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The DF-21D Antiship Ballistic Missile

The DF-21D Antiship Ballistic Missile

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The DF-21D Antiship Ballistic Missile

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  1. The DF-21D AntishipBallisticMissile Ralph Savelsberg Netherlands Defence Academy

  2. Introduction PRC is developing an Antiship Ballistic Missile against U.S. aircraft carriers

  3. Introduction ASBM has a maneuverable re-entry vehicle (MaRV) MaRV has on-board radar and control fins to steer towards its target

  4. Introduction MaRVs are not a new concept U.S. Pershing II Chinese DF-15B Photo: user rocbolt on

  5. Original DF-21 is two-stage nuclear-tipped missile DF-21A has lighter structure and longer range DF-21C has a conventional warhead DF-21D is ASBM Introduction The ASBM is a variant of the DF-21

  6. Introduction Few concrete details are available in open sources Questions: • How large is missile range (U.S. DoD 1500 km +)? • How far can MaRV deviate from ballistic trajectory? • What profiles can the MaRV fly? Computer simulations are used to find the answers For unknown parameters, use data from • earlier versions of DF-21 • Pershing II • conservative estimates

  7. Introduction Trajectory simulation is split into two parts Ballistic trajectory model MaRV trajectory model

  8. Ballistic trajectory simulations Ballistic trajectory model • Point mass model • Model similar to GUI_missile_flyout by G.E. Forden* • Equations solved in Simulink® *GUI Missile Flyout: A General Program for Simulating Ballistic Missiles, Science and Global Security, Vol. 15, 2007.

  9. Ballistic trajectory simulations Some specifications of the DF-21 and DF-21A have been published Parameters needed to model DF-21 were derived by G.E. Forden* Source: Jane’s strategic weapons systems *A Preliminary Analysis of the Chinese ASAT Test, Tech. rep., MIT, 2007

  10. Ballistic trajectory simulations DF-21A parameters are derived from Forden’s DF-21 parameters • Same propellant • Same burn time • Propellant is 87% of stage mass vs. 85% • Increased mass and mass saved by lighter structure used to lengthen 2nd stage

  11. Ballistic trajectory simulations Simulated ranges agree well with published values The derived missile parameters are reasonably accurate DF-21A booster parameters are used for DF-21D

  12. MaRV mass is estimated using Pershing II data • Mass of Pershing II MaRV is 677 kg, including nuclear warhead • Approx. mass of DF-21D MaRV is 1000 kg, including 500 kg conv. Warhead With this mass, DF-21D range is 1.8•103 km

  13. Ballistic trajectory simulations Visualization in Google Earth™

  14. Ballistic trajectory simulations Total flight time is 12 minutes At start of re-entry speed is 3.7 km/s (Ma=13) at an angle of 39.7o below horizontal

  15. MaRV trajectory simulations MaRV trajectory model • 2D polar coordinates • Includes lift and drag • Equations of motion are those by Hankey* • Equations solved in Simulink® *Re-entry Aerodynamics, AIAA Education Series, AIAA, Washington DC, 1988.

  16. MaRV trajectory simulations The model includes more of the vehicle aerodynamics • Vehicle is steered by changing angle-of-attack a • Model uses quasi-static approach (vehicle is treated as though it is trimmed in pitch) • CL and CD as function of Ma and a are calculated using USAF missile DATCOM code However, this requires knowing the shape and location of center of gravity

  17. MaRV trajectory simulations Shape of the DF-21D MaRV is unknown DF-15B MaRV is too small

  18. MaRV trajectory simulations DF-21D is modeled as Pershing II with 500 kg warhead

  19. MaRV trajectory simulations Maximum angle of attack depends on Ma

  20. MaRV trajectory simulations From 50 km to target, missile is steered using proportional navigation • Commanded acceleration: with N = 3 • Time delay of 0.5 s between commanded and actual acceleration nM • Actual acceleration is limited by alimit

  21. MaRV trajectory simulations Intercept of opening target During 12 minute flight time, carrier can move roughly 12 km (at 30 knots). This is not enough

  22. MaRV trajectory simulations Lateral acceleration is less than the maneuvering limit

  23. MaRV trajectory simulations The MaRV is sufficiently maneuverable to hit targets at 30+ km

  24. MaRV trajectory simulations At the extreme end of the range, it flies almost horizontally

  25. MaRV trajectory simulations A closing target at 20 km is approached from directly overhead This is inside the blind spot of radars on the ship

  26. MaRV trajectory simulations Lateral acceleration peaks at -50 g This is close to maneuvering limit for surface-to-air missiles

  27. Size of sensor cone limits area that can be covered

  28. Conclusions Conclusions • The range of the ballistic part of the trajectory is 1.8•103 km • The aircraft carrier cannot evade • The MaRV can fly trajectories that make it extremely hard to intercept