How fast can we go with STL? -- fast!!

[Tellon]

-- btw -- for those brave enough to check my math and make sure I didn't screw up would help too .. lol --

I was going over "Lightsecond chart" in FFS (pg 226-227) also seen as the Interplanetary Distance Matrix ...

So the chart is good for all sorts of orbits -- even Far companions -- say a Binary stellar or Trinary mix.

---

So the engine I am using is my HT version of the TL 9 Fusion Rocket (I'll also show the TNE version -- and thus one can see which one they want ...

HT TL 9 FR (Hard Times pg 84)
TT - 195 ======= 19,500 TT
wt - 4 ========= 400 tons
vol - 1 ========= 100 kl
Fuel - .005 ====== .5/h -> 21,915 kl (5 yrs)
F.wt - .07 ======= 1534.05 tons
F.Type - Liq Hyd
Pwr - [+3.9] ===== [+390 Mw]
pr - .35 Mcr ===== 35 Mcr

so obviously uses a lot of light weight fuel -- but that 5 yrs is awesome for long range flights

so now

TNE TL 9 FR (FFS pg 70)
TT - 9 -> 99 (x200) =============== 19,800 TT
wt - 1 (11x200) ================== 2200 tons (since each engine is 11 kl/11 tons)
vol - 1 (11x200)================== 2200 kl
Fuel - .00035 (x19,800 TT) -> 6.93/hr = 30,374.19 kl (6 months)
F.wt - .07 (x30,374.19) ============ 2126.1933 tons
F.Type - Liq Hyd
Pwr - TTx.02 ==================== [+396] Mw (it *is* a self-contained thruster)
pr - .35 Mcr (x2200 kl) ============= 770 Mcr

note*: The TT-9 for the rocket is the Minimum thrust for it -- so I can really crank up the TT's for our rocket engine; the fuel usage will skyrocket also -- so the TT's of thrust I multiplied by 22 so that my TT was nearly identicle to the HT ones above

The differences I see? .. the TNE using all those engines which take up wt & vol + the added fuel usage, and thus fuel wt -- so it all adds up.

So *this* is why I use the HT Fusion rocket compared to the TNE version -- although I could see the HT FR being say a TL 10 or 11 version of thre TNE FR.

----

OK -- so now for the real meat of my question ...

a light year = 31,557,600 seconds (60x60x24x365.25)

we want to use acceleration by G's section on FFS, pg 227

so -- let's say our Fusion Engines are burning at a constant 1G for a full month -- how much acceleration do we get -- and how many light seconds can we go?
1) (24x365.25)/12 -- should be 730.5 hrs in a month
2) we look at the Interplanetary Speed chart (pg 227) and see 8G & 18 seconds.
3) We know that 18 is 1/40th of 730.5 (basically) -- thus according to the rules ....
4) we divide 18 by 40 ... and get .45 of a minute to travel 1 light second (which is 18 seconds)

So my Far companion is right in the midddle of Orbit 15 & 16 -- right at 3731 AU -- or 1,837,950 ls

6) 1,837,950 x .45 = 827,077.5 min
7) 827,077.5/60 = 13,784.625 hrs
8) 13,874.625 /24 = 574.35937 days
9) 574.35937/365.25 = 1.5725 yrs

So to travel to a Far Companion is not bad at all: 1 mo burn to get up to speed -- then 1 mo in reverse to slow down -- so 2 months of fuel total use. (The TNE version of the FR would work fine for this kind of trip)

But now -- let see what we can do for a Parsec -- true Interstellar distances!!
(we would need to use the HT version of FR for this trip)

we will do a 1 yr long constant burn -- the acceleration should be pretty damn good.

8766 hrs/yr
we will use the 9G and 16 sec line
16 is 1/547th of 8766

so 16/547 = .02925 min/ls = 1.755 sec/ls (which comes to roughly 57% Light Speed --

31,557,600 x.02925 = 923,059.8 min = 15,384.33 hrs = 641.014 days = 1.755 yrs (for 1 LY)

which comes out to 5.265 yrs/Parsec [and only burning 2 years of fuel- so my 1st FR would have 3 left over once it go to its destination]

 

[robject]

http://eaglestone.pocketempires.com/scripts/vilanitools.html

30 days of 1G acceleration:

With deceleration:
Distance: 16796160000 km (112 AU)

No deceleration:
Distance: 33592320000 km (223.9 AU)
Velocity: 46656000 km/hr (52.3 AU/week)


30 days of 1G acceleration, followed by 30 days of deceleration, at 1G:
Distance: 67184640000 km (447.9 AU)



3731 AUs can be reached by 1G in 173d 4h 6m.


A full year of burn:

With deceleration:
Distance: 2486298240000 km (16575.3 AU)

No deceleration:
Distance: 4972596480000 km (33150.6 AU)
Velocity: 567648000 km/hr (635.8 AU/week)


Let me know if my script has errors.


So, you use HT because it gives better thrust at lower mass and fuel consumption rates than TNE? OK, but is that the only reason? Are the HT thrusters more appropriate for Traveller? Or, on the other hand, perhaps they're closer to current theories?

If it's just because they're better, couldn't we come up with something even better than them? Use some sort of souped-up drive whose fuel use is measured in decades, and still has appreciable thrust?

 

[Tellon]

Dunno -- The script looks ok from a cursory glance -- wish there was some explanation/details .. lol. I liked it how it split the straight acceleration and decel -- that was good.
-------------------------------------------------

Let's take a look at the 3 Fusion Rockets as an Evolution --

Say the TNE version as the TL 9 (base TL), the HT experimental one -- more as a TL11 one due to a BIG jump in fuel consumption, volume saved, cost -- and finally the TL 9 HT one which woiuld be say a TL 13 FR -- with savings on wt, better fuel consumption, cost and so on

so when we look at all 3 together -- I think we'd be looking at a series of developments in Fusion Rocket tech .. TL 9, 11, 13 (to give time for such a "jump" to occur and make the next step a worthwhile one

-- so for TU's that don't do Jump Drives, Thruster Plates, Gravitics, etc .. it helps a great deal...

so well lstart with the "worst" of the 3 -- the TNE one and go from there ..

Fusion Rocket
TT 9 (x11) = 99 (x200) = 19,800 TT
vol: 1x11 = 11 x 200 === 2200
wt: 1x11 = 11 x200 ==== 2200
F.Cons: .00035 x19,800 = 6.93 kl/hr = 30,374.16 (6 months)
F.wt: .07 x 30,374.19 === 2126.1933 tons
F.cost: 35 x 30,394.19 = 1.0631 Mcr
Pwr: TT x .02 = [+396 Mw]
Pr: .35 x 2200 = 770

Vol: 32,574.19
wt: 4,326.1933
pr: 771.0631
pwr: [+396]

Proposed TL 11 Fusion Rocket (using TL 8+ exp Rocket from HT)
TT 150 x 130 ======== 19500
vol: 5 x 130 ========= 650
wt: 20 x 130 ======== 2600
F.Cons: .005 x 130 === .65 kl/hr -> 28,489.5 (5 Yrs)
F.wt: .07 x 28,489.5 == .1994.365
F.cost: 35 x 28489.5 == .9971 Mcr
Pwr: .5 x 130 ======== [+65]
Pr: 2 x 130 ========== 260

vol: 29,139.5
wt: 4594.27
pr: 260.9971
pwr: [+65]

Proposed TL 13 Fusion ROcket (using TL 9 HT Fusion Rocket)
TT 195 x 100 ======== 19500
vol: 1 x 100 ========= 100
wt: 4 x 100 ========= 400
F.Cons: .005 x 100 ==== .5 kl/hr -> 21,915 (5 yrs)
F.wt: .07 x 21915 ===== 1534.05
F.cost: 35 x 21,915 === .767 Mcr
Pwr: 3.9 x 100 ======= [+390]
Pr: .35 x 100 ======== 35

vol: 22,015
wt: 1934.05
pr: 35.767
pwr: [+390]

********

So we can obviously see the progression between the Fusion Rockets -- it's just a matter of plugging in good solid #'s for F.Consumption, Cost, Engine volume & Weight [The 4 biggest factors as engines get better as new innovations come forth]

-- Now as far as why I chose the HT Fusion Rocket over the TNE one? .. I think it's pretty easy to see -- simple preformance (Fuel consumption, Engine vol, Engine wt, Price)

BUT -- for me -- let us say we have a MW at TL 9, while another MW is TL D, both make Fusion rockets -- which version would you buy for your Far Trader?

 

[Icosahedron]

I haven't checked, but I assume the charts in FFS and elsewhere are based on Newton's equations of motion.

If so, they are only useable up to a speed of around 0.1c. After that, they are decreasingly useful. For accelerations of a few days or possibly weeks, you're fine, you shouldn't have any problems doing a 6G burn from Mercury to Pluto, but when you try to cross interstellar distances (or possibly far companions) with constant acc burns of several months duration, you're gonna fall foul of relativity and you'll need some new equations/charts.

Light speed is 1AU per 8 mins, or 60AU per 8 hrs = 180AU per day = 1260AU per week approx, so any of your figures showing more than about 100AU per week are increasingly suspect. By 0.5c (600AU/wk) the figures will bear no relation to reality.

Just my Cr2.

 

[veltyen]

I haven't checked, but I assume the charts in FFS and elsewhere are based on Newton's equations of motion.

If so, they are only useable up to a speed of around 0.1c. After that, they are decreasingly useful.

Still accurate enough for most purposes though.

Dilation is M=M0/(sqrt(1-V^2/C^2)). If you express velocity as fractions of the speed of light then the V^2/C^2 just becomes V^2, which makes life a little easier.

At 0.1C M=1.005, meaning your 1 kilogram rest mass is now 1.005 kilogram (with matching time dilation). Yes that would mean some slight variation, but for basic ballpark physics not really that big a deal.

At 0.5C M=1.155 you do need to start taking it into account.

At 0.9C M=2.294 .... and all bets are off.

 

[robject]

Still accurate enough for most purposes though.

Indeed, this being an interstellar game, interstellar travel of some kind needs to get done without bogging everyone down too much. Fusion rockets are a nice way to get Niven's "Known Space" setting to work for Traveller.

 

[Tellon]

Light speed is 1AU per 8 mins, or 60AU per 8 hrs = 180AU per day = 1260AU per week approx, so any of your figures showing more than about 100AU per week are increasingly suspect. By 0.5c (600AU/wk) the figures will bear no relation to reality.

hmm, cool -- thx --

we know .12c works with Daedalus -- but yeah, when I saw .5 -- I was kinda going "Oh man, this might be so very wrong .. lol"

so .12c would be (acording to the AU above) around 150 AU/week. So ok, cool -- changes can be easily done -- thx

 

[Tellon]

Still accurate enough for most purposes though.

Dilation is M=M0/(sqrt(1-V^2/C^2)). If you express velocity as fractions of the speed of light then the V^2/C^2 just becomes V^2, which makes life a little easier.

At 0.1C M=1.005, meaning your 1 kilogram rest mass is now 1.005 kilogram (with matching time dilation). Yes that would mean some slight variation, but for basic ballpark physics not really that big a deal.

At 0.5C M=1.155 you do need to start taking it into account.

At 0.9C M=2.294 .... and all bets are off.

Thx -- I was wondering about the Mass/Time tweaks that went into the calcs .. very useful info..