How does the CCIP gun/rockets mode on the A-10 Warthog calculate range and impact point without a radar?
A Constantly Computed Impact Point (CCIP) related to the Continually Computed Release Point (CCRP) is a calculation provided by a weapon’s sighting system. It is a predicted point of impact found from the launch platform’s movement, the target’s movement, gravity, projectile launch velocity, projectile drag, and other factors that can be entered. It is usually displayed on the Head Up Display (HUD).
‘The pilot enters the target’s elevation into the CCIP system. This is obtained from either looking at the elevation lines on a map (old school) or from a tagging the target with a targeting pod (new school) or from a JTAC (phone a friend).
‘The jet then takes aircraft orientation data, specifically altitude (“Opposite” in the above images) and dive angle (“theta” in the above images), and does some math using “sine” to determine the hypotenuse, or slant range to the target. It also does some math using “tangent” to determine the adjacent, or horizontal distance to the target.
‘Note that determining the length of “opposite” doesn’t really care about the elevation below the jet. It only cares about your elevation relative to the target. Your target can be in a valley and the system doesn’t care if you’re flying over a mountain ridge or the ocean when you send your weapon on its merry way.
‘The system also makes some adjustments based on what it knows about the weapon ballistics (rockets, bombs, The Gun, etc.) and how the weapon will be affected by the aircraft’s speed. There are also some adjustments based on the system’s best guess of what the wind is doing between the jet and the ground, extrapolated from whatever wind the jet is experiencing at the moment.
‘That all combines into a handy visual presentation on the heads-up display (HUD) that helps the pilot put the jet in the right place to get the weapons to their intended receiver. The little pipper in the center of the circle indicates where the weapon is expected to impact if you hit the pickle button at that precise moment, assuming the elevation is correct in the system.’
‘It’s a pretty snazzy system, and has proven quite effective over the years.