Escape Velocity Problem Returns in T5!

[Supplement Four]

The old debate from CT returns in T5: Can a ship with an M-Drive that produces 1G of thrust make escape velocity from a Size 8+ world (where surface gravity is 1+Gs)?

Some CT Refs just handwaved it and said, "Yes". Others stipulated that M-Drives producing 1G were limited to orbit and Highports around Size 8+ worlds.

I've always liked this debate, and I side with 1G limited vessels. I like the obstacle it provides for players in the game, and I like the character that it gives to some systems.

I remember that there was an old White Dwarf article that addressed this issue (there's a thread about it in the CT forum somewhere...do a search for "Escape Velocity") with the solution being detachable booster rockets that could be purchased for 1G ships and some local starports. These rockets produced the extra thrust to allow 1G ships to reach escape velocity, and after the ship breaks oribt, the rockets were discarded (probably as space trash)

When MT came along, DGP's the SOM addressed this by stating that M-Drives have an "overdrive" function where, for short periods of time, the M-Drive can produce a little more thrust, defeating this problem on 1G vessels.

Well, now, I see that T5 has returned with the issue (as I said, I think it's a cool tool for the Ref--players will want to upgrade their M-Drive, a great "push" for adventures).

T5, page 364, clearly states: If the Drive cannot produce aceleration equal to the local gravity, the ship impacts the surface with Speed=13.

I'll note that the "equal to local gravity" bit makes 1G vessels ok on Size 8 worlds--it's Size 9+ that will have the issue.

 

[Supplement Four]

I also see a neat, quick rule that I like. Page 364:

To Orbit in Minutes (Fast*) = World Size + Atmosphere

To Orbit in Mintues (Slow) = World Size

To Orbit in Hours (Safe) = 5 x World Size

*The ship may take damage due to friction, depending on the Atmosphere type.

 

[rancke]

T5, page 364, clearly states: If the Drive cannot produce aceleration equal to the local gravity, the ship impacts the surface with Speed=13.

I'll note that the "equal to local gravity" bit makes 1G vessels ok on Size 8 worlds--it's Size 9+ that will have the issue.

As far as I am concerned, the issue will be decided by whether or not T5 adventure writers address it or not. If they blithely ignore the problem and assume that the PCs' ship can land on the size 10 world the adventure is placed on regardless of its G rating, I'll conclude that the rule you just quoted is wrong.

Or a setting writeup could do it too. "Only ships with 2G maneuver drives ever visit Bigworld, because ships with only 1G maneuver drives can't land there. There has been talk of building an upport, but so far the finances have not been there." [Adventure on Bigworld, p. 17]


Hans

 

[esampson]

While the rule you quoted does exist it also doesn't make any actual sense, most of the time. There is a specific piece of ship equipment (lifters) which basically allow the ship to float. They don't provide significant amounts of thrust themselves but when coupled with even low thrust drives you are effectively able to take off from any planet, provided the gravity isn't so high it overwhelms the lifters (but in a case like that I suspect the character would be killed).

Additionally ships with either wings or lifting bodies would be able to escape the planet without lifters, assuming their thrust is at least reasonably close to the gravity of the planet. They would simply fly until the atmosphere becomes so thin it is unable to lift them. At that point the atmosphere would also be so thin that they would have maximum velocities capable of establishing stable orbits. Once any object is in a stable orbit it is able to escape with even weak acceleration provided it can sustain that acceleration for long periods of time (such as Traveller ships are able to do).

 

[Supplement Four]

As far as I am concerned, the issue will be decided by whether or not T5 adventure writers address it or not. If they blithely ignore the problem and assume that the PCs' ship can land on the size 10 world the adventure is placed on regardless of its G rating, I'll conclude that the rule you just quoted is wrong.

Or a setting writeup could do it too. "Only ships with 2G maneuver drives ever visit Bigworld, because ships with only 1G maneuver drives can't land there. There has been talk of building an upport, but so far the finances have not been there." [Adventure on Bigworld, p. 17]

Why let someone else make the decision? Instead of you as Ref of your own TU?

While the rule you quoted does exist it also doesn't make any actual sense, most of the time. There is a specific piece of ship equipment (lifters) which basically allow the ship to float. They don't provide significant amounts of thrust themselves but when coupled with even low thrust drives you are effectively able to take off from any planet, provided the gravity isn't so high it overwhelms the lifters (but in a case like that I suspect the character would be killed).

Additionally ships with either wings or lifting bodies would be able to escape the planet without lifters, assuming their thrust is at least reasonably close to the gravity of the planet. They would simply fly until the atmosphere becomes so thin it is unable to lift them. At that point the atmosphere would also be so thin that they would have maximum velocities capable of establishing stable orbits. Once any object is in a stable orbit it is able to escape with even weak acceleration provided it can sustain that acceleration for long periods of time (such as Traveller ships are able to do).

Those arguments were put forth in the CT debates, too!

As I said above, though, I like that it's back. I've always enjoyed using it in my games.

 

[aramis]

CG lifters became canonical in TNE, were in T4, and are in T5. With lifters and a 1G drive, the ship can make 0.98G AFTER a local 1G field.

Lifters render the whole discussion moot, unless the ref ignores or disallows them, at which point, one is decidedly no longer in the OTU.

 

[Supplement Four]

Lifters render the whole discussion moot, unless the ref ignores or disallows them, at which point, one is decidedly no longer in the OTU.

Yet Marc did write the rule I quoted above. If it"s moot, then why write the rule.

Maybe it's not so moot.

 

[rancke]

Why let someone else make the decision? Instead of you as Ref of your own TU?

Because it goes without saying that in my own TU I'm the one that makes the decision. Hence I must be talking about the OTU, where I'm definitely not the one that makes the decision. If those who write up the setting conform to a rule, the rule is correct (for the OTU). If those who write up the setting contradict the rule, the rule is wrong (for the OTU).


Hans

 

[Supplement Four]

Because it goes without saying that in my own TU I'm the one that makes the decision. Hence I must be talking about the OTU, where I'm definitely not the one that makes the decision. If those who write up the setting conform to a rule, the rule is correct (for the OTU). If those who write up the setting contradict the rule, the rule is wrong (for the OTU).

Interesting...since it is Marc who wrote the rule in T5.

 

[rancke]

Interesting...since it is Marc who wrote the rule in T5.

He also wrote about jump shadowing yet neither rules nor adventures took any notice of that for many many years.


Hans

 

[Vladika]

He also wrote about jump shadowing yet neither rules nor adventures took any notice of that for many many years.


Hans

Marc has contradicted himself so many times over the years what difference does it make anymore?

 

[rancke]

Marc has contradicted himself so many times over the years what difference does it make anymore?

Sort of what I meant. If he follows up on his own rules and setting, I'll go along for the sake of internal consistency. If he doesn't pay attention to his own rules and setting, why should I bother?


Hans

 

[Supplement Four]

HERE's THE ORIGINAL THREAD, from 7 years ago!

 

[Magnus von Thornwood]

Re: Lifters.

I have always figured that Lifters are rated to the G rating of the M-drive.

Which means that if you have a 1G M-Drive you have 1G Lifters installed, so you are back to square one. Also note that Lifters are slow (Speed 5, Slow, 50 kph) so even if you use them you aren't doing an speed runs to orbit.

And like Supp4 I like the idea of some worlds being to big for some ships to land on, as he said it allows for some character.

 

[aramis]

CG Lifters in TNE and T4 reduce gravity effect by 98%. They provide no actual lift. The M-Drive or other NAFAL drive does the actual pushing.

So, a ship with 0.01G thrust but standard lifters is limited to worlds under 0.5G. A 1G drive is limited to 50G's... making skimming easy.

In TNE, it was a balance for the nasty business of taking away our space-opera-esque M-Drives.

 

[Supplement Four]

And like Supp4 I like the idea of some worlds being to big for some ships to land on, as he said it allows for some character.

It's really only ships with 1G M-Drives that have an issue, and the issue pops up occasionally (when visiting a size 8+ world, or, in the case of T5, a size 9+ world). 1G drives are the most common, but there may be only one size 9+ world in the entire subsector.

So, that because a "special needs" world, from the players' perspective, if they have a 2G ship. High tech, large pop, high-classed starport worlds will have a high port to serve all of the 1G traffic.

Worlds not has high tech or as high-classed with the starport (no high port) will probably have a system of 2G surface-to-orbit cargo shuttles. A 1G ship will make orbit then unload its cargo in zero-G. The shuttles will rendezvous in orbit to transport it dirtside. There may be a fee for this, but it might not be much as the fee could be subsidized by the World's government to incourage trade. Also, the shuttles could be drone piloted or totally robotic (as well as normal human operated shuttles and cargo handlers).

Worlds of low tech and no or low classed starports see the 1G vessel unloading cargo in orbit and using it's own launch to ferry it down to the surface. Typically, this isn't a normal run but done with high-prophet speculative cargo (not all of it legal).



I love all the "adventure" in that. It makes the universe seem more real.

So, yeah, I'll keep the Escape Velocity Promblem in my game.

 

[Supplement Four]

1G drives are the most common, but there may be only one size 9+ world in the entire subsector.

Knocking it up to a Size 9+ world (as opposed to the Size 8+ question from CT) really cuts down on the occurence. There are a lot more Size 8+ worlds than there are Size 9+.

As an example, I turn to the Regina subsector of the Spinward Marches in the Traveller Book.

Yres is Size A: BAC6773-7
Dentus is Size 9: C979500-A
Wochiers is Size A: EAC28CC-9
Moughas is Size A: CA5A588-B

Those four* worlds in the entire sector, and none of them are on a major X-Boat route (as the X-Boat routes are used as major trade lanes).

Looking at all the pecurliar conditions on these planets, you could get real creative about what it is like to visit these worlds using the Escape Velocity problem.

Of course, I enjoy "Reading a Subsector" (see my sig), and the EVP just adds more character to a section of space.





*If you use Size 8 worlds, as with the CT question, then the number of worlds in this subsector double as there are 4 systems with Size 8 main worlds.

 

[rancke]

Those four* worlds in the entire sector, and none of them are on a major X-Boat route (as the X-Boat routes are used as major trade lanes).

No they're not. Or at least, they shouldn't be. X-boat routes are mainly four-parsec jumps; major trade routes are mainly two-parsec jumps (and three-parsec jumps if you're in a High Guard ship design paradign universe). Trade networks and the X-boat network will overlap, of course, since the X-boats touch on important worlds and many important worlds are big trade worlds too. But you'll be getting practically no trade along the X-boat route through Lanth/Lanth, for example.


Hans

 

[aramis]

No they're not. Or at least, they shouldn't be. X-boat routes are mainly four-parsec jumps; major trade routes are mainly two-parsec jumps (and three-parsec jumps if you're in a High Guard ship design paradign universe). Trade networks and the X-boat network will overlap, of course, since the X-boats touch on important worlds and many important worlds are big trade worlds too. But you'll be getting practically no trade along the X-boat route through Lanth/Lanth, for example.


Hans

Cost per ton-parsec are significantly lower at J2 than J3 under HG.
It's Bk2 where the costs per ton-parsec are rather flat for 2-3 KTd ships between J1-J3.

 

[rancke]

Cost per ton-parsec are significantly lower at J2 than J3 under HG.

Not by my calculations. According to them jump-2 is about 3% cheaper (per parsec) than jump-3 for a 1000T ship.


Hans