I'm trying to make a two-stage missile. I add one engine and one submunition with zero everything else as a test. Strangely, the range (not Overall Range), despite the first stage carrying no fuel, is 39.3m km, not zero as expected. Changing the separation distance, even to beyond the second stage's maximum range by itself, has no effect on this number.
Now I add another submunition but still no fuel. The first-stage range jumps up to 54.4m km, which puzzles me even more. Again, changing the separation distance does nothing.
Confused, I put one engine, one unit of fuel, and one submunition. The first-stage range shows up as 86.4m km. I add another submunition, and the first-stage range increases to 87.0m km.
There must be some fundamental thing I am not understanding about two-stage missiles. Either that or there's some weird bug going on. My questions:
1. What is going on?
2. When the first stage is in flight, are the engines on the second stage also on?
3. What's a typical process to design a two-stage missile? Like if I want to design box launcher fighters, I first design the missile, then the launcher, then the MFC, fighter, and finally the carrier, so I'd start from the "missile end" and work my way to the "carrier end". Which "end" do I start if I want an effective two-stage missile system?
EDIT: spelling errors.