Shooting up

[Elnathan]

If the angle of the shot is plus or minus 45 degrees, aim low on the target or game.

I aim at my target, the angle should make no difference - gravity is a constant regardless of your initial angle and will attract the ball in the same way. The ballistic trajectory really doesn't change whether you are shooting dead level, down or up. The only thing that changes is where the arc is interrupted by the ground.

This is incorrect, at least technically. Gravity remains a constant, but the angle at which it exerts its force differs depending on the elevation of the shot, and that will alter the trajectory.

Consider: If the barrel is exactly horizontal, gravity exerts a force at exactly 90 degrees to the force of the gunpowder, so the bullet will travel forwards until gravity pulls it into the ground, being slowed by wind resistance at the same time. This is the basic trajectory that we are all familiar with. If you shoot the gun straight up/directly way from the center of the earth, gravity works directly against the force of the propellant - the bullet will travel directly up until the combined effects of wind resistance and gravity bring it to a halt, at which point gravity will pull it back to earth and wind resistance will continue to slow it down. If you shoot the gun directly towards the earth, gravity and the force of the propellant will work together, so that the bullet will travel in a straight path, slowed only by wind resistance, until it strikes the earth.

So, as far as I can determine, shooting at an angle either upward or downward will cause the trajectory to flatten, at least at the initial stages in which we are interested. Dunno if the longer flight time of an upward angle, giving wind resistance more time to work, will result in a more curved trajectory overall than a horizontal shot, but it will definitely be different.

A lot of this is pretty theoretical and probably doesn't show up much when in the field, but if you are shooting a squirrel way up in a tree over your head, the ball isn't going to strike relative the sights in the same way it does when firing horizontally. I haven't done any of this kind of shooting myself, but I've been told that the best way to handle the problem is, instead of calculating the distance in a direct line between yourself and the squirrel, look at the distance between yourself and the spot of ground directly beneath the squirrel and hold your sights as if the squirrel was there - i.e., if the squirrel is about 25 yards away from you as the bullet flies but directly over a patch of ground 10 yards away from you, hold your sights on him as if he was ten yards away. That should get close enough to make meat out of him.

 

[bender20]

Spence explained this really well not to terribly long ago. I’ve not had much luck with the search feature on this site. Don’t remember the title of the original post.

 

[Zonie]

You shouldn't propose such hypothetical situations.....because "how high?" is the normal response?

I like your sarcasm .....Fred

I've heard How Hi is a Chinaman.

That's a statement, not a question. :rotf:

(My apologies to anyone who takes offense to this bit of humor.)

 

[George]

I don't mind, Zonie, but my revered Grandfather Ho Hum wasn't impressed.

Spence

 

[coloradoclyde]

:rotf:

 

[nhmoose]

:thumbsup: :rotf:

 

[Carl Fowler III]

Holding low for all shots at 45°angle or greater is correct procedure! If your standing 10 yards from a tree shooting at a squirrel 25 yards up that tree, then you better be holding low because that ball will shoot as if you were shooting at 10 yards!

 

[Black Hand]

If the angle of the shot is plus or minus 45 degrees, aim low on the target or game.

I aim at my target, the angle should make no difference - gravity is a constant regardless of your initial angle and will attract the ball in the same way. The ballistic trajectory really doesn't change whether you are shooting dead level, down or up. The only thing that changes is where the arc is interrupted by the ground.

This is incorrect, at least technically. Gravity remains a constant, but the angle at which it exerts its force differs depending on the elevation of the shot, and that will alter the trajectory.

Down is down, the angle has no effect on gravitational attraction (hence, the fact that gravity is a constant). The trajectory is parabolic whether you shoot flat, up or down - 25 yards flat or 25 yards at a 45 degree angle is still 25 yards.

 

[tenngun]

At long range it makes a difference but with small bore light loads and 15-25 yards I don’t think it makes a difference.

 

[George]

Down is down, the angle has no effect on gravitational attraction (hence, the fact that gravity is a constant). The trajectory is parabolic whether you shoot flat, up or down - 25 yards flat or 25 yards at a 45 degree angle is still 25 yards.

All true, but that doesn't mean there is no problem. As a matter of fact, it's because gravity can only work 'down', vertically, that the problem exists. If the attraction of gravity could be tilted like the gun can, there would be no slant range error.

Whenever the topic of shooting uphill and downhill comes up, someone invariably puts forth the idea that the solution to the problem is to aim as though the ball only traveled the horizontal distance to the target. I believe three people have mentioned that in this one thread. As I understand it, the idea is that gravity supposedly only works on the horizontal component of the ball's travel, not the slant one, so drop would be less and the gun would therefor shoot high. Someone who sees it that way, is that the idea?

Spence

 

[Elnathan]

As I understand it, the idea is that gravity supposedly only works on the horizontal component of the ball's travel, not the slant one, so drop would be less and the gun would therefor shoot high. Someone who sees it that way, is that the idea?

Spence

Hmmm. No, but that is a simplified mathematical model that works well enough to be useful in the field, or at least so I am told. Again, I haven't actually tried it.

Gravity pulls down, i.e., towards the earth, at a constant force. The angle at which it pulls relative to the initial path of the bullet depends on the direction. If the bullet initally is traveling horizontally (the barrel being held exactly horizontally) the force exerted the propellant and the force of gravity are acting independently, one forcing the ball in one direction and one in another - the curve in the result of those two forces (plus wind resistance) acting on a single object. Shoot upward, and the force of the propellant and gravity are now partially cancelling each other out. Here is a diagram that might or might not help:

g=gravity
p=propellant
w=wind resistance

In the upward shot the gravity is now partially pulling against the force of the propellant, and as the angle changes the exact interaction will change. Wind resistance will continue to act on the ball proportionate to its velocity regardless of its path, which is why its vector is drawn as curved curved. Eventually, as the angle rises to straight up and down, the trajectory of the shot will become straight as all three forces now act in direct line with each other. This will obvious alter the distance at which the line of sight and the path of the ball converge - whether this means you should hold high or low depends on the range and where the lines converge on the new trajectory.

Unless you live in Black Hand's world, in which shooting up is easy but standing up may be difficult... :shocked2:

Hopefully that all makes sense. It has been 18 years since I sat in my father's high school physics class and learned about force vectors, and while I think I remember the principles I've pretty much forgotten all the math and the details about how to diagram the vectors. I'm also kind of sleep deprived at the moment...

 

[George]

Hopefully that all makes sense.

Well, not totally.

You seem to be describing the rather standard explanation of why bullets shoot in something similar to a parabola rather than in a straight line. It would be easier for anyone to get their head around if you left the bit about shooting straight up and straight down out of the discussion. The effect of gravity on bullet velocity and thus trajectory is negligible and just tends to add unneeded complexity to an already complex problem.

Mainly, though, what I was asking about was the idea that people put forward that you only need to consider the horizontal distance from shooter to target when shooting uphill or downhill. If you touched on that question I missed it.

BTW, the gravity vector is always perfectly vertical, even Black Hand's, as he was at pains to point out.

Spence

 

[coloradoclyde]

Elnathan is right.... Two bullets will only strike the ground at the same time if they are perfectly parallel to each other ....And in a vacuum, as air resistance can provide lift counteracting gravity.
Especially a rotating sphere. like a round ball...
this is known as the Kutta-Joukowski lift theorem.
Lift per unit length of a cylinder acts perpendicular to the velocity.

All that is necessary to create lift is to turn a flow of air. The airfoil of a wing turns a flow, and so does a rotating cylinder. A spinning ball also turns a flow and generates an aerodynamic lift force.

Yes!....It's rocket science.... :grin:

 

[George]

Where would you be without Wikipedia, Clyde? :haha: :haha:

Spence

 

[azmntman]

:surrender: so should I shoot hi, low, dead on or just shoot em on the ground only?

:blah:

 

[Elnathan]

You seem to be describing the rather standard explanation of why bullets shoot in something similar to a parabola rather than in a straight line. It would be easier for anyone to get their head around if you left the bit about shooting straight up and straight down out of the discussion. The effect of gravity on bullet velocity and thus trajectory is negligible and just tends to add unneeded complexity to an already complex problem.

Why yes, yes I am. The shape of that trajectory will change as the angle changes, though. That is why I keep harping straight up and straight down - the trajectory changes from a parabolic arch to straight line, proof positive that the trajectory does not stay constant and should be really easy to visualize.

Black Hand's suggestion that the trajectory does not alter regardless of the elevation of the bullet is nonsense precisely because the vector of gravity remains vertical. Since it remains vertical while the vector of the propellant/angle of the barrel changes, the relationship between the two vectors changes. Since the relationship between the two vectors changes, the trajectory changes. Simple, really.

Mainly, though, what I was asking about was the idea that people put forward that you only need to consider the horizontal distance from shooter to target when shooting uphill or downhill. If you touched on that question I missed it.

I did. My guess was "false but useful" - which is to say that your state reason for why it works would probably give a physicist fits but the actual results would close enough to perfect that you wouldn't care.

 

[coloradoclyde]

Where would you be without Wikipedia, Clyde? :haha: :haha:

Spence

Actually, I got it from N.A.S.A. but, I was given a set of encyclopedias as a kindergartener... :grin:

 

[George]

The shape of that trajectory will change as the angle changes, though.

[clip]

Black Hand's suggestion that the trajectory does not alter regardless of the elevation of the bullet is nonsense precisely because the vector of gravity remains vertical. Since it remains vertical while the vector of the propellant/angle of the barrel changes, the relationship between the two vectors changes. Since the relationship between the two vectors changes, the trajectory changes. Simple, really.

I think you are seriously overestimating the change in trajectory because of the elevated barrel. Any change is negligible.

Simple, maybe, wrong, certainly.

Characterizing an argument in discussions since as this as nonsense is unnecessary and not very friendly.

Spemce

 

[azmntman]

Ahhh guys lighten up! We all went to different high schools and had different teachers teaching the same thing differently. I of course was out hunting when they taught shooting parallels n triangles n such. I will get me a target and put it on a string and throw over a limb and do a test and then we will now to shoot a tad low, a tad high or right in the eye :haha:

All this math stuff I learned a longgg time ago is REALLY simple to learn (and I was VERY good at math back in the day). The rule to really learning it was the TEACHER. They all teach the same thing but some of em cannot get through period. In Chemistry we had a teacher that reached exactly one student (a hippie pot head Italian kid that was pretty cool). The rest of us graduated having NO CLUE :shocked2: :youcrazy: :surrender:

 

[Skychief]

To all, I brought a big old boar fox squirrel (the type destined for the slow cooker) out of a beech tree this evening. The shot was angled upward of course (approximately 20 degrees short of vertical) and his vector, soon after, became straight down vertical (he would have done Sir Isaak Newton proud). Point of aim was right at his beak, about 25-30 yards from my muzzle. No problem-o.

Lord love a smoothbore! :thumbsup:

Good hunting all, Skychief