Considerations when Employing Numerical Simulation Software


I would like to offer some additional context to the discussions leading up to this video. I graduated with a structural engineering degree. Currently, I program and utilize software for finite element analysis. As with using any kind of complicated software, in this instance ballistic solvers, certain limitations and considerations apply that the user must be fully aware of.

Observation

To most end-users, ballistic solvers are “black boxes”, mandating some input (atmospherics, bullet characterization, etc.), processing it and returning an output (firing solution). Consequence 1. You do not know, (a) which effects are included in the displayed firing solution and (b) even if they are, which formulas/approximations are used to model the bullet’s flight. Good documentation is a rare commodity.

2. You have no way of knowing if there are errors in the code that calculates your firing solution.

Observation

A computer program consists of a fixed set of instructions, executed by the computer, which are based on algorithms provided by the programmer.

Consequence 1. A computer will never be able to perform a task it was not programmed for. 2. 2. A computers reasoning is based on rigid logic. This makes for dependability/repeatability, but a very limited set of tasks it can successfully handle. Do not expect it to be able to “think outside the box”. If the logic does not account for a certain feature, it cannot be dynamically appended at a moments notice. Neither can it validate any input data you provide.

3. In this respect, we consider computers as “dumb”.

4. You provide the intelligence, the computer provides the rote mathematical operations.

5. If you do not provide the program with proper input, do not expect the output to be usable. The old adage is “garbage in, garbage out”.

6.Hence, the computer is limited to the extent of your capabilities. Given incorrect input, it will without fail reach the wrong firing solution, but get there several trillion times faster than if you had to do it by hand.

Observation

Numerical simulations are sensitive to variations in input data.

Consequence Common sources of input related error include, but are not limited to: 1. inaccurately determined performance numbers, i.e., MV, BC, scope tracking corrections, etc. 2. typos and sign errors, i.e., left vs right twist, orientation of shooting or direction of wind. 3. Inadvertently using the wrong/inconsistent set of units and their conversions. Providing input in a different manor than the program expects, i.e., G1 vs G7, density altitude vs normalized air pressure vs station pressure, to name a few.

Observation

Very few ballistic solvers actually utilize the full 6DOF equations to model the bullet’s flight path. Often, excellent and sufficient approximations can be obtained by models with a significantly reduced level of detail / higher level of abstraction.

Consequence

1. In order to perform 6DOF calculations, one requires knowledge of many more input variables and their values. Gathering this data is a very laborious process. The potential accuracy gain from going to 6DOF can be severely diminished by the new uncertainties introduced in the additionally required input quantities. 2. Unless extensive testing is performed and knowledge of the bullet is available, 6DOF calculations are inaccessible to the average shooter, but thankfully rarely required. 3. One such unique use-case is in determining the dynamic stability of the bullet as it reaches and passes through the transonic zone. In order to circumvent this shortcoming in current state of the art ballistic solvers, which use high level abstraction formulations of the bullet’s flight path, trueing of the ballistics solver is required.

Observation

Top tier ballistic solvers offer solid holds, when trued to your weapons system and employed correctly, and will put you on target if you do your part as the shooter.

Consequence

Just because you own a new gadget does not mean you can afford to neglect other key components such as:

[if !supportLists]1. [endif]Fundamentals of marksmanship

[if !supportLists]2. [endif]Documentation & Strategy

Sound equipment

Take home message:

In conclusion, ballistic solvers, and for that matter all other numerical methods, are meant to supplement, complement and enhance existing methods, but under no circumstances replace them completely. In order to become a viable long range precision shooter, you need to be able to verify that the firing solution you obtain from the ballistic solver is in the right ball park. Such reality checks are performed based on knowledge of previous engagements, other preexisting firing solution tables you might have access to and a basic understanding of the underlying physics couple strongly with intuition and experience.

Since we work in the field, I briefly recall PACE to further impress that the ballistics solver is just one part in your bag of tricks.

Primary

Alternative

Contingency

Emergency

You must dedicate substantial time to familiarize yourself with these new tools before you use them. After all, blindly trusting the output of a ballistics solver is very much like having somebody you don’t know pack your parachute.

Thanks for your time!

Kind regards

Adrian


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