Does any ballistic app or software have a graph that shows the LOS in relation to the bullet trajectory?

[DocUSMCRetired]

If you could drop a bullet at the exact same instant that a fired bullet leaves the muzzle and the barrel was parallel to the ground or surface, they would fall at the same rate and impact the ground at the same time.

They will not hit the ground at the same time.

Is that what you are saying? Cause I gotta say I’ve read every AB book. I have 3 volumes of some and I have never seen this described or discussed in the books nor have I ever seen a trajectory where this occurs.

The vertical deflection is miniscule, but it does exist. The circle in the middle is the bore centerline. Less than 1/2 of 1 degree. So it is absolutely hard to catch.

 

[Marine52]

Ok. @DocUSMCRetired you’re going to have to explain this to me. I literally thought about this all night and based on what you are saying here is that AJ cause a vertical instantaneous vector as the bullet leaves the barrel causing it to momentarily rise above the line of departure (it would look similar to the vote counted in amichigan the night Biden got elected)

View attachment 8433642

Is that what you are saying? Cause I gotta say I’ve read every AB book. I have 3 volumes of some and I have never seen this described or discussed in the books nor have I ever seen a trajectory where this occurs.

It would be my understanding that the rise or fall of AJ occurs over the course of the trajectory not at one single instant and the correction is baked into the firing solution.

Again I’m not saying you’re wrong I just need to see the maths or see proof. Help me out.

AJ occurs in the first several yards of bullet travel and diminishes as the bullet precession cycle ends. But the angular correction maintains for the entire flight of the bullet. Whether of not it’s enough to provide enough vertical jump to answer your question is a tough one. Bryan Litz did a lot of good research on this. Here’s a post of his from another forum:

BRYAN LITZ:

There are three different vertical considerations to make with wind.

One is simply the effect of the wind following the terrain and developing an 'updraft'.(or downdraft) In this case, the wind is deflecting the bullet same as a cross wind, just up or down. You usually don't see much of this if you're shooting over flat ground, more so when shooting over canyons, hill to hill, etc.

The other effect is what's been discussed (the 10 O'clock to 4 O'clock slant of a group). This happens due to a mechanism called aerodynamic jump. When the bullet emerges from the muzzle into a crosswind, it weathervanes into the net airstream, which will be at a slight angle due to the cross-wind. The bullet sees a 3000 fps headwind, and a 15 fps (10 mph) crosswind, so the bullet has to weather-vane less than 1/2 of one degree. As the bullets axis is torqued to realign that slight angle, it reacts with a series of precession cycles, the result of which cause a slight vertical deflection called 'aerodynamic jump' (AJ).

AJ is a fixed angular amount at the muzzle, meaning that if it's 1/2" at 100 yards, it will be 5" at 1000 yards. It's not a parabolic growth like wind drift which might be 1" at 100 but 80" at 1000. This is because horizontal wind deflection acts on the bullet for it's whole flight, while AJ is a lunch effect that's established within 15-20 yards from the muzzle. That's why it's called 'jump'.
One place AJ used to cause problems was for .50 cal waist gunners on WW2 era bombers. They're firing into 100's of mph of crosswind, and depending on which side they were firing from would determine if the jump was up or down. Not a precision shooting application, but high crosswind.

The magnitude of AJ depends on bullet stability, with higher stability producing greater AJ. For a 10 mph crosswind and typical LR rifle, you'll see something like 0.2 MOA of AJ compared to no wind.

In a long range shooting match such as BR or F-class, it's not likely that you'll have to correct for AJ. Assuming you shoot sighters in the prevailing wind, AJ is the same for every shot so if the wind is 15 mph +/-5 mph crosswind (a difficult condition), the worst you'll see on the target is less than a 1/4 MOA click of vertical from AJ. But you could see much bigger vertical effects from actual vertical wind currents, or direction changes (head/tail component).

Usually, if you shoot big vertical in big wind it's due to the vertical wind currents that develop over terrain and the general turbulance of the air, not AJ.

The final way high winds can affect vertical is the head-wind acting to slow the bullet more, and a tail wind acting the other way. These effects are minor compared to crosswind, but if you have a big direction change mid string, it may show up as a few inches of vertical at 1000.

-Bryan

 

[_Windrider_]

AJ occurs in the first several yards of bullet travel and diminishes as the bullet precession cycle ends. But the angular correction maintains for the entire flight of the bullet. Whether of not it’s enough to provide enough vertical jump to answer your question is a tough one. Bryan Litz did a lot of good research on this. Here’s a post of his from another forum:

BRYAN LITZ:

That’s what I’m getting at. I know what it does but I struggle to believe the full effect of it is instantaneous at the muzzle and could cause it to go above the line of departure. I just don’t see that happening especially at even 1/10 of a second the bullet has already traveled a hundred feet or more moving it’s trajectory even further from the line of departure

 

[DocUSMCRetired]

That’s what I’m getting at. I know what it does but I struggle to believe the full effect of it is instantaneous at the muzzle and could cause it to go above the line of departure. I just don’t see that happening especially at even 1/10 of a second the bullet has already traveled a hundred feet or more moving it’s trajectory even further from the line of departure

I ran it. At 3 feet the bullet was 0.01 inches above the center of bore with a 10 mph 3 o'clock wind. So yes, it was above the center of bore even if only for a moment. I didn't continue the simulation to determine where it leveled back to center with the bore again.

 

[_Windrider_]

I ran it. At 3 feet the bullet was 0.01 inches above the center of bore with a 10 mph 3 o'clock wind. So yes, it was above the center of bore even if only for a moment. I didn't continue the simulation to determine where it leveled back to center with the bore again.

10-4

 

[carbonbased]

I ran it. At 3 feet the bullet was 0.01 inches above the center of bore with a 10 mph 3 o'clock wind. So yes, it was above the center of bore even if only for a moment. I didn't continue the simulation to determine where it leveled back to center with the bore again.

That’s it. I’m zeroing at 3ft from now on lol