Question at very bottom if you want to skip my rambling.

One of my favourite tanks ever is the T34/76c.
She was THE innovation of tank technology, way ahead of everyone else.
The British and French both had tanks with sloped rounded armour, but especially in the British case, where their tanks after the Matilda seemed to go back to the square box foolishness as if they really never did appreciate the benefits of sloped armour and it was just a fluke on their part.
The French unfortunately didn't have time to show their minds on tank design though the 1 man turret and short gun was a definate faux-pas.

But the T34/76 was the Corvette of tanks.
Thicker armour than most, but sloped and molded, light, with aluminum engine parts,
unlike the Sherman, low silouhette, harder to spot, smaller target
fast, and unlike the KV tanks, didn't need to gear down to gear up again
long ranged, wide tracks to spread out weight distribution allowing it to go on terrain other tanks would get bogged down into
effective 75mm at gun while most of the world was still stuck with half as big, shorter, less effective guns
economical, numerous share parts with other mass produced tanks
even T70s
years ahead of its time
just a beauty

(the T34/85 was of course much more powerful, 3 man turret, 2 way radios etc, but also taller, bigger target and I just love the 76 'sleekness' if you will.)

I was watching a tank documentary on the Science and Learning Channel where they let an old Ukrainian veteran take a rebuilt T34/85 out for some runs.

He, through the translator, told a funny story.
He said that there was a legend about the sloped armour, that it wasn't planned for from the start based upon the physics of a 45 slope doubling the effective thickness of a perfectly horizontal line measurement,
but instead it was the 'logical' step when instructed to decrease a tank's total weight(therefore cost too)
thus to do so, a straight line from nose to hull top used up less steel than one or two step sections as in the PzIIIs.

That the benefit of superior protection was in fact accidental!

That would be a hoot and proof of how much in science and engineering is discovered by accident.

Looking for a cure for Alpha and accidentally running across a better treatment for Beta.

Any similar 'legends' like that out there?

Research into the effects of sloping armour plate was first conducted in the 1930s by the French SOMUA, and by the Soviet tank design team of the Kharkov Locomotive Factory.

http://en.wikipedia.org/wiki/Sloped_armour

Unfortunately could not find the SOMUA results.

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It was a good tank,no doubt. I believe the U.S. had first crack at the Christtie suspension but passed on it. I'm not sure why sloped armor was studied so much. It dates back to US Civil war era[1870's] to "deflect" incoming cannon.

Exactly, in fact the Greeks even before the Romans were aware of the 'mathematics' of the principle.

Amazing how hard 'wisdom' is to get into some organization mind-sets though.

But it was a funny story we tourists enjoyed and I could very well see it happening that way in whatever country thought about it. But the way he told the story, no-one was thinking 'mathematically' nor of ancient Greece. Though, nevermind, i was going to talk how the Greeks supposedly stumbled across it while trying the different 'deflection' theory for shield walls.

Still, love these neat stories of how stuff came about.

Maybe the rake served two purposes. I woulda thought they might have angled also it to shift some of the weight to the center, instead having it all hang over the end of the car, making it less likely to tip forward, just enough to derail all or part of the rear bogie. In my description, the front is at the muzzle and rear at the breach of the cannon.

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Best Regards,
JW

A couple of unrelated to military history ones I had a hand in were:

Growing SiAlON (Silicon Aluminum Oxygen Nitrogen) whisker reinforcements for advanced ceramics. I worked at a company that gave me a sketch design for a furnace to grow Silicon Carbide powder in a continious production process. I built a working prototype from the sketch.
As a side result that was completely unintended, it made the longest (at least 8"+ perfect SiAlON whiskers ever produced! Better than Sandia Labs did in a special reactor for just that purpose and at a fraction of the cost. It also made OK SiC.
The other was making a reactor for Carbon 60. Made the first one from basically junk lying around the building. Power supply was an arc welder on sale at Sears....really... Best part I saw that POS on a NOVA episode on Carbon 60 and one the lab techs later made by scaling up my design and using eight (8!) of the same arc welders! I was ROFLMAO seeing that!

Correct there, all sorts of arguments for sloping armor. The primary argument against is internal design. Folks want to have losts of room for machinery, crew, and ammo storage. The result of this is usually vertical side armor, and poorly sloped areas on the front.

Naval architects had compiled a large body of data on armor & AP ammo from experiments and experince since the mid 19th Century. The use of this for designing tank armor seems to have been less than perfect.

LOL. You guys still looking at that picture. It could've been for any number of reasons.
If it were straight up, it would be quite the wind-catcher being pulled along the tracks. It looks like it gives the crew more protection this way being how cannon fire mostly came from above traveling in an arc.
Picture the V shaped snowplow blade on the locomotive,pushing snow off to the sides and more aerodynamic[though not a concern of tanks.]

In some respects there is something to be said for the boxy vehicle versus the heavily sloped designs like the T 34. In a boxy vehicle the armor thickness is generally directly related to its ability to withstand a hit while in a sloped armored configuration this becomes more problematic.
The problem here is that the armor while sloped and therefore theoretically thicker than if it were vertical in presentation to a round is still only the original thickness in terms of some other aspects of penetration. For example the T 34's glacis is only 50 to 60 mm thick depending on model. This means larger tank rounds impacting it theoretically must penetrate about 90 to 110 mm of armor. But, a larger shot fired from say a Tiger also will have an impulsive load based solely on its mass (eg weight) that can simply shatter the 50mm plate which is too thin on its own to withstand that load. In this situation it doesn't matter if the plate is sloped. It did no good as the plate itself was too thin to withstand the impact. This is sometimes refered to as "overmatch."
Therefore, a designer really has to work against several different effects in putting protection on an AFV. Slope alone is definitely no panacia. As a note, German tankers were instructed to try and approach enemy antitank weapons at an angle to them which in effect gave their vertical armor a theoretical slope in a horizontal rather than a vertical plane achieveing the same effect! Something to think about.

There is always a way to eliminate any advantage built. As Russian tank designs got harder to take out, US munitions experts started looking at artillery round that used heat seeking guidance systems to target the weak armor over the engine. The life span of any design is relatively low in combat.

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Lord, let me be the person my dog thinks I am.

Measure counter measure
sight-smoke
radar-chaff
machine gun-tank
submarine-sonar
communication-code
T-34-TIGER!

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"Danger Will Robinson!"

Tiger - Breakdown!

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"Wars cannot be fought with dream stuff" - Sir Percy Hobart.

TIGER -no steel-no fuel-no ammo-no transport-no bridges-no crews-no training-no repairs-no recovery, no no no no I don't want one no more.

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"Danger Will Robinson!"