[II./JG1_Krupinski]

~SALUT~ Thunderbolt!

This is a rather interesting thread! I prompted me to do a little technical research on the 50 cal. Have to say it been fascinating!

While it wasn't my intention, I found some details that makes me wonder how the author came up with 400 hp reduction because of recoil.

If we consider a 50 cal bullet, 800 gr / 52 g with a muzzle velocity of say, 2895 ft/s or 882 m/s, this would result in 15000 ft-lbf or 20,000 J of energy stored in that bullet (E=1/2 MV^2).

Since Sir Isaac Newton states that for every action there is an equal and opposite reaction, this energy has also been exerted to the recoil system, the slides and ultimately the plane.

Since horsepower is a unit of work over time, we need to depress that trigger for a specified amount of time so we can compare energy (Joules) to Power (Horsepower/JoulesPerSecond)

So if we fire 1 gun for 1 second that equates to about 27 horsepower exerted on the recoil system. If the recoil system of the gun was fixed no moving parts, and strong enough to not break - then all that energy / work would be transferred to the plane - thus slowing it down. But, the recoil system of the gun takes that energy and converts it to heat and uses some of the power to reload the gun. So, it's safe to assume not all 27 HP is transferred to the plane, slowing it down. But of course, some amount is actually slowing it down.

Multiplying 27 HP for one gun by a total of 6 guns we'd get 162 HP. Now, I thought this couldn't be right but when I thought about it, it really makes sense.

If 6 guns did in fact exert 400 HP of power on a P51, then a single gun would be exerting 66 HP. We as humans, would not be able to fire a BMG. 66 HP is the equivalent lifting 36000 pounds, one foot in one second.

So I wonder want additional factors the author is considering? maybe additional forces created by drag induced from maybe the guns causing the plane to slip?


*** EDIT ***

This may come in use when comparing aircraft. This is how we can compare the weight of force between plane X and plane Y. Of course, it doesn't take into account the explosive power of exploding cannon rounds. But WoF, is a key element in determining a plane match up.

Best regards,

Raven