T5 Question about Maneuver Drives

[Supplement Four]

I'm no where near the chapter on Maneuver Drives, so maybe the answer is there. But, I just noticed in the Range Band chapter (page 41) that maneuver drives are inefficient beyond 1000 diameter limit (they are reduced to 1% of function).

Is that 1000 D of a world or the system's star? (I'm guessing star.)

And...since the four major drives in T5 are the M-Drive, the J-Drive, the G-Drive (gravitic), and Lifters, how is it that a ship maneuvers in deep space?

Or does it?

If a mis-jump happens placing the vessel at 2000 diameters of the closest star, is the crew of the ship out of luck? They can't use the M-Drive to head to the system?

 

[rancke]

0.01G acceleration will get you there in time. And not a hundred times slower either. (Specific examples are beyond my meager knowledge on the subject).


Hans

 

[Daddicus]

The 1000 D is from any body of mass larger than your ship. In the Solar System, our sun has a diameter slightly less than 1,400,000 km. Saturn's orbit is slightly more than 1,400,000,000 km. Saturn's orbit is just past 1000 solar diameters.

So, a ship flying around Saturn wouldn't be in the sun's 1000 D range, but it would be inside Saturn's, so the drives would still work.

However, there are many places between Saturn and the outside edge of the Solar System where a ship would not have any body within 1000 D of that body's center.

Now, to the question: A ship that misjumps into an area with no body in range has a problem. But, it's not absolute. Most of the gravity-based drives don't completely lose power beyond their range, but rather lose efficiency (about 99%). So, they're going to be slow, but they can still move.

Plus, there's all sorts of junk in space. For instance, there are a few larger bodies of mass past Neptune that could supply a gravity well for these drives to tap.

Rancke correctly points out that 0.01G acceleration is not speed, but acceleration. So, even at that pathetic rate, the ship would still be increasing speed at 0.1 m/s every second. After an hour, it would be going 360 m/s as long as it kept accelerating in the same direction. In a day, ~8000 m/s. One would hope to run by some piece of space junk in not too many days.

 

[Supplement Four]

The 1000 D is from any body of mass larger than your ship. In the Solar System, our sun has a diameter slightly less than 1,400,000 km. Saturn's orbit is slightly more than 1,400,000,000 km. Saturn's orbit is just past 1000 solar diameters.

So, a ship flying around Saturn wouldn't be in the sun's 1000 D range, but it would be inside Saturn's, so the drives would still work.

According to page 41, then, this can lead to a very interesting situation.

If you're in a system with a class K star, then the 1000 D limit of that star is Space Range Band 12.

How would a ship travel to the Oort Cloud in orbit 19 (Space Range Band 20)?

As I'm reading this, it ain't really possible with normal ships. I'm guessing it would take a specially designed vehicle for the trip? And, you wouldn't have any space stations in the Oort Cloud because they couldn't get any supplies.

 

[aramis]

I'm no where near the chapter on Maneuver Drives, so maybe the answer is there. But, I just noticed in the Range Band chapter (page 41) that maneuver drives are inefficient beyond 1000 diameter limit (they are reduced to 1% of function).

Is that 1000 D of a world or the system's star? (I'm guessing star.)

Both & Either. Tho' for most worlds, the star will be further than the planet.

As long as you're within 1000 diameters of either, you're at full thrust.

 

[Supplement Four]

As long as you're within 1000 diameters of either, you're at full thrust.

Point being: Yes, the star's 1000 D limit covers most of the system, but not all of it!

In the outer reaches of the system, there must be danger zones where your go-go machine don't go-go no more.

 

[robject]

According to page 41, then, this can lead to a very interesting situation.

If you're in a system with a class K star, then the 1000 D limit of that star is Space Range Band 12.

How would a ship travel to the Oort Cloud in orbit 19 (Space Range Band 20)?

As I'm reading this, it ain't really possible with normal ships. I'm guessing it would take a specially designed vehicle for the trip? And, you wouldn't have any space stations in the Oort Cloud because they couldn't get any supplies.

Could be an S.O.L. situation. Or an opportunity for novel solutions. Plus perhaps some insystem jump action?

 

[Supplement Four]

Could be an S.O.L. situation. Or an opportunity for novel solutions. Plus perhaps some insystem jump action?

Mayday, Mayday, Mayday....this is the Beowulf calling....We've left Pluto but drifted into a no-G pocket...

Alert the micro-J boats!

 

[aramis]

Mayday, Mayday, Mayday....this is the Beowulf calling....We've left Pluto but drifted into a no-G pocket...

Alert the micro-J boats!

Yep.

Actually, since it drops off, not completely off, if one has a M-Drive but not J-Drive, one CAN do a continuous burn course between systems. It's better than coasting. 0.06G is better than the fastest man-made probe had (it was under 0.001G). But a few weeks at that steady thrust sure adds up.

 

[rancke]

Actually, since it drops off, not completely off, if one has a M-Drive but not J-Drive, one CAN do a continuous burn course between systems. It's better than coasting. 0.06G is better than the fastest man-made probe had (it was under 0.001G). But a few weeks at that steady thrust sure adds up.

Only trouble there is if you actually use the ridiculous power plant fuel consumption figures. In such a case a few weeks added to a journey can be a death sentence.


Hans

 

[Supplement Four]

Only trouble there is if you actually use the ridiculous power plant fuel consumption figures. In such a case a few weeks added to a journey can be a death sentence.

I was thinking about life support: food, air, water.

 

[whulorigan]

And...since the four major drives in T5 are the M-Drive, the J-Drive, the G-Drive (gravitic), and Lifters, how is it that a ship maneuvers in deep space?

Or does it?

If a mis-jump happens placing the vessel at 2000 diameters of the closest star, is the crew of the ship out of luck? They can't use the M-Drive to head to the system?

According to page 41, then, this can lead to a very interesting situation.

If you're in a system with a class K star, then the 1000 D limit of that star is Space Range Band 12.

How would a ship travel to the Oort Cloud in orbit 19 (Space Range Band 20)?

As I'm reading this, it ain't really possible with normal ships. I'm guessing it would take a specially designed vehicle for the trip? And, you wouldn't have any space stations in the Oort Cloud because they couldn't get any supplies.

Could be an S.O.L. situation. Or an opportunity for novel solutions.

Only trouble there is if you actually use the ridiculous power plant fuel consumption figures. In such a case a few weeks added to a journey can be a death sentence.

Well, according to the top of the 1st page in the section "How Manuever Works", there are other drives systems mentioned that are simply not detailed in the T5 Rulebook (presumably they will be covered in a future BCS supplement ?). One of those is HEPlaR (the TNE/T4 Plasma-Thermal Rocket), and also "Thrusters" (MT's Strong-Nuclear Force based M-Drive, perhaps ?).

So maneuvering in the outer system could be accomplished by ships designed in T5 with certain other drives that are yet to have their stats published.

Now, to reopen an old can of worms from another thread :
Maybe in some special cases (e.g. Scouts), those "rocket-nozzles" on the back of ships could be a basic reserve HEPlaR rocket-thruster with a limited fuel supply for emergency use (depending on how much space a HEPlaR "R-Drive" would take up?).

 

[Magnus von Thornwood]

Or for the desperate, who's for dinner?

I was thinking about life support: food, air, water.

See that is why I always have at least, the very least 1 ton of long term life support, for those long times at sublight.

 

[pendragonman]

Here's another thought.

As far as I can tell you all are talking about a ship/boat being outside the limit starting from a zero vector. I.E. dead stop.

You had to start from somewhere. Your ship didn't just occur out there in dead stop space. You were moving from somewhere to somewhere else.

Therefore you were accumulating velocity along your thrust line for that entire time. Coast. Use the .01 (or whatever it is) efficiency as course corrections, but your accumulated velocity won't degrade much. After all, to degrade means interacting with a close gravity well, and therefore your manu is back to efficient levels.

Now, supposing on the other hand you misjumped into such a space outside every reasonable gravity source, well misjumping is dangerous stuff.

 

[whulorigan]

[FONT=arial,helvetica]

Or for the desperate, who's for dinner?
[/FONT]

What! Long Pork AGAIN . . . o:

 

[Frewfrux]

Here's another thought.

As far as I can tell you all are talking about a ship/boat being outside the limit starting from a zero vector. I.E. dead stop.

You had to start from somewhere. Your ship didn't just occur out there in dead stop space. You were moving from somewhere to somewhere else.

After jumping, do you re-enter N-space with your previous vector?

 

[Magnus von Thornwood]

Hey!

What! Long Pork AGAIN . . . o:

Look it is still three weeks in till we hit something to "push" against, so you want I should eat your share? :devil:

 

[whulorigan]

After jumping, do you re-enter N-space with your previous vector?

That has been the traditional interpretation in Traveller according to various rulesets (although in MgT it leaves the question open).

 

[robject]

Now, to reopen an old can of worms from another thread :
Maybe in some special cases (e.g. Scouts), those "rocket-nozzles" on the back of ships could be a basic reserve HEPlaR rocket-thruster with a limited fuel supply for emergency use (depending on how much space a HEPlaR "R-Drive" would take up?).

Now that's a very clever suggestion.

 

[esampson]

While 1% effectiveness seems like the ship is absolutely crippled, in reality it is far from it. Yes, modern rocket engines that push ships up to the ISS have multiple G's of acceleration, but that is because they do their job very, very quickly. I came to a much better understanding of this when I was dealing with space ships in Eclipse Phase which are pretty hard sci-fi ships but which are typically ill-defined (often you are told the acceleration capability of the ship but no clue as to how long it is able to maintain that acceleration, and they are not Traveller style ships where they are capable of maintaining the acceleration for weeks on end.)

Because of the formulas involved 1% thrust means that the trip takes 10 times longer. Whenever you increase thrust (assuming you are capable of maintaining the burn throughout the trip) the change in duration is the square root of the change in thrust (e.g. A ship under 4G thrust will make the trip in half the time as a ship under 1G).

Increasing the duration of the trip by an order of magnitude might seem like a lot, but given a lot of the time frames involved it actually isn't. Certainly it would be a problem for a ship not designed for those time frames, but it is not too difficult to design a ship with enough fuel and life support for several months.

Additionally, you have to remember that not only as other people have pointed out are you able to use the drives at full effect for part of the trip but in the case of a ship that misjumps you still have a working jump drive. Assuming you are 1500D out and on a vector that isn't going to take you towards the mass that made you precipitate any time soon (and assuming that mass will allow you to refuel) you could actually plot a new jump course so that you drop out of J-Space 100D away from the object and on a good vector. Since you are executing what is essentially a Jump-0 the fuel used by the jump would be minimal, though you would spend an entire week in J-Space. Moral of the story; always design your ships with at least a few extra weeks of life support and power plant operations.