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I see a lot of bullet drop compensation computations but cant recall seeing a bullet rise computation. With gravity being less effective at really high altitudes above sea level (10k' or more), I would think that we should have a book to help shooters account for this. View Quote |
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Gravity diminishes by distance away from center of mass. So there is slightly less gravity at elevation above sea level. Enough to make a discernible difference? I highly doubt it. View Quote |
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Quoted: Astronauts where? An astronaut on earth experiences 100% of the gravity that we do on earth. An astronaut on the moon experiences about 17% of what we do. An astronaut in the International Space Station experiences about 90% of our gravity. If we ever land on Mars, it will be about 38% of earth's gravity. View Quote Could a treadmill or an exercise bike prevent this? |
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I have to come up 3 clicks at 100 yds due to the gravitational pull of my balls. Hope that helps.
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There are these organizations called "Air Forces" that have been building machines that are designed to work at sea level and at 30,000 feet. They have been doing it for 80 years now.
I know how P-51s and P-47s were designed to work when the air density decreased, and when engines had to be desigend with things like superchargers and such, but I forget how they were designed when gravity decreased. Perhaps there is a book on that. I believe when Hillary tried to scale Everest the Sherpa had to put some deep sea diver boots borrowed from Jacque Cousteau at the 25000 feet line, because a big problem at the top of Everest is the gravity is so low that the breeze blows people up into the sky. You can sorta hippity-hop the last thousand feet but the winds make it tricky. |
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I believe when Hillary tried to scale Everest the Sherpa had to put some deep sea diver boots borrowed from Jacque Cousteau at the 25000 feet line, because a big problem at the top of Everest is the gravity is so low that the breeze blows people up into the sky. You can sorta hippity-hop the last thousand feet but the winds make it tricky. View Quote If one were to take a nighttime stroll at the bottom of the Mariana Trench and fire a gun, while the surrounding water would lubricate the bullet, the higher gravity would cause it to drop to the seabed within a few feet of the muzzle. |
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While 10,000 feet makes no difference on ballistics as far as gravity is concerned it makes you wonder about the ballistics in zero g. If you shoot a bullet in space would it have a flat trajectory? "Determine the altitude after one orbit of a bullet fired at 3,000 feet per second from a gun mounted parallel to the long axis of a spacecraft whose altitude is 185 miles. Assume a circular orbit." |
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Gravity variations due to altitude are negligible. It's AIR DENSITY (and bullet drag due to that) which lessens at altitude.
One of the best technical discussions on this topic is a book by Robert Rinker entitled "Understanding Firearm Ballistics". The book is really intended to be a detailed technical discussion. It's got WAY too much detaail for your average hunter. But for a serious student of long range shooting, it's a REALLY useful read. |
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Sighted in my 300 win mag at 2500 feet at 200 yards. Zeroed in. Got to Utah at 7500 feet and I was shooting 6” too high at the same distance. View Quote |
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So what you're saying is that an astronaut dropped onto the surface of Jupiter would quickly become a puddle of goo? Flatter than a pancake with just his little eyes bugging out. Could a treadmill or an exercise bike prevent this? View Quote View All Quotes View All Quotes Quoted:
Quoted: Astronauts where? An astronaut on earth experiences 100% of the gravity that we do on earth. An astronaut on the moon experiences about 17% of what we do. An astronaut in the International Space Station experiences about 90% of our gravity. If we ever land on Mars, it will be about 38% of earth's gravity. Could a treadmill or an exercise bike prevent this? |
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Im giving you a double What happens in real life does not always correlate to what the guy in the wheelchair tells us it is View Quote View All Quotes View All Quotes |
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LOL. No it is not. Is the gravity on the moon the same as Earth? To the OP, the bullet does not rise above the bore axis, it just doesn't drop as fast as at sea level. View Quote View All Quotes View All Quotes |
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no, it has less acceleration back toward the gun. It speeds up until it leaves the barrel, may get a bit of a gas jet kick and then immediately starts slowing down. For an object to go faster in any direction it must have a force acting on it.
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Isn’t that a myth? Or is it the female orgasm? View Quote View All Quotes View All Quotes |
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Trick question; Jupiter doesn't have a solid surface to land on! But the gravity near Jupiter would be about 240% of earth. If it were solid, a strong person could stand up, but they would be exhausted in short order. View Quote View All Quotes View All Quotes Quoted:
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Quoted: Astronauts where? An astronaut on earth experiences 100% of the gravity that we do on earth. An astronaut on the moon experiences about 17% of what we do. An astronaut in the International Space Station experiences about 90% of our gravity. If we ever land on Mars, it will be about 38% of earth's gravity. Could a treadmill or an exercise bike prevent this? That being the case, would said astronaut simply drop to the center of the planet, suspended there in a state of gravitational equilibrium? Since all of the planet's mass is surrounding him equally in all directions, would the gravity, instead of crushing him, pull him apart in all directions? A leg here. An arm there. Spleen maybe get launched towards Earth and end up in Cleveland? |
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Yes it does. Shoot at altitude in Colorado after zeroing at sea level, it makes a big difference at 500 yards. View Quote View All Quotes View All Quotes |
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I don't know how many otherwise intelligent people have argued to me that bullets rise. Even had one or two take it a step further and argue that they create lift like a wing.
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I'm a geologist, so I actually know something about this. There is a tiny bit less gravitational attraction at altitude. More importantly, there is some difference in the gravitational constant from place to place, independent of altitude, having to do with the density of the country rock and what is happening with tectonic plate/plates beneath your location. In other words, there is very, very little (read: almost nil) difference between shooting at altitude due to gravitational effects over shooting at sea level. I suspect the reduced air pressure is far more influential than the reduced gravity. View Quote View All Quotes View All Quotes Quoted:
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There is a tiny bit less gravitational attraction at altitude. More importantly, there is some difference in the gravitational constant from place to place, independent of altitude, having to do with the density of the country rock and what is happening with tectonic plate/plates beneath your location. In other words, there is very, very little (read: almost nil) difference between shooting at altitude due to gravitational effects over shooting at sea level. I suspect the reduced air pressure is far more influential than the reduced gravity. |
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Astronauts where? An astronaut on earth experiences 100% of the gravity that we do on earth. An astronaut on the moon experiences about 17% of what we do. An astronaut in the International Space Station experiences about 90% of our gravity. If we ever land on Mars, it will be about 38% of earth's gravity. View Quote View All Quotes View All Quotes Quoted:
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While 10,000 feet makes no difference on ballistics as far as gravity is concerned it makes you wonder about the ballistics in zero g. If you shoot a bullet in space would it have a flat trajectory? |
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I don't know how many otherwise intelligent people have argued to me that bullets rise. Even had one or two take it a step further and argue that they create lift like a wing. View Quote However, the negligible lift it does provide isn't even close to offsetting or even slowing any amount of drop. Especially since it isn't powered, it's essentially a "glide" fuselage with shit l/d. That's why only BC calculations, for all practically, matter. When talking to the average person though; " bullets don't have lift." ETA - to OP. BC accounts for higher elevations with air density as part of the equation, it doesn't care about gravity (it's a constant). Gravity doesn't have near the impact, in elevations where you can be alive to use a gun, to matter enough to change. |
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Most are stymied by the intricacies of shooting above 10,000ft. This shot was particularly technical. Step 1 Look for Muley buck. https://www.AR15.Com/media/mediaFiles/309674/IMG_0026_jpg-747617.JPG Step 2 Find Muley buck https://www.AR15.Com/media/mediaFiles/309674/P1000110_jpg-747618.JPG Step 3 Setup shot and wait for muely buck to stand up @680 yds. https://www.AR15.Com/media/mediaFiles/309674/IMG_0032_jpg-747619.JPG Step 4 Hold low and Profit. https://www.AR15.Com/media/mediaFiles/309674/IMG_0039_jpg-747627.JPG View Quote That Buck and landscape are truly amazing. I am genuinely jealous that you get to hunt a place like that. |
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At an altitude of 100,000 feet, gravity is smaller by only about 1%. Twenty miles is only a tiny fraction of the size of the earth, and doesn't even reach the upper atmosphere.
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Gravitons kids
The latest theory is that gravity pushes instead of pulls |
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I always thought that was what the shoulder thing that goes up was for. It automatically corrects for gravitational bullet rise.
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Quoted: @JohnBurns That Buck and landscape are truly amazing. I am genuinely jealous that you get to hunt a place like that. View Quote A few more pictures of low gravity. Attached File Attached File |
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great thread so far.
I'm pretty sure bullets only rise once you shoot them off the edges. Something to do with the air flow going upwards from the ocean flow as it goes over the edge. |
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So many here have said, quite vehemently at times, that bullets do not rise because they do not generate lift, and therefore their acceleration toward the ground is essentially unhindered.
This may be true for smoothbore weapons. However most rifles are, well, rifled. A 55gr FMJBT m193 has a rated muzzle velocity of 3,250 fps. Which means that out of a 1/7 twist barrel that bullet is spinning at ~330,000 rpm. In that first tiny fraction of a millisecond after the bullet leaves the bore, it will achieve gyroscopic stability. This is why a rifle is more accurate than a smoothbore. And in that one infinitesimal brief and shining moment the bullet may indeed rise slightly above the bore. |
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Only thing that changes at altitude is air density and temperature. All trajectory calcs use environment variables to change air resistance.
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How do you account for bullet rise at higher elevations? View Quote |
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Next OP wants to know why a bullet dropped and a bullet fired horizontally at the same height will strike the ground at the same time.
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Next OP wants to know why a bullet dropped and a bullet fired horizontally at the same height will strike the ground at the same time. View Quote View All Quotes View All Quotes Quoted:
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Gravity is always working so bullets are always falling. They don’t rise. People don’t understand gravity. That Newton guy was full of shit. |
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Gravity diminishes by distance away from center of mass. So there is slightly less gravity at elevation above sea level. Enough to make a discernible difference? I highly doubt it. View Quote Air density is the only factor that really matters here. |
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