Weapon experts, question for you

[GScholz]

You're misunderstanding. Projectiles "skip" across water just like a speedboat does ... however a speedboat still breaks the water's surface and so did the British bouncing bombs as well. Water provides infinite resistance as long as the projectile's speed is sufficient to create lift by deflecting the water downwards and to the sides. If you look at the films of the dam buster bomb you will notice that a significant portion of the bomb is below the waterline every time it bounces. If it was dropped on a thin aluminium sheet do you think it would skip as well? No, of course not.

[GScholz]

Btw. I shoot guns every week.

[storch]

Originally posted by GScholz
Btw. I shoot guns every week.

  at Nilsen?  I hope not.  The skip thing is semantics

[GScholz]

No at paper targets mostly. The skip thing is not semantics when people try to equate bullets skipping across water with the fantasy of bullets skipping off paper-thin aluminium sheets. A thin aluminium sheet will not deflect a rifle or cannon projectile, even at high angles. Nor will it deflect bouncing bombs or even speedboats for that matter.

[Krusty]

Originally posted by GScholz
No at paper targets mostly. The skip thing is not semantics when people try to equate bullets skipping across water with the fantasy of bullets skipping off paper-thin aluminium sheets. A thin aluminium sheet will not deflect a rifle or cannon projectile, even at high angles. Nor will it deflect bouncing bombs or even speedboats for that matter.

"We're out of ammo and they're still flying!!!"

"Fine.. load" *dun dun DUUUUNNNN* "... the speed boat!"

"No, captain, not that! We're too close! The prop wash alone --"

"I SAID DO IT!"

[GScholz]

[phookat]

LMAO Krusty

[storch]

 Krusty

[Tony Williams]

Originally posted by GScholz
Bullets do not skip off water, nor do they skip off thin sheets of aluminium. However the skin on the wings and most fuselages is curved and therefore a projectile may very well just grace a small portion of the surface, leaving a furrow that makes it look like the projectile skipped off.

We could be getting into some very close definitions here. The original poster said:

Two things struck me as odd. first was that the aircraft's aluminum skin was so very thin (.030-.035?) and secondly that many of the rounds fired at it did not penetrate that thin skin. You could see where they had glanced off leaving the metal stretched and dented but not broken. Very cool display.

Note "stretched and dented". Now if you are right, someone sighting along the bullet furrow should observe that it is perfectly even in depth, all the way - if  you laid a straight rod along it, it should touch at every point. But if the middle of the furrow was even slightly deeper than the front or back, that would clearly show that the bullet had been deflected. Now all we need is someone to check it out...

Tony Williams: Military gun and ammunition website and Discussion forum

[storch]

Tony, I didn't want to continue the discussion because at times these dicussions with Gunther degenerate to name calling.  However a replica of these very distinct indentations is easily enough duplicated.  I have created them myself with any projectiles from a B.B on to a 30.06.  They are the result of a high angle impact against the sheet metal.  At the initial point of impact the indentation is shallow and narrow it widens as the projectile travels and the metal reacts by expanding until the projectile is actually deflected and you end up with an overall shape akin to the silhouette of a lightbulb.  The deepest indentation in the sheet metal is also the widest, where the projectile was glanced off.  I suspect that the sheet metal may act like a trampoline first absorbing the energy of the projectile then releasing same sending it off on a tangent.  The skin is stretched but never broken.

In any event this may be a wonderful excuse to ask for permission to visit Mr. Weeks restoration facility in South Miami and perhaps take some photographs.  I'll ask directly.

[HoHun]

Hi Vulcan,

>The scenario is dead 6 shots from reasonable close range, the theory above is that 90% of shots are richocheting/deflecting off aluminium wings instead of penetrating them (7.62 and 20mm rounds).

Well, I don't expect any worthwhile decrease of weapon effectiveness, and certainly not 90% of the shots deflecting.

I've just checked out a NACA 23012 wing's geometry (typical for the era), and even if you aim right down the wing chord, ca. 90% of the projected area offer an impact angle of larger than 3°.

"Projected area" is the key - any part of the aircraft that's at 3° or less to the line of sight is very hard to hit anyhow.

And 3° is a very narrow angle. Even shooting at a pure 2-dimensional target, at 200 m you only need to move out one wingspan to either side to get out of the "ricochet zone". As real targets aren't 2-dimensional, the ricochet zone is even smaller than that (if it exists at all).

Regards,

Henning (HoHun)

[SunTracker]

.50 cals were reported to bounce off the cowlings of Fw190s by B17 crews.

[GScholz]

Take a look at how thin aircraft skin is:








Anyone who thinks that rifle or cannon rounds would "bounce" off aircraft skin is in serious need of a firepower and penetration demonstration at their nearest army base.

[Crumpp]

.50 cals were reported to bounce off the cowlings of Fw190s by B17 crews.

That is probably due to the armour ring protecting the oil cooler in the front of the FW-190's cowling.  

Crumpp

[GScholz]

Originally posted by Tony Williams
We could be getting into some very close definitions here. The original poster said:



Note "stretched and dented". Now if you are right, someone sighting along the bullet furrow should observe that it is perfectly even in depth, all the way - if  you laid a straight rod along it, it should touch at every point. But if the middle of the furrow was even slightly deeper than the front or back, that would clearly show that the bullet had been deflected. Now all we need is someone to check it out...

Tony Williams: Military gun and ammunition website and Discussion forum

The original poster did not say that.