Dairy King

242fps
26 inch draw
54#
80% LO
6 inch brace
342 grain arrow.

But, I shoot at around 510 grain arrow. How fast do you think this thing would fly? Got a guess at what my KE and all that good stuff would be?

bigbuck90

A arrow that heavy would fly a lot slower...im guessin aroun 220 but i could be way wrong, im not really sure.

Sylvan

A bow shooting a 342 grain arrow at 242 ft/sec carries 44.5 ft/lbs. of KE and 0.37 pound seconds of momentum. If you shot a 510 arrow from the same bow and we assume 100 grains of virtual mass then this bow should shoot this arrow at 206 ft/sec and it would carry 48.1 ft/lbs KE and 0.467 pound seconds momentum. If we assume 150 grains virtual mass it calculates to 208.9 ft/sec with 49.5 ft/lbs KE and 0.473 pound seconds momentum.

gibblet

what, heavier arrow, slower speed, more momentum? more ke? ohmygawad. do people believe yet?

PABowhntr

Not to hijack this thread but do you want to post a little refresher on virtual mass Sylvan? What would be an average figure for a moderate/typical setup on one of today's bows?

Dairy King

I dropped close to 40 fps? Wow. I wasnt expecting that much. [:-]

Black Frog

Don't you remember Arthur's post a year ago (another lengthy discussion) about "What the &$%##$@# is virtual mass?!?"

http://forum.hunting.net/asppg/tm.as...8&mpage=1&key=

Archery pro

here is a calculater



http://www.bowsite.com/bowsite/featu...tion/index.cfm

Sylvan

Here is a good site to learn about virtual mass as well as many other archery physics topics http://homepage.ntlworld.com/joetapley/

I think of virtual mass as the equivalent amount of mass that is accelerated if you were to dry fire the bow. Its kind of the equivalent of all the wasted energy expressed in terms of added weight to be accelerated. When you shoot an arrow it takes energy to accelerate the mass of the arrow plus the virtual mass.

Typically modern compounds will run 100 to 150 grains of virtual mass and of course the lower the better. Here are some values taken from the last 3 issues of Bowhunting World.

Mathews Outback - 91-98 grains
PSE Vengeance - 150-156 grains
High Country TSSR Carbon - 140 - 155 grains

Sylvan

Exactly gibblet! Like I said in the other thread, the archer can't separate momentum and ke. They both go up and down with arrow weight so to argue about which is more important is kind of meaningless to the archer. Heavier simply means more penetration potential and the price is a slower speed and greater trajectory. Whether the increased penetration potential comes as a result of more momentum or more KE is irrelevant.