Range Report Bullet Wobble

[Dlowman]

Has anyone developed a formula to predict the exact position of a bullet during it's corkscrew trajectory? What I am getting at is that when a bllet exits the barrel the rifling causes the bullet to spin. Assuming that no bullet is perfectly balanced, it will wobble slightly causing the bullet to fly in a slight corkscrew path. The farther the bullet travels, the larger the variance from a straight linear path. I am familiar with unbalanced rotational shaft formulas used in the manufacturing process of generators and jet engines, but I was wondering if anyone has applied this methodology to bullet trajectories and placement? Or am I way out in left field on this?

 

[Killswitch Engage]

Re: Bullet Wobble

i would think you are referring to spin drift which comes into play at longer ranges due to the rotation of the bullet pulling it in the direction of rotation. im not super smart on that shit and really don't worry about it. most ballistic programs have a section for it. i use shooter and it has a spin drift section.

wobble would be what you would see when the bullet is passing throught the transonic region of flight. depending on the bullet and its shape it my or may not be tempermental to the transonic transition.

my .02 but you prolly got .01 worth.

 

[TiroFijo]

Re: Bullet Wobble

Check this:

http://www.appliedballisticsllc.com/epswerve.html

 

[George63]

Re: Bullet Wobble

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TiroFijo</div><div class="ubbcode-body">Check this:

http://www.appliedballisticsllc.com/epswerve.html </div></div>
better yet buy his book, puts it all into perspective - the basic conclusion: spend 20 years perfecting your wind correction before considering some of the remote factors

 

[BryanLitz]

Re: Bullet Wobble

The equations for epicyclic motion are well established. The link to the video above is actual output from a 6 degree of freedom simulation to the equations of aeroballistic motion, including epicyclic effects.

The summary is that the 'corkscrew' flight path is so minor, like 0.01" in radius, that it's observable effects on trajectory are insignificant. You may find some special cases where bullets having certain properties will have larger radius', but those bullets would have been identified as less accurate, and not commonly used in LR shooting.

spin drift is unrelated.

-Bryan

 

[Dlowman]

Re: Bullet Wobble

Thanks for the straight answer, Bryan. I just bought your book, but have not had time to read it all. It looks like you already covered the wobble that I am worried about completely. After shooting for 35 years I guess I am trying find ghosts.
Thanks for your answers everyone.

 

[Greg Langelius *]

Re: Bullet Wobble

I spent a lot of time considering all the things that can happen with a bullet, then realized I was assigning them a far greater magnitude than they deserved.

In essence, think less, shoot more.

It's not a problem unless you can point to it right there on the target. Then, if you have a real problem, is the time to invert yoru time thinking about fixing it.

Shooting is a lot easier when you just get out there and do it.

Greg

 

[MitchAlsup]

Re: Bullet Wobble

Adding to what Bryan said: If the corkscrew diameter gets to be as large as 1/3rd of the diameter (?or was that radius?) of the bullet, the bullet and its flight path become unstable.