Hello, 
I am looking for advice, or a tutorial on how to rotate a human character 270 degrees on the vertical plane. (Think a back flip that doesn't land right)  A good chunk of the motion the body is in the same position in the air, it simply needs to rotate around. Is there a simple way to do this? So far all my attempts require me to reposition everything for each frame. For the record, I am hand keying this, so there is no mocap data to reference. 

Thank you in advance for your time.

You need to properly sync a Pelvic and Thighs rotation in the air to make it believable.
Mixamo has a few back flip motions which you may use as a reference or built you own motion based on it.

Here I cut about 90 frames in the middle from one of them.



Another one.. probably a better choice for you (called Getting Hit Backward)

I appreciate the reply. I didn't actually need to know what a back flip looked like, I've literally done thousands. What I did need was information on how rotate the body in the program, BUT I figured out what was causing my issue on my own. Thank you for your time.

This might be what you are looking for:
1) Add your Character
2) Add a Box (Create>Primitive Shape>Box).
3) Align the Box to your Character
3) In the Modify tab, Scale the Box to 10.0 (Lock Scale XYZ)
4) Move the box up the Z-axis to the part of the body you want to be the center of rotation
5) Link the Character to the Box
Now when you Rotate the Box, the Character will rotate as well.  You'll need to position arms/legs/etc. accordingly.  You can 'automate' the angle and speed of the rotation by creating starting/ending keyframes.  You can hide the Box, either by making it "Invisible" or "Set as Dummy"

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