On Thu, Jun 18, 2020 at 12:49 PM Thomas RUX <xxxxxx@comcast.net> wrote:
Hi kaladorn,

A 300 ton hull with a J5 requires 150 tons of fuel to make a five parsec jump. The hull carries 60 tons of internal jump fuel tankage. One drop tank is installed holding 90 tons of fuel making the fuel total 150 tons. The 90 tons of fuel is used first to begin the charging of the jump when the drop tank is emptied it is jettisoned and the internal tankage finishes the job.

Is there any textual reference to that function? MT's was very limited and unclear as far as I can see. Is there a reference in CT or elsewhere to document the use of drop tanks to fuel a jump?

I'm not clear on how long the build up to a jump is, nor what the stages of that are (MT's SoM might contain some info - I should read it again), but I don't recall any discussion of that in CT anywhere.

Not saying your explanation differs from what I *think* the intent was, but I haven't been able to find the explanatory text that documents that process.

It's unclear (because we have nothing close to science) that explains the conversion of fuel to the energies for a jump drive to operate. Does it all just flash away at once? Doesn't that mean that some of the jump drive would then effectively be built INTO the fuel tankage to support that instant "POOF!".... and where does all that power go? To store it in capacitors in the jump drive would imply the jump drive would have to be I think much larger than it actually is (unless most of the mass is capacitors, but maybe even then). Note the amount of energy that could be generated by that fuel if it went to the power plant. Then look at how big batteries (capacitor is effectively another way of saying 'charge store' just like a battery) and see how heavy they'd have to be and maybe we'd see if the jump drive's are big enough to account for that (Can't use CT as batteries aren't specifically modelled, but other systems do).

If they don't all go 'POOF!' at once, what rate is fuel converted into the drive and how does the drive hold that huge energy density given that the ship's batteries to do that would be I suspect rather massive?

I think they treated J-drives as magic - they move you from A to B without passing through any points between, they magically and perhaps instantly consume a very set amount of fuel (and not the rest in the tank?) and... a miracle happens!

Then later they tried to backsplain the way the process actually worked (to the extent they could do that as many versions of the game may never have done at all... MT: SoM might have made a swing at it, albeit it may not line up with the CT drive fuel consumption etc.).
TomB
Tom Rux
On 06/17/2020 8:31 PM xxxxxx@gmail.com wrote:


I have a query:

In one of the flavours of traveller, I was just reading about external tankage.

That passage described:

- drop tanks - such dry then jump, but no real explanation of where that volume somehow fitted within your ship and it would be much larger than the exiting jump engine so you can't say it just goes there unless it is consumed and a much smaller power storage grid could contain the equivalent amount of energy... in which case why would not every ship have that loaded up with power with their tanks full with another set... so how this works I don't know. I know the historical plane model, but nobody jumped through another reality....

- demountable hard external tanks - should mess with aerodynamics and with mass distributions and vulnerable if you are in hostile conditions, but pretty obvious that this is just 'a bigger gas tank that happens to be stored outside of the hull'. Not sure any concrete detail of the impacts was stated.

- collapsible external tanks - Once you are done with them, collapse them. This could be used to put a fuel bladder in a cargo bay or to carry a soft external tank (even more vulnerable) outside the armour that could be deflated as fuel depleted to the point where it might not be as impaired (compared to an empty demountable hard external tank).

A lot of detail on the particulars, tasks, etc. didn't seem to be in evidence and drop tanks seemed a bit hand-wavy.

Anyone know how the drop tanks are supposed to work in-universe to power jumps where you drop the tanks before activating the jump engine?

Tom


On Wed, Jun 17, 2020 at 2:34 PM shadow at shadowgard.com (via tml list) < xxxxxx@simplelists.com> wrote:
On 15 Jun 2020 at 23:29, Richard Aiken wrote:

> IMTU, I make jump drives for larger volumes progressively less
> efficient. That is, the jump drives get larger and more power-hungry,
> the larger the hull being jump becomes. A 5000 dton hull is as big as
> you can get and still have a jump-capable vessel (after installing
> everything else a ship needs to function).

Silly thought. We know you can make a ship that uses drop tanks for
jump fuel. So how about one where the jump fuel tankage *and power
plant* are external?

Fire up the power plant, run the fuel thru and disconect from the
ship which then jumps.

Put you in a bit of a bind if you get a misjump, but otherwise I
don't see any major problems (assuming it is possible at all).

Be useful for bulk cargo and possibly some military uses. Keeps some
of the more expensive parts of the ship "at home" and usable for
multiple ships.

For two way traffic you'd need one at each end of the jump.

Not sure what to call it. It's sort of an intermediate step between a
normal ship and a jump gate. I think "jump tug" is already taken.

Maybe jump catapult?
--
Leonard Erickson (aka shadow)
shadow at shadowgard dot com


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