I said it elsewhere, but I’ve found 0.8 to be a good start for the average aircraft. I’ll crank that up to 1.0 for something that’s a tad more draggy, 1.2 for a monoplane on floats, and 1.4 for something super draggy like the AN-2 on floats. Regardless, 0.4 is too low for anything besides the tiniest fuselage such as on a glider
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