steve_b_wales Posted July 11, 2013 Report Share Posted July 11, 2013 Is there a formula that I can convert ft per second to ft/lb? I want to check my FAC air rifle and a few others on my chronoraph. Steve. Quote Link to comment Share on other sites More sharing options...
Beardo Posted July 11, 2013 Report Share Posted July 11, 2013 http://www.pyramydair.com/article/What_is_Muzzle_Energy_August_2003/5 Quote Link to comment Share on other sites More sharing options...
fabarm gamma boy Posted July 11, 2013 Report Share Posted July 11, 2013 Will your chrono not give you a ftlb reading if you combine pellet weight and fps? Gotta be honest i know very little on.thos subject, but im sure yhe pw massive will have you clued up in no time ! Atb fabarm Quote Link to comment Share on other sites More sharing options...
steve_b_wales Posted July 11, 2013 Author Report Share Posted July 11, 2013 http://www.pyramydair.com/article/What_is_Muzzle_Energy_August_2003/5 Cheers. Quote Link to comment Share on other sites More sharing options...
JonathanL Posted July 11, 2013 Report Share Posted July 11, 2013 Is there a formula that I can convert ft per second to ft/lb? I want to check my FAC air rifle and a few others on my chronoraph. Steve. You need the bullet weight as well. Multiply the velovity by its self, divide that by 450400 then mulitply the result by the weight in grains. The result is the energy in foot pounds. J. Quote Link to comment Share on other sites More sharing options...
wymberley Posted July 11, 2013 Report Share Posted July 11, 2013 You need the bullet weight as well. Multiply the velovity by its self, divide that by 450400 then mulitply the result by the weight in grains. The result is the energy in foot pounds. J. Yep, that's a better way of doing it. PyramydAir is OK for air rifle but for rifle, if you try to multiply the whole top line before dividing by the 450436, you'll dump the calculator because of the higher velocities. Quote Link to comment Share on other sites More sharing options...
steve_b_wales Posted July 11, 2013 Author Report Share Posted July 11, 2013 Thanks for the advice. Quote Link to comment Share on other sites More sharing options...
GingerCat Posted July 11, 2013 Report Share Posted July 11, 2013 Its 450240; the constant of gravity. For example 8g x 8g x 600fps / 450240 will give u the foot pounds. I'm sire the odd slip on numbers won't make a huge difference but that is the fiqure so u may as well use it. Quote Link to comment Share on other sites More sharing options...
wymberley Posted July 11, 2013 Report Share Posted July 11, 2013 Its 450240; the constant of gravity. For example 8g x 8g x 600fps / 450240 will give u the foot pounds. I'm sire the odd slip on numbers won't make a huge difference but that is the fiqure so u may as well use it. Not that it matters in the slightest, but just out of interest it is 450436. 7000 times 32.174 (international gravitational acceleration) divided by 0.5 equals. Quote Link to comment Share on other sites More sharing options...
GingerCat Posted July 11, 2013 Report Share Posted July 11, 2013 (edited) I have no idea. However it serves exceptionally well for the purposes, I unddtstanu that the late and great author or airr rifles and pistols, that I read as a child, used this formula and having followed it, it is the same as any other in results that others have used. Hence I quote the fiqure Edited July 12, 2013 by GingerCat Quote Link to comment Share on other sites More sharing options...
JonathanL Posted July 15, 2013 Report Share Posted July 15, 2013 Its 450240; the constant of gravity. For example 8g x 8g x 600fps / 450240 will give u the foot pounds. I'm sire the odd slip on numbers won't make a huge difference but that is the fiqure so u may as well use it. I always used to use 450240. However, I believe that 450400 is the more precise figure, for some reason. I'll dig out where I read that. J. Quote Link to comment Share on other sites More sharing options...
wymberley Posted July 15, 2013 Report Share Posted July 15, 2013 I always used to use 450240. However, I believe that 450400 is the more precise figure, for some reason. I'll dig out where I read that. J. Have a shufti at the internationally agreed SI units and you'll see that the equivalent figure you're looking for is 32.174 and then do the maths. Quote Link to comment Share on other sites More sharing options...
activeviii Posted July 15, 2013 Report Share Posted July 15, 2013 It is 450240 Extreme Spread (-ES-) Hi - Lo Subtract the slowest shot from the fastest. For example: 3010 - 2990 = 20 FPS Energy Calculation Average velocity X Average velocity X Weight of bullet in grains ÷ 450 240 = _____ft. lbs Quote Link to comment Share on other sites More sharing options...
Scottoj18 Posted July 15, 2013 Report Share Posted July 15, 2013 Does this help http://extorian.co.uk/shooting/pellets.html Quote Link to comment Share on other sites More sharing options...
steve_b_wales Posted July 15, 2013 Author Report Share Posted July 15, 2013 Thanks to all for your help and advice. I'm going to put all my rifles through the chromo' asap. Quote Link to comment Share on other sites More sharing options...
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