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About CaptnAndy

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    Master Chief Petty Officer
  • Birthday 07/10/1944
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    Folsom, CA
  • Interests
    Author/Publisher of BB-39, a Greatest Generation Novel: on Amazon.com.

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  1. CaptnAndy

    Real World Gun Fire Control

    These fire control compensations were present in almost all USN WW2 main battery mechanical analog fire control computers.
  2. Someone asked me to repeat this posting from a year or so ago .... AIMING A NAVY CANNON ACCURATELY – Introduction to Fire Control By Bill Berry Our ship has just loaded a bunch of dumb (unguided) projectiles for the gun mount, left port, and has been confronted with a bad guy that (in the words of the late John Wayne) needs shooting. We have the bad guy in our sights. 1. Bang! We missed. Why? Well, we pointed the gun exactly where the bad guy was, but suddenly gravity took over and pulled the projectile down and into the water, well short of the target. We've been trying to get Congress to repeal the law of gravity, but like everything else, they don't do anything! OK, we'll compensate for gravity and aim the gun up in accordance with the range setting from the latest ballistics tables. But there’s a little problem. Those tables imply we know the shooting range to the target. How do we get that? Well, in the early days before 1910, we identified the target, measured his mast height and used a stadimeter to give us range. Then the bad guys got wise to that and changed mast heights. So we shifted to a rangefinder, where we optically split someone’s eyeballs out several feet and calibrated a mirror for convergence or, later, stereoscopic measurement. The bad guys then tried different camouflage schemes. One obvious issue was that if you couldn’t see the target, you couldn’t get its range, such as the target using a smokescreen or sneaking up at night. Then the British, followed by the Americans, came up with radar, which gave us an accurate range. Now we can use the ballistics tables, which some distant mathematician came up with in a lab somewhere. We crank the gun’s elevation up a tad so the projectile can finally reach the vicinity of the target. 2. Bang! We missed. Why? The smoke from the first firing obscured the gunner's sight. OK, we'll use a second gunsight and place it on a remote gun director, which will send the firing angles down to the gun mount. Then we'll aim again and shoot. 3. Bang! We missed. Why? The remote gun director was not in line with the gun. It needs to have had a battery alinement performed on it so that its sights and those of the gun itself are in complete parallel when looking at a distant star. All angles are referenced from a common Ownship Centerline, so that each director and each weapon describe the same relative bearing and elevation angles: 196° bearing means the same regardless if it is a launcher, a search radar, a director, a sonar, a gyro, a pelorus, or whatever on the ship. Further, if the gun director’s platform is on a different geometric plane than the gun, it’s also a guaranteed miss. Either the gun and director need to be machined to exactly the same plane, or a roller path correction computation needs to be added to the firing solution. 4. Bang! We missed. Why? There's this dumb math thing known as parallax between elements. Since the director is not on the gun mount anymore, we have a triangle between the gun, the director and the target. Parallax is inversely proportional to range. For the distant star we used during battery alinement, it made no difference, but the target isn't at infinity, it is much closer. As range decreases, the differences become much bigger. So we correct for that and shoot again. 5. Bang! We missed. Why? As the gun was being aimed, our ship rolled, pitched and yawed, and threw off our aim. So we add a stable element (a gyroscope) to bring the gun into stabilization so the ship can roll, pitch and yaw all it wants. 6. Bang! We missed. Why? Our ship moved in the water. It wasn't going real fast, but by the time the firing key was pressed, and the round actually left the barrel, it was several milliseconds. So we have to add a correction for not only our angular movement (roll, pitch, yaw), but our linear movement (speed). And we have to be smart about this as well, because there is a difference between COURSE and HEADING. COURSE is the direction of travel in the water, a movement vector. HEADING is the angle the ship's bow has with respect to North. We have a cruise liner in San Diego with a HEADING of 090° into the pier, but its COURSE is 270°. How is this possible? Well, its engines are in reverse as it backs away from the pier. So we look at all the linear velocities our ship makes, and add these into the solution, and shoot again. 7. Bang! We missed. Why? Our target was so UNREASONABLE. It decided that it didn't want to stay in a fixed place and let us shoot at it. It, too, has movement, and by the time the projectile got to where the target was, it wasn't there anymore. So we have to solve for its course and speed, and predict where it will be when the projectile lands. This requires some intricate calculations that constantly change over time, and further, the target tries to keep us guessing as to where he's going to go next. For convenience, we subtract ownship pitch and roll (deck tilt), converting target position to a horizontal plane. Then we enter (and refine) target courses and speeds. Once we are happy, we resume fire with pitch and roll tailored to the gun (known as trunnion tilt) added to the gun orders. 8. Bang! We missed. Why? It turns out that the wind was blowing our projectile off course as it headed toward the target. Well, up on our yardarms we have anemometers that tell us which way the wind is blowing across our deck, so let's add these corrections into our solution. 9. Bang! We missed. Why? The problem is that once the projectile leaves the gun, the wind across the deck has no further impact, it is at the mercy of winds aloft that could be blowing in an entirely different direction. That's why a gunner needs to read the weather report. Better still, a local weather balloon can determine which way the wind is blowing aloft. And winds aloft aren’t constant, either, wind gusts can mess up the most refined solutions. 10. Bang! We missed. Why? Well, the wind isn't the only atmospheric issue out there. There's one called Air Density (kind of like barometric pressure) that can speed up or slow down the projectile from its more-or-less specified velocity. 11. Bang! We missed. Why? You would like to think that all projectiles have the same weight. But if your gun thinks it is firing a 70 pound projectile and it only weighs 69 pounds, there's going to be an error. 12. Bang! We missed. Why? The propellant charge of a projectile is very temperature sensitive. If it was stored at 66° Fahrenheit, but you thought it was 61°, the projectile will leave the gun at a different speed. That's why the gunners' mates take temperature reports for their magazines. 13. Bang! We missed. Why? The gun barrel, over time, becomes wider and wider, and this affects the speed of a projectile leaving the ship. That can be verified with a measurement known as projectile seating distance. Projectile weight, propellant temperature and barrel wear all affect a quantity known as Initial Velocity (IV). A good gunnery team will calculate and compensate for IV well before the first shot is fired. Needless to say, if the gun barrel gets too wide, accuracy suffers. Newer ships also have a velocimeter on the gun mount that determines the IV and applies it to the next shot. 14. Bang! We missed. Why? Believe it or not, the earth turned. If you fire a gun to the north, for example, the projectile becomes an inertial object while the earth (and everything on it) continues its rotation. It differs by latitude, so latitude compensation needs to be included in the solution. 15. Bang! We missed. Why? When the projectile left the gun, it was spin-stabilized by the lands and grooves inside the barrel. As it goes out in space, it tends to drift one way or another (depending upon what was inside the barrel). Usually this is a known value and a function of distance to be traveled. So we correct for it. Another issue is a quantity known as gun jump. The gun, when firing, jerks a little as the projectile heads down the barrel. This also affects aiming, but it is generally predictable. 16. Bang! We missed. Why? That UNREASONABLE target decided that it was no longer fun to be shot at, and deployed countermeasures. He could dazzle us with electro-optic brilliance, or jam our radars, or put out decoys, or whatever it would take to spoil our aim. Of course, we just might be ready to employ counter-countermeasures, but at least we got close enough to scare him on our last shot. 17. Bang! We missed. Why? Now it is up to the human element. We can see where our projectiles have been landing, and we have employed a technique known as Arbitrary Corrections to Hit (ACTH) based upon the last several gun shoots. So now it is up to a method of spotting, adding corrections manually to bring the shell splashes closer to the target or have our target realize that it is no longer really healthy for him to hang around here. 18. Bang! We missed. Why? One of our vital pieces of equipment wasn’t properly maintained, and the overpressure from the gun shoot finally shook loose a critical cable. So we rush a maintenance team up to fix it. 19. Bang! We finally hit the target, but there wasn't an explosion. Why? We didn't calculate time of flight correctly and send these data to the projectile immediately prior to firing. This value, known as Fuze Time, is cranked in at the gun mount and tells the projectile that it must go for nn seconds before the fuze is armed. With an armed fuze, depending on the projectile type, we can either get a proximity detonation or a delayed detonation due to point contact. But if the projectile doesn’t have the correct fuze or fuze time, you might get a little hole in the target but that’s just about it. 20. There’s an old Marine Corps adage that needs to be repeated here. “If the target is within range, so are YOU.” If it took you this long to think of all those things that could go wrong, the target just isn’t going to let you shoot at him and do nothing. So the duties of a Fire Controlman are to anticipate these issues before they occur, and NOT think that some magical computer is going to do all your work for you. And remember that the best planned maintenance for any gun system is to shoot it often, so that when the REAL bad guy shows up, you’ll know it works. I recommend firing each gun whenever the ship leaves port, even if the target is nothing but a balloon. This briefly describes some of the variables used in a surface to surface Naval gunnery engagement, and when I left the Navy there were some 78 of these items, many of them constantly changing. For an antiaircraft firing, the number increases as a third dimension (altitude or height, with its changes) enters the picture. And missiles? Well, big surprise. They have most of the same problems, plus a few of their own. They have to know who is controlling them, know which way is up, be aimed properly, anticipate and correct for all these variables, and then leave with enough instructions so they can find the bad guy. If any of these isn’t done correctly, we have a wonderful fireworks show which might impress some people, but probably not the target. This was copied from a fb post by Dave Berry from a US NAVY FIRE CONTROL fb group. As a former Fire Control sailor 61-65, I thought it would be interesting to share here.
  3. CaptnAndy

    So many ebooks

    I have to put in a plug for my Naval Action books, BB-39, After The Days Of Infamy, Resurrection World, the Eden Project, and Last Emergence. The last 3 listed are SF books that feature some Naval Action. You can find them all on Amazon under A.G. Kimbrough. https://kdp.amazon.com/en_US/bookshelf?ref_=kdp_RP_PUB_savepub&language=en_US Or, on my web site at: https://www.agkbooksandblog.com/
  4. CaptnAndy

    New Mexico AP

    Several in our clan have noticed over pen on BBs, including a Monty overpenning a Yammy on a broadside salvo just above the midships waterline. It sounds like the DD overpen "fix: was applied across all ships.
  5. Thanks for posting this story, and Damn Well Done to WG for supporting this Vet.
  6. o7, I did extensive research while writing my Greatest Generation novel, BB-39. One interesting, but not well known fact, is that the Arizona, BB-39 was supposed to be in the shipyard at Bremerton, Washington on December 7th. A collision earlier in the year required repairs in Pearl Harbor, and delayed her return to the West Coast.
  7. I have noticed that Newport has become harder, with what seems like, a lot more red ships toward the end. My teams can't seem to kill them fast enough, even if we are all still alive and healthy.
  8. I Played NF for the 5 years after beta, because I'm a naval history buff. The prime game designer quit shortly after beta. His spaghetti code resulted in several updates after ever new change. The wait between game starts was usually 10 minutes. The trading system was a major source of hate, spam, and theft. There was rampant cheating by Asian clans that drove many players away, including myself. Yes the games are different, and I wish WG could implement some of them. However, WOWS was a much better game during CBT than NF was after 5 years.
  9. I too have played every night between 2100 and 2300 PST, since CBT. I have played with the same computer (3 year old 4 quad gaming computer) and internet link, with only occasional game crashes. However, in the last 2 months the crashes have become regular (2 or 3 times per night). I have done all the usual fixes, (reinstalling and running the repair of the game) running internet speed tests (same as always), hardware and software tests, with no improvement. There does appear to be a correlation between Team Speak and times when the game is busy. It crashes if I activate the push to talk key. Over the last two weeks I have stopped playing in divisions, and the crashes have been reduced by about 50%. I'm going to live with it for a little while longer before taking the computer into the shop.
  10. My newest book goes live on November 16th at a discounted eBook price of $0.99. After The Days Of Infamy is an Alternate History Novel spanning the late 1920s into 1944. It will be the initial book in a three book series. I am a Naval History buff and the author/publisher of the Greatest Generation Novel BB-39, and several hard SF Books. This book departs from reality with the 1932 discovery of helium on the Japanese island of Hokido. A secret agreement between Japan and Germany results in a technology exchange that enables Japan to develop a fleet of huge airship aircraft carriers. The two attacks on December Seventh are made by over 300 planes from a fleet of four airship carriers. By the end of that week, a series of devastating strikes up and down the West Coast leave the aircraft, shipbuilding, and marine industries in ruins. This story does not include steam punk, fantasy, time travel, magic, elves or faeries. It does include some adult content, as well as fictional actions by the USS Fletcher and the USS Iowa. The deviations from historic technologies are based on what could have been accomplished with the availability of helium and a push in that direction. After The Days Of Infamy is now available for Pre-Order in Print and Kindle eBook forms from https://www.amazon.com/dp/B07JLVPGXD
  11. CaptnAndy

    Remembrance Day November 11th

    I'm wearing my poppy today, as a proud USN vet. Thanks to all who serve.
  12. CaptnAndy

    Thank You WG for the T5 Ranked Season

    As a solid 43% player since CBT (1944 model with vision, multitasking, and reaction time limitations) I have played each rank season until I became discouraged by the grind and the lack of success. I played this season all the way to the bitter end. I didn't rank out, but made it to level 2 with 2 stars, and it was fun. I did find the games during the last couple of weeks to be often very uneven (mostly wipeouts for one side).
  13. CaptnAndy

    Ships in movies (SPOILER ALERT!)

    One of my Favorite WW2 movies.
  14. CaptnAndy

    Having fun playing WoWs

    As a naval history buff, I love this game, in spite of being a mediocre player (43% WR) since CBT. My vision, reaction time, and multitasking abilities were degraded a couple of decades ago (I'm a 1944 model). I have played almost every night for a couple of hours since then, and do my best to be an asset to my team. I did play N**Y F***D for the 5 years after Beta, and this game was better in CBT then the other one was after 5 years. Damn Well Done WG. While I know how to play better than my WR shows, I still enjoy playing, in spite of my limited successes.