How many mph does B-25H lose when firing cannon?

[bj229r]

That's a misconception.

When ammo multiplier is turned UP, the ammo does not weigh more than the standard ammo loadout would weigh. Otherwise you'd have P-47s weighing in at 150,000lbs and never go anywhere.

Yep you right, has it always been that way?

[Krusty]

Always.

HTH rooms since day one were running a million x ammo multipliers, flies like "1x weight" onboard.

[Masherbrum]

Spooky

http://en.wikipedia.org/wiki/AC-47_Spooky

Since it fired out the side...hard to slow it down. Now push it sideways?

She was at Thunder Over Michigan in July.   My pop, son and I walked through her.   Gatling Guns still attached and looking as badass as ever. 

[5PointOh]

Not this is scientific data, but my neighbor (Passed away 2 months ago at 85 ) worked on the B-25H main guns (along with turrets).  In a discussion he mentioned the the recoil on the 25H in level flight was enough to slow the plane down.  He also said, and I quote "That son of a Biscuit would shake the whole Flipping plane, you'd swear the damn wings were going to rip off".  Little cleaned up, but you get the picture. 

[boomerlu]

Also, you're not just looking at the projectile, it's the giant jet of expanding gasses that project the shell as well. A space shuttle is extremely massive, and heavy, but it only takes a tiny burst of jets (thrusters) to move it about. A plane flying in-air can be slowed by the gasses shooting forward from gun barrels.

The space shuttle only takes a tiny burst of jets to move around because there is no air resistance in space. Due to conservation of angular momentum, the shuttle will spin unimpeded although its velocity vector would be approximately the same. This is why "dogfighting" in any type of real space combat would be pretty boring - every spacecraft could essentially point its nose at you at will (though the velocity vector may take quite some time to change).

As far as the giant jet of expanding gases - the whole point of those gases is to transfer momentum from the gun platform (the aircraft) to the projectile. Assuming those gases transfer momentum at 100% efficiency and ignoring possible drag effects, you do not need to consider the gases AT ALL, as conservation of momentum then insures that all that momentum went from the plane into the projectile.

Of course it's not possible that momentum is transferred 100% efficiently, but even so, I doubt the momentum loss from an inefficient propellant mechanism can be significant enough to throw the deceleration estimate off too much. This part I'm not sure on, as I'm not familiar with the actual details of projectile cartridges and how efficiently momentum is transferred, but I'm guessing gunmakers have made it a point to refine their designs over the years so as to transfer momentum as efficiently as possible. More oompf from the same amount of chemical.

But to make an analogy to the space shuttle turning using thrusters is just absolutely faulty.

Edit: As to your original question - you can get a basic idea by just multiplying the projectile speed and projectile mass. This will give you momentum transferred. Then just divide the momentum by the airplane mass to get the instantaneous loss in airspeed. Since the B25H doesn't fire its big gun continuously, you don't need to consider thrust or gravity - you will instantly lose that amount of airspeed. The thrust/gravity aspects only matter insofar as how quickly you gain that speed back.

Even with HTC's advanced physics modeling, I doubt they model the jet of gases, so you can probably just ignore that part. If they do model it, then it only matters assuming the jet was actually significant due to an inefficient firing mechanism, which I again doubt.

[33Vortex]

Expanding gases coming out of the gun barrel is just a side effect, of sorts. All the acceleration of the projectile that will occur, is while the projectile go down the barrel toward the muzzle and once outside the barrel it will hit v0 and decelerate from there on. The deceleration of the plane is because of the acceleration of the proj forward, and the expanding gases escaping the barrel muzzle at high velocity, also directed forward. If you want to be exact about it, it's not the plane accelerating the projectile forward, but the expanding gases in the barrel. These gases work both ways directed by the barrel forward against the projectile and backwards toward the weapon itself (don't know the english term) and the aircraft it's fixed in.

The conservation of momentum in the case of the space shuttle is because it operates in vacuum, airplanes do not. So the space shuttle can burn thrusters for 0.1 second and still rotate a full 360 degrees since there is no atmosphere slowing down the continuous motion. The space shuttle is at "rest" with the gravitational pull equal to the acceleration force by the orbital trajectory it's in. An aircraft travelling through the earth's atmosphere will rarely achieve a true state of equillibrium, but will always have a number of forces pulling it to either direction be it turbulence, drag, thrust, lift, gravity or any type of control surface output to alter the flight path. So an aircraft is not comparable to the space shuttle as they operate in completely different conditions.

Just trying to clarify what boomer said. Not that I felt it is really needed but for the sake of clarity.

[boomerlu]

We must be the nerds of our squad, Turner.

[Ack-Ack]

Not that this brings up anything to the discussion but look how cramped the B-25H was.  It must have been terribly uncomfortable being the tail gunner, having to rest on your knees like that.  I didn't know that the waist gunner manned both waist guns, thought both positions were fully crewed.




ack-ack

[Karnak]

All I know is that if you get an Me262 up to maximum sustained speed in AH and then fire all the guns, it slows down quite a lot.