HG 2e Solar Panel p. 36 question

[-Daniel-]

Did you raise any of these questions in the playtest? What answers did you get back? Did you feel you received answers that made sense then?

I missed the playtest.

That is too bad. I found the experience quite enjoyable. I learned quite a lot and in a few cases felt I did contribute to the final product. :mrgreen:

 

[AnotherDilbert]

Maybe I'm suggesting that we don't limit future technology to just light. Would you be happier if they were called power panels? Energon collectors? some other form of unobtanium?

As far as I know our current understanding is that most of the energy emitted by the Sun is blackbody radiation (light). We also get some particles with kinetic energy (solar wind) and neutrinos [edit: not neutrons] directly from the core, but containing less energy than the light.

Even total matter conversion wouldn't give all that much more energy than solar panels.

The good news is that there is a lot of light to catch. Objects in orbit, that are weightless, can extend very thin flimsy panels that can be very large, and hence deliver large amounts of power. Since they are flimsy they would be torn apart if you tried to accelerate them or threw some sand at them, but as long as don't do that they should be usable.

So, solar power can be used by satellites, but not for movable ships.

 

[Condottiere]

Jump drives are magic, and can't really be pinned down.

We do have working models of solar panels, and understand the limits, so kinda harder to handwave this technology.

One issue is that basic power requirements are probably too high per tonne.

 

[rust2]

The problem the authors had to solve was long range survey ships needed a lot of fuel every 2 weeks to feed the very thirsty reactors in 1st edition.
The example on pg 42 of 1st ed Highguard has a Survey ship with a Power Plant D. That is 8 tons of fuel every 2 weeks.

Yep, this is where they went into the woods with a completely wrong idea about the fuel requirements of a fusion reactor. Unfortunately this wrong idea became one of the traditions of Traveller, as far as I know only GURPS Traveller uses a reasonable estimate of a fusion reactor's fuel use (= the reactor has sufficient internal fuel to run for its lifetime). And as is often the case, one wrong idea leads to another, here the underestimated fuel efficiency of fusion reactors led to the equally wrong overestimated efficiency of solar panels.

 

[AndrewW]

Yep, this is where they went into the woods with a completely wrong idea about the fuel requirements of a fusion reactor. Unfortunately this wrong idea became one of the traditions of Traveller, as far as I know only GURPS Traveller uses a reasonable estimate of a fusion reactor's fuel use (= the reactor has sufficient internal fuel to run for its lifetime). And as is often the case, one wrong idea leads to another, here the underestimated fuel efficiency of fusion reactors led to the equally wrong overestimated efficiency of solar panels.

Well, we actually had zero power plant fuel at the start, alas this got changed. But at least reduced over the earlier version.

 

[snrdg121408]

Afternoon PDT all,

First thank you all for replying to my question concerning this item of HG 2e Solar Panels p. 36/PDF p. 37 "If the panels are fitted to a ship without a power plant, then assume the (non–existent) power plant is sized to the ship’s basic systems and a Thrust 1 manoeuvre drive."

From your replies and my pondering I'm down to some options:

1. Solar panels acting as a power plant will be sized using the criteria for a power plant capable of providing power to the basic ship's systems and maneuver drive thrust 0 or per the instructions 1. I'm leaning towards thrust 0.

2. Solar panels are use to charge batteries capable of providing power to the basic ship's systems and maneuver drive thrust 0 or per the instructions 1.

3. Forget about using solar panels as described on p. 36 for the non-existent power plant.

Thank you again for the replies.

 

[fusor]

1. Solar panels acting as a power plant will be sized using the criteria for a power plant capable of providing power to the basic ship's systems and maneuver drive thrust 0 or per the instructions 1. I'm leaning towards thrust 0.

2. Solar panels are use to charge batteries capable of providing power to the basic ship's systems and maneuver drive thrust 0 or per the instructions 1.

3. Forget about using solar panels as described on p. 36 for the non-existent power plant.

I'd say Solar panels could practically power systems that required few hundred kw at most, and even then you'd need enormous solar panels (ISS-sized at least). I doubt there'd be enough power leftover to be able to use M-drive at all. They really aren't a practical option unless you really only have the most basic system running at low power - so they might be handy in an emergency (if you can get them unfurled), but that's about it - and if the ship moves beyond the habitable zone then forget it.

Solar panels could be a viable option for small drones and probes though. But not spaceships.

 

[Condottiere]

They're perfect for solar sailing.

 

[fusor]

They're perfect for solar sailing.

https://en.wikipedia.org/wiki/Solar_sail

Solar sails are not quite the same as solar panels (since the latter aren't designed for propulsion and are more sturdy), but solar sails can be used to generate energy as well as propulsion. But they're just as subject to distance and luminosity limitations as solar panels.

 

[Condottiere]

But ours generate an unhealthy amount of energy that can be redirected to the manoeuvre drives.

 

[snrdg121408]

Hello Condottiere

They're perfect for solar sailing.

On HG 2e p. 36/PDF p. 37 in the Drive section are the instruction for solar sails, excellent try;-)

 

[snrdg121408]

Hello again fusor,

Okay, the web gremlins appear to have re-routed my earlier reply to the bit bucket instead of the forum so here goes try two.

1. Solar panels acting as a power plant will be sized using the criteria for a power plant capable of providing power to the basic ship's systems and maneuver drive thrust 0 or per the instructions 1. I'm leaning towards thrust 0.

2. Solar panels are use to charge batteries capable of providing power to the basic ship's systems and maneuver drive thrust 0 or per the instructions 1.

3. Forget about using solar panels as described on p. 36 for the non-existent power plant.

I'd say Solar panels could practically power systems that required few hundred kw at most, and even then you'd need enormous solar panels (ISS-sized at least). I doubt there'd be enough power leftover to be able to use M-drive at all. They really aren't a practical option unless you really only have the most basic system running at low power - so they might be handy in an emergency (if you can get them unfurled), but that's about it - and if the ship moves beyond the habitable zone then forget it.

Solar panels could be a viable option for small drones and probes though. But not spaceships.

I've been looking in HG 2e that indicates how many Power Points equal real world watt, kilowatt, or megawatt which means I'm going by Power Points which is similar to CT LBB 5 HG 2e.

When the PTBs (Powers That Be) provide the conversion I'll revise my options, but I will most likely use solar panels to reduce a power plants' fuel usage by 1/4 extending the on-station time from 4 weeks.

So as not to be going off on the wrong track could someone show me how to calculate the change using the fuel requirement of 2 d-tons for 4 weeks please?

So far my own efforts on this item has not worked out.:-(

 

[Condottiere]

What's acceleration again for actual solar sails, one hundredth gee?

Regardless how you interpret it, solar panellers are the Ferraris of the solar sailors.

 

[fusor]

Regardless how you interpret it, solar panellers are the Ferraris of the solar sailors.

Um, no, they're not. Solar sails are designed to be huge and flexible so they can catch as much sunlight as possible (and btw they're powered by light, not solar wind). Solar panels are just designed to convert light to electricity - they're usually small units, not a single large sheet. You're essentially doing the equivalent of comparing a parachute to a dishcloth.

The wiki article says that a 800x800m solar sail would have a force of 5 Newtons exerted on it by light pressure at earth's distance from the sun. That would result in a pretty tiny acceleration, but it's constant (at that distance) and can potentially be used to propel small objects over a long time.

 

[Condottiere]

While the panels extend beyond the spaceship fuselage, and light would exert some pressure on them, their resemblance to actual unfurling of sails to catch the solar winds is really illusionary, their primary purpose is to capture the energy inherent in light, and convert it to power the onboard manoeuvre drives.

They'd still have to angle and/or tack to optimize exposure of the panels to the light source, but the quicker response to the energy collected would allow them to out accelerate normal solar sailors.

They're sailing vessels, since the external energy collected is diverted directly to the manoeuvre drives.

 

[fusor]

They'd still have to angle and/or tack to optimize exposure of the panels to the light source, but the quicker response to the energy collected would allow them to out accelerate normal solar sailors.

They're sailing vessels, since the external energy collected is diverted directly to the manoeuvre drives.

What "quicker response to the energy collected"? It's exactly the same response. Light is converted to electricity which powers whatever is on the ship. The difference is that solar sails also use the light to move the ship.

Solar sails are like sailing vessels in that they use the light to move (like sails use the wind to move). Whatever "sailing vessels" you're thinking of are apparently capable of converting wind into power for propellers.

 

[wbnc]

One option is that the tonnage indicates the "stowed" size of the solar panels. Assuming you are using a thin film solar cell advanced several Tech levels the array could be folded down and deployed into an array with a much larger surface area.

large rigid panels are what we have to work with at the moment but it is not unreasonable to assume that as progress takes place very thin solar panels could be produced into materials as thin as a sheet of paper or thinner. Current thin film tech is only second generation technology. research into third generation solar cells is already underway.
https://en.wikipedia.org/wiki/Quantum_dot_solar_cell

 

[AnotherDilbert]

One option is that the tonnage indicates the "stowed" size of the solar panels. Assuming you are using a thin film solar cell advanced several Tech levels the array could be folded down and deployed into an array with a much larger surface area.

I think that is a rather safe bet. A 0,5 dT = 7 m3 permanently deployed rigid panel that could withstand acceleration would be tiny compared to our needs and give us a trickle of kW, not the MW we need.

A 100 dT hull needs 20 Power for basic systems, we can get by on half that for basic life support (HG, p16) so minimum 10 Power. If we assume 1 Power is roughly 5 MW*, we need at least 50 MW. At 1 kW/m2 insolation we need 50 000 m2 in the hab zone. A 50 000 m2 sheet that can be packed into a 5 m3 storage space can be a maximum of 0,1 mm thick or about as thick as a piece of paper. That assumes we can fold it perfectly, in reality it would probably have to be considerably thinner. The storage space would also have to contain the framework to suspend the sheet in space.


* Based on MT fusion output at TL2.

 

[wbnc]

One option is that the tonnage indicates the "stowed" size of the solar panels. Assuming you are using a thin film solar cell advanced several Tech levels the array could be folded down and deployed into an array with a much larger surface area.

I think that is a rather safe bet. A 0,5 dT = 7 m3 permanently deployed rigid panel that could withstand acceleration would be tiny compared to our needs and give us a trickle of kW, not the MW we need.

A 100 dT hull needs 20 Power for basic systems, we can get by on half that for basic life support (HG, p16) so minimum 10 Power. If we assume 1 Power is roughly 5 MW*, we need at least 50 MW. At 1 kW/m2 insolation we need 50 000 m2 in the hab zone. A 50 000 m2 sheet that can be packed into a 5 m3 storage space can be a maximum of 0,1 mm thick or about as thick as a piece of paper. That assumes we can fold it perfectly, in reality it would probably have to be considerably thinner. The storage space would also have to contain the framework to suspend the sheet in space.


* Based on MT fusion output at TL2.

yes in deed he space would have to include the framework. So let's see. Why don't we look at an electroactive polymer wire embedded in the fabric of the solar array. the array is stored like a roll of aluminum foil on a spindle..it's fed out and the fibers are energized using a fairly weak charge hat could be stored in a small battery. once the array is spooled out the wires are charged and become rigid. deploying the array. when the crew wants to retract the array hey de-energize the wires and the array folded back into original form and is spooled back up.

the array would be semi-rigid and could possibly withstand very gradual movements o keep the array pointed into the sun, and if the motion of the craft was constant with no serious acceleration or changes in direction the array could be deployed while moving..just not when executing course changes or rapid maneuvers.

a quantum dot solar cell would be about 400-500 Nm thick..if the article I read is accurate... and a sheet of paper is 100,000 nanometers thick... if only 50% of the volume of the array was the nano-cell array that would leave half the volume for the spool, EAP fibers and wiring.

so theoretically it would be possible for a very large array to be compressed down into 1 D-ton volume. Using just technology already being experimented with. At current advancement, it would be ludicrously expensive and difficult to manufacture. I imagine the response to trying something like that until TL-10 or so would be .."can we just build a nuclear plant it's cheaper....."

 

[Condottiere]

If we can wallpaper the solar sails with solar cells, that would be great.

But since I'm looking at this from the Traveller viewpoint, having a panel of solar cells, which resemble a sail, collecting energy and diverting that to the manoeuvre drive, would make a craft so equipped faster than one with an actual solar sail.