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a2+b2=c2... distance vs gravity #9006989 02/17/24 01:30 PM
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Hey all. So, gravity affects an angled shot less than a shot parallel with the Earth. So velocity increases, so we would expect POI to move higher. However, most discussions I see about shot angles use ye ole a2+b2=c2... while this accounts for the change in the distance to target (fundamentally important), I don't think it actually calculates the change in the effect of gravity. Probably the gravitation effect is so small it wouldn't come into play until tremendous distances. If this is the case, why are we talking about gravity when we are really thinking about distance? Am I thinking about this wrong?

Re: a2+b2=c2... distance vs gravity [Re: QPM] #9006998 02/17/24 01:43 PM
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Gravity affects an item falling straight (dropped) the same as something in motion forward.


Pass the gravy.


Re: a2+b2=c2... distance vs gravity [Re: QPM] #9007015 02/17/24 02:01 PM
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As the angle increases, gravity is pulling the bullet forward as well as down. If you are 100’ from a target on level ground, and someone is 100’ directly above the target firing straight down, their bullet should strike first if fired simultaneously. So now draw an arc from your position to theirs, and as you move along that arc, gravity has less downward effect and more forward effect. I’m not going to look up the formula but I bet it’s out there.


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Re: a2+b2=c2... distance vs gravity [Re: QPM] #9007084 02/17/24 03:41 PM
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gravity is pulling the bullet forward as well as down. Opps, NOPE ( understand what you tried to say). Start trajectory level from bore centerline. Bullet ALWAYS goes DOWN. Amount depends on TIME of flight. Cant bore down, velocity adds to gravity.

Re: a2+b2=c2... distance vs gravity [Re: QPM] #9007115 02/17/24 04:29 PM
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Way way way over my head. Ill take a stab at it anyway with something to consider as opposed to an answer. I think your comment about "are we talking about gravity or distance" is key. Ask yourself if there was no gravity would there be any drop at all. Ill hang up and listen......


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Re: a2+b2=c2... distance vs gravity [Re: QPM] #9007199 02/17/24 07:34 PM
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An angle shot, from tree the aim point tis higher
do ta exit point being lower. Hitting heart & lungs.


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Re: a2+b2=c2... distance vs gravity [Re: QPM] #9007287 02/17/24 11:18 PM
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Lets just say most ammo has more variation shot to shot (extreme spread) than Gravity would effect velocity even if shooting straight up or down.

Better description from the Bullet Smiths at Sierra: https://www.sierrabullets.com/exterior-ballistics/3-3-effects-of-shooting-uphill-or-downhill/ than I might provide.


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Re: a2+b2=c2... distance vs gravity [Re: kmon11] #9007294 02/17/24 11:37 PM
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Originally Posted by kmon11
Lets just say most ammo has more variation shot to shot (extreme spread) than Gravity would effect velocity even if shooting straight up or down.

Better description from the Bullet Smiths at Sierra: https://www.sierrabullets.com/exterior-ballistics/3-3-effects-of-shooting-uphill-or-downhill/ than I might provide.









kmon, you can do better than sierra did, surely. I gave up on their explanation quickly.


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Re: a2+b2=c2... distance vs gravity [Re: duffas] #9007346 02/18/24 12:58 AM
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Originally Posted by duffas
Opps


Opps?

Drop a bullet of same weight from the same height as one fired level and they hit the ground at the same time on level ground. I said this already.


Pass the gravy.


Re: a2+b2=c2... distance vs gravity [Re: QPM] #9007348 02/18/24 01:00 AM
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Originally Posted by QPM
Hey all. So, gravity affects an angled shot less than a shot parallel with the Earth. So velocity increases, so we would expect POI to move higher. However, most discussions I see about shot angles use ye ole a2+b2=c2... while this accounts for the change in the distance to target (fundamentally important), I don't think it actually calculates the change in the effect of gravity. Probably the gravitation effect is so small it wouldn't come into play until tremendous distances. If this is the case, why are we talking about gravity when we are really thinking about distance? Am I thinking about this wrong?


Well, the Pythagorean Theorem has absolutely nothing to do with gravity (it is a geometry calculation). Generally, you are solving for the hypotenuse, but you can use it to work out any one variable so long as the other 2 are known.


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Re: a2+b2=c2... distance vs gravity [Re: QPM] #9007358 02/18/24 01:13 AM
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With this being the Open Hunting section rather than the Rifle section, I'm of the opinion trying to get a good rest is a hundred times more important than what's being discussed.

Re: a2+b2=c2... distance vs gravity [Re: QPM] #9007375 02/18/24 01:49 AM
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Took me a few minutes it has been a LOOOOONNNNNNGGGGG time since I took Calculus, and dynamics or used them.

Basically do not worry about velocity changes due to gravity just trajectory and that mostly at longer distances, yes there can be some shooting up or down but the percentage is so small extreme spread between ammo is more at hunting distances even out to 1000 yards.

Trajectory is where gravity will grab you or in this case the bullet or even your crossbow arrow.

Simple version Gravity accelerates at a constant of a little over 32.17fps/s2 velocity over time of that multiply by number of seconds for the velocity in fps.

In .5 seconds which was time of flight for my loads in the 7mmSTW that took .5 seconds to make it 500 yards the velocity from gravity was basically 16fps per second. towards down. But it had made it up to that at that distance at but it is not linier like this might suggest. These are just snapshots at that those times.
.1 second 3.2fps
.2 seconds 6.4fps
.3 seconds 9.6fps
.4 seconds 12.8fps
,5 seconds 16fps

As distance increases air resistance is working to slow the speed of the bullet while gravity over time is accelerating the speed of the bullet falling toward the center of the dirt.

that is why if you run a ballistics calculator out to say 1000 yards the bullet will drop a lot more between 900 yards and 1000 yards than it day say between 4 and 500 yards. Bullet is moving slower so it takes longer to get there and gravity has accelerated over time so from it the bullet is falling faster.

Shooting straight up or down gravity and air resistance are still in play but going straight down a bullet will keep accelerating from gravity up to a point where air resistance over comes the acceleration of gravity. Shoot straight up and gravity is slowing the bullet down as is air resistance though as the bullet climbs higher the air resistance becomes less as air gets thinner but gravity is still working pulling it toward the ground slowing it down.

Much easier for shooting to use a ballistics calculator give it the correct information and it will provide you the feedback needed to get you close to what will be seen in real life. That technology, higher BC bullets and dial for distance scopes took a lot out of what is needed to shoot long range along with rifles built to tighter tolerance and ammo the same customized for the rifle helps.

You can get all the vertical info easy these days but reading the wind in the field is another story. I have seen shot in a place that with a 20mph wind from my right and wind blowing left at the target a dead on hold worked at 500 yards. As has been said many times on this form drop is easy to get, judging the wind is an art. The calculations can give you a hold but that is for a consistent wind given not what happens in the field in most places.


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Re: a2+b2=c2... distance vs gravity [Re: Double Naught Spy] #9007377 02/18/24 01:51 AM
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Originally Posted by Double Naught Spy
Originally Posted by QPM
Hey all. So, gravity affects an angled shot less than a shot parallel with the Earth. So velocity increases, so we would expect POI to move higher. However, most discussions I see about shot angles use ye ole a2+b2=c2... while this accounts for the change in the distance to target (fundamentally important), I don't think it actually calculates the change in the effect of gravity. Probably the gravitation effect is so small it wouldn't come into play until tremendous distances. If this is the case, why are we talking about gravity when we are really thinking about distance? Am I thinking about this wrong?


Well, the Pythagorean Theorem has absolutely nothing to do with gravity (it is a geometry calculation). Generally, you are solving for the hypotenuse, but you can use it to work out any one variable so long as the other 2 are known.


Right, you want to know distance to target and find "b" either with the sine/cosine or Pythagorean gets you there. On a 325 yard shot from 200' up the results are 254 vs 248...

Last edited by QPM; 02/18/24 01:52 AM.
Re: a2+b2=c2... distance vs gravity [Re: ntxtrapper] #9007382 02/18/24 02:00 AM
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Originally Posted by ntxtrapper
With this being the Open Hunting section rather than the Rifle section, I'm of the opinion trying to get a good rest is a hundred times more important than what's being discussed.


Fully agree and a man needs to know his limitations, including shooting ability from different positions included. The only way to learn that is to do it over and over with purpose on targets. If you miss why did you miss and if you hit why did you hit and can you repeat it. If my shooting position is not stabile enough to not be in the vitals adjust or just don't take the shot.


lf the saying "Liar, Liar your pants on fire" were true
Mainstream news might be fun to watch
Re: a2+b2=c2... distance vs gravity [Re: kmon11] #9007557 02/18/24 04:23 PM
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Originally Posted by kmon11
Originally Posted by ntxtrapper
With this being the Open Hunting section rather than the Rifle section, I'm of the opinion trying to get a good rest is a hundred times more important than what's being discussed.


Fully agree and a man needs to know his limitations, including shooting ability from different positions included. The only way to learn that is to do it over and over with purpose on targets. If you miss why did you miss and if you hit why did you hit and can you repeat it. If my shooting position is not stabile enough to not be in the vitals adjust or just don't take the shot.

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Re: a2+b2=c2... distance vs gravity [Re: QPM] #9007605 02/18/24 06:36 PM
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With that terrain, I would worry too much about elevation changes on bullet POI.

Re: a2+b2=c2... distance vs gravity [Re: QPM] #9007643 02/18/24 08:41 PM
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This hurts my brain.

Re: a2+b2=c2... distance vs gravity [Re: Jiggamitch] #9007701 02/18/24 10:30 PM
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Originally Posted by Jiggamitch
This hurts my brain.

You and me both.


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Keep your gratitude higher than your expectations. RWH
Re: a2+b2=c2... distance vs gravity [Re: QPM] #9007773 02/19/24 01:07 AM
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As was said before, gravity affects both the exact same.

Take two bullets of same weight fired from a rifle exactly parallel to the ground (theoretic i know) and the determining factor for distance travelled is the powder charge behind the bullet. The bullets will drop at the same time, one will just go faster and longer if there is a powder charge difference.

Changing the trajectory of the rifle only affects the amount of time before the bullet hits ground.
What a ballistic calculator does is account for a difference in known range and compensate for the angular shot to give a correct distance to aim at. This angular correction has as little to do with the gravitational pull on a bullet as setting zero on the rifle scope. You set the scope for a zero based on how the rifle shoots a bullet, and little care goes into gravity. The angular correction a rangefinder gives (if equipped) is simply a correction for the zero within the rifle system and where to aim.


For long distance shots where aim point is adjusted for range, the reason a bullet drops more at further distance is only related to the speed the bullet is going, meaning the distance the bullet covers over a given time. The speed has no bearing on gravity pull on the bullet as that is constant, but what happens is as the bullet slows down it is traveling for a longer time, gravity works on it longer and it drops more. A bullet dropped from a hand will fall to the ground in X seconds, lets say half a second. That same bullet going (consistently) 3000 fps from your hand will travel 1500 feet/500 yards in that same half second, of course not accounting for wind resistance and the speed actually slowing through that flight path. Does that make sense?

Re: a2+b2=c2... distance vs gravity [Re: QPM] #9007818 02/19/24 02:39 AM
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Gravity as explained does not exist. There is no gravitational pull, pulling dowwn to earth. There is pressure from space, the same pressure put there by God that keeps things in their proper positions. An object going horizontal will have more pressure (not pull) than an object going from a given height. headed downward because it is already on a natural course and more apt to "freefall".


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Re: a2+b2=c2... distance vs gravity [Re: QPM] #9007845 02/19/24 03:51 AM
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A bullet starts dropping the second it leaves the barrel no matter how fast.

Re: a2+b2=c2... distance vs gravity [Re: QPM] #9007848 02/19/24 04:01 AM
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Shooting angled shots, your old lasers are lasering the hypotenuse of the triangle.

Your bullet is going to drop based on the level distance. If memory serves, a 35° down angle then reduce the distance by 10%. This matter more, with the longer distance. 500 yards, reduce by 10%, so make a scope correction for 450 yards. Instead of 2.6 Mils, it's 2.2 Mils

Look at that at 300 yards, versus 270 yards. That's not a big difference in elevation correction. 300 yards 1.0 Mil, 270 yards .8 Mil

The greater the angle, the greater percentage you take off the lasered distance. That's the old cosine indicator that was mounted on scope tube.

Now days, this is a moot point. Lots of range finders compensate for angle.

Bow hunters need to worry about this more than rifle hunters. Stand at the base of your tree, and laser other objects in your hunting area. Then climb 30' up that tree to your stand. You need to know that level distance lasered distances you took from the ground, and built your range card. That's the distance the arrow flies, affected by gravity.

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Re: a2+b2=c2... distance vs gravity [Re: QPM] #9010696 02/24/24 06:16 PM
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Mr Gas guzzler - drop a feather and a lead weight from the Tower of Pizza and they hit the ground at same time. 32 ft/sec^2. For one sec flight time, fps is 32. Add some of the muzzle fps to downward flight if the rifle is pointed down.

Re: a2+b2=c2... distance vs gravity [Re: duffas] #9010723 02/24/24 07:30 PM
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Originally Posted by duffas
Mr Gas guzzler - drop a feather and a lead weight from the Tower of Pizza and they hit the ground at same time. 32 ft/sec^2. For one sec flight time, fps is 32. Add some of the muzzle fps to downward flight if the rifle is pointed down.

The feather will fall much slower due to air resistance.

Re: a2+b2=c2... distance vs gravity [Re: QPM] #9010732 02/24/24 08:05 PM
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A bullet parallel to the ground is affected by the same gravity as a bullet shot upward angle and as one shot at a downward angle. This gravity force is nearly constant across the globe, with extremempy minor changes for altitude, but these are inconsequential when determining bullet flight path.

The variables that make the biggest difference on flight path are speed of bullet and wind resistance of that bullet. Gravity affects all bullets the same so that factor is not even considered in ballistic calculators. So all this nonsense about gravity in bullet path is purely just that, non sense.

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