Thanks for the rephrase.

I think this comes down to one of the differences between the story telling approach and the simulation approach. In the story telling approach you have a need for a specific thing to happen, and configure the universe in such a way to make it likely to happen (a anti-air weapons team is x km from the spacecraft = 1 point of damage). In the simulation or more typical wargaming, you have the universe "the way it is" but the outcome is uncertain (a anti-air weapons team is 3.61 km from the spacecraft = x points of damage). In simulation you have to keep track of the opposing forces and make their actions plausible, even when those actions aren't visible to the players. In story telling you don't have to keep track of anything, the opposing forces are in whatever disposition they need to be at any given time for the story telling elements to occur.

From a strictly simulation point of view, given my own perception of TL6 anti-air technology, there are only a few ways to make a hit plausible:

1) It is an antitank rocket fired at close range (<300 meters) just as the ship is lifting off. Even a couple of seconds after lift off an antitank rocket won't be able to catch the accelerating ship, but if there is a hit it could do damage that would need to be dealt with, like a small hull breach that needs to be patched to be vacuum ready.

2) It is man-portable air defense fired at up to medium range (<2 km) within the first 20 seconds or so after take off. A hit is possible but the warhead is small enough to not do significant damage to the ship.

3) It is theatre-wide air defense or anti-ballistic-missile defense (Soviet S-300 or Russian S-400 like systems). This could be fired probably up to a minute or two after the ship lifts off (I'll simulate it later to get better than "a minute or two" later) from even dozens of km away, and the warhead is large enough (or it is a kinetic energy impactor with enough velocity) to do significant damage to the ship, but that system isn't man-portable. It'd be launched from a road-mobile or fixed-position air defense site. You an get an idea of what S-300 launchers look like here: https://en.wikipedia.org/wiki/S-300_missile_system and an exoatmospheric intercept might be possible.

In the first two cases, once the ship is underway it doesn't have to reach orbit or get out of the atmosphere with any particular urgency - it could hover at 25,000 meters altitude while determining what action to take and it would not be vulnerable to anything man-portable at TL6, but if the opposing force can command national air defense systems (such as system #3 above) the ship should not dawdle at any altitude and it's best to put a quarter planet diameter or more between you and them.

From a storytelling perspective, I wouldn't worry about the nature of the opposing force, it's plausible from story telling, if not simulation, that a rocket fired from the ground could hit a ship - just don't get into the distances between the ship and launcher or the current ship's altitude.

-------- Original Message --------

On February 9, 2018 8:24 AM, Timothy Collinson <xxxxxx@port.ac.uk> wrote:

On 9 February 2018 at 08:51, Caleuche <xxxxxx@sudnadja.com> wrote:

I just realized that the players were on a ship on the ground, just how far is the SAM away?

Well that was one of things I meant to ask...

It's actually quite a precise distance. It equals exactly whatever is required to give them the best chance of doing *some* damage.

Let me reprise the scenario as it's probably lost early in the thread.

PCs hacking through the woods/forest to find a mining camp in the mountains "near" which Bannerji's ship is hidden. His ship is a Far Trader (so 1G).

The PCs *should* be getting aboard the ship with Bannerji's help *maybe* after he's tried to have them killed by miners (or the rest of his crew) at the camp. He'll still want to get offworld with his broken leg and all and will claim that only he can input the access codes.

PCs, Bannerji and any (surviving?) crew take off for orbit and think they're safe from the ground troops who've been chasing them through the forest and/or hunting them with OH-1A style helicopters, or perhaps a Huey style thing.

Some of those troops, nearly caught up (or possibly someone from the mining camp - I need to reread the last bit of the chapter Wolf at the Door), take a shot at the Far Trader as it takes off, or very early in it's flight with SAM or RPG I think someone suggested (I assume they're ok at TL6).

I *don't* want ship (and PCs) blown out of the sky but scared maybe by first shot and perhaps hit by a second shot (I will probably let dice decide this... there may be a third shot!). Hit such that there is a little bit of damage such that it would require exciting piloting/engineering/medic rolls to get to orbit safely and finish the chapter with a bit of a climax.

Does that sound like a plan?

(Also debating having Bannerji with the foresight to have converted one of his passenger cabins into a fully featured med bay [1] and then allowing one of the PCs in the 'departure firefight' to be *really* seriously wounded, near death, but able to be saved because of the medbay which I don't think they'd be expecting.)

I tried out this situation: https://i.imgur.com/XpRIJe3.gifv

SAM is fired at the same time that the ship (a to-scale 800 Dton sphere) launches. Units in meters. The ship can accelerate at 1g in vacuum, and the missile has a SAM-like flight profile, it has about 30 seconds worth of thrust.

The ship launches at 1g, at 1.5s realizes it has been fired on and cuts power for 1s, hoping to confuse the guidance system on the missile or that the missile is unguided, and restarts with full power at 2.5s.

Missile impact is at ~9.9 seconds.

I tried a couple of variations on this, with the anti-tank-like performance profile, the missile can't hit the spacecraft unless it's launched from a very close distance (300 meters or so) or before the ship launches.

OK, baddies at less than 300m. No problem.

1g acceleration actually feels quite sluggish at this scale, compared to missile performance. If I can find performance information for the Russian S-400 SAM/anti-ballsitic-missile system, I'll put that together too and see if the ship can be threatened from a much further distance.

cheers

[1] And of course, for those who read the write up, was one of the options *they* could have installed in one of their own cabins if they'd chosen not to upgrade the air/con. :-) So nicely foreshadowed (by accident).

(My idea with the medbay installed is that it would help PCs who need such help, but they'd also get bonuses on passengers who want to travel with them.)