±Recent Visitors

Recent Visitors to Com-Central!

±User Info-big


Welcome Anonymous

Nickname
Password

Membership:
Latest: HighestAce
New Today: 0
New Yesterday: 0
Overall: 6648

People Online:
Members: 0
Visitors: 373
Total: 373
Who Is Where:
 Visitors:
01: Home
02: Community Forums
03: Member Screenshots
04: Community Forums
05: Community Forums
06: Downloads
07: Community Forums
08: Photo Gallery
09: Member Screenshots
10: Community Forums
11: Community Forums
12: Home
13: Community Forums
14: News Archive
15: Downloads
16: Home
17: Home
18: Community Forums
19: Community Forums
20: Community Forums
21: Home
22: Community Forums
23: Home
24: Downloads
25: Home
26: Community Forums
27: Community Forums
28: Community Forums
29: Member Screenshots
30: Member Screenshots
31: Statistics
32: News
33: Community Forums
34: Downloads
35: Statistics
36: Photo Gallery
37: Community Forums
38: Community Forums
39: Photo Gallery
40: Community Forums
41: Community Forums
42: Community Forums
43: Community Forums
44: Community Forums
45: Home
46: Home
47: Community Forums
48: Home
49: Home
50: Home
51: Home
52: Home
53: News Archive
54: Community Forums
55: Community Forums
56: Community Forums
57: Photo Gallery
58: Photo Gallery
59: Community Forums
60: Community Forums
61: Community Forums
62: Community Forums
63: Community Forums
64: Community Forums
65: Home
66: News Archive
67: Community Forums
68: Community Forums
69: Community Forums
70: Member Screenshots
71: News Archive
72: Community Forums
73: Home
74: Home
75: Home
76: Home
77: Community Forums
78: Community Forums
79: Home
80: Home
81: News Archive
82: Home
83: Home
84: Home
85: Home
86: Home
87: Community Forums
88: Member Screenshots
89: Photo Gallery
90: Home
91: Community Forums
92: Home
93: Home
94: News Archive
95: Photo Gallery
96: Community Forums
97: Home
98: Home
99: Home
100: Community Forums
101: Home
102: Home
103: Photo Gallery
104: Community Forums
105: Photo Gallery
106: Downloads
107: Home
108: Community Forums
109: Downloads
110: Home
111: Photo Gallery
112: Home
113: Member Screenshots
114: Community Forums
115: News Archive
116: Member Screenshots
117: Home
118: Community Forums
119: News Archive
120: Home
121: Statistics
122: Member Screenshots
123: Home
124: News
125: Community Forums
126: Home
127: Community Forums
128: Community Forums
129: Community Forums
130: Home
131: Community Forums
132: Home
133: Community Forums
134: Home
135: Home
136: News
137: Home
138: Home
139: Member Screenshots
140: Photo Gallery
141: Community Forums
142: Community Forums
143: Home
144: Home
145: Downloads
146: Community Forums
147: Photo Gallery
148: Community Forums
149: Home
150: Home
151: Home
152: Home
153: News Archive
154: Home
155: Home
156: Home
157: Home
158: Statistics
159: Home
160: Home
161: Community Forums
162: Community Forums
163: Home
164: Community Forums
165: Community Forums
166: Home
167: Home
168: Downloads
169: Home
170: Community Forums
171: Community Forums
172: Home
173: Community Forums
174: Home
175: Member Screenshots
176: Home
177: Home
178: Home
179: News Archive
180: Member Screenshots
181: Community Forums
182: Your Account
183: Member Screenshots
184: Home
185: Your Account
186: Community Forums
187: Community Forums
188: Community Forums
189: Home
190: Home
191: Community Forums
192: Member Screenshots
193: Community Forums
194: Member Screenshots
195: Community Forums
196: Home
197: Photo Gallery
198: Community Forums
199: Home
200: Home
201: Home
202: Community Forums
203: Community Forums
204: Downloads
205: Community Forums
206: Community Forums
207: Home
208: News Archive
209: Member Screenshots
210: Home
211: Home
212: Home
213: Community Forums
214: Photo Gallery
215: Home
216: Home
217: Home
218: Community Forums
219: Home
220: Community Forums
221: Member Screenshots
222: Home
223: News Archive
224: Community Forums
225: Home
226: Member Screenshots
227: Home
228: Downloads
229: Home
230: Home
231: Home
232: Member Screenshots
233: Community Forums
234: Member Screenshots
235: Home
236: Home
237: Community Forums
238: Community Forums
239: Home
240: Home
241: Community Forums
242: Community Forums
243: Home
244: Home
245: Community Forums
246: Home
247: Statistics
248: Home
249: Home
250: Community Forums
251: Home
252: Community Forums
253: News
254: Home
255: News
256: Community Forums
257: Home
258: Home
259: Home
260: Community Forums
261: Member Screenshots
262: Community Forums
263: Community Forums
264: Community Forums
265: Community Forums
266: Community Forums
267: Home
268: News Archive
269: Member Screenshots
270: Photo Gallery
271: Home
272: Home
273: Home
274: Home
275: Member Screenshots
276: Community Forums
277: Your Account
278: Community Forums
279: Home
280: Home
281: News Archive
282: Home
283: Home
284: News Archive
285: Home
286: Community Forums
287: News Archive
288: Photo Gallery
289: Home
290: Downloads
291: Community Forums
292: Photo Gallery
293: Community Forums
294: Community Forums
295: Community Forums
296: Member Screenshots
297: News Archive
298: Community Forums
299: Community Forums
300: Community Forums
301: Community Forums
302: Home
303: Community Forums
304: Photo Gallery
305: Home
306: Community Forums
307: Member Screenshots
308: Photo Gallery
309: Home
310: Home
311: News Archive
312: Community Forums
313: Home
314: Community Forums
315: Community Forums
316: Home
317: Community Forums
318: Community Forums
319: Home
320: Home
321: Photo Gallery
322: News Archive
323: Community Forums
324: Community Forums
325: Home
326: Home
327: Member Screenshots
328: Community Forums
329: Home
330: Community Forums
331: Home
332: Community Forums
333: Community Forums
334: Community Forums
335: Community Forums
336: Community Forums
337: Community Forums
338: Community Forums
339: Community Forums
340: Home
341: Community Forums
342: Community Forums
343: Downloads
344: Home
345: Home
346: News Archive
347: Community Forums
348: Community Forums
349: Photo Gallery
350: Home
351: Community Forums
352: Photo Gallery
353: Community Forums
354: Downloads
355: Downloads
356: Downloads
357: Photo Gallery
358: Member Screenshots
359: Home
360: Community Forums
361: Community Forums
362: Community Forums
363: Community Forums
364: Community Forums
365: Community Forums
366: Member Screenshots
367: Home
368: Community Forums
369: News
370: News Archive
371: Home
372: Community Forums
373: Community Forums

Staff Online:

No staff members are online!
Armor penetration formula
The AFV ASSOCIATION was formed in 1964 to support the thoughts and research of all those interested in Armored Fighting Vehicles and related topics, such as AFV drawings. The emphasis has always been on sharing information and communicating with other members of similar interests; e.g. German armor, Japanese AFVs, or whatever.
Go to page 1, 2  Next
Post new topic    Reply to topic    Printer Friendly Page     Forum Index ›  AFV News Discussion Board

View previous topic :: View next topic  
Author Message
blair
Power User

Offline Offline
Joined: Jan 24, 2006
Posts: 87

PostPosted: Sun Apr 15, 2007 4:05 am
Post subject: Armor penetration formula

A long time ago I had cme across an article that described a formula regarding the increased resistance of armor depending on the degree of angle. I'm sure I have my numbers mixed up but basically the formula stated that If you took a a plate of armor 2 inches thick and then angled it by 25 degrees the armor would then have the same penetration resistance depth of 4 inches of vertical armor.

The higher the angle then the higher the resistence depth.

Does anyone know any more about this principle/theory?
Back to top
View user's profile
JimWeb
Power User

Offline Offline
Joined: Jan 24, 2006
Posts: 1439
Location: The back of beyond
PostPosted: Sun Apr 15, 2007 9:29 am
Post subject: Re: Armor penetration formula

Blimey this is really basic geometry!!!

Pick up a book which will represent our armour plate - measure its width then angle it at 45 degrees and measure it from corner to corner - That how thick the armour becomes along the horizontal....

Rolling Eyes

_________________
TTFN
Jim

If your not a member of JED then your
not serious about anything military..

***********************
www.jedsite.info
JED Military Equipment
***********************
Back to top
View user's profile Visit poster's website ICQ Number
bsmart
Power User

Offline Offline
Joined: Jan 23, 2006
Posts: 2523
Location: Central Maryland
PostPosted: Sun Apr 15, 2007 11:55 am
Post subject: Re: Armor penetration formula

Where is Lorrin (from the old board) when you need him Rolling Eyes

If I understand your question Jim has the basics laid out pretty well. When I explain this on tours at Aberdeen I use my hand spaced about3" apart first vertically then at an angle. A 45 degree angle gives you about 1.707 times the thickness that vertical plate will, a 60 degree angle doubles the thickness. This is all geometry , Sines & Cosines (depending on if you are measuring the angle from the horizontal or vertical)

There would be a higher chance of the round 'glancing off' as the angle increases but I'm not sure this would be easy to calculate especially since the shape of the nose and the relative hardness probably play into the factoring.

And if you hit an angled plate (say the 47 degree nose of a Sherman) at an angle off of dead ahead (say 45 degrees off to the side) the angle effect is compunded. ( you get thickness * 1.7 (approx factor for 47 degree armor * 1.7 factor for the angle shot) or a total increase in thickness of 2.89.

_________________
Bob Smart ([email protected])
Back to top
View user's profile Send e-mail
JWB2
Power User

Offline Offline
Joined: Jan 25, 2006
Posts: 199

PostPosted: Sun Apr 15, 2007 7:29 pm
Post subject: Re: Armor penetration formula

IIRC ricochet or "skip" starts when the slope is 45* or greater. Firing tests have shown that resistance can actually degrade when the slope exceeds about 56*. I imagine these facts heavily influenced the slope of both the Sherman and the Panther glacis plates.
Back to top
View user's profile
JimWeb
Power User

Offline Offline
Joined: Jan 24, 2006
Posts: 1439
Location: The back of beyond
PostPosted: Mon Apr 16, 2007 9:30 am
Post subject: Re: Armor penetration formula

- JWB2
IIRC ricochet or "skip" starts when the slope is 45* or greater. Firing tests have shown that resistance can actually degrade when the slope exceeds about 56*. I imagine these facts heavily influenced the slope of both the Sherman and the Panther glacis plates.


Yes but rounds have been designed to overcome this by having flat angled fronts under ballistic caps to enable them to dig in.

Cool

_________________
TTFN
Jim

If your not a member of JED then your
not serious about anything military..

***********************
www.jedsite.info
JED Military Equipment
***********************
Back to top
View user's profile Visit poster's website ICQ Number
clausb
Power User

Offline Offline
Joined: Jan 25, 2006
Posts: 146

PostPosted: Mon Apr 16, 2007 10:08 am
Post subject: Re: Armor penetration formula

- blair
A long time ago I had cme across an article that described a formula regarding the increased resistance of armor depending on the degree of angle. I'm sure I have my numbers mixed up but basically the formula stated that If you took a a plate of armor 2 inches thick and then angled it by 25 degrees the armor would then have the same penetration resistance depth of 4 inches of vertical armor.

The higher the angle then the higher the resistence depth.

Does anyone know any more about this principle/theory?


Goes like this:

Y/cos(Z)=X

where Y is the thickness of the armour plate
where Z is the angle of the armour, with vertical=0
and X is the effective thickness of the armour.

As an example using the frontal hull armour of the Soviet T34 , you get

Y=45mm
Z=60 degrees

and thus:

45/cos(60)=90

meaning that the distance the projectile has to travel through the armour plate is doubled when the plate is sloped at 60 degrees.

However......

That is not by any means equal to the actual resistance of the armour plate in any condition. Far from it. To even begin to approach that issue, you need to take into account a large number of factors including armour quality and hardness, projectile type (AP, APC, sub-caliber, HEAT etc.), projectile design, projectile caliber, projectile hardness and a lot of other elements.
The problem is mainly that while a perpendicular hit on the armour plate will spend most of its energy on going through the armour plate, once the projectile hits a sloped surface, it will have a tendency to move away from the plate and under the right conditions simply bounce off. Whether it bounces or not depends among other things on the shape of the projectiles nose: a pointed nose will tend to bounce, a flat nose will tend to dig in. It also depends on the relationship between the diameter of the projectile (d) and the thickness of the armour (t): if the so-called t/d ratio is more than 1 (say, 45mm of armour hit by a 37mm round) hitting, the projectile will be more likely to bounce off. If the t/d ratio is less than 1 (say, 45mm of armour hit by 75mm projectile) then the projectile will be less likely to bounce off.

It soon gets very complicated....... Smile

I'm deeply suspicious of the idea that an angle of more than 56 degrees will degrade performance, at least not in general. If that was the case, then tanks would have 55 degree slopes on their front hull and no more, which is clearly not the case. The T34 had 60 degree slope on the front hull and post-war tanks tend to get as much slope as possible, just look at Soviet designs. Also, US tanks like the M48 (60 degree front hull) and the M60 (65 degree front hull) shows an increase in slope over the WWII designs (M4 Sherman 56 and 47 degrees, M26 Pershing 56 degrees).

Claus B
Back to top
View user's profile
LeeW
Power User

Offline Offline
Joined: Jan 26, 2006
Posts: 61

PostPosted: Mon Apr 16, 2007 11:09 am
Post subject: Re: Armor penetration formula

In addition once a projectile starts to penetrate it will tend to turn toward the orthoganal.

Face hardened vs homogenious can effect this as well.

For naval vessels there some info at:
www.navweaps.com/index...x_tech.htm
and of course:
www.navweaps.com/index...nathan.htm
which has some formulas and programs as well as info.

Unfortuantly I don't know of a simlar site for AFVs some of this will relate but exactly how is not my area of expertise.
Back to top
View user's profile
JWB2
Power User

Offline Offline
Joined: Jan 25, 2006
Posts: 199

PostPosted: Tue Apr 17, 2007 12:43 am
Post subject: Re: Armor penetration formula

Yes but rounds have been designed to overcome this by having flat angled fronts under ballistic caps to enable them to dig in.

That only happens if the projectile is harder than the armor.

I'm deeply suspicious of the idea that an angle of more than 56 degrees will degrade performance, at least not in general.

That is the result of a firing test conducted by the US Army. IIRC it was 90mm vs Panther type armor so it probably has a lot to do with undermatch. Post war tank armor was desiged to deal with HVAP and early APDS.
Back to top
View user's profile
clausb
Power User

Offline Offline
Joined: Jan 25, 2006
Posts: 146

PostPosted: Tue Apr 17, 2007 5:22 am
Post subject: Re: Armor penetration formula

That is the result of a firing test conducted by the US Army. IIRC it was 90mm vs Panther type armor so it probably has a lot to do with undermatch. Post war tank armor was desiged to deal with HVAP and early APDS.


But the T-34s armour wasn't.....

90mm projectile vs 80mm of Panther frontal armour gives a T/D of 0.88 which is not exactly a massive "undermatch", in fact it is in the same ballpark as, say, a German 75mm vs a late-war Sherman hull at 63mm (T/D 0.84). In the latter case, your logic would dictate that hitting the Shermans armour at an angle of 40 degrees from the side would have a better chance of penetring than a hit at 30 degrees from the side. That sounds rather counterintuitive to me.....
I've yet to see an actual test result, official penetration data or an emperically based penetration formula that would result in what you describe - resistance of armour degrading at angles over 56 degrees. So unless you can point to the exact tests, I'd have to say that it is either a fairy tale or at least a misunderstanding.

Claus B
Back to top
View user's profile
Doug_Kibbey
Power User

Offline Offline
Joined: Jan 23, 2006
Posts: 4678
Location: The Great Satan
PostPosted: Tue Apr 17, 2007 8:33 am
Post subject: Re: Armor penetration formula

- bsmart
Where is Lorrin (from the old board) when you need him Rolling Eyes


We'll remember you said that, Bob...especially if he actually shows up and registers to post. Wink (Be sure to notify Bushy, he'll need to lay on an extra terabyte or two of bandwidth). Alas, we don't have Russ on hand (owing to other "distractions" at the moment, lucky him) to keep him in check if he does.

...and I'm on my way out of the country for a couple of weeks, so if his apparition appears....handle it! Mr. Green
Back to top
View user's profile Visit poster's website Photo Gallery
bsmart
Power User

Offline Offline
Joined: Jan 23, 2006
Posts: 2523
Location: Central Maryland
PostPosted: Tue Apr 17, 2007 9:18 am
Post subject: Re: Armor penetration formula

Hey, I never had a problem with Lorrin. I didn't agree with all his theories (Heck I'm not sure I even understood all his theories Rolling Eyes ) but he did bring a passion and dedication to the discussions.

Have a good trip (you gotta arrange for a layover in the Philly/ Baltimore/DC) region on one of them so we can visit Aberdeen) and we'll try to keep everyone under control (or at least keep them from parking the tanks on the zoomies runway)

_________________
Bob Smart ([email protected])
Back to top
View user's profile Send e-mail
Joe_D
Power User

Offline Offline
Joined: Jan 29, 2006
Posts: 2068
Location: Razorback Country
PostPosted: Tue Apr 17, 2007 9:59 am
Post subject: Re: Armor penetration formula

Doug,

Alas, we don't have Russ on hand (owing to other "distractions" at the moment, lucky him)


I was wondering how Russ was doing, good to here he's OK, I miss his posts.

Joe D
Back to top
View user's profile Photo Gallery
piney
Power User

Offline Offline
Joined: Jan 24, 2006
Posts: 2330
Location: Republic of Southern New Jersey
PostPosted: Tue Apr 17, 2007 2:08 pm
Post subject: Re: Armor penetration formula

I miss Russ too. no fun not having to warn against spit takes

Jeff Lewis
Back to top
View user's profile Send e-mail
Doug_Kibbey
Power User

Offline Offline
Joined: Jan 23, 2006
Posts: 4678
Location: The Great Satan
PostPosted: Tue Apr 17, 2007 4:03 pm
Post subject: Re: Armor penetration formula

- Joe_D
Doug,

Alas, we don't have Russ on hand (owing to other "distractions" at the moment, lucky him)


I was wondering how Russ was doing, good to here he's OK, I miss his posts.

Joe D


I spoke with Russ recently, and am happy to report that his absence is due to his having discovered romance that is occupying a lot of his time, which inexplicably, he is finding preferable to the company of a bunch of fellow curmudgeons. "Bully for him", I say! We mean to do a tour of the El Monte collection soon (when I get in off the road for more than two weeks at a time Rolling Eyes ) but he sounded great!

I miss his humor as well.....

This update brought you courtesy of the Flagship Lounge at Chicago O'Hare Airport....
Back to top
View user's profile Visit poster's website Photo Gallery
JWB2
Power User

Offline Offline
Joined: Jan 25, 2006
Posts: 199

PostPosted: Wed Apr 18, 2007 12:50 am
Post subject: Re: Armor penetration formula

- clausb
That is the result of a firing test conducted by the US Army. IIRC it was 90mm vs Panther type armor so it probably has a lot to do with undermatch. Post war tank armor was desiged to deal with HVAP and early APDS.


But the T-34s armour wasn't.....

90mm projectile vs 80mm of Panther frontal armour gives a T/D of 0.88 which is not exactly a massive "undermatch", in fact it is in the same ballpark as, say, a German 75mm vs a late-war Sherman hull at 63mm (T/D 0.84). In the latter case, your logic would dictate that hitting the Shermans armour at an angle of 40 degrees from the side would have a better chance of penetring than a hit at 30 degrees from the side. That sounds rather counterintuitive to me.....
I've yet to see an actual test result, official penetration data or an emperically based penetration formula that would result in what you describe - resistance of armour degrading at angles over 56 degrees. So unless you can point to the exact tests, I'd have to say that it is either a fairy tale or at least a misunderstanding.

Claus B

I got the info from C.G. Erickson a few years ago at one of the visits to Littlefields.
Back to top
View user's profile
Display posts from previous:   
Post new topic    Reply to topic    Printer Friendly Page    Forum Index ›  AFV News Discussion Board
Page 1 of 2
All times are GMT - 6 Hours
Go to page 1, 2  Next



Jump to:  


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You cannot download files in this forum