In the rocket world, you always want fins at the back and not the front. Fins move the Center of Pressure back to create stability. The fletching on the arrow does the same thing.

In the missile world they often have small fins up front, frequently called turn fins. These can be deflected to cause the missile to turn but also add a destabilizing effect by moving the CP forward. For stability the CP must be behind the CG. Your planing blades are creating the same effect as turn fins on a missile, I would think mostly due to the "turn fin" effect, not due to destabilization.

The amount of force generated by a turn fin is governed by the side area of the fin and the angle of attack. Aspect ratio does enter into the equation but to a much lesser extent than the side area. Of course, this is what the non-planing head you show is designed to do, reduce the side area.

My take on it would be that for your application, most any shape you want would be acceptable and that the amount of planing would be mostly governed by the side area of the head.

Your rotating head idea brings up an interesting point, if you'll pardon the pun. How loose with the blades be? Would it be loose enough to weather vane? If so that could eliminate the planing. Of course at the same time, the springing of the arrow would also wiggle the blades from side to side and could affect accuracy.

I would also be concerned about the steep angles you have on the blades affecting penetration. As long as you're looking at movable blades, why not make them replacable. Then it's no problem if you wind up bending one.

There are rocketry forums at http://www.rocketryonline.com/ and http://www.rocketryforum.com/ . I'm sure they'd love to get in on the discussion.

Dave