Posted by: bean
« on: December 20, 2012, 07:53:02 PM »I might have missed the part where you mentioned that it assumed an infinite multiplier.I assumed there was no limit on how much you could vary the multiplier (up to infinity or down to 0, if necessary). It was necessary to make that approximation, but the model fails for short-range missiles.
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In general I don't like to over-engineering my missile designs and therefore I usually end up trying to hit both a range and speed at the same time.Part of the problem is the granularity of the model. The engine size increment is .1, so any optimization has to be approximate. Basically, the point of the model is that if the amount of fuel that you have on the missile is more than about a third of the size of the engine, you're better off cutting the fuel and making the engine bigger with a lower power multiplier. Conversely, if the fuel is smaller than that, and you're not at your maximum power, decreasing engine size and increasing power multiplier is the way to go. If you're pinned by the power multiplier, then the model becomes less helpful.
So, even if I could build a missile with a Speed X and get a range Y, that range might just be more than I need even if I get most out of the amount of fuel I put into that space on the missile. I might rather put some more armour or bigger yield on the warhead and reduce the range to a "good enough" range. No need to have a 400m km range missile if 200m km does it equally well.
When designing MIRV missiles I generally go for the efficiency but on regular missiles it almost never come in to play.