Shell holder dimensions

Another "point of relativity": winds can push bullets sideways off their trajectory. Winds can't do that unless the wind velocity exceeds that of the bullet's. It is the airmass that the bullet is entrained in that is moving and changing the bullet's flightpath.:D
 
Well, not really. If the bullet were entrained in the air mass, then spindrift couldn't happen in still air, but it does.

If you drive through a snow shower at a constant highway speed at night (headlights on) you will see the snow rushing at your windshield like a starfield on a Star Trek bridge viewscreen. If the wind starts blowing at a constant speed across the road, instead of the snow hitting your car on the side, you see it come toward your windshield from an angle. That angle is the direction of the intercept path snowflakes are coming along to your car. It is equal to the arctangent of the car speed divided into the crosswind speed. If your car is going 60 mph and the crosswind is 10 mph, the arctangent of 10/60 is 9.46°, so the snow will appear to be coming from 9.46° off of straight ahead. Moreover, the speed with which the snow comes at your car is the square root of the sum of the squares of the two velocities, or 60.83 mph, some of the speed coming from your car and some from the crosswind. The combined winds as a net angle and speed is called a wind vector.

Well, the same thing happens with air molecules and your bullet as did with the snowflakes and car. If your bullet is traveling 2000 mph (2933 fps) and the crosswind is 10 mph, the combined speed and angle are 2000.025 mph and 0.2865°. So the bullet sees a headwind of that slightly greater speed coming at it from that small angle off straight ahead. The force of that off-angle wind causes the bullet to precess around its center of gravity until it settles flying into the angled wind. So the bullet is now going downrange cocked at that small angle (gnoring the the yaw of repose), and with the angled air stream blowing over it from nose to tail. This means drag on the bullet is no longer straight back toward the rifle that fired it, but rather it is pulling back on the bullet at that small angle. This means drag not only slows the bullet down, but pulls it slightly to the side.

In the case of a crosswind that is faster than the bullet, the vector angle simply exceeds 45°.

In 1852 a French artillery officer named Isadore Didion published a coursebook on basic ballistics with a simple formula for calculating wind deflection. You calculate the time of flight the projectile would have in a vacuum, which is the range divided by the muzzle velocity. This is because a vacuum creates no drag and doesn't slow the projectile down. Then you subtract that number from the actual time of flight (found by multiple ballistic pendulum firings at multiple ranges back then). The difference in time represents the overall effect of drag as a function of time. If you multiply that time by the crosswind speed, you get the inches of deflection because the crosswind component of the wind vector has an effect proportional to overall drag since the vector combines the two winds.
 
Ooooh! Pulled a vacuum on it? Made some of it it give up heat of vaporization so the rest froze? That's cool!
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That is exactly what he did, using a vacuum jar. Reducing the air pressure on the surface reduced the temp needed to boil, and boiling removes heat from the water, until it freezes.

There was a "steam bubble" trapped under the ice when it formed, way cool
 
Well, not really. If the bullet were entrained in the air mass, then spindrift couldn't happen in still air, but it does.

If you drive through a snow shower at a constant highway speed at night (headlights on) you will see the snow rushing at your windshield like a starfield on a Star Trek bridge viewscreen. If the wind starts blowing at a constant speed across the road, instead of the snow hitting your car on the side, you see it come toward your windshield from an angle. That angle is the direction of the intercept path snowflakes are coming along to your car. It is equal to the arctangent of the car speed divided into the crosswind speed. If your car is going 60 mph and the crosswind is 10 mph, the arctangent of 10/60 is 9.46°, so the snow will appear to be coming from 9.46° off of straight ahead. Moreover, the speed with which the snow comes at your car is the square root of the sum of the squares of the two velocities, or 60.83 mph, some of the speed coming from your car and some from the crosswind. The combined winds as a net angle and speed is called a wind vector.

Well, the same thing happens with air molecules and your bullet as did with the snowflakes and car. If your bullet is traveling 2000 mph (2933 fps) and the crosswind is 10 mph, the combined speed and angle are 2000.025 mph and 0.2865°. So the bullet sees a headwind of that slightly greater speed coming at it from that small angle off straight ahead. The force of that off-angle wind causes the bullet to precess around its center of gravity until it settles flying into the angled wind. So the bullet is now going downrange cocked at that small angle (gnoring the the yaw of repose), and with the angled air stream blowing over it from nose to tail. This means drag on the bullet is no longer straight back toward the rifle that fired it, but rather it is pulling back on the bullet at that small angle. This means drag not only slows the bullet down, but pulls it slightly to the side.

In the case of a crosswind that is faster than the bullet, the vector angle simply exceeds 45°.

In 1852 a French artillery officer named Isadore Didion published a coursebook on basic ballistics with a simple formula for calculating wind deflection. You calculate the time of flight the projectile would have in a vacuum, which is the range divided by the muzzle velocity. This is because a vacuum creates no drag and doesn't slow the projectile down. Then you subtract that number from the actual time of flight (found by multiple ballistic pendulum firings at multiple ranges back then). The difference in time represents the overall effect of drag as a function of time. If you multiply that time by the crosswind speed, you get the inches of deflection because the crosswind component of the wind vector has an effect proportional to overall drag since the vector combines the two winds.
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I never took physics, so you have me at a disadvantage. ;)

The video you linked is actually key--because it shows the effect of "frame of reference" as to how to interpret what is happening on the movement of objects.This is true for both the snow in your example as well as the flight of the bullet--once they leave the ground the frame of reference is the airmass they are in--not points on the ground. They are, essentially, aircraft, which is where my experience and opinion comes from on the forces affecting a projectile's flight path vis windage change. The force of gravity is a constant and drag may affect the time spent in a given body of air--and the spinning bullet itself may have gyroscopic properties that effectively act as "control surfaces"--but the force of wind itself does not pitch, yaw or roll a bullet (unless you are shooting in one heck of a storm).
 
AB,

That's TurboCAD. Much less expensive and can export compatible files. I've used it since V.1.0 circa 1990. It doesn't do everything SolidWorks does; just most of them.


Stagpanther said:
The video you linked is actually key--because it shows the effect of "frame of reference" as to how to interpret what is happening on the movement of objects.This is true for both the snow in your example as well as the flight of the bullet--once they leave the ground the frame of reference is the airmass they are in--not points on the ground. They are, essentially, aircraft, which is where my experience and opinion comes from on the forces affecting a projectile's flight path vis windage change. The force of gravity is a constant and drag may affect the time spent in a given body of air--and the spinning bullet itself may have gyroscopic properties that effectively act as "control surfaces"--but the force of wind itself does not pitch, yaw or roll a bullet (unless you are shooting in one heck of a storm).
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That's pretty close to right. The wind vector does affect the pitch and yaw of the bullet, but it is a small amount called the yaw of repose. A high-power rifle bullet typically settles into this attitude pitched up about a tenth of a moa and with a sideslip yaw of around five to ten times that depending on the rate of spin. The small upward pitch catches just enough air under the bullet nose so precession resulting from its drag force maintains the sideslip yaw. The sideslip yaw catches just enough air on the side of the bullet so precession resulting from that drag force causes the bullet to keep turning its tip down to match the bend of the trajectory. This is how a bullet maintains nose-first flight in the air (in a vacuum it would simply maintain its initial attitude in flight). The slight upward pitch also adds lift to the bullet, but it is so small it typically causes only about 1/2" higher point of impact at 1000 yards. Drag from the fifteen to twenty times larger sideslip yaw steers the bullet to the side (right side for right-hand spinning bullets and vice-versa for left-hand spin) and is what causes spindrift, which is typically enough to require a windage correction of around one moa as compared to shooting at 100 yards.

You are spot on about the frame of reference. The shooter's usual frame of reference is the firing line, which makes it very difficult to visualize the interaction of the bullet and the air. But when the bullet becomes the frame of reference, there is a very simple demonstration you can give shooters to explain wind deflection. Put a piece of paper in front of them and tell them it represents the air mass the bullet must fly through on its way to the target. The firing line is one edge and the target is on the other. Have them hold the tip of a pencil on the paper near the edge near the "firing line". Then slide the target side of the paper toward the pencil so it draws a line straight from the firing line side to the target side, asking them to pay attention to the direction they feel the drag on the pencil point in. It will be straight back along the line, of course. Then repeat, this time adding a little sideways motion to the slide from firing line to target to represent the crosswind motion of the air. Now they get a diagonal line across the page, and they feel diagonal drag back along the direction the new line was drawn in. You then explain the sideways part of the drag on the diagonal is what moves the bullet to the side in a crosswind.
 
Lmao . Can’t you just hang the piece a paper between your thumb and finger then blow air towards the paper . When the paper starts to move you say that’s what makes your bullet move lol . The only yaw-ning I’m experiencing is me reading those explanations ;-)
 
Nope. The hanging paper is experiencing the wind blowing directly on its side. That never happens to a bullet. It gets out of the way before sideways-moving air can impinge on it, so it only experiences glancing impact with the air molecules coming into it at that vector angle.

I wish it were simpler and less sleep-inducing for you and the many others who undoubtedly feel the same way. Alas, getting the complexity to change would require convincing God he made an assembly error in putting the laws of the universe together.
 
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