Jump to content
Please support this forum by joining the SH Patreon ×
Sturgeon's House

N-L-M

Forum Nobility
  • Posts

    732
  • Joined

  • Last visited

  • Days Won

    19

Posts posted by N-L-M

  1. Looks like a very high sink rate. The aircraft is fully flared on landing, so either the approach angle was too steep or the plane thought it was several hundred meters higher up than it really was. The bounce is characeristic of extremely heavy landings- the undercarriage can't damp it all out, and the pneumatic springs shove the airframe right back into the air. It looks like the impact may have been violent enough to fully compress the springs to their mechanical stops, at which point the shock gets transferred directly to the aircraft. The shock bending loads on the structure trying to accelerate the heavy nose cantilever from "steep descent" to "rebound" exceeded the load limit and the airframe broke where the bending moment causes maximal stress- at the base of the cantilever.

  2. 5 hours ago, Mighty_Zuk said:

    I am guessing it might be because of the size of the powerpack.

    The Israeli Centurions at that point used the same power pack as the M60 and M48 (with minor fittings differences), so that's a no.

  3. 6 minutes ago, alanch90 said:

    for which case they already have conceptual work done for Strv 2000.

    Strv 2000 is entirely obsolete in the current year and would basically have to be restarted almost from scratch.

    Remember, Strv 2000 was a project in the late 1980s, and it's been over 30 years since then. Other than broad layout and concepts (like modular armor), and any ballistic tests conducted at the time, everything involved in that project is obsolete.

  4. So I was on a certain Discord server and the topic of reactive armor came up. I ended up writing a rather long post about why RHAe is a fundamentally flawed method of measuring the effectiveness of ERA, vs other models (such as a fractional model ( % reduction in penetration), even those do not entirely accurately reflect reality).

    I post it here unedited for your critique, do your worst (which is of course your best).

     

    Rhae

    The problem is that with that approach your measured "RHAe" is just a rephrasing of the measured residual penetration with no further info processing applied, and is only useful as far as your individual measurements are. And when your armor's effectiveness is affected by the projectile's penetrating ability, well, the "armor equivalency" value gets dependent on the projectiles characteristics in the specific case and not in any way in a generalized manner, which defeats the whole point of having a unit of measure in the first place.
    You see, nobody uses plain old 220BHN RHA any more for anything other than weapons testing. But it's still useful as a reference for armor materials within the limitations that the defeat mechanisms are similar- typically, clean penetration into semi-infinite targets. This allows you to compare different solutions within the same class.
    For example, if against a certain threat class 500bhn steel penetrated cleanly has a RHAe of 2 vs 220BHN steel at a given obliquity, you know this to hold true across that class and definitely for individual projectile designs.
    As an example, If I know that an AP round will go through 100mm 220BHN RHA at 1km, I know it will also go through 50mm of the 500 BHN stuff.
    Likewise, if that same projectile fired at the same velocity goes through 110mm 220 at 0.5km, at that range itll go through 55mm of the high hard stuff at the closer range.
    And I know that if I scale the projectile design up such that it now defeats 120mm 220, it'll also defeat 60mm 500.
    So far, so good.
    But now I try to apply the same logic to a reactive plate.
    A dart round rated at 100mm 220 at 0.5km is fired at the ERA and achieves only 50mm of residual penetration. From this I conclude that the ERA has a "RHAe" of 50 against this projectile design.
    I then proceed to fire it at 1.5km, where its penetration is only 40mm 220.
    By the above logic, I should expect it to never pass the ERA. But it will, and the residual penetration will shred all the poor innocent 1mm witness plates.
    Now lets take the same projectile and scale it up, so it can go through 120mm RHA at 0.5km and fire it at the ERA. By the above logic, I'd expect it to achieve 120mm (rated) - 50mm (ERA RHAe) =70mm. In practice, the reactive armor will chew it up such that it penetrates notably less backing as a residual effect.
    And for a SC example, a given single shaped charge 100mm in diameter will go through say 600mm 220 BHN at optimal standoff. A reactive layer cuts that down to 100mm. From here I get a "RHAe" of 500mm.
    Shaped charge penetration is known to scale linearly with size for a given design at similar non-dimensional standoffs. So we take a 0.8 scale ie, 80mm) version of the last warhead. It'll go through 480mm 220 BHN steel. Applying the equivalency logic, we'd expect the residual penetration to not exist, as the armor equivalency is greater than the rated penetration. In practice, it's going to have residual penetration, on the order of 80mm. Big error there from a difference of a mere 20% in scale.
    See the problem? Trying to measure RHAe for reactives is problematic because their method of operation is fundamentally different. Not only is it inconsistent within a class, it's inconsistent for a single given projectile design as well! If you want to start plotting "RHAe of Kontakt-5 vs M829A1 as a function of range" as well as the usual obliquity testing, you will very quicky find that in practice you are to within a fairly tight confidence interval merely drawing a rescaled and slightly offset ballistic chart for the M829A1 itself, which if you don't think is silly (considering you then need to do this for all known projectiles, even of similar designs), well then have fun I guess. The data you compile by this method is mostly useless at that point.
    Having different fitted models for different threat types and even design styles is legitimate. But when you have to individually fit each independent penetrator with a model of its own *which is also dependent on the particular state of the projectile at impact, well clearly you’re doing something wrong.

  5. 2 minutes ago, SPARTAN ARMED said:

    Why they scrap the old tanks and didnt make robotic ! the chinese try on with t55 tanks.

    Because when you make a robotic vehicle you do it for one of 2 main reasons:

    1. As a technical demonstrator

    2. As a useful vehicle

    In the first case, using old tanks is silly because theyre crazy expensive to run. You can run a M113 or MT-LB if you want a tracked vehicle, or a fancy ATV if you don't, all of which are waaaay cheaper to run than a tank.

    For the second case, you want a useful vehicle even in the face of enemy fire. If you don't want to stop enemy AT fire, your choices are the same as the above, plus the option of a purpose built compact vehicle. If you do want to stop enemy AT fire, the old tanks aren't up to it and need at the very least to be uparmored; and by being significantly larger than they need to be (as computers are smaller than crewmembers), this ends up being significantly larger heavier and more expensive when compared to a purpose-built vehicle.

     

    In either case, the old tanks aren't really worth it.

  6. 13 hours ago, Belesarius said:

    Whats with the blue plastic?

     

    Those are garbage bags.

    MGs do not like being exposed to the elements for any length of time, they get all wet and therefore rusty and all the oil runs off and shit. Wrap them in a garbage bag and duct tape it shut and you have a fairly effective quick and disposable environmental shield.

  7. That's a Sparky vid. You can tell by the distinctive spastic red and yellow text overlaid with no consideration of contrast over background images.

    Sparky and his opinions belong in the trash.

    The most powerful tank gun actually fielded on serially produced tanks was probably the US M58 120mm gun. 

  8. 19 minutes ago, Mighty_Zuk said:

    Heck, I don't even know how to protect APS from small arms fire

    Hint- it's retardedly easy.

    You have a radar, which detects incoming rounds.

    And a shutter, which can stop them.

    You use the radar to cue the shutter.

    You can even have 2 different kinds- the shutters on the radars and optics close only during the calculated time of impact, and otherwise stay open. The shutters on the interceptors stay closed except for launch. 

    Easy, your APS is now resistant to anything smaller than what your shutters are rated for. You could do this for 14.5mm KE if you really wanted but the servos would get a bit fat. 35mm KETF cannot compete.

×
×
  • Create New...