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#81
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casette shifting, again
On Sun, 16 Dec 2018 21:15:00 -0500, Frank Krygowski
wrote: On 12/16/2018 7:28 PM, John B. Slocomb wrote: You are ignoring the effect of air resistance which means that the speed of the projectile decreases with time during it's flight. And, as the decrease in velocity results in an effective decrease in air resistance the velocity decrease is not linier from muzzle to target. For example, taken from a radar generated ballistics table a test projectile fired at an initial velocity of 2,723 ft/s drops to 2,332 at 300 m, 1981 at 600, 1663 at 900, and 1384 at 1200. The decrease in velocity and therefore the decrease in drag is 391 ft/s at 300 M, 351 from 300 to 600, 318 from 600 - 900 and 279 from 900 - 1200. Yep. It's far from simple. If it were, lots more people would be good shots. :-) Being a good shot has very little or nothing to do with ballistics :-) More with having a good sight picture, steady hold and good trigger squeeze :-) cheers, John B. |
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#82
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OT Cobol
On Sun, 16 Dec 2018 21:34:57 -0500, Frank Krygowski
wrote: On 12/16/2018 7:38 PM, news18 wrote: On Sun, 16 Dec 2018 10:54:49 -0600, AMuzi wrote: Why in the world would anyone want to use Emacs, (by the way the proper name is "GNU Emacs") an application that is 40 years old. Yes, I know that it can do many strange and wondrous things but when you get right down to it, it is hardly the weapon of choice for writing a book, posting to USENET or keeping one's shopping list current. Well, John, customers of our s who are 'retired' get amazingly lucrative offers to rework/rewrite COBOL systems. Some of the 'obsolete' languages are critically undersupported and in the case of major bank mainframes, irreplaceable. When I was younger, I had a semester of Cobol in a degree course, but never sought work as a cobol programmer. Worse, after having to hack a few cobol programs to produce extra reports for a company where I was doing other stuff, I unwisely listed it on my resume as a side skill. Offers of work flooded in and I quickly emoved any mention. My major objection was that it was largly the financial sector and I just didn't want to work in that field. Yes, companies will pay big money for "obsolete" skills and hardware when the cost of replacing the program/hardware/system is expensive. I once sold about 15 ancient Network Interface Cards for about ten times the price of newer, faster better NICs because their integrated manufacturing factory relied on these ancient cards for interfacing. We had an ancient CNC milling machine in one school laboratory. The machine was in great shape mechanically (school machines accumulate very few hours compared to industrial ones) but the controller gave more and more trouble as the years went on. The faculty member who worked with it had a harder and harder time getting support. Finally, one time he called with yet another problem, he was told "The only guy here who knew that controller has died." A civil engineer that worked for us on one project told me about working on a job where they wanted to build a wooden bridge. Apparently the bridge had to support some serious weight and he got stuck with designing it. Not having ever even thought about wooden bridges he had no idea where to start. He finally thought that "Hey! The railroads used to built wooden bridges" and called the railroad and lo and behold there was still some of the old design data in the files. cheers, John B. |
#83
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casette shifting, again
On 12/16/2018 9:57 PM, John B. Slocomb wrote:
On Sun, 16 Dec 2018 21:15:00 -0500, Frank Krygowski wrote: On 12/16/2018 7:28 PM, John B. Slocomb wrote: You are ignoring the effect of air resistance which means that the speed of the projectile decreases with time during it's flight. And, as the decrease in velocity results in an effective decrease in air resistance the velocity decrease is not linier from muzzle to target. For example, taken from a radar generated ballistics table a test projectile fired at an initial velocity of 2,723 ft/s drops to 2,332 at 300 m, 1981 at 600, 1663 at 900, and 1384 at 1200. The decrease in velocity and therefore the decrease in drag is 391 ft/s at 300 M, 351 from 300 to 600, 318 from 600 - 900 and 279 from 900 - 1200. Yep. It's far from simple. If it were, lots more people would be good shots. :-) Being a good shot has very little or nothing to do with ballistics :-) More with having a good sight picture, steady hold and good trigger squeeze :-) Depends how far away you are, no? -- - Frank Krygowski |
#84
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casette shifting, again
On 17/12/18 1:57 pm, John B. Slocomb wrote:
On Sun, 16 Dec 2018 21:15:00 -0500, Frank Krygowski wrote: On 12/16/2018 7:28 PM, John B. Slocomb wrote: You are ignoring the effect of air resistance which means that the speed of the projectile decreases with time during it's flight. And, as the decrease in velocity results in an effective decrease in air resistance the velocity decrease is not linier from muzzle to target. For example, taken from a radar generated ballistics table a test projectile fired at an initial velocity of 2,723 ft/s drops to 2,332 at 300 m, 1981 at 600, 1663 at 900, and 1384 at 1200. The decrease in velocity and therefore the decrease in drag is 391 ft/s at 300 M, 351 from 300 to 600, 318 from 600 - 900 and 279 from 900 - 1200. Yep. It's far from simple. If it were, lots more people would be good shots. :-) Being a good shot has very little or nothing to do with ballistics :-) More with having a good sight picture, steady hold and good trigger squeeze :-) In addition, I've always found that estimating the distance to a target is rather critical. Oh, and the wind and how far from aiming generally horizontal. -- JS |
#85
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casette shifting, again
On Sun, 16 Dec 2018 22:59:23 -0500, Frank Krygowski
wrote: On 12/16/2018 9:57 PM, John B. Slocomb wrote: On Sun, 16 Dec 2018 21:15:00 -0500, Frank Krygowski wrote: On 12/16/2018 7:28 PM, John B. Slocomb wrote: You are ignoring the effect of air resistance which means that the speed of the projectile decreases with time during it's flight. And, as the decrease in velocity results in an effective decrease in air resistance the velocity decrease is not linier from muzzle to target. For example, taken from a radar generated ballistics table a test projectile fired at an initial velocity of 2,723 ft/s drops to 2,332 at 300 m, 1981 at 600, 1663 at 900, and 1384 at 1200. The decrease in velocity and therefore the decrease in drag is 391 ft/s at 300 M, 351 from 300 to 600, 318 from 600 - 900 and 279 from 900 - 1200. Yep. It's far from simple. If it were, lots more people would be good shots. :-) Being a good shot has very little or nothing to do with ballistics :-) More with having a good sight picture, steady hold and good trigger squeeze :-) Depends how far away you are, no? Yes, to a certain extent. In the 1,000 yard rifle shooting where a heavy bullet fired at a high velocity is required ballistics enter into the equation only to the extent that the average shooter knows what calibers work best. Or more frankly what doesn't work - the 7.62x51 NATO (.308 Winchester) doesn't work and one of the .300 or larger magnums works better. But with all the ballistics in the world, still, the major requirements are still a firm stance, good sight picture and a good trigger squeeze. Ballistics would enter into it in the in the sense of selection of the correct ammunition for the course of fire. That the ammunition is constant in muzzle velocity, and accurate in the weapon used - even in ..22 ammunition some makes/lots shoot better than others. The big military teams, for example, buy large quantities of ammunition and then test each lot in an enclosed test range. I once did a little "big bore", i.e., .30 caliber, military match shooting, 100,200 and 300 yard, and nobody even talked about ballistics. Other then the basic sight setting was "this" and 200 yds was 7 clicks up, etc. cheers, John B. |
#86
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casette shifting, again
On Mon, 17 Dec 2018 15:16:36 +1100, James
wrote: On 17/12/18 1:57 pm, John B. Slocomb wrote: On Sun, 16 Dec 2018 21:15:00 -0500, Frank Krygowski wrote: On 12/16/2018 7:28 PM, John B. Slocomb wrote: You are ignoring the effect of air resistance which means that the speed of the projectile decreases with time during it's flight. And, as the decrease in velocity results in an effective decrease in air resistance the velocity decrease is not linier from muzzle to target. For example, taken from a radar generated ballistics table a test projectile fired at an initial velocity of 2,723 ft/s drops to 2,332 at 300 m, 1981 at 600, 1663 at 900, and 1384 at 1200. The decrease in velocity and therefore the decrease in drag is 391 ft/s at 300 M, 351 from 300 to 600, 318 from 600 - 900 and 279 from 900 - 1200. Yep. It's far from simple. If it were, lots more people would be good shots. :-) Being a good shot has very little or nothing to do with ballistics :-) More with having a good sight picture, steady hold and good trigger squeeze :-) In addition, I've always found that estimating the distance to a target is rather critical. Oh, and the wind and how far from aiming generally horizontal. I don't know about the present rifles but back in the day when most 1,000 match shooters used either a Springfield or Garand 30-06 on a windy day the aiming point might be 2 targets to the right and 3 clicks to the left :-) And even in golf the distance to the target is important :-) In fact golf and baseball are probably the only two sports where the players actually think and use ballistics. Possibly also cricket although I'm not familiar with that sport. Golfers can, by how they hit the ball, make it curve right or left or straight and even control the distance the ball rolls after it hits the ground, to some extent. Baseball pitchers can make the ball do all kinds of wondrous things by how they hold and release the ball. cheers, John B. |
#87
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OT Cobol
On 12/16/2018 4:38 PM, news18 wrote:
snip Yes, companies will pay big money for "obsolete" skills and hardware when the cost of replacing the program/hardware/system is expensive. I once sold about 15 ancient Network Interface Cards for about ten times the price of newer, faster better NICs because their integrated manufacturing factory relied on these ancient cards for interfacing. A couple of months ago I had dinner with a college roommate that I had not seen for about 30 years. He is a physicist and works at an aerospace company in Southern California. He is still programming in Fortran. Speaking of NICs, I worked for the first networking company for personal computers, before Novell, Corvus, or 3COM. The first cards we built, before I worked there, were for the Apple II, the Commodore PET, and the TRS-80. One customer, a school district, came back, long after the Apple II NICs were discontinued and wanted more Apple II NICs. We told them that it was an obsolete product and that we had no more. They asked us "how much to make some" and we quoted them a very high price because we had no desire to produce more, and they said "okay." We still had the hand-taped PC board film, and all the components were still available, so we could build them pretty quickly. |
#88
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casette shifting, again
On 12/17/2018 1:20 AM, John B. Slocomb wrote:
On Sun, 16 Dec 2018 22:59:23 -0500, Frank Krygowski wrote: On 12/16/2018 9:57 PM, John B. Slocomb wrote: On Sun, 16 Dec 2018 21:15:00 -0500, Frank Krygowski wrote: On 12/16/2018 7:28 PM, John B. Slocomb wrote: You are ignoring the effect of air resistance which means that the speed of the projectile decreases with time during it's flight. And, as the decrease in velocity results in an effective decrease in air resistance the velocity decrease is not linier from muzzle to target. For example, taken from a radar generated ballistics table a test projectile fired at an initial velocity of 2,723 ft/s drops to 2,332 at 300 m, 1981 at 600, 1663 at 900, and 1384 at 1200. The decrease in velocity and therefore the decrease in drag is 391 ft/s at 300 M, 351 from 300 to 600, 318 from 600 - 900 and 279 from 900 - 1200. Yep. It's far from simple. If it were, lots more people would be good shots. :-) Being a good shot has very little or nothing to do with ballistics :-) More with having a good sight picture, steady hold and good trigger squeeze :-) Depends how far away you are, no? Yes, to a certain extent. In the 1,000 yard rifle shooting where a heavy bullet fired at a high velocity is required ballistics enter into the equation only to the extent that the average shooter knows what calibers work best. Or more frankly what doesn't work - the 7.62x51 NATO (.308 Winchester) doesn't work and one of the .300 or larger magnums works better. But with all the ballistics in the world, still, the major requirements are still a firm stance, good sight picture and a good trigger squeeze. Ballistics would enter into it in the in the sense of selection of the correct ammunition for the course of fire. That the ammunition is constant in muzzle velocity, and accurate in the weapon used - even in .22 ammunition some makes/lots shoot better than others. The big military teams, for example, buy large quantities of ammunition and then test each lot in an enclosed test range. I once did a little "big bore", i.e., .30 caliber, military match shooting, 100,200 and 300 yard, and nobody even talked about ballistics. Other then the basic sight setting was "this" and 200 yds was 7 clicks up, etc. Here's some of what I had in mind: https://www.longrangehunting.com/thr...results.80403/ https://www.huntinggearguy.com/tips/...range-hunting/ I suppose I shouldn't have said "lots more people." It really applies to people shooting at relatively long but variable ranges. -- - Frank Krygowski |
#89
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casette shifting, again
On Mon, 17 Dec 2018 07:28:37 +0700, John B. Slocomb
wrote: Acceleration of gravity = g = 32 ft/sec/sec Let's say the trajectory height is 100 ft and the range is 1000 ft. sqrt(height/0.5(g)) = time_of_flight sqrt(100/0.5(32)) = (10/4) = 2.5 sec At 1000ft, the muzzle velocity would be 1000/2.5 = 400ft/sec Or something like that. You are ignoring the effect of air resistance which means that the speed of the projectile decreases with time during it's flight. And, as the decrease in velocity results in an effective decrease in air resistance the velocity decrease is not linier from muzzle to target. For example, taken from a radar generated ballistics table a test projectile fired at an initial velocity of 2,723 ft/s drops to 2,332 at 300 m, 1981 at 600, 1663 at 900, and 1384 at 1200. The decrease in velocity and therefore the decrease in drag is 391 ft/s at 300 M, 351 from 300 to 600, 318 from 600 - 900 and 279 from 900 - 1200. :-) Ok, I yield. Air resistance is significant and can't be ignored. "Projectile Motion with Air Resistance" http://farside.ph.utexas.edu/teaching/336k/Newtonhtml/node29.html We thus conclude that if air resistance is significant then it causes the horizontal range of the projectile to scale linearly, rather than quadratically, with the launch velocity. Methinks I could use this to produce a tolerable balistic approximation, which could be used to calculate the muzzle velocity given the impact velocity at a known distance. However, my math sucks, I'm still doing battle with two kidney stones, and need to do some repairs after last nights rain. Thanks for the corrections. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#90
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casette shifting, again
On Sat, 15 Dec 2018 15:59:21 -0600, AMuzi wrote:
snip I left school without having slept through even one physics class. My reference work here is a 1955 high school textbook for $1 (9 Kr). I don't know all of even that, but I understand the world well enough to know that this headline last week: https://www.dailymail.co.uk/sciencet...US-Army-begin- using-new-automatic-rifles-fire-power-TANK-soon-2022.html was completely ridiculous. The chamber pressures are in the same range, but not power, not even within a magnitude*! Power is work over time. Without some grasp of the actual world, you would not have laughed aloud when reading the headline, etc. *A typical 120mm tank round is 7.5 kilos of depleted uranium moving at 1700 m/s. The new 6.8 rifle typically moves 7.5 grams at 850 m/s. That's why you need basic physics. There's a reason the Brits call it the "Daily Fail", you know. -- davethedave |
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