Up/Downhill corrections

[jwp475]

I don't know. I don't use Exbal, but maybe there's a way you can enter up or down angles? Or maybe Exbal left something out???




I was just trying to help out. Stick you head in the sand if you want but here's the link, try it for yourself. http://www.eskimo.com/~jbm/calculations/traj/traj.html


SHOOTING UP: Gravity is working against the direction of the bullet when it's shot upward. This slows it down slightly and effects the trajectory which changes the point of impact lower relative to the drop using the same angle shooting down. The change is so slight that you don't really see a significant difference until your target is very far away - beyond a 1000 yards for most loads.

SHOOTING DOWN: Gravity is working in the same direction as the bullet when it's shot. This speeds it up slightly and effects the trajectory which changes the point of impact higher relative to the drop using the same angle shooting down.

It's Physics. I didn't make this up. You don't really see the effect until after 1000 yards. Make sure you change the range to 2000 yards otherwise the difference will only be a inch or two at a 1000 yards. If you want to see the effect even more, change the range to 3000 yards.

jwp475 and MagMan I tried to use small words, but if all this is too much for you to wrap your heads around then just continue to ignore physics and take Exbal's apparent lack of angle direction input as gospel proof that what I'm saying is wrong. I wouldn't want you to actually have to think about something.

My head is not in the sand did you read Shawns reply or not?

Your smart *** reply about typing slow isn't impressing at all..
What is your qualifications in Physics?

I dought that Exball left anything out, it is probable the most trusted and used program by experinced Long Range Hunters out there. Apparently your head is in the sand. I'll take my computor based Exbnall over the free online programs any day.

 

[jwp475]

I would invite you to use Exball but it is on my computer and Exball has to be purchased also my Dell Axiom Pocket computer has the Exball program on it to take into the field, try taking this one into the field, JBM - Calculations - Trajectory ain't happening. I've been aware of that web site for several years, and will not trade Exball for it..

 

[WildcatB]

I dought that Exball left anything out,

Let's see... I just checked Exbal's site and see that they don't ask for a latitude or compass direction of your shot... so they are not taking the coriolis effect into account.......hey... maybe you can use this as proof that the earth is not round at your next "Flat Earth Society" meeting.

I'll take my computor based Exbnall over the free online programs any day.,

-- and this proves that online programs are not computer based.

Your smart *** reply about typing slow isn't impressing at all..,

... what did I say about your typing?

 

[jwp475]

You said that you were typing slow for us to under stand, I guess that I am typing too fast for you.
Coriolis effect would be realavent if I was shooting a 105 Howitzer but I'm not. Again the Smart *** reply about the flat earth.
What is your Physics qualifications?

Again you have offered no proof, yet you ignore Shawn and he teaches Long Range to Civillians, Law Enforcement and Military what is your qualifications, beside being a samrt ***..

 

[WildcatB]

What is your Physics qualifications?

I can read.....and do the math.

 

[wildcat]

Pstimac, let me give you some advice. Don't let this guy get on your nerves, don't even post a comment back to him.

W.

 

[Buffalobob]

I am not going to get into an argument about it since I need Shawn to send me another cheekpiece being as I already used the one I ordered on a different rifle and now my new rifle is nearly done and it still needs a cheekpiece.

The acceleration of gravity is 32.2 ft per second squared.

The equations for calculating the velocity effect is 1/2 GxTxT. So for a time of travel of one second which would be about a 1,000 yard shot, the acceleration would generate a velocity of = 1/2x32.2x1x1 = 16.1 fps. If an angle is involved then multiply it by the sine. Thus, at 1000 yards we would see a small effect.

Now then lets us shoot at something 2000 yards away and things will get significant because "time of travel" is a squared function and it will take about 3.5 seconds to get there.

So the added or subtracted velocity = 1/2x 32.2x3.5x3.5 = 197 fps. Correct that for the angle of say 45 degrees and you get 197 fps x Sine 45 (0.707) = 139fps. (we use the sine function rather than the cosine function)

Being as one shot is uphill, its velocity is reduced by 137 fps and the other one is going downhill, its velocity is increased by 137 fps. So total difference is 274 fps by the time it reaches the target.

This is a simplified calculation that assumes the bullet path is a straight line and that is not true. The bullet travels along a curve and depending upon the angle a bullet fired uphill may actually start out going "up" but then change to "level" flight at some point and then tip over into "down" flight as it nears its target.

Think about things like this. If you go out in a boat and fire a 22 rifle straight up in the air gravity finally stops it and then begins to accelerate it back down and you will see and hear it "plunk" into the water. This is the simplest of all situations. If you have never done this then you simply don't meet minimum qualifications to be a redneck.

This is what I think. Perhaps I am wrong. It would not be the first time in my life I was wrong.

Anyway, I have no intentions of arguing about it. I use Exbal on my PDA and JBM on my PC.

 

[jwp475]

I can read.....and do the math.

Can you read this?

The angle is all that matters from horizonal, it does not matter if it is up or down just that it is. A given 45 degree shot uphill is the same dope as the same shot but 45 degrees downhill.

 

[jwp475]

Pstimac, let me give you some advice. Don't let this guy get on your nerves, don't even post a comment back to him.

W.

Nothing of substance as ussual, perhaps will will see thread number 20 soon...

 

[Shawn Carlock]

Bob,

I don't mind friendly debate. I'll send you a cheekpiece anytime you want.

I was taught long ago it didn't matter if it was up or downhill and have applyed that in the field ever since without giving much thought to it other than the base theory. I have had great success with disregarding up or down. That being said I have not had opportunity to shoot up/downhill shots of huge distance and angle. 2000 yard shots with any angle at all (say over 15 degrees) just don't happen in this part of the world. What you say about the up/downhill gravity effect makes since to me I just have never seen it in the field ( that doesn't mean it isn't happening). I am sure that gravational deceleration occurs and will effect a given shot to a given extent. I beleive that few would ever have the occasion to shoot the distance and angle for it to be an issue. If the effect occurs at 3000 yards with an angle of 15 degrees or more I am not to worried about that. I will continue to teach that it doesn't matter, simply because it occurs at distances and angles rarely encountered by anyone. So I guess in my mind it is one of those issues where it does exist but is such a rare field occurance that it would only serve to confuse the subject and most people. It is an interesting issue and I am glad it was brought up. I like to know what is technically correct even if it doesn't effect my shooting.
As a side note to all who posted, this is likely the only civilized site left on the web lets keep it that way.

 

[MagMan]

Huh, well no kidding. It's a great morning, I learned something new. Sure would have though that it would have been brought up some time ago though. None the less, great information to know.

pstimac, I'm terribly sorry for questioning your knowledge on the subject.

 

[jwp475]

Exactly where is anyone going to find a 45 degree angle to shoot at 2000 plus yards, that being the case it makes no difference.

 

[piutemike]

Exactly where is anyone going to find a 45 degree angle to shoot at 2000 plus yards, that being the case it makes no difference.

Hey, it's ok to be wrong some of the time. I find it liberating not to have to be right all the time.

Mike

 

[WildcatB]

As a side note to all who posted, this is likely the only civilized site left on the web lets keep it that way.

Well said. I apologize too all. I got a little too defensive.

By the way Shawn, I ran the numbers on your 338 Edge.

If you ever pass through Elko, NV let me know. I can take you to a place where you can shoot long shots at 20 - 30 degree angles to see if these numbers are correct.