Here are some pics I've wanted to put up but just haven't had the time. Most are of Chuck Nozicka's Honest John, but I have a couple of Mr. Jurk's Jumanji on a K1000 Skidmark.

Zoom in on the flame on Chuck's HJ: just can really see the mach diamonds.

For those of you who want to understand how mach diamonds form, check out this site:

http://www.aerospaceweb.org/question/propulsion/q0224.shtml

Ed