The mass of the drop tank would have to be factored into the Jump. If the tank is even only 1 ton, then your ship's mass is 1 ton over. With a 100 ton ship, you would have to do a J-2 just to go 1 parsec.
CT Only: Fuel purification for drop, collapsible, and demountable tanks
- Thread starter snrdg082102
- Start date
The mass of the drop tank would have to be factored into the Jump. If the tank is even only 1 ton, then your ship's mass is 1 ton over. With a 100 ton ship, you would have to do a J-2 just to go 1 parsec.
mike wightman
SOC-14 10K
There are also these possible fates for the dropped tanks:
vaporised by jump flash
drop into jump space rift along with jumping ship, but are destroyed by contact with jump space
vaporised by jump flash
drop into jump space rift along with jumping ship, but are destroyed by contact with jump space
Vladika
SOC-14 1K
If this occurs then the total volume of the tanks are added to the ship volume for jump. A 200dt far trader is now 240dt and has gone from J2 to J1 while those tanks are carried, empty, full, whatever, during jump.
snrdg082102
SOC-14 1K
Hello all,
Spinward Scout's Post 15 from yesterday about where drop tanks are used seems to be partially supported by the drop tank entry on LBB5 page 27 "Such tanks must be replaced each time they are used, so they are practical only on runs to civilized areas, or to increase fuel capacity to allow several jumps." Unfortunately, there is no mention and I can't seem to recall anything about the drop tanks having any capabilities about having any propulsion systems. My take is that the tanks are installed and then filled before the ship leaves the docking port.
Vladika and esampson, my impression between Book 5 and Adventure 5 is that drop tanks are built for a specific hull or hull classes like the Gazelle Close Escort in Supplement 9. Per Book 5 a drop tank costs Cr10,000 + Cr1,000 per ton of fuel carried. Adventure 5 TCS page 14 adds some clarification indicating that Cr10,000 + Cr1,000 per ton of fuel carried is for drop tanks built at the same time as the hull. Adding drop tank capability after construction is done at a cost of Cr1,000 per ton of fuel carried + Cr1,000 per ton of fuel carried. This indicates that they are built for a specific hull or hull class as is the case with the Gazelle Close Escort.
Yep, Supplement Four drop/collapsible/demountable tanks are all ways to store extra fuel which per Book 5 page 27 "increase its range."
Spinward Scout there are two types of demountable tanks. An interior tank that takes up cargo hold space and an exterior tank attached in a similar manner a drop tank per Adventure 5 TCS page 14. My impression is that there is some system in place to retrieve the jettisoned tanks and a high probability that the tanks may have some maneuvering capability. Book 5 appears to indicate that "high traffic systems" are probably where drop tanks are used for commercial vessels. JTAS 4 page 19 indicates that Gazelle Close Escorts routinely retain their drop tanks with a reduction in jump and maneuver as opposed to jettisoning them. According to the article, JTAS 4 pages 14-21, a Gazelle "burns its fuel prior to jump, storing the energy while the tanks are then jettisoned."
All the material relating to drop tanks supports Spinward Scout and Vladika thoughts that retaining them reduces the jump range. Supplement 9 page 17 has the Gazelle capable of J-4/G-4 with tanks retained, jettisoning the tanks J-5/J4, and not having any tanks J-2/M5.
This topic is shaping up to being one of my longest running and my apologies if my latest post missed anyone.
Spinward Scout's Post 15 from yesterday about where drop tanks are used seems to be partially supported by the drop tank entry on LBB5 page 27 "Such tanks must be replaced each time they are used, so they are practical only on runs to civilized areas, or to increase fuel capacity to allow several jumps." Unfortunately, there is no mention and I can't seem to recall anything about the drop tanks having any capabilities about having any propulsion systems. My take is that the tanks are installed and then filled before the ship leaves the docking port.
Vladika and esampson, my impression between Book 5 and Adventure 5 is that drop tanks are built for a specific hull or hull classes like the Gazelle Close Escort in Supplement 9. Per Book 5 a drop tank costs Cr10,000 + Cr1,000 per ton of fuel carried. Adventure 5 TCS page 14 adds some clarification indicating that Cr10,000 + Cr1,000 per ton of fuel carried is for drop tanks built at the same time as the hull. Adding drop tank capability after construction is done at a cost of Cr1,000 per ton of fuel carried + Cr1,000 per ton of fuel carried. This indicates that they are built for a specific hull or hull class as is the case with the Gazelle Close Escort.
Yep, Supplement Four drop/collapsible/demountable tanks are all ways to store extra fuel which per Book 5 page 27 "increase its range."
Spinward Scout there are two types of demountable tanks. An interior tank that takes up cargo hold space and an exterior tank attached in a similar manner a drop tank per Adventure 5 TCS page 14. My impression is that there is some system in place to retrieve the jettisoned tanks and a high probability that the tanks may have some maneuvering capability. Book 5 appears to indicate that "high traffic systems" are probably where drop tanks are used for commercial vessels. JTAS 4 page 19 indicates that Gazelle Close Escorts routinely retain their drop tanks with a reduction in jump and maneuver as opposed to jettisoning them. According to the article, JTAS 4 pages 14-21, a Gazelle "burns its fuel prior to jump, storing the energy while the tanks are then jettisoned."
All the material relating to drop tanks supports Spinward Scout and Vladika thoughts that retaining them reduces the jump range. Supplement 9 page 17 has the Gazelle capable of J-4/G-4 with tanks retained, jettisoning the tanks J-5/J4, and not having any tanks J-2/M5.
This topic is shaping up to being one of my longest running and my apologies if my latest post missed anyone.
Vladika
SOC-14 1K
My take is a bit different.
The actual cost of the drop tank itself is "Cr1,000 per ton of fuel carried" no matter what the size of the tank is.
For new construction the fittings are built at the same time as the ship in question and cost a flat Cr10,000.
To retrofit an existing ship costs considerably more to do the work involved in opening the hull, placing and plumbing the fittings and lines, re-closing the hull, etc. This is what adds the Cr1,000 per ton of fuel to be carried.
In either case the tank itself costs the same. It's just much harder, and expensive, to add to an existing ship.
As for tanks unique to particular ships? Maybe yes and maybe no. I see it could be based on size of tanks as well as possible ship configuration.
I would think though that there would be standard fittings for standard tank sizes, much like navy jet fighters today share a range of drop tanks capable of being fitted to different planes.
snrdg082102
SOC-14 1K
Howdy Vladika,
I just noticed that I left out something on about my take on drop tanks. Book 5, in my opinion, is for designing warships which indicates to me that military hulls are the most probable user of drop tanks and was for new hulls. Which, in my mind (fuzzy as that is), is that the usual practice, as shown by the Gazelle Close Escort Supplement 9, is to have drop tanks constructed for a specific class of ship.
When Adventure 5 came out drop tanks the rule for drop tanks was expanded to allow them to be retrofitted to other hulls after construction.
I just noticed that I left out something on about my take on drop tanks. Book 5, in my opinion, is for designing warships which indicates to me that military hulls are the most probable user of drop tanks and was for new hulls. Which, in my mind (fuzzy as that is), is that the usual practice, as shown by the Gazelle Close Escort Supplement 9, is to have drop tanks constructed for a specific class of ship.
When Adventure 5 came out drop tanks the rule for drop tanks was expanded to allow them to be retrofitted to other hulls after construction.
Book 5 is also for generic Traveller universes. It does not take into account that in the Classic Era, drop tanks is a recent invention that the Imperial Navy is probably still evaluating. The IN designed the Gazelles, which are not supposed to use its drop tanks during normal operations, and it probably have a few other test designs, but that would be all. As far as the Imperial Navy is concerned, drop tanks are probably not a proven concept yet.
On the civilian side, regular use of drop tanks requires much logistical support. It's also possible that it is still under patent to Tukera.
If it hadn't been for the Rebellion, the Third Imperium would have seen a major revolution in interstellar transportation over the next half century (IMO GT:FT should have explored that coming revolution in the GTU).
Hans
Supplement Four
SOC-14 5K
That makes sense...but...
You're saying that the disposable drop tanks use up all the fuel in those tanks and are safely detatched from the ship--all this, in the blink of an eye-- as the ship transitions from normal space to jump space?
The fuel from the jump tank is converted to power and stored in the capacitors for a brief period of time, long enough for the drop tanks to be detached (several blinks of an eye at least
). Then the jump drive is engaged. It was the invention of special capacitors at the beginning of the second half of the 11th Century that allowed drop tanks to be applied to jump drives. The concept of drop tanks itself goes back to pre-spaceflight Terra.Note that these capacitors are a new invention. Once they had been invented, the invention could be applied at TL 9. (i.e. there are no TL restrictions in the HG rules).
Hans
mike wightman
SOC-14 10K
The high capacity accumulators are TL12 and cost MCr0.5, HG1.
This makes sense, and was for some inexplicable reason absent from HG2.
Also the TAS news items are for drop tanks finally being fitted to the civilian fleet in the Spinward Marches, the news item mentions they have been used in the Imperial core for civilian traffic for the last dozen or so years.
We don't have a reference for how long the IN has been using them, but the Gazelle in S9 is a TL14 design, so drop tanks may have been in use by the IN for centuries - we just don't know.
This makes sense, and was for some inexplicable reason absent from HG2.
Also the TAS news items are for drop tanks finally being fitted to the civilian fleet in the Spinward Marches, the news item mentions they have been used in the Imperial core for civilian traffic for the last dozen or so years.
We don't have a reference for how long the IN has been using them, but the Gazelle in S9 is a TL14 design, so drop tanks may have been in use by the IN for centuries - we just don't know.
You won't hear me complain about that, but the fact is that it was omitted from HG2. Just because it was in HG1 doesn't mean it applies. (<cough> jump torpedoes <cough>
). I believe MgT refined the rule a bit, imposing failure chances on lower TL versions.
Which I've taken into account. If it was invented around 1070 it could have been tested first and then put into use in the interior around 1093. Or there could have been a 20 year legal fight to get the IN to declassify the invention.
Based on the canonical numbers for the Gazelle and the Unicorn (CE-13712 and CE-13768) and the canonical date for the building of the Unicorn (laid down 105-1084) I've guesstimated the date for the Gazelle being laid down to 131-1079 (It depends on how many shipyards you decide the construction run was spread around to). The tech level is a slight puzzle, but it can be accounted for. The easiest is that as a test design it was farmed out to TL14 shipyards to avoid tying up valuable TL15 shipyard space. Presumably it was felt that for its purpose it didn't need to be TL15.
Hans
Vladika
SOC-14 1K
Actually, no. I'm not saying it, but Marc W. Miller does say it in numerous Traveller publications, of which I have read and the community at large has debated and debated and is still debating.
snrdg082102
SOC-14 1K
Howdy Ranke,
If Book 5 is not part of the Classic Era then why is the book part of the Classic Traveller collection?
I have been under the impression that everything prior to MegaTraveller was Classic Traveller, even when I made the purchases of the original LLBs back in the late 1970s and 1980s.
Supplement 9 page 17 on the other hand doesn't really indicate, at least in my opinion, if the tanks are routinely retained or jettisoned. However from the following:
While I have GURPS Traveller: Far Trader (GT: FT), sorry but I was called to task in another post for not clearly identifying a source, I haven't dig too deeply, since I keep side tracking myself
to other topics.
Thanks for your continued answers to my questions.
Nuts when I checked the forum I only saw Ranke's which is post 27, when I sent my reply I discovered replies 28 to 33. Luckily, most of what I quoted appears to be a rehash from the six, I hope I counted right, posts.
If Book 5 is not part of the Classic Era then why is the book part of the Classic Traveller collection?
I have been under the impression that everything prior to MegaTraveller was Classic Traveller, even when I made the purchases of the original LLBs back in the late 1970s and 1980s.
I am not sure but I believe that the cover article in JTAS 4 Gazelle Class Close Escort Vessels by Marc W. Miller pages 14-21 came out before Supplement 9 Fighting Ships. The article in JTAS 4 appears to be a mixture of Book 2 design and Book 5 based on the following:
The article in JTAS 4 on page 19 concerning drop tanks has the following entry:
The above section appears to indicate that tanks were not intended to be dropped between jumps.
Supplement 9 page 17 on the other hand doesn't really indicate, at least in my opinion, if the tanks are routinely retained or jettisoned. However from the following:
The case for the tanks being jettisoned/dropped at the time of jump is strongly suggested.
Could I please get the book and page number that indicates drop tank technically is under patent to Tukera please?
There is a good probability that you are right about a revolution in interstellar transportation if MegaTraveller hadn't been introduced.
While I have GURPS Traveller: Far Trader (GT: FT), sorry but I was called to task in another post for not clearly identifying a source, I haven't dig too deeply, since I keep side tracking myself
to other topics. Thanks for your continued answers to my questions.
Nuts when I checked the forum I only saw Ranke's which is post 27, when I sent my reply I discovered replies 28 to 33. Luckily, most of what I quoted appears to be a rehash from the six, I hope I counted right, posts.
mike wightman
SOC-14 10K
JTAS 2, TNS bulletins for the Tukera patent/monopoly on civilian drop tank tech. The same bulletins are re-printed in FFW.
The Gazelle was designed using a much home-brewed version of HG; it appears to use rules that are in HG1 - the drop tanks being included in hull tonnage thus the 4 hard points, the nuclear dampers and the understrength power plant - and HG2 - the 5t PA barbette.
The Gazelle was designed using a much home-brewed version of HG; it appears to use rules that are in HG1 - the drop tanks being included in hull tonnage thus the 4 hard points, the nuclear dampers and the understrength power plant - and HG2 - the 5t PA barbette.
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Supplement Four
SOC-14 5K
The fuel from the jump tank is converted to power and stored in the capacitors for a brief period of time, long enough for the drop tanks to be detached (several blinks of an eye at least
I'll buy that.
Apples and oranges. HG is a rules set, the Classic Era is a setting. You can use any rules set that suits you to run adventures in the Classic Era (I use my house rules); you can use CT rules to run any Traveller setting you like.
That's because they're not supposed to perform J5s unless it's urgently required. So they mostly retain the drop tanks at the cost of only doing J4 or less.
There isn't one. I suggested that as one possible contributing reason why the employment of drop tanks wasn't running rampant by 1105.
Hans
Supplement Four
SOC-14 5K
When you guys refer to "HG2", you're talking about the extensive rewrite of Book 5, yes?
Vladika
SOC-14 1K
HG2 = HG 2nd edition, 1981
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