EOIR Missile Stage Properties
Use EOIR stage properties to define the behavior and properties of the exhaust plume. EOIR models the plume as a solid gray body with 99% emittance, utilizing the Planck function and the assigned temperature. You can set the following properties:
| Property | Description |
|---|---|
| On Time Delta | Enter the point in time at which the plume is turned on, specified in seconds from the missile start time. The minimum time is 0 sec and the maximum is 86,400 sec (one day). The value must be less than or equal to Off Time Delta. |
| Off Time Delta | Enter the point in time at which the plume is shut off, specified in seconds from the missile start time. The minimum time is 0 sec and the maximum is 86,400 sec (one day). |
| Temperature | Enter the temperature of the plume, with the minimum being 0 Kelvin and the maximum being 50,000 Kelvin. |
| Relative Width/Length | Enter the relative dimensions of the plume with respect to the lowest stage dimensions. This is a unitless quantity. |
| Flight Type | This field is deprecated. Making a choice has no effect on the calculations. |
Simulating the missile exhaust plume
EOIR simulates the missile exhaust plume in the following manner:
- The shape is attached to the active (lowest attached) stage. The plume shape automatically adjusts its length and width according to the length and width of the first (lowest) shape element on that stage. The shape consists of a sphere and cone, similar to the shape of an ice cream cone, with the sphere attached to the first (lowest) shape element of the stage and the tip of the cone pointing away from the stage.
- You can adjust the autosizing algorithm results by modifying the Relative Width/Length parameters.
- The plume material is internally set to be a very low reflectance Gray Body, highly emissive in the infrared. You cannot override this.
- You can adjust the plume's temperature, and thus its Planck radiance emission, to correlate to the exhaust temperature of some particular missile.
By adjusting the plume's temperature and size, you can model an approximate radiance spectrum and absolute intensity. A larger missile has a larger exhaust plume and therefore greater absolute intensity.
The Time Deltas represent sequential steps in the plume's temporal evolution. The succession of values should be in ascending order. The Time Delta values are expressed in seconds, relative to that stage's active firing.
A sensor scene, imaging a plume, will show the plume turn on or off in the time step following the time indicated by the Time Delta properties.
Real missile plumes change in characteristic (e.g., absolute intensity) over the duration of the burn. You can manually adjust plume characteristics over a time sequence to simulate this effect.