fps to foot pounds

[new to the flock]

How do you calculate fps to foot pounds?

 

NTTF

[kip270]

fps x 2 x weight of bullet/pellet in grains divide by 450240

 

so take air-rifle figures 600fps x 600fps x 14.5grain pellet divide by 450240 =11.59ftlb

[njc110381]

The calculation goes like this:- Multiply the projectile weight in pounds by the square of the muzzle velocity in feet per second (fps), then divide the result by 64. Note that there are 7,000 grains in a pound. So, for a .22 pellet (14 grains) travelling at 600fps the calculation is:-

 

pellet weight :- 14 divided by 7000 = 0.002

squared muzzle velocity (600x600) = 360,000

0.002 x 360,000 = 720 divided by 64 = 11.25 ft/lbs

 

 

Just noticed kip can type faster than me

[new to the flock]

Thanks Guys

NTTF

[new to the flock]

Okay, just worked out a rifle that I am looking at using your 14 grain pellet weight as I have nothing with the weight of the pellets on it. It is not listed on the tins here.

 

This gun is shooting at 1200 fps, so according to both sets of calculations....they were within .5..........the gun should be shooting at 45 foot pounds.

 

Would you say this is heavy enough for squirrels and out to what distance?

 

NTTF

[pin]

Take heed http://en.wikipedia.org/wiki/Muzzle_velocity

 

 

Okay, just worked out a rifle that I am looking at using your 14 grain pellet weight as I have nothing with the weight of the pellets on it. It is not listed on the tins here.

 

This gun is shooting at 1200 fps, so according to both sets of calculations....they were within .5..........the gun should be shooting at 45 foot pounds.

 

Would you say this is heavy enough for squirrels and out to what distance?

 

NTTF

 

Heh, that's about half what a .22lr does at about 50yds - more than enough for squirrel

[kip270]

Okay, just worked out a rifle that I am looking at using your 14 grain pellet weight as I have nothing with the weight of the pellets on it. It is not listed on the tins here.

 

This gun is shooting at 1200 fps, so according to both sets of calculations....they were within .5..........the gun should be shooting at 45 foot pounds.

 

Would you say this is heavy enough for squirrels and out to what distance?

 

NTTF

Nttf, do you reload?? if you have some powder scales just weigh five pellets and see what they come out at.

45ftlb, squirrels look out. Depends on how good your accuracy at what you think is your max range. With a 12ftlb air-rifle i have taken squirrels at 50 yards and clean kills, but it is all to do with accuracy.

 

If you rifle is going that fast try a pellet from 15-18grain but check accuracy

[kdubya]

Okay, just worked out a rifle that I am looking at using your 14 grain pellet weight as I have nothing with the weight of the pellets on it. It is not listed on the tins here.

 

This gun is shooting at 1200 fps, so according to both sets of calculations....they were within .5..........the gun should be shooting at 45 foot pounds.

 

Would you say this is heavy enough for squirrels and out to what distance?

 

NTTF

 

your right in your approximation of FT/LBS however at 45 ish with a 14 grain at 1200fps you are in supersonic territory and I should imagine that the pellet will be highly unstable in flight?

cheers KW

[new to the flock]

Thanks Guys.

 

I think I may have to buy one of these. They are only $125 cdn or around 50 pounds.

 

Dont think I would have too much trouble with the accuraccy after a little time on it, and after I find something that it likes to eat.

 

NTTF

[Lord Geordie]

There is a program called "chairgun" on the internet free too i belelive

 

Simply put in the weight of your projectile the speed of your projectile and IT calculates your FPE

 

It can also help calculate your drop in trajectory

 

Your points of aim near and far

 

your best scope height and heaps more

 

It's a fantastic program

 

LG

[justme]

Hi,

I thought that it was fps x fps (not 2 x fps) x weight divide by 250240 was the way to do it & in the above example it gives 11.59ftlb for a 14.5 pellet at 600fps. Having looked at the other explanation the same gun with the same pellets gives 11.651 ftlb. Not a big difference but it might count. So which is right? Or more importantly which method do the police use as that small difference could make all the diference.

 

justme

[kdubya]

Fps X fps X grains /450240 = Ft Lb.

 

cheers KW

[kip270]

Hi,

I thought that it was fps x fps (not 2 x fps) x weight divide by 250240 was the way to do it & in the above example it gives 11.59ftlb for a 14.5 pellet at 600fps. Having looked at the other explanation the same gun with the same pellets gives 11.651 ftlb. Not a big difference but it might count. So which is right? Or more importantly which method do the police use as that small difference could make all the diference.

 

justme

 

 

Fps X fps X grains /450240 = Ft Lb.

 

cheers KW

 

that's what i meant, didn't type it that well did i

thanks kdubya

[Lancs Lad]

Hi,

I thought that it was fps x fps (not 2 x fps) x weight divide by 250240 was the way to do it & in the above example it gives 11.59ftlb for a 14.5 pellet at 600fps. Having looked at the other explanation the same gun with the same pellets gives 11.651 ftlb. Not a big difference but it might count. So which is right? Or more importantly which method do the police use as that small difference could make all the diference.

 

justme

 

 

Fps X fps X grains /450240 = Ft Lb.

 

cheers KW

 

that's what i meant, didn't type it that well did i

thanks kdubya

 

Sod all that maths..............just get yourself a chrono.....................about 30 quid...

[PestController]

Okay, just worked out a rifle that I am looking at using your 14 grain pellet weight as I have nothing with the weight of the pellets on it. It is not listed on the tins here.

 

This gun is shooting at 1200 fps, so according to both sets of calculations....they were within .5..........the gun should be shooting at 45 foot pounds.

 

Would you say this is heavy enough for squirrels and out to what distance?

 

NTTF

 

Hi NTTF

 

I have an Air Ranger set at 55ft/lbs that does rabbits easily out to 80-90 yards.

I tend to use Bisley Magnums ( .22) as anything else just folds up and is not accurate enough.

Also using the heavier Bismag pellet, you'll get slower muzzle velocity enabling you to get away from the sonic "crack", still maintain a fairly flat trajectory, with awesome hitting power. ( for an air rifle )