HG 2e Solar Panel p. 36 question

[snrdg121408]

Hello all,

I am trying to confirm my understanding of solar panels extending a power plants duration and being a ship's power plant.: "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."

The basic ship systems on a TL-12 100 d-ton requires 100 x 0.2 = 20 Power and the 1 Thrust point maneuver drive 100 x 0.1 x 1 = 10 Power. The power plant has a power output of 20 + 10 = 30.

A TL-12 Fusion Power Plant of 2 d-tons produces a power output of 30. Per the solar panel rules, p. 36, the solar panel(s) would have a tonnage of 2 x 0.1 = 0.2 which is below the minimum of 0.5 d-tons resulting in a solar panel of 0.5 d-tons. Without the solar panels 1 d-ton of fuel operates the power plant for 4 weeks. With the solar panels the 1 d-tons of fuel allows the ship to remain on station for 8 weeks.

Does the 0.5 d-ton of solar panels provide the same power as the power plant as I believe the direction on p. 36 indicate?

 

[Condottiere]

I rather doubt that solar panels the tenth of the size of a fusion reactor can create the same energy output.

In theory, they should provide enough to run basic ship systems, possibly acceleration factor one.

For a while.

 

[AnotherDilbert]

No power plant fuel is consumed, and endurance is considered infinite, if the ship is not manoeuvring or refining fuel.

HG, p36

The solar panels can power basic systems only.

A ship equipped with solar panels consumes power plant fuel at one–quarter the normal rate so long as it is only engaged in minimal manoeuvring and does not fire any weapons.

If you want more power you have to start the power plant. As long as you are stationary you can run the power plant at reduced power, so using less fuel.

 

[Condottiere]

How much text was copied over without considering the implications?

Solar panels should give out an exact measurable amount of power.

 

[snrdg121408]

Hello Condottiere,

I rather doubt that solar panels the tenth of the size of a fusion reactor can create the same energy output.

In theory, they should provide enough to run basic ship systems, possibly acceleration factor one.

For a while.

Thank-you for your reply, unfortunately that still leaves me with the question of what "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." means and how to incorporate this into a design.

A candle just lit about what the above direction is meaning which is that the solar panels volume is equal to the non-existent power plants tonnage?

Nope, after looking at the details of the CT JTAS 1 Annic Nova and the Annic Nova on p. 144 I'm still not getting the meaning of the direction.

The Annic Nova on p. 144 does appear to be missing the 40 ton pinnaces that act as the ship's Maneuver Drive.

 

[fusor]

There should also be a table like I presented in the "TL 14 Collectors" thread showing the efficiency of the solar panels with distance:

                                          Distance/AU     
Luminosity     0.05     0.25     0.5     1        2     3       4        5     10
1000         40000000  1600000  400000  100000  25000  11111  6250     4000   1000     early B V & giant stars
100          4000000   160000   40000   10000   2500   1111   625      400    100      late B V & giant stars
10           400000    16000    4000    1000    250    111.1  62.5     40     10       mid/early A V
5            200000    8000     2000    500     125    55.56  31.25    20     5        late A V
2            80000     3200     800     200     50     22.22  12.5     8      2        early F V
1.5          60000     2400     600     150     37.5   16.67  9.375    6      1.5      mid F V
1.25         50000     2000     500     125     31.25  13.89  7.813    5      1.25     late F V
1            40000     1600     400     100     25     11.11  6.25     4      1        early G V
0.75         30000     1200     300     75      18.75  8.333  4.688    3      0.75     mid G V
0.5          20000     800      200     50      12.5   5.556  3.125    2      0.5      late G V
0.25         10000     400      100     25      6.25   2.778  1.563    1      0.25     early K V 
0.1          4000      160      40      10      2.5    1.111  0.625    0.4    0.1      mid K V
0.01         400       16       4       1       0.25   0.111  0.0625   0.04   0.01     early M V
0.001        40        1.6      0.4     0.1     0.025  0.011  0.00625  0.004  0.001    late M V

The "100" at the intersection of Luminosity 1 Sol and Distance 1 AU means that the solar panels are "100% effective" there. This just means "they get 100% of the base amount of energy here". The other numbers is the percentage of that energy that they get at that distance around that star. So at 2 AU distance from a 1 Luminosity star, the panels are 25% effective. At 0.5 AU from a 1.5 luminosity star, the panels have an effectiveness of 600%.

So if the panels made 10 power points at 1 AU from a 1 luminosity star, they'd make 2.5 power points at 2 AU distance from a 1 Luminosity star, and 60 power points at 0.5 AU from a 1.5 luminosity star.

 

[Condottiere]

I had fun with using it to create a TIE fighter, but the rules should specifically state how much output a solar panel has, and from that you'd be able to figure out how much you can divert to the drives. Or sensors

Or weapon systems.

Also, distance from light source.

 

[fusor]

And by the way, to generate 1 MW of power using solar panels at earth's distance from the sun, you'd need about 5,000-10,000 square metres of solar panel. The ISS has 2500 sq.m of solar panels, and can generate about 0.1 MW. So if you're talking about generating megawatts of power using solar panels you will either need vast areas of them, or super-efficient panels.

 

[AnotherDilbert]

If we go by MT fusion plants, 1 Power ≈ 5 MW.

Total Solar Irradiation in Earth orbit seems to be about 1.3 kW/m2. If we assume the solar panels give 1 kW/m2 (it's stellar tech) it would take 1000 m2 for 1 MW and 5000 m2 for 5 MW ≈ 1 Power.

A Scout requires 60 Power or about 300 MW. The solar panels able to provide that would be 5000 × 60 ≈ 300000 m2, or for the metrically challenged 42 football pitches (football, not american rugby).

If the panel was even 1 cm thick the panel would be 300000 × 0,01 = 3000 m3 or 214 dT. There is no way that such a panel would withstand 1G acceleration.

And as fusor points out the needed size would increase by the square of the distance from the star, so that if you double the distance you quadruple the needed size of the panel.

Basically there is no way you could power a ship with solar panels.

 

[fusor]

Basically there is no way you could power a ship with solar panels.

Yep. A tiny spaceprobe (which often barely requires above 1000 W) or low-tech space station is one thing (though RTGs would work just as well there), but a traveller-style ship using solar panels? Even magical 100% efficient ones? No way.

I think this (and the other issues found elsewhere) goes to show that this book was written by people who have little or no understanding of even the real-world technologies and principles involved where those are applicable (seriously, how can anyone think that solar panels could offset the power output of a nuclear fusion plant?).

 

[Spartan159]

How much of that energy in orbit is being deflected by earth's magnetic field? How much power does the sun produce outside the magnetosphere? Could high tech be using some particle we have yet to discover?

 

[fusor]

How much of that energy in orbit is being deflected by earth's magnetic field? How much power does the sun produce outside the magnetosphere? Could high tech be using some particle we have yet to discover?

Solar panels are powered by light. Photons. I think you're confusing that with the solar wind, which is deflected by the earth's magnetic field (but is not what powers solar panels).

 

[Spartan159]

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?

 

[PsiTraveller]

The idea is nice, save fuel, run quiet and efficient. It is another example of a good idea in concept that gets hit with folks asking real world physics questions.

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. (pg 107 Core book 1st edition). So if a survey ship could not skim fuel, and lacked a Modular cutter with a fuel module, how did they do long surveys? So they came up with a 10 percent of tonnage rule and bingo, problem solved. Another calculation for a designer player to make and customize their ship.

Then the hard science folks start asking those awkward reality questions.

 

[fusor]

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?

Those are in there already - they're Collectors, and we've already had a massive thread about those.

Problem is, they (like what you're suggesting) are entirely magical, as in there's no physical basis for them whatsoever. I think there's enough 'magical' stuff in Traveller without taking existing realworld concepts and throwing physics out of the window for those too.

Even if you assume 100% efficiency (the current record is around 50%), you still need vast areas of solar panels to get even 1 MW of power, and the power you get drops drastically with distance. They're fine on the MW scale if you want acres of solar panels covering the plains of Mercury, but for Traveller-type spaceships? Sorry, but they're not remotely practical there.

 

[fusor]

Then the hard science folks start asking those awkward reality questions.

Well somebody has to, at some stage of the process! It seems that either they were asked and answered during the playtest process and were ignored, or they weren't asked in the first place. Neither of those are very promising :/ .

 

[-Daniel-]

Then the hard science folks start asking those awkward reality questions.

Well somebody has to, at some stage of the process! It seems that either they were asked and answered during the playtest process and were ignored, or they weren't asked in the first place. Neither of those are very promising :/ .

I must admit, while I agree some questions should have been asked and answered, I would have rather those been asked in the playtest rather than people waiting until a book is released to then begin to ask the questions.

 

[fusor]

I must admit, while I agree some questions should have been asked and answered, I would have rather those been asked in the playtest rather than people waiting until a book is released to then begin to ask the questions.

Which makes me wonder even more about the effectiveness of the playtest. Was everyone asleep at the wheel?

 

[-Daniel-]

I must admit, while I agree some questions should have been asked and answered, I would have rather those been asked in the playtest rather than people waiting until a book is released to then begin to ask the questions.

Which makes me wonder even more about the effectiveness of the playtest. Was everyone asleep at the wheel?

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 saw a lot of questions raised and a lot were debated long and hard. Some may not have been answered in the final document, but it was not for a lack of folks willing to discuss the issues.

 

[fusor]

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. Plus I'm not a fan of public playtests anyway (even though apparently that's what I'm doing now, on a book that's been officially released :/ . Though at this stage it's even less likely that anyone cares sufficiently to fix things).

I saw a lot of questions raised and a lot were debated long and hard. Some may not have been answered in the final document, but it was not for a lack of folks willing to discuss the issues.

I've said this elsewhere, but given how many errors and omissions and ambiguities have slipped through to the "final" product, some part of the process clearly failed.