Another thread posed an interesting question, but that thread was not the appropriate place to discuss it and I apologize for cluttering the thread! Does bullet lift exist? Evidently Exbal and some of the the other ballistics programs seem to demonstrate that drop of some bullets is faster than similarly shaped other bullets. My admittedly decades old physics work didn't have a place for that, so I challenged the premise but several members pointed out that I was wrong. I've done some preliminary google searches and found three different sources who discount bullet lift: The Department of Energy being the most recognized and the first sited. Even Wikipedia has something to say on the subject, although I recognize Wikipedia may not be the most authoritative site. So here are the quotes, the first from the DOE's "Ask a Scientist" site. Question - Our students claim that when a bullet emerges from a horizontal rifle, it can take a rising path due to the spinning of the bullet. Is there a way for a bullet to rise? We think that Bernoulli effect is minimal to null in this situation.-----------------Nathan -A real bullet shaped projectile.... no. But a round projectile... maybe.In aerodynamics there is an effect known as the Magnus Effect. It would likely not apply to a bullet because of its shape. The bullet would likely continue to fly with the nose forward and the rifling would turn the bullet around its longitudinal (front to rear) axis. However, the Magnus Effect could effect a round projectile as fired from a musket or an old fashioned cannon ball. This could cause the ball to rise if were rotated properly around its lateral (left to right) axis while in flight. (Think of hitting a cue ball with back spin on a pool table. That is the kind of spin it would need.)I would expect that this effect would be most apparent with a slow-moving, light projectile of larger size. Perhaps it could be seen with slow motion photography if a Polystyrene foam ball were pitched with a great deal of back spin. I really do not know if it would be significant enough to measure, but it might be fun to try.Larry Krengel===================================================== No way.The fact that the bullet is spinning means that, on average, it'ssymmetrical about its line of flight, so why would any force exertedby air cause it to rise, rather than, say, go to the left? The onlything I can think of that would break the symmetry, and result in apreferred direction, would be *very* slightly higher air density belowthe bullet than above it, but this difference seems utterly negligible.I don't believe a bullet fired horizontally actually rises, or evenfalls more slowly than it would if simply dropped. However, I dobelieve a rifle's recoil could cause it to rotate about its center ofmass so that the barrel tips upward slightly while the bullet is stillwithin the barrel.Tim Mooney The second from a blogger who is interested in guns: In external ballistics a number of forces act on bullet flight, making for a royally nasty set of differential equations to solve. The basics, such as gravity and aerodynamic drag (including crosswinds), are conceptually pretty straightforward. One that I find interesting for some strange reason is the Magnus effect. The magnus effect is what makes curve balls curve. Topspin on a ball makes it fall faster than it otherwise would (provides "lift" downward), backspin makes it fall more slowly than it otherwise would (provides "lift" upward). Things get interesting when dealing with bullets. Since they spin around the axis of travel, the aerodynamic forces caused by the spin cancel each other out. However, add in a crosswind, and things get interesting. Take your standard bullet fired from a right-hand twist barrel. (Imagine a barrel, take your right thumb, point it along the direction of your imaginary barrel, and curl your fingers toward your palm. The bullet, which is traveling in the direction of your thumb, spins in the direction your fingers curl.) Looking from behind the bullet, the spin appears clockwise. (The right side is moving down, the left side is moving up.) Now, add in a cross wind coming from the right. The wind hitting the bullet from the right sees topspin. The right side of the bullet is spinning down, creating "lift" to push the bullet downwards. (like a curveball) This causes the bullet to fall faster than it otherwise would, causing the bullet to hit the target lower than it otherwise would. opposite effect. The spin creates lift, and the bullet falls more slowly than it otherwise would, causing the bullet to hit the target higher. The magnus effect on a normal bullet is small, small enough that it is almost always disregarded in small arms ballistic calculations, (Field artillery is another mater.) but, for some horribly geeky reason, I find it rather interesting. And finally, Wikipedia: The Magnus effect in external ballistics, also known as 'spin drift' Another context where the Magnus effect can be found is advanced external ballistics. A spinning bullet in flight is often subject to a sideways wind. In the simple case of horizontal wind, depending on the direction of rotation, the Magnus effect causes an upward or downward force to act on the projectile, affecting its point of impact. Even in a complete calm, with no sideways air movement at all, a real bullet will experience a small sideways wind component. This is because real bullets have a yaw motion that causes the nose of the bullet to point in a slightly different direction from the direction in which the bullet is actually traveling. This means that the bullet is "skidding" sideways at any given moment, and thus experiences a small sideways wind component.(yaw of repose) All in all, the effect of the Magnus force on a bullet is not significant when compared to other forces like drag. However, the Magnus effect has a significant role in bullet stability because the Magnus force does not act upon the bullet's center of gravity, but the center of pressure. This means that there is a Magnus force that affects the yaw of the bullet. The Magnus effect will act as a destabilizing force on any bullet with a center of pressure located ahead of the center of gravity, while conversely acting as a stabilizing force on any bullet with the center of pressure located behind the center of gravity. The location of the center of pressure depends on the flowfield structure, in other words, depending on whether the bullet is in super-sonic or sub-sonic flight. What this means in practice depends on the shape and other attributes of the bullet, in any case the Magnus force greatly affects stability because it tries to "twist" the bullet along its flight.