.50's from above

[wbs]

It would seem that belly armor would be impervious to .50 caliber rounds, because after all, it is designed to provide the crew protection against Antitank mines, and those are more powerful than .50 caliber rounds.

[jgdpzr]

Originally posted by Compassion:

</font><blockquote>quote:</font><hr />Originally posted by jgdpzr:

I've read and seen accounts of this as well. That belly armour was certainly vulnerable to .50 fire.

I've read accounts of this as well, though a couple eyars ago, I argued this point with Fionn. He pointed out that no matter what first hand accounts might say, there's no denying that the armor on the floors Tigers IS proof of .50 fire... even 8 of them, especially after spending much of it's kinetic energy on he ground.

What is easily beleivable is that these .50's cause damage to tread and roadwheel and drive train causing smoking and crew bailing... As far as the P-47 pilots are concerned, they killed the tank.</font>

[HVAP]

The "kills" as mentioned earlier were most likely diasabled tanks not exactly destroyed. However I want to make one point that the .50s did not shoot directly ahead they were angled according to the pilots desire to intersect fire out at some range in front of the aircraft. So 8 fifties inetersecting at something like the area of a quarter would put a lot of stress on that area. I mentioned this on another post in the Pacific modified B-25s mounted a ton of nose and hull mounted .50s to attack shipping and blow holes in boilers etc. I saw one of those B-25s at an air show sure didnt want to be on the ground or on a boat when that thing was coming at me.

Cheers!

[Michael Emrys]

Originally posted by HVAP:

So 8 fifties inetersecting at something like the area of a quarter would put a lot of stress on that area.

Except that that would not happen under anything short of laboratory conditions. In the first place, the guns on an aircraft were not aimed on a point that small. More like a foot in diameter would be more like it. For any but the best proven shots it might be as much as five or ten feet. Secondly, a pilot in a fast moving aircraft would not be able to keep his aimpoint fixed on a spot that small even if he were trying. At best, a target that had been fired on would look like it had be hit by a large shotgun. More likely, the impact points would stream across the target in a loose, broad line. Even with 6-8 guns firing 1,000 rpm each, you'd probably be lucky to get impact points within an inch of each other, and several inches would be the norm.

Michael

[HVAP]

Thanks for the info I knew they were sighted but I figured actual combat results were not that good. I did not know how close the rounds would hit I was just throwing out a tidbit thanks for enlightening me

[jgdpzr]

Originally posted by Michael emrys:

</font><blockquote>quote:</font><hr />Originally posted by HVAP:

So 8 fifties inetersecting at something like the area of a quarter would put a lot of stress on that area.

Except that that would not happen under anything short of laboratory conditions. In the first place, the guns on an aircraft were not aimed on a point that small. More like a foot in diameter would be more like it. For any but the best proven shots it might be as much as five or ten feet. Secondly, a pilot in a fast moving aircraft would not be able to keep his aimpoint fixed on a spot that small even if he were trying. At best, a target that had been fired on would look like it had be hit by a large shotgun. More likely, the impact points would stream across the target in a loose, broad line. Even with 6-8 guns firing 1,000 rpm each, you'd probably be lucky to get impact points within an inch of each other, and several inches would be the norm.

Michael</font>

[Bastables]

Originally posted by Michael emrys:

</font><blockquote>quote:</font><hr />Originally posted by HVAP:

So 8 fifties inetersecting at something like the area of a quarter would put a lot of stress on that area.

Except that that would not happen under anything short of laboratory conditions. In the first place, the guns on an aircraft were not aimed on a point that small. More like a foot in diameter would be more like it. For any but the best proven shots it might be as much as five or ten feet. Secondly, a pilot in a fast moving aircraft would not be able to keep his aimpoint fixed on a spot that small even if he were trying. At best, a target that had been fired on would look like it had be hit by a large shotgun. More likely, the impact points would stream across the target in a loose, broad line. Even with 6-8 guns firing 1,000 rpm each, you'd probably be lucky to get impact points within an inch of each other, and several inches would be the norm.

Michael</font>

[Rick614]

Gyrene,

My last post on this so as not to beat it to death. How would you get "get rid of their payload and scoot" from my statement of "concentrate on any other thing that putting metal on the target"? I just saying if it was me knowing what all was going on I think I just try to cover the target with lead the best I can and not worry about bouncing bullets off the ground.

As far as this speed of a projectile fired from and aircraft I'm lost. Does a bullet fired from an aircraft going 360mph (440 fps) which normally has a muzzle velocity of 2640fps (2160 mph) now have an initial speed of 3080 fps? Or is the fact that the aircraft is traveling 360mph cancelled out by the fact that once the bullet leave the barrel it sees what appears to be a 360mph headwind. Remember the bullet is dumb and it does not know if it is being fired from a stationary platform into a 360 mph headwind or if the wind is calm and the platform it is being fired from is traveling 360mph. Does the bullet end up traveling 2640 fps with reference to the ground but only 2640-440 or 2200 fps with reference to the aircraft?

The only thing I know for sure is that the 30mm in the A-10 doesn't need much help. I have read accounts that pilots are told to maintain ample speed above stall speed when firing because the recoil from a substained burst is like firing a small retro rocket.

[JonS]

Originally posted by Bastables:

... For instance Mortain the classical example cited to prove that aircraft are efficient Panzer killers. Claims by the RAF’s 2nd tactical air force claims 140 tanks destroyed/disabled, US 9th army air force 112. These numbers actually exceeded the number deployed by the Germans. In reality only 46 tanks were lost and only 9 of these had been hit by air weapons...

Ian Gooderson's 'Air Power at the Battlefront', London 1998, contains a couple of case studies.

Regards

JonS

[Michael Emrys]

Originally posted by Rick614:

Does a bullet fired from an aircraft going 360mph (440 fps) which normally has a muzzle velocity of 2640fps (2160 mph) now have an initial speed of 3080 fps?

More or less. The critical observation is that although that extra speed bleeds off quickly, a bullet fired at a target from a moving aircraft will still hit that target at a higher velocity than one fired from a static gun at the same range under the same conditions.

Michael

[Charlie Rock]

Field manuals I have seen relate that a .50 cal round can go through one inch of steel plate at 90 degrees, inside 200 meters. I would guess an AP round would go through a bit more. AP rounds were not to my knowledge that common in ground mount .50s, but anecdotally I have heard that they were more common in aircraft, especially if you were hunting against tanks.

Let's assume, for argument's sake, an AP round is 30% more effective than ball. Now we are at about 30mm penetration. If a P-47 fired a one second burst, that is 80 rounds. If at close range, half did not miss left or right, you might have as many as 40 (50%) ricocheting under the tank. 1 in 5 rounds would be tracer, so assume 32 rounds have AP capability. Let's say that half the kinetic energy was absorbed by the ground, so we now have 32 rounds which can penetrate 15 mm, as opposed to 30mm. If the rounds are glancing against the underbelly, probably won't penetrate. If a couple bounce upward at a sharp angle, it would be close. (near 90 degree penetration against the underbelly) As few as three or four rounds zinging around in a turret could cause a lot of damage. I would say with a great deal of luck and a great deal of ammo it would be possible. Occasionally. Not the most efficient method, but possible.

I would think a high angle pass against the engine deck would be more effective, without ricochet trick shooting.

Personally, I would not go around contradicting pilots who saw things with their own eyes, years before I was born.

[Gyrene]

Rick, we seem to be out of sync here, and I'd like you to know that I'm not trying to flame you or anything like that.

I just can't see a young man probably flying over enemy territory making a strafing run at 300+ mph knowing that all sorts of people are shooting at him with no altitude and if anything goes wrong he will be just a smudge on the landscape with a dozen other things to think about would concentrate on any thing other than putting metal on the target.

Not all pilots were newbies and thinking of their safety only. A 22 or 23 year old pilot could easily have 40+ missions in his name. The best pilots or gunners are the ones who can act beyond the ordinary to get the job done.

We should not be to quick in dismissing anecdotal evidence.

Take the case of riverboat crews in Vietnam: They developed the technique of skipping 40mm grenade rounds in the water to give the rounds enough time to arm and to skip underneath the foliage. This was not in any US Navy manuals and was not officially taught, but was very common practice.

Give another 20 years and many by-the-book scholars will flatly deny that this was ever done, as it was never sanctified by official publication, regardless of what the veterans have to say.

Maybe fighter pilots in WWII tried to skip bullets under tanks and maybe they didn't, but if they didn't it wasn't because they were too scared to try a particular tactic, but more because they thought it wouldn't work.

Gyrene

[Rick614]

Gyrene,

Point taken. You did start an interesting topic.

[Guest PondScum]

Originally posted by JonS:

Ian Gooderson's 'Air Power at the Battlefront', London 1998, contains a couple of case studies.

A very interesting read, especially the interrogation of prisoners of war. It seems that the 3-inch rocket from a Typhoon or Mustang was the one thing that scared German tankers enough to make them abandon their tanks - not because it hit much (it didn't!), but because the thought of what it would do to them if it DID hit didn't bear thinking about. Think of it as a terror weapon: if it causes your enemy to abandon his weapons on the battlefield, it worked, regardless of whether it "hit" or not.

[illo]

Let's assume, for argument's sake, an AP round is 30% more effective than ball. Now we are at about 30mm penetration

Tony Williams said .50cal AP round has penetration of 20mm at optimum agle (90degrees) from 200 meters.

I am sure he can solve your questions.

He's author of "Rapid Fire: The development of automatic cannon, heavy machine

guns and their ammunition for armies, navies and air forces"

Details on his military gun and ammunition website:

http://www.quarry.nildram.co.uk

Military gun and ammunition discussion forum:

http://forums.delphiforums.com/autogun/messages/

[JonS]

Originally posted by PondScum:

...if it causes your enemy to abandon his weapons on the battlefield, it worked, regardless of whether it "hit" or not.

Except that abandoned weapons - particularly things that are hard to lose in the undergrowth like, say, a Tiger - can be un-abandoned quite easily. Most air attacks happened far enough back from the frontlines that there would be no direct interferance once the planes had left.

The only casualty then would be loss of cohesion (only temporary at best) and more importantly loss of time - once its gone, it ain't coming back.

Regards

JonS

Edit: the usual suspects

[ March 14, 2002, 03:18 PM: Message edited by: JonS ]

[YankeeDog]

Originally posted by Rick614:

As far as this speed of a projectile fired from and aircraft I'm lost. Does a bullet fired from an aircraft going 360mph (440 fps) which normally has a muzzle velocity of 2640fps (2160 mph) now have an initial speed of 3080 fps? Or is the fact that the aircraft is traveling 360mph cancelled out by the fact that once the bullet leave the barrel it sees what appears to be a 360mph headwind. Remember the bullet is dumb and it does not know if it is being fired from a stationary platform into a 360 mph headwind or if the wind is calm and the platform it is being fired from is traveling 360mph. Does the bullet end up traveling 2640 fps with reference to the ground but only 2640-440 or 2200 fps with reference to the aircraft?

In a word, yes. This has already been sort of covered, but to be absolutely clear: To use your terminology, while the bullet is certainly "dumb", it does "know" that it was fired from a moving platform relative to the target.

Imagine I am holding a large lead weight out the window of a car moving 60mph. My hand and the lead weight are travelling in a path that will intersect with your head. a microsecond before the weight makes contact with your head, I let go of the weight. The weight hits your head at 60mph, yes?? So, from a certain point of view, it weight "remembers" that it was once attached to a platform moving 60mph. The same holds true if I throw the weight at your head the moment before it hits, rather than just releasing it. If I throw the weight at 20mph, the weight hits your head at 20mph + 60 mph = 80 mph.

The aerodynamics (and therefore the momentum and kinetic energy at any given range) of a bullet fired at 2640fps from a platform moving 440fps is exactly the same as the aerodynamics of a bullet of identical composition fired at 3080fps from a stationary platform, assuming that the air is calm. This is basic Newtonian mechanics. Without going too far into a high school physics lesson, all motion is relative.

It is also true that, as previously mentioned, relative to initial muzzle exit velocity, a projectile fired at a higher velocity will lose speed faster than one fired at a slower velocity - air resisitance goes up by the power of 4 relative to velocity, so the difference is considerable. This is true of all high velocity projectiles, though. Basically, the faster they get, the faster they slow down. Exactly how much of the "additional" velocity has been cancelled out by air resistance goes up with the distance the bullet has to travel to reach its target, then. I can't give specifics as to exactly what the velocity of a .50 cal round at a given range would be if fired from a platform moving at 440 fps relative to one fired from a stationary platform without detailed data on the round's aerodynamics. Suffice it so say that the additional velocity is not completely "cancelled out" by air resistance. Otherwise, AT gun designers wouldn't bother to try for higher velocity guns, as the effect would be "cancelled out" by air resistance.

The other very minor effect that helps a projectile fired from a strafing aircraft is the fact that the projectile is generally fired downward at its target. This means that gravity actually helps it accelerate as it moves towards the target (or at least not slow down as much). This effect is probably negligible in the case of a .50 cal MG round, though. I doubt it makes much more than a 2-3fps difference and therefore is of interest only to anal physicists. Some aircraft-launched weapons, such as WWII era armour-piercing bombs and modern "bunker buster" bombs, rely on this effect for a substantial amount of their penetration capability.

I'm still curious to know how much difference 440fps muzzle velocity makes in terms of armour piercing capability at, say 300 meters. If I knew where to start, I'd do the research myself. . .

Cheers,

YD

[Charlie Rock]

Illo,

I do not know who Tony Williams is.

The Department of the Army says .50 ball goes through one inch plate. That's 23 mm. AP will go through more.

If you can convince me that Tony Williams knows more about .50 cals than the US Army, OK.

Anyway, I still stand by this: It is technically possible (But infrequently likely in practice) to ricochet a .50 AP round through the belly of a tank.

[illo]

Charlie,

I suggest you to send email to him. I know nothing about .50cals to be honest. He has done quite much research on that subject.

I'm sure he appreciates if you can point him being wrong. He makes his living from writing on subject.

Btw. Bottom of most german tanks tanks had circa 30mm of armor i can't see how round ricochetting from road could penetrate. Think about angles involved and also how ground hit affects in shape of bullet.

[ March 15, 2002, 12:55 AM: Message edited by: illo ]

[JonS]

Originally posted by Charlie Rock:

The Department of the Army says .50 ball goes through one inch plate. That's 23 mm. AP will go through more.

If you can convince me that Tony Williams knows more about .50 cals than the US Army, OK.

Is that with current, or WW2 ammo? If it is the former, then this Tony Willians may indeed know more about the latter that the DOA.

Regards

JonS

[illo]

This is just stupid cut and paste thing and proves nothing, but it shows what is my impression of .50cal performance. I think this picture is originally from panzer Elite.

.50 cal penetration against 15mm plate.

If these figures are right it would seem almost impossible for fighter to shoot through top armor of PzKpfw.IVh.

60 degree dive at 250m from ground with 300mph isn't very healthy.

[ March 15, 2002, 01:13 AM: Message edited by: illo ]

[PzKpfw 1]

Theirs an account in Parkers To Win The Winter Sky from an Panther TC IIRC that tells of being caught on the road by US Fighters that made continous strafeing runs on his Panther.

Basicly he said IIRC they sat their buttoned up till the US planes got bored strafeing, & then drove away.

Regards, John Waters

[gredeker]

Some of the info in this thread indicates that the 23mm penetration figure is for a modern SLAP round. It's a .30 cal tungsten penetrator in a .50 cal sabot.

[Michael Emrys]

Originally posted by Charlie Rock:

Illo,

I do not know who Tony Williams is.

The Department of the Army says .50 ball goes through one inch plate. That's 23 mm. AP will go through more.

If you can convince me that Tony Williams knows more about .50 cals than the US Army, OK.

Anyway, I still stand by this: It is technically possible (But infrequently likely in practice) to ricochet a .50 AP round through the belly of a tank.

A couple of points here:

First of all, an inch is closer to 25.4mm.

Secondly, it will penetrate that much (of an unspecified compostion) armor only if it strikes it at 90°. A riccochet off the ground onto the belly of an armored vehicle will most likely hit it at an angle more acute than 45°, although this is impossible to predict for any given bullet.

Thirdly, as someone has already mentioned earlier, a riccochet will have already lost much of its energy before contacting the armor. Just how much would be highly variable depending mostly on the hardness of the surface you were bouncing it off of and at what angle it strikes the ground.

Finally, I would have to agree that a penetration under those circumstances is indeed just possible. But the likelihood is so miniscule that it is not worth discussing in regard to its possible inclusion in CM.

Michael

[Tomb]

you dont have to penetrate to kill thier is a report i have somewhere which compares the 60lb HE an AP rockets as fired by the typhoon while the AP in theory would get the most kills in practice the HE did since it had a habit of removing the turret from the tank if it hit near and since removeing the turret was rather a effectice way of killing a tank despite no armour pentration being achieved. i think i have remebered it right i,ll see if i can dig it up , its a PRO document.

Tomb