exist, prioritizing the first three Modules (the minimum needed for a functional ship), and then the engines, and then other Modules. Space Modules are more complicated. The code includes a comment that

Code: Select all

     
     /* "nice" governments prefer to keep success 100%;
     * others build habitation first (for score?)  (Thanks Massimo.)
     */

However this does not actually appear to be the case. Government type isn't checked at all. If I'm parsing the logic correctly — it's an ugly, tangled mess that keeps flipping logic senses and gratuitously overuses the C ternary operator — everyone builds habitation, support, then solar for the first three Modules, then solar panel, support, and habitation thereafter.


Travel time is simpler. It's determined by the mass of your ship divided by the thrust your ship produces. Every ship part has mass. Only engines produce thrust. Adding engines adds more thrust than it does mass, so it speeds you up. Adding anything that is not an engine adds mass but no thrust, and will slow you down.

However, you need parts other than just the engines for the ship to function at all. Each engine needs a fuel tank, which doesn't add thrust itself, but is required for the engine to generate thrust. You need at least one habitation module to carry colonists, at least one support module to keep your colonists alive, and at least one solar panel module to power the other two modules. And you need enough Space Structurals to connect everything together, because if it's not adjacent to a Space Structural, it's not actually part of your ship, even if you can see it in the ship tab. It's just floating in space next to your ship.

So if you want the fastest ship, you should build just three Space Modules — one each habitation, support, and solar panel — then build Space Components until you can't build any more (16), and then Space Structurals until everything is connected (should be 20).

If you build a "complete" ship, with all 12 Space Modules, all 16 Space Components, and all 32 Space Structurals to connect everything, it'll be slower than the minimum Module/maximum thrust ship, but it'll have more colonists, so it'll be worth more points.

[Dino the Dinosore]

Wow John, that's an awesome writeup. Could you add it to the wiki?
http://www.freeciv.org/wiki