wood arrows & compound bows

[Tartar Horde]

Hello Timelord, energy transfer is a complicated matter when comparing arrows and has caused many Archaeologist a sleepless night. To honestly answer the question do wooden shafts deliver higher kinetic energy than Olympic style alloy/carbon arrows you would have to get both the wooden shaft and your Aluminium one to weigh the same in grains to start with, then use exactly the same fletchings and points to make each arrow as near to identical in weight as is humanly possible. Next you would shoot those arrows exactly the same draw length through a chronograph. I reckon because of the thinner profile of an Alloy/Carbon shaft as compared to a standard 11/32 wooden shaft,the Alloy/carbon will have less energy lost to air friction and so just might have the edge in energy due to it's slightly faster velocity. There are other factors at play with this subject, for instance two archers shooting the same bow, same arrows, same draw length, put them through a chrony and there will be a difference that is purely down to how they loose the string. I definitely agree with you about arrow flex at the target, there is a video on youtube that shows a mongol bow shooting through a melon and the arrow wiggles and snakes its way through.
Some experimentation was carried out by Mike Loades, a respected historian and weapons tester and put into a Military channel programme called "weapons of war" (I will check and send you link). They got some of the best Atlatlists in the USA, the likes of Bob Berg to test flint and obsidian darts on a dummy wearing the correct grade (munitions) and style of Conquistador armour. None of the darts pierced the breastplate, but they did make some impressive dents, although in reality these would soaked up by the padded Gambesons etc worn under them, so the answer is no Timelord I don't think the Aztec Atlatls could pierce Spanish plate, HOWEVER!!!! having read the accounts of the Conquistadors they talk about "arrows" causing the most damage, and being responsible for festering wounds and having the ability to penetrate armour. I believe this may be the source of the confusion and due to a misunderstanding of the word "Armour" and what this pertains to. The Conquistador authors do not differentiate between plate and maille, and as generally only the highest ranking soldiers would have breast plates, that leaves the majority wearing mail over padded garments. The accounts talk of arrows made of cane that will shatter and splinter, driving the sharp parts through their armour (like flechetes). Interestingly the writers talk about "darts" and "arrows" so they were aware of the difference between Atlatl and Bow.
I can send you the links to these sources if you wish to read them, but you could do no better than read the eyewitness accounts of Bernal del dias/z who participated in the conquest of Mexico with Cortez. You can find it at "Project Gutenberg" which has a vast online library containing most of the "classics" in downloadable format, highly recommended.