Boatright & Ruiz

Calculating Aerodynamic Jump for Firing Point Conditions - Boatright & Ruiz Method

Aerodynamic Jump is at the front of every Long Range Shooter's mind right now, Jim Boatright and Gus Ruiz take a detailed look at Crosswind Aerodynamic Jump and break down their method for calculation. Download the full report and the execution files necessary to figure this ballistic effect correctly.

Ballistic calculators have made the work of the long range shooter much easier over the last few years.  They are getting better and more detailed as the authors learn to incorporate the various drifts and drops into the formulas, hopefully making the predictions better under a wider variety of situations.   Determining what is right and what is only almost right is the hardest part for the end users.   People constantly want to know which is better ? 

When I started my journey down the long range shooting path, ballisticians were mostly behind closed doors in top secret laboratories. The first real public figure in this field was Gerald Perry.  Gerald was the author of ExBal, one of the first ballistic applications, if not the first to offer a commercial solver.  His work opened the door for Lex Talus and Field Firing Solutions, we had Horus ATRAG on the old PDAs, and then LoadBase from Patagonia Ballistics hit the streets.  About the same time Gerald Perry passed away, Bryan Litz came on the scene and has built a brand that is widely recognized by everyone here in the US and abroad.  

Less recognized, is the continued worked in the field of long range shooting done by Gus Ruiz from Patagonia Ballistics. As the name suggests, Patagonia Ballistics is not a US based company, and Gus tends to work behind the scenes vs actively out front.  From ColdBore 1.0 to TRASOL from Desert Tech, Gus is the man behind the engine that powers these outstanding applications. When people ask me what makes one program better than the other, Gus is really the short answer.  He takes a much more detailed approached to solving the problems associated to long range shooting and this is displayed in his solutions. 

Patagonia Ballistics

Someone wrote just this week in the Sniper's Hide forums that the average guy doesn't care what is behind the curtain of any given solver, only whether the end results are valid and repeatable. After all, it's the end results we are interested in.  We can certainly tweak and true the calculator, manipulating the numbers to produce the desired outcome. But at the end of the day, we also have access to better equipment so why tweak their data ? We spend real money on stuff like the new chronographs, from the LabRadar to the MagnetoSpeed, we are getting much better information up front than ever before.  This has been Gus's approach since I was first introduced to him. Taking the known errors and correcting them in the software, understanding the pioneers in the ballistic world who came before him had their limitations too.  Some times the stuff from back in the day is flawed. 

Calculating Aerodynamic Jump for the Firing Conditions 

Boatright & Ruiz

A Novel and Practical Approach for computing the wind induced jump perturbations- 

Gus Ruiz partnered up with Jim Boatright to author this paper and calculator made available here so the end user can determine the correct CWAJ.  Jim is the author of the Coning Theory which can be used to calculate aiming corrections for the long range shooter which go beyond our typical 3 DOF Point Mass solvers. Not quite a 6 DOF simulation, but pretty close, calculating the spin rate and spin axis of the bullet continually throughout it's entire flight. 

Both Gus and Jim built on the work done by McCoy and his work in this field at the Aberdeen Providing Ground.  Their paper references the early work and using Jim's Coning Theory they now can make an analytical calculation to determine the effects of the crosswind aerodynamic jump. 

Link to the Paper : Calculating Aerodynamic Jump for the Firing Conditions 

This paper is available for unrestricted download and features the .exe file to calculate the effect at the user level. 

Some important take aways from the Paper: 

1. They use the rifle, bullet, and local shooting environment that is easily measured at the shooter, in either near real time or just before. 

2. The corrections can be added to the shooter's scope or sights 

3. These calculations do not rely on downrange wind conditions 

4. Neither Gravity or Coriolis have any effect here since they are not aerodynamic 

5. CWAJ happens just beyond the muzzle blast and is completed within, 10 yards (roughly) of the muzzle. This is a one time effect. 

The coning motion causes very little or no further angular deflection during the remainder of the bullets' flight. This question comes up as many question the swerve of the bullet and it's downrange effects. 

Litz Method 

Boatright & Ruiz

There is a direct comparison to the method being used by Bryan Litz. This will be of special interest to many as there is very little dissension in what he does.  We are bit closed off to other thoughts on the subject of long range ballistics and I feel it is important to understand,  not everyone always agrees. I know Bryan was copied on much of this work as it was going forward and to my knowledge he did respond to the open call for questions of comments. 

For the new or average shooter, this stuff is minor, and the work Bryan has done in this field has brought our understanding of long range shooting to a new level. That is to be applauded. But, there is more than one way to skin a cat, and we should be open to other ideas and methods.  I'm not a bandwagon type person, I look at as many sides of a situation as possible and draw conclusions based on my personal experience ( ie: my end results ) as well as the data put forth by multiple sources.  

I understand this may appear to be a North / South Rap Battle, but for us, results are all that matter.  Dueling papers on these subjects is something that has been missing for the last dozen years.   From Dr. Pejsa to Gerald Perry, both these pioneers in ballistics have passed away leaving a vacuum in our knowledge base. Hopefully that changes as we move forward.  It would be a plus for all of us, the end users. 

I want to thank Jim and Gus for their hard work and making this available to everyone. I hope this begins a dialog to address even more in the area of long range shooting. With the new tools that are becoming available, we can expect to constantly having the old norms tweaked and adjusted as we move forward.    

My next request would be in the area of wind. I think David Tubb is on to something with the slightly off center value being stronger than a 9 O Clock or 3 O Clock value.  That shorter distance for the bullet to weather wane makes perfect sense to me.  

Thanks for reading.