Following Anderson (University of Utah)'s textbook Modern Compressible Flow:
Following these figures, we obtain that attached shock, which is beneficial from a drag point of view, is present for deflection angles under some θ_max, which is the peak of each successive curve (one per Mach number) in the lower figure. For Mach 1, we approximate this angle as 6°. Thus, we adapt the model as follows:
Following these equations from NASA's Glenn Research Center, we obtained the ideal Mach angle for our rocket based on its velocity. For a velocity of Mach 1.7, we approximate the Mach angle (μ) as 36°. Because the sweep angle is the angle between the leading edge of the fin and a line perpendicular to the longitudinal axis of the rocket, these calculations tell us that the sweep angle (ϕ) should be greater than 54° to reduce drag and interference.
