NON Canon thoughts, Ship's Grav in LBB123

[jawillroy]

If I were going to take the bit in my teeth, I'd deepsix standard shipboard contragrav except on tech 13 ships or better, go with fusion torches for m-drives; some sort of lifting body/scramjet requirement for atmospheric flight, and all shipboard gravity courtesy of either constant thrust or rotation. (I'd have to alter damage tables to account for this- losing rotation suddenly would be a big deal)

Passenger service, though comfortable enough underway, would have enough awkwardness at transitions that it would always be considerably more involved than it is OTU. Military ships would save high-gee maneuvers for when they were really needed: you wouldn't see 6G for hours at a time.

Since, though, I'm at the moment dedicated to modelling straight LBB123, none of the above is really indicated.

 

[jawillroy]

If I were going to take the bit in my teeth, I'd deepsix standard shipboard contragrav except on tech 13 ships or better, go with fusion torches for m-drives; some sort of lifting body/scramjet requirement for atmospheric flight, and all shipboard gravity courtesy of either constant thrust or rotation. (I'd have to alter damage tables to account for this- losing rotation suddenly would be a big deal)

Passenger service, though comfortable enough underway, would have enough awkwardness at transitions that it would always be considerably more involved than it is OTU. Military ships would save high-gee maneuvers for when they were really needed: you wouldn't see 6G for hours at a time.

Since, though, I'm at the moment dedicated to modelling straight LBB123, none of the above is really indicated.

 

[Golan2072]

Originally posted by Imperium Festerium:
Since, though, I'm at the moment dedicated to modelling straight LBB123, none of the above is really indicated.

And LBB123 seems to use the following assumptions:

1) ALL LBB2 drives are TL9+, see the TL table in LBB3. TL8- drives would probably require additions to the system.

2) Manouver Drive is a Fusion Torch.

3) Ships have shipboard gravity, but no (?) inertial dampening and hence the 6G limit.

4) The cost of streamlining and/or the hull itself subsumes Air/Raft-style (more accurately Speeder-style, I'd assume - Air/Rafts take LOOOOOOOOONG times to get to orbit) grav-modules that work only in (relatively) close proximity to gravity wells (up to a high enough orbit to safely use your Fusion-Torch-M-Drive, possibly up to the Moon with decreased efficiency) but DO'NT work for longer-range interplanetary drives.

5) The Power Plant is Fusion, probably CNO-catalyzed.

 

[Golan2072]

Originally posted by Imperium Festerium:
Since, though, I'm at the moment dedicated to modelling straight LBB123, none of the above is really indicated.

And LBB123 seems to use the following assumptions:

1) ALL LBB2 drives are TL9+, see the TL table in LBB3. TL8- drives would probably require additions to the system.

2) Manouver Drive is a Fusion Torch.

3) Ships have shipboard gravity, but no (?) inertial dampening and hence the 6G limit.

4) The cost of streamlining and/or the hull itself subsumes Air/Raft-style (more accurately Speeder-style, I'd assume - Air/Rafts take LOOOOOOOOONG times to get to orbit) grav-modules that work only in (relatively) close proximity to gravity wells (up to a high enough orbit to safely use your Fusion-Torch-M-Drive, possibly up to the Moon with decreased efficiency) but DO'NT work for longer-range interplanetary drives.

5) The Power Plant is Fusion, probably CNO-catalyzed.

 

[jawillroy]

I'd say I'm good with 1,2,4 and 5; I'm inclined to think that by the time LBB2 2nd ed was published, inertial damping was considered part of the whole packet: Traders&Gunboats went by LBB 1st ed, and assumed inertial damping even on 1G ships.

 

[jawillroy]

I'd say I'm good with 1,2,4 and 5; I'm inclined to think that by the time LBB2 2nd ed was published, inertial damping was considered part of the whole packet: Traders&Gunboats went by LBB 1st ed, and assumed inertial damping even on 1G ships.

 

[aramis]

I'd want inertial dampening even on 1G ships; helps to prevent "spin sickness" in combat, and at turn-around, etc.

 

[aramis]

I'd want inertial dampening even on 1G ships; helps to prevent "spin sickness" in combat, and at turn-around, etc.

 

[Golan2072]

Originally posted by Imperium Festerium:
I'd say I'm good with 1,2,4 and 5; I'm inclined to think that by the time LBB2 2nd ed was published, inertial damping was considered part of the whole packet: Traders&Gunboats went by LBB 1st ed, and assumed inertial damping even on 1G ships.

Hmmm... And the inertial dampening is limited, i.e. it cannot dampen anything past 6G?

 

[Golan2072]

Originally posted by Imperium Festerium:
I'd say I'm good with 1,2,4 and 5; I'm inclined to think that by the time LBB2 2nd ed was published, inertial damping was considered part of the whole packet: Traders&Gunboats went by LBB 1st ed, and assumed inertial damping even on 1G ships.

Hmmm... And the inertial dampening is limited, i.e. it cannot dampen anything past 6G?

 

[Fritz_Brown]

That seems to be the consensus, 2-4601.

 

[Fritz_Brown]

That seems to be the consensus, 2-4601.

 

[robject]

Originally posted by Employee 2-4601:
Hmmm... What about RAMJETS/SCRAMJETS? How big would be their (hydrocarbon/oxydizer or L-Hyd/LOX) fuel tanks for takeoff+landing for a Size-A world?

(1) Less efficient (or otherwise less desireable) in some ways than an M-drive with a power plant. So, more than 3% per G. Even more than that if you're using High Guard!

(2) Efficient enough to be useful. So, less than 100% of the hull volume per G. I suppose

Strike the balance between (1) and (2) and you have a viable low-tech thrust technology.


Mach 24 is orbital velocity.

Rockets can attain Mach 30.
Assume scramjets can just achieve Mach 24. (Currently it's not clear if they can.)

Assume you've got a hybrid ramjet/scramjet. Use a nuclear ramjet to avoid needing combustion -- and you get a 2 EP powerplant to boot (the equivalent of a Type A power plant, I believe).

You'd probably need 100% hull volume for LOX (used in the upper atmosphere), and another 100% hull volume for regular hydrogen fuel (for simplicity's sake, call it the same stuff Traveller uses).

Make sure your craft has wings: scramjets rely on aerodynamic lift. Your ship will probably be climbing for an hour at hypersonic speeds into orbit. Make sure your craft is well insulated.

Thrust will be low. Scramjet thrust ratio is about 2:1 (rockets are 50:1 to 100:1), and it's already pushing 2 tons of LOX and Hydrogen for every ton of drive. So, to stretch the analogy into fiction, 1 ton of drive could push 1 ton of payload and 2 tons of fuel at 2/3 G.

The engine is larger than a rocket engine, and costs more than a rocket engine plus rocket fuel.

</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">Fission Drive TL7 TL8 TL9
hull% per G 30% 25% 20%

1 EP per 25T
MCr1 per T

ASSUME: craft reenters as a glider (hrs x world size).
Fuel required for one launch:
0.1T per T of drive x world size.</pre>[/QUOTE]Example 1. A TL9 50T craft needs a 10T drive (MCr10) to push it at 1G. To launch from a size A world, the craft needs a 10T fuel tank. Remaining space is then 30T. If the fuel is special stuff (as opposed to just regular Traveller-style fuel), then it will probably cost Cr10,000 to launch this beastie. A bargain for TL7 or TL8, but a rip-off by Imperial standards.

Example 2. A TL7 50T craft needs a 15T drive (MCr15) to push at 1G. To launch from a size A world, the craft needs a 15T fuel tank. Remaining space is then 20T.

Example 3. A TL9 50T craft needs to be designed to reach orbit from a size A world as fast as possible. The limits to technology at TL9 for this drive in this case is 2G, consuming a whopping 20T of space for the engine and 20T for fuel, leaving 10T remaining space.

All of these examples assume the wings are properly designed for the atmosphere they're flying in, by the way.

Plus, I'm sure I'm totally ignoring a zillion physics and/or technical issues.

 

[robject]

Originally posted by Employee 2-4601:
Hmmm... What about RAMJETS/SCRAMJETS? How big would be their (hydrocarbon/oxydizer or L-Hyd/LOX) fuel tanks for takeoff+landing for a Size-A world?

(1) Less efficient (or otherwise less desireable) in some ways than an M-drive with a power plant. So, more than 3% per G. Even more than that if you're using High Guard!

(2) Efficient enough to be useful. So, less than 100% of the hull volume per G. I suppose

Strike the balance between (1) and (2) and you have a viable low-tech thrust technology.


Mach 24 is orbital velocity.

Rockets can attain Mach 30.
Assume scramjets can just achieve Mach 24. (Currently it's not clear if they can.)

Assume you've got a hybrid ramjet/scramjet. Use a nuclear ramjet to avoid needing combustion -- and you get a 2 EP powerplant to boot (the equivalent of a Type A power plant, I believe).

You'd probably need 100% hull volume for LOX (used in the upper atmosphere), and another 100% hull volume for regular hydrogen fuel (for simplicity's sake, call it the same stuff Traveller uses).

Make sure your craft has wings: scramjets rely on aerodynamic lift. Your ship will probably be climbing for an hour at hypersonic speeds into orbit. Make sure your craft is well insulated.

Thrust will be low. Scramjet thrust ratio is about 2:1 (rockets are 50:1 to 100:1), and it's already pushing 2 tons of LOX and Hydrogen for every ton of drive. So, to stretch the analogy into fiction, 1 ton of drive could push 1 ton of payload and 2 tons of fuel at 2/3 G.

The engine is larger than a rocket engine, and costs more than a rocket engine plus rocket fuel.

</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">Fission Drive TL7 TL8 TL9
hull% per G 30% 25% 20%

1 EP per 25T
MCr1 per T

ASSUME: craft reenters as a glider (hrs x world size).
Fuel required for one launch:
0.1T per T of drive x world size.</pre>[/QUOTE]Example 1. A TL9 50T craft needs a 10T drive (MCr10) to push it at 1G. To launch from a size A world, the craft needs a 10T fuel tank. Remaining space is then 30T. If the fuel is special stuff (as opposed to just regular Traveller-style fuel), then it will probably cost Cr10,000 to launch this beastie. A bargain for TL7 or TL8, but a rip-off by Imperial standards.

Example 2. A TL7 50T craft needs a 15T drive (MCr15) to push at 1G. To launch from a size A world, the craft needs a 15T fuel tank. Remaining space is then 20T.

Example 3. A TL9 50T craft needs to be designed to reach orbit from a size A world as fast as possible. The limits to technology at TL9 for this drive in this case is 2G, consuming a whopping 20T of space for the engine and 20T for fuel, leaving 10T remaining space.

All of these examples assume the wings are properly designed for the atmosphere they're flying in, by the way.

Plus, I'm sure I'm totally ignoring a zillion physics and/or technical issues.