Quote:
Originally Posted by gunnut
I maybe wrong on this, but I thought the aircraft performing the Cobra is still moving forward as before, just much slower and with the tail pointed in that direction. The jet never reaches 0 speed.
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Sure, the Cobra is a fancy way to reduce speed. And that's exactly what you need to fool the Doppler-radar. You don't have to move at 0 kmh, it's enough if you move say not faster than a helicopter.
The Doppler radar function is based on frequency shift of reflected radio-waves: the faster the target AC is moving, the bigger the shift is, and therefore target's speed/position is calculated more accurately.
On the other hand, if target's speed is small, the frequency shift becomes close to the noise level, making the tracing much more inacurate.
It's a well-known fact, that a hanging helo is not visible to Doppler-radar.