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    • By OnlySlightlyCrazy
      The full title of this work is "Weaponeering - Conventional Weapon System Effectiveness" by Morris Driels, who teaches at the USN Postgraduate School, and the cover of the edition I have in hand can be seen below.


       
      The book aims to "describe and quantify the methods commonly used to predict the probably of successfully attacking ground targets using air-launched or ground-launched weapons", including "the various methodologies utilized in operational products used widely in the [US military]." Essentially, this boils down to a series of statistical methods to calculate Pk and Ph for various weapons and engagements. 

      The author gave the book to my mother, who was a coworker of his at the time, and is of the opinion that Driels is not as smart as he perceives himself to be. But, hey, it's worth a review for friends.

      I will unfortunately be quite busy in the next few days, but I have enough spare time tonight to begin a small review of a chapter. I aim to eventually get a full review of the piece done.

      Our dear friends @Collimatrix and @N-L-M requested specifically chapter 15 covering mines, and chapter 16 covering target acquisition.

      Chapter 15
      Mines

      The mine section covers both land mines and sea mines, and is split roughly in twain along these lines.

      The land mine section begins with roughly a page of technical description of AT vs AP, M-Kill vs K-Kill, and lists common US FAmily of SCatterably Mines (FASCAM) systems. The section includes decent representative diagrams. The chapter then proceeds to discuss the specification and planning of minefields, beginning with the mean effective diameter of a mine. Driels discusses a simplified minefield method based on mine density, and then a detailed method.

      The simplified method expresses the effectiveness of the minefield as a density value. Diels derives for the release of unitary mines from aircraft

      NMines = Fractional coverage in range * fractional coverage in deflection * number of mines released per pass * reliability * number of passes

      and for cluster type

      NMines = FRange * FDefl * NDispensers * Reliability dispenser * NMines per Dispenser * Reliability Submunition * number of passes

      and then exploits the evident geometry to express the Area and Frontal densities. Most useful is the table of suggested minefield densities for Area Denial Artillery Munition and Remote Anti-Armor Mine System, giving the Area and Linear densities required to Disrupt, Turn, Fix, and Block an opponent. 


      Whereas the simplistic method expresses effectiveness as a density, the detailed model views the targets and mines individually, assuming the targets are driving directly through the minefield perpendicular to the width and that there is only one casualty and no sympathetic detonations per detonation. The model computes the expected number of targets destroyed by the minefield, beginning with the Mean Effective Diameter and the PEncounter based on distance from the mine. 

      Driels derives the number of mines encountered which will be encountered, not avoided, and will engage the target. I can't be arsed to type the equations in full, so here you go.



      The section concludes with an example calculation using the detailed mine method. Overall, this shows the strengths and weaknesses of the book fairly well - it is a reasonable derivation of open-source statistical methods for predicting Pk and Ph and the number of sorties required, but US-specific and limited in scope and depth. 

      The treatment of Sea Mines  begins by describing the various types and uses of said mines, importantly noting that they have both defensive and offensive uses, and that the presence of the threat of mines is equally important as the actual sinking which occurs. There are three classifications of sea mines, contact, influence, and controlled.

      Shallow water mines are treated trivially, considering them equivalent to land mines with Blast Diameter in the place of MED, and assuming that the mines cannot be avoided.

      Deep water mines are approached in a similar manner, with the desire to determine the number of mines needed to achieve the required probability of damage, and planning missions from there. Two features of sea mines must be considered, however - mine actuation by passing of the target, and mine damage to the target. The probability of activation is, unfortunately, dependent on the depth of the mine and distance, forming a series of stacked bowls as below.


      The mean value of PActivation is the statistical expectation of the curve. Because I don't feel like screencapping another equation, the Width of Seaway where an actuation can occur is qualitatively merely the area under the actuation curve calculated for a specific mine and target combo.

      The damage function is also of interest - because we require the mine to both actuate and damage the target, this limits our earlier area under the curve to that area integrated to the limits of the damage function. The selection of mine sensitivity plays a very large role in the effectiveness of our mines. A high setting will lead to many more actuations than damages, which can be indicated by the ratio of the actuation area and the damage area from earlier. Setting the actuation distance equal to the damage distance means that every actuation causes damage, but the probability of actuation is only around 42%. The compromise which selects some Areadamage / Areaactuation of around .8 to .93 is generally preferred. This gives us several useful terms -
      PA+D = Reliability * Areadamage / Widthminefield . The probability that the first ship to transit a minefield is referred to as the threat, or
      Threat T = 1 - (1 - PA+D)^NMines = 1 - (1 - Reliability * Areadamage / Widthminefield ) which can obviously be solved for NMines to get the desired number of mines for a desired threat level.

      Anti-submarine mines are an interesting subset of deep sea mines, as they turn the problem from two-dimensions to three. Driels accounts for this by replacing the mine damage width with the mine damage area, to no one's surprise. Driels claims that the probability of actuation and damage is 

      PA/D =  Damage Area / (Width * Depth of minefield). Despite my initial confusion, the reliability term safely reappears in the threat definition below.

      T = 1 - (1 - (Reliability * Area damage)/(Width * Depth of minefield))^NMines, with a solution for number of mines for given threat level fairly easily taken out as before.

      Lastly, there is a summary of topics for each chapter, though unfortunately they are qualitative descriptions. Including the final derived equations in this part would be a major benefit, but is overlooked. Ah well. They are quite good for review or refreshing the material.

      As before, this is a relatively interesting if shallow engagement with the statistical methods to calculate Pk and Ph and the number of sorties required. Going more into detail regarding selecting Threat values or common (unclass) parameters would be interesting, but is lacking. Assuming I don't slack off tomorrow, I should have most or all of the Target Acquisition chapter covered.
    • By A_Mysterious_Stranger
      Been delayed with stuff but I've wanted to post this.  Actually I'm surprised I've never seen anything in detail about this before, because it's an interesting topic.  (IF there IS a topic on this I apologize and it can be merged there.)  
       
      ETC tech is something you probably hear about if you hang out on tank, military or gun forums.  Especially if Railguns or coilguns are mentioned.  Or 'next step' in gun design like 140-152mm guns.  There's lots of information out there if you look and you discover just how diverse it can be.
       
      I'm sure most people are aware that Wikipedia has a article on ETC tech and as far as Wiki articles go it's decent.  But the person who worked on it in the past also wrote an article on ETC for the Nationstates draft room.  It's old but still good.  So despite the origins it's still useful (the writer was also a member on Tanknet IIRC.  Take that as you will.) 
       
      In Jane's Technology of Tanks, Ogorkiewicz also commented about ETC:
       
       
      Ogorkiewicz also discusses the concept in Tanks: 100 years of evolution:
       
       
      One realization from this is ET/ETC technology is quite diverse and can be confusing.  One of the better sources covering that concerned Rheinmetall research into a German 120-140mm (courtesy of Wayback because the original source fell to link rot):
       
      Link to image of Rheinmetall ETC classifcations
       
       
      On the amateur experime which discusses ET/ETC stuff in detail too.   If you prefer the more 'hype' side of things, ETC was also tied to the Future Combat Systems - a link some people may recognize:
       
       
      As you can see, ETC is evolutionary  not revolutionary like EM guns.  It takes existing technology and builds on it:  You can settle for improving propellant ignition (minimizing electrical cost) or add electricity to boost performance (up to the 'pure' ETC idea)   You can also utilize the technology on Liquid propellant and possibly even Light Gas guns - it stacks quite nicely with other ideas.  You can even use it with a bigger caliber.  This is part of the ETC charm.
       
      Further information on ETC stuff can be found here:
       
      AN END-TO-END MODEL OF AN ELECTROTHERMAL CHEMICAL GUN
       
      Electro-Thermal Chemical Gun  Technology  Study
       
      Both of these are articles I like, but there's more stuff:
       
      Electrothermal-Chemical (ETC) Technology Weaponization Issues
       
      Electrothermal-Chemical Gun Systems  Utilizing Novel Electric Solid Propellants
       
      And of course DTIC is a wealth of ETC stuff:
       
      (direct pdf links):
      Overview on the  German R&D Programs on ETC  Gun Technologies for Main Battletank  Weaponization
       
      ELECTROTHERMAL-CHEMICAL PROPULSION AND PERFORMANCE  LIMITS FOR THE 120-MM, M256  CANNON
       
      And some dtic links to ETC stuff that requires download:
       
      Electrothermal-Chemical (ETC) Propulsion with High Loading Density Charges.
       
      Ballistic Analysis of Electrothermal-Chemical (ETC) Propellant.
       
      Trade-Offs in Performance Enhancement of Solid-Propellant (SP) Electrothermal-Chemical Guns.
       
      Sturgeon's House user sevich also posted a link to a useful ETC document off ditc  here
       
    • By A_Mysterious_Stranger
      I've noticed there is no repository for ballistic science documents the way there is for the Mechanized or the infantry forums (for example) so I decided to fix this. 
       
      My first offering is dtic stuff from the past on some weird and novel ways to extend the L/D ratios of spin stabilized projectiles.   I originally learned about this from someone I was having a discussion with years back and hunting lead me to one of those discussions about bringing back the battleships on navweaps discussion boards where one of the posters (Zenmastur) laid out his master plan for Battleship resurrection.  Which included the aforementioned 'higher than 6:1 L/D ratio spin stabilized projectiles'.    It took awhile to hunt down but I eventually found some of the original documents that focused on novel projectile shapes (for a large improvement) and non-conical boat tails (for a much smaller improvement)   
       
      Obviously this went nowhere insofar as I am aware, and I suspect they had drawbacks nobody addressed (like most do) but it's an interesting thing to look at anyhow.   Much of this is the work of one Anders S. Platou, who seems to be as prolific as the RAVEN guy. 
       
      AN IMPROVED PROJECTILE BOATTAIL
       
       
      AN IMPROVED PROJECTILE BOATTAIL. PART II.
       

      Improving the Flight Performance of Projectiles 
       
       
      MUZZLE-BLAST-INDUCED TRAJECTORY PERTURBATION OF NONCONICAL AND CONICAL BOATTAIL PROJECTILES
       
      THE EFFECT OF VARIOUS BOATTAIL SHAPES ON BASE PRESSURE AND OTHER AERODYNAMIC CHARACTERISTICS OF A 7-CALIBER LONG BODY OF REVOLUTION AT M = 1.70
       
       
       
      YAWSONDE FLIGHTS OF 155MM NON-CONICAL BOATTAIL PROJECTILES AND THE 155MM M549 PROJECTILE AT TONOPAH TEST RANGE-OCTOBER 1977
       
       

      YAWSONDE FLIGHTS OF 155MM NON-CONICAL BOATTAIL PROJECTILE-B CONFIGURATIONS AT TONOPAH TEST RANGE--MARCH 1978
       
       
      AEROBALLISTICS OF 9ORKSCRE1 PROJECTILES (12 page document)

       
       
       
      AEROBALLISTICS OF CORKSCREW PROJECTILES (36 page document)
       

       
    • By LostCosmonaut
      Have you ever wanted a game that is like KSP for boats, but with terrible graphics? Rule the Waves  might be for you!
       
      Design boats, some of which are probably going to be terrible!
       

       

       

       

       
       
      Play as great naval powers from the early 20th century, such as:
       
      US UK Germany France Russia Japan Austria-Hungary (?) Italy (??) Spain (???) The Confederacy (????) Sweet battle graphics!
       


       
      Diplomacy!
       

       

       
       
       
      Here's a copy of the manual: http://www.navalwarfare.net/files/SAI/RTW_MANUAL.pdf
       
      Have at it.
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