Fact or fiction about 50 cal machine gun

Most fighters of the era used 6-8 AN/M2 .50 cals, so the effect would have been more pronounced in an aircraft.  Also, jeeps look small, but they still weigh over a ton, I don't think a .50 would knock one over that easily.

Fiction, viz.: 

BTW, WWII Jeep curb weight: 2,293 lb (1040 kg)

A WWII P-47 pilot, who attends our club meetings on a regular basis, told us that when he "opened up" with his 50s he did see a drop in air speed.

Jim

Also, consider that the airplane is in the air, without the resistance of sitting on the ground.  In the air, a P-47 could be affected in its path of flight by a crosswind, but that same wind, if blowing across the jeep, will not blow it over.

Absolutely correct.

Jim

As Newton said; To every action there is an equal and opposite reaction.  Then what would be the opposite force being applied against the mass and velocity of this aircraft from the firing of eight (as in the case of a P-47) 50 cals? I don't think that it would be much, it isn't like they are retro rockets.

I have read that firing the main gun on a a10 warthog would slow it down.also weren't most jeeps fitted with a 30 cal?

try shooting a 152mm main gun round on an M-551 SHERIDAN

I knew a gentleman who was a P-61 gunner. He said that firing the 4 20mm's cost 10-15 knots airspeed.

I once was next to a very small guy at the outdoor range who had the biggest .44 revolver I've ever seen. When he fired with a two hand grip, he staggered back a couple of steps and I suddenly felt down range.

Does firing the guns of a AC-130 push the aircraft sideways? I've read that firing the main guns of an Iowa class battleship does not push it laterally even though in photos it looks like it does. There again it is mass as a big factor.

Did you know that multiple barreled installations of naval rifles fire slightly out of sync for a reason? I wonder if that same problem occurs with multiple MG's in the wing of an aircraft.

The .50 cal. Ma Deuce is not quite generating that much recoil. The dynamics of its operation will dissipate a good amount of that recoil energy by their motions. Yes it jumps around quite a bit on a pintle mount, but I do no honestly see it tipping a jeep or similar 1/4 ton vehicle... I think the pintle mount would likely break loose from the floorboard before any tipping would occur on flat ground...

Makes you wonder what that cannon in the nose of the B-25's would do.

GMorrison

Did you know that multiple barreled installations of naval rifles fire slightly out of sync for a reason? I wonder if that same problem occurs with multiple MG's in the wing of an aircraft.

Gulf of Aden (May 14, 2005) - Fire Controlman Steven Baumgartner from Oelwein, Iowa, assigned to Combat Systems Department aboard the guided missile cruiser USS Normandy (CG 60), fires the twin .50 caliber machine gun during a Pre-Action Calibration Fire (PACFIRE) exercise. Normandy is currently conducting Maritime Security Operations (MSO), in the 5th Fleet area of responsibility. U.S. Navy photo by Photographer's Mate 1st Class Robert R. McRill. [This Image was released by the United States Navy with the ID 050514-N-5526M-012.jpg]

But again, water is far more dense than air, and not compressible.  This means that the battleship encounters a LOT more resistance than the plane in the air does.  Also, AC-130 crews have said that the 105 in particular does affect the flight path a bit when firing--the 105 has a recoil force of over 10,000 pounds!  I recall that B-25 crews would say the same thing about the 75mm cannon firing, that it would feel like the plane slowed down a bit when firing.    Either way, its important to remember that anything in the air is encountering far less resistance than something firmly on the ground, and even less than compared to a ship in the water.  

As far as the A-10 goes, the recoil thrust is approximately equal to the thrust of one engine.  Remember that the firing time is only a second or so, so the total drop in speed is not much, but if you could sustain the firing for a period of time, it would be like only having 1 engine, instead of 2.  Same thing would be true of the P-47, or any other multiple gun battery.  I have a hard time believing that the recoil of the 50 cal could tip or damage a Jeep on a stable surface.

The A-10 gives a 3 second burst so the plane stays in the air and does not stall. In these 3 seconds about 150 uranium cored bullets, the size of a coca cola bottle, are thrown at a tank/car/building. The recoil is heavy...

But the pic of the 2 barrel gun... must be great to fire them...

the projectile off the A-10's 30mm gun is not the size of a coca cola bottle. It is roughly about the size of 2 "C" cell batteries end to end. But far heavier.

Anyway, they make ugly holes in my car...

stikpusher

But far heavier.

     Lead = 11.34  g·cm⁻³
 Uranium = 19.1   g·cm⁻³
                                                Call it at 60%

Yes I used to have one of those slugs that I had picked up as a young soldier in an impact area way back when... long gone now...

The burst limit on the A-10 is not for the plane flying, but to make sure the barrels do not overheat.  Even if it was to make sure the plane did not slow down, the A-10 can fly perfectly well on one engine, which with the gun firing, it still has the equivalent of available..  The max speed would be less, and the fuel efficiency would be horrible, but the plane could stay in the air.  Also, the magazine only has (I think) about 20 seconds of firing time, so  you do not want to waste bullets.  The shell the GAU-8 uses is a 30 mm round that at its heaviest is about 15 oz.  The cartridges weigh about 1.5 lbs.  Recoil is reported at 10,000 lbf thrust.  The 50 cal is a lot less, but still has a kick

stikpusher

The .50 cal. Ma Deuce is not quite generating that much recoil. The dynamics of its operation will dissipate a good amount of that recoil energy by their motions. Yes it jumps around quite a bit on a pintle mount, but I do no honestly see it tipping a jeep or similar 1/4 ton vehicle... I think the pintle mount would likely break loose from the floorboard before any tipping would occur on flat ground...

Spot on.  The current crop of .50 BMG sniper rifles weigh in at about the 20-30 pound range, and shooting them has been described as being about on par to a full power 12 gauge slug load.  Granted the muzzle break has a big hand in reducing recoil, but it suffices for the point I am about to make.......the M2 is listed in at 84 pounds.  This is even before you load on a full can/belt of rounds.  So we are talking about probably 100 pounds of solid weight resisting the recoil of the .50 BMG.  Combined with the internal operating system/spring it is no surprise a single M2 firing won't buck a jeep over or break a pintle mount.