I think about 150 mph would be sufficient for most of the tests, I am not sure what range terminal velocity would fall into.
I put the bulk of my energy into bow building and have had good success there as far as world records go but have always treated the arrows almost like an afterthought when in fact, they are at least 50% of the equation. I would build about 100 arrows the month before the shoot and arrive a few days early to shoot them and see which ones worked best. The results were never anything I could put a pattern to. I would just like to refine my process a bit.
Not sure if you can get any useful data, or how it will help if you do. I suppose you could improve fletching to minimize drag but do you need to test whole arrows for that? How much drag can you reduce after the initial flexing when an arrow is released, it’s just a long cylindrical body. If you’re trying to find out if the surface texture of the shaft matters I’d think distance tests would tell you if there’s a significant difference.
It is the shape of the arrow shaft I am mostly concerned with. Roughly like a torpedo as far as tapers go. Not a straight cylinder such as what we see used by modern bows. The widest part is usually slighty behind the tip. and narrows to the back. But little differences seem to have a large effect.
Hanging it vertically means you don’t really need to worry too much about balancing it - you could either suspend it on a thin rod that extends up from a measuring device underneath the bottom of the vertical wind tunnel, or a wire that hangs it down from the top - I don’t think you need to attach it to the centre of mass, just the axial centre.
Probably the rod version would be most accurate if you can engineer it, because the support will be in the wind shadow of the arrow, but a really thin wire probably won’t make appreciable difference (and you could probably find a way to measure the effect of the wire on its own, then subtract that)
I realize HBDC has been banned, but what he’s describing here is testing whether the center of pressure (CP) is behind the center of gravity (CG), not checking drag. The string is tied at the CG, and if you can spin it around and it tracks, the rocket should be stable. See Peak of Flight Newsletter : Apogee Rockets, Model Rocketry Excitement Starts Here