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- Thread starter Ishtar
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At (Traveller) TL10, the standard maneuver drive is the HEPlaR - High-Energy Plasma Recombination

a variation of a fusion rocket.

At TL12, the standard becomes the thrust plate. It is more than just a Contra-Grav, the Thrust Plate pushes off of existing gravity fields to propel the ship, thus they decrease in effeciency as they travel away from a gravity well..

-MADDog

While CT never specifically states, it is pretty obvious that they also used reactionless thrusters, though they were volume based, not mass based. T20 uses the same unidentified reactionless thrusters as CT.

In MT there were both reactionless thrusters and gravitic drives. The thrusters were bigger and more expensive, but didn't require a gravity well to operate effectively.

In TNE they introduced heplar (I forget the weird capitalization). This is a pure fusion reactor manuever drive. The also retained the reactionless thruster, though there was a TL floor for its introduction.

So, pick the system you are using, and find your answer.

One of the reasons I asked was that I was wondering whether or not there would be some sort of waste product from the drives- plasma or biohazardous liquid of some sort. It seems pretty clear that LHyd is the sole fuel used on most starships with a fusion power plant (by all means, correct me if I am wrong).

One more question: H2 is highly explosive. How volatile and flammable is it in liquid form (LHyd)?

--Courtney

Only volatile and flammable when mixed with Oxygen.Originally posted by Empress Nicholle:

One more question: H2 is highly explosive. How volatile and flammable is it in liquid form (LHyd)?

--Courtney

-MADDog

There's some recent evidence that hydrogen itself is a potential pollutant; it tends to interact in the upper atmosphere, breaking down the ozone layer. The degree of danger isn't yet clear.Originally posted by MADDog:

Not many polutants from hydrogen

CT started with fusion torches and chemical thrusters (the latter only on small craft, and only in Mayday, which gave very limited fuel endurances for fighters (4G acceleration for 3 turns ISTR)). Later it was grav plates, back to rockets for TNE and then back to grav plates later.Originally posted by Empress Nicholle:

I have a question about Starship maneuver drives in Traveller. Are they grav-based or do they use something like chemical thrusters to move in space, or both, or neither?

Also, what is the value of G? Is it an earth g (9.8 m/s if I'm not mistaken)?

--Courtney

G is 9.8 m/s2 (the squared is important). That's the acceleration due to gravity on Earth. Usually rounded to 10m/s2 for most practical purposes.

So, accelerating at 1G, after 1 second you're moving 10m/s, after 2, 20m/s, after 3, 30m/s etc.

There's no balancing force of friction like there is in an atmosphere, so with unlimited thrust you can continue accelerating for a long time, getting ever and ever closer to the speed of light.

Bryn

Or not. Technically, your car works on a reactionless principle, I've never yet had to empty the CO out of my fuel tank to refill. It's quite possible (although it would be stupid to waste 'free' thrust IMHO) to just dump the helium out your 'exhaust pipe'Originally posted by Tom Kalbfus:

Granted, as someone pointed out in another post somewhere, one could posit the value of 1-g as 10 meters/second/second, rather than 9.8, but liftoff would still be *awfully* slow.

Is it just me, or did someone really foul up on this one? Shouldn't any fully streamlined ship intended to land on a variety of worlds in a variety of systems have 2-g maneuver drives?

I believe 2-g should suffice - I believe I have read in an astronomy text or two that the Earth is about as large as terrestrial planets can get. If a planet forms with much more mass, it becomes a gas giant.

I believe that in CT/MT there has always been an unwritten assumption that the maneuver drives (whether the generic CT thrusters, or MT contra-grav or thrusters) have always had a contra-grav component suffient to "negate" planetary gravity, and provide the rated acceleration on top of that. For game playability, CT/MT never addressed the issue of varying planetary gravities. Remember, SDB are supposed to lurk (hovering) in GG atmospheres on their CG/thrustersOriginally posted by Isaac_1963:

Granted, as someone pointed out in another post somewhere, one could posit the value of 1-g as 10 meters/second/second, rather than 9.8, but liftoff would still be *awfully* slow.

Is it just me, or did someone really foul up on this one? Shouldn't any fully streamlined ship intended to land on a variety of worlds in a variety of systems have 2-g maneuver drives?

I believe 2-g should suffice - I believe I have read in an astronomy text or two that the Earth is about as large as terrestrial planets can get. If a planet forms with much more mass, it becomes a gas giant.

I just took a look at the good old Megatraveller Starship Operators Manual....:

...plates may be overdriven for up to 40%...

...overdriving the plates by up to 400 % (as in the case of a 1g ship trying to do a lateral hover at takeoff or landing) takes the upmost care, and can only be done for brief periods of time (under 5 minutes)....

If there is interest I could provide an extract of

the paragraph...

Best regards,

Mert

How long does it take a 1-g drive, 2-g drive, and etcetera to accelerate to 10 percent speed of light? Does a 6-g drive accelerate 6 times faster, or is each increase an exponential increase?

The equation is:

Velocity = (Acceleration)x(time)

so, Time (to reach a certain velocity) = (that velocity)/(acceleration)

1G = 9.8 meters/second squared, let's round that to 10 meters/second squared just to make the math easier. 2 G is twice that or 20 meters/second squared, and 6 G is then 120 meters/second squared.

The speed of light (in a vacuum) is 300,000,000 meters/second (again, that's a slight rounding).

10% of this is 30,000,000 meters/second.

So....

Time (at 1 G)=30,000,000 meters per second/10 meters per second squared = 3,000,000 seconds = 833.3 hours at 1 G to get to 10% light speed

Time (at 2 G)=30,000,000 m/s divided by 20 m/sec squared = 1,500,000 seconds = 416.7 hours at 2 G to get to 10% light speed.

Time (at 6 G)=30,000,000m/s divided by 120 m/second squared = 250,000 seconds = 69.4 hours at 6 G to reach 10% light speed.

So the time to reach a certain speed (at constant acceleration) is inversely proportional to the acceleration. In plain English that means that it takes 1/6 the time at 6G to reach a certain velocity as it would take at 1G.

Given that the time it takes to travel to a far gas giant is only 166.7 hours even at 1G (numbers from LBB2) it's not very likely that even a 6G ship would ever approach 10% of lightspeed in a Traveller game.

Uh, not to be completely annoying, but shouldn't 6G be 60 m/s/s instead of 120 m/s/s?Originally posted by The Oz:

1G = 9.8 meters/second squared, let's round that to 10 meters/second squared just to make the math easier. 2 G is twice that or 20 meters/second squared, and 6 G is then 120 meters/second squared.

...

Time (at 6 G)=30,000,000m/s divided by 120 m/second squared = 250,000 seconds = 69.4 hours at 6 G to reach 10% light speed.

That would make the result for 6G 138.8 instead of 69.4. (Which fits the 1/6 of 833.3 you were looking for.)

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