The “Crank” consists in a turn towards friendly lines (or, if not applicable, towards the safest area) for an angle wide enough to place the target at the gimbal limits of the radar (both azimuth and/or elevation) and without breaking the lock. It is executed right after a missile launch and the objective is reducing the closure rate and therefore the ability of the target to fight back.
This is a Tacview image from my analysis of the steam in Growling Sidewinder’s server. The manoeuvre is very clear:
This example shows very well how this simple manoeuvre achieves the goal.
Imagine to prolong the vectors of the F-14 and the Target. They form a shape similar to a right triangle. The line drawn by Tacview represents the hypotenuse and the vectors of the aircraft the catheti. Since the hypotenuse is always shorter than the sum of the catheti (Triangle inequality), following such vectors means that we are flying a longer path, therefore it will take more time to “meet” the target. This also means that the target now is in an unfavourable position: our aspect is not optimal (flanking) and we are slowing down and therefore the closure rate is drastically decreasing. Moreover, if the targets turns in our direction it will expose himself even more to the AIM-54 roaring in his direction.
The best defence is always denying the hostile the possibility of shooting.
Although in this case the human pilot never changed his course (probably due to poor SA), in a dynamic engagement, the RIO may have to adjust the heading of the F-14 multiple times, if necessary.
Examples of cranking and multiple manoeuvres can be found in the aforementioned Steam in GS’ server.
Recently we were practicing BVR engagement and, although I did not always commanded a crank post launch, you can see multiple manoeuvres in the following Stream (crank example at 58:20):
Effect of Cranking on the radar cone
As the range increases, the trajectory of the AIM-54 changes from flat to lofted. As we know from the WCS Guidance study, if the AWG-9 loses the target, the WCS stops guiding the AIM-54 and it simply proceeds by maintaining the same altitude.
The crank, especially if pulled very hard, has the side effect of messing with the AWG-9 antenna elevation, sometimes braking the lock. Since the cranking is quickly completed, usually the lock is restored in a matter of seconds. Nevertheless, those few seconds can make the difference on longer ranges. The solution is dropping the antenna elevation by a number of degrees set depending on TWS mode, range, banking ratio, altitude. There is no value set in stone, due to the number of parameters involved, so practice is the best teacher.
If you are wondering why this is happening, well, I am not sure. It seems that, as the F-14 banks, the antenna pivots around the F-14 horizontal geometrical plane, causing the radar cone to miss the contact, especially in a standard look-down situation. Usually, the harder the bank, the higher the chances to fall into this situation.
TWS Auto, when implemented, may solve this issue.