Bummer about your glider. Im guessing that was your first dog fight.[&:]
Im pretty sure Red Tails are very territorial and you invaded his airspace. By scaring or taking your glider out, he thought he would have less compitition for food. JMO
I saw a similar incident here in NC some years ago. Luckily though that glider just suffered some covering damage. What to do about it. I dont know. Most people just steer clear of birds of prey when possible.