Energy production for power plants in 3.1

[captainjack23]

I have to say, I do not follow how the drive design sequence works at this point in the larger context of the game. It designs ships, but they don't seem to be the kind of ships that it implies should be designed.

Issues thus far.

The power values for the plant assume that the m drive of a similar letter takes more power than the plant -The assumption of Aramis that that gives proportional acceleration results is good, but is it intended ? It does make older designs non-compatable from first principle.

If the power is a range, that can be accessed at will, why do we need the lower bound ?

If the max is the overclock value for jump drive, is the effective reliable power produced somewhere between the two ? - shouldn't it be enough to run the M drive, the electronics, and occasionally fire an energy weapon ?

 

[AKAramis]

I have to say, I do not follow how the drive design sequence works at this point in the larger context of the game. It designs ships, but they don't seem to be the kind of ships that it implies should be designed.

Gar has integrated two concepts into the drive system:

1) a power production rate (which is WAY too low, IMO)
2) a reserve power capacity. (AKA, batteries or capacitors)

You've got a steady power per turn.
You have a maximum power available.

If you use less than the standard, you can save it up.

To Jump with matched drives, you're going to need most of that reserve power filled. This is NOT a problem. This is a good idea. (IMO)

The problem is that the power requirements are too high for just about everything else. A fully charged Bk2 design can't fire more than one battery-round using this system.

The problem is 4-fold:

1. power production needs to scale with drive size, at present, it doesn't.
2. weapons and MD draw too much power
3. The nominal ratings appear to be useful for only up to 10 minutes on matched drive designs
4. there are no movement rules yet to know if that's as big an issue as I suspect it to be.

 

[captainjack23]

General comment about Reserve power:
As regards reserve vs constant power, I could sort of see it if the idea was that many military systems on small ships can only be fired by reserve power. However, functions like M drive don't make sense requiring reserve power at normal output/performance.

Cap

 

[captainjack23]

Increasing thrust,power etc.:
Okay, I like the concept, but the rules are hard to follow and too dispersed, and seem to have some unwritten assumptions..

It seems to boil down to this:

An M/Jdrives rating is its MAXIMUM power input. It can operate with less, and can often produce the same thrust.

Each drive has a range of power consumption from the lowest rated drive that can move that hull to its actual rating.

More power can be pumped in making it perform like a higher rated drive; then that rolls are needed for failure and etc.

Part of the problem with the power/Mdrive tables is here - a type A drive has no lower range, as there are no lower letters; the B -E series have a similar diminishing issue: a compressed operating range.


Here is how I'm assuming the procedure works:

Captain requests a given thrust level." Engineering ! Give me M-5 !"

Power is allocated from any combination of available reserve and/or constant energy from the Plant. If there is enough, continue. If not, engineer rolls to increase output. if successful, continue. If not "they canna take na' moore !" and the process stops. The M drive would seem to produce no thrust , or just the max rated thrust (unclear).

If power is available, compare to thrust/cost chart: allocated power cross indexed with tonnage gives actual thrust; then note the M rating for the allocated thrust (NOT the actual ships M or P).


if the noted rating is <= the ships actual rating, all is well. Requested thrust is provided.(if the power/tonnage lookup =0, no thrust produced)


If it is greater, then the engineer must roll to increase the ships actual thrust to the desired thrust; (note that it is assumed that any increase in power allocated should correspond to an increase in thrust -otherwise, why bother with the roll ?)

If the roll succeeds, the ship has the new thrust for next round. If it fails, the M drive produces either no or normal thrust (unclear) and is damaged:
"Ah, wheel, Capn', aye hoop ye' speak Klingonese "

Is this description correct ?

The concept is pretty cool, and It's not a bad system; it does need the rules cleared,consequences/results explicitly spelled out and rules consolidated: the engineer rolls for thrust are in the actions section, the power/tonnage/rating rules are in a table (and are underexplained) and , and the damage effects are in several other places.

Oh yes, an outline would help, too, as in the combat action sequencing rules.

Cap

 

[barasawa]

Redundant power plants is a good idea if you are going to get shot at. That way it takes more hits to totally disable you.

Checking on something I realized a discrepancy. The power plants SUCK!

The bigger they are, the more efficient (output and cost) they should be, but they aren't. As to coming anywhere close to providing the output they need to support their M-Drives, uh, not even close.

Let's look at a 900t ship. If it has an E drive (1g thrust) it needs 9 energy/round to run at that 1g. However, the E Power Plant only provides 3/round. Err?!? So what if I massively outdo the E rating. A P rating only gives 7/round... I have to go to an S class plant to even get 1 flipping grav thrust out of that oversized paperweight!

Hmmm.... Here's an idea. Let's use a series/parallel distributed power system. It also compartmentalizes it, so if one component dies, I'm not dead in space. Ok, let's see.

Type A: 2/round (12 storage) 4t 8Mcr (Uses 1t fuel per week)
Type P: 7/round (90 storage) 43t 112Mcr (Uses 14t fuel per week)

Type Ax10: 20/round (120 storage) 40t 80Mcr (Uses 10t fuel per week)

Well, that's interesting. A type P, which can't even run that drive, is a freaking joke compared to a stack of 10 type A plants. The Type P makes close to a third the power per round and has a third less storage capacity. It weights 3 tons more, costs 32Mcr more (appx 1/3rd more), and uses 40% more fuel!!! The type P is looking like a 3 legged cow at a horse race...
(the appx 30% results comes up a lot, somebody is definitely using a formula based on 3s.)

Aren't the more advanced plants supposed to come out better on these numbers?

Don't get me wrong, I love Traveller and I do understand this is a beta with bugs to be worked out. But I really feel I have to point out this massive discrepancy. After all, if you can't find the problems, you'll never get them fixed. (And IMHO, this is a big issue.)

By the way, power usage numbers for Environmentals (aka life support), sensors, and other incidentals would be nice to know. Especially since they will be a constant drain.

Suggestion. Add the option of capacitor banks. They increase power storage for a cost of Mcr and tonnage.

Thanks. Waiting impatiently for 3.2 (and 4.0, and RC1, etc...)

 

[Mongoose Pete]

1 power production needs to scale with drive size, at present, it doesn't.
2 weapons and MD draw too much power
3 The nominal ratings appear to be useful for only up to 10 minutes on matched drive designs

I agree!

Let's look at a 900t ship. If it has an E drive (1g thrust) it needs 9 energy/round to run at that 1g. However, the E Power Plant only provides 3/round. Err?!? So what if I massively outdo the E rating. A P rating only gives 7/round... I have to go to an S class plant to even get 1 flipping grav thrust out of that oversized paperweight!

This just proves that the current energy outputs are badly broken!

At an absolute minimum, a power plant must generate enough power to run the equivalent rating of M drive. (I have no problems if the ship needs to coast whilst preping for its Jump drive.)

I too, would like to see a rough guideline for the energy costs of things like life support and sensors. When it comes to cruise liners I start to wonder if the life support requirements of hundreds of passengers doesn't start to become significant... and having critical battle damage when a choice needs to be made between life support or M drive can be a high point of an adventure! :twisted:

Suggestion. Add the option of capacitor banks. They increase power storage for a cost of Mcr and tonnage.

This is actually a damn good idea. If stored power was separate from the normal power plant output, then this could fix part of the problem whilst still preserving the idea Gar was trying to present.

If you introduce Capacitor Banks then these could be required by all ships as the energy store used to build up the charge for jump. Non-military ships could also optionally use them to power their weapons.

As a default value off the top of my head, make each capacitor bank store around 10 Power per ton (more or less depending on TL). This would mean a 1 ton capacitor bank could supply the energy for three pulse laser shots, or a type A jump.

Capacitor banks however should be dirt cheap. I.e. a fraction of the cost (and perhaps space) of the next power plant upgrade. This would make them economically attractive to non-military ships. It is also a good way for a ship's crew to improve the combat ability of their vessel without needing to rip out and replace their entire power plant (realistically an untenable procedure) or raise their weekly fuel bill.

Military ships of course should still be greatly overpowered to provide continual surplus energy for their weapons, and give some damage redundancy. However, they too could benefit from an over-engineered capacitor bank (beyond what's needed for jumping), their so called 'emergency reserve power'.

At around 10 Power stored per ton, this still allows the idea to be slotted into the blueprints of a Suliman Scout ship, and shouldn't unbalance ship design. It allows civilian ships the ability to fight a few rounds before their energy reserves give out, but keeps them well below the capability of a war ship. Pirate vessels could simply be civilian ships with massively enlarged capacitor banks, giving them the edge against normal merchants, but not the endurance required to defeat a naval ship.

Of course, these are only throw away values. If power plant outputs are upgraded (as I hope they will be), the storage capacity should be jiggled to keep them in balance.

Thoughts?

 

[crazy_cat]

Thoughts?

I've just been playing with the starship rules this evening (trying to build a Scout long range tender (500 T, jump 2 capable when piggybacking 3x100 T type S ships)) and the power plant was always giving me concern as I tried to get the numbers to balance - I wasn't in this case looking for combat durability, more the sort of redunancy and safety margin you'd want to build in to an exploration/frontier vessel.

I like the capacitor idea a lot - the numbers may need some work, but the concept sounds excellent - the choices between fight or flight, jumping now and abandoning allies to die, or not jumping at all; or M drive or life support ; or speed vs firepower are key to creating a sense of responsibility and consequence in starship combat.

Ships can be built for a purpose then - a yacht may have luxury fittings where a smuggler may have bigger M drives, a corsair may have massive capacitor reserves and a naval gunship or system defence boat may have a massive PP and huge capacitor reserves but be totally reliant on a resupply tender for fuel and for any J travel.

 

[AKAramis]

Just for reference, NASA runs the shuttle on 3 fuel cells rated for long-term total of 21kW with a 15min peak (due to overheating, IIUC) of 36kW

As opposed to 250MW per power point under Bk5... and based upon the conversions for weapons, I suspect abotu 50MW per power point under draft 3.1....

So... given that rate, and the expected draw of 14kW... that's roughly 2kW/person... including the ops gear.

I suspect about 1kW per person should be good enough... so 1 power per full 500 staterooms?

 

[Mongoose Pete]

Hmm, inspired AKAramis's answers for the space shuttle, I decided to research other vehicles to see if I could get some supporting numbers.

First off, I tried the ISS but couldn't find any technical papers which explicitly stated the environmental and life support power costs. All it states is that the ISS runs on about 62 kW.

Next I tried to think of another vehicle which has the nearest thing to a closed life support system. The only thing I could think of was a nuclear submarine. I made an assumption that the H2O cracking energy to produce oxygen would be equivalent to a future regenerative CO2 system; and that the energy required to heat the sub was the equivalent to heating/cooling a ship in space (colder medium but less conductivity).

Then I hit a brick wall, since most navies don't publish specific info on the 'hotel loads' (the life support, sensors, environmental control, cooking, computers, lighting, laundry, etc) of their vessels. Most 'specialists' say that 25% of a sub's energy is spent on the hotel load, so an LA class with a 25MW reactor suposedly assigns about 48.5kW per crew member! Whereas a Vanguard class nuclear sub, which definitely spends 850kW on its hotel load, comes out as 6.3 kW per crew member. Unfortunately I found no consistent value.

Of course these figures include a significant amount dedicated to computers and sensors, so the basic life support value is hidden... but it does indicate the vast amount of energy spent (in military ships) on auxiliary systems other than engines and weapons... which might be a good guideline for Gar if he decides to include power requirements for other ship systems.

If anyone just happens to know the energy production of cruise liners, I'd be interested to know if the military proportions of approximately 75% engines and 25% 'hotel load' is the same in civilian ships?

 

[AKAramis]

Note that I took the shuttle's nominal load and simply divided by nominal crewing, then presumed that it was 50% "household" and 50% flight.

Note also, tho': the shuttle has apparently got about triple occupancy and 2 small craft SR... she's got about 67cumets of hab space... each SCSR is about 28, so that's 56...

Seriously, shes got 5 tons displacement of habspace. (2300cuft, per http://www.shuttlepresskit.com/scom/scom.pdf )

 

[EDG]

Is this a problem in CT? How does CT handle it? If the CT system works and makes sense then why change it here? (I ask since I'm generally clueless about CT ship design nowadays).

 

[Mongoose Pete]

Is this a problem in CT? How does CT handle it? If the CT system works and makes sense then why change it here? (I ask since I'm generally clueless about CT ship design nowadays).

Oh, its not really a problem as such. Its just with the introduction of Power points to run the drives and weapons, it feels a little half done not to include the energy requirements for other auxiliary systems, such as life support and sensors.

The academic discussion of the last few posts is simply to get an idea of how much energy those sub systems require in comparison with drives and weapons. Unfortunately in the real world we only have a few space vehicles or military submarines to model from. But those examples suggest that currently anywhere from 50-75% of a vehicle's generated power is used for moving and weapons. The rest is used by life support, sensors, computer infrastructure, etc.

If we use these as guidelines for energy management on space ships, then it suggests that ship's power plants should produce more than simply what is necessary for the M-Drive. For small ships I suppose the 'hotel loads' are potentially small enough to be ignored. But when you scale up, the life support for a 2,000 person space liner will be extremely high and needs factoring in.

Of course the ship design rules don't necessarily need to include such things, but since it already covers energy requirements for drives and weapons, it seems little effort to complete the job. An extra line stating 'x power is required per y staterooms (or per y cubic meters of habitable space)'; and a column on the sensors table listing the energy cost - just like the weapons. Both minor changes.

The big problem still remains that power plants should be able to supply enough energy points to run the equivalent M-Drive... with a little extra for auxiliary systems.

What I'd personally like to see is the separation of stored power from the power plant to capacitors instead. This would allow for far more flexible ship design (see above) whilst preserving Gar's ideas of how ship combats work. This is a bigger change, but I think it would be very worthwhile.

 

[AKAramis]

Oh, its not really a problem as such. Its just with the introduction of Power points to run the drives and weapons, it feels a little half done not to include the energy requirements for other auxiliary systems, such as life support and sensors.

The academic discussion of the last few posts is simply to get an idea of how much energy those sub systems require in comparison with drives and weapons. Unfortunately in the real world we only have a few space vehicles or military submarines to model from. But those examples suggest that currently anywhere from 50-75% of a vehicle's generated power is used for moving and weapons. The rest is used by life support, sensors, computer infrastructure, etc.

If we use these as guidelines for energy management on space ships, then it suggests that ship's power plants should produce more than simply what is necessary for the M-Drive. For small ships I suppose the 'hotel loads' are potentially small enough to be ignored. But when you scale up, the life support for a 2,000 person space liner will be extremely high and needs factoring in.

Of course the ship design rules don't necessarily need to include such things, but since it already covers energy requirements for drives and weapons, it seems little effort to complete the job. An extra line stating 'x power is required per y staterooms (or per y cubic meters of habitable space)'; and a column on the sensors table listing the energy cost - just like the weapons. Both minor changes.

The big problem still remains that power plants should be able to supply enough energy points to run the equivalent M-Drive... with a little extra for auxiliary systems.

What I'd personally like to see is the separation of stored power from the power plant to capacitors instead. This would allow for far more flexible ship design (see above) whilst preserving Gar's ideas of how ship combats work. This is a bigger change, but I think it would be very worthwhile.

Fundamentally, given the amount of electrical power needed for MDrives, no, we're not going to see anything close to 25%. Even going with 10kW/person, that's still no more than 1 per 50 SR.

Given that, in say, HG, it was 250MW per EP, that put the bulk of ships in the 125MW/ton of plant range. Only the larger liners will need anything.

I also just checked MegaTraveller for its listed requirements for staterooms: 2kW per small SR, 3 per Large SR, 1 per low berth. Pretty low. MegaTraveller also has power plants in the 100-250MW/Td range.

Gravitics (AG and IC) count 70kW/Td of affected space. Life support cranks up another 4kW/Td.

Maneuver drives purn 70MW/ton in MT... it works out to be on par between 1G and the gravitics costs...

But, and this is the warning: it is far easier to simply assume gravitics are part of the maneuver drive.

The niggling details of power ARE a problem.

CT required a PP rated 1 to maintain life support; it was a concenssion to power in an oblique way.

 

[GamerDude]

Ok, Reading the thread and comments regular modern-day power supplies came to mind (20 yrs in USAF as an Electronics Technician).

Power supplies get rated for normal output and a "maximum short duration" output.

The normal output is what it can supply steady under it's maximum rated load.

The maximum rating is what the unit can supply for a very short duration, allowing it to handle a sudden increased demand without burning out.

You do NOT want to be relying on a power source/supply that is running near its maximum output all the time. If you do, you're going to be without power very quickly.

So, as long as the starship creation system is using the same meanings for the ratings, work off your lower of the two numbers and use the higher number as "what's available in an emergency" maximum.

 

[barasawa]

...
Power supplies get rated for normal output and a "maximum short duration" output.

...

So, as long as the starship creation system is using the same meanings for the ratings, work off your lower of the two numbers and use the higher number as "what's available in an emergency" maximum.

Ah, but that's the rub. It isn't. The second number is the amount of reserve power you have stored in batteries, capacaters, etc. Why it is always in multiples of 6 is so you can easily roll d6 to determine how much you have in random encounters. So it's not an amount of per round, it's this many points of use it and it's gone. (If you have 3/round and 14 stored, your drive takes 9/round for the 1G minimum you have only 2 rounds of flight. Your powerplant can't support your drive by itself, and the stored power will only fill the gap for 2 rounds. Assuming absolutely nothing else needs power, you know, like lifesupport, sensors, weapons, etc.)

Hoping Mongoose responds to the issue soon...