Abusing an AHL
- Thread starter Hemdian
- Start date
mike wightman
SOC-14 10K
If a ship can turn under greater than 2G acceleration from its maneuver dive, then its hull should be able to cope with the stresses of landing on a world.
That may be a little on the small side.
For perspective a modern USA CVN Aircraft Carrier has an internal volume of about 100,000 dTon (IIRC my calculations made it 98,000).
--edit--
Always check your notes. 98,000 is the approximate Gross Tonnage(Shipping). Traveller dTon's are divisible by 5. This makes a CVN 20,000 dTon.
--/edit--
If designed for it this would indicate that a craft that size should be able to splashdown at least.
On the other hand an Anatov superlifter (AN-124) has a slightly under 100dTon cargo hold (1270m^3). No total volume listed, but the total is likely to be 2-5 times that size.
DaveShayne
SOC-12
I don't dislike Skimming I just think it's probably not possible in the real world. But your right I don't know why we are having this discusion either.
DaveShayne
SOC-12
In games terms here is one idea.
Chief engineer to the bridge: Sir, while it seems that that such a maneuver (which ever one you want) may be possible I highly recommend that we use our fuel shuttles. A footnote on page 257 of the original blueprints shows that the architect thought it would be possible under a crisis situation if all small craft were lost. The note goes on to warn that the operation should not be attempted unless all other options have been exhausted. In 2000 computer simulations the operation is successful X% of the time.
Let your players decide if they want to take the chance. If the players are not involved then I would not worry about it.
[edit] In YTU pigs can fly if you want. I however would not suggest such a change because it distracts the players.
Tobias
SOC-14 1K
Gas Giant skimming is supposed to take several hours at least. I have this slight suspicion that it isn't about delving into a 20-bar-area and opening the pipes (as an aside: If one would truly delve into a high-pressure area, filling the tanks would naturally be rather beneficial to structural integrity.)
There are proposed techniques for collecting hydrogen in deep space. Now, these wouldn't be sufficient, but in an area with about 0.1 bar of pressure you should have hydrogen in abundance.
Of course, you can now argue "No, Traveller starships dive deep into the Gas Giant, and that is impossible." Very well. I'd rather assume they will use techniques that work rather than consciously try those that don't work just to disprove them.
That is absolutely irrelevant to the question whether it can survive a given set of condition. If the Galileo-launched probe had by some means been lifted out of the Gas Giant when, say, reaching the 10-bar limit, it would have been intact (indeed, the physical integrity probably held out longer than the transmission instruments as well.) Furthermore, it endured pressures more than 100 times higher than a skimming ship would have to.
Regards,
Tobias
David,
How 'deep' into a gas giant atmopshere do you believe a ship has to descend? How fast within that atmopshere do you believe a ship must travel?
Tobias is talking about moving through regions with a pressure of 0.1 bar and no one is suggesting that vessels 'scoop' up liquid hydrogen. It may be liquid in the fuel tanks, but it isn't brought aboard in that state. Some fuel scoop/processing descriptions even mention liquifying by name.
Also, it takes hours to scoop and the vessels doing so are so vulnerable to attack that they require a High Guard. That certainly sounds like they're moving relatively slowly through a low bar region scooping gaseous hydrogen and liquifying it in their fuel tanks to me.
But, hey, YMMV. If you don't like scooping don't use it. It doesn't make my suspenders snap as badly as it does yours.
Have fun,
Bill
How 'deep' into a gas giant atmopshere do you believe a ship has to descend? How fast within that atmopshere do you believe a ship must travel?
Tobias is talking about moving through regions with a pressure of 0.1 bar and no one is suggesting that vessels 'scoop' up liquid hydrogen. It may be liquid in the fuel tanks, but it isn't brought aboard in that state. Some fuel scoop/processing descriptions even mention liquifying by name.
Also, it takes hours to scoop and the vessels doing so are so vulnerable to attack that they require a High Guard. That certainly sounds like they're moving relatively slowly through a low bar region scooping gaseous hydrogen and liquifying it in their fuel tanks to me.
But, hey, YMMV. If you don't like scooping don't use it. It doesn't make my suspenders snap as badly as it does yours.
Have fun,
Bill
Piper,
Skimming can be done via shallow dives in and out of a GG's atmosphere, yes. I think it's how low-maneuver ships have to do it, and it can get you that aerobraking/slingshot effect to boot. Although, if your ship has strong enough lift, it could conceivably hover down into the atmosphere and catch the hydrogen as it rushes by.
Skimming can be done via shallow dives in and out of a GG's atmosphere, yes. I think it's how low-maneuver ships have to do it, and it can get you that aerobraking/slingshot effect to boot. Although, if your ship has strong enough lift, it could conceivably hover down into the atmosphere and catch the hydrogen as it rushes by.
DaveShayne
SOC-12
Let me repeat. I do not dislike fuel scooping in the game. I just think it's unlikely to be possible in real life.
In the context of Traveller's anti-gravity systems it would seem simple to skim a gas giant.
If by "real life" you mean now, well ... it's at least theoretically possible. See this link.
The relevant text is near the bottom of the page and is quoted here:
"Zubrin discusses how such mining might take place in Entering Space. The enabling technology would be a winged craft that Zubrin calls a Nuclear Indigenous Fueled Transatmospheric (NIFT) vehicle. A NIFT would either separate out the helium-3 as it moved through the atmosphere of a gas giant, or else rendezvous in the atmosphere with an aerostat station. It would have the capability of delivering its helium-3 cargo to an orbiting fusion-powered tanker that would, in turn, take it to the inner Solar System."
The book referred to is "Entering Space" by Robert Zubrin. He describes a system of vehicles for skimming Helium 3 from gas giants.
If by "real life" you mean now, well ... it's at least theoretically possible. See this link.
The relevant text is near the bottom of the page and is quoted here:
"Zubrin discusses how such mining might take place in Entering Space. The enabling technology would be a winged craft that Zubrin calls a Nuclear Indigenous Fueled Transatmospheric (NIFT) vehicle. A NIFT would either separate out the helium-3 as it moved through the atmosphere of a gas giant, or else rendezvous in the atmosphere with an aerostat station. It would have the capability of delivering its helium-3 cargo to an orbiting fusion-powered tanker that would, in turn, take it to the inner Solar System."
The book referred to is "Entering Space" by Robert Zubrin. He describes a system of vehicles for skimming Helium 3 from gas giants.
SlightlyLyons
SOC-7
Hey, what about refualing from an airless water planitoid like Europa? Just hover, blast a hole in the Ice with your laser battery, and drop in a hose.
Gnusam Netor
SOC-13
Bleeh!
Why bother skimming on some boring gas giant when you just have to take it from another ship?
and it's refined too!
Why bother skimming on some boring gas giant when you just have to take it from another ship?
and it's refined too!
To add to the argument _for_ hydrogen collection being possible in real-life.
I've seen fuel-skimming Gas Giants as being simlar to an aero-braking maneuver, with the fuel scoop being a ram-jet / Bussard ram scoop type set-up. The scoop would allow air to pass through it, siphoning off the hydrogen and converting it to a liquid form. All of this should be technically possible now (if you just collect all gases to separate later) - you'd have to calculate the aero-braking and additional drag of the fuel scoop in when maintaining escape velocity.
Didn't Voyager 1 use Jupiter's atmosphere as an aero-brake to change course? I think I remember reading something in a book about the JPL at NASA.
"What about refualing from an airless water planitoid like Europa?"
What if Arthur C Clarke is right and the natives object?
I've seen fuel-skimming Gas Giants as being simlar to an aero-braking maneuver, with the fuel scoop being a ram-jet / Bussard ram scoop type set-up. The scoop would allow air to pass through it, siphoning off the hydrogen and converting it to a liquid form. All of this should be technically possible now (if you just collect all gases to separate later) - you'd have to calculate the aero-braking and additional drag of the fuel scoop in when maintaining escape velocity.
Didn't Voyager 1 use Jupiter's atmosphere as an aero-brake to change course? I think I remember reading something in a book about the JPL at NASA.
"What about refualing from an airless water planitoid like Europa?"
What if Arthur C Clarke is right and the natives object?
SlightlyLyons
SOC-7
They didn't mind, they were just photosensitive.
^ I see skimming done by dedicated refueling craft supporting a dedicated tanker. The AHL would rendevous with the tanker, get topped off, then rocket away. The tanker could either follow the AHL to the next system and refuel again, or stay in the nearby system, rebuilding its stock of deuterium/tritium.
This would effectively:
1) keep the AHL from having to enter a deep gravity well and possibly exposing itself to accidental damage or attack just to refuel
2) keep the AHL from having to jump deep into a system and expose itself to detection or attack just to refuel
3) keep the AHL from having to carry a bunch of refueling shuttles or cutters instead of combat craft
4) keep the AHL from having to dedicate space to scoops and refining gear, leaving room for ammo or other supplies necessary for prolonged operation (this could be addressed with additional support craft as well)
This would effectively:
1) keep the AHL from having to enter a deep gravity well and possibly exposing itself to accidental damage or attack just to refuel
2) keep the AHL from having to jump deep into a system and expose itself to detection or attack just to refuel
3) keep the AHL from having to carry a bunch of refueling shuttles or cutters instead of combat craft
4) keep the AHL from having to dedicate space to scoops and refining gear, leaving room for ammo or other supplies necessary for prolonged operation (this could be addressed with additional support craft as well)
