The power of my air rifle, what does it mean ?

by **iLukey96** » Tue Mar 26, 2013 12:03 am

Hey Folks!

Just curious, I brought my new air rifle and the power of it is 11.4ft/lbs.
What does that actually mean then ?

Thanks!

by **Tommo** » Tue Mar 26, 2013 1:56 am

Bottom line, at the most basic maths level, if you raise a weight of 1lb up 1ft and drop it the foot pounds of energy = 1ft lb therefore, for example, a weight of 1lb dropped from 12' would be equal to 12 ft lbs. (which is the maximum an unlicensed air rifle can attain).

I'm sure there are many others who can give a more scientific answer but that is as I understand it.

by **iLukey96** » Tue Mar 26, 2013 2:10 am

Tommo wrote:Bottom line, at the most basic maths level, if you raise a weight of 1lb up 1ft and drop it the foot pounds of energy = 1ft lb therefore, for example, a weight of 1lb dropped from 12' would be equal to 12 ft lbs. (which is the maximum an unlicensed air rifle can attain).

I'm sure there are many others who can give a more scientific answer but that is as I understand it.

Hey Tommo!
Thanks for replying.

I kind of understand what you meant by that, but I suppose because I am not the greatest at maths I am still not 100% what it means :P

Thanks!

by **leadpig** » Tue Mar 26, 2013 8:49 am

it is a way of measuring what energy your rifle produces with a known projectile,the calculation is based on the speed and weight of said projectile as it leaves the barrel.the heavyier the pellet/bullet and the quicker it is going will increase the energy levels.
the energy is normally measured in foot pounds ie 11.4 fpe/ftlb,but can be measured in joules as well
in the uk you can not have a rifle capable of producing more than 12 fpe without a fire arms certificate,so your rifle is pretty much spot on,you dont want it much higher as different pellets may put you over the limit
conversion table below,put in weight and velocity and click on energy

http://www.pyramydair.com/article/What_ ... 3145.app03

by **247sniper** » Tue Mar 26, 2013 9:56 am

Feckin he'll Dave, what have you been reading ! :lol:

by **Buffy Vampire Slayer** » Tue Mar 26, 2013 10:03 am

247sniper wrote:Feckin he'll Dave, what have you been reading !

tom gaylord has just given me a headache :shock:

by **Triffid** » Tue Mar 26, 2013 10:55 am

iLukey96 wrote:Hey Folks!

Just curious, I brought my new air rifle and the power of it is 11.4ft/lbs.
What does that actually mean then ?

Thanks!

It's a measure of the energy in the pellet.

Energy is calculated by multiplying the weight of the pellet by it's velocity. In fact it's the velocity squared becuase of 'the laws of physics'.

Energy = Mass x Velocity x Velocity.

Energy (ft/lbs) = Pellet mass (grains) x Velocity (fps) x Velocity (fps)
Correction factor to get all the units the same (450240)

So if you are using a 15 grain pellet, it means your muzzle velocity is 585fps.

In practise, outside of the 'Laws of Physics', what it means is that your rifle is capable of killing small game and vermin such as rabbits, pigeon and rats out to about 40 yards away. If you do your bit and put the pellet in the right place.

IMO the accuracy of the rifle and shooter is more important than the exact energy it produces: a pellet at 9ft/lbs is equally capable if it hits in the right place, but has a more pronounced trajectory.

Triffid