Thruster pack capabilities.

[captainjack23]

From v2.0:

TL12: The long-range thruster pack gives 2g acceleration for up to 48 hours, using standard starship fuel. Cr. 14,000.

Whooooo -Hoooooo ! This is a long way. 2g x 48 hours ~= 100 Million km; out to mars and the asteroid belt, I believe, and 2/3 of the way inward to the sun… plus, you will have a MASSIVE velocity at the end of this, leading to all kinds of issues as regards collisions, intentional or otherwise... Plus, if this does that, then what do missles use ?.

I'd suggest handwaving that this is the same truster that a missle would use, with more compensation and thus less acceleration for a given power pack; and with a similar duration : assumption is that a standard missle can achieve 5-6G for 3-6 turns with no compensation.

 

[AKAramis]

From v2.0:

TL12: The long-range thruster pack gives 2g acceleration for up to 48 hours, using standard starship fuel. Cr. 14,000.

Whooooo -Hoooooo ! This is a long way. 2g x 48 hours ~= 100 Million km; out to mars and the asteroid belt, I believe, and 2/3 of the way inward to the sun… plus, you will have a MASSIVE velocity at the end of this, leading to all kinds of issues as regards collisions, intentional or otherwise... Plus, if this does that, then what do missles use ?.

I'd suggest handwaving that this is the same truster that a missle would use, with more compensation and thus less acceleration for a given power pack; and with a similar duration : assumption is that a standard missle can achieve 5-6G for 3-6 turns with no compensation.

Using "Traveller Standard" 10m/s/s G's (rather than Real World 9.8m/s/s),

(48*3600)^2 * 10/2 = 149,299,200,000m = 149.3 Million KM; mars is mean orbital distance of 227.94 Million KM... (Earth is 149.6 Million KM Mean Orbital distance), for a closest approach of 78.34 Million KM...

So yes, close enough to hit mars about 4 months of the year....

 

[Deniable]

So yes, close enough to hit mars about 4 months of the year.

If he's not doing turnover in the middle, hit is an accurate description. A perfect litho-braking maneuver.

 

[AKAramis]

So yes, close enough to hit mars about 4 months of the year.

If he's not doing turnover in the middle, hit is an accurate description. A perfect litho-braking maneuver.

If he hits a pebble en route, he's dead anyway.

 

[Rikki Tikki Traveller]

Thrusters are going to have a maximum velocity based on the nozzle exit velocity. If the thruster pack has a maximum nozzle exit velocity of 20 kps, then that will be the maximum theoretical velocity that the person using it could obtain. That velocity will NOT get you to Mars any time soon. It WOULD give you 2g acceleration, but not for 48 continuous hours in the same direction.

The idea of the thruster pack is that it gives you acceleration for a short period of time, not continuous thrust for days.

 

[far-trader]

...The idea of the thruster pack is that it gives you acceleration for a short period of time, not continuous thrust for days.

(oops, my mistake, RTT confused me again, tricked me into thinking this was from the actual game designers the points are still valid, just not official )

Precisely, well summarized, and thank you for the confidence restoring clarification.

It would be good to have that in the item description then or you know players and refs will be doing it wrong.

Or better yet, drop the whole 2g for 48 hours endurance (a ridiculous amount anyway in my opinion) to something more reasonable and closer to the maximum thrust capability. Maybe 0.2g for an hour or two. More than enough time for a simple high orbit bail and insertion, or an EVA repair task, or popping over to a drifting ship after matching vectors. These things aren't meant to be "Backpack to Mars" should be emphasized.

 

[AKAramis]

Thrusters are going to have a maximum velocity based on the nozzle exit velocity. If the thruster pack has a maximum nozzle exit velocity of 20 kps, then that will be the maximum theoretical velocity that the person using it could obtain. That velocity will NOT get you to Mars any time soon. It WOULD give you 2g acceleration, but not for 48 continuous hours in the same direction.

The idea of the thruster pack is that it gives you acceleration for a short period of time, not continuous thrust for days.

You're presuming a non-gravitic/T-Plate pack.

 

[far-trader]

You're presuming a non-gravitic/T-Plate pack.

True, but I thought T/plates had a minimum size much larger than a backpack and simple gravitics only worked in a strong gravity well.

Even so it still seems ridiculously small for the performance. If scaled up to small craft/starship size drives, ignoring economies of scale, wouldn't that far outperform the usual thrusters and powerplants?

 

[Rikki Tikki Traveller]

My assumption is that Gravitics are not used. The description of the item, and it's introductory TL both suggest that it is NOT gravitic based.

I envisioned it as something like what we have now (experimentally) for the Space Station. A backback with control nozzles that fire small jets of gas to let someone move around in space. Better units would be able to match orbits (within certain limits) and allow individuals to transfer between ships that are a couple of km apart.

Gravitic packs could be used for reentry, but would not work outside of a planetary gravity well.

 

[captainjack23]

My assumption is that Gravitics are not used. The description of the item, and it's introductory TL both suggest that it is NOT gravitic based.

My assumption is that it's a typo.

I envisioned it as something like what we have now (experimentally) for the Space Station. A backback with control nozzles that fire small jets of gas to let someone move around in space. Better units would be able to match orbits (within certain limits) and allow individuals to transfer between ships that are a couple of km apart.

Makes sense. I understand about nozzle velocity limitations & etc. But, 48 hours of reaction mass for even .2g would be fairly bulky..numbers anyone ?

However, we don't really need to work on the rationalization/visualization here if the numbers suggest a mistake.:wink:

Gravitic packs could be used for reentry, but would not work outside of a planetary gravity well.

Except where they do. Thruster , and reaction performance in Traveller are a BIG can o' worms issue. ?

Plus, even if that is the case, the sun has a gravity field, and a big one, too. As does the Galaxy. Enough to work a gravitic drive ? Why, yes. Certainly enough. Existing real world reactionless gravitic thruster examples do not contradict this assertion.....

8)

Cap

 

[AKAramis]

My assumption is that Gravitics are not used. The description of the item, and it's introductory TL both suggest that it is NOT gravitic based.

I envisioned it as something like what we have now (experimentally) for the Space Station. A backback with control nozzles that fire small jets of gas to let someone move around in space. Better units would be able to match orbits (within certain limits) and allow individuals to transfer between ships that are a couple of km apart.

Gravitic packs could be used for reentry, but would not work outside of a planetary gravity well.

Considering the wording is lifted straight from MT, which also fails to define it, other than standard starship fuel, a 1/2 ton of thrust pack would be 15L of gravitics, 4L of fusion plant and not nearly so much fuel as to fill out 65L...

Oh, and the physics of motion don't restrict your thrust to the speed of your exhaust when in vaccum; if you go faster than that, it's still being slowed by the same amount over all, and you continue to accellerate so long as you have fuel.

Now, given that 40L of fuel, that fuel is needing to be given roughly 300Kg/m/s/s accelleration to assure said performance... if we assume a liter an hour for fuel, that's 70g/hour, so to get 300000g/m/s we need that 0.00001944 g/sec fuel, so it needs to hit 15,432,098,765m/s on the fuel. 300,000,000,000m/s is roughly C, so it's roughly 1.9% of C for the exhaust. In short, if it's reaction based, it's a hydrogen ion thruster, and is also an alpha radiation canon.

(the same can no be said for impellers in atmosphere.)

 

[captainjack23]

You're presuming a non-gravitic/T-Plate pack.

True, but I thought T/plates had a minimum size much larger than a backpack and simple gravitics only worked in a strong gravity well.

See: grav belt.

Even so it still seems ridiculously small for the performance. If scaled up to small craft/starship size drives, ignoring economies of scale, wouldn't that far outperform the usual thrusters and powerplants?

Yes, my point exactly.
Still: missiles = 6G x 2 hours. 1mx 100cm, 70kg.

At grav tech levels, I could see 2g for 4 hours for a man size payload....I guess....but 48 hours ?

Otherwise, load up with thruster packs, boys ! Way longer range than missiles, bigger payload (100kg warhead, min), and totally legal. (well, except for the bomb part). Plus, at max V, all you need is a bag of cement as a warhead.

Yeah, its a typo.

Cap

 

[Exwrestler]

Step 1. Get yourself a boatload of savages from a low tech world.

Step 2. Train them in the basics of Vacc Suit and Flyer-Grav.

Step 3. DO NOT train them in the basics of Science-Physics.

Step 4. Put them in grav equipped vacc suits.

Step 5. Arm them with spears (or bags of cement).

Step 6. Order them to charge and board the vessels of your enemy (making sure they are a long way off).

Step 7. Laugh your way to Galactic Domination!!

 

[pasuuli]

Or better yet, drop the whole 2g for 48 hours endurance (a ridiculous amount anyway in my opinion) to something more reasonable and closer to the maximum thrust capability. Maybe 0.2g for an hour or two. More than enough time for a simple high orbit bail and insertion, or an EVA repair task, or popping over to a drifting ship after matching vectors. These things aren't meant to be "Backpack to Mars" should be emphasized.

This seems reasonable to me. Imagine how uncomfortable it would be to take such a long trip in a rocket-powered vac suit anyhow!

Drug me, please...

 

[Malakor]

Step 1. Get yourself a boatload of savages from a low tech world.

Step 2. Train them in the basics of Vacc Suit and Flyer-Grav.

Step 3. DO NOT train them in the basics of Science-Physics.

Step 4. Put them in grav equipped vacc suits.

Step 5. Arm them with spears (or bags of cement).

Step 6. Order them to charge and board the vessels of your enemy (making sure they are a long way off).

Step 7. Laugh your way to Galactic Domination!!

Uhm, you realize that I read this board and you're giving me evil ideas? :lol: :lol: