I've been learning Python as a hobby the last two years. I like spaceflight too. Therefore I wrote this code to simulate the reentry of a Soyuz. I'd appreciate some feedback: https://github.com/fra-mar/soyuz_reentry But what I couldn't find was reliable data about the Soyuz's drag coefficient or the lift to drag ratio. For the Cd I found values ranging from 0.188 to 1.26 and for the L/D 0.38 to 0.5.
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1$\begingroup$ Cd varies with speed, and I assume L/D does as well. $\endgroup$– Russell BorogoveSep 3, 2021 at 17:26
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$\begingroup$ slightly helpful will be @DeclanMurphy's answer to Modelng SpaceX's lift and drag versus angle of attack and Mach number just fyi they are the creator of flightclub.io $\endgroup$– uhohSep 4, 2021 at 0:31
1 Answer
The best estimate I have found online is from a China Academy of Aerospace Aerodynamics paper using CFD. The paper is available on ScienceDirect (free I think?), the $C_D$ & $L/D$ are about 1.3 and 0.25, respectively, at a trimmed angle of attack (Mach = 5).
It should be noted that the focus on the paper is not on obtaining accurate aerodynamic coefficients, but rather looking at their change w.r.t. surface recession (ablation).
Full Reference:
Xu Guowu, Zhou Weijiang, Chen Bingyan, Zhan Huiling, Yang Yunjun, Effect of Recession on the Re-entry Capsule Aerodynamic Characteristic, Procedia Engineering, Volume 99, 2015, Pages 377-383, ISSN 1877-7058, https://doi.org/10.1016/j.proeng.2014.12.550.
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1$\begingroup$ Hi! Yes, it's free. Thank you so much for your answer. $\endgroup$ Jan 2, 2022 at 6:53