German Salazar trod similar ground more recently.
IIRC, he also included spark photography (as did Audette) or long exposure photography (i forget which) to image the prime flame front.
These days you’ll ha em to be motivated to find his work as he pulled much of it from online outlets.
I've got most of German's work from The Rifleman's Journal saved. He was thorough and put a lot of effort into his testing and documentation. -Al
