>if you know something is there, you have a way better chance of tracking it.
Fighter jets can maneuver. For a successful missile launch you need a good enough lock to track the plane precisely as it moves. Just knowing roughly where the plane was a few minutes ago doesn't help all that much when it comes to killing it.
But your fighter jets can know where to look. Supported by all your drones you can send in the flight path. One drone close enough with a heat seeking missile and that was it.
And advanced radar probably also can get a lock, if the operators know something is there.
To keep eyes (or IRSTs) on a maneuvering stealth jet you're either going to need insane numbers of drones or drones that have similar performance to the jet you're tracking. The sky is a big place. Either way, if this kind of thing works at all, it's not going to work out any cheaper than the existing options.
Also, launch parameters for missiles are important. A missile fired from a drone flying at low subsonic speeds has far less energy, and is thus far less of a threat.
"A missile fired from a drone flying at low subsonic speeds has far less energy, and is thus far less of a threat."
The F35 only has a top speed of Mach 1,6 (F16 had Mach 2). And a ground to surface missile also starts at V0 = 0 so less of a threat maybe, but still a great threat. The defense of a stealth jet is not speed, but stealth. When a missile is fired at it, it might survive, but the idea is that there never will be a missile fired in the first place. Drones could negate that.
SAMs are much bigger than anything a drone or fighter jet can launch. Here's one example: https://en.wikipedia.org/wiki/S-400_missile_system This missile weighs about 10x as much as an AMRAAM, for example. That's how it has enough propellant to launch from the ground and still have enough energy to pose a significant threat.
That's right, I wasn't reading carefully. I did not mean a drone should fire a SAM. My point with the SAM was just, they are dangerous, even though they start at V0=0. But yes, they were designed for it. But air to air missiles are also dangerous when fired from a slow helicopter as far as I know ..
Fighter jets can maneuver. For a successful missile launch you need a good enough lock to track the plane precisely as it moves. Just knowing roughly where the plane was a few minutes ago doesn't help all that much when it comes to killing it.