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From:	Tzeentch tzeentch666@*********.net
Subject:	-GEARHEAD/SZETO- Laser Weapons and PF to Kilowatts
Date:	Tue, 4 Apr 2000 16:29:48 -0700

Message no. 1 LASER POWER REQUIREMENTS
To determine the power requirements use the following math:

POW= Output in kJ x2 xRate of Fire (use 1 for SA, 3 for BF, 10 for FA)
*POW is rated in kilowatts

For example, the Redline laser pistol (at TL9 I'll assume) is a 400kJ output
weapon so it uses (400 x2 x1=) 800 kilowatts of power per shot.

CONVERTING PFS TO KILOWATTS
Since I have no idea what Mr. Szeto used as the basis for the "Power Factor"
this all a guess. Conversion is made even more difficult by the fact that
baseline items in Rigger 2 (such as electronics) consume no power on their
own. This is highly odd in my mind, but was likely done for simplicty.

I based my conversion on reviewing the power output of Rigger 2 solar cells
(p. 121, Rigger2) as compared to Vehicles 2 solar cells (p. 96, Vehicles2).
R2 solar cells produce .007 PF/second x Body of vehicle compared to
Vehicles2 (TL9) .08kW x square feet.. Since body apparantely also represents
surface area AND mass it makes things difficult.

Conclusions: Based on TL9 solar cells I can assume a Body represents
SOMEWHERE in the area of 10 square feet. I'll go on a limb here and place a
PF as equaling 100 kW/second. That's probably horribly inaccurate of course.
But it does seem to be FAIRLY close to the conversion I outlined above. It
works even better if you assume Shadowrun style solar cells are .07/kW per
square feet (JUST below TL9 cells but better then TL8 which are .04).

Secondary Conculsion: The above laser pistol (based on the Redline
obviously) would thus consume 8 PF/shot. Working backwards you can thus find
how much PF weapons like the Firelance use. Useful information eh?

Ken
---------------------------
There's a war out there, old friend, a world war. And it's not about who's
got the most bullets, it's about who controls the information. What we see
and hear, how we work, what we think, it's all about the information!
Cosmo, 'Sneakers'

From:	Airwisp@*.com Airwisp@*.com
Subject:	-GEARHEAD/SZETO- Laser Weapons and PF to Kilowatts
Date:	Wed, 5 Apr 2000 09:01:59 EDT

Message no. 2 In a message dated 4/4/2000 6:27:43 PM , tzeentch666@*********.net writes:

> LASER POWER REQUIREMENTS

<<<snipped a whole lot>>>

> Ken

Very interesting and well thought out Ken, a question though. Would you want
to put something so technical into a SR text??

>From what I recall from some conversations with Jon Szeto though, a PF is an
abstract amount solely for the purposes of simplifying the mechanics of the
game.

-Mike

From:	Tzeentch tzeentch666@*********.net
Subject:	-GEARHEAD/SZETO- Laser Weapons and PF to Kilowatts
Date:	Wed, 5 Apr 2000 13:40:29 -0700

Message no. 3 From: <Airwisp@***.com>
> In a message dated 4/4/2000 6:27:43 PM , tzeentch666@*********.net writes:
>
> > LASER POWER REQUIREMENTS
>
> <<<snipped a whole lot>>>
>
> > Ken
>
> Very interesting and well thought out Ken, a question though. Would you
want
> to put something so technical into a SR text??

Well. Yes. I don't think the SR system is expandable enough to handle an
overall generic system like GURPS Vehicles or Vehicle Design System. Can you
build a bicycle in Rigger 2? A suborbital shuttle? A simple rocket? Nope.

For what it's intended for it works just fine, don't get me wrong. I'm not
happy with some of the results you can pull out of the system - but that's a
gamemaster issue. I'm hoping the next Rigger will correct the (comparitively
few) problems I have with the design sequence.

> >From what I recall from some conversations with Jon Szeto though, a PF is
an
> abstract amount solely for the purposes of simplifying the mechanics of
the
> game.

That's what I assumed. Not a big fan of numbers pulled out of thin air
though. It makes things more difficult in the long run. After all, at least
with megapulses you can kinda equate it with megabytes of RAM and get
someone realistic results. A Power Factor is...well...uhhh... I don't know!

Ken
---------------------------
There's a war out there, old friend, a world war. And it's not about who's
got the most bullets, it's about who controls the information. What we see
and hear, how we work, what we think, it's all about the information!
Cosmo, 'Sneakers'

From:	Airwisp@*.com Airwisp@*.com
Subject:	-GEARHEAD/SZETO- Laser Weapons and PF to Kilowatts
Date:	Thu, 6 Apr 2000 09:37:28 EDT

Message no. 4 In a message dated 4/5/2000 3:39:01 PM , tzeentch666@*********.net writes:

> Well. Yes. I don't think the SR system is expandable enough to handle an
> overall generic system like GURPS Vehicles or Vehicle Design System. Can
you
> build a bicycle in Rigger 2? A suborbital shuttle? A simple rocket? Nope.

Funny, that is not what you told Keith in IRC the other night.

<grumble>

-Mike

From:	Tzeentch tzeentch666@*********.net
Subject:	-GEARHEAD/SZETO- Laser Weapons and PF to Kilowatts
Date:	Thu, 6 Apr 2000 11:52:51 -0700

Message no. 5 From: <Airwisp@***.com>
> > Well. Yes. I don't think the SR system is expandable enough to handle an
> > overall generic system like GURPS Vehicles or Vehicle Design System.
Can
> you
> > build a bicycle in Rigger 2? A suborbital shuttle? A simple rocket?
Nope.
>
> Funny, that is not what you told Keith in IRC the other night.
>
> <grumble>

It is? Then you must have misread or misunderstood. Perhaps if you add
"..the Rigger 2 system for Shadowrun.." it makes more sense.

What I was referring to is that any space rules don't necessarily need any
zany new vehicle stats, any more then the naval rules REALLY needed
cavitation ratings.

Ken
---------------------------
There's a war out there, old friend, a world war. And it's not about who's
got the most bullets, it's about who controls the information. What we see
and hear, how we work, what we think, it's all about the information!
Cosmo, 'Sneakers'

From:	Tzeentch tzeentch666@*********.net
Subject:	-GEARHEAD/SZETO- Laser Weapons and PF to Kilowatts
Date:	Thu, 6 Apr 2000 13:20:18 -0700

Message no. 6 WALL CURRENT
Here are some more hoops to jump through if this sort of thing interests
you:

You can recharge 2 shots from the Redline laser pistol per hour from an
unnamed power source. I don't thik I'm too far off when I assume this is
plugging the little monster into wall current.

Figuring PFs from Wall Current
Assuming the Redline is 400kJ and requires 800kilowatts of power per shot we
can figure out how much power wall current provides.

It recharges 2 shots per hour. So obviously it must provide 1600 kilowatts
of power over that hour. That's 16 PF if you use my 1 PF0 kilowatts
conversion.

But how much per second? Divide the amount by 3600 and there you go! In this
case you get .4 kilowatts per second (400 joules). Or approxomantely .004
PFs/sec

Other Sources of Data
Guns Guns Guns gives some sample figures both for conventional batteries and
wall power that I found helpful. In this case the amounts given above are on
the REALLY low end for what they have for household current.

G3 suggests (assuming current-tech power grids) 1800 joules/sec from wall
current. That's 6480 kilojoules per hour.

Possible Reasons
SR notes that they use peak-discharge batteries for lasers. Since obviously
the batteries are not directly dumping into the beam we have to assume that
they power an HPG or a set of capacitors. I assume the recharging
limitations are a function of the batteries themselves. But it's somewhat
odd that you can't top off the HPG or capacitors (which vehicles would
probably do) on the Redline or other manpack lasers.

Ken
---------------------------
There's a war out there, old friend, a world war. And it's not about who's
got the most bullets, it's about who controls the information. What we see
and hear, how we work, what we think, it's all about the information!
Cosmo, 'Sneakers'

From:	JonSzeto@*.com JonSzeto@*.com
Subject:	-GEARHEAD/SZETO- Laser Weapons and PF to Kilowatts
Date:	Thu, 6 Apr 2000 19:03:36 EDT

Message no. 7 <thread in general snipped>

Actually, the PF isn't my own creation --- it was one of several
concepts that I carried over from the original Rigger Black Book, for
the sake of maintaining continuity. I have no idea what Philip MacGregor
(the writer of the RBB) had in mind for the PF to represent, nor does
anyone else who currently works at FASA.

As for what a PF represents, here's how I would figure it:

To estimate the performance of a PF, I would benchmark it against a
"core" electric vehicle that appeared in the BBB: the Mitsubishi
Runabout (which appeared in the BBB1 and BBB2).

Looking up the stats of the Runabout on p. 162 of Rigger 2, we find out
the following stats for the Runabout:

Speed: 75 mpt
Body: 3
Fuel: 150 PF
Economy: 0.5 km/PF

Based on the Fuel and Economy, we can figure the operational range of
the Runabout to be 75 km. To keep the math simple, let's assume that the
economy is "highway" and that the Runabout is operating under
"highway"
conditions. (If you want to be specific, say we're running it on a test
track.)

One of the descriptions of energy is the capability to do work. As basic
high school (pre-uni for the non-Americans) physics teaches us (or did
in my day) is that work is defined as the change in the total energy
(potential + kinetic) of a system. In this case, the amount of work
performed by the Runabout's engine is what's needed to bring the
subcompact from full stop to full speed.

The basic formula for the kinetic energy of a body is 1/2*m*v^2. We know
that v is 75 meters per combat turn, which translates into 25 meters per
second (1 combat turn = 3 seconds, so to convert to m/s, you divide the
Speed Rating by 3). Looking on the Body Ratings Table on p. 23 of Rigger
2, we find that Body 3 covers a range of weight from 200 to 750 kg. We
estimate the gross vehicle weight of the Runabout to be somewhere in the
middle, say 500 kg. So the kinetic energy of a Runabout running at its
maximum sustained speed is (0.5)*(500)*(25)^2, or 156,250 joules.

But wait, there's more.

Not only is the electrical engine getting the Runabout from 0 to 75, but
it's also fighting off the natural deceleration caused by various
different factors (friction, air resistance, and so on). In my Honda
Accord, I have noted that when I let the car coast, it decelerates at a
rate of approximately 5 mph in 3 seconds (both in city and highway
driving). That translates to a deceleration rate of:

-5 mph/3 s * 1610 m/mi * 1/3600 s/hr = 0.74537 m/s^2 (rounded to 5 places)

Of course, to counteract this natural deceleration, the engine has to
provide enough force to provide equal forward acceleration. Again,
harking back to basic physics, Force = mass * acceleration, so in this
case, the force needed is:

(500 kg) * (0.74537 m/s^2) = 372.69 newtons

Also, basic physics tells us that another definition of work is force
exerted across a distance. Since we've already figured the operational
range to be 75 km, a simple way to figure work (if we ignore the effect
of the Runabout accelerating to full speed) is

(372.69 newtons) * (75,000 meters) = 27,951,750 joules

So the total work done by that 150 PF engine is 156,250 plus 27,951,750,
or 28,108,000 joules (rounded down to 28 megajoules).

Dividing this by the fuel quantity (150 PF), we come to a rate of 1 PF =
187 kilojoules (rounded off).

OK, granted, this is a very simplistic calculation and ignores a lot of
extenuating factors. (Not to mention the mechanical efficiency of the
drive system.) But it's probably close enough to get you in the
ballpark.

Also, if you tried this same calculation on other sorts of Shadowrun
vehicles, you will probably not get a close result. I suppose that you
could blame it on the fact that, before Rigger 2, there really wasn't a
consistent system for designing vehicles (or if there was, nobody told
the current staff about it.) When I went about developing the
construction system, I ended up benchmarking the various chassis and
power plants against "core" vehicles that appeared in the BBB. Of
course, YMMV.

So, 1 PF = approximately 187 kJ. So what? What does this mean in
layman's terms?

Well, 1 watt-hour of electrical energy is equal to 3600 joules (power =
work/time, so work = power * time, and 1 joule = 1 watt * 1 second). So
187 kJ = about 52 watt-hours. Which is slightly less energy consumed
than a 60-watt light bulb shining for an hour. (Incidentally, the power
units on a Pentium-type PC, so I'm told, are rated at 250-300 watts, so
1 PF would run a PC for about 10-12 minutes.)

In automotive terms, one horsepower is equal to about 745.7 watts, so 1
PF is the same amount of energy consumed by a 4-hp motor running for
about a minute.

Make of that what you will.

-- Jon

From:	Tzeentch tzeentch666@*********.net
Subject:	-GEARHEAD/SZETO- Laser Weapons and PF to Kilowatts
Date:	Thu, 6 Apr 2000 16:35:08 -0700

Message no. 8 From: <JonSzeto@***.com>

> <thread in general snipped>
<snip excellent example>

> So, 1 PF = approximately 187 kJ. So what? What does this mean in
> layman's terms?

I got approxomantely 100 kJ based on the comparisons of the solar cells.
Nice to see its pretty close even looked at from another view.

> Well, 1 watt-hour of electrical energy is equal to 3600 joules (power > work/time,
so work = power * time, and 1 joule = 1 watt * 1 second). So
> 187 kJ = about 52 watt-hours. Which is slightly less energy consumed
> than a 60-watt light bulb shining for an hour. (Incidentally, the power
> units on a Pentium-type PC, so I'm told, are rated at 250-300 watts, so
> 1 PF would run a PC for about 10-12 minutes.)

If we use PF0kJ (rounded up) and assume solar cells in Shadowrun generate
.08kw/square meter (and further assume 1 Body can be extrapolated to 10
square feet) we get 2850. Which is actually slightly more helpful (depending
on what you are doing) for using Vehicles 2nd Edition.

Any chance of a more consistent use of "PFs" in future products Jon? It
would be very helpful for other tasks (determining laser recharge rates,
etc).

> In automotive terms, one horsepower is equal to about 745.7 watts, so 1
> PF is the same amount of energy consumed by a 4-hp motor running for
> about a minute.

1 hp generates about .746 kilowatts (per second obviously!)

> Make of that what you will.

Quite helpful (if just for showing me I was not completely off in my
conversion!). Thank ya!

> -- Jon

Ken
---------------------------
There's a war out there, old friend, a world war. And it's not about who's
got the most bullets, it's about who controls the information. What we see
and hear, how we work, what we think, it's all about the information!
Cosmo, 'Sneakers'

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