Starships as Giant Armored Air/Rafts

[Fred Brackin]

Originally Posted by Curmudgeon

I missed the Lifting Body with Excellent Streamlining part, which does change the Stall Speed, however your figure is not quite correct (and should according to Vehicles be rounded to 500 mph). Excellent streamlining makes Sl=1.2 instead of 1, which raises the stall speed and is why I went with Fair Streamlining initially t.

I included the 1.2 factor for Excellent Streamlining. It's mandatory for any air vehicle that's going to exceed 740 mph. See the table of mopdifiers on p.135.

As for stall speed being relevant it's only so for vehicles without Vectored Thrust which is another thing all G:T ships are built with.

G:T ships can not take off and land like airplanes so there's no reason they should be limited by stall speed in forward flight.

[Curmudgeon]

Originally Posted by Fred Brackin

I included the 1.2 factor for Excellent Streamlining. It's mandatory for any air vehicle that's going to exceed 740 mph. See the table of mopdifiers on p.135.

As for stall speed being relevant it's only so for vehicles without Vectored Thrust which is another thing all G:T ships are built with.

G:T ships can not take off and land like airplanes so there's no reason they should be limited by stall speed in forward flight.

A minor point: according to GURPS Traveller: Starships (p. T:S28) the standard for starships with streamlining is very good streamlining and a lifting body, not excellent streamlining and a lifting body.

Okay, stall speed is off the table due to vectored thrust, but this then introduces a new question. Can a reactionless drive vary its output? If it can, then OP's problem becomes much more pointed, but if a reactionless engine only has the choice of maximum output or none, then it can't travel at less than it's air speed and a vessel travelling at 2,357 mph has perhaps 10 seconds to detect and react to something about man-sized before the curvature of a earth-sized planet takes it out of range.

We may be getting into minutia at this point. Broadly, my response to the OP's problem is: maybe spacecraft just can't go slowly enough to make the perceived problem a practical one.

[Fred Brackin]

Originally Posted by Curmudgeon

Can a reactionless drive vary its output?

If it can't vary its' output landing becomes extremely dangerous as the ship can only have the drive on at full power or not at all. This problem gets worse if the drive won't cycle on and off instantly. Then there are the small adjustments to thrust needed for planets have that have more or less than 1G gravity.

You ca ahve problems with ships because they are much biogger than air/rafts or ground vehicles. The art doesn't really agree but mass makes a Free Trader as large as a 747. Even with full VTOL it couldn't land in most forest clearings. Flat places in mountainous terrain might be even mroe limited.

Then there's possible exhaust problems. Even if exhaust is no worse than a jet engine's that still lets out most grasslands and forests though ti won't matter in the desert, wastelands and mountains.

Exhaust in the form of other problems such as radiation and/or EMP would keep ships limited to tightly controlled flight paths on inhabited worlds though the "big as a 747" thing probably already does that.

[Infojunky]

Originally Posted by David L Pulver

In various Traveller adventures, starting with early GDW ones like Mission on Mithril but continuing the present day, there is often the assumption that their ship lands on an exotic world, and the crew exit to explore, map, hunt, or otherwise travel via ATV, open air/raft, or afoot across dangerous terrain, across the GM's detailed planetary hex maps while experiencing the perils of random alien animal encounters, local malcontents, and/or planetological events.

Ok, in CT, early on the assumption was ships used some sort of Fusion Drive.

As such most of the early adventures reflect that.

Originally Posted by David L Pulver

, with spaceships generally being defined as vehicles possessed of reactionless/gravitic drives with thrusts usually in excess of the average planets (size 5 or so) gravity (especially if you have a scout ship, fast trader, pinnace, etc. with 2G+), the cunning player may well ask why they can't (when visiting X-class starport worlds or those of a low TL) just do their exploring or mapping or hunting by having their antigrav drive ship cruise along at walking to airship-like speeds just above the treetop, in perfect safety (as most ships are armored to resist 250-megawatt laser cannons) as a mobile base in comfort. Sure, they'll need to get out when they get close to interesting wild life or alien ruins or whatever, but that's far less dangerous and faster..

After Striker/MegaTraveller this was more the case.

Really it comes down to what flavor of Traveller you play. In which the adage "We all play Traveller, but every Traveller game is different"

In my games the Fusion Drive is the standard, but I have been running Traveller since 1st edition.

[Rupert]

In my game, as it's set in the New Era and most worlds are lacking starports, the players were often in this situation.

They started out by orbiting for a while to get a map and check it against any old map they might have, assess current settlements, technology, and so on.

If they needed to refuel they'd land somewhere as isolated as possible and do that then move onto the main objective...

Then they'd land as close as possible to interesting looking sites and go in looking for stuff to salvage (or sometimes steal).

After a while, and several times when locals better equipped than expected caused damage to their ship, they moved to landing about a half-hour's flight away by air/raft and flying in on them.

This was encouraged by their later ship being a tail-lander without contra-grav, so it had only two in-atmosphere flight modes - 'landing/lift-off' and 'rocket'.

Finally they moved to leaving the ship in orbit (their last ship wasn't atmosphere capable), going down in a cutter, and launching air/rafts from it as it overflew the area of interest, and then having the cutter either orbit above any cloud layer or fly off and hide.

Due to doing all this with a fairly small crew, the later, more paranoid procedures actually made matters worse for them. Everything took longer, and they had more people spread over more vehicles, with fewer crew available to do the actual work. More vehicles and more crew flying them also meant more assets that were vulnerable should anyone attack.

[Rupert]

It occurs to me that aside from Imperial and local regs, the likely clumsiness of massive starships making flying low and slow a bit fraught, and all that, there is one other factor.

Yes, the locals might not be able to make a hole in your ship's hull, or even dent it, but the ship probably has a whole lot of stuff that's outside the hull. Radio antennae, navigation and landing lights, and so on. Now it'll be mostly under fairings but they'll be fairly lightweight on a civilian ship, and the important stuff will have redundant components, etc., but if the players want to keep that redundancy (and not get pinged by starport traffic enforcement for having tail-lights out) they'll need to replace these parts if the locals manage to tag them with some field cannon or the like and smash this stuff up. Unless they've got a sweet 'all operating costs and damages met' contract with their patron, that'll be coming out of their profits. If other people's players are like mine, this'll be a fairly strong incentive to not put their spaceship where it can get the paint scratched.

The trick will be to get the risk level right so they don't see dinged tail-lights on their ship as better than shot-down air/rafts. This probably means attacks that can smash up the surface features of a spaceship but not easily wreck an air/raft. The air/raft being a smaller, more agile target will help.