MarkH
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M3700
Last edited:
I am getting about Mach 2.7 with in both RASAero and OR.
Good point about instability at high mach. Yeah, I've run enough sims to notice OR limits altitude when stability margin goes negative at high mach. In OR the stability margin drops to a minimum of 0.4 with the tailcone at max velocity, so perhaps I need larger fins, but it isn't affecting altitude since it is still 'stable'. Without the tailcone stability margin only drops to a minmum of 1.5.
I used 2.0 " for nozzle exit diameter.
I think it was the Bare Necessities N5800 thread where they used pretty small fins with a weighted nose , but post flight attributed stability problems to RASAero's optimistic stability calculations
What I'm really after is if I should use the CTI tailcone on a minimum diameter flight, or if I'd get more altitude with a tailcone that has a less steep angle with a base diameter of say 2.6 " , in which case I would turn my own tailcone and affix it to the standard CTI retaining ring.
Really, the reason the CTI 75mm tailcone is so stubby is the 75 mm XL nozzle is pretty short so the TC tapers right to the end of the nozzle. The AT 75 mm single throat nozzle is longer so the AT tailcone is longer with less angle.
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