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N-L-M

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Everything posted by N-L-M

  1. N-L-M
  2. N-L-M
    Per "surviving the ride", the 6x6 with 2 front axles was intended to solve the problem of losing all mobility when the front wheel hit a landmine, by just having an extra sacrificial pair up front. This extra pair of wheels however led to substantial yaw stability issues and was not successful.
  3. N-L-M
    They dont allow hotlinking, but they will open in a new tab.
  4. N-L-M
    Gonna have to ask you all to cool your jets and discuss things in a civilized manner. It's easy to get excited about things on the internet, please take it easy, especially in the current year.
  5. N-L-M
    Having very recently finished a design cycle, I can now offer insight into how I do things. The first thing I do is look at the requirements, and the available options (whether limited by name or simply similar in performance), and try to figure out a first order approximation of what it is I'm hoping to get done. It's usually at this point that I sketch out the design in pencil and make a list of design features I intend to include in the design - this typically helps solidify the concept in my mind, as well as making sure I don't miss anything major along the way. I set myself certain design goals to guide myself along the way at this point, as they shape to an extent how I want the design to end up. It's also at this stage that I tend to obsessively google ballistic charts, gun blueprints, and internal pics of relevant vehicles, for cribbing the designs off later. This approach is very "front heavy", in that it requires you to have a very good image of what you want to get done in your mind before you ever really touch the CAD software, but it does mean that other than minor tweaks, you only CAD once. The Norman, Fox, .224 Rapier, and now BT-5-76/43 were all substantially first shots. Some details were ironed out as the design progressed (typically, precise dimensions are initially guessed and then adjusted as needed), but the concept, down to, say, the location of the extra periscope on the roof, was sketched out on day 0. This approach also means modelling is easier, as you are focused on carrying out the decisions of the design committee (you) and not making the decisions themselves. As the design progresses, the day 0 first order approximations may turn out to be incorrect. The BT-5-76/43 was initially supposed to only have thick side-skirts along the fighting compartment, with thinner ones to the rear, but then I realized I had a sufficient mass budget to allow me to go wild, so I did. As you go, it's important to keep whatever goals you set for yourself in mind. With a sufficiently blank slate, it's easy to get lost and start designing spaceships with All The Features TM, when you should be focusing on core capabilities. For the Norman, the core was a tank on par with late Centurions; for the BT-5-76/43, the core was "I do not want to touch the driveline or the turret ring in the process of improving this vehicle". Some features (like vision cupolas) are basically free improvements if you remember to include them; others (like fuckoff big guns) require substantial tradeoffs which must be viewed in the context of their effect on the bottom line of the design goal. I tend to start from the turret, then the hull, then the armament, then systems, and finally suspensions and the like. The wonders of parametric modelling mean you can make a rough hull shape, design components to fit, and then rejigger the hull as required by the systems. There's no good replacement for pencil sketches and barely legible scribbles on paper, in terms of focusing one's design intent into practice. CAD is just a way of translating that scribble into something others can understand too.
  6. N-L-M
    It's gonna be a tight squeeze, no two ways about it. BT-7A managed to squeeze in a 76mm gun IRL, so it's not impossible. Hopefully the loader assist means the gunner needs to move around quite a bit less in combat, and the cupola does give the commander a little more breathing space.
  7. N-L-M
    It's nothing more than a couple gravity feeds and a couple manual spring return ratchets where you yank the handle of the type you want to pull it far enough to drop it into the rammer tray. Really nothing complex at all.
  8. N-L-M
    At -10 degrees depression, the gun only just hits the turret roof at full recoil but the tube clips through. Limiting depression to -5 degrees solves that problem. Perhaps ejecting not with a tube but with a T-62 style roof hatch (only on the front of the turret) would allow the full 10 degrees of depression. Also apparently elevation is +15 not +10 as previously stated. I dun goofed there. The tube requires a bit of a mantlet expansion but nothing special. The latter. At -5 degrees they're aligned, as the barrel elevates and the breech drops theres a bit of a drop from the height of the hopper feed to the ramming tray, but it isn't very far to go.
  9. N-L-M
    Flame cutting and riveting are sufficient for the armor fabrication, though welding is preferred of course. All the rest is either stolen, simple, or unmodified from the existing tank.
  10. N-L-M
    Carro Armato BT-5-76/43 General specs: Weight: 15t nominal, 16 t loaded. Length, gun forwards: 7m Width: 2.3 m Height: 2.3 m to turret roof Crew: Commander, Gunner/loader, Driver. Armament: 45mm, 75mm or 76mm gun, roof mounted HMG, coax MG, and grenade projectors. Mobility: Slightly reduced from BT-5 to cope with added weight, but still excellent. 25 HP/T at 16 tons. Survivability: Excellent against 37mm, acceptable vs 75mm, borderline against 57mm, none against 76mm. Detailed description:
  11. N-L-M
    The front add on armor has a hinged door linked to the existing one in the UFP (not modeled), and the upper door works as it did.
  12. N-L-M
    Not only that, I found a way to make it hide the existing gun in the model which I can't edit! (protip: it's shown at -2 deg elevation)
  13. N-L-M
    That more or less concludes the modelling work for my submission.
  14. N-L-M
    It's happening
  15. N-L-M
    Still very much a work in progress, but seeing as I haven't posted all that much in this thread, I thought I'd post it as-is. The add-on armor is still very rough, and is missing the turret ring armor. You'd be surprised how well armored a BT-5 can get if you put your mind to it.
  16. N-L-M
    OK so, road trip is over. Reading from my (almost illegible) notes I wrote a couple weeks back: 1. Of the available tanks, the BT-5 is, IMO, the only reasonable choice. 1.1. The T-28 cannot be reasonably made a real opponent to the Sherman and is rare, with a spares issue just waiting to happen. 1.2. The various French light tanks and T-26 are disasters on tracks, with no armor, no real option to improve armament, and very poor automotives (low power to weight and low speed suspension). 1.3. Of the guns available, only the 7.62 cm PaK 39(r) can reliably kill a Sherman with AP, and that is neither in service nor will the Germans willingly part with them or their ammo in large quantities; Also, the case is that of the PaK 40, which cannot fit into any of these turrets anyway. Therefore any Sherman killing must require HEAT or some other means of defeating the tank without getting through the armor directly. 2. Why the BT-5 is a good choice 2.1. Most of what made the BT-5 a poor tank IRL are "soft" factors which can be fixed fairly cheaply and quickly, if the goal isn't to go up against Shermans. 2.2. The BT-5 is uniquely suited to being weighted down, owing to the frankly ludicrously over-specced drivetrain. 2.3. The added weight of the BT-7 vs the -5 did not by any source I've found adversely affect reliability, and again as far as I can tell the suspension was not heavily modified. 2.4. For going up against light tanks, the 45mm is quite good and perhaps does not require replacement at all, for a low-end option. 2.5. The sheer number taken intact by the Germans, as well as the large number of spares salvageable from disabled ones, allows a large and capable fleet. 3. Proposed BT-5 upgrade: 3.1. Mobility This is in fact a bit of a downgrade, to cope with the increased weight to be mentioned later. 3.1.1. Increasing the preload of the springs by spacers in the spring wells, to retain ground clearance. 3.1.2. Installing volute bump stops on first and last road wheel stations to prevent over-stressing springs, at cost of some of the very generous travel. 3.1.3. Installing drive wheels with 5 rather than 6 drive nubs to raise final drive ratio - prevents over-stressing drivetrain at the cost of reduced speed at all gears. Even at a 5:6 reduced speed, the BT-5 is silly fast. All in all, very easy to do, requires light welding work to install bump stops and requires fabricating new drive wheels - not hard at all. Should allow a weight of around 15T vs the original 12T or so. Ground pressure in Italian terrain is also not that big of an issue, and the BT-5 has silly low MMP ground pressure anyway thanks to the massive track pitch. ... and just like that, my posting time for the day has run out. What will N-L-M do with 3 tons of extra weight on a BT-5? Tune in next time for another exciting episode of... pimp my tank!
  17. N-L-M
    Got jumped IRL by a work trip. I'll be back home next weekend, I hope.
  18. N-L-M
    Encountered slight issues with using free internet 3d surface-based models in solid-based CAD, will require more work before I have something showable.
  19. N-L-M
    Alrighty I have a fairly clear battle plan, I'll probably knock it out this weekend. I have... Several silly ideas and a few moderately sensible ones.
  20. N-L-M
    @Toxn How about ZiS-2s?
  21. N-L-M
    Done some basic "what do" thinking. The problem, as posed, is extremely difficult to solve in a satisfactory manner, largely thanks to the (excellently picked) very poor selection of cast-off vehicles upon which to base designs. And when the reference point is a Sherman, even just a 75mm one, that's quite the tough nut to crack and quite a lot of gun to stop.
  22. N-L-M
    https://www.opgal.com/products/lsa-kit/ Google image search is your friend. Please learn to post.
  23. N-L-M
    In the Challenger 2, much like the Chieftain and Challenger 1, the ammo in the hull is stowed all over the place, but the 3 main bins of vertical propellant charges, if removed, provide adequate space for storing unitary ammo horizontally. Likewise, the frontal hull propellant racks, when removed, provide some more space there, though that likely requires rejiggering of the rest of the internal components there, as the unitary 120 is much longer. Perhaps that area wasn't touched, and the 15 are stowed horizontally where the 3 main bins were, nose to nose from 2 sides. Such an arrangement would also make them fairly accessible to the loader, somewhat making up for the low overall load.
  24. N-L-M
    You appear to be using Google Translate very, very poorly. That combined with the subject matter of this thread is enough to make one very suspicious.
  25. N-L-M
    You still have the dismount squad to help you out, and if you have the commander but count him as a dismount, well he's also available for maintenance and operating the vehicle when on board.
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