Travel times for system ships

KRingway's picture
KRingway
September 10, 2019 - 5:26am
For the life of me I can't remember if there are any distinct rules for the time needed for a system ship to travel X amount of distance. I'd like to think that this type of ship is faster in SF than in it is in our current time, but I don't know if that's possible. KH states that these ships have chemical drives, but I was wondering if they could have an ion drive instead - possibly if it made them faster.

I ask as I have an adventure in development where I want the players to travel in a CDC system ship to an asteroid belt at the edge of a system. I wasn't sure how long this would take, but was imagining an HS:4 ship that either has chemical or an ion drives.
Comments:

KRingway's picture
KRingway
September 11, 2019 - 6:06am
So, judging by a discussion about this over at the MeWe SF group, there aren't any rules dictating how fast ships travel within a system. KH doesn't cover this, as it's only interested in interstallar travel, not intrasystem. So there's a gap there in our picture. It seems speed is only relevant really WRT combat and, although that's possibly within a system, it doesn't give a hint about how fast a ship can travel generally when not in combat or to and from a jump.

I do wonder if it's possible to generate some numbers and speeds based on a ships ADF, but I don't know how feasible that is...

Any ideas?

jedion357's picture
jedion357
September 11, 2019 - 5:35pm
I would say that the CDC would just spring for the expense of an ION drive and be done with it. Ssytem ships are just slow. and corporation would just dispense with them and employ ion drives as system ships for the speed and flexibility they offer.
I might not be a dralasite, vrusk or yazirian but I do play one in Star Frontiers!

KRingway's picture
KRingway
September 11, 2019 - 9:35pm
There's still a gap in the way things work though. If a ion drive is 'slow' (ADF 1) what exactly does that mean in terms of how long it takes to get from A to B in a system? It also suggests that atomic drives are faster, possibly also chemical drives, but we're not told by how much. There's mention of chemical drives being able to travel at 10,000 kph so that they can make a round trip on one fuel load, but that's extremely slow and the time/distance of a round trip is not given.

Anyway, it might be a fun exercise to design this system ship for a Frontier Explorer article. I think I'll just have to say that the ship takes 'a few days' to get to the asteroid belt. It's going there to find an NPC ship. I've also worked up a quick doodle of this:


iggy's picture
iggy
September 11, 2019 - 10:59pm
Terlobar and I have done the math before that converts ADF to metric units and then the travel times can be done.  There are a few threads on this site with good write ups by Terlobar.  This may also be on his website as an article too.

Tell me how far you want to go and the acceleration you want to have the players endure and I can calculate it for you.  If I remember one ADF is more than 1G of acceleration and hard to endure for long durations.
-iggy

iggy's picture
iggy
September 11, 2019 - 10:59pm
I like your ship drawing.
-iggy

KRingway's picture
KRingway
September 12, 2019 - 1:05am
I want to keep things simple, so possibly it's a straight run to the asteroid at 1G. I've invented an asteroid belt within the Madderley's Star system, as the adventure starts on Kdikit. I've no idea what the distance would be.

JCab747's picture
JCab747
September 13, 2019 - 12:39pm
Interesting topic. I would think a chem drive ship just accelerates to the equivalent of 1 hex a turn and then just coasts, using fuel for various course corrections and then decelerating. Now, hopefully it has enough fuel for a return trip to its destination!
Joe Cabadas

Stormcrow's picture
Stormcrow
September 13, 2019 - 5:37pm
Yes, a system ship certainly can't accelerate its entire journey, or else it would have enough fuel to jump into the Void.

They probably didn't include system travel times because calculating those is really hairy. What are the orbital velocities of your start and destination? It's supposed to use one load of fuel to make one trip; how much delta-V can a chemical drive produce?

Fortunately, this sort of thing can be hand-waved by the referee. "The trip will take four months." "Four months! But last time it only took two weeks!" "That was three months ago. Inner Reach is on the other side of Dramune now."

I would tend to err on the side of shorter travel times, assuming Frontier chemical engines are much better than anything we have.

KRingway's picture
KRingway
September 14, 2019 - 12:15am
Going by the discussion over at MeWe, chem drives aren't very practical just becaue of the amount of fuel that has to be taken with them to get any distance. Ion drives seem like a better option, as they can carry a lot of fuel. So I may go with that option - possibly there's a chance for a slightly new ion engine design, that has a limiter so that it can't reach the speeds needed for a jump.

But maybe that's just too much detail. I think I'l just say that there's an asteroid belt in the system (Madderleys Star) and it takes 2 days to get via system to ship from Kdikit.

In the meantime, here's some more quick doodles - the second image is the NPC ship that the players will be looking for, a dralasite design:



JCab747's picture
JCab747
September 14, 2019 - 9:32am
Slap me upside the head! I believe the 2001 and 2010 Space Odyssey modules provide a few rudimentary rules for, shall we say, primative system ships.

The 2001 module provides the new Star Frontiers skill of Astronomy (hmm, sounds a bid Zebs like), and system navigation for plotting courses within a system.

On a star map, "the Leonov can move into any adjacent hex on map 8 every 6 hours. After the Discovery is repaired in chapter 3, it too, can move into any adjacent hex every 6 hours..."

The scale on map six is one hex = 100,000 kilometers... Isn't that 10 times the size of a Knight Hawks hex? 

The rules also provide info on aerobraking in Jupiter's atmosphere and using Jupiter's gravity to slingshot back toward Earth.

Again, one could view these as rules for very out of date system ships, but they provide a few ideas.



Joe Cabadas

JCab747's picture
JCab747
September 14, 2019 - 10:42am
but, I would agree that chem drives seem particularly slow for interplanetary travel except for those who can't afford a better ship.
Joe Cabadas

KRingway's picture
KRingway
September 14, 2019 - 12:03pm
Hehe - I avoided the 2001/2010 adventures like a bad smell as I didn't like the movies (and still don't). But it sounds like they may have their uses. Then again, even if chem drives in SF are waaaaaaay better than anything we know of here on Earth, and maybe also with some super-fuel that we don't have, maybe they're useable in some way as system ships with people inside who don't want to spend their whole lifetime getting from one place to the next...

JCab747's picture
JCab747
September 14, 2019 - 12:50pm
KRingway wrote:
Hehe - I avoided the 2001/2010 adventures like a bad smell as I didn't like the movies (and still don't). But it sounds like they may have their uses. Then again, even if chem drives in SF are waaaaaaay better than anything we know of here on Earth, and maybe also with some super-fuel that we don't have, maybe they're useable in some way as system ships with people inside who don't want to spend their whole lifetime getting from one place to the next...
 

Understood, but, yess the modules have some interesting things that can be incorporated into the game such as a luner exploration vehicle and the like. I used to own the modules (along with all the rest of the pieces of the original game), though I never had a chance to use them... The 2001 module has a place where you can play ape men... I think I would have avoided that. 
Joe Cabadas

JCab747's picture
JCab747
September 14, 2019 - 12:53pm
I would say, chem drives for surface to space, space to surface takeoffs and landings and an ion drive for system travel. The Knight Hawks rules don't exactly prohibit a ship from having two types of drives, do they? Of course, they don't explain how tugs can be used or the particulars of Ag ships that seem to violate the construction rules either.
Joe Cabadas

KRingway's picture
KRingway
September 14, 2019 - 2:22pm
Yep, one idea would be that ships with ion drives carry a bolt-on chem drive to get them to and from a planet's surface, if their HS is small enough. Possibly these could use the same fuel rate rules as shuttles, plus some tweaking to take into account the size difference - i.e. a modifier based on HS. If a ship doesn't have one installed, perhaps a kit can be rented - it's bolted on in orbit once the ship arrives, is replenished on the ground, and then after the surface to orbit trip back out the kit is discarded for reuse by the rental company. This of course only works in there's suitable facilities for this in orbit and on the surface.

JCab747's picture
JCab747
September 14, 2019 - 4:14pm
I like the bolt on chem drive!
Joe Cabadas

KRingway's picture
KRingway
September 14, 2019 - 11:02pm
It's still a bit handwavey, but so is quite a lot of things in SF.