viewtopic.php?f=3&t=5839
Does anyone know what methodology was used to obtain the data?
Stored energy in a given bow is constant; excess energy left over from the arrow will be absorbed by the bow resulting varying degrees of hand, elbow shock etc.
Without the relevant data the values below would appear to be irrelevant.
“Some efficiency figures for you Matt lifted from the same article.
125# 44 " flight bow 1548gr arrow - 84.3 %
1067 gr arrow 78.8 %
552 gr arrow 66.1 %
360 gr arrow 60.0 %
203 gr arrow 48.0 %
72 # warbow forgive the typo in the original post it is actually a 49 " bow sorry for the error
1548 gr arrow 90.7 %
1067 gr arrow 88.6 %
522 gr arrow 80.7 %
360 gr arrow 71.6 %
204 gr arrow 57.0 %”
I carried out some tests using my Mandarin Duck recurve which has a draw weight of 31.52# @ 27” DLPP; its stored energy being 358.65 inch-lbs.
The 302.7 grain arrow and 347.2 grain arrow were fletched with 3 x 4 inch shield cut offset feathers.
The 510.8 grain arrow was fletched with 3 x 4 ½ inch banana cut helical feathers. The snap nock on this arrow was tight fit on the bow string which would have robbed performance of a few fps.
For consistency the shooting machine was set up in my workshop. An overhead LED tube was used above the Chrony and a modified release aid was used to loose the arrow.
The images below would indicate that the bows efficiency does not vary a great deal as arrow mass changes.
The spread sheet uses a ‘virtual mass formula’ to predict arrow velocity and as far as I know does not take ‘drag’ into account.
http://www.tap46home.plus.com/mechanics/fdrag.htm
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- 01_Mandarin Duck Unbraced.jpg (28.09 KiB) Viewed 1557 times
- 02_Pedicted Arrow Velocity With Chrony Data.jpg (97.52 KiB) Viewed 1557 times
- 03_Arrow Velocity vs. Arrow Mass.jpg (74.74 KiB) Viewed 1557 times
- 04_Virtual Mass Arrow Formula.jpg (171.26 KiB) Viewed 1557 times
Daryl.