The 50 cal. Buff Gun Laser Myth, Part 2: Ballistics andEnergy

[Widewing]

Originally posted by eskimo2
The B-17 tail gun round:
When a 50 cal. bullet leaves the muzzle of the tail gun in a B-17, it actually has a slower airspeed than a 50 cal. bullet fired from a fixed ground fired gun (about 367 fps slower if the buff is flying at 250 mph).  This means that it will lose speed and energy at a slower rate than the ground fired gun (even though it has less speed and energy as soon as it leaves the muzzle).  It's target (the P-51), is actually moving toward the point in space from which the 50 cal. bullet was fired, so this round has less than 1000 yards to travel before colliding with the P-51.  When it collides with the P-51, it instantly gains 367 fps to its speed and energy state (the speed of the P-51).

Er, your entire premise is flawed. There is no change in muzzle velocity whatsoever due to the movement of aircraft. Muzzle velocity is a function of the weapon only. Moreover, if both aircraft are flying at the same speed, their relative velocity is the same. I believe that you have misunderstood the physics of the issue. If the P-51 was flying at a speed 200 mph faster than the B-17, you can add that velocity difference into the total energy equation. But, at the same relative velocity, there is no difference. Everything is relative.

My regards,

Widewing

Widewing

[hitech]

Widewing think about the speed of the bullet realitive to both the air and the gun.



HiTech

[Dux]

Widewing, imagine two pickup trucks traveling 65 mph on a highway, one about 100 feet ahead of the other. In the back of each truck is a man throwing baseballs at the other truck. I think you can see how the man in the front truck has an easier throw.

[eskimo2]

Originally posted by Dux
Widewing, imagine two pickup trucks traveling 65 mph on a highway, one about 100 feet ahead of the other. In the back of each truck is a man throwing baseballs at the other truck. I think you can see how the man in the front truck has an easier throw.

Exactly.
Assume they each could pitch at 65 mph.
The ball pitched from the guy in the front truck (pitching backwards) would have an airspeed of 0.
The ball pitched from the guy in the back truck (pitching forwards) would have an airspeed of 130.

eskimo

[Widewing]

Originally posted by hitech
Widewing think about the speed of the bullet realitive to both the air and the gun.



HiTech

Well, it certainly helped reading the entire post, rather than stopping after the first paragraph.

Of course, since both aircraft are moving in a fluid, aerodynamic effects relate directly to the speed relative to that fluid. So, yes, I agree with the conclusions. Nonetheless, what got my attention was the misuse of terms. "Muzzle velocity" is still uneffected by speed within the fluid. Bullets still emerge from the muzzle at the same velocity, regardless of speed within the fluid. However, relative velocity, relative to the second aircraft, is effectively reduced.

Again, I apologize for not reading further into the post where the intent of meaning becomes clear.

My regards,

Widewing

[Dux]

You're missing it, Eskimo... how much air-induced drag would that theoretical 0-mph ball have? Almost none. The truck in back is driving into the rearwards-thrown ball at a speed of 65... that's a closing speed of 65 mph.
Now the ball being thrown forward... sure, it's initial airspeed is higher, but with that comes a much higher level of drag, and with drag comes a level of ballistic "wandering" (for lack of a better term at the moment). All the while the truck in front is moving away from the ball coming in from behind.
So when it comes to plane in front vs. plane in back... the bullets from the rear plane lose alot more energy in its travels.

front plane = same muzzle velocity + minimal decrease in energy

back plane = same muzzle velocity + greater decrease in energy

lol, it would be so easy if I could draw a picture

[eskimo2]

Widewing,
No problem.  I can see how it could be read that way.

Dux,
We're really talking about the same thing.

eskimo

[Dux]

lol, Eskimo, I think I just confused myself. I'm sure we are talking about the same thing.

Never mind!

[hitech]

I think I just confused myself

My normal mode ot thinking.

[eskimo2]

Wait...?
What were we talking about?
I'm surly confused, but I can't figure out who confused me...

LOL  

eskimo

[bozon]

nice post eskimo2!
how do you manage anything with this measurment system i don't know... there is the MKS or CGS system you know

writen by niklas:

Whethter your plane is hit by a round with 2000ft/sec or 1000ft/sec is not so important imo, especially with an AP round. In both cases it will pass through the structure, if no armor is present. In both cases the AP round will leave a little hole, and kinetic energy is not completly - maybe only to a minor part - transfered into damage.

the damage done by a bullet is not the size of a hole it leaves. those bullets that hit nothing but aluminium do no significant damage. to do the damage they need to hit critical systems or the structure beams for causing structural failure. then the energy matters a lot. also the weight of the bullet is significat factor since a heavy bullet will transfer more energy to a hard target (do to better momentum for the same energy) than a lighter bullet wich will just bounce of it. this is why 0.5 bullets break planes and 0.3 bullets turnes them into a fishing net.

Bozon

[MadBirdCZ]

BTW what was the convergency settings on the 'buff' and the 'P-51' ?

With convergency set at 650 (so the longest possible in AH) the 'buff' will hit the 'P-51' almost at convergency (also the buff's gun barrels are much closer to one another than on the wing mounts of the P-51) so the hits will be more tightly packed in closer area. At the other hand the P-51 burst will cross-over at the 650 mark but it has to travel longer distance but the hits will be much more separated... ?  I don't know... I always hated mathematics and stuff... But shouldnt this be considered as a factor in this discussion as well?

Just my $0.02

[eskimo2]

Bumped for the "Shooting" thread.

eskimo

[DREDIOCK]

Originally posted by Karnak
Westy,

My ammo counter showed that I had fired more than 200 rounds.

I saw 8+ hit sprites.

Gotta remember you can put 1000 rounds into something and still not destroy it. If you dont hit anything vital dont expect it to pop.
Its not so much IF you hit it but WHERE you hit it.

And just cause it didnt pop  or smoke doesnt mean you didnt damage it.

Drediock