Comment on Estonia is digging a 40 km trench to stop Russian tanks — and 600 bunkers are next
Warl0k3@lemmy.world 15 hours agoCorrect: AFVs aren’t tanks, but tanks are AFVs. Using the supercategory in this case is just a nod to actual tanks being pretty rare on a modern battlefield vs. the vast number of tracked armored vehicles.
And also yeah, no argument about gun elevation. Which is why you just go fast over a trench like this, and rely on it being < 1/2 the length of your vehicle (ex: the T-72 has a ground support length of around 9m for this roughly 4m trench) for added stability while crossing. Which totally ignores that you’d only get to where a 90° elevation would be relevant if you go so slow you’re pointing directly down into the trench, which wouldn’t happen if you impacted the angled far wall (which is why real tank ditches are shaped like the dunning kruger graph or the trench in the vid I linked - a sharp vertical wall to prevent climbing combined with an angled ramp to direct the bulk of the tank downwards before it’s feasible for the gap to be jumped)
Keep in mind that tanks initially existed for the sole reason of crossing tanks like this. While warfare has evolved and tanks no longer have WWI / Warhammer style gigantic climbing tracks, the basic use of a tank as an obstacle-crossing fire support vehicle has not changed.
Madison420@lemmy.world 13 hours ago
crust.piefed.social/comment/151494
It’s specifically a question about a tank.
No you don’t, you might fast and turn the turret around like the video shows but you’re not going to plow into a dirt wall and foul your barrel if you don’t have to.
I really shouldn’t have to draw a picture to show you if your front end goes 35° hull down just to stay level with level terrain you’d need 55° up elevation. In this case there’s another ridge that’s probably 40° so add 40 to 55 and you get? Anyone? Anyone ? 95°! And we just agreed no MBT has 90° up elevation so the only possible thing you could be proposing would be that tank crews are going to en masse heave themselves into a wall they know their barrel will impact and likely foul in rather then turn the turret and cross to the other side where you can then use your tracks to move the dirt in the hill back into the pit so it’s whole again.
I’d say that’s absurd but maybe in this administration bugs bunny operates a no holds barred tank division but I dunno I guess I don’t keep up with the news enough.
Warl0k3@lemmy.world 12 hours ago
Aight so that was sad enough I figured I’d do a couple physical sims just to answer the question definitively:
turns out a T72 would need +35° of elevation to clear this if you approached at 1kph
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But at +14° elevation, it'll just barely clip the top at 30kph
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And only needs to be going ~46.02kph to clear the berm
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But to cross at 30mph, you’d only need to rotate the barrel ~20° off center-line to clear the berm (which if Warthunder is to be believed (hehe), will take 5/8^ths^ of a second to return to axial - this is as close as I could get to the actual figure but it’s probably closer to a full second, I couldn’t find acceleration curves for the T-72 turret traversal (go figure)).
So you’re right, most likely a T-72 crew would have to rotate the turret some to clear this berm unless they’re going flat-out across that field, which is possible for them to achieve but the offroad speed of the T-72 isn’t super reliably reported (again go figure) so lets just go with you’re right.
And with that side topic settled, back to my point: this ditch ain’t going to force an AFV to slow down. Like at all.
Disclosures:
I used the absolute shortest value for ground support length which is only 5.5m, used the common 106" ditch crossing value for ease instead of calculating it custom as soil dynamics sucks to define, used the most generous estimate I could for ditch dimensions (4m wide w/ 90° slopes) and just traced the outline of a T72 where I couldn’t find specific dimensions in the manual I’ll pretend I have sitting on my desk but which I just googled around to find, and I also just totally ignored ground compression for the same reason (but eyeballing it, it should roughly even out)
Madison420@lemmy.world 11 hours ago
Correct me if I’m wrong but you’ve just admitted you were wrong.
No when people say tank they mean MBT, if you drive a Bradley and call it a tank Abraham’s crews will straight up laugh at you. The phrase you used doesn’t matter, the question is will that actually stop a tank. My response was no but it will slow them, your answer was “Nuh uh!”. Now you’ve proved visually by yourself that you are wrong and probably shouldn’t have “uhm actually” your way into the conversation.
Warl0k3@lemmy.world 10 hours ago
My god, you’ve broken my secret code.
I’ve quite exhaustively shown that yes, at some speeds a T-72 would impact the berm without rotating the turret. I’m not… I literally drew you diagrams dude, I don’t think I could be more explicit about how this works out. But If they don’t slow down this won’t be the case. They will clear it without having to rotate the turret. They also, as you’ve claimed, will not have to turn the turret “away from the berm”. I couldn’t be more clear than this without a lego set and a mallet. I was provisionally wrong about the turret, unless you take it in the context of my earlier thing about not slowing down, where I would correct.
But I don’t really care enough, so have the win about the turret. It’s my little gift to you.
The issue is more complicated than you seem to present it, and I did my best to clarify that. Also, yes, I already acknowledged how the misclassification of things as MBTs is the source of popular Tanker drinking games. It’s common enough there’s a billion articles like this out there, clarifying things. It’s not a phantom phenomenon, are you really trying to turn that into the issue to litigate while glossing over the slow-down-an-attack aspects now?