Nuri-rocket and its variation trajectory analysis w/ Aerospace SIM

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Aerodynamics Series

  I had modeled Nuri rocket (KSLV-II) developed by KARI; middle class lift rocket uses 4x75t class for its 1st, 1x75t for 2nd and 1x7t for 3rd stage. Fortunately, many useful information is already in public, so I can reduce my effort to fit the size of Rocket. 

Most of the effort are sizing the dump/propellant weight of each stage and orbit specification. 

Specification from Wiki, weight, motor, payload, and total weight of 2nd stage is known. 

(but propellant mass of 2018 flight, about 14t, is probably not the full loaded mass)

In origin, I targeted 7.9km/s or similar for given altitude for the launch vehicle however, my initial approach gave far-behind launch condition in Aerospace-SIM. So I should increase V_total. 

There are weight (structure, propellant) specification - assumed

Baseline trajectory result from AerospaceSIM, my in-house code, it shows assumed model reach slightly less LEO condition. It is interesting that most of energy from 3rd stage goes to horizontal acceleration. 

Ligher payload (1.5t) make Nuri go to 600km orbit; it requires more time for climb. 

Small launch vehicle that only has 2nd and 3rd stage with 300kg payload; 52t rocket could deliver this payload to 300km orbit with Mach 18. I think burn-time should be tweaked for better acceleration profile. 

SUMMARY

Modeled (with some assumed value) Nuri rocket (KSLV-II) could reach similar profile known to public. 

Upper staged rocket could deliver 300kg payload for LEO (~300km)