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Stephan

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About Stephan

  • Birthday 01/10/1978

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    Clausthal, Germany
  • Interests
    Tanks, mountainbikes, tanks, computers and tanks of course

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  1. Actually, the term I had been looking for is fracture toughness. What would I have given for the Wikipedia of today back then...
  2. Because in a world of compromise, some won't?
  3. A quick check makes your math seem correct. I love guesstimation and the Rossby number is my friend. The Rossby number basically is the ratio of inertial to Coriolis forces, where a small Rossby number indicates a large influence of Coriolis forces and vice versa. The Rossby number calculates as R=U/(f©*L), with U beeing a systems velocity, L the length scale of system movement and f© the Coriolis parameter. Depending on lattitude, f© ranges from 0 to 1.5*10^(-4), it is safe to assume as 10^(-4) here. So, in the example of the 25mm round traveling at 1500m/s over a distance of 2000m we can approximate as follows: velocity and length of movement are of the same order of magnitude, leaving us with R=1/10^(-4)=10000. On the other hand, the good old Paris gun fired its round at about 1500m/s (at least at the muzzle...) over a distance of some 120000m, the length of the movement is two orders of magnitude greater than the velocity, which gives R=100. For good measure, some other values to put things into perspective: in a tornado, you will find a Rossby number of about 10^3, the effect of Coriolis forces is negligible there; in contrast an atmospheric system is strongly affected by Coriolis forces, here, Rossby numbers of 10 and less prevail. So in essence, for cases of direct fire, where system velocity and lenght of movement are on the same order of magnitude, you can neglect the Coriolis effect, on the other hand if you were to shell Paris...
  4. Stephan

    Puma

    Well, I was forced to carry the $"%&! thing at some point during a course at PzGrenBtl 72 and I thought I remembered there was a mounting bracket in the MARDER labeled Erdziellafette. On the latter, it is possible that I mix that up with the FUCHS.
  5. Stephan

    Puma

    I have to say that I am not up to speed with current planning of the squad organisation. Usually, the dismount element would operate as a coherent team using the IFV as the base of fire team. However, just as you say, it really depends on mission and terrain. I.e. take an AT mission in a forrest: the IFVs are left behind, each dismount team forms into an AT section of 2-3 men with 2 PzFsts, the rest acts as an overwatch section around the machinegunner. Similarly for a final assault in the offense: Before the final assault starts, the machinegunner and an assistant (maybe also with an AG36) take a position to support the rest of the team during break in with high volume fire in conjunction with the IFV. I am not so sure what the impact of all those new weapons and stuff of the IdZ will mean for the dismounts, especially the MG4. Saying it in the positive form, the MG4 will reinforce the role of the IFV as the base of fire and underline coherence of the dismount team. Or in other words, loosing the MG3 with its tripod means loosing an effective base of fire option. Also, please keep in mind, that as a former armor NCO, I only have limited training on the tactics of pedestrians .
  6. Stephan

    Puma

    At first one may be surprised and looking at the main measurements of the PUMA and MARDER, one would expect that there must be a lot more room on the inside of the PUMA. However, that is were the much improved protection of the PUMA over most if not all other IFVs takes its toll. The Panzergrenadiers had wanted at least 8 dismounts, but that just was not possible. BTW, the dismount strength of the PUMA actually is 7, the squad leader is supposed to dismount, too. Vehicle command then goes to the mounted team leader/ gunner.
  7. Stephan

    Puma

    No, it is a joint career path. Everyone starts in the common basic training, after that, gunners and drivers are seperated for specialist training in their fields. Prospective leaders will usually start in the dismount component and then move upwards into the positions of dismount team leader, squad leader (vehicle commander!), half-platoon leader and platoon leader. Note that the vehicle commander is superior to the dismount team leader and that in the Bundeswehr, two of the three platoon leaders in the company are NCO positions. The platoon, wether mounted or dismounted, always acts as a unit*. The Panzergrenadiers put emphasis on the distinction, that they always are a Panzergrenadier platoon and that the dismount element does not become an infantry platoon when dismounted - it is the dismount element! In the same spirit, a Panzergrenadier squad is not only the dismounts, but the dismounts and IFV. *Yes, there are exceptions. E.g. in the current mission environment, it is not uncommon to have a half-platoon or even single squad supporting a patrol package. The decision to dismount is at the discretion of the platoon commander (or the squad leader). The dismount team leader then takes over as vehicle commander. The decision depends on where the platoon commander sees the main effort of his mission. Actually no. The deployment mode of the ATGM (wether the MILAN or SPIKE) depends on the terrain. In open terrain mobile warfare, mounted employment will be more of the norm. On the other hand, in difficult, interrupted terrain, dismounted use is rather more favorable. A dismounted, well hidden missile team is a much more difficult target to counterfire at than a >30t IFV. Also, when dismounted, you actually can use both at the same time much more easily: the missile from one or two positions and cannon fire from the IFVs from other positions. The PzFst 3 is a standard weapon for the squad, IIRC there are three (that is, three launchers and six rounds of ammunition) per squad.
  8. For some more pictures and text on hypervelocity impact, visit the projects page of the Fraunhofer Ernst Mach Institute: Fraunhofer Ernst Mach Institute, Impact Physics, at the bottom of the page. The Spacecraft E-Box section has a nice picture of a sandwich impacted by an Al-Sphere.
  9. My battalion had, besides medics and other aid, three ARVs at the Eschede train wreck.
  10. Now that you say it, I do not recall seeing anything like a horn or rearview mirrors on the M1 when I had a short tour, not that I did pay much attention to such side issues. As USAREUR vehicles are not licensed in Germany, they do not need to fullfill the regulations anyway, so... The germanised version of US vehicles (M48, M109, M113,...) had mirrors and horns, though. The flashing "police" lights johnr refers to are required to mark oversized vehicles. Though, as they are yellow, they are a mere warning light and in no way imply the same rights as the blue police lights.
  11. At least for german vehicles, the german road vehicle licensing regulations require that a vehicle has a horn. So, yes, the Leopard 2 and all other german made armored vehicles do have a horn. I would not be surprised if it was the same for most other countries.
  12. Just to get all these fuel issues straight: Diesel actually is rather a blend of different distillate fractions from the middle distillate, in contrast to gasoline or kerosene. More specifically, diesel is a mix of kerosene and light, medium and heavy fuel oil. The exact composition can vary from lot to lot, depending on the raw oil composition and availability of the different fractions due to market fluctuations. The kerosene content is increased during the winter season to lower the cloud point. Before 1996 (in the EU, IIRC 2006 in the US), the quality of diesel was not well controlled, due to very wide specifications - especially in the US. This bad quality was one of the considerations for the US to switch to the much better specified JP-8/ F-34 (one obviously more important one being logistics), which was available cheaper than high quality diesel.* The various JPs are based on the civilian jet fuels with various additives to achieve specific military requirements. E.g. the base for JP-8/ F-34 is Jet-A1/ JP-1A/ F-35, with the additives S-1745 (Fuel System Icing Inhibitor), S-1747 (Corrosion Inhibitor/ Lubricity Improver), a static dissipator and antioxidants. JP-4 was based on Jet-B, a wide cut fuel with a high gasoline content. JP-5/ F-44 is a high flashpoint safety fuel for naval (aviation) applications. JP-6 was an XB-70 specific developement, an improvement on JP-5 with e.g. a decreased freezing point. JP-7 was (is?) a high supersonic fuel, specifically for the SR-71, with improved thermal stability and increased flashpoint. Coming back to JP-8, there are several complications when using it for land applications. Many will have heard of the reduced flashpoint compared to diesel (38°C to 56°C) and the reduced specific energy compared to diesel (~10%, so, using kerosene, or increasing the kerosene content in diesel will reduce power, not increase it). Additionally, as has been mentioned, kerosene can solve diesel deposits in the fuel system. This will also affect turbine engines that previously ran on diesel for a longer time. The solved deposits will clog the fuel filter. For a while after switching from diesel to kerosene, the fuel filter should be cleaned with petroleum F-58 to prevent problems. The biggest issue of JP-8 comes with modern diesel engines. The Cetan number of JP-8 is about 10-20% lower than that for diesel, which leads to problems with high compression engines, the comparatively low lubricity of JP-8 is a problem with common-rail injection systems. Thus a multi functional additive (S-1750) needs to be added to JP-8/ F-34 to create F-63, however, F-63 shall not be used in (aircraft) turbine engines, which makes the single fuel concept a bit questionable. * E.g. for Germany, the situation was quite the opposite. Just when JP-8 was finally specified and available NATO-wide, closely specified, high qualitiy diesel became the norm on the civilian market and thus was available cheaply, so the Bundeswehr choose to keep diesel F-54 as the standard fuel for peace operations in Germany (another consideration was the introduction of more modern engines with the above mentioned complications).
  13. Honestly, I believe it is more of a question of the situation you are in. Imagine a hasty defense, you are immobilized. Do you wait for enemy forces to overroll you, most likely getting you and your tank captured? SOP at least calls for the tank being abandoned and destroyed. In contrast, during a fast attack, the (retreating) enemy will likely concentrate his fire on the still advancing troops. So you can rather safely stay in the tank and wait for recovery.
  14. Death before dismount!
  15. If, maybe, could. Sure. Thing is, the armor systems in both tanks seem to be a bit more complex than that. The M1 uses DU in some of its armor, which in principle is pretty dense and thus rather effective. Question remains how much DU and in what configuration. My point is after all, that your approach doesn't give a conclusive result whether the M1 turret side offers better protection compared to the Leopard 2. Look for some of Paul Laskowskis calculations, those roughly go into the right direction. These calculations require rather carefull weight/ volume analysis and a quite intimate knowledge on available technologies. T-72 more roomy, sure.I had the pleasure to look at the mentioned tanks a bit more closely. Oh, I do see that point! I am constantly criticising MRAPs, the IVECO LMV and other vehicles of that kind. They use automotive parts as sacrificial mass which is just lightly protected or even unprotected. However I have to concede, that protecting these parts would unduly increase the system weight - you would get somewhere into the region of a Piranha or Boxer and the like, if you want protected mobility. Those latter just are to big to go into certain areas and without doubt are a lot more expensive. So in the case of these MRAP-like vehicles, many armies decided that the principal crew protection was more important and worth the risk that in the case of an ambush, the immobilised vehicle may fall easy prey to a dedicated attacker.
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