Supersonic_Zero Drag

[Lukáš Smilek]

Hey!

I am trying to use Suave to simulate small VTOL UAV with hybrid rocket/ramjet propulsion. Following the tutorials and digging in to the source code I was able to come up with a script that runs. But I am not at all confident of a result. Especially drag. 

For example I take a point from mission profile given by altitude and mach:

ρ = 0.385 kg/m^3

V = 300 m/s

projected area via OpenVSP is A = 0.159494 m^2 and SUAVE estimates subsonic drag to Cd = 0.05, supersonic then to 0.15

using these values and D=0.5*ρ*V^2*CD​×A should give about 415N

but suave tells me about 5500N what does not feels correct.

Why can that be? Any thoughts? Thank you!

Best regards,

Lukas