On 02/05/07, Roger Burton West <[EMAIL PROTECTED]> wrote:
On Wed, May 02, 2007 at 05:54:22AM -0400, DataPacRat wrote:
>The current design I'm fiddling with is 83% fuel. I suppose if the
>fission-fragment has the best Isp, the only options I have left are to
>increase the fuel-to-payload ratio, and/or use some staging to get rid
>of some of the unnecessary structural mass in mid-thrust.
That seems like a very low fuel fraction; designs I've heard about are
99% or more.
Hm, okay.
After some further fiddling, I arrive at these numbers:
* engine: 420,000,200 lbs
* fuel: 8,400,004 lbs gives Burn Endurance of 8,000 hours
* 50,000,000,000 lbs fuel gives Burn Endurance of 47,619,024.9 hours
= 5,432.33379 years
* Thrust: 300,000 lbs
* LWt: 50,698,137,445 lbs
* Delta-Vee:
21.8 * 1,000,000 * ln (1+(50,000,000,000/698,137,445)) miles/hour in
metres/second = 41,761,573.9 meters / second
2.15 lightyears / (0.5 * 41,761,573.9 meters / second) in years
= 30.8682707 years
* 2 = total trip time of 61 years.
... which is certainly under a century. :)
The hard part /now/ is figuring out how to arrange for the engine to
burn all its fuel within the actual trip time. (Oh, and it wouldn't be
a bad thing if I could reduce the cost from a quarter quadrillion
dollars, either, but I'm not holding my breath on that one. :) )
>(My mistake in typing that out - that's supposed to be fully-loaded
>sAccel times burn-time.)
Of course, you should also bear in mind that the mass of the drive will
be a factor - you may want to stick with Orions in the end, because that
f-f thruster itself weighs 140lb/lbthr as opposed to 0.125lb/lbthr for
the Orion. Certainly worth considering both.
And such consideration is why I'm here. :)
>I'm not quite up to fiddling with GVB's formulas in that manner yet. :)
It's really easy. Trust me on this.
(1) Make sure your drive and fuel tank are in the same subassembly (or
package).
(2) Right-click the package and select "new link node".
(3) Select in the four list windows: the drive, "vFUEL_WEIGHT", the
fuel, "TotalPayload". Leave the multiplier at 1.
That's all it takes, and you'll get an accurate delta_V readout.
... for, it seems, any drive /but/ Orion or fission fragment. :)
In case anyone's curious, here's the current GVB stats:
-----8<-----
TL8 interstellar ship
Crew: 6 total. 3 crew stations covering 3 vehicle maneuvering systems,
6 communicators, 6 navigation aids, 12 sensors. 3 medics.
Subassemblies: Vehicle +17, Body +17.
P&P: 6,000,000 sf solar cell [Vehicle], three 2,000-kW fission
reactors (2 year duration; long term access), 300,000 lbs. thrust
fission fragment thruster (Isp 0, delta-V 0 mph; long term access).
Fuel: 6,667 gal fissionables.
Occ: three roomy crew stations (bridge access, crashweb, g-seat), two
luxury extra space cabins (2,000 cf extra total), 20 cabins, three
24-man total life support systems Cargo: 30,000-cf cargo hold w/cargo
density 20-lbs/cf
Armor F RL B T U
Body 4/100 4/100 4/100 4/100 4/100
Equipment
All: self-sealing hull. Body: three complete workshops; three full
fire suppression systems; fissionables processor (10 lbs. per hr
processed); fission fragment fuel; operating room (three tables w/full
stabilization); three emergency support units; six AESAs (scan 29,
1,000-mile range; LPI); six PESAs (scan 29, 1,000-mile range);
cartography program (C3); computer navigation program (C2); +2 damage
control program (C2); datalink program (C1); full personality
simulation program (C5); routine vehicle operation program
(piloting-15, C5); three mainframe computers (complexity 5; hardened,
high capacity, neural net, robot brain); three computer terminals;
three inertial navigation systems; three sets of precision navigation
instruments; three advanced radiation detectors; three extreme range
laser communicators (200,000-mile range; scrambler); three extreme
range radio communicators (100,000-mile range; scrambler); set of
astronomical instruments; geology survey array; laser chemscanner
(100,000 yd. range); life detection package; magnetometer; high
resolution planetary survey array; three 2-man airlocks (shower);
three science labs; metal armor volume.
Statistics
Size: [LxWxH] 3,202'x800'x400' Payload: 600,600 lbs. Lwt.: 50,698,137,445
lbs.
Volume: 1,025,489,616 cf Maint.: 0.001 hours (75,917 mh/day) Price:
$250,147,018,656,919
HT: 5 HP: 915,230 [Body].
Space Performance: sAccel (unloaded) 0 G, ( 0 G), sDecel 0 G, sMR 0,
sAccel 0.000 mph/s.
Design Notes:
TL8 robotic super light frame advanced materials (Using greater of
volume or surface area) [Vehicle].
TL8 DR 100 advanced metal [Vehicle].
Payload Cost: $80,000,000
Vehicle Features: computerized controls, 2xduplicate controls, no streamlining.
Body: total compartmentalization.
Volume: 1,025,489,616 cf [Body].
Area: 6,101,530 sf [Body].
Space Performance: Payload 0;
* engine: 420,000,200 lbs
* fuel: 8,400,004 lbs gives Burn Endurance of 8,000 hours
* 50,000,000,000 lbs fuel gives Burn Endurance of 47,619,024.9 hours
= 5,432.33379 years
* Thrust: 300,000 lbs
* LWt: 50,698,137,445 lbs
* Delta-Vee:
21.8 * 1,000,000 * ln (1+(50,000,000,000/698,137,445)) miles/hour in
metres/second = 41,761,573.9 meters / second
2.15 lightyears / (0.5 * 41,761,573.9 meters / second) in years
= 30.8682707 years
* 2 = total trip time of 61 years.
(Still need to increase engine thrust to use up fuel in travel time.)
----->8-----
Thank you for your time,
--
DataPacRat VA3BOS
"You shall not accept any information, unless you verify it for
yourself. I have given you the hearing, the eyesight, and the brain,
and you are responsible for using them." -- Qur'an 17:36.
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