Blood Hawks are transport helicopters that bring Raven troops into an area. They carry quite a few Soldiers, or even a Leadfoot. Though heavily armored, you can still destroy Blood Hawks and the people inside of them.
Before anyone can deploy, Jacob has a chance to blast the group of Soldiers inside a Blood Hawk. Use charged Arcshot bolts to fry everyone as they're huddled inside the chopper. This is a very efficient way to win a fight before it even starts. Then everyone should shoot toward the Blood Hawk's rotor to destroy the chopper before it leaves. This grants bonus experience for the team, and killing five choppers gets you a challenge reward.