Spaceships in the sky -- how do you handle spacehsips flying?

[manley_t]

Do you guys do the Star-Wars/Star-Trek of the magical hover/VTOL or do you say that the maneuver drive only provides thrust and either the ship lands based on that thrust (i.e. on it's tail) or it lands like a plane?

In most of the games I've played in the past ships behaved more akin to the way they do in Star Wars. Spaceships could land and take off veritically, even though their engine orientation was still aft. We just 'assumed' that the 'magical technology' of the maneuver drive allowed it to behave so.

But, if you want to take a hard-tech line and you say that the maneuver drive provides thrust only then you have to make amends for how your ship lands and takes off.

What do you guys do?

 

[Father Fletch]

Contra Grav and Thruster tech allow Star Wars style take off and landing. This allows even large, unstreamlined ships to enter atmosphere, but at no more than 200kph. YMMV

 

[manley_t]

Do you require that contra-grav be installed on the ships when they're designed then? Or do you have the Maneuver Drive able to handle that?

 

[BigBadRon]

The drives ARE contragrav, or thruster plates at higher TLs, which means the direction of the ship's flight is not determined by the orientation of the drives.

 

[Uncle Bob]

CT maneuver drive does not have a specific direction of thrust, so it can act as a "magic" hovering drive. Of couse, 1 G drive still isn't enough to land on most planets and streamlining is an issue on worlds with atmosphere.

 

[BigBadRon]

Originally posted by Uncle Bob:
CT maneuver drive does not have a specific direction of thrust, so it can act as a "magic" hovering drive. Of couse, 1 G drive still isn't enough to land on most planets and streamlining is an issue on worlds with atmosphere.

However, a streamlined (more specifically, an "airframe" configuration) ship with a 1 G drive can still land or lift-off like a conventional plane, and will reach orbit eventually. Time isn't a problem because a vessel with cg or thrusters doesn't run out of fuel.

 

[manley_t]

And this makes Maneuver Drives different than the gravitic engines on vehicles how?

These explanations tend to tell me that you guys are playing them as the same, yes?

 

[BigBadRon]

More or less, yes.
I tend to think of ships drives as being more robust, designed to run for longer periods at one time than normal vehicle systems, and optimised for space travel.
But apart from that I don't think there's much difference between them, not in terms of game effects anyway.

 

[Golan2072]

::casts "Ressurect Dead Thread"::

IMTU, the cost of streamlining includes the cost of small, hydrogen-burning (chemical, ofcourse, not fusion, leave that for the main drive) turbines for atmospheric flight. Don't use much fuel, and are quite slow (in space terms, that is), and require atmospheric oxygen, but let you use VTOL and low-speed flight in the lower atmosphere. In a non-oxygen atmosphere, or on a vaccum world, or when you want to get off-planet FAST, you just ignite the main fusion drive (manouver drive) and ride it to orbit. Most big spaceports support this mode. but it isn't very good for near-terrain manouvering and close air support.

 

[BetterThanLife]

Everything I read says they are different in only one respect. Maneuver Drives have Thruster plates and don't require a gravity well to act against. Vehicles don't have thruster plates so therefore can't maneuver away from a gravity well as they have nothing to push against. That would make the Maneuver Drive a more advanced version of the same concept and the big difference being deep space maneuvering. Depending on how much of a gravity force you need to operate contra-gravity.

Originally posted by Big Tim:
And this makes Maneuver Drives different than the gravitic engines on vehicles how?

These explanations tend to tell me that you guys are playing them as the same, yes?

 

[clair_rand]

I've always assumed you have thrust axis only drives normally, doing anything else is less efficient. Typically the drive plates heat up a hell of a lot more.

Thus you *can* hover, but not for long, enough for a landing but the ship will 'air stilt' to loose speed in the final stages of the decent. Winged craft naturally have less of a problem with this cept the actual VTOL landing.

Thus a ship puts a pulse in the main drives to get off the ground, and angles upwards pretty fast to bring the thrust in line and reduce the overheat problem.

Ships with higher thrust have larger plates and can hover for longer, partly because of increased power and partly because of increased heat sinks

 

[flykiller]

I've always assumed you have thrust axis only drives normally, doing anything else is less efficient ... Ships with higher thrust have larger plates and can hover for longer, partly because of increased power

'xactly what I do.

 

[aramis]

MT had materials (SSOM, by DGP) stating that drives could produce:
10% rated reverse(170-180° from thrust line)
50% rated at 90° from thrust line
100% rated between 0 and 10° on thrust line.

Also, it said that the drive could be run at up to 300% rating for short periods; so you could, for a short bit, get 150% rated thrust off-axis, for "Star Wars" type TO & Landings.

Using this, you need to figure most ships will come in with A/G on, and unless AF designs, will come in engines down, then rotate over the field to landing gear down (and then A/G off) for touchdown.

 

[TheEngineer]

Yep, SOM provides a very usable and cinematic thruster drive description

What I regard as interesting, is that e.g. the cruising speed calculation for thruster drives in MT does not rely on ships mass or local gravity at all.
Its like that thruster drives "cut" the complete ship out of the influence of the natural gravity, enabling it to use full manuever thrust as thrust.

So, what may happen to an object, that suddenly is cut off local gravity ?
Well, it may start drifting away on your last gravity inluenced vector.
At least, that fits to the TU feature (ok, it contradicts CT/Mayday), that even humble 1g merchants are able to land on >1g world or are capable to refuel at gasgiants.

Actually I like the combination of those two interpretations.

Regards,

Mert

 

[Captain Zoom]

Originally posted by Aramis:
MT had materials (SSOM, by DGP) stating that drives could produce:
10% rated reverse(170-180° from thrust line)
50% rated at 90° from thrust line
100% rated between 0 and 10° on thrust line.

Also, it said that the drive could be run at up to 300% rating for short periods; so you could, for a short bit, get 150% rated thrust off-axis, for "Star Wars" type TO & Landings.

Using this, you need to figure most ships will come in with A/G on, and unless AF designs, will come in engines down, then rotate over the field to landing gear down (and then A/G off) for touchdown.

No offense (cause you've got a better memory than me), but just so we get the right numbers I pulled out my copy of SSOM (one of my favorite books):

10% rated reverse(170-180° from thrust line)
25% rated at 90° from thrust line
100% rated between 0 and 10° on thrust line.

40% overdrive for several days at a time (minimal supervision by engineer)
400% for brief periods under 5 minutes (utmost care by engineer)

This makes high performance craft like SDBs even scarier, since a 6G SDB could put on 8.4Gs of thrust for several days (40% overdrive) to chase down a 1 or 2 G civilian craft, or even a 4G corsair, each of which could only boost to 1.4 G, 2.8 G or 5.6 G for several days. If you've got a hot engineer, I guess an SDB could even make a 400%/24G emergency dodge. Presumably, your inertial compensators are capable of handling 24Gs, or the salvage crew better bring along some sponges to recover the SDB crew.

SSOM also explains that thruster plates are not efficient for vessels under 20 tons. Instead, regular anti-grav tech is better below 20 tons.

Nose up landings/take-offs are explained by saying that passengers/crew keep their "horizontal" orientation using the internal gravity field (thus the floor stays the floor).

I've never gotten the sense from SSOM that spacecraft thrusters cut off gravity like regular anti-grav tech, and have treated them as thrust only systems in the games I've run. The practical scenario-busting problem I've found is if you allow starship thrusters to be used as if they were anti-grav units, then you get players who decide to simply float the starship around like a portable gun platform and use the turret weapons on low tech opponents. At high tech levels, even civilian starship armor is difficult for low tech guys to punch through, and basic turret weapons (e.g. a beam laser) on a starship will shred low tech planes, zeppelins, and even battleships. By treating thrusters as providing thrust, players have to actually fly the starship around and make rolls to stay in the air, as opposed to using minimal skill to simply float around on anti-grav. Also, if the thrusters are anti-grav units, then you wouldn't need to land nose up or use wings to glide in, just float in and apply minimal thrust to push the ship against the ground.

The MT Starship Operator's Manual is awesome. If you can find a copy, I highly recommend getting it. All of the above and more is in the Maneuver Drive section. There are sections on Flight Controls, Jump Drive, Power Plant/Fuel, Sensors/Comm/Transponders, Main Computer/Security, Hull/Environment, Cargo/Passengers, Weapons/Screens, and Crew Duties

 

[aramis]

Oh, ick... yeah, I can't get to my copy.

So that's 100% abeam... and 400% TO... which means even a 1G ship can T/O and Land on even size D worlds (which dont' occur in canon...) on their tails.

 

[LordVince]

Old Fart butting in here....

As has been said by some of the Original Insiders, the early days of CT were influenced by the writings of H. Beam Piper.

In his writings, he presented the concept of ContraGravity flight systems. In one book ("Junkyard Planet" later re-named "The Cosmic Computer") Piper went into the fact that the CG system used what he called the "Lift and Drive" method: there was only 1 "generator", but it's output whas shunted into the two different uses. I always got the impression that it was a 50/50 ratio of Lift over Drive power. At most a 40/60 ratio. CG vehicles COULD and DID hover, but he always implied (IMHO) that without "thrust" the CG hovering vehicles were slow to react/maneuver.

This is important because, as Piper described them, "regular" CG vehicles -- what Traveller would call "Grav Vehicles" -- "lost" power, the higher they climbed. They had decent performance in the areana of "air vehicles", but quickly lost power as you approached "orbital" altitudes.

This was a plot point in the afforementioned novel. Someone had stolen/hijacked a large CG transport (think of it as a cross between an airliner, a passenger train, and a small cruiseship), and needed to spends months "realigning" the Lift and Drive modules into a purely "Drive" mode -- which would THEN make the vehicle an interplanetary one.

Also, in many Piper novels, he wrote that large vessels -- 100+ dtones -- would often just use their CG Drives to cancel out, like, 98% of the planet's gravity-pull, and then let smaller "tugs" pull it down to a landing field.

I've always felt/played Traveller "Maneuver Drives" the same way. The M-Drives produce a gravitic "thrust effect". In Space, the entirety of this effect is directed in a single vector. When "landing", or maneuvering in the gravity effect of a planet/whatever, then some of this "effect" is "vectored" as both "Lift" and "Drive" and also a little is siphoned off for "Attitude Maneuvering".

Traveller has always made an issue of the "Thruster Plates" placed like rocket exhausts -- which works, for me, as they are the primary focal devices for "full forward thrust". I ALSO go the one step further and say that there are a series of smaller "Ventral Thruster Plates" running along the "bottom" of a ship -- I call these the "Landing Thrusters" -- and of course there are many small clusters of "Thruster Plate Verniers" located at strategic points around the ship for changing directional attitude.

Thus, IMTU, a CG Thruster Plate equipped ship can hover using just it's "Landing Thrusters". It could also rise, vertically, on these thrusters, but they start to "strain" after passing @50,000 feet. AND, using just the "Landing Thrusters" and the "maneuvering Verniers" it CAN fly -- with the flight characteristics of a Blimp. Slow and unweildy. It takes using the "Drives" to give any kind of decent "agility". And, of course, it would take the kind of power that the "drives" generate to challenge the effects of heavy weather.

So, using just the "Lift" aspects of the M-Drive, your ship acts like a Balloon.
Using the "Lift-and-Drive" mode, your ship acts like an Aircraft.
And, using the full "Drive" mode, your ship acts like a Rocket.

 

[Fritz_Brown]

I have always thought that anti-grav made for a very poor manuevering thrust source. If we use Einsteinian assumptions about gravity, then there is some everywhere, but most of it is drowned out by gravity wells like planets. This basically gives you one direction to push. And it gets worse, the closer to a planet surface you get. So, G-carriers and air rafts are pigs unless they have some kind of thrusters.

Also, I would think that you would need some aerodynamics to land in atmosphere, because of the reentry. You can't really enter an atmosphere at 0 relative velocity. So, a non-aerodynamic craft (and I count external antennas, etc. in this) would not be smart to land at a downport, unless you really enjoy riding in like a meteor.

 

[Fritz_Brown]

BTW,
Where can I find discussions of jump drive, how it works, etc. in the CT (or other) books? There does not appear to be ANY discussion of the science in the 8 original books, or the supplements (1-13).

 

[Malenfant]

There's a little bit of info in TNE's "Fire Fusion and Steel", but not much beyond "ship opens hole in space, falls down it for a week, and pops out somewhere else"

MWM himself wrote an article on Jump Space in the online JTAS - the article can be found here but you have to be a JTAS susbcriber to read it.

There might be entries in the CT library data supplements too, or the Imperial Encyclopaedia - have you checked those?

And the DGP Starship Operators Manual probably has something relevant in it too...