One shot Jump Drives

[Linwood]

The description of one jumps make it clear these are not common for obvious reasons and I'm sure most military ship architects dismissed them a long time ago. Can you imagine 21st century ships using one shot systems to trim the budget?

There have been one-shot vehicles - military and civilian - before, but i’m Very reluctant to carry the analogy very far. A Waco glider in my mind is not analogous to a starship.

One-shots may make sense for lifeboats, especially given the low maintenance costs as baithammer mentioned. I could see them used for colony transports where the intent was to disassemble the ship once it got to the colony world for materials. And maybe they could be used for jump shuttles to help ferry large non-FTL craft (or ships with non-functional jump drives) back for repairs.

 

[phavoc]

There have been one-shot vehicles - military and civilian - before, but i’m Very reluctant to carry the analogy very far. A Waco glider in my mind is not analogous to a starship.

One-shots may make sense for lifeboats, especially given the low maintenance costs as baithammer mentioned. I could see them used for colony transports where the intent was to disassemble the ship once it got to the colony world for materials. And maybe they could be used for jump shuttles to help ferry large non-FTL craft (or ships with non-functional jump drives) back for repairs.

Ah, that's a good point. The gliders used to deposit vehicles and supplies during the Normandy invasion. There were also the German variants used to try and get supplies to North Africa.

For some specific instances they make sense, but as regular pieces of equipment on ships they don't.

 

[Reynard]

Interesting concept. One shot 'gliders' that are meant to make as much use of their tonnage for personnel, equipment and supplies for pre-invasion operations. Maybe give jump stealth and EAG and/or stealth coat so they can exit at the 100D and have the best chance to get by undetected. These would be launched a parsec away hopefully in empty space.

I'm watching 1954 War of the Worlds right now and started imagining the Martian cylinders. And yes, I used Vehicle handbook to recreate a version of the original cylinder, tripods and flying machines as described by an engineer who broke down all the book information.

 

[Condottiere]

I've been tinkering around with the assault glider concept for quite a while now, and a stealthed hull is an expensive feature.

 

[Sigtrygg]

So it should since it breaks the laws of thermodynamics - that doesn't come cheap.

 

[Reynard]

A multi-million credit throwaway engine is very expensive too. Cost depends on what the mission of the craft is trying to achieve. Popping in over a planet and announcing your presence all the way to ground may be bad. Then again, the purpose might not be evading detection as dozens of jump capable landing craft come in screaming hoping enough will survive to continue the objective. One might also try getting the craft overhead and use military drop capsules before attempting to run and possibly making a second jump out system while the primary force jumps in farther back.

 

[baithammer]

It allows riders to maintain a sweet spot between maximum utilization of displacement and the ability to disengage if overmatched or losing the battle in system, while also allowing the tender to leave system after dropping the riders off which removes another vulnerable ship from the system.

As it isn't used all that often it saves a small bit of displacement and a big cost in Mcr.


121,000dt rider w/jump drive Jump-1 > 3,030 dt 4,545 Mcr

121,000dt rider w/oneshot jump drive Jump-1> 2,425 dt 909.375 Mcr

 

[phavoc]

It just seems like some of the new equipment being introduced via the Kickstarter stuff is too good to be true. Very cheap jump drives, sensors that have a detection range of a parsec for jumping ships (1/10 of a parsec to spot basically ANY object, cause a comet can be of any size).

Really makes you wonder if anyone is looking at how these disrupt a number of concepts that are already in place via the core books.

So would you, as a playing group, allow for items like these? What about when you don't have the expansions?

 

[AnotherDilbert]

As it isn't used all that often it saves a small bit of displacement and a big cost in Mcr.

You "forget" the cost of the breakaway hull to be able to replace the one-shot drive without a complete refit:

Should work fine, but the Breakaway Connectors cost more than you save on the OneShot drive:

The One-Shot drive saves ~550 Dt and GCr ~3, but the connectors cost 2000 Dt and GCr 4.

 

[Reynard]

....

 

[baithammer]

As it isn't used all that often it saves a small bit of displacement and a big cost in Mcr.

You "forget" the cost of the breakaway hull to be able to replace the one-shot drive without a complete refit:

Should work fine, but the Breakaway Connectors cost more than you save on the OneShot drive:

The One-Shot drive saves ~550 Dt and GCr ~3, but the connectors cost 2000 Dt and GCr 4.

The breakaway section also avoids having to send the rider to a starport to replace the One-shot drive and can speed up refuel by replace the jump section with a fresh one. (So 1.0 Bcr and 1,450dt is worth it.)

 

[AnotherDilbert]

The breakaway section also avoids having to send the rider to a starport to replace the One-shot drive and can speed up refuel by replace the jump section with a fresh one. (So 1.0 Bcr and 1,450dt is worth it.)

We don't need to switch jump drives if we have a regular drive. If you are suggesting the tender would carry extra jump drive sections, that is just added unnecessary cost.

Refuelling can be done faster and cheaper with UNREP equipment.

 

[baithammer]

The regular drive isn't going to be used often enough to justify the expense and the tenders aren't the ones carrying the replacement drives, that would be depots and logistics ships.

And no UNREP isn't faster as a breakaway hull takes d6 rounds to detach and another d6 rounds to attach the new one, so between 12 - 72 mins with the UNREP having a per hour rate regardless of the size of the system.

 

[AnotherDilbert]

The regular drive isn't going to be used often enough to justify the expense ...

If we can't justify a regular drive, then we can hardly justify the higher cost of a one-shot drive and breakaway hull.

And no UNREP isn't faster as a breakaway hull takes d6 rounds to detach and another d6 rounds to attach the new one, so between 12 - 72 mins with

500 Dt of UNREP equipment can refuel the rider in a single round, much faster and cheaper than using a breakaway hull.

the UNREP having a per hour rate regardless of the size of the system.

No:

Each ton dedicated to the UNREP system allows the transfer of 20 tons of fuel, cargo or ordnance every hour.

 

[Condottiere]

Volume isn't at such a premium that it's the primary factor in the equation.

You still need bunkerage to fuel the transition, so the driving factor has to be cost, and in the specific case of a (star)warship would be the cost of the rest of the components in relation to that of the jump drive and the capability it brings, plus the likelihood of damage.

It's one reason I'm sceptical about the utility of adding stealth to a cheap spacecraft, or an expensive one, unless it's meant to be an infiltration vehicle for a really important mission.

 

[baithammer]

the UNREP having a per hour rate regardless of the size of the system.

No:

Each ton dedicated to the UNREP system allows the transfer of 20 tons of fuel, cargo or ordnance every hour.

Yes.

 

[AnotherDilbert]

the UNREP having a per hour rate regardless of the size of the system.

No:

Each ton dedicated to the UNREP system allows the transfer of 20 tons of fuel, cargo or ordnance every hour.

The size of the UNREP system decides the capacity: if you want to transfer more fuel faster, use a bigger hose.

 

[phavoc]

Volume isn't at such a premium that it's the primary factor in the equation.

You still need bunkerage to fuel the transition, so the driving factor has to be cost, and in the specific case of a (star)warship would be the cost of the rest of the components in relation to that of the jump drive and the capability it brings, plus the likelihood of damage.

It's one reason I'm sceptical about the utility of adding stealth to a cheap spacecraft, or an expensive one, unless it's meant to be an infiltration vehicle for a really important mission.

The thing that drives how fast you can pump fuel is literally the size of the pipes. That is your physical limitation on how fast you can pump liquid hydrogen (well that and your pump, but let's assume you put the right size pump with the right size fuel line). Fuel lines are waste space for a ship, but are still necessary. The space shuttle would receive fuel (liquid hydrogen or oxygen) from it's storage tanks at 1,300 gallon/minute.

1 Dton of space can hold about 14,000 liters, or 3,700 gallons (all numbers rounded). So 10 Dtons of Lhyd is equivalent to about 140,000 liters, or 37,000 gallons. At the listed amount above your fuel would need to pump at (1hour = 60 minute) at a measly 615 gallons/minute or 2,333 liters/minute. Your throughput could be pressurized more, though Lhyd is already under pressure, and the question would be could your pipes take the additional pressure or would they spring a leak? That's something to consider if you are in a hurry to refuel.

UNREP would be based on two separate numbers - liquid and solid transfer. You aren't running a hose down a corridor through airlocks for fuel - fuel is transferred via a hose. Solid transfer of items is going to be based on taking containers of hard goods between ships. And that's going to be transferred via pallets. It's basically two pallets per dton, or 40 pallets. Larger ships will have cargo airlocks designed to accept larger 2-3dton sized containers. Smaller ships will transfer via a pallet, or worst, crates moved individually. The USN has gotten this down to literally a science. Everything is pre-positioned on the supply vessel and then quickly transferred to the receiving vessel. The idea is to time the transfer of bulk goods with the fuel. Depending on the supply ship they may, or may not get munitions. Though underway munitions replenishment is not something that is done that much these days since we aren't at war, and cruise missiles and such are both expensive and they are usually in VLS launchers, which these days are only replenished back in port.

Just last month a Tico-class CG collided with it's supply ship. Operations in space should be much safer since no waves, though it's still possible to have an oopsie.

https://navaltoday.com/2019/02/06/us-navy-cruiser-dry-cargo-ship-collide-during-replenishment-at-sea-maneuver/