Very true Arthur P. LIke you said, it is very popluar to consider KE as the principle factor in penetration. I use to do the same thing. You hit the nail on the head with your observation. Speed affects KE exponential. For example, a increase in speed of only 25% will double the KE. While a 25% increase in speed only affects momentum by 25%.

I think we can all agree that a light fast arrow is not recommended for maximum penetration. If you are going to hunt Cape Buffalo with a bow (psychological evaluation might be need) you will be instructed to shoot a high poundage bow and a HEAVY HEAVY HEAVY arrow. Now, if KE is the only factor governing penentration then speed would be the ultimate factor with a moderately weighted arrow.

Has there ever been a study done with actual numbers. If not I would like some suggestion on how to do a test. Maybe ballistic gelatin could be used. Varying KE and momentum setups and groups of 3 arrows per set up could be used. 3 arrows of each setup could be shot into fresh ballistic gelation. Each new set up would require a new block of ballistic gelatin. The average penetration of the 3 arrows could be compared with KE and momentum. Maybe we could see a trend and answer the question once and for all.

Any ideas?