Unfortunately, on December 21, all the model airplanes I've flown since the late 70s were instantly transformed into drones by the FAA.
Any eagle that swoops down on my 5' flying wing is in for a rude surprise. A VERY rude surprise as I will have complete freedom of action to outmaneuver him, avoid by simply cranking on 80 mph of straight line speed or turning toward and colliding. The eagle will take the worst of it and I will fly away.
My normal course of action would just be to hit the jets and leave him wondering why some idiot sent him out to catch something that flies much better than he can.
Of course, the idea of what a drone is usually doesn't involve fixed wing radio control planes in most people's minds, in spite of our FAA classification. But you have to wonder why people are all up in arms about the quadcopters. Their maximum duration is usually on the order of ten minutes. Their cameras are wide angle. They make a lot of noise that means that they cannot be used stealthily.
My flying wing has a duration of about a half hour and with larger batteries I could get more like 45 minutes. Gliding silently I can truly be stealthy. My single electric motor is more silent than any quadcopter, even when running. I am still hampered by cameras having too wide a field of view to do any real spying, as if such a thing were even interesting, which it is not.
What you should fear is the new generation of SLR's with 100/1 optical zoom! Put those turkeys on top of a 20' pole and do photography where you can tell the color of someone's eyes at a quarter mile away with unlimited duration, no noise at all! People who are worried about drones need to just get a life.
And the string idea won't work. There is one rule you find out very quickly when flying a radio control airplane. Depth perception isn't. Past about 50' it's about as reliable as betting 00 on a roulette wheel. You can't tell me within a couple hundred feet how far away your plane is. The only rule that works when avoiding obstacles is that if you see blue sky under your plane and over the obstacle you'll most likely miss it.
So it is impossible to entangle the other drone's props with the string. It just can't be done. And why would you spend $500 to dangle a string from a drone?
It occurs to me that proof might be nice. In Utah there is a crazy bunch of fliers from whom I buy my flying wings,
CrashTestHobby.com. These batsoid people get 50 people together with their flying wings, take off en-mass and try to knock each other out of the sky. The flier who has the largest number of kills minus deaths wins. Yes, just about every time a plane which has suffered a high G collision and then crashes to the ground is picked up and tossed back into the air with no damage. Here are 50 of them flying simultaneously TRYING to collide. Notice how rare collisions are even then. One quadcopter trying to target another? Forget it.