WHAT IS FPE?? — AN EXPLANATION

Ever wonder what FPE is?
Everyone talks about it –>>>”My gun produces 50 foot pounds energy”.
FPE = Foot Pounds Energy

Energy is Force through a Distance. (force times distance)

Imagine a brick on a air hocky table (a frictionless surface).

If you push the brick with a force of 5 pounds for a distance of one foot, then you have imparted 5 foot pounds of energy to the brick.

If you push the same brick with a force of 10 pounds for a distance of one foot, then you have imparted 10 foot pounds energy to the brick

While the brick is moving on the air hocky table, this energy is stored as velocity and mass of the brick.

When the brick hits the other side of the air hocky table, the brick releases this stored up energy as an impact. The more foot pounds of energy you put into the brick when you push it, the harder it impacts the other side of the table.

The same thing happens when you shoot your pellet gun.
Air pressure applies a force to the pellet.
The pellet is pushed with this force for the length of the barrel.

Again: FPE = Force X Distance
In your pellet gun, force (on the pellet) is produced by air pressure in the barrel.
In your pellet gun, Distance is the length of the barrel.

If you have a 24 inch barrel (2 feet), and the air pressure in the barrel produces 25 pounds of Force on the pellet, then you have 50 Foot Pounds Energy at the muzzel. 2 feet X 25 pounds = 50 fPE

Now that you have a pellet flying through the air with 50 FPE of energy, What happens when it impacts something?

If you shoot that pellet into something soft, like balistics gel, and it stops in 6 inches (.5 foot), then the balistics gel has applied 100 pounds of force to decelerate the pellet.

Again: Force X distance = Energy.
The moving pellet has 50 FPE and stops in 1/2 foot, so the interaction between the pellet and the gel has produced 100 pounds of force.

50 FPE = .5 foot X 100 pounds force.

Whatif you shoot that pellet into something harder, like a piece of wood?

Say, that same 50 FPE pellet impacts the wood and penitrates 2 inches.

2 inches = .16 foot
50 / .16 = 300 pounds force to punch 2 inches into the wood.

The faster you stop that pellet, the more force it takes.
Thats how you can punch holes in hard items.

I hope this isnt too confusing.

For those of you that understand this stuff, you know that this explanation is somewhat simplified –> forces here are actually average force down the length of the barrel.

Mark