In my recovery thread above, I mention that it is a myth. There is no void space between the lungs and the spine. One lung is slightly larger than the other although I cannot tell you which one without going back and reading up on it. You can send an arrow under the spine without severing the spinal cord however you will clip at least the top of one lung. Though this may not be a killing shot necessarily, the void spot is in fact a myth. I've recently come to understand that you can actually send an arrow through both lungs and not kill an animal like a deer. We all know that broadheads kill by hemoraging. In the larger lobes of the lungs, back and high their is less blood vessels there than lower and forward closer to the heart. It is possible to send an arrow through these lobes without calapsing the lungs and without catching enough blood vessels to cause bleed out. I wouldn't have believe this except for the book I'm reading to train my tracking dog.

It shows autopsies of whitetail lungs with broadhead scars in them. That is why it is in the utmost importants to use extremely sharp broadheads. The duller the broadhead the easier it is to slide past a vein, vessel, arterie without actually cutting it. I hope everyone has seen the rubber band examples. It's also important to use the largest cutting diameter that your setup will allow you and still get good penetration.

The larger the cutting diameter, the better chance of hemoraging and collapsing the lungs.