Newsgroups: rec.games.frp.misc
Subject: Mistake on fusion drive
Summary:
Followup-To:
Distribution: world
Organization: UC Davis Dept of Applied Science at LLNL
Keywords: Traveller
I posted an article yesterday about the efficeincy of fusion drives.
Well, when I do the math again in the daylight, I find that the energy
yield for a fusion powerplant burning 1 m^3 of Hydrogen is 3 orders of
magnitude higher than my post suggested. A fusion plant of this type,
operating at 50% efficiency would have an output of:
2.27E10 MJ/m^3,
Thus a 1000 MW powerplant would take 2.27E7 seconds (262 days) to
consume 1 m^3 of fuel. This means it would be very easy to build a
powerplant with a 20 or 50 year duration.
unfortunatly, this also means the rocket velocity is going to .1 c.
Since this would result in an error in the classical figure of only
about 1%, I will use the classical figure anyway. It is
Vr=-2.53E7 m/s
This results in the fuel usage (in kg/s) going as:
dM/dt=Mi(1-exp(a*t/Vr))*(a/Vr)
Thus a fusion propelled 1000T vessel would require .14% of ships mass
for fuel (20 m^3) for 1 hour at 1g. for 1 day, it would take 3.3% of
ships mass for fuel (474 m^3). For 1 month at 1 g, 64.1% (9054 m^3).
If a ship was going to do alot of in system travelling, it might be able
to supplement it's fuel with a Bussard ramjet aproach. Of course, 30
days a 1g would put you half way to the next star system unless half of
it was spent slowing down. 15 days acc + 15 days decel would get you 111
Au out, Pluto is only 75 au out. so if your ship can carry 50% fuel, you
can get pretty much anywhere in the solar system in 30 days.
Now the real question; "Why is this important?"
Ans: Because this B.S. about jumping into a system 100 planetary
diameters out from your target sucks. It takes away all opportunities
for piracy. There is no reason each system couldn't just station a few
SDBs at critical locations, and completely police an entire system. If
you have to jump farther out, there are plenty of opportunities for
piracy - of course matching velocities can become a major problem.
"History shows again and Brian R. Jones
again how nature points DISCLAIM [email removed]
out the folly of men" THIS! ScumPuppy (netrek)
B.O.C. The Skaii, Sidhe (galaxy)