01-30-2010, 10:14 PM | #1 |
Join Date: Jun 2008
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(Spaceships) Help me stat drive
If anyone has read the Aliens Universe: Colonial Marines Technical Manual, the dropships engines had three phases starting out as a turbo jet, then scram jet once it reached top jet speed, and then the intakes closed and it became a chemical rocket. How would I stat out this drive for orbital velocities?
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01-31-2010, 04:48 AM | #2 |
Join Date: Nov 2008
Location: Germany
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Re: (Spaceships) Help me stat drive
I haven't read the Manual, which has been OOP for quite some time, but then Aliens isn't exactly unknown ...
However, I have several answers:
Regards, Onno |
01-31-2010, 10:01 AM | #3 |
Join Date: Sep 2008
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Re: (Spaceships) Help me stat drive
From your description, it sounds like it starts as a high-thrust air-breathing engine, changes to a medium-thrust air-breathing engine, then when atmosphere runs out becomes a low-thrust fuel-burning engine. You could approximate this by using reconfigurable systems, where the three systems are a high-thrust (2x thrust, 1/2 delta-V - or in this case, 1/2 time) Jet Engine, a regular Jet Engine, and a low-thrust (1/2 thrust, 2x delta-V) HEDM Engine. Note the high- and low-thrust options for these drives are not RAW but rather extrapolated from the rules of other drives. For simplicity, we'll allow the Jet Engine to use HEDM fuel as though it were jet fuel (we're dealing with ^ anyway). The total cost of each such engine would be, for an SM +8 craft, 69M (3M for HEDM, 10M for each Jet configuration; x3 for 3 possible configurations). Each engine would give 4G on take-off (burning through 1 fuel tank per half hour), 2G on atmospheric flight (going through 1 fuel tank per hour), and 1G thereafter (with delta-V 0.45 per tank).
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Quos deus vult perdere, prius dementat. Latin: Those whom a god wishes to destroy, he first drives mad. |
01-31-2010, 09:32 PM | #4 | |
Join Date: Jun 2008
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Re: (Spaceships) Help me stat drive
Quote:
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02-01-2010, 09:30 PM | #5 | |
Join Date: Sep 2008
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Re: (Spaceships) Help me stat drive
Quote:
Humorously, it should be noted that the turbojet is actually an older, less-efficient design than the scramjet used for the second "stage." I suspect they opted for a turbojet scheme because it sounds like something crazy powerful. They are more powerful (albeit less-efficient) than the turbofans that have apparently replaced them, however, so when you want to lift off a hostile world in a hurry turbojets are probably a good way to go.
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Quos deus vult perdere, prius dementat. Latin: Those whom a god wishes to destroy, he first drives mad. |
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