{"id":2006,"date":"2024-03-14T19:59:21","date_gmt":"2024-03-15T00:59:21","guid":{"rendered":"https:\/\/david.bookstaber.com\/Interests\/?p=2006"},"modified":"2024-03-14T19:59:21","modified_gmt":"2024-03-15T00:59:21","slug":"improved-ballistic-calculator","status":"publish","type":"post","link":"https:\/\/david.bookstaber.com\/Interests\/2024\/03\/improved-ballistic-calculator\/","title":{"rendered":"Improved Ballistic Calculator"},"content":{"rendered":"\n
\"Graphic<\/a>
Graphic I made to illustrate some of the concepts incorporated into the latest ballistic calculator.<\/figcaption><\/figure>\n\n\n\n

While working on my ballistics book I got sidetracked building a ballistic calculator. I wanted to programmatically generate some examples, so 6 months ago I went to see what was available in open source. As I have noted previously, Python is preferred for this sort of hacking<\/a>. I found this recently active Python project that looked promising and began to play with it<\/a>. I encountered some bugs, noted them on GitHub, and was soon collaborating with the Ukrainian developer behind the project. Since then I have sporadically worked on adding features and improving the code in my fork here<\/a>. These became quite extensive, and today we merged all of my work<\/a> into his repository as a version 2 release!<\/p>\n\n\n\n

One valuable feature set I added was to clearly handle non-zero look angles<\/em> \u2013 i.e., when the shooter is sighting above or below the horizon. All useful ballistic calculators accept look angle as an optional parameter, but none that I have seen make it clear in their output if\/when their distance and drop values are relative to the sight line or to the horizon.<\/p>\n\n\n\n

\"\"
One of the plots generated by the calculator, highlighting danger space for a specific target and trajectory.<\/figcaption><\/figure>\n\n\n\n

Technical details: The calculator simulates a ballistic trajectory using standard aerodynamic drag models together with a point-mass model of motion, sometimes referred to as 3 degree-of-freedom (3 DoF). It incorporates atmospheric variables, including multiple wind readings, as well as models of the change in air density by altitude over a trajectory. It adds Litz’s spin-drift approximation to windage, so I like to call it 3DoF+ since spin is another degree of freedom. (I don’t claim 4 degrees of freedom because the spin isn’t fully modelled. Amusingly, Hornady published a calculator under the trademark 4DOF\u00ae<\/sup> even though theirs likewise provides only auxiliary approximations of spin effects.)<\/p>\n","protected":false},"excerpt":{"rendered":"

While working on my ballistics book I got sidetracked building a ballistic calculator. I wanted to programmatically generate some examples, so 6 months ago I went to see what was available in open source. As I have noted previously, Python is preferred for this sort of hacking. I found this recently active Python project that […]<\/p>\n","protected":false},"author":3,"featured_media":2007,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[133,56],"tags":[],"class_list":["post-2006","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-ballistics","category-tech"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/david.bookstaber.com\/Interests\/wp-content\/uploads\/2024\/03\/BallisticTrig.png","jetpack_shortlink":"https:\/\/wp.me\/po3d1-wm","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/david.bookstaber.com\/Interests\/wp-json\/wp\/v2\/posts\/2006","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/david.bookstaber.com\/Interests\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/david.bookstaber.com\/Interests\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/david.bookstaber.com\/Interests\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/david.bookstaber.com\/Interests\/wp-json\/wp\/v2\/comments?post=2006"}],"version-history":[{"count":4,"href":"https:\/\/david.bookstaber.com\/Interests\/wp-json\/wp\/v2\/posts\/2006\/revisions"}],"predecessor-version":[{"id":2012,"href":"https:\/\/david.bookstaber.com\/Interests\/wp-json\/wp\/v2\/posts\/2006\/revisions\/2012"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/david.bookstaber.com\/Interests\/wp-json\/wp\/v2\/media\/2007"}],"wp:attachment":[{"href":"https:\/\/david.bookstaber.com\/Interests\/wp-json\/wp\/v2\/media?parent=2006"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/david.bookstaber.com\/Interests\/wp-json\/wp\/v2\/categories?post=2006"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/david.bookstaber.com\/Interests\/wp-json\/wp\/v2\/tags?post=2006"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}