steelmtn Posted March 5, 2002 Share Posted March 5, 2002 I am in college and taking physics (calculus based) where the professor wants the students to write a 2-4-page paper on any physics subject. I am kicking around the idea of comparing the effective kill distance between two WWII tanks. I have to write my own equations based on the knowledge I have gained so far in the class and as much real data that I can gather. I would like to compare an axis tank with an allied tank (say a Tiger and a Sherman), but I could also compare two tanks from the same side. I am wondering if anybody out there can recommend books or websites (preferably books) that have specific information on a tank’s main weapon. Specifically I am looking for muzzle velocity and the shell mass. I know that CM has muzzle velocity in the detailed descriptions of the units, but I really don’t want to use a video game as a reference (although I will if I have to; that is going to make an interesting bibliography entry!). Shell mass might be harder to come by, so I would entertain using a well supported, educated guess. :confused: Thanks for the help! Mick Link to comment Share on other sites More sharing options...
Bullethead Posted March 5, 2002 Share Posted March 5, 2002 Talk to a rabid armor penetration grog here who goes by the handle of rexford. Do a search for any of his posts--he's member #4402. When you find one, get his email address off his profile. Link to comment Share on other sites More sharing options...
IronChef4 Posted March 5, 2002 Share Posted March 5, 2002 sounds cool. . .post parts of your paper on the forum once its done. . .i would be interested in reading it. Link to comment Share on other sites More sharing options...
aka_tom_w Posted March 5, 2002 Share Posted March 5, 2002 Originally posted by steelmtn: I am in college and taking physics (calculus based) where the professor wants the students to write a 2-4-page paper on any physics subject. I am kicking around the idea of comparing the effective kill distance between two WWII tanks. I have to write my own equations based on the knowledge I have gained so far in the class and as much real data that I can gather. I would like to compare an axis tank with an allied tank (say a Tiger and a Sherman), but I could also compare two tanks from the same side. I am wondering if anybody out there can recommend books or websites (preferably books) that have specific information on a tank’s main weapon. Specifically I am looking for muzzle velocity and the shell mass. I know that CM has muzzle velocity in the detailed descriptions of the units, but I really don’t want to use a video game as a reference (although I will if I have to; that is going to make an interesting bibliography entry!). Shell mass might be harder to come by, so I would entertain using a well supported, educated guess. :confused: Thanks for the help! MickThis is VERY do-able Search the forum for Rexford's posts Search also for the word "penetration" there is a le-maire (sp??) equation around here somewhere that is the so called "root" or basis of all armour penetration calculations in CMBO We would be interested in reading your paper Have you done any other research yet? Keep us up to date. -tom w Link to comment Share on other sites More sharing options...
c3k Posted March 5, 2002 Share Posted March 5, 2002 Hi, As a comparison to WWII era tanks and guns, the book "King of the Killing Field"(?) is about the M-1 Abrams. Some facts off the top of my head: muzzle velocity of ~5,000 feet/sec. Penetrator mass of ~10kg. Of course, its armor is classified. Don't know about ANY Iraqi kills in Desert Storm. Well, that's the modern stuff. Ken Link to comment Share on other sites More sharing options...
Madmatt Posted March 5, 2002 Share Posted March 5, 2002 A good book with overviews on anti-tank weapons, history and employement is Ian Hoggs "Tank Killing". I picked up a copy used for about 9 bucks and I found it to be an excellent read. It goes into detail about Personal AT-Weapons, Tank Destroyers, ATGM's, AT-Guns, Mines, AT Helos and Tanks themselves. Madmatt [ March 05, 2002, 10:26 AM: Message edited by: Madmatt ] Link to comment Share on other sites More sharing options...
markshot Posted March 5, 2002 Share Posted March 5, 2002 Another good place to pose tank related questions is over at the: www.steelbeasts.com forum. Also, I believe that there is a tank network site out there for real world tankers. The Steel Beast forums have a lot of real world tankers. Originally posted by steelmtn: I am in college and taking physics (calculus based) where the professor wants the students to write a 2-4-page paper on any physics subject. I am kicking around the idea of comparing the effective kill distance between two WWII tanks. I have to write my own equations based on the knowledge I have gained so far in the class and as much real data that I can gather. I would like to compare an axis tank with an allied tank (say a Tiger and a Sherman), but I could also compare two tanks from the same side. I am wondering if anybody out there can recommend books or websites (preferably books) that have specific information on a tank’s main weapon. Specifically I am looking for muzzle velocity and the shell mass. I know that CM has muzzle velocity in the detailed descriptions of the units, but I really don’t want to use a video game as a reference (although I will if I have to; that is going to make an interesting bibliography entry!). Shell mass might be harder to come by, so I would entertain using a well supported, educated guess. :confused: Thanks for the help! Mick Link to comment Share on other sites More sharing options...
Paul T. Gardner Posted March 6, 2002 Share Posted March 6, 2002 steelmtn, I've pulled together a few links for you. Bit of a mish mash, and not totally focused, but in the right direction... http://salts.britwar.co.uk/salt7.htm http://www.onlineconversion.com/armor.htm http://www.isl.tm.fr/en/scientif/pages/d1/d1_e.html http://www.warships1.com/W-Nathan/M79apdoc.htm Rgds Link to comment Share on other sites More sharing options...
steelmtn Posted March 6, 2002 Author Share Posted March 6, 2002 Thanks for the help. I will try to check out all the suggestions. The paper is due April 4 and I will post it to this site after I get it back, which will probably take a week or so. I won't waste your time with it if I get a bad grade. :mad: Thanks again for the help and keep the suggestions coming, I will be checking back here often. Hopefully I will get a chance to play more CM instead of just writing about it. Mick Link to comment Share on other sites More sharing options...
rexford Posted March 7, 2002 Share Posted March 7, 2002 You can e-mail me directly and I will provide all the data and equations you will need. Lorrin (Rexford) Bird Link to comment Share on other sites More sharing options...
Mattias Posted March 7, 2002 Share Posted March 7, 2002 Now there's an offer you can't refuse! Hope you have, at least, an adsl connection Steel M. Link to comment Share on other sites More sharing options...
Larsen Posted March 7, 2002 Share Posted March 7, 2002 The question that you raised is devided into two parts. One is the question about the kinetic energy that the shell posses at the moment of impact. That consists of the kinetic energy of forward motion and kinetic energy of shell rotation around it central axis. This is not hard to calculate. With a good approximation you can write down MV^2/2 + Iw^2/2 where M is the mass of the shell, V - is the velocity upon impact, I - the moment of inertia and w is the angular velocity of shell rotation around its central axis. The second question is how armor behaves when it is hit with something that posses that much energy as a gun shell. The answer is given by a theory of composite materials. Basically the steel behaves as steel only in the first moment on the impact. Then if the the shell posses enough energy stell melts around the point of impact (first order phase transformation - one can calculate how much energy is required to melt certain amount of steel regarding the process as adiabatic) and start flowing as a viscous liquid. How much it flows, how far the shell core will be to travel in such a media is not a simple question to answer. Look for the physics books on composite materials to get some formulas. Larsen Link to comment Share on other sites More sharing options...
Sgt. Beavis Posted March 7, 2002 Share Posted March 7, 2002 edited. [ March 07, 2002, 01:09 AM: Message edited by: Sgt. Beavis ] Link to comment Share on other sites More sharing options...
Captain Wacky Posted March 7, 2002 Share Posted March 7, 2002 You could compare a Sherman round's penetration of two specific tanks & deal specifically with the effectiveness of thick vertical armor versus thinner sloped armor. Of course, we all know which one is better, but your classmates probably don't. As an added bonus, if you pick the Tiger and Panther as your test subjects, you can print out all sorts of cool photos Link to comment Share on other sites More sharing options...
steelmtn Posted May 30, 2002 Author Share Posted May 30, 2002 A thousand apologies, oh patient ones! This paper was turned in on April 4 and I didn’t want to post it here until I got my grade back on it. The professor paid way more attention to his research instead of grading papers so I never got the paper back. He posted all the grades the class got on their papers on the web during finals week. I am happy to say I got 11 out of 10 points on this paper. That’s not a misprint, 11 out of 10. I owe Mr. Lorrin Rexford Bird a ton of thanks for all the data and information he sent me. Likewise, thanks to all of you who send info for this paper. Now for the disclaimer: I am pretty sure I used the DeMarre equation incorrectly for this paper. I got results that look pretty good and support what we all expect from a Tiger vs. Sherman fight, but I have a nagging suspicion that I didn’t work it quite right. Unfortunately, my grunt work on the equations are hand written and were added at the end of the paper, which the professor still has. I could try and get the paper back from my professor this summer and post it here if any of you are interested in me doing that. I am not sure if my professor will be around, so I may have to wait until the fall to get the paper back. I could try to rework the equations before then if all of you absolutely must see the math involved. This paper really needed to be longer to do this subject justice. It was really out of my league to try and write this paper, but I did the best I could and the result was satisfactory. However, I do realize that there probably are some mistakes within this paper. Given more time, more resources, and more knowledge (this paper was written half way through the ONLY physics class I have ever had) I am sure the result would be better. Please feel free to comment, this subject is fascinating and I want to know more about it. Mick Link to comment Share on other sites More sharing options...
steelmtn Posted May 30, 2002 Author Share Posted May 30, 2002 Sherman vs. Tiger: Not a Fair Fight Battles in World War II were characterized by tank warfare. For the United States and the United Kingdom the workhorse of battlefield was the M4A3 Sherman. It was the most used tank for the D-Day landing at Normandy on June 6, 1944 (Ford 92) and it continued to be relied on until Germany was defeated. However, nothing was more demoralizing to allied tank crews than to see a German Panzerkampfwagen VI Tiger. One Sherman crewman from the Normandy invasion made this report: We sighted two Tiger tanks of the Das Reich division at a range of 600 yards. We fired four shells which all bounced off. The Tigers subsequently turned around and headed straight for us. We pulled back after losing six Shermans. One of our Firefly tanks (a Sherman variant) managed to score a direct hit on the left flank of one of Tigers before it too was destroyed by the surviving Tiger. We saw the crew escape from the crippled Tiger and climb onto its comrade before the tank retreated. There were no survivors from our tanks, which simply burst into flames (Tiger Phobia). Encounters like this were fairly frequent in WWII and it presents an interesting physics question: what is the likelihood that an armor piercing shell fired from each tank will penetrate the hull of its counterpart? On the WWII battlefield the tank served a dual purpose. Tanks followed their WWI inspired role to support infantry by taking out machine gun nests and breaking through fortified enemy positions. World War II had a very dynamic front that changed rapidly compared to WWI and tank warfare was largely responsible. The tank’s other main mission was to destroy or disable the enemy’s tanks. In WWII most tanks were outfitted with a main gun mounted on a turret. Frequently these guns could fire a variety of rounds including high explosive, hollow charge, tungsten core, smoke, and armor piercing rounds. The high explosive rounds would generate shell fragments on impact and were primarily used on infantry, vehicles with light armor, and other soft targets. Hollow charge rounds, sometimes referred to as High Explosive Anti-Tank (HEAT) rounds, focused a thin stream of hot gas against the armor plate, which would melt a hole through the armor. Tungsten core rounds used the high-density, shatter-resistant properties of tungsten to improve their armor piercing capabilities. Smoke projectiles produced a thick screen of white smoke to temporally reduce an enemy’s ability to see. An armor piercing (AP) shell usually has no explosive charge and used kinetic energy to try to punch though armor (Moylan 58). The armor piercing shell was the easiest to produce and was therefore used most frequently against enemy tanks. To determine if a shell will penetrate homogeneous armor is a very involved process. There is a direct relation between the diameter of the projectile and the thickness of the armor. Metal armor will act differently when the metal is thin compared to a projectile’s diameter, or when both are of comparable thickness, or when the armor is very thick. Another consideration is the Brinell Hardness Number of the projectile which would help determine if the shell shatters on impact instead of using its kinetic energy to punch through the armor (Okun). The tensile strength of the armor usually needs to be considered as well. Although these conditions do factor into whether or not a shell will penetrate armor, it is out of the scope of this paper. In this specific example, how well the Tiger and Sherman tanks resist an armor piercing shell fired at each other will be investigated. This process requires three steps. First, the kinetic energy of the shell will be determined. Second, the equivalent vertical thickness for sloped armor will be calculated. Finally, by using the DaMarre equation the amount of kinetic energy needed to penetrate the armor will be found. For this example the following assumptions are made to apply to the physics equations used. The calculations are found at the end of this paper. (1) Air resistance against the shell is ignored. This will be equivalent to having the tanks fire at point blank range. (2) Both tanks are sitting on level ground so the shell hits the upper front portion of the hull while traveling parallel to the ground. This means there will be no increase or decrease in the slope of the armor. (3) The Sherman fires a 75mm (diameter) AP shell with a mass of 6.79kg and a muzzle velocity of 619m/s. The armor on the upper front hull is 50.8mm at a 56-degree slope (Bird). (4) The Tiger fires an 88mm AP shell with a mass of 10kg and a muzzle velocity of 780m/s. The armor on the upper front hull is 102mm with a 10-degree angle (Bird). During WWII, the U.S. Navy did a study to estimate the amount of work needed to expand an infinitely small hole in steel plate to the diameter of a projectile. Their findings were consistent with a formula known as the DeMarre equation. This equation basically predicts the amount of energy a projectile requires to penetrate a certain thickness of armor striking it perpendicular. If the energy is too low, the projectile will not penetrate and will probably ricochet away. However, this equation does not factor in the slope of the armor. Many of the tanks in WWII had sloped the frontal armor to increase the chance of a ricochet. To work with the DeMarre equation, the armor at a slope must be converted into an equivalent vertical thickness. The DeMarre equation states the amount of energy created by a shell’s mass times its velocity squared is equal to a constant, “K”, multiplied by the ratio of the armor thickness over the diameter of the shell raised to 1.4, times the cube of the shell diameter. In other words: mass * velocity^2 = K * (thickness/diameter)^1.4 * diameter^3. The mass is in kilograms, velocity is in meters-per-second, and thickness and diameter are in millimeters (these values are not converted to meters.). The constant K was determined by finding the thickest perpendicular plate width the gun could penetrate 50 percent of the time fired at point blank range (maximum velocity and, therefore, maximum kinetic energy). The value for K is 3.70kg/m*s^2 for the Tiger and 4.70kg/m*s^2 for the Sherman (Bird). This constant can then be used to determine if a shell has enough kinetic energy to penetrate any thickness of armor. Sloped armor performs better than perpendicular armor because it takes more kinetic energy for projectile to punch through the sloped armor. Effective thickness of sloped armor is found by determining a slope multiplier. The thickness of the armor over the diameter of the shell is the T/D ratio. Match this number with the slope of the armor in figures 1 and 2 to give you the slope multiplier. This number is multiplied with the actual armor thickness and the result is the effective armor thickness. For the Tiger, the armor thickness is 102mm and the shell diameter from the Sherman is 75mm. Therefore the T/D ratio is 1.36. The Tiger’s armor is sloped at 10-degrees so the slope multiplier is 1.03. Therefore, the Tiger’s 102mm armor sloped at 10-degrees performs the same as vertical 105mm armor. The Sherman’s armor thickness is 50.8mm and the shell from the Tiger is 88mm, so the T/D ratio is .58. Using a slope of 56-degrees results in a slope multiplier of 2.32. Therefore, the Sherman’s 50.8mm armor sloped at 56-degrees performs the same as vertical 118mm armor. Now all the information is available to perform the calculations. To relate the DeMarre equation to the kinetic energy equation, two divides both sides of the equation. The AP shell fired from a Sherman tank has the kinetic energy of 1,300,831J. The amount of kinetic energy that is required to defeat the Tiger’s upper hull is 1,587,928J. This shell does not penetrate the hull of the German tank and ricochets away. The AP shell fired from the Tiger has the kinetic energy of 3,042,000J. The amount of energy that is required to defeat the Sherman’s upper hull is 1,900,986J. This shot penetrates the Sherman tank easily and probably knocks it out for the rest of battle. The Allies did not beat the German tanks with superior tactics; they beat them with sheer numbers. Allied tank commanders would frequently send five Shermans or an equivalent medium tank against one Tiger and expect to lose four of the Shermans. Hopefully one of the Shermans would get in a flanking shot against the Tiger where the armor was 80mm thick with no vertical slope (Tiger Technical). The Americans built about 50,000 Shermans, one of the many types of tanks used by the Allies (Ford 51). This is approximately twice the total number of tanks Germany had altogether. The Soviet Union also built about 40,000 T-34 tanks during the war (Ford 63). It was with these armored fighting vehicles that Germany was defeated in WWII. Works Cited Bird, Lorrin Rexford. Email interview. 15 Mar. 2002. Bird, Lorrin Rexford and Robert D. Livingston. WWII Ballistics: Armor and Gunnery. New York: Overmatch Press, 2001. Dyer, D.P. “Armor Profiles: Medium Tank M4A3 ‘Sherman’.” 24 Mar. 2002 <http://www.onwar.com/tanks/usa/profiles/fpm4a3.htm>. Ford, Roger. The World’s Great Tanks From 1916 to the Present Day. Hong Kong: Barnes & Noble, Inc., 1997. Moylan, Charles, and Steve Grammont. Combat Mission: Beyond Overlord. Big Time Software, Inc., 1997. Okun, Nathan. “Homogeneous Armor Penetration Computer Program M97APCLC.” 24 Mar. 2002 <http://www.warships1.com/W-Nathan/M79apdoc.htm>. “Tiger Phobia.” 27 Mar. 2002 <http://www.panzer-vi.fsnet.co.uk/tigerphobia.html>. “Tiger Technical Data.” 24 Mar. 2002 <http://www.panzer-vi.fsnet.co.uk/specifications.html>. Link to comment Share on other sites More sharing options...
Black Five Posted May 30, 2002 Share Posted May 30, 2002 Hey you stole my signature. Well then again you know who said it so I'll have to change mine Link to comment Share on other sites More sharing options...
steelmtn Posted May 30, 2002 Author Share Posted May 30, 2002 It's a great quote! Feel free to continue to use it to spread the wisdom. BTW - have you ever played the Avalon Hill board game called Diplomacy? That was my first love with military strategy games and the inspiration for using this signature. Mick Link to comment Share on other sites More sharing options...
Renaud Posted May 30, 2002 Share Posted May 30, 2002 Ken, "Don't know about ANY Iraqi kills in Desert Storm. " At least 1 M1A1 was destroyed by a T72 during Desert Storm. I think it was a 1st AD tank which had just bypassed a T72 at night. The T72 was stone cold (smart commander there) so no one saw it in the thermals. Got in 2 point blank range shots. The first penetrated the rear engine vent covers and blew out the power pack. The 2nd penetrated the rear turret and detonated all the turret ammo. The blow-out panels saved the crew. Per-SOP, they did not have the ammo door propped or they would have all been killed. Note that this was 2 point blank 125mm shots in the rear and the crew survived! Pretty impressive. I think the hatches were closed as well and the NBC system was probably on, which doubtless helped. The T72 was then spotted and destroyed by following M1's. I suspect that we had a few more tank losses, I did see at least one pic of a another tank crew being choppered out after their vehicle was knocked out. M1's are vulnerable to front hits at certain obvious but small weak spots. For the most part we did not give the Iraqi gunners time to do more than snap off 1 or 2 wild shots. Ren Link to comment Share on other sites More sharing options...
Trooper Posted May 31, 2002 Share Posted May 31, 2002 If memory serves, there were two M1s knocked out by enemy fire. One was the T-72 you mentioned, the other was a BMP which got a shot into the engine. Only one Abrams tanker was killed in combat, it was a TC who was unbuttoned when he directed a HEAT round into a BMP at about 20 meters. On the mathematics front, go to http://www.tank-net.org and go to the Armour Scientific Forum. I almost never go in there, it's far too technical for me.. NTM [ May 31, 2002, 04:22 AM: Message edited by: Trooper ] Link to comment Share on other sites More sharing options...
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