Timeline for Dragon ballistic/drag coefficients?
Current License: CC BY-SA 4.0
5 events
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| May 5, 2021 at 13:25 | comment | added | Chris Ison | In my limited experience in this, I've never seen two different CFD models produce the same CD vs Mach curve. This is a gap in the community that I didn't realize existed until a few years ago. First stage flight for F9 is all you really need worry about; second stage starts in near vacuum (>100 kft). Long slender body approximation should work for you given F9's aspect ratio (230:12) even though nose is not sharp on F9. Won't be perfect but quite close for low to medium fidelity trajectory estimates. High fidelity is a different ball game but you are probably not trying for that, I think. | |
| May 4, 2021 at 19:53 | comment | added | user39728 | Thanks! Any good references for cD vs Ma (and maybe even also angle of attack) in ogive rockets similar in shape/size to Falcon 9 (230 ft length, 12 ft dia) and stretching from subsonic through hypersonic regimes? I'm conceding I won't find just the right data, so I'm looking for the best approximation out there... | |
| May 4, 2021 at 19:47 | comment | added | Chris Ison | Check NASA's Technical Report Server (NTRS) for "blunt body aerodynamics". You might find a CD vs Ma curve that can help. Anderson's book on Fundamentals of Aerodynamics has some good materials. | |
| May 4, 2021 at 4:58 | comment | added | user39728 | Thanks, Chris! This is helpful! I'll take a look at Anderson's. Navigation, guidance, control... by themselves they're already so taxing... but once you figure them out, then you're good to go... but sadly, aerodynamics... take a lot of empirical data that is just very hard to find... and nevermind the physics that can seem so elusive just when you thought you had it figured out... Can you say more about how simplified modeling normally is---would you approximate your drag coefficients as constants, say, even though you're covering subsonic through hypersonic regimes? Constants are nice. | |
| May 4, 2021 at 4:43 | history | answered | Chris Ison | CC BY-SA 4.0 |