First off, thanks very much to whoever it was that gave us the B-25G and H mod. ~S~
However, I have to ask, do you have some bit of information that states that the big gun's rate of fire is one round every twelve seconds? I'm aware that the gun was manually reloaded, but twelve seconds seems extremely slow. I was just watching WWII footage of soldiers firing and reloading an anti-tank gun. It took less than half the time. It takes less time to reload a Howitzer. Even if it took longer to reload the gun in the B-25, would it really take more than twice as long?
As it is now, I can't fire that thing more than once in a strafing pass. That just doesn't seem right at all. With it's 21 rounds it'll take about twenty minutes to expend all that ammunition with repeated passes.
BUT!!! B-25-h and G's had a radar that allowed them to fire at targets starting at one+ miles out
On the radar...
Late H navalized version models had them for sure. I'm not 100% sure the G had the radar. As for some/most of the 345th BG G models, they removed the 75mm mm gun and replaced them with 2 50's.
from what ive read from various sources it averaged about 1 round every 6 seconds on a strafing run. However, the cannons were pretty unwieldy and most were removed and replaced by twin .50's.
I know the cannons were often replaced with 50's, but that is completely irrelevant to the point, and I would really like to stick to the point.
By the way, who is it that gave us the 25G/H mod? I'm most interested to know what he has to say about this.
As for rate of fire...
The gun used on the B-25's was a variation of the 75mm L/40 used on the earlier Sherman tanks. I found some references giving a "Shell weight" of about 15lbs for AP rounds. I don't know if that includes the case and powder or not, and I'm not really sure how much an HE warhead would weigh. So lets just say that the loader on the B-25's is dealing with a 20lbs complete round.
For comparison: The loader in an the Abrams or Leopard tanks has a 120mm round to load. AP rounds weigh in at about 40lbs for a 1980's vintage round and about 55lbs for a current AP round. HEAT, MPAT, and Cannister rounds all weigh in at about 50lbs.
A loader in an Abrams tank is expected to be able to pull a round from the ready rack, turn it through 180 degrees so it faces the proper way, shove it in the breech, get himself clear of the recoil path, and arm the weapon, in under 10 seconds. Most loaders do so faster.
I would say that your B-25 loader could probably have his gun reloaded in under 10 seconds rather easily. Maybe even half that time. He has a lighter round to work with, and as his shells would be brass cased rather than combustible, he might be able to skip the steps of having to pull one from a rack for the first reload and instead simply have it sitting on his lap or held in his hands. ('Lap-loading')
Aircraft....
Tight confines not designed for this....
Bouncing up and down and side to side.....
Time to recoup after loading, pulling back (broken arms=bad), grabbing another shell from the rack, orientating it, driving it home......
Tension of combat.....
etc..
You guys are asking for "optimum" results......Optimum equals "uber", average equals correct, below average equals porked......Just because Bob could do this, or Tom that, or Jimmy could pick his nose while chewing gum as he hopped on one foot and slam shells into the breech at 6r/m doesn't mean "everyone could"......In fact, if it was not outrageously exceptional it would not of even been mentioned.
The ROF of the 75mm gun on these aircraft impressed me greatly. Leave it alone IMLTHO.
WHat we need more is a field modified D strafer, with the belly turret turned drop tank.
K2
Speaking as a pilot, airplanes don't generally bounce around enough to have a significant impact on the loading of the gun.
And cramped spaces are irrelevant if you don't have to move around. The guy loading the rounds would have both the gun and the ammo right in front of him.
The Soldier loading the tank round did so in about six seconds, and he had to turn around, open the door, swing the (120 mm) round 180 degrees while turning back around to load it. The B-25's cannoneer would simply have to reach forward to grab a shell and lay it down into the tray.
The more I look into it, the more inclined I am to accept the one-round-every-3.3-seconds figure that I was originally skeptical of. One round every twelve seconds is obviously too slow in the extreme.
