Question about Streamlined warships

[Badenov]

So, I was wondering about how streamlining, partial streamlining, and non-streamlining (or streamlined, standard, and distributed configurations) affect operations. There's a lot of confusion there, starting with the main book saying wedge, cone, sphere or cylinder hulls are 'standard' (p106, middle left) where High Guard lists Wedge and Cone as being 'streamlined' (table on top right). In either case, a sphere is Standard, though, and here's my dilemma:

My copy of Mongoose 2008 says:

​

'A standard-configuration ship can also enter a planet’s atmosphere,​

but is reliant on its thrusters to keep it aloft at all times and is​

extremely ungainly. Pilot checks are required for all movement and​

suffer a –2 DM.'​

So, how many rolls are 'all movement'? At least the landing, but what else and at what stages?

Specifically, what roll is required for skimming fuel?

Specific to landing, it says:

Landing at a starport is a Routine (+2) task for​

most ships taking 10–60 seconds (so most pilots will take extra time​

and get a +1 or +2 DM on top of this – see page 50).​

​

That would be a net +0 roll for landing a spherical ship, modified for extra time, but with a target number of 8, you're going to fail sooner or later. What does a failed landing entail? I find no guidance beyond 'Failing a landing roll means that the ship has landed improperly or even crashed' on page 137. Searching for Crashing gets me crashing into space junk and crashing ground vehicles, neither of which seems right, or even never investigates 'landing improperly'.


So how does a spherical-hulled ship (such as the Tigress class) refuel? Only at Highports? Does it chance landing? I suppose if your Tigress pilot flubs their landing roll and you take 2d6 damage, even a 12 is a double-hit, is pretty trivial when you have 2000 Hull. Oh no, 1998 Hull left! This seems pretty trivial given the main book's text on 'standard' configuration:

A standard-hull ship may still enter atmosphere but is very ungainly​

and ponderous, capable only of making a controlled glide to the​

surface. Getting it back into space requires an elaborate launch​

setup and considerable expense.​

That sounds a lot more serious than a -2 to landing! Nowhere describes what the launch setup and expense are. Likewise,

​

A standard-hull ship may have​

scoops for gathering fuel from a gas giant but the process will be​

much more difficult and less efficient. Larger ships of this type​

will often carry a specialized sub-craft (such as a modular cutter,​

see page 135) to perform the actual atmospheric skimming.​

​

But nowhere is the piloting requirements for skimming discussed. I am at a loss.

 

[TamsinP]

There's usually a size limit for landing pads on planets, so anything over that won't normally be fully streamlined; if they will be GG-skimming, they need to be at least partially streamlined. Those will normally be cruisers and large destroyers/escorts which routinely patrol systems away from naval bases.

Capital ships will usually spend most of their time at naval bases, occasionally showing the flag at important systems (High Pop, A or B starport) - in either case they will have access to refueling from the base/starport. On operations, they would be accompanied by gigantic fleet tankers which carry subcraft able to skim from gas giants.

I can't speak to the rules for skimming in MgT1e as I don't have that edition. In MgT2e there are rules for skimming in The Traveller Companion.

 

[whartung]

capable only of making a controlled glide to thesurface.

Controlled glide similar to how a brick glides. It's more a controlled fall, as if it has a parachute. "We're falling, just not as fast as we should be."

A standard-hull ship may have scoops for gathering fuel from a gas giant but the process will be much more difficult and less efficient.

Unless they document how a normal skimming operation goes, "more difficult" and "less efficient" aren't very meaningful.

Larger ships of this type will often carry a specialized sub-craft (such as a modular cutter, see page 135) to perform the actual atmospheric skimming.

Apparently it's "difficult" enough to warrant carrying fuel shuttles and/or relying on tankers. Those are expensive and take crews in contrast to fuel scoops.

The modular cutter is a lousy fuel shuttle.

I think MT has some actual verbiage about the skimming process, I haven't seen it actually written up anywhere else though, not even the original Starship Operators manual. Maybe the Mongoose one actually addresses it.

 

[Badenov]

Controlled glide similar to how a brick glides. It's more a controlled fall, as if it has a parachute. "We're falling, just not as fast as we should be."


Unless they document how a normal skimming operation goes, "more difficult" and "less efficient" aren't very meaningful.

That's my point. I was wondering if there was guidance from any other sources.

Apparently it's "difficult" enough to warrant carrying fuel shuttles and/or relying on tankers. Those are expensive and take crews in contrast to fuel scoops.

The modular cutter is a lousy fuel shuttle.

And pretty impractical when you need to fill a 190,000 ton fuel tank. 30 tons at a time is going to take 2-1/2 years. Not that the Tigress has them. I suppose they retain the capability for emergencies only and normally refuel at a highport? Overall I think any ship that can be easily refueled by a mod cutter is way too small to have cargo space for a mod cutter.

Though now I'm imagining a ship with 50T cargo total that carries a mod cutter as its only cargo. The cutter scoops fuel, refuels the ship, carries cargo to and from the planet while the ship remains in orbit, and the cargo never gets unloaded, it makes the jump in the mod cutter's bay, gets dropped off at the next planet. Cutter drops cargo, picks up fuel or skims, drops fuel in the ship, goes back to planet, picks up new cargo, lather, rinse, repeat in the next system.

You could do it. It's wildly inefficient, but it would work as I understand things.

I think MT has some actual verbiage about the skimming process, I haven't seen it actually written up anywhere else though, not even the original Starship Operators manual. Maybe the Mongoose one actually addresses it.

I would love to know more.

 

[TamsinP]

Though now I'm imagining a ship with 50T cargo total that carries a mod cutter as its only cargo. The cutter scoops fuel, refuels the ship, carries cargo to and from the planet while the ship remains in orbit, and the cargo never gets unloaded, it makes the jump in the mod cutter's bay, gets dropped off at the next planet. Cutter drops cargo, picks up fuel or skims, drops fuel in the ship, goes back to planet, picks up new cargo, lather, rinse, repeat in the next system.

That wouldn't work. Fuel tankage can't be used for cargo and cargo holds can't be used a fuel tanks. You would need two 30-ton modules, one for cargo and one for fuel.

 

[Badenov]

That wouldn't work. Fuel tankage can't be used for cargo and cargo holds can't be used a fuel tanks. You would need two 30-ton modules, one for cargo and one for fuel.

Oh well.

 

[Condottiere]

Dog's breakfast, I think.

The sheer presence of a Tigress in the atmosphere should create turbulence, if only for everyone else, the mass might be enough to ignore everything except a hurricane.

Then you have ground pressure, you might be why water landings are popular, not only for filling up the tanks.

My interpretation of the current rules set is that is calm conditions, anything with a gravitational based manoeuvre drive is that any hull configuration can slowly descend safely, partial and total streamlining allows greater atmospheric manoeuvrability and acceleration, without continuously rolling dice.

 

[mike wightman]

Ice can be cargo...

 

[Badenov]

Ice can be cargo...

Ice can be cargo, but a ton of ice is not a ton of fuel, sadly. A ton of fuel is specifically a ton of liquid hydrogen (Main book, Mongoose, 2008, p 105 gray box, which is where the 1 ton to 14-ish cubic meters conversion comes from). Other forms of fuel can be sucked in, water, H2 gas, but it has to be stored as liquid hydrogen to have the energy density to give you 14 days of powerplant or the power for the jump tonnage. It's never stated, but the conversion to liquid hydrogen has to be part of the scooping process, and why it takes the listed time (1-6 hr). Ironically, while researching this, I discovered the piloting requirement for scooping, (same ref, p 141 top) which requires a standard pilot check, so Spherical would make it at -2.

 

[TamsinP]

Just to note that a tonne of ice at 0C would have a volume of a little over 1 m^3, so 1 dTon would be a little under 14 tonnes of ice. Let's round that to 14 tonnes, of which 2/18 will be Hydrogen, ie 1.555 tonnes (cf 1 tonne of liquid hydrogen per dTon).
However, that ice/water would need to be "cracked" to get the hydrogen for fuel which would take time - fine for power plant use, but not for jump fuel which needs to be delivered very quickly.

 

[McPerth]

That would be a net +0 roll for landing a spherical ship, modified for extra time, but with a target number of 8, you're going to fail sooner or later.

Take more time to do it, as per cautious task (as per Going faster or slower, page 50 MgT1E CB). This added with a good pilot (and some computer support) may make it quite safe, albeit slower than a full streamlined ship...

In MT, good starports were said to be able to assist landings with repulsors, but IIRC MgT has not them...

What does a failed landing entail?

I'd make it failure level dependent, from some minor damage to ship destuction

So how does a spherical-hulled ship (such as the Tigress class) refuel?

That's why they have subcrafts. In the case of the Tigirs, his escort group (and even his fighters, as it doesn't use to go alone) may help in getting fuel from wilderness sources, albeit this may be a little slow (I guess in FFW they would count as non-streamlined and need a full week to refuel)

Just my thoughts, YMMV...

 

[Badenov]

Take more time to do it, as per cautious task (as per Going faster or slower, page 50 MgT1E CB). This added with a good pilot (and some computer support) may make it quite safe, albeit slower than a full streamlined ship...

In MT, good starports were said to be able to assist landings with repulsors, but IIRC MgT has not them...

Concur, taking time will help, but to get the same roll as a streamlined ship, you'd need to extend the 10-60 minute landing evolution to 6-24 hours. Though I guess it makes sense for something huge and ungainly like a Tigress to take that long to land carefully. That actually does work for me.

I'd make it failure level dependent, from some minor damage to ship destuction

Which is a 'You make the call.' What I was hoping for was official guidance. Me making the call almost always ends up being not a good call.

That's why they have subcrafts. In the case of the Tigirs, his escort group (and even his fighters, as it doesn't use to go alone) may help in getting fuel from wilderness sources, albeit this may be a little slow (I guess in FFW they would count as non-streamlined and need a full week to refuel)

Just my thoughts, YMMV...

Alas, the Tigress has no subcraft with cargo capacity, and with a fuel requirement of 190,000 tons, that's going to be super hard to arrange. To take the time to refuel with the same roll as a streamlined ship, it would move the base time up to 10-60 hours.

 

[Condottiere]

That would depend on the composition of the organic aerospace group.

 

[Badenov]

That would depend on the composition of the organic aerospace group.

If you're referring to the Tigress, https://wiki.travellerrpg.com/Tigress_class_Dreadnought presents it with 300 50-ton fighters. But if they were flying fuel tanks, it'd only add up to 1,500 tons of fuel, they'd still need to make 126 runs to fill up the Tigress. I can only conclude that "best known warship within the Third Imperium" (flavor text ref same URL) is best known for being difficult to refuel in actual warfare situations. It's going to be either slow or risky or only used when the owner is quite sure they're going to win the system.

You'd have better luck with a squadron-mate of the Tigress of roughly the same size, scooping once, transferring fuel, and then scooping again for themselves, presuming spacecrafft can conrep like modern wet Navy ships do.

 

[AnotherDilbert]

So how does a spherical-hulled ship (such as the Tigress class) refuel? Only at Highports?

With tankers or skimming.

Does it chance landing?

In Mongoose and T5 partial streamlining is no big deal, they can land, just slower. In earlier editions that was a no-go.



The question is: What is cheaper, a non-streamlined warship with a tanker, or a streamlined warship?
Answer: Warships are streamlined, in order to be strategically mobile.
There are enough systems without gas giants to be a problem. If there are neither gas giants nor oceans, you need tankers or drop tanks.



Simplified:

MgT1 Trillion Credit Squadron, p19:
Refuelling
On a campaign scale, ships either refuel completely during the refuelling phase or take an entire week to complete the operation. Determining how long the refuelling takes depends on both the average configuration of the fleet and source of fuel. Only fleets which are streamlined may refuel at ocean worlds; fleets which are either partially or fully streamlined may refuel at gas giants, and any ships may be refuelled by refuelling facilities such as starports and tankers.
A fleet is considered streamlined if ships with fuel tankage equal to 50% of the total across the fleet have a streamlined configuration, while it is considered partially streamlined if 50% of the fuel tankage is aboard partially streamlined vessels. For an unstreamlined fleet to refuel at a gas giant, at least 10% of its fuel tankage must be aboard ships that are partially or fully streamlined. For a partially streamlined fleet to refuel at an ocean world, at least 10% of its fuel tankage must be aboard ships that are fully streamlined.

So, a Tigress would need an escort or tanker with a total of ~96 kDt fuel capacity to refuel quickly (less than a day?) at an ocean, or ~20 kDt to refuel slowly (approaching a week?).


If a fleet has enough streamlined ships, refuelling is quick and easy.
If a fleet has some streamlined ships, refuelling is slow and cumbersome.
If a fleet has next to no streamlined ships, refuelling is an adventure...

 

[mike wightman]

Ice can be cargo, but a ton of ice is not a ton of fuel, sadly. A ton of fuel is specifically a ton of liquid hydrogen (Main book, Mongoose, 2008, p 105 gray box, which is where the 1 ton to 14-ish cubic meters conversion comes from). Other forms of fuel can be sucked in, water, H2 gas, but it has to be stored as liquid hydrogen to have the energy density to give you 14 days of powerplant or the power for the jump tonnage. It's never stated, but the conversion to liquid hydrogen has to be part of the scooping process, and why it takes the listed time (1-6 hr). Ironically, while researching this, I discovered the piloting requirement for scooping, (same ref, p 141 top) which requires a standard pilot check, so Spherical would make it at -2.

Unrefined fuel can also be obtained by dipping - sucking it up as water, ammonia, methane, etc.
You feed it through your fuel processor into your fuel tanks.
14 cubic metres of ice contains more hydrogen than 14 cubic metres of liquid hydrogen. Since you can use water as unrefined fuel you could just melt the ice into your fuel tanks but risk drive failure and misjump.
14 cubic metres of water is 14,000kg of which 1/9 is hydrogen, or 1,560kg
14 cubic metres of ice is 12,740kg of which 1/9 is hydrogen, or 1,420kg
14 cubic metres of liquid hydrogen is 1,000kg, carrying ice cargo as spare fuel is more efficient than wasting space on collapsible tanks.

 

[TamsinP]

14 cubic metres of ice contains more hydrogen than 14 cubic metres of water.

That's incorrect. Ice has a lower density than water (~910 kg/m3 vs 1000 kg/m3), which is why it floats.

 

[kilemall]

Unrefined fuel can also be obtained by dipping - sucking it up as water, ammonia, methane, etc.
You feed it through your fuel processor into your fuel tanks.
14 cubic metres of ice contains more hydrogen than 14 cubic metres of water. Since you can use water as unrefined fuel you could just melt the ice into your fuel tanks but risk drive failure and misjump.
14 cubic metres of water is 14,000kg of which 1/9 is hydrogen, or 1,560kg
14 cubic metres of liquid hydrogen is 1,000kg, carrying ice cargo as spare fuel is more efficient than wasting space on collapsible tanks.

Ice gets you the trifecta, water, hydrogen fuel, and oxygen. Really that’s all you need for deep space survival except for construction material and a starter set of organic material to grow/manufacture.

 

[mike wightman]

That's incorrect. Ice has a lower density than water (~910 kg/m3 vs 1000 kg/m3), which is why it floats.

I know, I mistyped it was meant to say 14 cubic metres of ice contains more hydrogen than 14 cubic metres of liquid hydrogen which is easy to spot from the rest of the post - corrected now.

 

[Badenov]

Unrefined fuel can also be obtained by dipping - sucking it up as water, ammonia, methane, etc.
You feed it through your fuel processor into your fuel tanks.
14 cubic metres of ice contains more hydrogen than 14 cubic metres of liquid hydrogen. Since you can use water as unrefined fuel you could just melt the ice into your fuel tanks but risk drive failure and misjump.
14 cubic metres of water is 14,000kg of which 1/9 is hydrogen, or 1,560kg
14 cubic metres of ice is 12,740kg of which 1/9 is hydrogen, or 1,420kg
14 cubic metres of liquid hydrogen is 1,000kg, carrying ice cargo as spare fuel is more efficient than wasting space on collapsible tanks.

My understanding had been that you picked up 14 cubic meters of fuel or 1000kg, whichever came first. But now I realize that you could pick up >1Ton per D-ton, as long as you refine it into liquid hydrogen before you jump. Technically, the conversion of water or H2 gas from skimming must be part of the scooping process itself, as it's never mentioned separately but is clearly part of the process. Your handling would suffer during the scooping, possibly egregiously, if the conversion to liquid hydrogen was not essentially instantaneous .

You wouldn't even need 14,000kg of water, just 9,000kg of water would be 1000kg of hydrogen, but even that would put a strain on Thrust 1 ships trying to carry it as water or ice while converting it, the ship would be +8 tons per ton of fuel to carry it that way.