"An iPhone app called Bullet Flight enables snipers to calculate range and trajectory for their shots, and built-in satellite-positioning allows local weather conditions to be taken into account. The basic version costs $3.99 and the full military one--which even calculates how the Coriolis effect from the rotation of the Earth will influence a bullet’s flight--costs $29.99."
Am I the only one who find this strange? Even with local weather information, there's a lot of uncertainty on wind speed and direction, humidity, etc etc. Does the Coriolis effect actually matter or is it negligible?
Agreed. The shooter would still definitely have to make local estimations of wind speed and direction, there's no way the app could get that data in real-time or in sufficient resolution.
My understanding is that the Coriolis Effect only comes into play at very long ranges. That being said snipers nowadays are more and more using heavy caliber (generally .50BMG) rounds and taking their shots at much longer distances than in previous times.
As an example: http://en.wikipedia.org/wiki/Rob_Furlong
Rob Furlong made a shot against a target that was 2,430 meters away. At that range the bullet's flight time was just under 3 seconds! At that sort of range pretty much anything can affect the bullet enough to deflect it off target...
Define "pretty well". I am no sniper, but I suspect these guys are used to hitting targets at distances of 1,000 meters. Wind speed, air temperature and humidity vary over time and space. A good sniper can probably estimate these with some accuracy, but there's still a lot of uncertainty left on what the bullet will hit. If the Coriolis effect contributes with very little uncertainty by comparison, then accounting for it is not going to help much.
Let's face it: without the numbers, we're talking plain nonsense.
The numbers are tractable, though. The circumference of the earth is very close to 40Mm (useful fact to know -- it was one of the original design points for the meter). At the equator (where the rotational acceleration is highest, even though coriolis itself is zero) we have a velocity of 40e6 / (24 x 60 x 60) == 463m/s. So the acceleration (v^2/r) of the ground the target is standing on relative to the free-flying bullet is 0.034 m/s^2. Taking the 3-second shot example from above, the target will move 0.5 x 0.034 x 3^2 == 15.3cm during the bullet's flight.
And yeah, a six-inch error is just about what I'd consider the maximum tolerance if you're trying to hit someone's torso. So it seems that yes, the numbers back it up.
I'm curious too, so I googled around a bit an I thought this was the best answer:
"As an ex British markman/sharpeshooter, we are trained to take everything into account, the coriolis effect is taught but very rarely acted upon, your generally close enough to see someones face when taking a shot. The Barret M95 has an incredible range, and when your talking anything over 1 click, wind, humidity, spin are all more important than the coriolis effect, but when it comes to taking a shot you do not want to miss, a miss can get you killed, you keep your mind on all variables."
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[ 2.8 ms ] story [ 32.5 ms ] threadIn what sense? Would you care to elaborate on that?
Radar? First a weapon, then civilian.
Nuclear power? First a weapon, then adapted for peaceful purposes.
The list goes on: radio, flying, submarines, even the internet was developed with military funding.
Am I the only one who find this strange? Even with local weather information, there's a lot of uncertainty on wind speed and direction, humidity, etc etc. Does the Coriolis effect actually matter or is it negligible?
My understanding is that the Coriolis Effect only comes into play at very long ranges. That being said snipers nowadays are more and more using heavy caliber (generally .50BMG) rounds and taking their shots at much longer distances than in previous times.
As an example: http://en.wikipedia.org/wiki/Rob_Furlong Rob Furlong made a shot against a target that was 2,430 meters away. At that range the bullet's flight time was just under 3 seconds! At that sort of range pretty much anything can affect the bullet enough to deflect it off target...
Yes, there's some uncertainty, but I'd assume snipers are used to estimating or measuring these values pretty well.
Let's face it: without the numbers, we're talking plain nonsense.
And yeah, a six-inch error is just about what I'd consider the maximum tolerance if you're trying to hit someone's torso. So it seems that yes, the numbers back it up.
Yay, physics is fun!
"As an ex British markman/sharpeshooter, we are trained to take everything into account, the coriolis effect is taught but very rarely acted upon, your generally close enough to see someones face when taking a shot. The Barret M95 has an incredible range, and when your talking anything over 1 click, wind, humidity, spin are all more important than the coriolis effect, but when it comes to taking a shot you do not want to miss, a miss can get you killed, you keep your mind on all variables."
[Found here: http://www.answerbag.com/q_view/569190]
Would have love to have more details of other consumer grade products they buy.