Missile Properties

Ballistic Propagator

The Ballistic Propagator defines an elliptical path that begins and ends at the Earth's surface. Specifying a fixed flight time, initial velocity or altitude can further refine the shape of the trajectory.

To define the ballistic propagator:

  1. Select the Ballistic propagator on the Trajectory page.
  2. If necessary, change the Start Time, Stop Time & Step Size. Use the current scenario time period by turning on Use Scenario Analysis Period.
  3. Select and define the ballistic propagator elements.
Elements Description
Launch Location (first 3 fields) Select Geodetic or Geocentric Elements:
  • Latitude (Geodetic), Longitude, Altitude
  • Latitude (Geocentric), Longitude, Radius
If you switch between Geodetic and Geocentric elements, values for Latitude and Altitude/Radius update automatically. (Longitude does not differ along Geocentric/Geodetic lines.)
Flight Parameters (4th field) When you enter a value for one of these elements, the system automatically calculates the other values. Flight parameters can be specified in one of three ways:
  • Fixed Delta-V - The instantaneous thrust to be applied to the vehicle being launched. If you enter 0, the minimum Delta-V is computed for launch and impact locations.
  • Fixed Delta-V Min Ecc - The instantaneous thrust, with minimum eccentricity, to be applied to the vehicle being launched. This option generally results in shallower trajectories and may be a better choice when launch/impact points are close or when they are both on one side of the descent/accent arc.
  • Fixed Apogee Alt - The vehicle's maximum altitude.
  • Fixed Time of Flight - The duration of the vehicle's flight.
Only Fixed Delta-V is available if you use Azimuth and Elevation to specify Impact Location (see below)
Impact Location (last 3 fields) The same combinations of elements are available here as for Launch Location (above). It is not necessary to use the same type of elements (Geodetic or Geocentric) for Launch and Burnout Location.

In addition, you can specify impact location using Azimuth and Elevation angles.

You can also enter launch points by clicking the mouse in the 2D Graphics window, and then clicking OK or Apply on the Trajectory page.