Jump-4 X-boat Tenders

[Starviking]

It's always puzzled me that X-boat Tenders have essentially been limited to local operation by their Jump 1 capability. If an X-boat needs recovered in an isolated system on the X-boat route then it would seem that recovery would need to be made by a vessel other than the Tender.

It occurs to me, however, that if you open the hangar doors of the Tender, you change it from a 1000 Ton ship to a 400 Ton ship, as the hangar is no longer enclosed by the hull. By the basic MegaTraveller and TNE Rules this means that the X-boat tender is now theoretically capable of Jump 4.

Can anyone think of a solid reason why a Tender, with the required design features + software, couldn't just open the hangar doors, program in a J-4 Jump, and safely complete the Jump?

 

[far-trader]

I long ago built it that way So, it works for me. I'm sure there is some argument to be made against the idea but I won't.

I also allowed use of drop tanks, and fuel in the hanger, to increase recovery range. Of course it's the Type S Scout/Couriers (generally the Detached Duty service) that has to find the wayward X-Boat first. Not that it happens very often.

The lightbulb went on pretty early in my Traveller Naval Architecture career when I wondered "How the heck does one get a J1 X-Boat tender to all those far-flung out of the way and sometimes only high jump accessible systems in the first place?!"

 

[DonM]

I don't understand (perhaps I'm slow?), but how does opening the hangar doors change the volume of space occupied by the tender?

 

[Matt123]

"How the heck does one get a J1 X-Boat tender to all those far-flung out of the way and sometimes only high jump accessible systems in the first place?!"

I figured it just used collapsible fuel tanks in its 600 ton cargo bay, giving it up to 750 tons of fuel total. Thats a range of up to 6 parsecs (allowing for PP fuel).

 

[navanod]

Hmm...what about the jump grid on the hull? It would have to have a grid on the inside of the bay as well, lest everyone get jump-sickness and die.

 

[Icosahedron]

I'm with DonM, opening the doors won't change the size of the Jump Bubble. If this trick worked, somebody would figure a way to put 'doors' on a battleship...

I think size should not be the only factor in the performance of a drive - a truck engine is bigger than a race car engine, but if you rip the bodyshell off a truck, it won't win Formula One.

The rules are a simplification of the reality. In the right context, equating size to performance is a rule of thumb, but if you start twisting the context it no longer holds. I think if a drive is designed for Jump-1, it should remain Jump-1, no matter how much hull you strip off.

I even believe the same should hold for M-Drives. I hate the idea of an unburdened tug boat outperforming a fighter...
Trouble is, I'm fighting physics with that one.

 

[Starviking]

I'm with DonM, opening the doors won't change the size of the Jump Bubble. If this trick worked, somebody would figure a way to put 'doors' on a battleship...

It should change the size of the jump bubble though - else sphere config ships could have smaller jump drives than ships of differing configuration but the same displacement.

 

[Starviking]

I don't understand (perhaps I'm slow?), but how does opening the hangar doors change the volume of space occupied by the tender?

The way I see it - the ship no longer encloses (displaces) 1000 Tons - the 600 Ton hangar bay is exposed to space, the remaining enclosed volume is 400 Tons.

 

[Starviking]

Hmm...what about the jump grid on the hull? It would have to have a grid on the inside of the bay as well, lest everyone get jump-sickness and die.

You'd certainly need that in CT and MegaTraveller.

 

[mike wightman]

No different to the lab ship with the doors open, just instead of a big round ring you have a big rectangular ring.
If the lab ship can jump with loads of empty space 'inside' its hull then the tender should be able to do the same.

 

[rancke]

Tenders are designed to tend, not to go into empty space and fetch lost X-boats. It's stranger that they have jump drives at all, seeing as they're designed to stay in one place for most of their careers. I can only imagine that it's some sort of 'belt and suspenders' notion (or perhaps a fat bribe by a manufacturer of J1 drives ) and that any tender that needs to be placed 4 parsecs away will be taken there by a 10,000T freighter.


Hans

 

[BytePro]

I'm with Icosahedron, see a Jump drive as limited to a max normal operating range that it was designed for - the volume relationship being mostly a meta-game design mechanic.

Same seems reasonable for gravitic M-Drives - as it doesn't matter what mass the drive is hauling around. (Not necessarily true for reaction or other types of drives).

(Though, when it comes to M-Drives, I personally like the idea of an unburdened tug boat outperforming a fighter )

 

[McPerth]

The way I see it - the ship no longer encloses (displaces) 1000 Tons - the 600 Ton hangar bay is exposed to space, the remaining enclosed volume is 400 Tons.

So you're talking about a totally different design, a 400 dton ship able to 'attach' the Xboats to its hull (or at least that's what I deduce from wat you say).

It could work, and could recovery the Xboats and serve them as base, but if they need some mainenance, I think it's better a closed hangar.

I think size should not be the only factor in the performance of a drive - a truck engine is bigger than a race car engine, but if you rip the bodyshell off a truck, it won't win Formula One.

The rules are a simplification of the reality. In the right context, equating size to performance is a rule of thumb, but if you start twisting the context it no longer holds. I think if a drive is designed for Jump-1, it should remain Jump-1, no matter how much hull you strip off.

I even believe the same should hold for M-Drives. I hate the idea of an unburdened tug boat outperforming a fighter...
Trouble is, I'm fighting physics with that one.

IIRC (I can not check it right now, so I'll write from memory) there's a precedent against this affirmation : the Gazelle Close Escort (a controversial design to begin with, I know). With the drop tanks attached, it's treated as 400 dton and has J4 M4. Without them it's treated as 300 dton and has J5 (fuel only for J2) and M5.

Also seems to be somewhat a consensus (as far as I have seen until now) about the fact that carring drop tanks raises you tonnage and lowers your performance accordingly.

You can argue this can only be applied when you raise your tonnage and performance drops (in your former example, overburdening the formula one will lower its performance), but not for raising your performance by lowering the tonnage (stripping the truck won't make it too faster), but the Gazelle example seems to show otherwise. IMO, it had to be designed as a 400 dton ship (otherwise it couldn't have 4 hardpoints), so it should have been designed as J4 M4, and it's by lowering its tonnage (by making part of the fuel tanks removable) that it increases its performance.

 

[Rigel Stardin]

One thing you guys seem to forget in this thread. By removing or opening the cargo bay, this ship is still designed around J1 engine. All you've done is allow the tender to make multiple jumps at J1. Manuvering is a different story....

 

[Starviking]

So you're talking about a totally different design, a 400 dton ship able to 'attach' the Xboats to its hull (or at least that's what I deduce from wat you say).

Not at all - the X-boat Tender's hangar is 600 dT, so if you open it fully to space the ship only displaces 400 dT.

 

[Starviking]

One thing you guys seem to forget in this thread. By removing or opening the cargo bay, this ship is still designed around J1 engine. All you've done is allow the tender to make multiple jumps at J1. Manuvering is a different story....

The way I read it, in Traveller Jump capability is based solely upon the tech level of the Jump Drive. Thus if you have a Tech-15 drive sized for J-1, if you can reduce the displacement of the ship then it should be (theoretically) capable of longer jumps.

 

[Rigel Stardin]

The way I read it, in Traveller Jump capability is based solely upon the tech level of the Jump Drive. Thus if you have a Tech-15 drive sized for J-1, if you can reduce the displacement of the ship then it should be (theoretically) capable of longer jumps.

As an upgrade verison, I get that. But isn't the tender built around a J1 drive? Therefore everything is calibrated for the Jump Drive. Cargo capacity, fuel has been tweak into it. An empty ship, car, or frieght train can go farther because they are not pushing or pulling the max weight they have been designed for. It doesn't need as much fuel to move it. In principle I agree with everything in this thread.

The only problem for this mytical x-boat tender, once it's made the J6 to retrive the wayward X-boat is getting back since it burned up all it's fuel getting there...

 

[BytePro]

Ah - and to think - all those silly Subsidized Merchants - all this time they could have been doing J-2 and 3Gs with a small computer upgrade... all they needed to do was open their cargo bay doors!*

Heck - use a ton for upgrade to Model 2bis and ditch the 20 dton launch and they could make J-3 with plenty of PP fuel left over! (Or use the launch's 13 tons cargo for fuel - with only 3 tons for PP, though one could lose a stateroom/lowberths, etc. to squeeze in more...)

The problem with metagaming the rules in this way is that it 'breaks' the existing designs in terms of what was possible, yet wasn't done.

Not to say exceptions can't be made - Mark's Annic Nova is a prime example of that.

*Converting the 400 dton to 200 dtons with C rated drives. The 50 tons of fuel would only get them J-2, and the computer needs upgrading to 1bis (no extra tonnage).

 

[Matt123]

The High Guard rules allow you to design a dispersed structure hull that you can add ships or components to that would meet your needs.

The "open the bay doors" idea falls apart on numerous levels for all other ship hulls, which are designed as X shape. (X = pick a valid hull type). Remove part of that shape and the performance of the hull under stress will suffer.

Using the same logic, if I create a vacuum in an closed cargo bay/fuel tank/empty stateroom, I also reduce my displacement tonnage. Clearly something is wrong with this idea...

But a similar effect can be achieved several ways. Modular ships & ship components is one. Modular cargo holds is yet another. Most modular systems are built on Dispersed structure hulls.

Other options are the use of drop tanks and external demountable fuel tanks which by extension could be external demountable cargo holds.

But opening the cargo bay doors, your air lock and creating vacuums in non-essential areas of your ship, will not decrease the volume your ship displaces as determined by your hull.

With clam-shell style doors wide open, you have actually increased your volume...

 

[Starviking]

As an upgrade verison, I get that. But isn't the tender built around a J1 drive? Therefore everything is calibrated for the Jump Drive. Cargo capacity, fuel has been tweak into it. An empty ship, car, or frieght train can go farther because they are not pushing or pulling the max weight they have been designed for. It doesn't need as much fuel to move it. In principle I agree with everything in this thread.

The only problem for this mytical x-boat tender, once it's made the J6 to retrive the wayward X-boat is getting back since it burned up all it's fuel getting there...

But as I said, if the ship's displacement can be lowered then longer jumps are possible. For a J-1 drive sized for a 1000 dT vessel, J-2 is possible at 667 dT, J-3 at 500 dT, and J-4 at 400 dT.

So the ship could theoretically make a J-4 jump to recover an X-boat, refuel, then make a J-3 and J-1 jump back to base.

Deep space recoveries would require a jump to the nearest system first - then smaller jumps out to and back with the X-boat.