Re: [FT] Weapons Design System Concept - some numbers

In message <5.1.0.14.1.20010611195306.009f9a30@m1.853.telia.com>
	  Oerjan Ohlson <oerjan.ohlson@telia.com> wrote:

> Charles Taylor wrote:
> 
> >Ok, some further thoughtson this:
> >
> >Oerjan's 'total cost' (TC from now on) formula is:
> >
> >TC =
> >Cost of system (MASS x COST/MASS)
> >+ cost of fraction of engines used to push system (0.2 x MASS x 2 for
> >Thrust 4 human engines)
> >+ cost of fraction of FTL drive used for system (0.1 x MASS x 2)
> >+ cost of fraction of hull that holds system + drive fractions ([1 +
0.2
> >+ 0.1] x MASS x 1)
> >
> >where MASS is mass of system, COST/MASS is cost per mass of system.
> 
> Um, no. The engines don't use 30% (ie. 20% + 10%) of the Mass of the 
> *system*; they use 30% of the Mass of the *system + engines*. That's a

> pretty important difference - your "0.2 x MASS" and "0.1 x MASS" in
the 
> engine terms above should in fact be 0.2*1/(1-0.2-0.1)*MASS and 
> 0.1*1/(1-0.2-0.1)*MASS respectively (ie., 0.29*MASS and 0.14*MASS),
and the 
> hull cost is MASS*1/(1-0.2-0.1) = MASS*1.43

D'oh, I though it was going to easy - forgot that bigger engines need to
be even bigger to push themselves :-(
> 
> The full TC formula for an FTL-capable ship is
> 
> (System MASS)*(1 [basic hull] + Cm +
THRUST/20/(1-0.1-THRUST/20)*(Ct+1) + 
> 0.1/(1-0.1-THRUST/20)*(2+1))
> 
> where Cm is COST/MASS, Ct is cost per mass of main drive, and THRUST
is the 
> thrust value of the main drive.
> 
> For a thrust-4 Human-drive FTL-capable ship we get THRUST = 4, Ct = 2,
so 
> the formula becomes
> 
> TC = (System MASS)*(1 + Cm + 4/20/(1-0.1-4/20)*3+0.1/(1-0.1-4/20)*3) =
> 
> = (System MASS)*(1 + Cm + 0.2/0.7*3 + 0.1/0.7*3) =
> 
> = (System MASS)*(Cm + 2.3)
> 
> 
> Similarly for a thrust-4 Kra'Vak ship (Ct = 3) it becomes
> 
> TC = (System MASS)*(Cm + 2.6)
> 
> Now re-calculate all your values based on these updated formulae <g>
>
Well, I tried the new numbers on my 'Archaic Pulse Torp' example - and
the final answer (after rounding) looks the same, however, it has now
been rounded _up_ rather than _down_ slightly.

[snip]
> 
> >3) Add PDS capability.
> >
> >Oerjan values this as +4 to TC for all-arc PDS capability, in which
case
> >the cost of 'PDS as B-1' is +2 1/3 to TC, and the cost of 'PDS as
K-1'
> >is +1 2/3 to TC.
> 
> I'd estimate that 'PDS as B1' (exactly 1/2 of full PDS) is +2 TC,
while 
> 'PDS as K-1' (1/3 of full PDS) is +1.33. (It is an addition to the TC,
not 
> to the cost of the system alone - thus no extra 1/3!)

Hmm.. I calculated 'PDS as B1' as being slighly more than half as
effective as a PDS - I'll check.

Of course, this is for all-arc coverage - any ideas on the TC mod for
3-arc PDS (or PDS as B1) capability? 1-arc? (probably not a lot).
> 
> >Digression - IIRC somewhere it is stated that B-1s and K-1s used as
PDS
> >require an active fire control - but I can't find this in either
Fleet
> >Book!
> 
> That's in MT. I suggest that this rule be ignored though :-/

Makes things simpler.
> 
> [hardening snipped - the figures look similar to what I arrived at
long 
> ago, but I no longer have those files]
> 
> Later,
> 
> Oerjan
> oerjan.ohlson@telia.com
> 

Thanks for the corrections - should have noticed that one.

Charles