System ship travel

Stormcrow's picture
Stormcrow
December 31, 2013 - 2:30pm
Has anyone worked out how long it takes a system ship to travel various distances, including acceleration and deceleration? I could use the ship travel calculations from GURPS Spaceships, but it would take some conversion. Even a simple rule of thumb would be welcome.

The rule on page 12 of the Knight Hawks campaign book about saving fuel by traveling at 10,000 km per hour is obviously wrong: going from Earth to the closest part of the middle of the asteroid belt at that speed, neglecting acceleration and deceleration, would take five and a half Frontier years.
Comments:

bossmoss's picture
bossmoss
December 31, 2013 - 3:25pm
I generally use existing science fiction novels as my baseline.  Heinlein or Asimov are good for this, since they were big on exactly this sort of detail (and a lot of Star Frontiers is based on their work).

Remember that Star Frontiers is meant to be kind of low-tech.  No Star Trek impulse speeds here, where you can just zip around a system in minutes or hours (impulse is about half light speed), but assume slightly faster than the modern day.

Currently in real life, it takes days to get to the moon, and a year or so to get to Mars.  The game is assuming speeds close to this.  However, as you point out, it's not very practical for game purposes.

In my game I allow ships to reach the closest planet in a matter of hours, usually the same day.  If we assume it takes 1 day to travel 1 AU (the distance from the Earth to the Sun), then we have a baseline for the rest of the system.  Mars, Venus & Mercury are all within 1 AU from Earth, so you can get to each of them the same day.  Jupiter is 5.2 AUs from the sun (and thus roughly 4 from Earth), so it would take 4 days to get from Earth to Jupiter.  By this system, Saturn is 8-9 days away, Uranus is 18-19 days out, Neptune is nearly a month away (almost 30 days), and it would take about 40 days to get to Pluto.

Hope this helps.

OnceFarOff's picture
OnceFarOff
December 31, 2013 - 3:29pm
I take a little more hand wavy approach. I usually allow for a day to get anywhere within a system. Fractions for partial distance. If I had a gun to my head, I'd say something like 1 AU per 4 hours or so. 

Shadow Shack's picture
Shadow Shack
December 31, 2013 - 4:42pm
I drafted some chem drive rules in the Historical Adventures project. IIRC they were in one of the SFman issues as well.
I'm not overly fond of Zeb's Guide...nor do I have any qualms stating why. Tongue out

My SF website

jedion357's picture
jedion357
December 31, 2013 - 4:43pm
Inner system to inner system is less time and inner system to outer system is more time, outer system to outer system is more time

honestly would be impossible to calculate IMO with out and accurate detailed map of a system and exact data on each body's orbital period and an accuract callender such that you could first determine overal position of each body then calculate distance while taking into account that each body is moving as well as the space craft. That's a lot of math and perhaps the only one that might enjoy it is Terl Obar.

I would suggest a rough dice mechanic based on Inner system to inner system, inner system to outer system, and outer system to outer system.

EDIT: or what shadow said

PS EDIT: astrogator skill check impacts ammount of fuel saved on the trip.
I might not be a dralasite, vrusk or yazirian but I do play one in Star Frontiers!

TerlObar's picture
TerlObar
January 1, 2014 - 12:31pm
There's no way to be consistent and realistic and not have it takes weeks or months.  If you start accelerating at 1 g and keep your engines on full time (i.e. as if making a void jump) it takes 83.3 hours (just over 4 days) to get to 0.01 c.  In that time, you've only traveled 3 AU.

So if you wanted to only accelrate a little bit, you're not going to have a lot of speed and it is going to take a long time to get anywhere.  Assuming you could accelerate at 1 g for 40 minutes (4 ADF), you'd have a speed of 24 km/s (that's less than the Earth's orbital speed around the sun BTW) or 86400 km/hr.  At that speed, the time to travel between the Earth and Venus at the distance of their closest approach is 521 hours or basically 26 days.

I think I did a write up on this in a discussion on ship engines somewhere on the site.  I'll have to find it.  But the bottome line is that space is very very big and it takes considerable speeds to get anywhere in short time scales.
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Tchklinxa's picture
Tchklinxa
January 3, 2014 - 7:43am
In the rules it says a large system ship can stay out for 1 year before returning to a base... so that would appear to be the max time for traveling about a system between refuel, resupply, inspection and maintance. So no distance from base to base should exceed 1 year.

On one of the other threads we talked about the fact that in RL natural objects move faster than the void jump speed in game, so the general thought line was that there are the engines which get you up to speed then a special void drive (ideas on how it worked and what the drive is varied) is activated and then the ship slips into the void.  

This then also allows for a ship to continue to accelerate past void speed if the drive is not activated... could be a plus or negative depending on situation. 








 "Never fire a laser at a mirror."

TerlObar's picture
TerlObar
January 3, 2014 - 10:02am
Yeah, I'm one of the ones strongly in favor of a "jump device".  If I were remaking the rules, that is what would distinguish a system system from a star ship.  Then you have the option/ability to run around the system in relative short time periods (days and weeks instead of weeks and months).
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Stormcrow's picture
Stormcrow
January 3, 2014 - 11:23am
The book says "a large research [system] ship can spend up to a year in space before returning to base"; it's not referring to system ships in general. I take this to mean a fully equipped scientific laboratory studying system phenomena can stay out a maximum of one (Frontier) year. Most system ships, even when trying to save fuel, won't take nearly this long.

I have seen many ideas for a "jump device" over the years, prompted by the idea that something needs to explain why natural objects moving faster than 1% the speed of light don't vanish into the Void. Such a device is unnecessary: the book says a ship reaching that speed enters the Void, not an object. Something about the electrical fields or composition or whatever about an artificial ship is what triggers the jump into the Void at that speed; no natural objects have the same property (or if they do, we can't see them because they're in the Void). In this case a ship cannot accelerate beyond 1% the speed of light within the normal universe.

Abub's picture
Abub
January 3, 2014 - 11:41am
If you do the Jump Drive thing in your setting it does make it so system ships can have Ion and Atomic drives as well... just not the expensive Void Drive device.

And depending on how the void drive works maybe you can upgrade a system ship... assuming something doesn't need to be integrated into the hull of the ship to like propogate the void field or whatever which could only be done at build time.

More and more I think I will use the jump drive idea.  I understand though that the void was supposed to have been discovered by accident from simple propultion tests.  You would have to modify that bit of "history" a little.

But I have a few players that will point out the natural particles moving more that 0.1c.  
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Putraack's picture
Putraack
January 3, 2014 - 1:06pm
From Traveller-- I got this from someone on either Citizens of the Imperium or Mongoose' forums.

The original formula is t = SQRT(2s/a), where t = time to midpoint in seconds, s = midpoint distance in meters, and a = acceleration in m/s^2.  This, of course, is for when you accelerate to about halfway there, then turnover the ship and decelerate the rest of the way.

If you change the time unit (T) to days, distance units (S) to AU, and acceleration (a) to Gs, then the TOTAL travel time is T= 2.835 * SQRT(S/a).

Or even T = 4 * SQRT(S/a) for the midpoint travel time, when S is the midpoint distance in AU.

Now, how far from planet A to planet B's moon? I must admit, I am surprised that no one has posted (canon or otherwise) orbital ranges for all the planets on the Frontier, given that there are only a few dozen systems. I've collected what I can find, and that's about half of them. Most of those system write-ups include average orbital distances for all the planets of a system. Someone around here did make up a random system generator, which I have printed off, and now misplaced. Embarassed So, Good ol' White Light System (from the WoWL module) shows Clarion at about 0.61 AU, Luminere and its 38 moons at 1.7 AU, and the outer edge of the asteroid belt just shy of 3 AU.

But, as we know, planets are in different places in their orbits all the time, and they move, too. One could work that all out themselves, which the Traveller guys have. (Seriously, look at http://www.utzig.com/cgi-bin/iai/map_top.pl-- the whole Imperium, mapped out. You can look inside a system on a given day and see how long to get from any point to another.)

Space:1889 to the rescue! Their formula was (4d6 - A - N) * D + N = L
D= 5% of average separation of the two worlds, in millions of miles, "which is always equal to 10% of the closer world's orbital distance."
A = astrogator's Astronomy skill, rated 1-6
D= various navigation aids, such as a telescope or an orrery
N = average separation between the two worlds, which is always the same as the farthest planet's distance from the system primary.
L = course length in millions of miles.

I should hope if all distances are re-done in AU, the formula should be the same? For Star Frontiers, I'd convert A into the course-plotter's (person or computer) Astrogation skill, and D into a straight 4.

If Mars is at 1.52 AU, and Venus is at 0.72 AU, the average separation is 1.52 AU. 5% of 1.52 is 0.076
Say Smedhurst has a skill of 3 and rolls 16. 16 - 3 - 4 = 9.
9 * 0.076 AU = 0.684 AU
0.684 + 1.52 = 2.204 AU This was the example in the book (p.131, for those following at home). The millions-of-miles conversion to AU is off by about 2% from that example. Close enough, I say. Tongue out


Abub's picture
Abub
January 3, 2014 - 1:10pm
Math is hard.


I say decide what you need for the narative and it takes at least that much time... and then don't worry about telling them time passes while that travel for days.
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bossmoss's picture
bossmoss
January 3, 2014 - 2:38pm
So you could travel between neighboring stars in a day or two, but between two neighboring planets in the same system might take weeks...

Tchklinxa's picture
Tchklinxa
January 3, 2014 - 3:09pm
Yes, it is "research vessel" but I imagine any properly prepaired large ship could, and in RL "research vessels" on the sea often are also Commercial Vessels doing something more then research. That is just my logic on that thought, plus it gives a logistics cut off point for what is the limit a system ship could do. So a system ship on a 5 year trip from station A to station X in a system would need to make pit stops at other system stations before reaching X in system.

Yes, per the rules the ships just slip into the void at the right speed... so staying true to SF Universe a system ship of any Engine type cannot achieve the speed so must fall short of the 1% speed as it's max speed, both Chemical and Ion ships have an ADF of 1. Also per rules 1% of speed of light is about 12 million km per hour, that means system ships can get close to this speed but not exceed it in theory. The game also says there is no max speed for ships in the combat rules.

But I have been crunching numbers and Speed of Light is 300,000 km per second, and an hour is 3,600 seconds so in an hour at the Speed of Light you will have gone 1,080,000,000 kms that means you are travel at 1% 10,800,000 km per hour not 12 million per hour (assuming what info I am scrounging off the net is right and my rusty math is right).

1AU is about 149,597,870.7 km often rounded up to 149.6 x 10 to the power of 6 and 1AU is the distance light travels which equals 8 minutes and 3 seconds. The Speed of Light covers 173 AU's per day. So 1% speed would equal 1.73 AUs per 24 hour day. If the 12 million per km is the actual speed a ship needs to achieve to enter void then we have some wiggle room I think for system ships.

1ADF equals 10,000 km in 10 minutes which equals 60,000 km per hour this means it would take at 1ADF 2,493.29783333... hours to travel 1AU or about 103-4 Earth days or between 124-125 SF Days.
But every 10 minutes the ship can go faster so if the ship was inceasing it's speed at 1ADF each turn for an hour the ship has now traveled 210,000 km in 1 hour in the 2 hour it will cover 570,000 kms for a total of 780,000 km covered in 2 hours. So on the third hour the ship will have covered an additional 930,000 km add the previous distance covered and we have now gone 1,710,000 km in 3 hours the ship is right now traveling at 18ADF which is 180,000 km per 10 minutes or 10,800,000 km per hour which is the actual 1% Speed of Light. Now to reach 12 million km per hour the ship would need to hit 20 ADF. So I would guess a system ship should never ever for what ever reason be able to go past 19 ADF for game purposes, and for safety reasons 18 ADF is probably the fastest speed legally should be allowed to go by authority/regulating entities the "space fuzz". So this system ship would probably stop accelerating at 18 ADF and now continue to cruise at that speed traveling an additional 10,800,000 km per hour every hour so by the 11th hour the ship should have covered 66,510,000 km so that means the ship will be at the half way point durring the twelth hour and it will have gone 77,310,000 km at the end of that hour. This means that you can fudge your math a bit here I think and figure it takes about 23 to 24 hours to go 1 AU in a ship with 1ADF.

I hope this math was right enough for game play and makes sense.

It is then a matter of figuring out how many AU's to object in the system mostely.  
 


 

 
 "Never fire a laser at a mirror."

TerlObar's picture
TerlObar
January 3, 2014 - 3:57pm
I think you're off by an order of magnitude (factor of 10) somewhere but I'm not seeing it right off.  Void speed is 180 hexes per turn not 18.  (c= 300,000 km/s, 0.01c= 3,000 km/s 1 game turn = 600 seconds.  0.01c = 3000x600 = 1800000 km/turn, 1 hex = 10,000 km so 0.01 c = 1,800,000/10,000 = 180 hexes).  Remember that ADF is an acceleration not a speed.  (And as has been noted in many places on this forum and around the web, the numbers are inconsistent between the Campaign book and the boardgame rules.)
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Sargonarhes's picture
Sargonarhes
January 3, 2014 - 6:20pm
This is very much like the difference back in the frontier days of the Americas if you think about it. You can get to some locations faster by ocean going ship than you can across land. Or even use the old west and think of the nuclear powered ships as the train locomotives, sure they're fast but they don't travel everywhere. No expensive interstellar capable ship is going to jump to every planet or base within a system unless they're looking to avoid maybe the local crime boss or officials. Most of these will jump into a system and go right for the primary planet, as I said unless they're trying to avoid something.

So for comparing it to the old west you get off the train saddle up your horse and ride to whatever location, more like sneak in if you're avoiding trouble. This creates a whole new series of game scenarios if you look at it this way. It can also mean station outposts run by corporate or even criminal bosses. Independant mineing ships stakeing their claim because there's gold in them thar asteroids.

There's also the probability that a system ship has a good haul and might burn more fuel to get back faster than just drifting most of the trip, cutting travel time down a bit more. Can see station control asking "Who's that idiot coming in breaking like mad? They're going to exhaust all their fuel doing that." Put the calculators away for a bit and just have fun with it.
In every age, in every place, the deeds of men remain the same.

Tchklinxa's picture
Tchklinxa
January 3, 2014 - 7:31pm
I messed the math up, I was interrupted a tons of times while I was trying to crunch the numbers... and then I had to leave so I posted and hoped I had not made a mistake: I also realized in the grocery I should have put hexes and not ADF for ship speed.

I think I followed this logic:

  c = 300,000 km/s and then I multiplied by 60 to get 18,000,000 km/m which I multiplied by another 60 to get 1,080,000,000 km/hr. I probably divided that figure by 10,000 to get number of hexes covered being 108,000 at light speed.   Now I think I multiplied .01 with 1,080,000,000 = 10,800,000 km/hr being the 1%c speed at which point I probably divided that by 10,000 and should have gotten 1,080 hexes covered at 1%c. So I should have divided 1,080 by 6 to get hex speed per turn which should have been 180 hexes also. Hum. I have no clue what I did to end up with 18 which is clearly wrong no matter how you figure it.   

But the books also specifically states about 12 million km per hour is when the ships enter Void as well. So that would be 1,200 hexes being covered in an hour. I believe if I divide 1,200 by 6 then we get 200 hexes. Giving us 2 potential numbers for Void Speed 180 or 200.     

So I am reworking me figures on a ship going 1ADF each turn needs to go accelerating and then decelerating to travel 1AU again.   
 "Never fire a laser at a mirror."

Shadow Shack's picture
Shadow Shack
January 3, 2014 - 9:32pm
Stormcrow wrote:
The book says "a large research [system] ship can spend up to a year in space before returning to base"; it's not referring to system ships in general.

P.14 of the KH Campaign Book states that the life support needs to be replenished every 6 months. There's your limit...the research ship probably has extensive LS so that it can stay out longer but the standard ships (system or star ships) will have the six month span to contend with. 
I'm not overly fond of Zeb's Guide...nor do I have any qualms stating why. Tongue out

My SF website

Stormcrow's picture
Stormcrow
January 3, 2014 - 11:09pm
Rather than keeping track of where various planets are in their orbits—that would be a nightmare—you can settle for averages.

Take the situation of two planets orbiting a star. For simplicity assume perfectly circular orbits. Planet A orbits X km from the star; planet B orbits Y km from the star; Y > X. The farthest the two planets ever are from each other is when they are on opposite sides of the star, all in a straight line in two dimensions: the distance is X + Y. The closest the two planets ever are to each other is when they are on the same side of the star in a straight line: the distance is Y-X. The average distance between the two planets is therefore [(X + Y) + (Y - X)] / 2 = 2Y / 2 = Y. Thus, the orbital distance of the outermost of two planets is always the average distance between two planets.

Therefore, if you want to simply use averages all the time, calculate the time it takes to travel the distance from the star to the outer planet of the journey; that's the average time it takes to travel from one planet to another.

The only issue is, of course, figuring out how long it takes a ship with 1 ADF to travel the distance Y.

So if we know that Inner Reach is 143 million km from Dramune and Outer Reach is 175 million km from Dramune, we know that the average travel time between the two planets will be however long it takes to travel 175 million km.

Tchklinxa's picture
Tchklinxa
January 4, 2014 - 11:23am
I believe in logical but simple for game play... only because I want more action happening and do not like frustrating people with math... so average distances is what I plan to use as well probably rounding numbers to get general times. But I want it to be consistent with the rules too. 

I started recalculating what a rough figure might be for a ship with 1ADF /1MR to travel 1AU.

So if 1AU = 149,597,870.7 km = 14,960 hexes, then 1/2AU = 74,798,935.35 km = 7,480 hexes.

I crunched the numbers and at the end of Hour 20 the ship is going 120 hexes and has just finished moving 7,260 hexes in total, which is 220 hexes less then the half way point.  So I am figuring maybe around 40 hours to go 1AU or 2 SF Days.

Now the ship I think would have to start to decelerate and flip around. It seems if I understand the description on pg. 33 KH Exp the ship first spends several minutes at 0 g maneuvering around and once flipped around then starts to decelerate. 

If the ship had a 1MR the question is how would it turn? The combat rules remind me a lot of old Star Fleet rules, in that they ignore 3-D space; the old ST rules said a ship could not do barrel roles or flip around because everyone would fall or get killed or something like that it seems to me; so would the ship have to make a 2-D turn turn and then hit the brakes or could it do a 3-D turn? It seems the description is implying a more 3-D move of going straight and tumbling into position (there is an old Bi-plane board/rpg game that had rules for moves like that). So if the ship can turn only one hex-side in any hex that is a huge U-Turn left or right in 2-D before decelerating 4 x 120 = 480 hexes, but if you imagine a hex space as 3-D on the hex board the ship would move forward 120 angled up, vertical 120, and then angled back 120 and finally finnish leveled off another 120 on a straight line, it is still a 480 move over 4 turns but the ship ends up from where it started facing the opposite direction but moved up 360 spaces above where it was. So this is a 40 minute action. But thinking on how to get the ship back on trajectory it seems it would move angle down decelerating until it has covered 360 hexes. In three turns decelerating 1ADF it would have covered 354 hexes pretty close to the 360 so figure another 30 minutes. So, it takes about 1 hour and 10 minutes to do all this then?

Most of the maneuvering would be with everyone all comfy at 0 g except for the return to trajectory which would be one angle down and one level off while decelerating this makes more sense to me per the description and the speeds being covered. 

Do you guys think I am conceptualizing this right? I wish I could remember the name of that Bi-plane game now...

I am now figuring based on the corrected math I will not allow system ships to exceed 180 for fastest speed (though I will work up something for 190 in case someone wants to risk a fine from the "space fuzz"). I am using the 200 hex speed as the magic number for entering the Void.




 "Never fire a laser at a mirror."

Stormcrow's picture
Stormcrow
January 4, 2014 - 4:27pm
Okay, I have done the math—I don't have it in a plug-in formula for you to see—and I have come up with an average time of about 52 hours, or about two and a half Frontier days, to get from Inner Reach to Outer Reach. That assumes an acceleration of 1g, headed in a straight line, and with 1g decleration begun at the midpoint of the trip. It negelects the orbital velocities of the planets and the time it takes to turn around.

At ADF 1—almost 3 g—the same trip would take about 30 hours, or one and a half Frontier days.

If you don't want to do the math every time, you can take this as some benchmark numbers.

I'm not prepared to start playing with delta-v to determine how to end up with only half your fuel used.

Tchklinxa's picture
Tchklinxa
January 4, 2014 - 5:17pm
I have crunched numbers just straight acceleration no slow down point yet to get an idea on how many hours it would take before Void Speed.

In my case Void Speed is hit at 200 hex speed; I am considering 1%c the safety stop point = 180 hex speed; I am figuring any system ship exceeding 180 is breaking laws, running all sorts of mechanical risks each turn at any speed over 180 and at 200 it either misjumps into a blackhole or something else bad if engines are the right type or it simply blows the hell up.

At the end of Hour 30 speed 180 is hit. Hour 33 and 2 Turns Void speed is achieved. Assuming I did not mess up the math:

So here is what I got so far:

1ADF Ships at nonstop acceleration:

Hour 1: 1,2,3,4,5,6 = 21 = 210,000 km   
Hour 2: 7,8,9,10,11,12 = 57 + 21 = 78 hexes = 780,000 km   
Hour 3: 13,14,15,16,17,18 = 93 + 78 = 171 hexes = 1,710,000 km   
Hour 4: 19,20,21,22,23,24 = 129 + 171 = 300 hexes = 3,000,000 km  
Hour 5: 25,26,27,28,29,30 = 165 + 300 = 465 hexes = 4,650,000 km  
Hour 6: 31,32,33,34,35,36 = 201 + 465 = 666 hexes = 6,660,000 km   
Hour 7: 37,38,39,40,41,42 = 237 + 666 = 903 hexes = 9,030,000 km   
Hour 8: 43,44,45,46,47,48 = 273 + 903 = 1,176 hexes = 11,760,000 km   
Hour 9: 49,50,51,52,53,54 = 309 + 1,176 = 1,485 hexes = 14,850,000 km   
Hour 10: 55,56,57,58,59,60 = 345 + 1,485 = 1,830  hexes = 18,300,000 km   
Hour 11: 61,62,63,64,65,66 = 381 + 1,830 = 2,211 hexes =  22,110,000 km   
Hour 12: 67,68,69,70,71,72 = 417 + 2,211 = 2,628 hexes = 26,280,000 km   
Hour 13: 73,74,75,76,77,78 = 453 + 2,628 = 3,081 hexes = 30,810,000 km   
Hour 14: 79,80,81,82,83,84 = 489 + 3,081 = 3,570 hexes = 35,700,000 km   
Hour 15: 85,86,87,88,89,90 = 525 + 3,570 = 4,095 hexes = 40,950,000 km   
Hour 16: 91,92,93,94,95,96 = 561 + 4,095 = 4,656 hexes = 46,560,000 km   
Hour 17: 97,98,99,100,101,102 = 597 + 4,656 = 5,253 hexes = 52,530,000 km  
Hour 18: 103,104,105,106,107,108 = 633 + 5,253 = 5,886 hexes = 58,860,000 km   
Hour 19: 109,110,111,112,113,114 = 669 + 5,886 = 6,555 hexes = 65,550,000 km   
Hour 20: 115,116,117,118,119,120 = 705 + 6,555 = 7,260 hexes = 72,600,000 km   
Hour 21: 121,122,123,124,125,126 = 741 + 7,260 = 8,001 hexes = 80,010,000 km   
Hour 22: 127,128,129,130,131,132 = 777 + 8,001 = 8,778 hexes = 87,780,000 km   
Hour 23: 133,134,135,136,137,138 = 813 + 8,778 = 9,591 hexes = 95,910,000 km   
Hour 24: 139,140,141,142,143,144 = 849 + 9,591 = 10,440 hexes = 104,400,000 km   
Hour 25: 145,146,147,148,149,150 = 885 + 10,440 = 11,325 hexes = 113,250,000 km   
Hour 26: 151,152,153,154,155,156 = 921 + 11,325 = 12, 246 hexes = 122,460,000 km   
Hour 27: 157,158,159,160,161,162 = 957 + 12,246 = 13,203 hexes = 132,030,000 km   
Hour 28: 163,164,165,166,167,168 = 993 + 13,203 = 14,196 hexes = 141,960,000 km   
Hour 29: 169,170,171,172,173,174 = 1,029 + 14,196 = 15,225 hexes = 152,250,000 km   
Hour 30: 175,176,177,178,179,180 = 1,065 + 15,225 = 16,290 hexes = 162,900,000 km    
Hour 31: 181,182,183,184,185,186 = 1,101 + 16,290 = 17,391 hexes = 173,910,000 km   
Hour 32: 187,188,189,190,191,192= 1,137 + 17,391 = 18,528 hexes = 185,280,000 km   
Hour 33: 193,194,195,196,197,198= 1,173 + 18,528 = 19,701 hexes = 197,010,000 km   
Hour 34: 199, (200=Void) = 199 + 19,701 = 19,900 hexes = 199,000,000 km         

Does this look right folks?

 "Never fire a laser at a mirror."

Stormcrow's picture
Stormcrow
January 4, 2014 - 6:12pm
That's the hard way to do it. I just used some algebra.

1 ADF is almost 3g.

Void speed is 180 hexes per turn.

A ship accelerating at 1g from speed 0 requires 85 hours to reach 180 hexes per turn, or just over 4 Frontier days.

This would mean that the shortest possible trip from one system to another at 1 g is 8 days. However, there are known routes that are shorter than this, and it seems unlikely that passengers would be subjected to higher accelerations. Clearly, the 0.01c is bogus, even if you posit a "jump drive."

After 85 hours of 1g acceleration, you'd have traveled approximately 91,800 hexes, or about 918,000,000 km. This is about the distance from the sun to a point between Jupiter and Saturn.

This is more than enough for system travel, so there's no danger of system ships of accidentally entering the Void. Since system ships can't enter the Void, they obviously can't accelerate for this long.

Tchklinxa's picture
Tchklinxa
January 4, 2014 - 7:53pm
So if I multiply the times by three that should give me the 1g speed? So if a ship is going 1g and working up to 1ADF it will take 30 minutes (3 Turns) to end at 1 hex speed increase. 2g accelertaion would be times 2? Takes 20 minutes (2 Turns) to end at 1 hex speed increase. 

So my chart works for the out of control ship or someone trying to do a runner from the space fuzz...lol.

Okay what are the effects of 1MR? I imagine turning creates g forces too. Is it a similar effect?

 
 "Never fire a laser at a mirror."

TerlObar's picture
TerlObar
January 5, 2014 - 8:55am
The exact ratio between 1g and 1 ADF is 2.777777777777777777 Foot in mouth (just use 2.78 or round to 3). 

MR is completely unrealistic but makes for a playable board game (althought the vector rules we published in Star Frontiersman 11 are completely realistic and are quite playable).  e.g. to do a 180 degree turn in the boardgame requires 3 MR, a destroyer or smaller craft can do it in a turn.  But in real life, to turn around like that, you'd have to kill all of your forward velocity and then accelerate back up to speed in the new direction. If traveling at a high rate of speed, that could take a long time.

As for turning the ship around, that's pretty straightforward.  You just fire your maneuvering jets to rotate the ship.  You're still going to be going in the same direction but now you're traveling backwards.  Think about an ice skater that is skating foward, does a jump, and is suddenly going backwards but still in the same direction.  It's the same idea.  You can do it either with or without your engines on.  If you do it with the engines off, everyone is in zero g for a bit and you literally rotate in place.  If you do it with the main engines off, you trace out a little curve but it won't be that big compared to your total traveling speed.

As for the time needed, I once looked at it for a Star Frontiers plugin for the Orbiter space simulator that I was working on and figured that the smaller military vessels could turn around is under 30 seconds and never even notice any significant sideways acceleration.  A battleship (HS 20) could do a 180 in about 3 minutes (or maybe it was 90 seconds) and only experience a 0.5 m/s^2 (0.05g) acceleration sideways (I think it was 0.5 m/s^2 and not 0.5g.  It's been several years).  The point is, you can turn the ships fairly quickly so taking a few minutes to do so is no big deal and will not cause any strain on the passengers.  And you just pivot in place and now your engines are firing in a different direction slowing you down.
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Tchklinxa
January 5, 2014 - 12:17pm
Thanks guys, I will use rounded numbers on the gs.

I will check out SFM11.

Maybe I will go up to flight time simulators at my volunteer gig and have the pilots pull up the Space Shuttle so I can get a good idea of it. Probably will have to have them help me a lot... the time I tried to fly the "easy" Cessna simulation did not end well, I finally had to use my pinky fingers 'cause I am use to having to use serious force to steer. There was a lot of "Dear God! Gentle!" shouting. LOL  I did get better. :) 
 "Never fire a laser at a mirror."

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TerlObar
January 6, 2014 - 6:09am
If you wanted to play with flying an Assault Scout around, grab the Orbiter simumulator and the Frontier: 55 Cancri plug in.  The Orbiter software is at http://orbit.medphys.ucl.ac.uk/index.html and the plugin can be downloaded in the Downloadables section of http://starfrontiers.org

The plugin is pretty old and I don't know if it still works with newer version of orbiter but if not, I could send you a copy of an older version it does work with.  Then you could fly around and get a feel for timings.

I also have a mod that implemented most of the weapons and the damage system from Star Frontiers that we never quite finished.  I think all it doesn't do is seeker missiles and mines.  But it's been several years and I'm a bit fuzzy on what it does and doesn't do.
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Tchklinxa
January 6, 2014 - 10:37am
I sent the link to my hubby, he should be able to download as his lap top is Windows. My computer is Apple.



 "Never fire a laser at a mirror."

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TerlObar
January 6, 2014 - 10:00pm
Tchklinxa wrote:
My computer is Apple.

I'm sorry.  Foot in mouth

I use all flavors of computers at work (Linux, Apple, Windows) and by and far Apples give me the biggest headaches.  They're great computers, just not for what I need them to do. which, I admit, is definitely far outside the Apple design model.
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Tchklinxa
January 7, 2014 - 5:29am
I like my Apple but it does have program limitations. 

I will be down at the Aerospace Museum today at break (barring any surprise work load) and I will find out what I need to do with the instructors at the flight center to log hours on the Space Shuttle. Smile 




 "Never fire a laser at a mirror."

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TerlObar
January 7, 2014 - 6:19am
Sounds fun.  While the shuttle doesn't have anything near the engine power of most KH ships, flying it around will give you a good feel for how ships maneuver in space.

Just out of curiosity, which Aerospace Museum?  When I read that, I immediately thought of the Smithsonian in DC (I happen to be in National Harbor at the moment for the American Astronomical Society meeting and will be in Greenbelt at NASA Goddard later in the week).
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